Hydrogeology and ground-water quality of the Chromic Acid Pit site, US Army Air Defense Artillery Center and Fort Bliss, El Paso, Texas

USGS Publications Warehouse

Abeyta, Cynthia G.; Thomas, C.L.

1996-01-01

The Chromic Acid Pit site is an inactive waste disposal site that is regulated by the Resource Conservation and Recovery Act of 1976. The 2.2-cubic-yard cement-lined pit was operated from 1980 to 1983 by a contractor to the U.S. Army Air Defense Artillery Center and Fort Bliss. The pit, located on the Fort Bliss military reservation, in El Paso, Texas, was used for disposal and evaporation of chromic acid waste generated from chrome plating operations. The site was certified closed in 1989 and the Texas Natural Resources Conservation Commission issued Permit Number HW-50296 (U.S. Environmental Protection Agency Permit Number TX4213720101), which approved and implemented post-closure care for the Chromic Acid Pit site. In accordance with an approved post-closure plan, the U.S. Geological Survey is cooperating with the U.S. Army in evaluating hydrogeologic conditions and ground- water quality at the site. One upgradient and two downgradient ground-water monitoring wells were installed adjacent to the chromic acid pit by a private contractor. Quarterly ground-water sampling of these wells by the U.S. Geological Survey began in December 1993. The Chromic Acid Pit site is situated in the Hueco Bolson intermontane valley. The Hueco Bolson is a primary source of ground water in the El Paso area. City of El Paso and U.S. Army water-supply wells are located on all sides of the study area and are completed 600 to more than 1,200 feet below land surface. The ground-water level in the area of the Chromic Acid Pit site has declined about 25 feet from 1982 to 1993. Depth to water at the Chromic Acid Pit site in September 1994 was about 284 feet below land surface; ground-water flow is to the southeast. Ground-water samples collected from monitoring wells at the Chromic Acid Pit site contained dissolved-solids concentrations of 442 to 564 milligrams per liter. Nitrate as nitrogen concentrations ranged from 2.1 to 2.7 milligrams per liter; nitrite plus nitrate as nitrogen concentrations ranged from 2.3 to 3.0 milligrams per liter. Nitrate concentrations are abnormally high in the Old Mesa well field located about 5,000 feet southwest of the Chromic Acid Pit site. Volatile and semivolatile organic compounds in water samples were analyzed for the first sampling round; no confirmed volatile or semivolatile organic compounds were detected above the laboratory reporting limits. Total chromium concentrations ranged from 0.0099 to 0.092 milligram per liter; dissolved chromium concentrations ranged from 0.0068 to 0.0094 milligram per liter. Overall, water-quality characteristics in water from the chromic acid pit ground-water monitoring wells are similar to those in the surrounding area. Detected chemical concentrations in water from the chromic acid pit monitoring wells during the four sampling periods were below U.S. Environmental Protection Agency-established maximum contaminant levels for public drinking water supplies. Statistical analyses were performed on 39 of the chemical constituents analyzed for in ground water from the chromic acid pit monitoring wells. Concentrations of chloride and fluoride were significantly less in water from the downgradient wells than in water from the upgradient well, whereas concentrations of nitrate as nitrogen, nitrite plus nitrate as nitrogen, and dissolved solids were significantly greater in water from the downgradient wells than in water from the upgradient well. Concentrations of nitrate as nitrogen were significantly different in water from the two downgradient wells. Differences detected through statistical analysis of chemical constituents of water in the chromic acid pit monitoring wells did not appear to indicate a release of hazardous chemicals from the chromic acid pit. There was no indication of ground-water contamination in either downgradient well.

Effluent migration from septic tank systems in two different lithologies, Broward County, Florida

USGS Publications Warehouse

Waller, B.G.; Howie, Barbara; Causaras, C.R.

1987-01-01

Two septic tank test sites, one in sand and one in limestone, in Broward County, Florida, were analyzed for effluent migration. Groundwater from shallow wells, both in background areas and hydraulically down-gradient of the septic tank system, was sampled during a 16-month period from April 1983 through August 1984. Water quality indicators were used to determine the effluent affected zone near the septic tank systems. Specific conductance levels and concentrations of chloride, sulfate, ammonium, and nitrate indicated effluent movement primarily in a vertical direction with abrupt dilution as it moved down-gradient. Effluent was detected in the sand to a depth more than 20 ft below the septic tank outlet, but was diluted to near background conditions 50 ft down-gradient from the tank. Effluent in the limestone was detected in all three observation wells to depths exceeding 25 ft below the septic tank outlet and was diluted, but still detectable, 40 ft down-gradient. The primary controls on effluent movement from septic tank systems in Broward County are the lithology and layering of the geologic materials, hydraulic gradients, and the volume and type of use the system receives. (Author 's abstract)

Effects of selected sources of contamination on ground-water quality at seven sites in Connecticut

USGS Publications Warehouse

Handman, Elinor H.; Bingham, James W.

1980-01-01

The introduction of contaminants has altered the quality of ground water at several places in Connecticut. This investigation of the hydrogeologic environment and the quality of water in stratified-drift aquifers underlying seven probable contaminant sources in Connecticut shows some effects at each site. Water from test wells downgradient from septage-disposal facilities in Old Saybrook and Clinton contains elevated concentrations of sodium, chloride, manganese, iron, detergent (as MBAS), dissolved organic carbon, and some trace metals. The effects are most pronounced at shallow depths close to the septage lagoons, where concentrations of some constituents exceed Connecticut Department of Health drinking water standards. Fly-ash disposal at Wallingford has contributed chromium, manganese, and dissolved organic carbon to water in the underlying aquifer, but the low hydraulic conductivity of the fine-grained surficial materials have kept effects to a minimum. Road salt leached from a storage area in the Tylerville section of Haddam has increased the sodium and chloride concentrations in ground water to the extent that it is unsuitable for drinking water. The effect diminishes in wells 1000 feet downgradient from the storage site. Water from some wells adjacent to landfills in Bristol and Southington has elevated sodium, chloride, manganese, and dissolved organic carbon concentrations, and samples from two wells near industrial-sludge disposal pits in the Bristol landfill contain cyanide and phenols. Gasoline odor is present in water samples from a test well 175 feet from a ruptured buried tank in Fairfield. The gasoline odor from this well was also detectable during well construction and sampling.

Effects of dried wastewater-treatment sludge application on ground-water quality in South Dade County, Florida

USGS Publications Warehouse

Howie, Barbara

1992-01-01

Four test fields in the south Dade agricultural area were studied to determine the effects of sludge application on ground-water quality. Two fields had been cultivated for 10 years or more, and two had not been farmed for at least 10 years. The fields were representative of the area's two soil types (Rockdale and Perrine marl) and two major crop types (row crops and groves). Before the application of sludge, wells upgradient of, within, and downgradient of each field were sampled for possible sludge contaminants at the end of wet and dry seasons. Municipal wastewater treatment sludge from the Dade County Water and Sewe Authority Department was then applied to the fields at varying application rates. The wells at each field were sampled over a 2-year period under different hydrologic conditions for possible sludge-related constituents (specific conductance, pH, alkalinity, nitrogen, phosphorus, total organic carbon, copper, iron, magnesium, manganese, potassium, zinc, arsenic, cadmium, chloride, chromium, lead, mercury, nickel, and sodium). Comparisons were made between water quality in the vicinity of the test fields and Florida Department of Environmental Regulation primary and secondary drinking-water regulations, an between water quality upgradient of, beneath, and downgradient of the fields. Comparisons between presludge and postsludge water quality did not indicate any improvement because of retention of agrichemicals by the sludge nor did they indicate any deterioration because of leaching from the sludge. Comparisons of water quality upgradient of the fields to water quality beneath and downgradient of the fields also did not indicate any changes related to sludge. Florida Department of Environmental Regulation primary and secondary drinking-water regulations wer exceeded at the Rockdale maximum-application field by mercury (9.5 ug/L (micrograms per liter)), and the Perrine marl maximum-application field by manganese (60 ug/L) and lead (85 ug/L), and at the Perrine marl row-crop field by mercury (5.2 ug/L). All other exceedances were either in presludge or upgradient samples, or they were for constituents or properties, such as iron and color, which typically exceed standards in native ground water. Acid-extractable and base-neutral compounds, volatile organic compounds, chlorophenoxy herbicides, organophosphorus insecticides, and organochlorine compounds were analyzed for one shallow well at each field twice annually. Those compounds that equaled or exceeded the detection limit after sludge was applied included benzene (0.3 and 1.2 ug/L), chloroform (0.2 and 0.3 ug/L), bis(2-Ethylhexyl)phthalate (29 and 42 ug/L), methylene chloride (14 ug/L), tolulene (0.2, 0.4, 0.5, 1.3, and 4.4 ug/L), 1, 1,1-trichloroethana (0.6 ug/L), trichloroethylene (0.3 ug/L), 2.4-D (0.01 ug/L), and xylene (0.3 ug/L). It ws not possible to ascertain the origin of these compounds becuase they are available from sources other than sludge.

Ground-water contamination and movement at the Defense General Supply Center, Richmond, Virginia. Water Resources Investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, J.D.; Wright, W.G.; Nelms, D.L.

1990-01-01

The report documents the efforts of the USGS in support of the quantification phase of the IRP to determine the degree of contamination of a site that has been identified as requiring study. The report describes the extent, concentration, direction, and rate of movement of contaminants in ground water beyond the boundaries of the DGSC. Hydrologic and geologic data were collected during 1984-90 from wells located upgradient from the DGSC, upgradient from the Area 50 landfill located on the DGSC, in the landfill, in the National Guard Area (NGA) downgradient from the landfill, and downgradient from the NGA beyond themore » eastern boundary of the DGSC. Lithologic data were collected during drilling of wells installed downgradient of the NGA by the USGS during 1984-86. Water from wells located downgradient of the NGA was analyzed for volatile-organic compounds, major cations and anions, priority-pollutant trace metals, and total organic carbon. Aquifer-test wells were installed by the USGS and aquifer testing was performed during 1985.« less

Geohydrology, simulation of ground-water flow, and ground-water quality at two landfills, Marion County, Indiana

USGS Publications Warehouse

Duwelius, R.F.; Greeman, T.K.

1989-01-01

Concentrations of dissolved inorganic substances in ground-water samples indicate that leachate from both landfills is reaching the shallow aquifers. The effect on deeper aquifers is small because of the predominance of horizontal ground-water flow and discharge to the streams. Increases in almost all dissolved constituents were observed in shallow wells that are screened beneath and downgradient from the landfills. Several analyses, especially those for bromide, dissolved solids, and ammonia, were useful in delineating the plume of leachate at both landfills.

US Environmental rotection Agency's strategy for ground-water-quality monitoring at hazardous-waste land-disposal facilities located in karst terranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, M.S.

1988-11-01

Ground-water monitoring of hazardous-waste land-disposal units by a network of wells is ineffective when located in karstic terranes. The U.S. Environmental Protection Agency (EPA) is currently proposing to modify its current ground-water-quality monitoring requirement of one upgradient well and three downgradient wells for disposal units located in karstic terranes. The convergent nature of subsurface flow to cave streams in karstic terranes requires that effective monitoring wells intercept the cave streams. Wells located around a hazardous-waste disposal unit, but not in the specific cave stream draining the site, are only providing irrelevant data and a false sense of security because themore » water samples from such wells are not necessarily from the hazardous-waste disposal unit. A case study is provided in this paper. EPA is drafting a guidance document that will allow monitoring by wells, only if the up- and down-gradient wells can be demonstrated to be hydraulically connected by means of dye-trace studies. If not, then the monitoring of springs shown to be hydraulically connected to the facility by dye-tracing studies would be required. Monitoring for sinkhole development will also be required to provide advance warning of sinkhole collapse. The investigation and determination of the probability of sinkhole collapse is given special treatment.« less

Ground-water quality near an inactive landfill and sludge-spreading area, Tallahassee, Florida

USGS Publications Warehouse

Berndt, M.P.

1993-01-01

Groundwater quality at and near a landfill southwest of Tallahassee, Florida, where sludge from a municipal sewage-treatment plant was also applied, was assessed by sampling 21 monitoring wells and analyzing for various constituents. Water quality in the Upper Floridan aquifer at the site was compared to the water quality of 20 background wells in Leon County. Water quality in all samples from wells at the site was evaluated in relation to the landfill and sludge-spreading and nonsludge- spreading areas. Results from nonparametric statistical tests showed that potassium and nitrate concentrations were significantly different in samples from the Upper Floridan aquifer at the site and in samples from background wells. Median potassium concentrations were 0.7 mg/L in samples collected at the site and 0.4 mg/L in samples collected from background wells, whereas median nitrate concentration was 6.48 mg/L at the site and 0.51 mg/L in background wells. Graphical comparison of concentration distributions in six categories of wells; upgradient, landfill, adjacent to the landfill, downgradient onsite, downgradient offsite, and from background wells in Leon County, indicated that sodium, bicarbonate, sulfate, iron, manganese, dissolved solids, and specific conductance had highest concentrations in water from wells within the landfill. Nitrate concentrations were lowest in samples from wells in the landfill compared to the other categories. Concentrations of trace metals and organic constituents were mostly below detection limits although State maximum contaminant levels of 1.0 microg/L for benzene and vinyl chloride and 3.0 microg/L for tetrachloroethene were exceeded in water from some wells. Nitrate and chloride concentrations were significantly different in sludge-spreading and nonsludge-spreading areas. Median nitrate and chloride concentrations of 6.9 microg/L and 2.9 microg/L were detected in groundwater in sludge-spreading areas compared to 1.1 mg/L and 1.8 mg/L in nonsludge-spreading areas.

Water-quality effects and characterization of indicators of onsite wastewater disposal systems in the east-central Black Hills area, South Dakota, 2006-08

USGS Publications Warehouse

Putnam, Larry D.; Hoogestraat, Galen K.; Sawyer, J. Foster

2008-01-01

Onsite wastewater disposal systems (OWDS) are used extensively in the Black Hills of South Dakota where many of the watersheds and aquifers are characterized by fractured or solution-enhanced bedrock with thin soil cover. A study was conducted during 2006-08 to characterize water-quality effects and indicators of OWDS. Water samples were collected and analyzed for potential indicators of OWDS, including chloride, bromide, boron, nitrite plus nitrate (NO2+NO3), ammonia, major ions, nutrients, selected trace elements, isotopes of nitrate, microbiological indicators, and organic wastewater compounds (OWCs). The microbiological indicators were fecal coliforms, Escherichia coli (E. coli), enterococci, Clostridium perfringens (C. perfringens), and coliphages. Sixty ground-water sampling sites were located either downgradient from areas of dense OWDS or in background areas and included 25 monitoring wells, 34 private wells, and 1 spring. Nine surface-water sampling sites were located on selected streams and tributaries either downstream or upstream from residential development within the Precambrian setting. Sampling results were grouped by their hydrogeologic setting: alluvial, Spearfish, Minnekahta, and Precambrian. Mean downgradient dissolved NO2+NO3 concentrations in ground water for the alluvial, Spearfish, Minnekahta, and Precambrian settings were 0.734, 7.90, 8.62, and 2.25 milligrams per liter (mg/L), respectively. Mean downgradient dissolved chloride concentrations in ground water for these settings were 324, 89.6, 498, and 33.2 mg/L, respectively. Mean downgradient dissolved boron concentrations in ground water for these settings were 736, 53, 64, and 43 micrograms per liter (ug/L), respectively. Mean dissolved surface-water concentrations for NO2+NO3, chloride, and boron for downstream sites were 0.222 mg/L, 32.1 mg/L, and 28 ug/L, respectively. Mean values of delta-15N and delta-18O (isotope ratios of 14N to 15N and 18O to 16O relative to standard ratios) for nitrate in ground-water samples were 10.4 and -2.0 per mil (0/100), respectively, indicating a relatively small contribution from synthetic fertilizer and probably a substantial contribution from OWDS. The surface-water sample with the highest dissolved NO2+NO3 concentration of 1.6 mg/L had a delta-15N value of 12.36 0/100, which indicates warm-blooded animals (including humans) as the nitrate source. Fecal coliforms were detected in downgradient ground water most frequently in the Spearfish (19 percent) and Minnekahta (9.7 percent) settings. E. coli was detected most frequently in the Minnekahta (29 percent) and Spearfish (13 percent) settings. Enterococci were detected more frequently than other microbiological indicators in all four settings. Fecal coliforms and E. coli were detected in 73 percent and 95 percent of all surface-water samples, respectively. Enterococci, coliphages (somatic), and C. perfringens were detected in 50, 70, and 50 percent of surface-water samples, respectively. Of the 62 OWC analytes, 12 were detected only in environmental samples, 10 were detected in at least one environmental and one blank sample (not necessarily companion pairs), 2 were detected only in blank samples, and 38 were not detected in any blank, environmental, or replicate sample from either ground or surface water. Eleven different organic compounds were detected in ground-water samples at eight different sites. The most frequently occurring compound was DEET, which was found in 32 percent of the environmental samples, followed by tetrachloroethene, which was detected in 20 percent of the samples. For surface-water samples, 16 organic compounds were detected in 9 of the 10 total samples. The compound with the highest occurrence in surface-water samples was camphor, which was detected in 50 percent of samples. The alluvial setting was characterized by relatively low dissolved NO2+NO3 concentrations, detection of ammonia nitrogen, and relatively high concentr

Chemical quality of ground water in Salt Lake Valley, Utah, 1969-85

USGS Publications Warehouse

Waddell, K.M.; Seiler, R.L.; Solomon, D.K.

1986-01-01

During 1979-84, 35 wells completed in the principal aquifer in the Salt Lake Valley, Utah, that had been sampled during 1962-67 were resampled to determine if water quality changes had occurred. The dissolved solids concentration of the water from 13 of the wells has increased by more than 10% since 1962-67. Much of the ground water between the mouth of Bingham Canyon and the Jordan River about 10 mi to the east has been contaminated by seepage from reservoirs and evaporation ponds associated with mining activities. Many domestic and irrigation wells yield water with concentrations of dissolved solids that exceed 2,000 mg/L. A reservoir in the mouth of Bingham Canyon contains acidic waters with a pH of 3 to 4 and concentrations of dissolved solids ranging from 43,000 to 68,000 mg/L. Seepage from evaporation ponds, which are about 4.5 mi east of the reservoir, also is acidic and contains similar concentrations of dissolved solids. East of the reservoir, where a steep hydraulic gradient exists along the mountain front, the velocities of contaminant movement were estimated to range from about 680-1,000 ft/yr. Groundwater underlying part of the community of South Salt Lake near the Jordan River has been contaminated by leachate from uranium-mill tailings. The major effect of the leachate from the tailings of the Vitro Chemical Co. on the shallow unconfined aquifer downgradient from the tailings was the contribution of measurable quantities of dissolved solids, chloride, sulfate, iron, and uranium. The concentration of dissolved solids in uncontaminated water was 1,650 mg/L, whereas downgradient from the tailings area, the concentrations ranged from 2,320-21,000 mg/L. The maximum volume of contaminated water was estimated to be 7,800 acre-ft. The major effect of the leachate from the Vitro tailings on the confined aquifer was the contribution of measurable quantities of dissolved solids, chloride, sulfate, and iron. The concentration of dissolved solids upgradient from the tailings was 330 mg/L, and beneath and downgradient from the tailings the concentrations were 864 and 1,240 mg/L. The minimum volume of contaminated water in the confined aquifer was estimated to be about 12,000 acre-ft. (Lantz-PTT)

Using chemical and microbiological indicators to track the impacts from the land application of treated municipal wastewater and other sources on groundwater quality in a karstic springs basin

NASA Astrophysics Data System (ADS)

Katz, Brian G.; Griffin, Dale W.

2008-08-01

Multiple chemical constituents (nutrients; N, O, H, C stable isotopes; 64 organic wastewater compounds, 16 pharmaceutical compounds) and microbiological indicators were used to assess the impact on groundwater quality from the land application of approximately 9.5 million liters per day of treated municipal sewage effluent to a sprayfield in the 960-km2 Ichetucknee Springs basin, northern Florida. Enriched stable isotope signatures (δ18O and δ2H) were found in water from the effluent reservoir and a sprayfield monitoring well (MW-7) due to evaporation; however, groundwater samples downgradient from the sprayfield have δ18O and δ2H concentrations that represented recharge of meteoric water. Boron and chloride concentrations also were elevated in water from the sprayfield effluent reservoir and MW-7, but concentrations in groundwater decreased substantially with distance downgradient to background levels in the springs (about 12 km) and indicated at least a tenfold dilution factor. Nitrate-nitrogen isotope (δ15N NO3) values above 10 ‰ in most water samples were indicative of organic nitrogen sources except Blue Hole Spring (δ15N NO3 = 4.6 4.9 ‰), which indicated an inorganic source of nitrogen (fertilizers). The detection of low concentrations the insect repellent N, N-diethyl-metatoluamide (DEET), and other organic compounds associated with domestic wastewater in Devil’s Eye Spring indicated that leakage from a nearby septic tank drainfield likely has occurred. Elevated levels of fecal coliforms and enterococci were found in Blue Hole Spring during higher flow conditions, which likely resulted from hydraulic connections to upgradient sinkholes and are consistent with previoius dye-trace studies. Enteroviruses were not detected in the sprayfield effluent reservoir, but were found in low concentrations in water samples from a downgradient well and Blue Hole Spring during high-flow conditions indicating a human wastewater source. The Upper Floridan aquifer in the Ichetucknee Springs basin is highly vulnerable to contamination from multiple anthropogenic sources throughout the springs basin.

Using chemical and microbiological indicators to track the impacts from the land application of treated municipal wastewater and other sources on groundwater quality in a karstic springs basin

USGS Publications Warehouse

Katz, B.G.; Griffin, Dale W.

2008-01-01

Multiple chemical constituents (nutrients; N, O, H, C stable isotopes; 64 organic wastewater compounds, 16 pharmaceutical compounds) and microbiological indicators were used to assess the impact on groundwater quality from the land application of approximately 9.5 million liters per day of treated municipal sewage effluent to a sprayfield in the 960-km2 Ichetucknee Springs basin, northern Florida. Enriched stable isotope signatures (?? 18O and ??2H) were found in water from the effluent reservoir and a sprayfield monitoring well (MW-7) due to evaporation; however, groundwater samples downgradient from the sprayfield have ??18O and ??2H concentrations that represented recharge of meteoric water. Boron and chloride concentrations also were elevated in water from the sprayfield effluent reservoir and MW-7, but concentrations in groundwater decreased substantially with distance downgradient to background levels in the springs (about 12 km) and indicated at least a tenfold dilution factor. Nitrate-nitrogen isotope (??15N-NO3) values above 10 ??? in most water samples were indicative of organic nitrogen sources except Blue Hole Spring (??15N-NO3 = 4.6-4.9 ???), which indicated an inorganic source of nitrogen (fertilizers). The detection of low concentrations the insect repellent N,N-diethyl-metatoluamide (DEET), and other organic compounds associated with domestic wastewater in Devil's Eye Spring indicated that leakage from a nearby septic tank drainfield likely has occurred. Elevated levels of fecal coliforms and enterococci were found in Blue Hole Spring during higher flow conditions, which likely resulted from hydraulic connections to upgradient sinkholes and are consistent with previoius dye-trace studies. Enteroviruses were not detected in the sprayfield effluent reservoir, but were found in low concentrations in water samples from a downgradient well and Blue Hole Spring during high-flow conditions indicating a human wastewater source. The Upper Floridan aquifer in the Ichetucknee Springs basin is highly vulnerable to contamination from multiple anthropogenic sources throughout the springs basin. ?? 2007 Springer-Verlag.

Geochemical and microbiological assessment of groundwater status: a case study

NASA Astrophysics Data System (ADS)

Preziosi, E.; Del Bon, A.; Amalfitano, S.; Fazi, S.; Zoppini, A.; Parrone, D.; Ghergo, S.

2012-04-01

The qualitative status of the groundwater resources is drawing increasingly attention in relation to the requirements of the European legislative framework. The monitoring strategies are developed by considering the chemical processes affecting groundwater quality. However, despite the use of biological indicators is a common practice for the qualitative assessment of surface waters, a similar approach is hardly being taken into account by policy makers for ground waters. Aquifers are key environments due to the ecosystem capability to ameliorate water quality, e.g. through the natural biodegradation of chemical contaminants. The objective of this research was to characterize a porous water table aquifer from a geochemical and microbiological point of view, aiming to link the hydrogeochemical properties to distribution patterns of the free-living microbial communities. The broader perspective is to integrate the role of microorganisms in the groundwater evolution processes, with new insights in the knowledge of the different microbial communities inhabiting different aquifer typologies. Moreover, microbiological parameters that could be used as a valuable indicator of groundwater quality are sought. A field-scale analysis was performed along the southern Sabatini Mounts aquifer (Central Italy, 50 sampling sites), in an area of about 340 square km, where Pleistocene volcanic products overlay Pleistocene gravel and silt-clay layers, the latter being much more widespread in the downgradient part of the study area. The selected aquifer is contaminated by natural origin elements such as arsenic and fluoride, as well as by human activities, both diffuse (agriculture) and localized, especially in the downgradient part of the aquifer (e.g. landfills, quarries, oil deposits). The main physicochemical parameters of ground waters were determined in situ (redox status, pH, conductivity, T, DO, alkalinity) and in laboratory by ionic chromatography and mass spectrometry (major and trace elements, including arsenic). Total bacterial abundance and vitality (live/dead cell ratio) was determined by combining Flow Cytometry with a double staining fluorescence assay, while the microbial community composition was analyzed through hybridization techniques (CARD-FISH). The hydrogeochemical characterization defined an arsenic rich, mainly alkaline-earth bicarbonate type, which evolves downgradiently towards a more calcium rich water. The variability of bacterial abundance was nonetheless high and the percentage of dead bacterial cells shows a significant correlation with the arsenic concentration. In addition, differences of the taxa along the flow path were detected with an increasing abundance of Delta-Proteobacteria in the more anoxic sites. Overall, our results highlighted that a multidisciplinary approach, which combines geochemical and microbiological surveys, can describe more appropriately ground water status and the evolution processes in the aquifer.

Dichlorobenzene in ground water: Evidence for long-term persistence

USGS Publications Warehouse

Barber, L.B.

1988-01-01

Hydrologic and geochemical evidence were used to establish the long-term persistence of dichlorobenzene in ground water that has been contaminated from 50 years of rapid-infiltration sewage disposal. An extensive plume of dichlorobenzene extends more than 3,500 meters downgradient from the disposal beds, with concentrations of the combined isomers ranging from less than 0.01 to over 1.0 ??g/l. Based on estimates of maximum ground-water flow velocities, a minimum age of 20 years was established for the farthest downgradient zone of dichlorobenzene contamination. Branched-chained, alkylbenzenesulfonic acid surfactants, that were introduced into the ground water prior to 1966, occur along with dichlorobenzene in the downgradient part of the plume, further establish residence of the compounds in the aquifer for at least 20 years. Although dichlorobenzene can be biologically degraded under aerobic conditions, its persistence at this field site is attributed to the dynamics of the ground-water system. Denitrifying conditions, resulting from the degradation of organic compounds in the aquifer near the disposal beds, appear to have enhanced the persistence of dichlorobenzene, which is not degraded by anaerobic bacteria. Biological degradation of dichlorobenzene in the aerobic part of the plume downgradient from the source is probably limited by the paucity of a suitable organic-carbon substrate and the low concentrations of dissolved oxygen in the contaminated ground water.

Herbicide loading to shallow ground water beneath Nebraska's Management Systems Evaluation Area.

PubMed

Spalding, Roy F; Watts, Darrell G; Snow, Daniel D; Cassada, David A; Exner, Mary E; Schepers, James S

2003-01-01

Better management practices can counter deterioration of ground water quality. From 1991 through 1996 the influence of improved irrigation practices on ground water pesticide contamination was assessed at the Nebraska Management Systems Evaluation Area. Three 13.4-ha corn (Zea mays L.) fields were studied: a conventional furrow-irrigated field, a surge-irrigated field and a center pivot-irrigated field, and a center pivot-irrigated alfalfa (Medicago sativa L.) field. The corn fields received one identical banded application of Bicep (atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4,-diamine] + metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamidel) annually; the alfalfa field was untreated. Ground water samples were collected three times annually from 16 depths of 31 multilevel samplers. Six years of sample data indicated that a greater than 50% reduction in irrigation water on the corn management fields lowered average atrazine concentrations in the upper 1.5 m of the aquifer downgradient of the corn fields from approximately 5.5 to <0.5 microg L(-1). Increases in deethylatrazine (DEA; 2-chloro-4-amino-6-isopropylamino-s-triazine) to atrazine molar ratios indicated that reducing water applications enhanced microbial degradation of atrazine in soil zones. The occurrence of peak herbicide loading in ground water was unpredictable but usually was associated with heavy precipitation within days of herbicide application. Focused recharge of storm runoff that ponded in the surge-irrigated field drainage ditch, in the upgradient road ditch, and at the downgradient end of the conventionally irrigated field was a major mechanism for vertical transport. Sprinkler irrigation technology limited areas for focused recharge and promoted significantly more soil microbial degradation of atrazine than furrow irrigation techniques and, thereby, improved ground water quality.

Geophysical and hydrogeological characterisation of the impacts of on-site wastewater treatment discharge to groundwater in a poorly productive bedrock aquifer.

PubMed

Donohue, Shane; McCarthy, Valerie; Rafferty, Patrick; Orr, Alison; Flynn, Raymond

2015-08-01

Contaminants discharging from on-site wastewater treatment systems (OSWTSs) can impact groundwater quality, threatening human health and surface water ecosystems. Risk of negative impacts becomes elevated in areas of extreme vulnerability with high water tables, where thin unsaturated intervals limit vadose zone attenuation. A combined geophysical/hydrogeological investigation into the effects of an OSWTS, located over a poorly productive aquifer (PPA) with thin subsoil cover, aimed to characterise effluent impacts on groundwater. Groundwater, sampled from piezometers down-gradient of the OSWTS percolation area displayed spatially erratic, yet temporally consistent, contaminant distributions. Electrical resistivity tomography identified an area of gross groundwater contamination close to the percolation area and, when combined with seismic refraction and water quality data, indicated that infiltrating effluent reaching the water table discharged to a deeper more permeable zone of weathered shale resting on more competent bedrock. Subsurface structure, defined by geophysics, indicated that elevated chemical and microbiological contaminant levels encountered in groundwater samples collected from piezometers, down-gradient of sampling points with lower contaminant levels, corresponded to those locations where piezometers were screened close to the weathered shale/competent rock interface; those immediately up-gradient were too shallow to intercept this interval, and thus the more impacted zone of the contaminant plume. Intermittent occurrence of faecal indicator bacteria more than 100m down gradient of the percolation area suggested relatively short travel times. Study findings highlight the utility of geophysics as part of multidisciplinary investigations for OSWTS contaminant plume characterisation, while also demonstrating the capacity of effluent discharging to PPAs to impact groundwater quality at distance. Comparable geophysical responses observed in similar settings across Ireland suggest the phenomena observed in this study are more widespread than previously suspected. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrogeologic and water-quality data from well clusters near the wastewater-treatment plant, U.S. Marine Corps Air Station, Cherry Point, North Carolina

USGS Publications Warehouse

Murray, L.C.; Daniel, C. C.

1990-01-01

Hydrogeologic and ground-water quality data were collected near the wastewater-treatment plant and associated polishing lagoons at the Marine Corps Air Station, Cherry Point, North Carolina, in 1988. Between March and May 1988, two observation wells were installed upgradient and six wells were installed downgradient of the polishing lagoons and sampled for organic and inorganic U.S. Environmental Protection Agency priority pollutants. Placement of the well screens allowed sampling from both the upper and lower parts of the surficial aquifer. Natural gamma-ray geophysical logs were run in the four deepest wells. Lithologic logs were prepared from split-spoon samples collected during the drilling operations. Laboratory hydraulic conductivity tests were conducted on samples of fine-grained material recovered from the two confining units that separate the surficial aquifer and the drinking-water supply aquifer; values ranged from 0.011 to 0.014 foot per day (4x10-6 to 5x10-6 centimeters per second). Static water levels were recorded on April 25, 1988. Relatively low concentrations of purgeable organic compounds (up to 2.2 micrograms per liter for dichlorodifluoromethane), acid and base/neutral extractable compounds (up to 58 micrograms per liter for bis(2-ethylhexyl) phthalate), or pesticides (up to 0.03 micrograms per liter for diazinon and methyl parathion) were detected in water samples collected from all of the wells. Trace metals were detected in concentrations above minimum detectable limits in all of the wells and were found to be higher in water samples collected from the downgradient wells (up to 320 micrograms per liter for zinc) than in water samples from the upgradient wells.

An evaluation of the results of alluvial groundwater sampling from 1987--1990 at the Durango disposal site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-04-01

This evaluation was conducted to determine if surface discharges of contaminated water from a retention pond and seepage of tailings pore water from the disposal cell have affected ground I water quality in the alluvial deposits east and northeast of the Bodo Canyon disposal cell. The question of whether corrective remedial action is needed for the alluvial groundwater downgradient of the disposal cell is also addressed. Maximum observed concentrations of seven hazardous constituents equalled or exceeded proposed US Environmental Protection Agency (EPA) maximum concentration limits (MCLs) in the alluvial groundwater downgradient of the disposal cell. These constituents include chromium, lead,more » molybdenum, net gross alpha, radium-226 and -228, selenium, and uranium. Concentrations greater than MCLs for molybdenum, net gross alpha, and radium-226 and -228 may be naturally occurring in the alluvial groundwater. There is no statistical evidence that these hazardous constituents are groundwater contaminants with concentrations that exceed the MCLs in alluvial groundwater. However, the median selenium concentration in monitor well 608 exceeds the MCL. Therefore, selenium contamination in the alluvial groundwater in the area of monitor well 608 is possible. Selenium concentrations show no definite increasing or decreasing trend. Since groundwater contamination by selenium is possible in one monitor well, but concentrations are not increasing, corrective action is not warranted at this time. Alluvial groundwater quality will continue to be monitored quarterly and the discharge from the retention pond should be sampled after treatment to ascertain its potential affects on groundwater quality.« less

Ground-water quality near a sewage-sludge recycling site and a landfill near Denver, Colorado

USGS Publications Warehouse

Robson, Stanley G.

1977-01-01

The Metropolitan Denver Sewage Disposal District and the City and County of Denver operate a sewage-sludge recycling site and a landfill in an area about 15 miles (24 kilometers) east of Denver. The assessment of the effects of these facilities on the ground-water system included determining the direction of ground-water movement in the area, evaluating the impact of the wastedisposal activities on the chemical quality of local ground water, and evaluating the need for continued water-quality monitoring.Surficial geology of the area consists of two principal units: (1) Alluvium with a maximum thickness of about 25 feet (7.6 meters) deposited along stream channels, and (2) bedrock consisting of undifferentiated Denver and Dawson Formations. Ground water in formations less than 350 feet (110 meters) deep moves to the north, as does surface flow, while ground water in formations between 570 and 1,500 feet (170 and 460 meters) deep moves to the west. Estimates of ground-water velocity were made using assumed values for hydraulic conductivity and porosity, and the observed hydraulic gradient from the study area. Lateral velocities are estimated to be 380 feet (120 meters) per year in alluvium and 27 feet (8.2 meters) per year in the upper part of the bedrock formations. Vertical velocity is estimated to be 0.58 foot (0.18 meter) per year in the upper part of the bedrock formations.Potentiometric head decreases with depth in the bedrock formations indicating a potential for downward movement of ground water. However, waterquality analysis and the rate and direction of ground-water movement suggest that ground-water movement in the area is primarily in the lateral rather than the vertical direction. Five wells perforated in alluvium were found to have markedly degraded water quality. One well was located in the landfill and water that was analyzed was obtained from near the base of the buried refuse, two others were located downgradient and near sewage-sludge burial areas, and the remaining two are located near stagnant surface ponds. Concentrations of nitrate in wells downgradient from fields where sludge is plowed into the soil were higher than background concentrations due to the effects of the sludge disposal. No evidence of water-quality degradation was detected in deeper wells perforated in the bedrock formations. Continued water-quality monitoring is needed because of the continuing disposal of wastes. A suggested monitoring program would consist of monitoring wells near the landfill twice a year and monitoring wells near the sludge-disposal areas on an annual basis.

Buffer zone monitoring plan for the Dos Rios subdivision, Gunnison, Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1996-02-01

This report presents a plan for water quality monitoring at the Dos Rios subdivision (Units 2, 3, and the Island Unit) that is intended to satisfy the informational needs of residents who live southwest (downgradient) of the former Gunnison processing site. Water quality monitoring activities described in this report are designed to protect the public from residual contamination that entered the ground water as a result of previous uranium milling operations. Requirements presented in this monitoring plan are also included in the water sampling and analysis plan (WSAP) for the Gunnison Uranium Mill Tailings Remedial Action (UMTRA) Project site. Themore » Gunnison WSAP is a site-specific document prepared by the U.S. Department of Energy (DOE) that provides background, guidance, and justification for future ground water sampling and analysis activities for the UMTRA Project Gunnison processing and disposal sites. The WSAP will be updated annually, as additional water quality data are collected and interpreted, to provide ongoing protection for public health and the environment.« less

Results of testing landspreading of treated municipal wastewater at St. Petersburg, Florida

USGS Publications Warehouse

Reichenbaugh, R.C.; Brown, David P.; Goetz, Carole L.

1979-01-01

Chlorinated secondary-treated effluent was used to irrigate a grassed 4-acre site at rates of 2 and 4 inches per week for periods of 11 and 14 weeks, respectively. Part of the site was drained by tile lines 5 feet below land surface. Irrigation of the drained plot resulted in rapid passage of the applied wastewater through the soil and, consequently, poor nitrogen removal. The rapid percolation permitted nitrification but prevented denitrification. Total phosphorus in the shallow ground water at the site increased from a maximum of 1.4 milligrams per liter before irrigation to as much as 5 milligrams per liter in the ground water 5 feet below land surface. Concentrations of nitrogen and phosphorus did not increase in ground water downgradient from the site, although increased chloride concentrations demonstrated downgradient migration of the applied wastewater. Prior to irrigation, total coliform bacteria were not detected in ground water at the site. After irrigation, total and fecal coliforms were detected in the ground water at the site and downgradient. (Woodard-USGS)

Hydrogeology and effects of landfills on ground-water quality, southern Franklin County, Ohio

USGS Publications Warehouse

De Roche, J.T.

1985-01-01

Hydrogeology and water quality were evaluated near five land-fills along a 5-mile segment of the Scioto River valley south of Columbus, Ohio. Heterogenous surficial deposits o sand, gravel, and till up to 160 feet thick are hydraulically connected to the underlying Devonian limestone, the landfills and Scioto River, which has been leveed with 12 to 35 feet of refuse. Ground-water withdrawals caused a maximum 21-foot decline in ground-water levels from 1979 to 1982. The study reach of Scioto River within the influence of ground-water pumping is a losing stream, except for s small segment adjacent to one landfill. Analysis of variance indicated significant difference in ground-water quality between wells upgradient of landfills, down-gradient of landfills, and wells penetrating refuse. Elevated specific conductance and concentrations of total dissolved solids, ammonia, carbon dioxide, and dissolved organic carbon in water from wells downgradient from and penetrating landfills indicate leachate production and migration is occurring. Analysis of bed-material samples from Scioto River and Scioto Big Run revealed concentrations of polynuclear aromatic hydrocarbons ranging from 220 to 9,440 micograms per kilogram of sediment (?g/kg) and concentrations of toxic metals ranging from 1 to 720 ?g/kg. Samples from an upstream control station on Scioto River contained no organic compounds and lower concentrations of metals (ranging from 1 to 260 ?g/kg). Because of multiple land uses within the study area, organic compounds recovered from the streamed sediments cannot be attributed to any single source. The generation of hydrogen sulfide and methane gases, presence of a zone of increased hardness, elevated concentrations of common ionic species, and dominance of ammonia over other nitrogen species indicate that leachate is being produced and its migrating from four landfills and the river levee. Based on hydraulic relationships between ground water and surface water, it is highly probable that ground water contaminated by leachate from the levee and from one of the landfills is discharging to Scioto River. Leachate-enriched groundwater from other landfills also may begin to discharge to the river if water-withdrawal patterns in the study area change.

Arsenic and metallic trace elements cycling in the surface water-groundwater-soil continuum down-gradient from a reclaimed mine area: Isotopic imprints

NASA Astrophysics Data System (ADS)

Khaska, Mahmoud; Le Gal La Salle, Corinne; Sassine, Lara; Cary, Lise; Bruguier, Olivier; Verdoux, Patrick

2018-03-01

One decade after closure of the Salsigne mine (SW France), As contamination persisted in surface water, groundwater and soil near and down-gradient from the reclaimed ore processing site (OPS). We assess the fate of As and other associated chalcophilic MTEs, and their transport in the surface-water/groundwater/soil continuum down-gradient from the reclaimed OPS, using Sr-isotopic fingerprinting. The Sr-isotope ratio was used as a tracer of transfer processes in this hydro-geosystem and was combined to sequential extraction of soil samples to evaluate the impact of contaminated soil on the underlying phreatic groundwater. The contrast in Sr isotope compositions of the different soil fractions reflects several Sr sources in the soil. In the complex hydro-geosystem around the OPS, the transport of As and MTEs is affected by a succession of factors, such as (1) Existence of a reducing zone in the aquifer below the reclaimed OPS, where groundwater shows relatively high As and MTEs contents, (2) Groundwater discharge into the stream near the reclaimed OPS causing an increase in As and MTE concentrations in surface water; (3) Partial co-precipitation of As with Fe-oxyhydroxides, contributing to some attenuation of As contents in surface water; (4) Infiltration of contaminated stream water into the unconfined aquifer down-gradient from the reclaimed OPS; (5) Accumulation of As and MTEs in soil irrigated with contaminated stream- and groundwater; (6) Release of As and MTEs from labile soil fractions to underlying the groundwater.

Effects of drain wells on the ground-water quality of the western Snake Plain Aquifer, Idaho

USGS Publications Warehouse

Moreland, Joe A.; Seitz, Harold R.; LaSala, Albert Mario

1976-01-01

Approximately 3,100 drain wells injects irrigation waste water, urban runoff, septic-tank effluent, and industrial waste water into the Snake Plain aquifer in Minidoka, Gooding, Jerome, and Lincoln Counties, Idaho. About 29,000 acre-feet of irrigation waste water, 100 acre-feet of urban runoff, 400 acre-feet of septic-tank effluent, and 1,000 acre-feet of industrial waste water are injected annually. The quality of irrigation waste water is highly variable, depending upon its source, method and rate of application, amount of fertilizer added, and other factors. The quality of urban runoff water is generally much better than irrigation waste water. Septic-tank effluent is relatively high in nutrient concentrations. Chloride concentrations also are high, and bacterial concentrations are exceedingly high. The only industrial waste water sampled during this study had been used for cooling. No chemical changes were noted, but temperature was significantly increased. The data indicate that drain-well inflow does move appreciable distances through the aquifer and can be detected in downgradient wells. (Woodard-USGS)

Effects of highway-deicer application on ground-water quality in a part of the Calumet Aquifer, northwestern Indiana

USGS Publications Warehouse

Watson, Lee R.; Bayless, E. Randall; Buszka, Paul M.; Wilson, John T.

2002-01-01

The effects of highway-deicer application on ground-water quality were studied at a site in northwestern Indiana using a variety of geochemical indicators. Site characteristics such as high snowfall rates; large quantities of applied deicers; presence of a high-traffic highway; a homogeneous, permeable, and unconfined aquifer; a shallow water table; a known ground-water-flow direction; and minimal potential for other sources of chloride and sodium to complicate source interpretation were used to select a study area where ground water was likely to be affected by deicer application. Forty-three monitoring wells were installed in an unconfined sand aquifer (the Calumet aquifer) near Beverly Shores in northwestern Indiana. Wells were installed along two transects that approximately paralleled groundwater flow in the Calumet aquifer and crossed US?12. US?12 is a highway that receives Indiana?s highest level of maintenance to maintain safe driving conditions. Ground-water quality and water-level data were collected from the monitoring wells, and precipitation and salt-application data were compiled from 1994 through 1997. The water-quality data indicated that chloride was the most easily traced indicator of highway deicers in ground water. Concentration ratios of chloride to iodide and chloride to bromide and Stiff diagrams of major element concentrations indicated that the principal source of chloride and sodium in ground water from the uppermost one-third to one-half of the Calumet relative electromagnetic conductivity defined a distinct plume of deicer-affected water in the uppermost 8 feet of aquifer at about 9 feet horizontally from the paved roadway edge and a zone of higher conductivity than background in the lower one-third of the aquifer. Chloride and sodium in the deep parts of the aquifer originated from natural sources. Chloride and sodium from highway deicers were present in the aquifer throughout the year. The highest concentrations of chloride and sodium in ground water were determined in samples collected during the spring and summer from wells open to the water table within about 9 feet of the highway. Chloride concentrations in ground water that were attributable to highway deicers also were found in tested wells about 400 feet downgradient from US?12 during the fall and winter and at greater depths than in wells closer to US?12. Chloride concentrations exceeded the U.S. Environmental Protection Agency?s (USEPA) secondary maximum contaminant level of 250 milligrams per liter for drinking water at seven wells downgradient from the highway during late winter, spring, and summer samplings. The chloride standard was exceeded only in water from wells with total depths that are less than about 10 feet below land surface. Sodium concentrations in water periodically exceeded the USEPA drinking-water equivalency level of 20 milligrams per liter in both the uppermost (deicer affected) and lower one-thirds of the aquifer. Sodium concentrations in ground water downgradient from US?12 and in the upper 5 feet of the aquifer also occasionally exceeded drinking-water standards for sodium (160 milligrams per liter) as set by the State of Florida and a standard for taste (200 milligrams per liter) as set by the World Health Organization. Dispersion was identified by analysis of aquifer-test data, isotopic dating of ground water, and water-quality data to be the process most responsible for reducing concentrations of highway deicers in the aquifer. Chemical analyses of the sand composing the aquifer indicated that cation exchange decreased the mass of deicer-related sodium in ground water, although the sand has a limited capacity to sustain the process. Automated daily measurements of specific conductance, correlated to chloride concentrations, indicated that some deicer is retained in the aquifer near the highway throughout the entire year and acts as a continuous chloride source for ground water. Peak concentrations of

Geochemical processes in ground water resulting from surface mining of coal at the Big Sky and West Decker Mine areas, southeastern Montana

USGS Publications Warehouse

Clark, D.W.

1995-01-01

A potential hydrologic effect of surface mining of coal in southeastern Montana is a change in the quality of ground water. Dissolved-solids concen- trations in water in spoils aquifers generally are larger than concentrations in water in the coal aquifers they replaced; however, laboratory experiments have indicated that concentrations can decrease if ground water flows from coal-mine spoils to coal. This study was conducted to determine if decreases in concentrations occur onsite and, if so, which geochemical processes caused the decreases. Solid-phase core samples of spoils, unmined over- burden, and coal, and ground-water samples were collected from 16 observation wells at two mine areas. In the Big Sky Mine area, changes in ground- water chemistry along a flow path from an upgradient coal aquifer to a spoils aquifer probably were a result of dedolomitization. Dissolved-solids concentrations were unchanged as water flowed from a spoils aquifer to a downgradient coal aquifer. In the West Decker Mine area, dissolved-solids concentrations apparently decreased from about 4,100 to 2,100 milligrams per liter as water moved along an inferred flow path from a spoils aquifer to a downgradient coal aquifer. Geochemical models were used to analyze changes in water chemistry on the basis of results of solid-phase and aqueous geochemical characteristics. Geochemical processes postulated to result in the apparent decrease in dissolved-solids concentrations along this inferred flow path include bacterial reduction of sulfate, reverse cation exchange within the coal, and precipitation of carbonate and iron-sulfide minerals.

Redox conditions and the efficiency of chlorinated ethene biodegradation: Field studies

USGS Publications Warehouse

Chapelle, F.H.; Bradley, P.M.

2000-01-01

The effect of redox conditions on the efficiency of chlorinated ethene biodegradation was investigated at two field sites. One site (NAS Cecil Field, FL) is characterized by predominantly Fe(III)-reducing conditions in the contaminant source area, grading to predominantly sulfate- reducing conditions downgradient. This sequence of redox conditions led to relatively inefficient biodegradation of chlorinated ethenes, with high concentrations of trichloroethene extending more than 400 meters downgradient of the source area. In contrast, a second site (NBS Kings Bay, GA) characterized by predominantly sulfate-reducing conditions in the source area followed by Fe(III)-reducing conditions downgradient. In this system perchloroethene (PCE) and TCE were rapidly biodegraded and extended less than 100 meters downgradient. Rates of ground- water transport are similar at the two sites (???0.2 m/d) indicating that the succession of redox processes, rather than other hydrologic factors, is the principal control on biodegradation. In particular, redox conditions that favor the initial reduction of highly chlorinated ethenes (methanogenic or sulfate-reducing conditions) followed by more oxidizing conditions (Fe(III)- reducing or oxic conditions) favors efficient biodegradation. Thus, documenting the succession of redox processes is an important step in understanding the efficiency of chlorinated ethene biodegradation in ground-water systems.

Plume persistence caused by back diffusion from thin clay layers in a sand aquifer following TCE source-zone hydraulic isolation.

PubMed

Parker, Beth L; Chapman, Steven W; Guilbeault, Martin A

2008-11-14

This paper concludes that back diffusion from one or a few thin clayey beds in a sand aquifer can cause contaminant persistence above MCLs in a sand aquifer long after the source zone initially causing the plume is isolated or removed. This conclusion is based on an intensive case study of a TCE contaminated site in Florida, with the processes evaluated using numerical modeling. At this site, the TCE DNAPL zone formed decades ago, and was hydraulically isolated by means of an innovative system performing groundwater extraction, treatment and re-injection. Treated water is re-injected in a row of injection wells situated a short distance downgradient of the extraction wells, creating a clean-water displacement front to efficiently flush the downgradient plume. This scheme avoids the creation of stagnation zones typical of most groundwater pump-and-treat systems, thereby minimizing the time for aquifer flushing and therefore downgradient cleanup. The system began operation in August 2002 and although the performance monitoring shows substantial declines in concentrations, detectable levels of TCE and degradation products persist downgradient of the re-injection wells, long after the TCE should have disappeared based on calculations assuming a nearly homogenous sand aquifer. Three hypotheses were assessed for this plume persistence: 1) incomplete source-zone capture, 2) DNAPL occurrence downgradient of the re-injection wells, and 3) back diffusion from one or more thin clay beds in the aquifer. After careful consideration, the first two hypotheses were eliminated, leaving back diffusion as the only plausible hypothesis, supported by detailed measurements of VOC concentrations within and near the clay beds and also by numerical model simulations that closely represent the field site hydrogeologic conditions. The model was also used to simulate a more generalized, hypothetical situation where more thin clayey beds occur in a sand aquifer with an underlying aquitard. While there is no doubt that DNAPL source mass reduction can eventually improve downgradient groundwater quality, the magnitude and time scale over which the improvement occurs is the major uncertainty given current characterization approaches. This study shows that even one thin clay bed, less than 0.2 m thick, can cause plume persistence due to back diffusion for several years or even decades after the flux from the source is completely isolated. Thin clay beds, which have a large storage capacity for dissolved and sorbed contaminant mass, are common in many types of sandy aquifers. However, without careful inspection of continuous cores and sampling, such thin clay beds, and their potential for causing long-term back-diffusion effects, can easily go unnoticed during site characterization.

Use of environmental tracers to study the chemical evolution of shallow ground water in a karst area of northern Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katz, B.G.; Plummer, L.N.; Busenberg, E.

1993-03-01

The pathways of shallow ground-water flow in poorly confined aquifer systems of northern FL are influenced by inflow to and outflow from numerous sinkhole lakes that are characteristic of the Sand Hills karst region. Ground-water samples were collected immediately upgradient and downgradient from Lake Barco at depths of 1.6--29 m below the water table from observation wells completed in the surficial aquifer system, the intermediate confining unit (icu), and the Upper Floridan aquifer. Samples were also collected of rainfall, lake water, and ground water at a depth of 4.1 m beneath the lake bottom. The environmental tracers tritium and chlorofluorocarbonsmore » were used to estimate mean residence times of water and rates of chemical mass transfer along flow paths. Water samples collected from wells upgradient of the lake were oxic and had CFC-model recharge dates between 1971 and 1986. The content of delta H-2 and delta O-18 of water from the two aquifer systems and the icu was nearly identical to the isotopic composition of rainfall. Changes in the chemical composition of the ground water with depth were simulated by reacting rainfall with minerals and dissolved gases that exist in the hydrogeologic units. Ground-water samples collected from sites beneath and downgradient of the lake were anoxic, with measured concentrations of hydrogen sulfide and methane ranging from 0.02--0.58 mg/l and 0.30--6.1 mg/l, respectively. CFC-model recharge dates ranged from 1956 to 1983. The data indicated that ground water downgradient of the lake is being recharged by leakage of lake water. The chemical composition of ground water is influenced by the movement of lake water through reducing, organic-rich sediments accumulated at the bottom. Along the downgradient flow paths, the water chemistry evolves from the composition of lake water and is modified by subsequent reactions including reduction of sulfate and ferric iron, methanogenesis, and dissolution and precipitation of minerals.« less

Geology, hydrology, and water quality of the glacial drift aquifer in the vicinity of the Nelson landfill near Yorkville, Illinois

USGS Publications Warehouse

Kay, Robert T.

2006-01-01

The geologic and hydrologic characteristics of the sand-and-gravel deposits that compose the glacial drift aquifer in the vicinity of the Nelson Landfill site in Yor-kville, Illinois indicate that the aquifer could be devel-oped as a source of public water supply. The geology of these deposits within the Newark Bedrock Valley is com-plex, however, and a detailed investigation of their water bearing and transmitting properties will be required to successfully locate high-capacity wells. Volatile organic compounds, pesticides, and cyanide were not detected in ground water during this investiga-tion. Metals and nitrogen compounds were not detected at concentrations above their Maximum Contaminant Level. Iron, manganese, and aluminum were detected at concentrations above their Secondary Maximum Con-taminant Level and various constituents were detected at concentrations above background levels downgradi-ent of the landfill. Nitrate and ammonia, presumably derived from agricultural practices, also were detected in samples from locations hydraulically upgradient of the landfill. Oxidation-reduction conditions in the aquifer become more reducing with depth. This change is reflected by a change in the type of nitrogen compound detected and the concentration of dissolved oxygen and iron in the glacial drift aquifer. Concentrations of some of the major ions and metals may be affected by disso-lution of carbonate minerals in the aquifer and perhaps road salts.

Delineation and hydrologic effects of a gasoline leak at Stovepipe Wells Hotel, Death Valley National Monument, California

USGS Publications Warehouse

Buono, A.; Packard, Elaine M.

1982-01-01

Ground water is the only local source of water available to the Stovepipe Wells Hotel facilities of the Death Valley National Monument, California. A leak in a service station storage tank caused the formation of a gasoline layer overlying the water table, creating the potential for contamination of the water supply. The maximum horizontal extent of the gasoline layer was mathematically estimated to be 1,300 feet downgradient from the leaky gasoline tank. Exploratory drilling detected the gasoline layer between 900 and 1,400 feet downgradient and between 50 and 150 feet upgradient from the source. Traces of the soluble components of gasoline were also found in the aquifer 150 feet upgradient, and 250 feet distant from the source perpendicular to the direction of ground-water movement. The gasoline spill is not likely to have an effect on the supply wells located 0.4 mile south of the leak source, which is nearly perpendicular to the direction of ground-water movement and the primary direction of gasoline movement in the area. No effect on phreatophytes 2 miles downgradient from the layer is likely, but the potential effects of gasoline vapors within the unsaturated zone on local xerophytes are not known. (USGS)

Entrainment of viruses from septic tank leach fields through a shallow, sandy soil aquifer.

PubMed

Vaughn, J M; Landry, E F; Thomas, M Z

1983-05-01

A study was conducted which focused on movement of naturally occurring human enteroviruses from a subsurface wastewater disposal system through a shallow aquifer. The potential for significant entrainment of virus particles was evidenced by their recovery at down-gradient distances of 67.05 m and from aquifer depths of 18 m. A significant negative correlation was observed between virus occurrence and the distance from the "septage" (leaching pool) source. Virus occurrence could not be statistically correlated with either total or fecal coliforms, indicating the limitations of current microbial water quality indicators for predicting the virological quality of groundwater.

Use of colloid filtration theory in modeling movement of bacteria through a contaminated sandy aquifer

USGS Publications Warehouse

Harvey, R.W.; Garabedian, S.P.

1991-01-01

??? A filtration model commonly used to describe removal of colloids during packed-bed filtration in water treatment applications was modified for describing downgradient transport of bacteria in sandy, aquifer sediments. The modified model was applied to the results of a small-scale (7 m), natural-gradient tracer test and to observations of an indigenous bacterial population moving downgradient within a plume of organically contaminated groundwater in Cape Cod, MA. The model reasonably accounted for concentration histories of labeled bacteria appearing at samplers downgradient from the injection well in the tracer experiment and for the observed 0.25-??m increase in average cell length for an unlabeled, indigenous bacterial population, 0.6 km downgradient from the source of the plume. Several uncertainties were apparent in applying filtration theory to problems involving transport of bacteria in groundwater. However, adsorption (attachment) appeared to be a major control of the extent of bacterial movement downgradient, which could be described, in part, by filtration theory. Estimates of the collision efficiency factor, which represents the physicochemical factors that determine adsorption of the bacteria onto the grain surfaces, ranged from 5.4 ?? 10-3 to 9.7 ?? 10-3.

Data Validation Package October 2016 Groundwater and Surface Water Sampling at the Monticello, Utah, Disposal and Processing Sites January 2017

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Jason; Smith, Fred

Sampling Period: October 10–12, 2016. This semiannual event includes sampling groundwater and surface water at the Monticello Disposal and Processing Sites. Sampling and analyses were conducted as specified in the Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated) and Program Directive MNT-2016-01. Samples were collected from 54 of 64 planned locations (16 of 17 former mill site wells, 15 of 18 downgradient wells, 7 of 9 downgradient permeable reactive barrier wells, 3 of 3 bedrock wells, 4 of 7 seeps and wetlands, and 9 of 10 surface water locations).

Water chemistry near the closed Norman Landfill, Cleveland County, Oklahoma 1995

USGS Publications Warehouse

Schlottmann, Jamie L.

2001-01-01

The Norman Landfill was selected for study as part of the U.S. Geological Survey Toxic Substances Hydrology Program in 1994. The landfill is located south of the City of Norman on alluvial deposits of the Canadian River. Type of waste deposited in the landfill from 1922 to 1973 was largely unrestricted and may include substances now recognized as hazardous. Dissolved and suspended substances leached from wastes in the closed and capped landfill are now in ground water extending toward the Canadian River as a plume of leachate. Water samples were collected from two stock wells, one domestic well, temporary drive-point wells, the Canadian River, and a small intermittent stream hydraulically downgradient of the capped landfill known as the slough. Most constituent concentrations were greater in ground water downgradient from the capped landfill than in background ground water and were greater in the slough than in the Canadian River. Concentrations of most constituents in the Canadian River, other than sulfate, manganese, and iron, were similar to concentrations in background ground water. Some constituents measured in ground-water for this investigation are potential indicators of leachate contamination. Potential indicators that could be used to differentiate leachate contaminated water from uncontaminated ground water of the alluvial aquifer include specific conductance, chloride, alkalinity, dissolved organic carbon, boron, and dD. Specific conductance and chloride were greater in water from wells downgradient of the landfill than water from background wells. Dissolved organic carbon and boron also were greater in the leachate contaminated ground water than in background ground water.

Review of factors affecting recovery of freshwater stored in saline aquifers

USGS Publications Warehouse

Merritt, Michael L.

1989-01-01

A simulation analysis reported previously, and summarized herein, identified the effects of various geohydrologic and operational factors on recoverability of the injected water. Buoyancy stratification, downgradient advection, and hydrodynamic dispersion are the principal natural processes that reduce the amount of injected water that can be recovered. Buoyancy stratification is shown to depend on injection-zone permeability and the density contrast between injected and saline native water. Downgradient advection occurs as a result of natural or induced hydraulic gradients in the aquifer. Hydrodynamic dispersion reduces recovery efficiency by mixing some of the injected water with native saline aquifer water. In computer simulations, the relation of recovery efficiency to volume injected and its improvement during successive injection-recovery cycles was shown to depend on changes in the degree of hydrodynamic dispersion that occurs. Additional aspects of the subject are discussed.

Ground-water quality along the Mojave River near Barstow, California, 1974-79

USGS Publications Warehouse

Eccles, Lawrence A.

1981-01-01

The quality of ground water in the alluvium along the usually dry Mojave River near Barstow, Calif., has been monitored since 1974. Degradation has occurred as a result of wastewater discharge and irrigation return. Characteristics of the degraded ground water include concentrations of dissolved solids exceeding 1,000 milligrams per liter, odor threshold numbers exceeding 5, dissolved organic carbon exceeding 2.0 milligrams per liter, chloride exceeding 250 milligrams per liter, phenols exceeding 1 microgram per liter, and methylene blue active substances exceeding 0.20 milligram per liter. Large flows in the river during the winters of 1977-78 and 1978-79 recharged the aquifer with water from storm runoff. The ground-water-quality monitoring data showed that few changes in the concentration and distribution of chemical constituents occurred between 1974 and 1977, but between 1977 and 1979 there were overall decreases in most constituents and in odor. The monitoring data also showed that between 1977 and 1979 the degraded ground water spread and moved downgradient, whereas prior to 1977 it had been generally confined to an area between Barstow and the U.S. Marine Corps Supply Center. (USGS)

Hydrogeology and water quality near a solid- and hazardous-waste landfill, Northwood, Ohio

USGS Publications Warehouse

De Roche, J.T.; Breen, K.J.

1989-01-01

Hydrogeology and water quality of ground water and selected streams were evaluated near a landfill in northwestern Ohio. The landfill is used for codisposal of solid and hazardous waste. Water-level and geologic data were collected from 36 wells and 3 surface-water sites during the period November 1983 to November 1985. Water-quality samples were collected from 18 wells and 3 surface-water sites this during this same period. The primary aquifers in the area are the Greenfield Dolomite and underlying Lockport Dolomite of Silurian age. These bedrock carbonates are overlain by two clay tills of Wisconsin age. The tills are capped by a glacial lake clay. The tills generally are saturated, but do not yield sufficient water to be considered an aquifer. Two wells in the study area yield water, in part, from discontinuous deposits of outwash sand and gravel at the lower till-bedrock interface. Regional ground-water flow is from southwest to northeast; local flow is influenced by a ground-water mound centered under the northernmost cells of the landfill. Water levels in wells penetrating refuse within the landfill and the presence of leachate seeps indicate that the refuse is saturated. Head relations among the landfill, till, and dolomite aquifer indicate a vertical component of flow downward from the landfill to the dolomite aquifer. Water levels near the landfill fluctuate as much as 14 feet per year, in contrast to fluctuations of less than 3 feet per year in wells upgradient landfill. Ground waters from wells completed in the dolomite aquifer and glacial till were found to have major-iron concentrations controlled, in large part, by reaction with calcite, dolomite, and other minerals in the aquifer. Only minor departures from equilibrium mineral saturation were noted for ground water, except in wells affected by cement/grout contamination. Molal ratios of calcuim:magnesium in ground water suggest a similar chemical evolution of waters throughout the dolomite aquifer in the study area. Stable-isotope ratios of oxygen and hydrogen indicate the source of water in the till unit and dolomite aquifer is atmospheric precipitation. Elevated levels of total dissolved solids, boron, ammonia, and iron in the leachate and in wells downgradient of the landfill may indicate mixing of ground water with leachate. Oxygen and hydrogen stable-isotope ratios were used to differentiate waters from the glacial till and dolomite aquifer. Isotope ratios also show a shift off the local mixing line for leachate and for a well just downgradient from the landfill. The shift to heavier values of o D in the well water may be indicative of leachate mixing with ground water. The effect of this mixing denoted by hydrologic, isotopic, and chemical-quality data is limited mostly to elevated levels of the common ions. Analysis did not indicate significant levels of toxic metals or organic contaminants except phenol, which was present at concentrations of from 1 to 5 micrograms per liter in six wells. Analysis of water-quality data from nearby streams suggest that surface leaching from the landfill does not significantly affect stream-water quality, but may contribute to higher level of trace metals in the streambed sediments.

Effects of septic-tank effluent on ground-water quality in northern Williamson County and southern Davidson County, Tennessee

USGS Publications Warehouse

Hanchar, D.W.

1991-01-01

An investigation of the potential contamination of ground water from septic tank systems blasted in bedrock in Williamson and Davidson Counties, Tennessee, was conducted during 1988-89. Water samples were collected from domestic and observation wells, springs, and surface-water sites in a residential subdivision in the northern part of Williamson County near Nashville. The subdivision has a high density of septic-tank field lines installed into blasted bedrock Water samples also were collected from a well located in an area of Davidson County where field lines were installed in 5 feet of soil. Samples were analyzed for major inorganic constituents, nutrients, total organic carbon, optical brighteners, and bacteria. Although results of analyses of water samples from wells indicate no effect of septic-tank effluent on ground-water quality at these sites, water from two springs located downgradient from the subdivision had slightly larger concentrations of nitrite plus nitrate (2.2 and 2.7 milligrams per liter N), and much larger concentrations of fecal coliform and fecal streptococci bacteria (2,000 to 3,200 and 700 to 900 colonies per 100 milliliters of sample, respectively), than other wells and springs sampled during 1988. Water from one of these springs contained optical brighteners, which indicates that septic-tank effluent is affecting ground-water quality.

Effects of effluent spray irrigation on ground water at a test site near Tarpon Springs, Florida

USGS Publications Warehouse

Brown, D.P.

1982-01-01

Secondary-treated effluent was applied to a 7.2-acre test site near Tarpon Springs, Fla., for about 1 year at an average rate of 0.06 million gallons per day and 3 years at 0.11 million gallons per day. Chemical fertilizer was applied periodically to the test site and adjacent areas. Periodic mounding of the water table occurred due to effluent irrigation, inducing radial flow from the test site. Physical, geochemical, biochemical processes effectively reduced total nitrogen concentration 90% and total phosphorous concentration more than 95% in the ground water of the surficial aquifer about 300 feet downgradient from the test site from that of the applied effluent. Downgradient, total nitrogen averaged 2.4 milligrams per liter and total phosphorus averaged 0.17 milligrams per liter. Substantial increases in total phosphorus were observed when the pH of the ground water increased. Total coliform bacteria in the ground water of the surficial aquifer were generally less than 100 colonies per 100 milliliters. Fecal coliform bacteria were generally less than 25 colonies per 100 milliliters at the test site and were not detected downgradient or near the test site. Fecal streptococcal bacteria were generally less than 100 colonies per 100 milliliters at the test site, but were detected on three occasions near the test site. (USGS)

Water Quality and Geochemical Modeling of Water at an Abandoned Coal Mine Reclaimed With Coal Combustion By-Products

USGS Publications Warehouse

Haefner, Ralph J.

2002-01-01

An abandoned coal mine in eastern Ohio was reclaimed with 125 tons per acre of pressurized fluidized bed combustion (PFBC) by-product. Water quality at the site (known as the Fleming site) was monitored for 7 years after reclamation; samples included water from soil-suction lysimeters (interstitial water), wells, and spring sites established downgradient of the application area. This report presents a summary of data collected at the Fleming site during the period September 1994 through June 2001. Additionally, results of geochemical modeling are included in this report to evaluate the potential fate of elements derived from the PFBC by-product. Chemical analyses of samples of interstitial waters within the PFBC by-product application area indicated elevated levels of pH and specific conductance and elevated concentrations of boron, calcium, chloride, fluoride, magnesium, potassium, strontium, and sulfate compared to water samples collected in a control area where traditional reclamation methods were used. Magnesium-to-calcium (Mg:Ca) mole ratios and sulfur-isotope ratios were used to trace the PFBC by-product leachate and showed that little, if any, leachate reached ground water. Concentrations of most constituents in interstitial waters in the application-area decreased during the seven sampling rounds and approached background concentrations observed in the control area; however, median pH in the application area remained above 6, indicating that some acid-neutralizing capacity was still present. Although notable changes in water quality were observed in interstitial waters during the study period, quality of ground water and spring water remained poor. Water from the Fleming site was not potable, given exceedances of primary and secondary Maximum Contaminant Levels (MCLs) for inorganic constituents in drinking water set by the U.S. Environmental Protection Agency. Only fluoride and sulfate, which were found in higher concentrations in application-area interstitial waters than in control-area interstitial waters, could be related to the PFBC by-product. Concentrations of arsenic, lead, and selenium typically were at or below the detection limits (generally 1 or 2 micrograms per liter). Elements detected at elevated concentrations in PFBC by-product application-area interstitial waters were not evident in downgradient ground water or spring water. Dilution of leachate by ground water was confirmed with a mixing model generated by the computer code NETPATH. Additionally, thermodynamic modeling of the chemical composition of water samples by use of the computer code PHREEQC indicated favorable conditions for precipitation of secondary minerals in the unsaturated zone and in aquifer materials. Because of low application rates of PFBC by-product and precipitation and sorption of elements in the unsaturated zone, it is improbable that concentrations of any toxic elements of concern (arsenic, lead, or selenium) will exceed drinking-water standards at this site or other sites where similar volumes of PFBC by-products are used.

Ground-water quality in the vicinity of landfill sites, southern Franklin County, Ohio

USGS Publications Warehouse

De Roche, J.T.; Razem, A.C.

1981-01-01

The hydrogeology and ground-water quality in the vicinity of five landfills in southern Franklin County, Ohio, were investigated by use of data obtained from 46 existing wells, 1 seep, 1 surface-water site, and 1 leachate-collection site. Interpretation was based on data from the wells, a potentiometric-surface map, and chemical analyses. Four of the five landfills are in abandoned sand and gravel pits. Pumping of water from a quarry near the landfills has modified the local ground-water flow pattern, increased the hydraulic gradient, and lowered the water table. Ground water unaffected by the landfills is a hard, calcium bicarbonate type with concentrations of dissolved iron and dissolved sulfate as great as 3.0 milligrams per liter and 200 milligrams per liter, respectively. Water sampled from wells downgradient from two landfills shows an increase in sodium, chloride, and other constituents. The change in water quality cannot be traced directly to the landfills, however, because of well location and the presence of other potential sources of contamination. Chemical analysis of leachate from a collection unit at one landfill shows significant amounts of zinc, chromium, copper, and nickel, in addition to high total organic carbon, biochemical oxygen demand, and organic nitrogen. Concentrations of chloride, iron, lead, manganese and phenolic compounds exceed Ohio Environmental Protection Agency Water Quality Standards for drinking water. Water from unaffected wells within the study area have relatively small amounts of these constituents. (USGS)

Geohydrology and ground-water quality at the Pueblo Depot activity landfill near Pueblo, Colorado

USGS Publications Warehouse

Watts, Kenneth R.; Ortiz, Roderick F.

1990-01-01

Groundwater samples were collected from the shallow unconfined aquifer at the Pueblo Depot Activity (Colorado) landfill and downstream from the landfill. The Pueblo Depot Activity is a U.S. Department of the Army facility in southeastern Colorado about 15 miles east of Pueblo, Colorado. The land-fill is underlain by upland alluvial terrace deposits that overlie a thick and almost impermeable shale. Saturated thickness of the aquifer generally is from 5 to 10 feet. Groundwater flow at the landfill is to the south-southeast toward the Arkansas River valley. Though not hydraulically connected to the upland terrace deposits, the alluvium underlying the Arkansas River valley may be recharged by groundwater that is discharged from seeps at the contact of the upland terrace deposits and the Pierre Shale. The water is classified as a mixed-cation mixed-anion type water that has concentrations of dissolved solids of 710 to 1,810 mg/L. Dissolved-solids concentrations increase downgradient. Chemical analysis, done to determine possible contamination of the groundwater, indicated that concentrations of trichloroethylene ranged from 5.2 to 2,900 microg/L and of trans-1,2-dichloroethylene ranged from 5 to 720 microg/L. The areal distribution of these volatile organic compounds indicate that there possibly are two sources of contamination of groundwater at the landfill, one upgradient from the landfill and the other within the landfill. Analysis of water samples from wells and seeps offsite and downgradient from the landfill did not indicate either contaminant in groundwater from the alluvial aquifer underlying the Arkansas River valley. (USGS)

Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 2. Chemical Patterns, Mass Transfer Modeling, and Rates of Mass Transfer Reactions

NASA Astrophysics Data System (ADS)

Katz, Brian G.; Plummer, L. Niel; Busenberg, Eurybiades; Revesz, Kinga M.; Jones, Blair F.; Lee, Terrie M.

1995-06-01

Chemical patterns along evolutionary groundwater flow paths in silicate and carbonate aquifers were interpreted using solute tracers, carbon and sulfur isotopes, and mass balance reaction modeling for a complex hydrologic system involving groundwater inflow to and outflow from a sinkhole lake in northern Florida. Rates of dominant reactions along defined flow paths were estimated from modeled mass transfer and ages obtained from CFC-modeled recharge dates. Groundwater upgradient from Lake Barco remains oxic as it moves downward, reacting with silicate minerals in a system open to carbon dioxide (CO2), producing only small increases in dissolved species. Beneath and downgradient of Lake Barco the oxic groundwater mixes with lake water leakage in a highly reducing, silicate-carbonate mineral environment. A mixing model, developed for anoxic groundwater downgradient from the lake, accounted for the observed chemical and isotopic composition by combining different proportions of lake water leakage and infiltrating meteoric water. The evolution of major ion chemistry and the 13C isotopic composition of dissolved carbon species in groundwater downgradient from the lake can be explained by the aerobic oxidation of organic matter in the lake, anaerobic microbial oxidation of organic carbon, and incongruent dissolution of smectite minerals to kaolinite. The dominant process for the generation of methane was by the CO2 reduction pathway based on the isotopic composition of hydrogen (δ2H(CH4) = -186 to -234‰) and carbon (δ13C(CH4) = -65.7 to -72.3‰). Rates of microbial metabolism of organic matter, estimated from the mass transfer reaction models, ranged from 0.0047 to 0.039 mmol L-1 yr-1 for groundwater downgradient from the lake.

Simulation of ground-water flow in the St. Peter aquifer in an area contaminated by coal-tar derivatives, St. Louis Park, Minnesota. Water Resources Investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorenz, D.L.; Stark, J.R.

1990-01-01

A model constructed to simulate ground-water flow in part of the Prairie du Chien-Jordan and St. Peter aquifers, St. Louis Park, Minnesota, was used to test hypotheses about the movement of ground water contaminated with coal-tar derivatives and to simulate alternatives for reducing the downgradient movement of contamination in the St. Peter aquifer. The model, constructed for a previous study, was applied to simulate the effects of current ground-water withdrawals on the potentiometric surface of the St. Peter aquifer. Model simulations predict that the multiaquifer wells have the potential to limit downgradient migration of contaminants in the St. Peter aquifermore » caused by cones of depression created around the multiaquifer wells. Differences in vertical leakage to the St. Peter aquifer may exist in areas of bedrock valleys. Model simulations indicate that these differences are not likely to affect significantly the general patterns of ground-water flow.« less

Application of environmental tracers to delineate recharge patterns and nitrate contamination in shallow groundwater around a river

NASA Astrophysics Data System (ADS)

Kaown, Dugin; Koh, Eunhee; Park, Byeong-Hak; Lee, Kang-Kun

2016-04-01

Hydrogeochemical data, stable isotopes, chlorofluorocarbon (CFCs) and 3H-3He in groundwater were applied to characterize residence time, recharge patterns and nitrate contamination of groundwater in a small agricultural area, Yangpyung, Korea. The study area is located around a river and the measured groundwater table ranges from 1.5 to 2.65 m during the year. Most residents in the study area practice agriculture and potato, strawberry, and cabbage are the typical vegetables grown. Vegetable fields are mostly located in the upgradient area of the study area while forest and residence areas are located in the downgradient area. A lot of chemical and organic fertilizers are applied in the upgradient area. The concentration of NO3-N in groundwater showed 9.8-83.7 mg/L in the upgradient area and 0.1-22.6 mg/L in the downgradient area in 2014. It is necessary to monitor groundwater recharge patterns and transport processes of nitrate to protect surface water around the study area. The values of δ18O and δD showed that groundwater is recharged mainly from summer precipitation. The apparent groundwater ages using 3H-3He and CFCs ranged from 13 to 27 years in the upgradient area and from 25 to 35 years in the downgradient area. The NO3-N in more recently recharged groundwater showed higher concentrations while the NO3-N in older groundwater showed low concentrations. Some shallow wells in the downgradient area showed similar apparent groundwater age with that of the river water indicating groundwater-surface water interactions. A conceptual model of groundwater-surface water interactions using stable isotopes, apparent 3H-3He and CFCs age in groundwater will be useful to understand the hydrological processes and nitrate contamination of the study area.

Rare Earth Element Concentrations and Fractionation Patterns Along Groundwater Flow Paths in Two Different Aquifer Types (i.e., Sand vs. Carbonate)

NASA Astrophysics Data System (ADS)

Johannesson, K. H.; Tang, J.

2003-12-01

Groundwater samples were collected in two different types of aquifer (i.e., Carrizo Sand Aquifer, Texas and Upper Floridan carbonate Aquifer, west-central Florida) to study the concentrations, fractionation, and speciation of rare earth elements (REE) along groundwater flow paths in each aquifer. Major solutes and dissolved organic carbon (DOC) were also measured in these groundwaters. The Carrizo Sand aquifer was sampled in October 2002 and June 2003, whereas, to date, we have only sampled the Floridan once (i.e., June 2003). The data reveal no significant seasonal differences in major solute and REE concentrations for the Carrizo. In Carrizo sand aquifer, groundwaters from relatively shallow wells (i.e., less than 167 m) in the recharge zone are chiefly Ca-Na-HCO3-Cl type waters. With flow down-gradient the groundwaters shift composition to the Na-HCO3 waters. pH and alkalinity initially decrease with flow away from the recharge zone before increasing again down-gradient. DOC is generally low (0.65 mg/L) along the flow path. REE concentrations are highest in groundwaters from the recharge zone (Nd 40.5 pmol/kg), and decrease substantially with flow down-gradient reaching relatively low and stable values (Nd 4.1-8.6 pmol/kg) roughly 10 km from the recharge zone. Generally, Carrizo groundwaters exhibit HREE-enriched shale-normalized patterns. The HREE enrichments are especially strong for waters from the recharge zone [(Yb/Nd)SN =1.7-5.6], whereas down-gradient (deep) groundwaters have flatter patterns [(Yb/Nd)SN =0.7-2.5]. All groundwaters have slightly positive Eu anomalies (Eu/Eu* 0.09-0.14) and negative Ce anomalies (Ce/Ce* -0.85 - -0.07). In the Upper Floridan Aquifer, Ca, Mg, SO4, and Cl concentrations generally increase along groundwater flow path, whereas pH and alkalinity generally decrease. DOC is higher (0.64 - 2.29 mg/L) than in the Carrizo and initially increases along the flow path and then decreases down-gradient. LREE (Nd) concentrations generally increase along groundwater flow path, however, MREE (Gd) exhibit little change and HREE (Yb) concentrations tend to decreases along the flow path. Floridan groundwaters have HREE enriched shale-normalized patterns, although (Yb/Nd)SN values decrease along groundwater flow path. Thus, REE patterns of Floridan groundwaters tend to flatten with flow down-gradient. All groundwaters show positive Eu anomalies (0.06 - 0.17) and negative Ce anomalies (-0.12 - -0.63).

Does Disposing of Construction and Demolition Debris in Unlined Landfills Impact Groundwater Quality? Evidence from 91 Landfill Sites in Florida.

PubMed

Powell, Jon T; Jain, Pradeep; Smith, Justin; Townsend, Timothy G; Tolaymat, Thabet M

2015-08-04

More than 1,500 construction and demolition debris (CDD) landfills operate in the United States (U.S.), and U.S. federal regulations do not require containment features such as low-permeability liners and leachate collection systems for these facilities. Here we evaluate groundwater quality from samples collected in groundwater monitoring networks at 91 unlined, permitted CDD landfills in Florida, U.S. A total of 460,504 groundwater sample results were analyzed, with a median of 10 years of quarterly or semiannual monitoring data per site including more than 400 different chemical constituents. Downgradient concentrations of total dissolved solids, sulfate, chloride, iron, ammonia-nitrogen, and aluminum were greater than upgradient concentrations (p < 0.05). At downgradient wells where sulfate concentrations were greater than 150 mg/L (approximately 10% of the maximum dissolved sulfate concentration in water, which suggests the presence of leachate from the landfill), iron and arsenic were detected in 91% and 43% of samples, with median concentrations of 1,900 μg/L and 11 μg/L, respectively. These results show that although health-based standards can be exceeded at unlined CDD landfills, the magnitude of detected chemical concentrations is generally small and reflective of leached minerals from components (wood, concrete, and gypsum drywall) that comprise the bulk of discarded CDD by mass.

Hydrologic data for a study of pre-Illinoian glacial till in Linn County, Iowa, water year 1990

USGS Publications Warehouse

Bowman, Phillip R.

1991-01-01

Ten unvented, vibrating-wire, pressure transducers with internal thermistors were buried in two boreholes at upgradient and downgradient locations to record hydraulic pressure arid water temperature at selected depths.

40 CFR Appendix F to Part 112 - Facility-Specific Response Plan

Code of Federal Regulations, 2014 CFR

2014-07-01

... into a wellhead protection area as defined by the Safe Drinking Water Act of 1986 (SDWA). 1 The...) Water intakes (drinking, cooling, or other); (2) Schools; (3) Medical facilities; (4) Residential areas... discharge; (2) Proximity to downgradient wells, waterways, and drinking water intakes; (3) Proximity to fish...

Old groundwater in parts of the upper Patapsco aquifer, Atlantic Coastal Plain, Maryland, USA: Evidence from radiocarbon, chlorine-36 and helium-4

USGS Publications Warehouse

Plummer, Niel; Eggleston, John R.; Raffensperger, Jeff P.; Hunt, Andrew G.; Casile, Gerolamo C.; Andreasen, D.C.

2012-01-01

Apparent groundwater ages along two flow paths in the upper Patapsco aquifer of the Maryland Atlantic Coastal Plain, USA, were estimated using 14C, 36Cl and 4He data. Most of the ages range from modern to about 500 ka, with one sample at 117 km downgradient from the recharge area dated by radiogenic 4He accumulation at more than one Ma. Last glacial maximum (LGM) water was located about 20 km downgradient on the northern flow path, where the radiocarbon age was 21.5 ka, paleorecharge temperatures were 0.5–1.5  °C (a maximum cooling of about 12 °C relative to the modern mean annual temperature of 13 °C), and Cl–, Cl/Br, and stable isotopes of water were minimum. Low recharge temperatures (typically 5–7 °C) indicate that recharge occurred predominantly during glacial periods when coastal heads were lowest due to low sea-level stand. Flow velocities averaged about 1.0 m a–1 in upgradient parts of the upper Patapsco aquifer and decreased from 0.13 to 0.04 m a–1 at 40 and 80 km further downgradient, respectively. This study demonstrates that most water in the upper Patapsco aquifer is non-renewable on human timescales under natural gradients, thus highlighting the importance of effective water-supply management to prolong the resource.

Screening tool to evaluate the vulnerability of down-gradient receptors to groundwater contaminants from uncapped landfills

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Ronald J.; Reilly, Timothy J.; Lopez, Anthony

2015-09-15

Highlights: • A spreadsheet-based risk screening tool for groundwater affected by landfills is presented. • Domenico solute transport equations are used to estimate downgradient contaminant concentrations. • Landfills are categorized as presenting high, moderate or low risks. • Analysis of parameter sensitivity and examples of the method’s application are given. • The method has value to regulators and those considering redeveloping closed landfills. - Abstract: A screening tool for quantifying levels of concern for contaminants detected in monitoring wells on or near landfills to down-gradient receptors (streams, wetlands and residential lots) was developed and evaluated. The tool uses Quick Domenicomore » Multi-scenario (QDM), a spreadsheet implementation of Domenico-based solute transport, to estimate concentrations of contaminants reaching receptors under steady-state conditions from a constant-strength source. Unlike most other available Domenico-based model applications, QDM calculates the time for down-gradient contaminant concentrations to approach steady state and appropriate dispersivity values, and allows for up to fifty simulations on a single spreadsheet. Sensitivity of QDM solutions to critical model parameters was quantified. The screening tool uses QDM results to categorize landfills as having high, moderate and low levels of concern, based on contaminant concentrations reaching receptors relative to regulatory concentrations. The application of this tool was demonstrated by assessing levels of concern (as defined by the New Jersey Pinelands Commission) for thirty closed, uncapped landfills in the New Jersey Pinelands National Reserve, using historic water-quality data from monitoring wells on and near landfills and hydraulic parameters from regional flow models. Twelve of these landfills are categorized as having high levels of concern, indicating a need for further assessment. This tool is not a replacement for conventional numerically-based transport model or other available Domenico-based applications, but is suitable for quickly assessing the level of concern posed by a landfill or other contaminant point source before expensive and lengthy monitoring or remediation measures are taken. In addition to quantifying the level of concern using historic groundwater-monitoring data, the tool allows for archiving model scenarios and adding refinements as new data become available.« less

Screening tool to evaluate the vulnerability of down-gradient receptors to groundwater contaminants from uncapped landfills

USGS Publications Warehouse

Baker, Ronald J.; Reilly, Timothy J.; Lopez, Anthony R.; Romanok, Kristin M.; Wengrowski, Edward W

2015-01-01

A screening tool for quantifying levels of concern for contaminants detected in monitoring wells on or near landfills to down-gradient receptors (streams, wetlands and residential lots) was developed and evaluated. The tool uses Quick Domenico Multi-scenario (QDM), a spreadsheet implementation of Domenico-based solute transport, to estimate concentrations of contaminants reaching receptors under steady-state conditions from a constant-strength source. Unlike most other available Domenico-based model applications, QDM calculates the time for down-gradient contaminant concentrations to approach steady state and appropriate dispersivity values, and allows for up to fifty simulations on a single spreadsheet. Sensitivity of QDM solutions to critical model parameters was quantified. The screening tool uses QDM results to categorize landfills as having high, moderate and low levels of concern, based on contaminant concentrations reaching receptors relative to regulatory concentrations. The application of this tool was demonstrated by assessing levels of concern (as defined by the New Jersey Pinelands Commission) for thirty closed, uncapped landfills in the New Jersey Pinelands National Reserve, using historic water-quality data from monitoring wells on and near landfills and hydraulic parameters from regional flow models. Twelve of these landfills are categorized as having high levels of concern, indicating a need for further assessment. This tool is not a replacement for conventional numerically-based transport model or other available Domenico-based applications, but is suitable for quickly assessing the level of concern posed by a landfill or other contaminant point source before expensive and lengthy monitoring or remediation measures are taken. In addition to quantifying the level of concern using historic groundwater-monitoring data, the tool allows for archiving model scenarios and adding refinements as new data become available.

Use of chemical and isotopic tracers to characterize the interactions between ground water and surface water in mantled karst

USGS Publications Warehouse

Katz, B.G.; Coplen, T.B.; Bullen, T.D.; Hal, Davis J.

1997-01-01

In the mantled karst terrane of northern Florida, the water quality of the Upper Floridan aquifer is influenced by the degree of connectivity between the aquifer and the surface. Chemical and isotopic analyses [18O/16O (??18O), 2H/1H (??D), 13C/12C (??13C), tritium(3H), and strontium-87/strontium-86(87Sr/86Sr)]along with geochemical mass-balance modeling were used to identify the dominant hydrochemical processes that control the composition of ground water as it evolves downgradient in two systems. In one system, surface water enters the Upper Floridan aquifer through a sinkhole located in the Northern Highlands physiographic unit. In the other system, surface water enters the aquifer through a sinkhole lake (Lake Bradford) in the Woodville Karst Plain. Differences in the composition of water isotopes (??18O and ??D) in rainfall, ground water, and surface water were used to develop mixing models of surface water (leakage of water to the Upper Floridan aquifer from a sinkhole lake and a sinkhole) and ground water. Using mass-balance calculations, based on differences in ??18O and ??D, the proportion of lake water that mixed with meteoric water ranged from 7 to 86% in water from wells located in close proximity to Lake Bradford. In deeper parts of the Upper Floridan aquifer, water enriched in 18O and D from five of 12 sampled municipal wells indicated that recharge from a sinkhole (1 to 24%) and surface water with an evaporated isotopic signature (2 to 32%) was mixing with ground water. The solute isotopes, ??13C and 87Sr/86Sr, were used to test the sensitivity of binary and ternary mixing models, and to estimate the amount of mass transfer of carbon and other dissolved species in geochemical reactions. In ground water downgradient from Lake Bradford, the dominant processes controlling carbon cycling in ground water were dissolution of carbonate minerals, aerobic degradation of organic matter, and hydrolysis of silicate minerals. In the deeper parts of the Upper Floridan aquifer, the major processes controlling the concentrations of major dissolved species included dissolution of calcite and dolomite, and degradation of organic matter under oxic conditions. The Upper Floridan aquifer is highly susceptible to contamination from activities at the land surface in the Tallahassee area. The presence of post-1950s concentrations of 3H in ground water from depths greater than 100 m below land surface indicates that water throughout much of the Upper Floridan aquifer has been recharged during the last 40 years. Even though mixing is likely between ground water and surface water in many parts of the study area, the Upper Floridan aquifer produces good quality water, which due to dilution effects shows little if any impact from trace elements or nutrients that are present in surface waters.The water quality of the Upper Floridan aquifer is influenced by the degree of connectivity between the aquifer and the surface water. Chemical and isotopic analyses, tritium, and strontium-87/strontium-86 along with geochemical mass-balance modeling were used to identify the dominant hydrochemical processes that control the composition of groundwater. Differences in the composition of water isotopes in rainfall, groundwater and surface water were used to develop mixing models of surface water and groundwater. Even though mixing is likely between groundwater and surface water in many parts of the study area, the Upper Floridan aquifer produces good quality water, showing little impact from trace elements present in surface waters.

2016 Annual Reuse Report for the Idaho National Laboratory Site’s Advanced Test Reactor Complex Cold Waste Ponds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Michael George

This report describes conditions and information, as required by the state of Idaho, Department of Environmental Quality Reuse Permit I-161-02, for the Advanced Test Reactor Complex Cold Waste Ponds located at Idaho National Laboratory from November 1, 2015–October 31, 2016. The effective date of Reuse Permit I-161-02 is November 20, 2014 with an expiration date of November 19, 2019. This report contains the following information: • Facility and system description • Permit required effluent monitoring data and loading rates • Permit required groundwater monitoring data • Status of compliance activities • Issues • Discussion of the facility’s environmental impacts. Duringmore » the 2016 permit year, 180.99 million gallons of wastewater were discharged to the Cold Waste Ponds. This is well below the maximum annual permit limit of 375 million gallons. As shown by the groundwater sampling data, sulfate and total dissolved solids concentrations are highest in well USGS-065, which is the closest downgradient well to the Cold Waste Ponds. Sulfate and total dissolved solids concentrations decrease rapidly as the distance downgradient from the Cold Waste Ponds increases. Although concentrations of sulfate and total dissolved solids are significantly higher in well USGS-065 than in the other monitoring wells, both parameters remained below the Ground Water Quality Rule Secondary Constituent Standards in well USGS-065. The facility was in compliance with the Reuse Permit during the 2016 permit year.« less

Hydrogeology and hydrochemistry of a shallow alluvial aquifer, western Saudi Arabia

NASA Astrophysics Data System (ADS)

Al-Shaibani, Abdulaziz M.

2008-02-01

A hydrogeological and hydrochemical study was conducted on a shallow alluvial aquifer, Wadi Wajj, in western Saudi Arabia to assess the influence of protection measures on groundwater quality. The hydrochemistry was assessed up-gradient and down-gradient from potential contamination sources in the main city in dry and wet seasons prior to and after the installation of major drainage and wastewater facilities. Wadi Wajj is an unconfined aquifer where water is stored and transmitted through fractured and weathered bedrock and the overlying alluvial sediments. Natural recharge to the aquifer is about 5% of rainfall-runoff. Hydrochemistry of the aquifer shows temporal and seasonal changes as influenced by protection measures and rainfall runoff. Both groundwater and runoff showed similar chemical signature, which is mostly of chloride-sulfate-bicarbonate and sodium-calcium type. Groundwater downstream of the city, though of poorer quality than upstream, showed significant improvement after the installation of a concrete runoff tunnel and a wastewater treatment plant. Concentrations of many of the groundwater quality indicators (e.g., TDS, coliform bacteria, and nitrate) exceed US Environmental Protection Agency drinking-water standards. Heavy metal content is, however, within allowable limits by local and international standards. The chemical analyses also suggest the strong influence of stream runoff and sewage water on the groundwater quality.

Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis

NASA Astrophysics Data System (ADS)

VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

2005-08-01

Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. > 9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and δ13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched δ13C values compared to the upgradient mean. In addition, δ13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis.

PubMed

VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

2005-08-01

Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. >9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and delta13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched delta13C values compared to the upgradient mean. In addition, delta13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

Streamflow, water-quality, and biological conditions in the Big Black Creek basin, St. Clair County, Alabama, 1997

USGS Publications Warehouse

Journey, Celeste A.; Clark, Amy E.; Stricklin, Victor E.

1998-01-01

In 1997 synoptic streamflow, water-quality, and biological investi- gations in the Big Black Creek Basin were conducted by the U.S. Geological Survey in cooperation with the City of Moody, St. Clair County, and the Birmingham Water Works Board. Data obtained during these synoptic investigations provide a one-time look at the streamflow and water-quality conditions in the Big Black Creek Basin during a stable, base-flow period when streamflow originated only from ground-water discharge. These data were used to assess the degree of water-quality degradation in the Big Black Creek Basin from land-use activities in the basin, including leakage of leachate from the Acmar Regional Land- fill. Biological data from the benthic invertebrate community investigation provided an assessment of the cumulative effects of stream conditions on organisms in the basin. The synoptic measurement of streamflow at 28 sites was made during a period of baseflow on August 27, 1997. Two stream reaches above the landfill lost water to the ground-water system, but those below the landfill had significantly higher ground-water gains. If significant leakage of leachate from the landfill had occurred during the measurement period, the distribution of ground-water discharge suggests that leachate would travel relatively short distances before resurfacing as ground-water discharge to the stream. Benthic invertebrate communities were sampled at four sites in the Big Black Creek Basin during July 16-17, 1997. Based on Alabama Department of Environmental Management criteria and on comparison with a nearby unimparied reference site, the benthic invertebrate communities at the sites sampled were considered unimpaired or only slightly impaired during the sample period. This would imply that landfill and coal-mining activities did not have a detrimental effect on the benthic invertebrate communities at the time of the study. Synoptic water-column samples were collected at nine sites on Big Black Creek and its tributaries at the same time that the synoptic streamflow measurements were made. Trace-element and organic compound concentrations in the stream water were below established water-quality standards and criteria for the State of Alabama, with the exception of secondary (aesthetic) drinking-water levels for iron and manganese. Oil and grease concentrations detected in bed sediments were below the corrective action limit of 100 milligrams per kilogram. No significant increases in chloride, specific conductance, total dissolved solids, oil and grease, color, or biochemical oxygen demand were observed at sites downgradient from the landfill. Ground-water samples were collected from three drive-point wells in the vicinity of the landfill. These samples were analyzed for a suite of volatile organic compounds. The solvent 1,1-dichloroethane (the same solvent detected in the ground-water monitoring system at the landfill) was detected in a sample from a drive-point well downgradient from the landfill--an indication of the potential risk of landfill-derived contamination migrating toward Big Black Creek. No distinguishing trend or pattern of contamination was identified that could be attributed solely to landfill activities. Landfill activities did not appear to contribute significant contamination to Big Black Creek during these streamflow conditions. Any contaminant contribution from coal-mining activities in the basin may have served to mask any leachate contributions from the landfill; however, the overall effects on stream water and benthic intervebrate communities apparently were only minimal.

Hydrogeology, water quality, and water-resources development potential of the upper Floridan Aquifer in the Valdosta area, south-central Georgia

USGS Publications Warehouse

McConnell, J.B.; Hacke, C.M.

1993-01-01

Water quality in the Upper Floridan aquifer in the Valdosta, Georgia area is adversely affected by direct recharge from the Withlacoochee River. Water enters the aquifer along a short reach of the river where sinkholes have formed in the stream bed. The water receives little filtration as it recharges the Upper Floridan aquifer through these sinkholes. Naturally occurring organic material in the river provides a readily available source of energy for the growth of microbiota in the aquifer. Microbiological processes and chemical reactions in the aquifer produce methane and hydrogen sulfide as the water from the river mixes with ground water and moves downgradient in the aquifer. Humic substances associated with the organic material in the ground water in this area can form trihalomethanes when the water is chlorinated for public supply. To assess areas most suitable for ground-water supply development, areal distributions of total organic carbon, total sulfide, and methane in the Upper Floridan aquifer were mapped and used to evaluate areas affected by recharge from the Withlacoochee River. Areas where concentrations of total organic carbon, total sulfide, and methane were less than or equal to 2.0 milligrams per liter, 0.5 milligrams per liter, and 100 micrograms per liter, respectively, were considered to be relatively unaffected by recharge from the river and to have the greatest potential for water- resources development.

Evaluation of increases in dissolved solids in ground water, Stovepipe Wells Hotel, Death Valley National Monument, California

USGS Publications Warehouse

Buono, Anthony; Packard, E.M.

1982-01-01

Increases in dissolved solids have been monitored in two observation wells near Stovepipe Wells Hotel, Death Valley National Monument, California. One of the hotel 's supply wells delivers water to a reverse-osmosis treatment plant that produces the area 's potable water supply. Should water with increased dissolved solids reach the supply well, the costs of production of potable water will increase. The reverse-osmosis plant supply well is located about 0.4 mile south of one of the wells where increases have been monitored, and 0.8 mile southwest of the well where the most significant increases have been monitored. The direction of local ground-water movement is eastward, which reduces the probability of the supply well being affected. Honey mesquite, a phreatophyte located about 1.5 miles downgradient from the well where the most significant increases have been monitored, might be adversely affected should water with increased dissolved solids extend that far. Available data and data collected during this investigation do not indicate the source of the dissolved-solids increases. Continued ground-water-quality monitoring of existing wells and the installation of additional wells for water-quality monitoring would be necessary before the area affected by the increases, and the source and direction of movement of the water with increased dissolved solids, can be determined. (USGS)

Reconnaissance of geology and water resources along the north flank of the Sweet Grass Hills, north-central Montana

USGS Publications Warehouse

Tuck, L.K.

1993-01-01

Mississippian through Holocene rocks crop out in the area. Emplaced Tertiary igneous rocks have caused structural deformation. Aquifers are Holocene alluvium, Quaternary interstratified sand and gravel, and Upper Cretaceous Judith River Formation and Virgelle Sandstone Member of Eagle Sandstone. Recharge to each aquifer is through combinations of infiltration of precipitation, streamflow, irrigation return flow, stored surface water, and subsurface inflow. Discharge is through combinations of seepage to streams, withdrawals from wells, flow of springs and seeps, evapotranspiration, and subsurface outflow. Water in alluvium flows sub- parallel to stream channels. One water sample had a dissolved-solids concentration of 439 milligrams per liter. Water in the interstratified sand and gravel generally moves northward. Transmissivity was estimated at 900 feet squared per day. Dissolved- solids concentration ranged from 154 to 1,600 milligrams per liter. Water quality is least feasible for irrigation, marginal for domestic use, and generally suitable for livestock. Water in the Judith River Formation probably flows northeast and southeast. One water sample had a dissolved-solids concentration of 855 milligrams per liter. Water in the Virgelle Sandstone Member generally flows north. Transmissivity ranges from 200 to 3,700 feet squared per day. Dissolved-solids concentration ranged from 213 to 1,360 milligrams per liter. Water quality near outcrops is mostly adequate for domestic and livestock use and marginal for irrigation, but deteriorates downgradient. Unknown perennial yields and water quality could limit development of this resource. Miners Coulee, Breed Creek, and Bear Gulch flow intermittently. Dissolved-solids concentration ranged from 241 to 774 milligrams per liter.

Simulation of advective flow under steady-state and transient recharge conditions, Camp Edwards, Massachusetts Military Reservation, Cape Cod, Massachusetts

USGS Publications Warehouse

Walter, Donald A.; Masterson, John P.

2003-01-01

The U.S. Geological Survey has developed several ground-water models in support of an investigation of ground-water contamination being conducted by the Army National Guard Bureau at Camp Edwards, Massachusetts Military Reservation on western Cape Cod, Massachusetts. Regional and subregional steady-state models and regional transient models were used to (1) improve understanding of the hydrologic system, (2) simulate advective transport of contaminants, (3) delineate recharge areas to municipal wells, and (4) evaluate how model discretization and time-varying recharge affect simulation results. A water-table mound dominates ground-water-flow patterns. Near the top of the mound, which is within Camp Edwards, hydraulic gradients are nearly vertically downward and horizontal gradients are small. In downgradient areas that are further from the top of the water-table mound, the ratio of horizontal to vertical gradients is larger and horizontal flow predominates. The steady-state regional model adequately simulates advective transport in some areas of the aquifer; however, simulation of ground-water flow in areas with local hydrologic boundaries, such as ponds, requires more finely discretized subregional models. Subregional models also are needed to delineate recharge areas to municipal wells that are inadequately represented in the regional model or are near other pumped wells. Long-term changes in recharge rates affect hydraulic heads in the aquifer and shift the position of the top of the water-table mound. Hydraulic-gradient directions do not change over time in downgradient areas, whereas they do change substantially with temporal changes in recharge near the top of the water-table mound. The assumption of steady-state hydraulic conditions is valid in downgradient area, where advective transport paths change little over time. In areas closer to the top of the water-table mound, advective transport paths change as a function of time, transient and steady-state paths do not coincide, and the assumption of steady-state conditions is not valid. The simulation results indicate that several modeling tools are needed to adequately simulate ground-water flow at the site and that the utility of a model varies according to hydrologic conditions in the specific areas of interest.

Effects of highway deicing chemicals on shallow unconsolidated aquifers in Ohio, interim report, 1988-93

USGS Publications Warehouse

Jones, A.L.; Sroka, B.N.

1997-01-01

Effects of the application of highway deicing chemicals during winter months on ground- water quality are being studied by the U.S. Geological Survey in cooperation with the Ohio Department of Transportation and the Federal Highway Administration. Eight sites throughout the State were selected along major undivided highways where drainage is by open ditches and ground-water flow is approximately perpendicular to the highway. At these sites, records of deicer application rates are being kept and apparent movement of deicing chemicals through shallow, unconsolidated aquifers is being monitored by means of periodic measurements of specific con ductance and concentrations of dissolved sodium, calcium, and chloride. The counties and corre sponding sections of state routes being monitored are the following: State Route (SR) 3 in Ashland County, SR 84 in Ashtabula County, SR 29 in Champaign County, SR 4 in Clark County, SR 2 in Lucas County, SR 104 in Pickaway County, SR 14 in Portage County, and SR 97 in Richland County. The study began in January 1988 with background data collection, extensive literature review, and site selection. This process, including drilling of wells at the eight selected sites, lasted 3 years. Routine ground-water sampling at 4- to 6-week intervals began in January 1991. A relatively new type of multilevel, passive flow ground-water sampling device was constructed and used. Other conditions monitored on a regular basis included ground-water level (monitored con tinuously), specific conductance, air and soil temperature, precipitation, chloride concentration in soil samples, ground conductivity, and deicing chemical application times and rates. For the interim reporting period, water samples were collected from January 1991 through September 1993. Evidence from water analysis, specific conductance measurements, and surface geophysical measurements indicates that four of the eight sites (Ashtabula County, Lucas County, Portage County, and Richland County sites) are potentially affected by direct application of deic ing chemicals. Climatic data from the period January 1991 through September 1993 show that cold weather, and therefore deicing chemical application rates, varied widely across the State. As a consequence, only minor traces of dissolved chloride above background concentrations (mean, 12-25 mg/L) were determined in ground-water samples from the Pickaway County, Clark County, and Champaign County sites. At the Ashland and Richland County sites, dissolved chlo ride concentrations increased above background concentrations (from the upgradient well, pre sumably unaffected by road salt) only intermittently (mean background concentrations of 3-25 mg/L, rising to a mean of 49-77 mg/L). For the interim reporting period, the mean dissolved chloride concentration for all downgradient wells was about 2 times the background concentra tion (25mg/L) at the Ashland County site (50 mg/L) and 14 times the background concentration (3 mg/L) at the Richland County site (40 mg/L). At the Lucas County, Portage County, and Ash tabula County sites, deicing-chemical application was consistent throughout the winter, and downgradient dissolved chloride concentrations rarely returned to background concentrations (mean 6-32 mg/L) throughout the period. For the interim reporting period, the mean dissolved chloride concentration for all downgradient wells was about 3 times the background concentra tion at the Lucas County site (92 mg/L), 72 times the background concentration at the Portage County site (432 mg/L, 2 downgradient wells), and 21 times the background concentration at the Ashtabula County site (279 mg/L). Other factors that may affect the movement of deicing chemicals through the aquifer were examined, such as precipitation amounts; the types of subsurface materials; ground-water velocity and gradient; hydraulic conductivity; soil type; land use; and ODOT deicing priority. A final report is planned for 2001 afte

Environmental fate of Ra in cation-exchange regeneration brine waste disposed to septic tanks, New Jersey Coastal Plain, USA: migration to the water table.

PubMed

Szabo, Zoltan; Jacobsen, Eric; Kraemer, Thomas F; Parsa, Bahman

2010-01-01

Fate of radium (Ra) in liquid regeneration brine wastes from water softeners disposed to septic tanks in the New Jersey Coastal Plain was studied. Before treatment, combined Ra ((226)Ra plus (228)Ra) concentrations (maximum, 1.54 Bq L(-1)) exceeded the 0.185 Bq L(-1) Maximum Contaminant Level in 4 of 10 studied domestic-well waters (median pH, 4.90). At the water table downgradient from leachfields, combined Ra concentrations were low (commonly < or =0.019 Bq L(-1)) when pH was >5.3, indicating sequestration; when pH was < or =5.3 (acidic), concentrations were elevated (maximum, 0.985 Bq L(-1) - greater than concentrations in corresponding discharged septic-tank effluents (maximum, 0.243 Bq L(-1))), indicating Ra mobilization from leachfield sediments. Confidence in quantification of Ra mass balance was reduced by study design limitations, including synoptic sampling of effluents and ground waters, and large uncertainties associated with analytical methods. The trend of Ra mobilization in acidic environments does match observations from regional water-quality assessments.

In Situ Bioremediation of MTBE in Groundwater

DTIC Science & Technology

2003-06-01

by-products (carbon dioxide and water ). Groundwater leaving the down-gradient edge of the treatment zone contains MTBE at concentrations less than... groundwater treatment approaches ineffective or impracticable. Currently, conventional pump and treat (P&T) followed by aboveground water treatment and...carbon dioxide and water ). Groundwater leaving the down gradient edge of the treatment zone contains MTBE at concentrations less than or equal to the

Distribution and mass loss of volatile organic compounds in the surficial aquifer at sites FT03, LF13, and WP14/LF15, Dover Air Force Base, Delaware, November 2000-February 2001

USGS Publications Warehouse

Barbaro, Jeffrey R.; Neupane, Pradumna P.

2002-01-01

Ground-water and surface-water sampling was conducted in the natural attenuation study area in the East Management Unit of Dover Air Force Base, Delaware to determine the distributions of volatile organic compounds in the vicinity of four sites?Fire Training Area Three, the Rubble Area Landfill, the Receiver Station Landfill, and the Liquid Waste Disposal Landfill. This work was done by the U.S. Geological Survey, in cooperation with the U.S. Air Force, as part of an ongoing assessment of the effectiveness of natural attenuation at these sites. The specific objectives of the study were to (1) determine the areal and vertical extent of the contaminant plumes and source areas, (2) measure volatile organic compound concentrations in ground-water discharge areas and in surface water under base-flow conditions, (3) evaluate the potential for off-site migration of the mapped plumes, and (4) estimate the amount of mass loss downgradient of the Liquid Waste Disposal and Receiver Station Landfills. A direct-push drill rig and previously installed multi-level piezometers were used to determine the three-dimensional distributions of volatile organic compounds in the 30?60-foot-thick surficial aquifer underlying the natural attenuation study area. A hand -driven mini-piezometer was used to collect ground-water samples in ground-water discharge areas. A total of 319 ground-water and 4 surface-water samples were collected from November 2000 to February 2001 and analyzed for chlorinated solvents and fuel hydrocarbons. The contaminant plumes migrating from Fire Training Area Three and the Rubble Area Landfill are approximately 500 feet and 800 feet, respectively, in length. These plumes consist predominantly of cis-1,2-dichloroethene, a daughter product, indicating that extensive dechlorination of tetrachloroethene and trichloroethene has occurred at these sites. With an approximate length of 2,200 feet, the plume migrating from the Receiver Station and Liquid Waste Disposal Landfills is the largest of the three plumes in the East Management Unit. In this plume, the parent compounds, tetrachloroethene and trichloroethene, as well as cis-1,2-dichloroethene, are present downgradient of the source. Vinyl chloride was not detected in the natural attenuation study area. Vertical water-quality profiles indicate that volatile organic compounds are present mainly in the upper part of the surficial aquifer. Plumes of fuel hydrocarbon constituents were not detected in the natural attenuation study area. Volatile organic compounds were present at concentrations above detection limits in 6 of 14 samples collected from the aquifer underlying the bed of Pipe Elm Branch and the drainage ditch adjacent to Fire Training Area Three, indicating that the plumes migrating from Fire Training Area Three and the Receiver Station and Liquid Waste Disposal Landfills are reaching these ground-water discharge areas. In contrast, sampling results indicated that the plume from the Rubble Area Landfill does not reach these ground-water discharge areas. Trichloroethene was present above detection limits in one of four surface-water samples collected from Pipe Elm Branch and the drainage ditch adjacent to Fire Training Area Three. The trichloroethene concentration is below applicable Delaware Department of Natural Resources and Environmental Control surface-water-quality standards for human health. An assessment of chlorinated-solvent mass loss in the plume migrating from the Receiver Station and Liquid Waste Disposal Landfills indicates that tetrachloroethene and trichloroethene mass loss downgradient of the source is negligible. Cis-1,2-dichloroethene, however, appears to biodegrade by an unidentified reaction in the plume. Plan-view maps of the plume migrating from the Receiver Station and Liquid Waste Disposal Landfills indicate that tetrachloroethene, trichloroethene, and cis-1,2-dichloroethene may migrate off Dover Air Force Base property approximately 1,500 f

Remediation System Evaluation, Shorco South, Mahwah, New Jersey

EPA Pesticide Factsheets

The Shorco South site is located on the southbound side of Route 17 in the Township of Mahwah, New Jersey. The Shorco South site is downgradient of the Shorco North site, which also has ground water impacted with petroleum constituents.

Hydrologic conditions, groundwater quality, and analysis of sink hole formation in the Albany area of Dougherty County, Georgia, 2009

USGS Publications Warehouse

Gordon, Debbie W.; Painter, Jaime A.; McCranie, John M.

2012-01-01

The U.S. Geological Survey, in cooperation with the Albany Water, Gas, and Light Commission has conducted water resources investigations and monitored groundwater conditions and availability in the Albany, Georgia, area since 1977. This report presents an overview of hydrologic conditions, water quality, and groundwater studies in the Albany area of Dougherty County, Georgia, during 2009. Historical data also are presented for comparison with 2009 data. During 2009, groundwater-level data were collected in 29 wells in the Albany area to monitor water-level trends in the surficial, Upper Floridan, Claiborne, Clayton, and Providence aquifers. Groundwater-level data from 21 of the 29 wells indicated an increasing trend during 2008–09. Five wells show no trend due to lack of data and three wells have decreasing trends. Period-of-record water levels (period of record ranged between 1957–2009 and 2003–2009) declined slightly in 10 wells and increased slightly in 4 wells tapping the Upper Floridan aquifer; declined in 1 well and increased in 2 wells tapping the Claiborne aquifer; declined in 4 wells and increased in 2 wells tapping the Clayton aquifer; and increased in 1 well tapping the Providence aquifer. Analyses of groundwater samples collected during 2009 from 12 wells in the Upper Floridan aquifer in the vicinity of a well field located southwest of Albany indicate that overall concentrations of nitrate plus nitrite as nitrogen increased slightly from 2008 in 8 wells. A maximum concentration of 12.9 milligrams per liter was found in a groundwater sample from a well located upgradient from the well field. The distinct difference in chemical constituents of water samples collected from the Flint River and samples collected from wells located in the well-field area southwest of Albany indicates that little water exchange occurs between the Upper Floridan aquifer and Flint River where the river flows adjacent to, but downgradient of, the well field. Water-quality data collected during 2008 from two municipal wells located in northern Albany and downgradient from a hazardous waste site indicate low-level concentrations of pesticides in one of the wells; however, no pesticides were detected in samples collected during 2009. Detailed geologic cross sections were used to create a three-dimensional, hydrogeologic diagram of the well field southwest of Albany in order to examine the occurrence of subsurface features conducive to sinkhole formation. Monitored groundwater-level data were used to assess the possible relations between sinkhole formation, precipitation, and water levels in the Upper Floridan aquifer. Although the water levels in well 12L382 oscillated above and below the top of the aquifer on a regular basis between 2007 and 2009, sinkhole development did not appear to correlate directly with either well-field pumping or water levels in the Upper Floridan aquifer. Specifically, two sinkholes formed in each of the years 2003 and 2005 when water levels were almost 20 feet above the top of the aquifer during most of the year. Water-level and sinkhole-formation data continue to be collected to allow further study and analysis.

Hydrogeology, water quality, and potential for transport of organochlorine pesticides in ground water at the North Hollywood Dump, Memphis, Tennessee

USGS Publications Warehouse

Broshears, R.E.; Bradley, M.W.

1992-01-01

Geologic, hydrologic, and water-quality data indicate that ground-water contamination is confined to shallow horizons within the unconfined aquifer underlying the North Hollywood Dump in Memphis, Tennessee. The dump is a closed municipal-industrial landfill that has been ranked as Tennessee's potentially most dangerous hazardous-waste site. Toxic constituents of concern at the dump include residues from the manufacture of organochlorine pesticides. The dump overlies an unconfined aquifer of unconsolidated sands, silts, and clays. During average hydrologic conditions, ground waterflows beneath the dump at a mean velocity of approximately 3 feet per day and discharges to the Wolf River. Leachate from the dump mixes with underlying ground water, resulting in increased concentrations of dissolved solids and organic carbon downgradient from the dump. The mobility of chlordane, a representative organochlorine pesticide, is limited by its low solubility and its strong affinity for sand, silt, and clays of the aquifer. Degradation of chlordane may occur slowly, if at all, in the aquifer. Based on estimates of mean ground-water velocity and retardation of the pesticide due to sorption, mean travel times for chlordane migrating from the dump to the ground-water discharge zone are of the order of 50 to 500 years. Simulations of chlordane concentration resulting from the discharge of contaminated ground water and complete mixing in the Wolf River are sensitive to assumptions about chlordane persistence in the unconfined aquifer. If the half life of chlordane in the aquifer is assumed to be 30 years or less, the simulated concentration of chlordane in the Wolf River under average flow conditions is less than the most stringent water-quality criterion.

Methane oxidation in a crude oil contaminated aquifer: Delineation of aerobic reactions at the plume fringes

USGS Publications Warehouse

Amos, R.T.; Bekins, B.A.; Delin, G.N.; Cozzarelli, I.M.; Blowes, D.W.; Kirshtein, J.D.

2011-01-01

High resolution direct-push profiling over short vertical distances was used to investigate CH4 attenuation in a petroleum contaminated aquifer near Bemidji, Minnesota. The contaminant plume was delineated using dissolved gases, redox sensitive components, major ions, carbon isotope ratios in CH4 and CO2, and the presence of methanotrophic bacteria. Sharp redox gradients were observed near the water table. Shifts in ??13CCH4 from an average of - 57.6??? (?? 1.7???) in the methanogenic zone to - 39.6??? (?? 8.7???) at 105 m downgradient, strongly suggest CH4 attenuation through microbially mediated degradation. In the downgradient zone the aerobic/anaerobic transition is up to 0.5 m below the water table suggesting that transport of O2 across the water table is leading to aerobic degradation of CH4 at this interface. Dissolved N2 concentrations that exceeded those expected for water in equilibrium with the atmosphere indicated bubble entrapment followed by preferential stripping of O2 through aerobic degradation of CH4 or other hydrocarbons. Multivariate and cluster analysis were used to distinguish between areas of significant bubble entrapment and areas where other processes such as the infiltration of O 2 rich recharge water were important O2 transport mechanisms. ?? 2011 Elsevier B.V. All rights reserved.

INFLUENCE OF STRATIGRAPHY ON A DIVING MTBE PLUME AND ITS CHARACTERIZATION: A CASE STUDY

EPA Science Inventory

Conventional conceptual models applied at petroleum release sites are often based on assumptions of vertical contaminant migration through the vadose zone followed by horizontal, downgradient transport at the water table with limited, if any, additional downward migration. Howev...

IDENTIFYING AND PREDICTING DIVING PLUME BEHAVIOR AT GROUNDWATER SITES CONTAMINATED WITH MTBE: PART 2

EPA Science Inventory

As contaminant ground water flows downgradient from a release point, its movement is dictated by site geological conditions and hydraulics that may result in significant perpendicular contamination migration. This vertical migration pattern has been termed 'plume diving'. Under ...

40 CFR 258.55 - Assessment monitoring program.

Code of Federal Regulations, 2013 CFR

2013-07-01

... upgradient edge of the MSWLF unit and downgradient monitoring well screen (minimum distance of travel); (5... effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or mutation. (ii) [Reserved] (j) In establishing ground-water protection...

40 CFR 258.55 - Assessment monitoring program.

Code of Federal Regulations, 2011 CFR

2011-07-01

... upgradient edge of the MSWLF unit and downgradient monitoring well screen (minimum distance of travel); (5... effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or mutation. (ii) [Reserved] (j) In establishing ground-water protection...

40 CFR 258.55 - Assessment monitoring program.

Code of Federal Regulations, 2012 CFR

2012-07-01

... upgradient edge of the MSWLF unit and downgradient monitoring well screen (minimum distance of travel); (5... effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or mutation. (ii) [Reserved] (j) In establishing ground-water protection...

Mercury speciation and mobilization in a wastewater-contaminated groundwater plume

USGS Publications Warehouse

Lamborg, Carl H.; Kent, Doug B.; Swarr, Gretchen J.; Munson, Kathleen M.; Kading, Tristan; O'Connor, Alison E.; Fairchild, Gillian M.; LeBlanc, Denis R.; Wiatrowski, Heather A.

2013-01-01

We measured the concentration and speciation of mercury (Hg) in groundwater down-gradient from the site of wastewater infiltration beds operated by the Massachusetts Military Reservation, western Cape Cod, Massachusetts. Total mercury concentrations in oxic, mildly acidic, uncontaminated groundwater are 0.5–1 pM, and aquifer sediments have 0.5–1 ppb mercury. The plume of impacted groundwater created by the wastewater disposal is still evident, although inputs ceased in 1995, as indicated by anoxia extending at least 3 km down-gradient from the disposal site. Solutes indicative of a progression of anaerobic metabolisms are observed vertically and horizontally within the plume, with elevated nitrate concentrations and nitrate reduction surrounding a region with elevated iron concentrations indicating iron reduction. Mercury concentrations up to 800 pM were observed in shallow groundwater directly under the former infiltration beds, but concentrations decreased with depth and with distance down-gradient. Mercury speciation showed significant connections to the redox and metabolic state of the groundwater, with relatively little methylated Hg within the iron reducing sector of the plume, and dominance of this form within the higher nitrate/ammonium zone. Furthermore, substantial reduction of Hg(II) to Hg0 within the core of the anoxic zone was observed when iron reduction was evident. These trends not only provide insight into the biogeochemical factors controlling the interplay of Hg species in natural waters, but also support hypotheses that anoxia and eutrophication in groundwater facilitate the mobilization of natural and anthropogenic Hg from watersheds/aquifers, which can be transported down-gradient to freshwaters and the coastal zone.

Field Testing of Downgradient Uranium Mobility at an In-Situ Recovery Uranium Mine

NASA Astrophysics Data System (ADS)

Reimus, P. W.; Clay, J. T.; Rearick, M.; Perkins, G.; Brown, S. T.; Basu, A.; Chamberlain, K.

2015-12-01

In-situ recovery (ISR) mining of uranium involves the injection of O2 and CO2 (or NaHCO3) into saturated roll-front deposits to oxidize and solubilize the uranium, which is then removed by ion exchange at the surface and processed into U3O8. While ISR is economical and environmentally-friendly relative to conventional mining, one of the challenges of extracting uranium by this process is that it leaves behind a geochemically-altered aquifer that is exceedingly difficult to restore to pre-mining geochemical conditions, a regulatory objective. In this research, we evaluated the ability of the aquifer downgradient of an ISR mining area to attenuate the transport of uranium and other problem constituents that are mobilized by the mining process. Such an evaluation can help inform both regulators and the mining industry as to how much restoration of the mined ore zone is necessary to achieve regulatory compliance at various distances downgradient of the mining zone even if complete restoration of the ore zone proves to be difficult or impossible. Three single-well push-pull tests and one cross-well test were conducted in which water from an unrestored, previously-mined ore zone was injected into an unmined ore zone that served as a geochemical proxy for the downgradient aquifer. In all tests, non-reactive tracers were injected with the previously-mined ore zone water to allow the transport of uranium and other constituents to be compared to that of the nonreactive species. In the single-well tests, it was shown that the recovery of uranium relative to the nonreactive tracers ranged from 12-25%, suggesting significant attenuation capacity of the aquifer. In the cross-well test, selenate, molybdate and metavanadate were injected with the unrestored water to provide information on the transport of these potentially-problematic anionic constituents. In addition to the species-specific transport information, this test provided valuable constraints on redox conditions within the system, as redox couples involving these species collectively bracket the predicted transition redox potential for the U(VI)/U(IV) couple. Reduction should provide much longer-lasting immobilization of constituents than adsorption, especially given the inherent reducing characteristics of roll-front systems.

Groundwater response to changing water-use practices in sloping aquifers using convolution of transient response functions

USDA-ARS?s Scientific Manuscript database

This study examines the impact of a sloping base on the movement of transients through groundwater systems. Dimensionless variables and regression of model results are employed to develop functions relating the transient change in saturated thickness to the distance upgradient and downgradient from ...

Displacement of soil pore water by trichloroethylene

USGS Publications Warehouse

Wershaw, R. L.; Aiken, G.R.; Imbrigiotta, T.E.; Goldberg, M.C.

1994-01-01

Dense nonaqueous phase liquids (DNAPLS) are important pollutants because of their widespread use as chemical and industrial solvents. An example of the pollution caused by the discharge of DNAPLs is found at the Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has been discharged directly into the unsaturated zone. This discharge has resulted in the formation of a plume of TCE-contaminated water in the aquifer downgradient of the discharge. A zone of dark-colored groundwater containing a high dissolved organic C content has been found near the point of discharge of the TCE. The colored-water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic acids isolated from the colored-waters plume, from water from a background well that has not been affected by the discharge of chlorinated solvents, and from soil pore water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compared. Nuclear magnetic resonance spectra of the fulvic acids from the colored waters and from the lysimeter are very similar, but are markedly different from the nuclear magnetic resonance spectrum of the fulvic acid from the background well. The three-dimensional fluorescence spectrum and the DOC fractionation profile of the colored groundwater and the soil pore water are very similar to each other, but quite different from those of the background water. It is proposed from these observations that this colored water is soil pore water that has been displaced by a separate DNAPL liquid phase downward to the saturated zone.

234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of Yucca Mountain, Nevada, USA

USGS Publications Warehouse

Paces, J.B.; Ludwig, K. R.; Peterman, Z.E.; Neymark, L.A.

2002-01-01

Uranium concentrations and 234U/238U ratios in saturated-zone and perched ground water were used to investigate hydrologic flow and downgradient dilution and dispersion in the vicinity of Yucca Mountain, a potential high-level radioactive waste disposal site. The U data were obtained by thermal ionization mass spectrometry on more than 280 samples from the Death Valley regional flow system. Large variations in both U concentrations (commonly 0.6-10 ??g 1-1) and 234U/238U activity ratios (commonly 1.5-6) are present on both local and regional scales; however, ground water with 234U/238U activity ratios from 7 up to 8.06 is restricted largely to samples from Yucca Mountain. Data from ground water in the Tertiary volcanic and Quaternary alluvial aquifers at and adjacent to Yucca Mountain plot in 3 distinct fields of reciprocal U concentration versus 234U/238U activity ratio correlated to different geographic areas. Ground water to the west of Yucca Mountain has large U concentrations and moderate 234U/238U whereas ground water to the east in the Fortymile flow system has similar 234U/238U, but distinctly smaller U concentrations. Ground water beneath the central part of Yucca Mountain has intermediate U concentrations but distinctive 234U/238U activity ratios of about 7-8. Perched water from the lower part of the unsaturated zone at Yucca Mountain has similarly large values of 234U/238U. These U data imply that the Tertiary volcanic aquifer beneath the central part of Yucca Mountain is isolated from north-south regional flow. The similarity of 234U/238U in both saturated- and unsaturated-zone ground water at Yucca Mountain further indicates that saturated-zone ground water beneath Yucca Mountain is dominated by local recharge rather than regional flow. The distinctive 234U/238U signatures also provide a natural tracer of downgradient flow. Elevated 234U/238U in ground water from two water-supply wells east of Yucca Mountain are interpreted as the result of induced flow from 40 a of ground-water withdrawal. Elevated 234U/238U in a borehole south of Yucca Mountain is interpreted as evidence that natural downgradient flow is more likely to follow southerly paths in the structurally anisotropic Tertiary volcanic aquifer where it becomes diluted by regional flow in the Fortymile system.

Predicted water-level and water-quality effects of artificial recharge in the Upper Coachella Valley, California, using a finite-element digital model

USGS Publications Warehouse

Swain, Lindsay A.

1978-01-01

From 1936 to 1974, water levels declined more than 100 feet in the Palm Springs area and 60 feet in the Palm Desert area of the upper Coachella Valley, Calif. Water from the Colorado River Aqueduct is presently being recharged to the basin. The dissolved-solids concentration of native ground water in the recharge area is about 210 mg/liter and that of recharge water ranges from 600 to 750 mg/liter. A finite-element model indicates that without recharge the 1974 water levels in the Palm Springs area will decline 200 feet by the year 2000 because of pumpage. If the aquifer is recharged at a rate from about 7 ,500 acre-feet per year in 1973 increasing to 61,200 acre-feet per year in 1990 and thereafter, the water level in the Palm Springs area will decline about 20 feet below the 1974 level by 1991 and recover to the 1974 level by 2000. The solute-transport finite-element model of the recharge area indicates that the artificial recharge plume (bounded by the 300-mg/liter line) will move about 1.1 miles downgradient of the recharge ponds by 1981 and about 4.5 miles from the ponds by 2000. 

Degradation of phenolic contaminants in ground water by anaerobic bacteria: St. Louis Park, Minnesota

USGS Publications Warehouse

Ehrlich, G.G.; Goerlitz, D.F.; Godsy, E.M.; Hult, M.F.

1982-01-01

Coal-tar derivatives from a coal-tar distillation and wood-treating plant that operated from 1918 to 1972 at St. Louis Park, Minnesota contaminated the near-surface ground water. Solutions of phenolic compounds and a water-immiscible mixture of polynuclear aromatic compounds accumulated in wetlands near the plant site and entered the aquifer. The concentration of phenolic compounds in the aqueous phase under the wetlands is about 30 mg/1 but decreases to less than 0.2 mg/1 at a distance of 430 m immediately downgradient from the source. Concentrations of naphthalene (the predominant polynuclear compound in the ground water) and sodium (selected as a conservative tracer) range from about 20 mg/1 and 430 mg/1 in the aqueous phase at the source to about 2 mg/1 and 120 mg/1 at 430 m downgradient, respectively. Phenolic compounds and naphthalene are disappearing faster than expected if only dilution were occurring. Sorption of phenolic compounds on aquifer sediments is negligible but naphthalene is slightly sorbed. Anaerobic biodegradation of phenolic compounds is primarily responsible for the observed attenuation. Methane was found only in water samples from the contaminated zone (2-20 mg/1). Methane-producing bacteria were found only in water from the contaminated zone. Methane was produced in laboratory cultures of contaminated water inoculated with bacteria from the contaminated zone. Evidence for anaerobic biodegradation of naphthalene under either field or laboratory conditions was not obtained.

Potential aquifer vulnerability in regions down-gradient from uranium in situ recovery (ISR) sites.

PubMed

Saunders, James A; Pivetz, Bruce E; Voorhies, Nathan; Wilkin, Richard T

2016-12-01

Sandstone-hosted roll-front uranium ore deposits originate when U(VI) dissolved in groundwater is reduced and precipitated as insoluble U(IV) minerals. Groundwater redox geochemistry, aqueous complexation, and solute migration are important in leaching uranium from source rocks and transporting it in low concentrations to a chemical redox interface where it is deposited in an ore zone typically containing the uranium minerals uraninite, pitchblende, and/or coffinite; various iron sulfides; native selenium; clays; and calcite. In situ recovery (ISR) of uranium ores is a process of contacting the uranium mineral deposit with leaching and oxidizing (lixiviant) fluids via injection of the lixiviant into wells drilled into the subsurface aquifer that hosts uranium ore, while other extraction wells pump the dissolved uranium after dissolution of the uranium minerals. Environmental concerns during and after ISR include water quality degradation from: 1) potential excursions of leaching solutions away from the injection zone into down-gradient, underlying, or overlying aquifers; 2) potential migration of uranium and its decay products (e.g., Ra, Rn, Pb); and, 3) potential mobilization and migration of redox-sensitive trace metals (e.g., Fe, Mn, Mo, Se, V), metalloids (e.g., As), and anions (e.g., sulfate). This review describes the geochemical processes that control roll-front uranium transport and fate in groundwater systems, identifies potential aquifer vulnerabilities to ISR operations, identifies data gaps in mitigating these vulnerabilities, and discusses the hydrogeological characterization involved in developing a monitoring program. Published by Elsevier Ltd.

Study of contaminant transport at an open-tipping waste disposal site.

PubMed

Ashraf, Muhammad Aqeel; Yusoff, Ismail; Yusof, Mohamad; Alias, Yatimah

2013-07-01

Field and laboratory studies were conducted to estimate concentration of potential contaminants from landfill in the underlying groundwater, leachate, and surface water. Samples collected in the vicinity of the landfill were analyzed for physiochemical parameters, organic contaminants, and toxic heavy metals. Water quality results obtained were compared from published data and reports. The results indicate serious groundwater and surface water contamination in and around the waste disposal site. Analysis of the organic samples revealed that the site contains polychlorinated biphenyls and other organo-chlorine chemicals, principally chloro-benzenes. Although the amount of PCB concentration discovered was not extreme, their presence indicates a potentially serious environmental threat. Elevated concentrations of lead, copper, nickel, manganese, cadmium, and cobalt at the downgradient indicate that the contamination plume migrated further from the site, and the distribution of metals and metals containing wastes in the site is nonhomogeneous. These results clearly indicate that materials are poorly contained and are at risk of entering the environment. Therefore, full characterization of the dump contents and the integrity of the site are necessary to evaluate the scope of the problem and to identify suitable remediation options.

Evaluation of the fate and transport of chlorinated ethenes in a complex groundwater system discharging to a stream in Wonju, Korea

NASA Astrophysics Data System (ADS)

Lee, Seong-Sun; Kaown, Dugin; Lee, Kang-Kun

2015-11-01

Chlorinated ethenes such as trichloroethylene (TCE) are common and persistent groundwater contaminants. If contaminated groundwater discharges to a stream, then stream water pollution near the contamination site also becomes a problem. In this respect, the fate and transport of chlorinated ethenes around a stream in an industrial complex were evaluated using the concentration of each component, and hydrogeochemical, microbial, and compound-specific carbon isotope data. Temporal and spatial monitoring reveal that a TCE plume originating from main and local source zones continues to be discharged to a stream. Groundwater geochemical data indicate that aerobic conditions prevail in the upgradient area of the studied aquifer, whereas conditions become anaerobic in the downgradient. The TCE molar fraction is high at the main and local source zones, ranging from 87.4 to 99.2% of the total volatile organic compounds (VOCs). An increasing trend in the molar fraction of cis-1, 2-Dichloroethene (cis-DCE) and vinyl chloride (VC) was observed in the downgradient zone of the study area. The enriched δ13C values of TCE and depleted values of cis-DCE in the stream zone, compared to those of the source zone, also suggest biodegradation of VOCs. Microbial community structures in monitoring wells adjacent to the stream zone in the downgradient area were analyzed using 16S rRNA gene-based pyrosequencing to identify the microorganisms responsible for biodegradation. This was attributed to the high relative abundance of dechlorinating bacteria in monitoring wells under anaerobic conditions farthest from the stream in the downgradient area. The multilateral approaches adopted in this study, combining hydrogeochemical and biomolecular methods with compound-specific analyses, indicate that contaminants around the stream were naturally attenuated by active anaerobic biotransformation processes.

Effect of Water-Table Fluctuations on Source Depletion and Dissolved-Plume Behavior of a Multi-Component Light Nonaqueous-Phase Liquid

NASA Astrophysics Data System (ADS)

Dobson, R.; Schroth, M. H.; Zeyer, J.

2006-12-01

Light nonaqueous-phase liquids (LNAPLs) such as gasoline and diesel are among the most common soil and groundwater contaminants. Dissolution and subsequent advective transport of LNAPL components can negatively impact downgradient water supplies, while biodegradation is commonly thought to be an important sink for this class of contaminants. Water-table fluctuations, either naturally occurring or intentionally induced, may affect LNAPL component transport and biodegradation in aquifers. We present a laboratory investigation of the effect of water-table fluctuations on the dissolution and biodegradation of a multi-component LNAPL in a pair of similar model aquifers, one of which was subjected to a water-table fluctuation. Water-table fluctuation resulted in LNAPL and air entrapment below the water table, an increase in the vertical extent of LNAPL contamination and an increase in the volume of water passing through the contaminated zone. Effluent concentrations of dissolved LNAPL components were higher and those of dissolved nitrate were lower in the aquifer model where a fluctuation had been induced. Thus, water table fluctuation led to enhanced LNAPL dissolution as well as enhanced biodegradation activity. The increase in biodegradation observed after fluctuation was of lesser magnitude than the increase in LNAPL dissolution, such that water-table fluctuations might be expected to result in increased exposure of downgradient receptors to dissolved LNAPL components. Conversely, the potential for free-phase LNAPL migration was reduced following a water-table fluctuation, as LNAPL entrapment by the rising water table reduced the amount of free phase LNAPL. Lateral migration of LNAPL following emplacement was observed in the model aquifer where no fluctuation occurred, but not in the model aquifer where a water-table fluctuation was induced.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.; Environmental Science Division

The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) formerly operated a grain storage facility at Milford, Nebraska. In May 2008, the CCC/USDA directed the Environmental Science Division of Argonne National Laboratory, as its technical consultant, to develop a work plan for a targeted investigation at the Milford site. The purpose of the targeted investigation is to assess the current extent and configuration of the carbon tetrachloride plume downgradient from the former CCC/USDA facility and proximal to the banks of the Big Blue River, which borders the area of concern to the east, southeast, and northeast. In 1995,more » carbon tetrachloride contamination was detected by the Nebraska Department of Health and Human Services in a private drinking water well and a livestock well 1.25 mi south of Milford (Figure 1.1). The Trojan drinking water well is located directly downgradient (approximately 300 ft east) of the former CCC/USDA facility. Low levels of carbon tetrachloride contamination were also found in the Troyer livestock well, approximately 1,200 ft north of the former CCC/USDA facility.« less

Importance of closely spaced vertical sampling in delineating chemical and microbiological gradients in groundwater studies

USGS Publications Warehouse

Smith, R.L.; Harvey, R.W.; LeBlanc, D.R.

1991-01-01

Vertical gradients of selected chemical constituents, bacterial populations, bacterial activity and electron acceptors were investigated for an unconfined aquifer contaminated with nitrate and organic compounds on Cape Cod, Massachusetts, U.S.A. Fifteen-port multilevel sampling devices (MLS's) were installed within the contaminant plume at the source of the contamination, and at 250 and 2100 m downgradient from the source. Depth profiles of specific conductance and dissolved oxygen at the downgradient sites exhibited vertical gradients that were both steep and inversely related. Narrow zones (2-4 m thick) of high N2O and NH4+ concentrations were also detected within the contaminant plume. A 27-fold change in bacterial abundance; a 35-fold change in frequency of dividing cells (FDC), an indicator of bacterial growth; a 23-fold change in 3H-glucose uptake, a measure of heterotrophic activity; and substantial changes in overall cell morphology were evident within a 9-m vertical interval at 250 m downgradient. The existence of these gradients argues for the need for closely spaced vertical sampling in groundwater studies because small differences in the vertical placement of a well screen can lead to incorrect conclusions about the chemical and microbiological processes within an aquifer.Vertical gradients of selected chemical constituents, bacterial populations, bacterial activity and electron acceptors were investigated for an unconfined aquifer contaminated with nitrate and organic compounds on Cape Cod, Massachusetts, USA. Fifteen-port multilevel sampling devices (MLS's) were installed within the contaminant plume at the source of the contamination, and at 250 and 2100 m downgradient from the source. Depth profiles of specific conductance and dissolved oxygen at the downgradient sites exhibited vertical gradients that were both steep and inversely related. Narrow zones (2-4 m thick) of high N2O and NH4+ concentrations were also detected within the contaminant plume. A 27-fold change in bacterial abundance; a 35-fold change in frequency of dividing cells (FDC), an indicator of bacterial growth; a 23-fold change in 3H-glucose uptake, a measure of heterotrophic activity; and substantial changes in overall cell morphology were evident within a 9-m vertical interval at 250 m downgradient. The existence of these gradients argues for the need for closely spaced vertical sampling in ground-water studies because small differences in the vertical placement of a well screen can lead to incorrect conclusions about the chemical and microbiological processes within an aquifer.

Pharmaceuticals and other organic wastewater contaminants within a leachate plume downgradient of a municipal landfill

USGS Publications Warehouse

Barnes, Kimberlee K.; Christenson, Scott C.; Kolpin, Dana W.; Focazio, Michael J.; Furlong, Edward T.; Zaugg, Steven D.; Meyer, Michael T.; Barber, Larry B.

2004-01-01

Ground water samples collected from the Norman Landfill research site in central Oklahoma were analyzed as part of the U.S. Geological Survey (USGS) Toxic Substances Hydrology Program's national reconnaissance of pharmaceuticals and other organic waste water contaminants (OWCs) in ground water. Five sites, four of which are located downgradient of the landfill, were sampled in 2000 and analyzed for 76 OWCs using four research methods developed by the USGS. OWCs were detected in water samples from all of the sites sampled, with 22 of the 76 OWCs being detected at least once. Cholesterol (a plant and animal steroid), was detected at all five sites and was the only compound detected in a well upgradient of the landfill. N,Ndiethyltoluamide (DEET used in insect repellent) and tri(2-chloroethyl) phosphate (fire-retardant) were detected in water samples from all four sites located within the landfill-derived leachate plume. The sites closest to the landfill had more detections and greater concentrations of each of the detected compounds than sites located farther away. Detection of multiple OWCs occurred in the four sites located within the leachate plume, with a minimum of four and a maximum of 17 OWCs detected. Because the landfill was established in the 1920s and closed in 1985, many compounds detected in the leachate plume were likely disposed of decades ago. These results indicate the potential for long-term persistence and transport of some OWCs in ground water.

Near-decadal changes in nitrate and pesticide concentrations in the South Platte River alluvial aquifer, 1993-2004

USGS Publications Warehouse

Paschke, S.S.; Schaffrath, K.R.; Mashbum, S.L.

2008-01-01

The lower South Platte River basin of Colorado and Nebraska is an area of intense agriculture supported by surface-water diversions from the river and ground-water pumping from a valley-fill alluvial aquifer. Two well networks consisting of 45 wells installed in the South Platte alluvial aquifer were sampled in the early 1990s and again in the early 2000s to examine near-decadal ground-water quality changes in irrigated agricultural areas. Ground-water age generally increases and dissolved-oxygen content decreases with distance along flow paths and with depdi below the water table, and denitrification is an important natural mitigation mechanism for nitrate in downgradient areas. Ground-water travel time from upland areas to the river ranges from 12 to 31 yr on the basis of apparent ground-water ages. Ground-water nitrate concentrations for agricultural land-use wells increased significantly for oxidized samples over the decade, and nitrogen isotope ratios for oxidized samples indicate synthetic fertilizer as the predominant nitrate source. Ground-water concentrations of atrazine, DEA, and prometon decreased significandy. The decrease in pesticide concentrations and a significant increase in the ratio of DEA to atrazine suggest decreases in pesticide concentrations are likely caused by local decreases in application rates and/or degradation processes and that atrazine degradation is promoted by oxidizing conditions. The difference between results for oxidizing and nitrate-reducing conditions indicates redox state is an important variable to consider when evaluating ground-water quality trends for redox-sensitive constituents such as nitrate and pesticides in the South Platte alluvial aquifer. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Geochemistry of ground water in alluvial basins of Arizona and adjacent parts of Nevada, New Mexico, and California

USGS Publications Warehouse

Robertson, Frederick N.

1991-01-01

Chemical and isotope analyses of ground water from 28 basins in the Basin and Range physiographic province of Arizona and parts of adjacent States were used to evaluate ground-water quality, determine processes that control ground-water chemistry, provide independent insight into the hydrologic flow system, and develop information transfer. The area is characterized by north- to northwest-trending mountains separated by alluvial basins that form a regional topography of alternating mountains and valleys. On the basis of ground-water divides or zones of minimal basin interconnection, the area was divided into 72 basins, each representing an individual aquifer system. These systems are joined in a dendritic pattern and collectively constitute the major water resource in the region. Geochemical models were developed to identify reactions and mass transfer responsible for the chemical evolution of the ground water. On the basis of mineralogy and chemistry of the two major rock associations of the area, a felsic model and a mafic model were developed to illustrate geologic, climatic, and physiographic effects on ground-water chemistry. Two distinct hydrochemical processes were identified: (1) reactions of meteoric water with minerals and gases in recharge areas and (2) reactions of ground water as it moves down the hydraulic gradient. Reactions occurring in recharge and downgradient areas can be described by a 13-component system. Major reactions are the dissolution and precipitation of calcite and dolomite, the weathering of feldspars and ferromagnesian minerals, the formation of montmorillonite, iron oxyhydroxides, and probably silica, and, in some basins, ion exchange. The geochemical modeling demonstrated that relatively few phases are required to derive the ground-water chemistry; 14 phases-12 mineral and 2 gas-consistently account for the chemical evolution in each basin. The final phases were selected through analysis of X-ray diffraction and fluorescence data, aqueous speciation and saturation data, and mass-balance and isotopic constraints and through chemical models developed from mineral combinations among the 27 phases that were considered realistic in these geologically and mineralogically complex basins. X-ray diffraction of basin-fill sediments confirm the presence of the postulated minerals and their weathering sequences. High partial pressures of soil CO2 and large concentrations of dissolved CO2 in recharge areas, and the rapid depletion of CO2 downgradient, accompanied by high weathering rates of the silicates which also decrease downgradient, indicate that carbonic acid is the impetus in the weathering process. Reactions in the soil zone and the unsaturated zone are influential and, in some instances, are as important as the mineralogy of the source rock in determining ground-water compositions. The basins can be divided geochemically into two general categories-closed systems, which evolve under closed hydrologic conditions, and open systems, which are open to CO2 and other constituents along the flow path. The ground-water chemistry of the unconfined aquifers in the eastern part of the study area and of the aquifers underlying the flood plain along the Colorado River generally evolves under open conditions. The ground-water chemistry of most basins in the central and western parts and of the confined aquifers in the eastern part evolves under closed conditions. The factors that determine whether a basin is an open or closed system are the amount of and the spatial and seasonal distribution of annual precipitation and the presence or absence of fine-grained confining units. The basins along the Colorado River are unique among basins in the region. Virtually all ground water underlying the flood plain originated as seepage or overbank flow from the Colorado River. Initial deuterium content of about -120 per mil is indicative of precipitation from the central part of Colorado. Using chemical m

Five-year performance monitoring of a high-density polyethylene (HDPE) cover system at a reclaimed mine waste rock pile in the Sydney Coalfield (Nova Scotia, Canada).

PubMed

Power, Christopher; Ramasamy, Murugan; MacAskill, Devin; Shea, Joseph; MacPhee, Joseph; Mayich, David; Baechler, Fred; Mkandawire, Martin

2017-12-01

Cover systems are commonly placed over waste rock piles (WRPs) to limit atmospheric water and oxygen ingress and control the generation and release of acid mine drainage (AMD) to the receiving environment. Although covers containing geomembranes such as high-density polyethylene (HDPE) exhibit the attributes to be highly effective, there are few, if any, published studies monitoring their performance at full-scale WRPs. In 2011, a HDPE cover was installed over the Scotchtown Summit WRP in Nova Scotia, Canada, and extensive field performance monitoring was conducted over the next five years. A range of parameters within the atmosphere, cover, waste rock, groundwater and surface water, were monitored and integrated into a comprehensive hydrogeochemical conceptual model to assess (i) atmospheric ingress to the waste rock, (ii) waste rock acidity and depletion and (iii) evolution of groundwater and surface water quality. Results demonstrate that the cover is effective and meeting site closure objectives. Depletion in oxygen influx resulted in slower sulphide oxidation and AMD generation, while a significant reduction in water influx (i.e. 512 to 50 mm/year) resulted in diminished AMD release. Consistent improvements in groundwater quality (decrease in sulphate and metals; increase in pH) beneath and downgradient of the WRP were observed. Protection and/or significant improvement in surface water quality was evident in all surrounding watercourses due to the improved groundwater plume and elimination of contaminated runoff over previously exposed waste rock. A variably saturated flow and contaminant transport model is currently being developed to predict long-term cover system performance.

Characterization of potential transport pathways and implications for groundwater management near an anticline in the Central Basin area, Los Angeles County, California

USGS Publications Warehouse

Ponti, Daniel J.; Wagner, Brian J.; Land, Michael; Landon, Matthew K.

2014-01-01

The Central Groundwater Basin (Central Basin) of southern Los Angeles County includes ~280 mi2 of the Los Angeles Coastal Plain and serves as the primary source of water for more than two million residents. In the Santa Fe Springs–Whittier–Norwalk area, located in the northeastern part of the basin, several sources of volatile organic compounds have been identified. The volatile organic compunds are thought to have contributed to a large, commingled contaminant plume in groundwater that extends south-southwest downgradient from the Omega Chemical Corporation Superfund Site across folded geologic strata, known as the Santa Fe Springs Anticline. A multifaceted study—that incorporated a three-dimensional sequence-stratigraphic geologic model, two-dimensional groundwater particle-tracking simulations, and new groundwater chemistry data—was conducted to gain insight into the geologic and hydrologic controls on contaminant migration in the study area and to assess the potential for this shallow groundwater contamination to migrate into producing aquifer zones. Conceptual flow models were developed along a flow-parallel cross section based on the modeled stratigraphic architecture, observed geochemistry, and numerical model simulations that generally agree with observed water levels and contaminant distributions. These models predict that contaminants introduced into groundwater at shallow depths near the Omega Chemical Corporation Superfund Site and along the study cross section will likely migrate downgradient to depths intercepted by public supply wells. These conclusions, however, are subject to limitations and simplifications inherent in the modeling approaches used, as well as a significant scarcity of available geologic and hydrogeochemical information at depth and in the downgradient parts of the study area.

Microbiology, Redox and Contaminat Fate in the Grindsted Landfill Leachate Plume - A Summary of 25 Years of work

NASA Astrophysics Data System (ADS)

Christensen, T. H.

2001-05-01

The contamination by leachate of the upper aquifer at the Grindsted Landfill (Denmark) stretches about 300 m downgradient from the landfill. The plume has been described with respect to water chemistry, sediment chemistry, pollutant distribution, microbial counts, PLFA and redox rates determined by unamended bioassays. This presentation summaries the findings and discusses unanswered questions. The landfill was active from 1930 to the mid 1970 and has no engineered leachate collection system. Leachate from municipal as well as from industrial waste has entered the aquifer for more than thirty years. The redox conditions change from strongly anaerobic (methanogenic, sulfate reducing, iron reducing) close to the landfill over manganese reduction and denitrification to aerobic conditions in the outskirts of the plume The redox conditions were determined from groundwater sample composition, hydrogen concentrations and sediment chemistry. The plume showed strong attenuation of aromatic compounds within the first 100 m downgradient of the landfill. Degradation experiments (batch, in-situ testers, long term field injection experiments) could not fully document degradation of all the compounds. MPN-measurements of methanogens, sulfate-reducers, iron-reducers, manganese-reducers and denitrifiers showed abundance of all groups with a slight trend with the redox conditions. PLFA measurements did not provide much insight into the microbial populations of the plume, but confirmed some previous observations. Bioassays gave estimates of the rates of the various redox processes, but showed for some samples more simultaneous redox processes. More than 25 years of work has been put into the Grindsted Landfill leachate plume. References Bjerg, P.L., Rugge, K., Cortsen, J., Nielsen, P.H. & Christensen, T.H. (1999): Degradation of aromatic and chlorinated aliphatic hydrocarbons in the anaerobic part of the Grindsted Landfill leachate plume: In situ microcosm and laboratory batch experiments. Ground Water, 37, 113-121. Bjerg, P.L., Rugge, K., Pedersen, J.K. & Christensen, T.H. (1995): Distribution of redox sensitive groundwater quality parameters downgradient of a landfill (Grindsted, Denmark). Environmental Science and Technology, 29, 1387-1394. Heron, G., Bjerg, P.L., Gravesen, P., Ludvigsen, L. & Christensen, T.H. (1998): Geology and sediment geochemistry of a landfill leachate contaminated aquifer (Grindsted, Denmark). Journal of Contaminant Hydrology, 29, 301-317. Jakobsen, R., Albrechtsen, H.-J., Rasmussen, M., Bay, H., Bjerg, P.L. & Christensen, T.H. (1998): H2 concentrations in a landfill leachate plume (Grindsted, Denmark): In situ energetics of terminal electron acceptor processes. Environmental Science and Technology, 32, 2142-2148. Ludvigsen, L., Albrechtsen, H.-J., Heron, G., Bjerg, P.L. & Christensen, T.H. (1998): Anaerobic microbial redox processes in a landfill leachate contaminated aquifer (Grindsted, Denmark). Journal of Contaminant Hydrology, 33, 273-291. Ludvigsen, L., Albrechtsen, H.-J., Ringelberg, D., Ekelund, F. & Christensen, T.H. (1999): Distribution and composition of microbial populations in a landfill leachate contaminated aquifer (Grindsted, Denmark). Microbial Ecology, 37, (3), 197-207. Rugge, K., Bjerg, P.L. & Christensen, T.H. (1995): Distribution of organic compounds from municipal solid waste in the groundwater downgradient of a landfill (Grindsted, Denmark). Environmental Science and Technology, 29, 1395-1400.

Connecting the Dots: Hydrologic Connectivity Between ...

EPA Pesticide Factsheets

Wetlands perform numerous ecosystem functions that in turn provide abundant ecosystem services beneficial to humankind. These may include, but are not limited to, flood water storage and release, nutrient transformations, carbon sequestration, and the provision of habitat or refugia. The importance of wetland effects on downgradient waters, such as other wetlands or streams, lies in the degree to which they are hydrologically connected or disconnected across the landscape. Featured article on the emerging science of aquatic system connectivity.

CARBON-BASED REACTIVE BARRIER FOR NITRATE ...

EPA Pesticide Factsheets

Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constructed for in-situ bioremediation of a ground water nitrate plume caused by leakage from a swine CAFO (concentrated animal feeding operation) lagoon. The swine CAFO, located in Logan County, Oklahoma, was in operation from 1992-1999. The overall site remediation strategy includes an ammonia recovery trench to intercept ammonia-contaminated ground water and a hay straw PRB which is used to intercept a nitrate plume caused by nitrification of sorbed ammonia. The PRB extends approximately 260 m to intercept the nitrate plume. The depth of the trench averages 6 m and corresponds to the thickness of the surficial saturated zone; the width of the trench is 1.2 m. Detailed quarterly monitoring of the PRB began in March, 2004, about 1 year after construction activities ended. Nitrate concentrations hydraulically upgradient of the PRB have ranged from 23 to 77 mg/L N, from 0 to 3.2 mg/L N in the PRB, and from 0 to 65 mg/L N hydraulically downgradient of the PRB. Nitrate concentrations have generally decreased in downgradient locations with successive monitoring events. Mass balance considerations indicate that nitrate attenuation is dominantly from denitrification but with some component of

Geochemical and Hydrologic Factors Controlling Subsurface Transport of Poly- and Perfluoroalkyl Substances, Cape Cod, Massachusetts.

PubMed

Weber, Andrea K; Barber, Larry B; LeBlanc, Denis R; Sunderland, Elsie M; Vecitis, Chad D

2017-04-18

Growing evidence that certain poly- and perfluoroalkyl substances (PFASs) are associated with negative human health effects prompted the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in 2016. Given that groundwater is a major source of drinking water, the main objective of this work was to investigate geochemical and hydrological processes governing the subsurface transport of PFASs at a former fire training area (FTA) on Cape Cod, Massachusetts, where PFAS-containing aqueous film-forming foams were used historically. A total of 148 groundwater samples and 4 sediment cores were collected along a 1200-m-long downgradient transect originating near the FTA and analyzed for PFAS content. The results indicate that unsaturated zones at the FTA and at hydraulically downgradient former domestic wastewater effluent infiltration beds both act as continuous PFAS sources to the groundwater despite 18 and 20 years of inactivity, respectively. Historically different PFAS sources are evident from contrasting PFAS composition near the water table below the FTA and wastewater-infiltration beds. Results from total oxidizable precursor assays conducted using groundwater samples collected throughout the plume suggest that some perfluoroalkyl acid precursors at this site are transporting with perfluoroalkyl acids.

Geochemical and hydrologic factors controlling subsurface transport of poly- and perfluoroalkyl substances, Cape Cod, Massachusetts

USGS Publications Warehouse

Weber, Andrea K.; Barber, Larry B.; LeBlanc, Denis R.; Sunderland, Elsie M.; Vecitis, Chad D.

2017-01-01

Growing evidence that certain poly- and perfluoroalkyl substances (PFASs) are associated with negative human health effects prompted the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in 2016. Given that groundwater is a major source of drinking water, the main objective of this work was to investigate geochemical and hydrological processes governing the subsurface transport of PFASs at a former fire training area (FTA) on Cape Cod, Massachusetts, where PFAS-containing aqueous film-forming foams were used historically. A total of 148 groundwater samples and 4 sediment cores were collected along a 1200-m-long downgradient transect originating near the FTA and analyzed for PFAS content. The results indicate that unsaturated zones at the FTA and at hydraulically downgradient former domestic wastewater effluent infiltration beds both act as continuous PFAS sources to the groundwater despite 18 and 20 years of inactivity, respectively. Historically different PFAS sources are evident from contrasting PFAS composition near the water table below the FTA and wastewater-infiltration beds. Results from total oxidizable precursor assays conducted using groundwater samples collected throughout the plume suggest that some perfluoroalkyl acid precursors at this site are transporting with perfluoroalkyl acids.

Data Validation Package October 2015 Groundwater and Surface Water Sampling at the Monticello, Utah, Processing Site January 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Jason; Smith, Fred

Sampling Period: October 12–14, 2015. This semiannual event includes sampling groundwater and surface water at the Monticello Mill Tailings Site. Sampling and analyses were conducted as specified in the 2004 Monticello Mill Tailings Site Operable Unit III Post-Record of Decision Monitoring Plan, Draft Final and Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated). Samples were collected from 52 of 61 planned locations (15 of 17 former mill site wells, 17 of 18 downgradient wells, 9 of 9 downgradient permeable reactive barrier wells, 2 of 7 seeps and wetlands, and 9 ofmore » 10 surface water locations). Locations MW00-07, Seep 1, Seep 2, Seep 3, Seep 5, Seep 6, SW00-01, T01-13, and T01-19 were not sampled because of insufficient water availability. All samples were filtered as specified in the monitoring plan. Duplicate samples were collected from surface water location W3-04 and from monitoring wells 82-08, 92-09, and 92-10. Water levels were measured at all but one sampled well and an additional set of wells. The contaminants of concern (COCs) for the Monticello Mill Tailings Site are arsenic, manganese, molybdenum, nitrate + nitrite as nitrogen (nitrate + nitrite as N), selenium, uranium, and vanadium. Time-concentration graphs of the COCs for all groundwater and surface water locations are included in this report. Locations with COCs that exceeded remediation goals are listed.« less

Extent and persistence of secondary water quality impacts after enhanced reductive bioremediation

USGS Publications Warehouse

Borden, Robert C.; Jason M. Tillotson,; Ng, Gene-Hua Crystal.; Bekins, Barbara A.; Kent, Douglas B.; Curtis, Gary P.

2017-01-01

Electron donor (ED) addition can be very effective in stimulating enhanced reductive bioremediation (ERB) of a wide variety of groundwater contaminants. However, ERB can result in Secondary Water Quality Impacts (SWQIs) including decreased levels of dissolved oxygen (O2), nitrate (NO3- ), and sulfate (SO42- ), and elevated levels of dissolved manganese (Mn2+), dissolved iron (Fe2+), methane (CH4), sulfide (S2- ), organic carbon, and naturally occurring hazardous compounds (e.g., arsenic). Fortunately, this ‘plume’ of impacted groundwater is usually confined within the original contaminant plume and is unlikely to adversely impact potable water supplies. This report summarizes available information on processes controlling the production and natural attenuation of SWQI parameters and can be used as a guide in understanding the magnitude, areal extent, and duration of SWQIs in ERB treatment zones and the natural attenuation of SWQI parameters as the dissolved solutes migrate downgradient with ambient groundwater flow. This information was compiled from a wide variety of sources including a survey and statistical analysis of SWQIs from 47 ERB sites, geochemical model simulations, field studies at sites where organic-rich materials have entered the subsurface (e.g., wastewater, landfill leachate, and hydrocarbon plumes), and basic information on physical, chemical, and biological processes in the subsurface. This information is then integrated to provide a general conceptual model of the major processes controlling SWQI production and attenuation.

Enhanced bioremediation of BTEX using immobilized nutrients: Field demonstration and monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borden, R.C.; Goin, R.T.; Kao, C.M.

1996-12-01

A permeable barrier system was developed for controlling the migration of dissolved contaminant plumes in ground water. The barrier system consisted of a line of closely spaced wells installed perpendicular to the contaminant plume. Each well contained concrete briquets that released oxygen and nitrate at a controlled rate, enhancing the aerobic biodegradation of dissolved hydrocarbons in the downgradient aquifer. A full scale permeable barrier system was constructed at a gasoline-spill site near Leland, NC. Initially, increased dissolved oxygen and decreased benzene, toluene, ethylbenzene, and xylene isomer (BTEX) concentrations in the downgradient aquifer indicated that oxygen released from the remediation wellsmore » was enhancing biodegradation. Field tracer tests and soil analyses performed at the conclusion of the project indicated that the aquifer in the vicinity of the remediation wells was being clogged by precipitation from iron minerals.« less

The combined use of 87Sr/86Sr and carbon and water isotopes to study the hydrochemical interaction between groundwater and lakewater in mantled karst

USGS Publications Warehouse

Katz, B.G.; Bullen, T.D.

1996-01-01

The hydrochemical interaction between groundwater and lakewater influences the composition of water that percolates downward from the surficial aquifer system through the underlying intermediate confining unit and recharges the Upper Floridan aquifer along highlands in Florida. The 87Sr/86Sr ratio along with the stable isotopes, D, 18O, and 13C were used as tracers to study the interaction between groundwater, lakewater, and aquifer minerals near Lake Barco, a seepage lake in the mantled karst terrane of northern Florida. Upgradient from the lake, the 87Sr/86Sr ratio of groundwater decreases with depth (mean values of 0.71004, 0.70890, and 0.70852 for water from the surficial aquifer system, intermediate confining unit, and Upper Floridan aquifer, respectively), resulting from the interaction of dilute oxygenated recharge water with aquifer minerals that are less radiogenic with depth. The concentrations of Sr2+ generally increase with depth, and higher concentrations of Sr2+ in water from the Upper Floridan aquifer (20-35 ??g/L), relative to water from the surficial aquifer system and the intermediate confining unit, result from the dissolution of Sr-bearing calcite and dolomite in the Eocene limestone. Dissolution of calcite [??13C = -1.6 permil (???)] is also indicated by an enriched ??13CDIC (-8.8 to - 11.4???) in water from the Upper Floridan aquifer, relative to the overlying hydrogeologic units (??13CDIC < - 16???). Groundwater downgradient from Lake Barco was enriched in 18O and D relative to groundwater upgradient from the lake, indicating mixing of lakewater leakage and groundwater. Downgradient from the lake, the 87Sr/86Sr ratio of groundwater and aquifer material become less radiogenic and the Sr2+ concentrations generally increase with depth. However, Sr2+ concentrations are substantially less than in upgradient groundwaters at similar depths. The lower Sr2+ concentrations result from the influence of anoxic lakewater leakage on the mobility of Sr2+ from clays. Based on results from mass-balance modeling, it is probable that cation exchange plays the dominant role in controlling the 87Sr/86Sr ratio of groundwater, both upgradient and downgradient from Lake Barco. Even though groundwater from the three distinct hydrogeologic units displays considerable variability in Sr concentration and isotopic composition, the dominant processes associated with the mixing of lakewater leakage with groundwater, as well as the effects of mineral-water interaction, can be ascertained by integrating the use of stable and radiogenic isotopic measurements of groundwater, lakewater, and aquifer minerals.

Radiocarbon dating of dissolved inorganic carbon in groundwater from confined parts of the Upper Floridan aquifer, Florida, USA

USGS Publications Warehouse

Plummer, Niel; Sprinkle, C.L.

2001-01-01

Geochemical reaction models were evaluated to improve radiocarbon dating of dissolved inorganic carbon (DIC) in groundwater from confined parts of the Upper Floridan aquifer in central and northeastern Florida, USA. The predominant geochemical reactions affecting the 14C activity of DIC include (1) dissolution of dolomite and anhydrite with calcite precipitation (dedolomitization), (2) sulfate reduction accompanying microbial degradation of organic carbon, (3) recrystallization of calcite (isotopic exchange), and (4) mixing of fresh water with as much as 7% saline water in some coastal areas. The calculated cumulative net mineral transfers are negligibly small in upgradient parts of the aquifer and increase significantly in downgradient parts of the aquifer, reflecting, at least in part, upward leakage from the Lower Floridan aquifer and circulation that contacted middle confining units in the Floridan aquifer system. The adjusted radiocarbon ages are independent of flow path and represent travel times of water from the recharge area to the sample point in the aquifer. Downgradient from Polk City (adjusted age 1.7 ka) and Keystone Heights (adjusted age 0.4 ka), 14 of the 22 waters have adjusted 14C ages of 20-30 ka, indicating that most of the fresh-water resource in the Upper Floridan aquifer today was recharged during the last glacial period. All of the paleowaters are enriched in 18O and 2H relative to modern infiltration, with maximum enrichment in ??18O of approximately 2.0%o.

Organic Wastewater Compounds, Pharmaceuticals, andColiphage in Ground Water Receiving Discharge from OnsiteWastewater Treatment Systems near La Pine, Oregon:Occurrence and Implications for Transport

USGS Publications Warehouse

Hinkle, Stephen J.; Weick, Rodney J.; Johnson, Jill M.; Cahill, Jeffery D.; Smith, Steven G.; Rich, Barbara J.

2005-01-01

The occurrence of organic wastewater compounds (components of 'personal care products' and other common household chemicals), pharmaceuticals (human prescription and nonprescription medical drugs), and coliphage (viruses that infect coliform bacteria, and found in high concentrations in municipal wastewater) in onsite wastewater (septic tank effluent) and in a shallow, unconfined, sandy aquifer that serves as the primary source of drinking water for most residents near La Pine, Oregon, was documented. Samples from two types of observation networks provided basic occurrence data for onsite wastewater and downgradient ground water. One observation network was a group of 28 traditional and innovative (advanced treatment) onsite wastewater treatment systems and associated downgradient drainfield monitoring wells, referred to as the 'innovative systems network'. The drainfield monitoring wells were located adjacent to or under onsite wastewater treatment system drainfield lines. Another observation network, termed the 'transect network', consisted of 31 wells distributed among three transects of temporary, stainless-steel-screened, direct-push monitoring wells installed along three plumes of onsite wastewater. The transect network, by virtue of its design, also provided a basis for increased understanding of the transport of analytes in natural systems. Coliphage were frequently detected in onsite wastewater. Coliphage concentrations in onsite wastewater were highly variable, ranging from less than 1 to 3,000,000 plaque forming units per 100 milliliters. Coliphage were occasionally detected (eight occurrences) at low concentrations in samples from wells located downgradient from onsite wastewater treatment system drainfield lines. However, coliphage concentrations were below method detection limits in replicate or repeat samples collected from the eight sites. The consistent absence of coliphage detections in the replicate or repeat samples is interpreted to indicate that the detections reported for ground-water samples represented low-level field or laboratory contamination, and it would appear that coliphage were effectively attenuated to less than 1 PFU/100 mL over distances of several feet of transport in the La Pine aquifer and (or) overlying unsaturated zone. Organic wastewater compounds were frequently detected in onsite wastewater. Of the 63 organic wastewater compounds in the analytical schedule, 45 were detected in the 21 samples of onsite wastewater. Concentrations of organic wastewater compounds reached a maximum of 1,300 ug/L (p-cresol). Caffeine was detected at concentrations as high as 320 ug/L. Fourteen of the 45 compounds were detected in more than 90 percent of onsite wastewater samples. Fewer (nine) organic wastewater compounds were detected in ground water, despite the presence of nitrate and chloride likely from onsite wastewater sources. The nine organic wastewater compounds that were detected in ground-water samples were acetyl-hexamethyl-tetrahydro-naphthalene (AHTN), caffeine, cholesterol, hexahydrohexamethyl-cyclopentabenzopyran, N,N-diethyl-meta-toluamide (DEET), tetrachloroethene, tris (2-chloroethyl) phosphate, tris (dichloroisopropyl) phosphate, and tributyl phosphate. Frequent detection of household-chemical type organic wastewater compounds in onsite wastewater provides evidence that some of these organic wastewater compounds may be useful indicators of human waste effluent dispersal in some hydrologic environments. The occurrence of organic wastewater compounds in ground water downgradient from onsite wastewater treatment systems demonstrates that a subgroup of organic wastewater compounds is transported in the La Pine aquifer. The consistently low concentrations (generally less than 1 ug/L) of organic wastewater compounds in water samples collected from wells located no more than 19 feet from drainfield lines indicates that the reactivity (sorption, degradation) of this suite of organic waste

Hydrogeology and trichloroethene contamination in the sea-level aquifer beneath the Logistics Center, Fort Lewis, Washington

USGS Publications Warehouse

Dinicola, Richard S.

2005-01-01

The U.S. Army disposed of waste trichloroethene (TCE) and other materials in the East Gate Disposal Yard near the Logistics Center on Fort Lewis, Washington, from the 1940s to the early 1970s. As a result, ground water contaminated with primarily TCE extends more than 3 miles downgradient from the East Gate Disposal Yard. The site is underlain by a complex and heterogeneous sequence of glacial and non-glacial deposits that have been broadly categorized into an upper and a lower aquifer (the latter referred to as the sea-level aquifer). TCE contamination was detected in both aquifers. This report describes an investigation by the U.S. Geological Survey (USGS) of the source, migration, and attenuation of TCE in the sea-level aquifer. A refined conceptual model for ground-water flow and contaminant migration into and through the sea-level aquifer was developed in large part from interpretation of environmental tracer data. The tracers used included stable isotopes of oxygen (18O), hydrogen (2H), and carbon (13C); the radioactive hydrogen isotope tritium (3H); common ions and redox-related analytes; chlorofluorocarbons; and sulfur hexafluoride. Tracer and TCE concentrations were determined for samples collected by the USGS from 37 wells and two surface-water sites in American Lake during 1999-2000. Ground-water levels were measured by the USGS in more than 40 wells during 2000-01, and were combined with measurements by the U.S. Army and others to create potentiometric-surface maps. Localized ground-water flow features were identified that are of particular relevance to the migration of TCE in the study area. A ridge of ground water beneath American Lake diverts the flow of TCE-contaminated ground water in the sea-level aquifer to the west around the southern end of the lake. Tracer data provided clear evidence that American Lake is a significant source of recharge to the sea-level aquifer that has created that ridge of ground water. High ground-water altitudes at locations north and northeast of the Logistics Center combined with the ridge beneath American Lake prevent TCE contaminated water beneath the Logistics Center from migrating toward municipal water-supply wells northeast of the site. The 1999-2000 TCE concentrations measured by the USGS at older wells screened in the sea-level aquifer were similar to those measured since 1995, but the known downgradient extent of the TCE contamination expanded nearly 2 miles after the Army installed and sampled new wells during 2003-04. Concentrations of TCE in the sea-level aquifer were consistently highest in the upper part of the aquifer throughout the plume, although TCE has spread throughout much of the thickness of the aquifer in the downgradient portions of the plume. Environmental tracer data indicated that the primary pathway for contaminant migration into the sea-level aquifer is through the previously identified confining unit window, an area where the predominately fine-grained confining unit is relatively coarse grained and more permeable. Other less substantial pathways for contaminant migration also were identified near the East Gate Disposal Yard and the I-5 pump-and-treat facilities. Those areas are near active pumping wells and ground-water reintroduction facilities, but there is no evidence that the contaminant migration was caused or enhanced by those activities. Within the sea-level aquifer, TCE concentrations continue to migrate westward in the flow field strongly influenced by ground-water recharge from American Lake. Historical data are not available to definitively determine if the 5-?g/L leading edge of the current TCE plume is stable or if it is still moving downgradient. However, an evaluation of the available data combined with TCE traveltime estimates indicates that the peak TCE concentrations in the sea-level aquifer may have not yet reached the wells near the currently defined leading edge of the plume. Hypothetically, the 5-?g/L leading edge

Data Validation Package April 2016 Groundwater and Surface Water Sampling at the Monticello, Utah, Disposal and Processing Sites August 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Jason; Smith, Fred

This semiannual event includes sampling groundwater and surface water at the Monticello Disposal and Processing Sites. Sampling and analyses were conducted as specified in the Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated) and Program Directive MNT-2016-01. Complete sample sets were collected from 42 of 48 planned locations (9 of 9 former mill site wells, 13 of 13 downgradient wells, 7 of 9 downgradient permeable reactive barrier wells, 4 of 7 seeps and wetlands, and 9 of 10 surface water locations). Planned monitoring locations are shown in Attachment 1, Sampling andmore » Analysis Work Order. Locations R6-M3, SW00-01, Seep 1, Seep 2, and Seep 5 were not sampled due to insufficient water availability. A partial sample was collected at location R4-M3 due to insufficient water. All samples from the permeable reactive barrier wells were filtered as specified in the program directive. Duplicate samples were collected from surface water location Sorenson and from monitoring wells 92-07 and RlO-Ml. Water levels were measured at all sampled wells and an additional set of wells. See Attachment2, Trip Report for additional details. The contaminants of concern (COCs) for the Monticello sites are arsenic, manganese, molybdenum, nitrate+ nitrite as nitrogen (nitrate+ nitrite as N), selenium, uranium, and vanadium. Locations with COCs that exceeded remediation goals are listed in Table 1 and Table 2. Time-concentration graphs of the COCs for all groundwater and surface water locations are included in Attachment 3, Data Presentation. An assessment of anomalous data is included in Attachment 4.« less

Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 1. Flow Patterns, Age of Groundwater, and Influence of Lake Water Leakage

NASA Astrophysics Data System (ADS)

Katz, Brian G.; Lee, Terrie M.; Plummer, L. Niel; Busenberg, Eurybiades

1995-06-01

Leakage from sinkhole lakes significantly influences recharge to the Upper Floridan aquifer in poorly confined sediments in northern Florida. Environmental isotopes (oxygen 18, deuterium, and tritium), chlorofluorocarbons (CFCs: CFC-11, CCl3F; CFC-12, CCl2F2; and CFC-113, C2Cl3F3), and solute tracers were used to investigate groundwater flow patterns near Lake Barco, a seepage lake in a mantled karst setting in northern Florida. Stable isotope data indicated that the groundwater downgradient from the lake contained 11-67% lake water leakage, with a limit of detection of lake water in groundwater of 4.3%. The mixing fractions of lake water leakage, which passed through organic-rich sediments in the lake bottom, were directly proportional to the observed methane concentrations and increased with depth in the groundwater flow system. In aerobic groundwater upgradient from Lake Barco, CFC-modeled recharge dates ranged from 1987 near the water table to the mid 1970s for water collected at a depth of 30 m below the water table. CFC-modeled recharge dates (based on CFC-12) for anaerobic groundwater downgradient from the lake ranged from the late 1950s to the mid 1970s and were consistent with tritium data. CFC-modeled recharge dates based on CFC-11 indicated preferential microbial degradation in anoxic waters. Vertical hydraulic conductivities, calculated using CFC-12 modeled recharge dates and Darcy's law, were 0.17, 0.033, and 0.019 m/d for the surficial aquifer, intermediate confining unit, and lake sediments, respectively. These conductivities agreed closely with those used in the calibration of a three-dimensional groundwater flow model for transient and steady state flow conditions.

Groundwater quality assessment/corrective action feasibility plan: New TNX Seepage Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nichols, R.L.

1989-12-05

The New TNX Seepage Basin is located across River Road east of the TNX Area at the Savannah River Site. Currently the basin is out of service and is awaiting closure in accordance with the Consent Decree settled under Civil Act No. 1:85-2583. Groundwater monitoring data from the detection monitoring network around the New TNX Seepage Basin was recently analyzed using South Carolina Hazardous Waste Management Regulations R.61-79.264.92 methods to determine if groundwater downgradient of the New TNX Seepage Basin had been impacted. Results from the data analysis indicate that the groundwater has been impacted by inorganic constituents with nomore » associated health risks. The impacts resulting from elevated levels of inorganic constituents, such as Mn, Na, and Total PO{sub 4} in the water table, do not pose a threat to human health and the environment.« less

Evaluation of a predictive ground-water solute-transport model at the Idaho National Engineering Laboratory, Idaho

USGS Publications Warehouse

Lewis, Barney D.; Goldstein, Flora J.

1982-01-01

Aqueous chemical and radioactive wastes discharged to shallow ponds and to shallow or deep wells on the Idaho National Engineering Laboratory (INEL) since 1952 have affected the quality of the ground water in the underlying Snake River Plain aquifer. The aqueous wastes have created large and laterally dispersed concentration plumes within the aquifer. The waste plumes with the largest areal distribution are those of chloride , tritium, and with high specific conductance values. The data from eight wells drilled near the southern INEL boundary during the summer of 1980 were used to evaluate the accuracy of a predictive modeling study completed in 1973, and to simulate 1980 positions of chloride and tritium plumes. Data interpretation from the drilling program indicates that the hydrogeologic characteristics of the subsurface rocks have marked effects on the regional ground-water flow regimen and, therefore, the movement of aqueous wastes. As expected, the waste plumes projected by the computer model for 1980, extended somewhat further downgradient than indicated by well data due to conservative worst-case assumptions in the model input and inacurate approximations of subsequent waste discharge and aquifer recharge conditions. (USGS)

Onsite Wastewater System Nitrogen Contributions to Groundwater in Coastal North Carolina

PubMed Central

Humphrey, C.P.; O’Driscoll, M.A.; Deal, N.E.; Lindbo, D.L.; Thieme, S.C.; Zarate-Bermudez, M.A.

2016-01-01

The objective of the study described in this article was to evaluate the nitrogen contributions from two onsite wastewater systems (sites 1 and 2) to groundwater and adjacent surface waters in coastal Beaufort County, North Carolina. Groundwater levels and water quality parameters including total nitrogen, nitrogen species, temperature, and pH were monitored from October 2009 to May 2010. Nitrogen was also tested in groundwater from deeper irrigation or drinking water wells from the two sites and six additional neighboring residences. Mean total nitrogen concentrations in groundwater beneath onsite wastewater systems 1 and 2 were 34.3 ± 16.7 mg/L and 12.2 ± 2.9 mg/L, respectively, and significantly higher than background groundwater concentrations (<1 mg/L). Groundwater in the deeper wells appeared not to be influenced by the onsite systems. Groundwater nitrogen concentrations typically decreased with distance down-gradient from the systems, but were still elevated relative to background conditions more than 15 m from the systems and near the estuary. This was a pioneering effort to better understand the link of onsite systems, the fate of nitrogen in the environment, and public health. PMID:24437045

Evaluation of the fate and transport of chlorinated ethenes in a complex groundwater system discharging to a stream in Wonju, Korea.

PubMed

Lee, Seong-Sun; Kaown, Dugin; Lee, Kang-Kun

2015-11-01

Chlorinated ethenes such as trichloroethylene (TCE) are common and persistent groundwater contaminants. If contaminated groundwater discharges to a stream, then stream water pollution near the contamination site also becomes a problem. In this respect, the fate and transport of chlorinated ethenes around a stream in an industrial complex were evaluated using the concentration of each component, and hydrogeochemical, microbial, and compound-specific carbon isotope data. Temporal and spatial monitoring reveal that a TCE plume originating from main and local source zones continues to be discharged to a stream. Groundwater geochemical data indicate that aerobic conditions prevail in the upgradient area of the studied aquifer, whereas conditions become anaerobic in the downgradient. The TCE molar fraction is high at the main and local source zones, ranging from 87.4 to 99.2% of the total volatile organic compounds (VOCs). An increasing trend in the molar fraction of cis-1, 2-Dichloroethene (cis-DCE) and vinyl chloride (VC) was observed in the downgradient zone of the study area. The enriched δ(13)C values of TCE and depleted values of cis-DCE in the stream zone, compared to those of the source zone, also suggest biodegradation of VOCs. Microbial community structures in monitoring wells adjacent to the stream zone in the downgradient area were analyzed using 16S rRNA gene-based pyrosequencing to identify the microorganisms responsible for biodegradation. This was attributed to the high relative abundance of dechlorinating bacteria in monitoring wells under anaerobic conditions farthest from the stream in the downgradient area. The multilateral approaches adopted in this study, combining hydrogeochemical and biomolecular methods with compound-specific analyses, indicate that contaminants around the stream were naturally attenuated by active anaerobic biotransformation processes. Copyright © 2015 Elsevier B.V. All rights reserved.

Data Validation Package May 2016 Groundwater Sampling at the Sherwood, Washington, Disposal Site August 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreie, Ken; Traub, David

The 2001 Long-Term Surveillance Plan (LTSP) for the US. Department of Energy Sherwood Project (UMI'RCA Title II) Reclamation Cell, Wellpinit, Washington, does not require groundwater compliance monitoring at the Sherwood site. However, the LTSP stipulates limited groundwater monitoring for chloride and sulfate (designated indicator parameters) and total dissolved solids (TDS) as a best management practice. Samples were collected from the background well, MW-2B, and the two downgradient wells, MW-4 and MW-10, in accordance with the LTSP. Sampling and analyses were conducted as specified in the Sampling and Analysis Plan for US. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351,more » continually updated). Water levels were measured in all wells prior to sampling and in four piezometers completed in the tailings dam. Time-concentration graphs included in this report indicate that the chloride, sulfate, and TDS concentrations are consistent with historical measurements. The concentrations of chloride and sulfate are well below the State of Washington water quality criteria value of 250 milligrams per liter (mg/L) for both parameters.« less

Comparison of chemical hydrogeology of the carbonate peninsulas of Florida and Yucatan

USGS Publications Warehouse

Back, W.; Hanshaw, B.B.

1970-01-01

Aquifers of the peninsulas of Florida and northern Yucatan are Tertiary marine carbonate formations showing many lithologic and faunal similarities. In addition, the tropical to subtropical climates of the two areas are similar, each having annual rainfall of about 1000 to 1500 mm. Despite similarities in these fundamental controls, contrasts in the hydrologic and geochemical systems are numerous and striking. For example, Florida has many rivers; Yucatan has none. Maximum thickness of fresh ground water in Florida is about 700 meters; in the Yucatan it is less than 70 meters. In Florida the gradient of the potentiometric surface averages about 1 meter per kilometer; in the Yucatan it is exceedingly low, averaging about 0.02 meter per kilometer. In Florida the chemical character of water changes systematically downgradient, owing to solution of minerals of the aquifer and corresponding increases in total dissolved solids, sulfate, calcium, and Mg-Ca ratio; in the Yucatan no downgradient change exists, and dominant processes controlling the chemical character of the water are solution of minerals and simple mixing of the fresh water and the body of salt water that underlies the peninsula at shallow depth. Hydrologic and chemical differences are caused in part by the lower altitude of the Yucatan plain. More important, however, these differences are due to the lack of an upper confining bed in Yucatan that is hydrologically equivalent to the Hawthorn Formation of Florida. The Hawthorn cover prevents recharge and confines the artesian water except where it is punctured by sinkholes, but sands and other unconsolidated sediments fill sinkholes and cavities and impede circulation. In the Yucatan the permeability of the entire section is so enormous that rainfall immediately infiltrates to the water table and then moves laterally to discharge areas along the coasts. ?? 1970.

Chemical evolution of groundwater near a sinkhole lake, northern Florida: 1. Flow patterns, age of groundwater, and influence of lakewater leakage

USGS Publications Warehouse

Katz, Brian G.; Lee, Terrie M.; Plummer, Niel; Busenberg, Eurybiades

1995-01-01

Leakage from sinkhole lakes significantly influences recharge to the Upper Floridan aquifer in poorly confined sediments in northern Florida. Environmental isotopes (oxygen 18, deuterium, and tritium), chlorofluorocarbons (CFCs: CFC-11, CCl3F; CFC-12, CCl2F2; and CFC-113, C2Cl3F3), and solute tracers were used to investigate groundwater flow patterns near Lake Barco, a seepage lake in a mantled karst setting in northern Florida. Stable isotope data indicated that the groundwater downgradient from the lake contained 11–67% lake water leakage, with a limit of detection of lake water in groundwater of 4.3%. The mixing fractions of lake water leakage, which passed through organic-rich sediments in the lake bottom, were directly proportional to the observed methane concentrations and increased with depth in the groundwater flow system. In aerobic groundwater upgradient from Lake Barco, CFC-modeled recharge dates ranged from 1987 near the water table to the mid 1970s for water collected at a depth of 30 m below the water table. CFC-modeled recharge dates (based on CFC-12) for anaerobic groundwater downgradient from the lake ranged from the late 1950s to the mid 1970s and were consistent with tritium data. CFC-modeled recharge dates based on CFC-11 indicated preferential microbial degradation in anoxic waters. Vertical hydraulic conductivities, calculated using CFC-12 modeled recharge dates and Darcy's law, were 0.17, 0.033, and 0.019 m/d for the surficial aquifer, intermediate confining unit, and lake sediments, respectively. These conductivities agreed closely with those used in the calibration of a three-dimensional groundwater flow model for transient and steady state flow conditions.

Evaluation of volatilization as a natural attenuation pathway for MTBE

USGS Publications Warehouse

Lahvis, Matthew A.; Baehr, Arthur L.; Baker, Ronald J.

2004-01-01

Volatilization and diffusion through the unsaturated zone can be an important pathway for natural attenuation remediation of methyl tert-butyl ether (MTBE) at gasoline spill sites. The significance of this pathway depends primarily on the distribution of immiscible product within the unsaturated zone and the relative magnitude of aqueous-phase advection (ground water recharge) to gaseous-phase diffusion. At a gasoline spill site in Laurel Bay, South Carolina, rates of MTBE volatilization from ground water downgradient from the source are estimated by analyzing the distribution of MTBE in the unsaturated zone above a solute plume. Volatilization rates of MTBE from ground water determined by transport modeling ranged from 0.0020 to 0.0042 g m-2/year, depending on the assumed rate of ground water recharge. Although diffusive conditions at the Laurel Bay site are favorable for volatilization, mass loss of MTBE is insignificant over the length (230 m) of the solute plume. Based on this analysis, significant volatilization of MTBE from ground water downgradient from source areas at other sites is not likely. In contrast, model results indicate that volatilization coupled with diffusion to the atmosphere could be a significant mass loss pathway for MTBE in source areas where residual product resides above the capillary zone. Although not documented, mass loss of MTBE at the Laurel Bay site due to volatilization and diffusion to the atmosphere are predicted to be two to three times greater than mass loading of MTBE to ground water due to dissolution and recharge. This result would imply that volatilization in the source zone may be the critical natural attenuation pathway for MTBE at gasoline spill sites, especially when considering capillary zone limitations on volatilization of MTBE from ground water and the relative recalcitrance of MTBE to biodegradation.

Hydrogeology and water quality of the West Valley Creek Basin, Chester County, Pennsylvania

USGS Publications Warehouse

Senior, Lisa A.; Sloto, Ronald A.; Reif, Andrew G.

1997-01-01

The West Valley Creek Basin drains 20.9 square miles in the Piedmont Physiographic Province of southeastern Pennsylvania and is partly underlain by carbonate rocks that are highly productive aquifers. The basin is undergoing rapid urbanization that includes changes in land use and increases in demand for public water supply and wastewater disposal. Ground water is the sole source of supply in the basin.West Valley Creek flows southwest in a 1.5-mile-wide valley that is underlain by folded and faulted carbonate rocks and trends east-northeast, parallel to regional geologic structures. The valley is flanked by hills underlain by quartzite and gneiss to the north and by phyllite and schist to the south. Surface water and ground water flow from the hills toward the center of the valley. Ground water in the valley flows west-southwest parallel to the course of the stream. Seepage investigations identified losing reaches in the headwaters area where streams are underlain by carbonate rocks and gaining reaches downstream. Tributaries contribute about 75 percent of streamflow. The ground-water and surface-water divides do not coincide in the carbonate valley. The ground-water divide is about 0.5 miles west of the surface-water divide at the eastern edge of the carbonate valley. Underflow to the east is about 1.1 inches per year. Quarry dewatering operations at the western edge of the valley may act partly as an artificial basin boundary, preventing underflow to the west. Water budgets for 1990, a year of normal precipitation (45.8 inches), and 1991, a year of sub-normal precipitation (41.5 inches), were calculated. Streamflow was 14.61 inches in 1990 and 12.08 inches in 1991. Evapotranspiration was estimated to range from 50 to 60 percent of precipitation. Base flow was about 62 percent of streamflow in both years. Exportation by sewer systems was about 3 inches from the basin and, at times, equaled base flow during the dry autumn of 1991. Recharge was estimated to be 18.5 inches in 1990 and 13.7 inches in 1991. Ground-water quality in the basin reflects differences in lithology and has been affected by human activities. Ground water in the carbonate rocks is naturally hard, has a near neutral pH, and contains more dissolved solids and less dissolved iron, manganese, and radon-222 than ground water in the noncarbonate rocks, which is soft, with moderately acidic to acidic pH. Regional contamination by chloride and nitrate and local contamination by organic compounds and metals was detected. Natural background concentrations are estimated to be about 1 milligram per liter for nitrate as nitrogen and less than 3 milligrams per liter for chloride. Ground water in unsewered areas and agricultural areas of the basin has median concentrations of nitrate that are greater than those in ground water from other areas; septic system effluent and fertilizer are probable sources of elevated nitrate. Water samples from wells in urbanized areas contain greater concentrations of chloride than samples from wells in residential areas; road salt is the probable source of elevated chloride. Organic solvents, especially trichloroethylene, were detected in 30 percent of the wells sampled in the urbanized carbonate valley. Most of the organic solvents and some of the metals in ground water were detected near old industrial sites.Base-flow stream quality of West Valley Creek was determined at 15 sites from monthly sampling for 1 year. Differences in stream quality reflect differences in lithology, land use, and point sources in tributary subbasins and mainstem reaches. The chemical composition of base flow in the mainstem is dominated by ground-water discharge from carbonate rocks. Elevated concentrations of nitrate (greater than 3 milligrams per liter as nitrogen) in base flow were measured in a tributary draining agricultural land and in a tributary draining an unsewered residential area. Elevated concentrations of phosphate (greater than 0.5 milligrams per liter as phosphorus) were measured in a stream that receives treated sewage effluent. Discharge of water containing elevated sulfate (about 250 milligrams per liter) from quarry dewatering operations contributes to die increase in sulfate concentration (of 10 to 40 milligrams per liter) in base flow downstream from the quarry. The chloride load at all stream sites is greater than the load contributed by precipitation and mineral weathering to the basin, indicating anthropogenic sources of chloride throughout the basin. The diversity index of the benthic invertebrate community has increased since 1973 at the longterm biological monitoring site on West Valley Creek, indicating an improvement in stream quality. The improvement probably is related to controls on discharges and banning of pesticides, such as DOT, in the 1970's. Concentrations of dissolved constituents, except for chloride, determined for base flow in the autumn do not appear to have changed since 1971. Application of the seasonal Kendall test for trend indicates that concentrations of chloride in base flow have increased since 1971; this increase may be related to the increase in urbanization in the basin. The benthic community structure at the West Valley Creek site in 1991 indicates slight nutrient enrichment.Lithium was detected in ground water and surface water downgradient from two lithiumprocessing facilities. Until 1991, lithium was discharged into a losing reach of West Valley Creek, thus introducing lithium into the ground-water system. The potential for cross-contamination between the ground-water and surface-water systems is great, as demonstrated by the detection of lithium in ground water and surface water downstream and downgradient from the two lithium-processing facilities. The lithium that was discharged into the creek acts as a conservative tracer in gaining reaches of West Valley Creek, maintaining a mass balance and characteristic isotopic signature. Lithium-7/lithium-6 ratios were greater in streams that are affected by sewage and by lithium-processing discharges and in ground water downgradient from the lithium-processing facilities than natural background lithium isotopic ratios.

The impact of onsite wastewater disposal systems on groundwater in areas inundated by Hurricane Sandy in New York and New Jersey.

PubMed

Fisher, Irene J; Phillips, Patrick J; Colella, Kaitlyn M; Fisher, Shawn C; Tagliaferri, Tristen; Foreman, William T; Furlong, Edward T

2016-06-30

Coastal onsite wastewater disposal systems (OWDS) were inundated by Hurricane Sandy's storm tide. This study compares the shallow groundwater quality (nutrients, pharmaceuticals, and hormones) downgradient of OWDS before and after Hurricane Sandy, where available, and establishes a baseline for wastewater influence on groundwater in coastal communities inundated by Hurricane Sandy. Nutrients and contaminants of emerging concern (CECs) were detected in shallow groundwater downgradient of OWDS in two settings along the New Jersey and New York coastlines: 1) a single, centralized OWDS in a park; and 2) multiple OWDS (cesspools) in low-density residential and mixed-use/medium density residential areas. The most frequently detected pharmaceuticals were lidocaine (40%), carbamazepine (36%), and fexofenadine, bupropion, desvenlafaxine, meprobamate, and tramadol (24-32%). Increases in the number and total concentration of pharmaceuticals after Hurricane Sandy may reflect other factors (seasonality, usage) besides inundation, and demonstrate the importance of analyzing for a wide variety of CECs in regional studies. Published by Elsevier Ltd.

The impact of onsite wastewater disposal systems on groundwater in areas inundated by Hurricane Sandy in New York and New Jersey

USGS Publications Warehouse

Fisher, Irene; Phillips, Patrick J.; Colella, Kaitlyn; Fisher, Shawn C.; Tagliaferri, Tristen N.; Foreman, William T.; Furlong, Edward T.

2016-01-01

Coastal onsite wastewater disposal systems (OWDS) were inundated by Hurricane Sandy's storm tide. This study compares the shallow groundwater quality (nutrients, pharmaceuticals, and hormones) downgradient of OWDS before and after Hurricane Sandy, where available, and establishes a baseline for wastewater influence on groundwater in coastal communities inundated by Hurricane Sandy. Nutrients and contaminants of emerging concern (CECs) were detected in shallow groundwater downgradient of OWDS in two settings along the New Jersey and New York coastlines: 1) a single, centralized OWDS in a park; and 2) multiple OWDS (cesspools) in low-density residential and mixed-use/medium density residential areas. The most frequently detected pharmaceuticals were lidocaine (40%), carbamazepine (36%), and fexofenadine, bupropion, desvenlafaxine, meprobamate, and tramadol (24–32%). Increases in the number and total concentration of pharmaceuticals after Hurricane Sandy may reflect other factors (seasonality, usage) besides inundation, and demonstrate the importance of analyzing for a wide variety of CECs in regional studies.

Geophysical monitoring of a field-scale biostimulation pilot project

USGS Publications Warehouse

Lane, J.W.; Day-Lewis, F. D.; Casey, C.C.

2006-01-01

The USGS conducted a geophysical investigation in support of a U.S. Naval Facilities Engineering Command, Southern Division field-scale biostimulation pilot project at Anoka County Riverfront Park (ACP), downgradient of the Naval Industrial Reserve Ordnance Plant, Fridley, Minnesota. The goal of the pilot project is to evaluate subsurface injection of vegetable oil emulsion (VOE) to stimulate microbial degradation of chlorinated hydrocarbons. To monitor the emplacement and movement of the VOE and changes in water chemistry resulting from VOE dissolution and/or enhanced biological activity, the USGS acquired cross-hole radar zero-offset profiles, traveltime tomograms, and borehole geophysical logs during five site visits over 1.5 years. Analysis of pre- and postinjection data sets using petrophysical models developed to estimate VOE saturation and changes in total dissolved solids provides insights into the spatial and temporal distribution of VOE and ground water with altered chemistry. Radar slowness-difference tomograms and zero-offset slowness profiles indicate that the VOE remained close to the injection wells, whereas radar attenuation profiles and electromagnetic induction logs indicate that bulk electrical conductivity increased downgradient of the injection zone, diagnostic of changing water chemistry. Geophysical logs indicate that some screened intervals were located above or below zones of elevated dissolved solids; hence, the geophysical data provide a broader context for interpretation of water samples and evaluation of the biostimulation effort. Our results include (1) demonstration of field and data analysis methods for geophysical monitoring of VOE biostimulation and (2) site-specific insights into the spatial and temporal distributions of VOE at the ACP. ?? 2006 National Ground Water Association.

Investigation clogging dynamic of permeable pavement systems using embedded sensors

NASA Astrophysics Data System (ADS)

Razzaghmanesh, Mostafa; Borst, Michael

2018-02-01

Permeable pavement is a stormwater control measure commonly selected in both new and retrofit applications. However, there is limited information about the clogging mechanism of these systems that effects the infiltration. A permeable pavement site located at the Seitz Elementary School, on Fort Riley, Kansas was selected for this study. An 80-space parking lot was built behind the school as part of an EPA collaboration with the U.S. Army. The parking lot design includes a permeable interlocking concrete pavement section along the downgradient edge. This study monitored the clogging progress of the pavement section using twelve water content reflectometers and three buried tipping bucket rain gauges. This clogging dynamic investigation was divided into three stages namely pre-clogged, transitional, and clogged. Recorded initial relative water content of all three stages were significantly and negatively correlated to antecedent dry weather periods with stronger correlations during clogged conditions. The peak relative water content correlation with peak rainfall 10-min intensity was significant for the water content reflectometers located on the western edge away from the eastern edge; this correlation was strongest during transition stage. Once clogged, rainfall measurements no longer correlated with the buried tipping bucket rain gauges. Both water content reflectometers and buried tipping bucket rain gauges showed the progress of surface clogging. For every 6 mm of rain, clogging advanced 1 mm across the surface. The results generally support the hypothesis that the clogging progresses from the upgradient to the downgradient edge. The magnitude of the contributing drainage area and rainfall characteristics are effective factors on rate and progression of clogging.

Numerical simulation of ground-water flow in La Crosse County, Wisconsin, and into nearby pools of the Mississippi River

USGS Publications Warehouse

Hunt, Randall J.; Saad, David A.; Chapel, Dawn M.

2003-01-01

The models provide estimates of the locations and amount of ground-water flow into Pool 8 and the southern portion of Pool 7 of the Mississippi River. Ground-water discharges into all areas of the pools, except along the eastern shore in the vicinity of the city of La Crosse and immediately downgradient from lock and dam 7 and 8. Ground-water flow into the pools is generally greatest around the perimeter with decreasing amounts away from the perimeter. An area of relatively high ground-water discharge extends out towards the center of Pool 7 from the upper reaches of the pool and may

Potential effects of roadside dry wells on groundwater quality on the Island of Hawai'i-Assessment using numerical groundwater models

USGS Publications Warehouse

Izuka, Scot K.

2011-01-01

Widespread use of dry wells to dispose of roadside runoff has raised concern about the potential effects on the quality of groundwater on the Island of Hawai‘i. This study used semi-generic numerical models of groundwater flow and contaminant transport to assess the potential effect of dry wells on groundwater quality on the Island of Hawai‘i. The semi-generic models are generalized numerical groundwater-flow and solute-transport models that have a range of aquifer properties and regional groundwater gradients that are characteristic for the island. Several semi-generic models were created to study the effect of dry wells in different hydrogeologic conditions, such as different unsaturated-zone thicknesses or different aquifer characteristics. Results indicate that mixing of contaminated water from the surface with contaminant-free water in the saturated aquifer immediately reduces the contaminant concentration. The amount the concentration is reduced depends on the hydraulic properties of the aquifer in a given area, the thickness of the unsaturated zone, and whether the infiltration is focused in a small area of a dry well or spread naturally over a larger area. Model simulations indicate that focusing infiltration of contaminated runoff through a dry well can substantially increase contaminant concentrations in the underlying saturated aquifer relative to infiltration under natural conditions. Simulated concentrations directly beneath a dry well were nearly 8 times higher than the simulated concentrations directly beneath a broad infiltration area representing the natural condition. Where dry wells are present, contaminant concentrations in the underlying saturated aquifer are lower when the unsaturated zone is thicker and higher when the unsaturated zone is thinner. Contaminant concentrations decline quickly as the contaminant plume migrates, with the regional groundwater flow, away from the dry well. The differences among concentrations resulting from the various unsaturated-zone thicknesses also diminish with distance from the dry well. At a horizontal distance of about 700 ft downgradient from the dry well, all simulated maximum concentrations were less than 1 percent of the concentration in the infiltration water; at about 0.5 mi downgradient from the dry well, all simulated concentrations were equal to or less than 0.1 percent. Actual concentrations may be even lower than indicated by the models because of processes such as decay and reaction that were not simulated. Hydrologic and geologic differences from one location to the next also affect contaminant concentrations—simulations using models with properties representative of aquifers in the Hilo area resulted in lower overall concentrations than models with properties representative of aquifers in the Kona area. Results from this study can be used to assess how contaminants entering a dry well may affect receiving waters in a variety of situations on the Island of Hawai‘i. Better assessment would be obtained by using results from models having the most similar conditions (such as climate, hydraulic properties, regional groundwater gradient) to the dry well in question. The results of this study can help determine which dry wells are likely to have the greatest effect on nearby receiving waters and where more specific data and analyses may be needed.

The combined use of 87Sr/86Sr and carbon and water isotopes to study the hydrochemical interaction between groundwater and lakewater in mantled karst

NASA Astrophysics Data System (ADS)

Katz, Brian G.; Bullen, Thomas D.

1996-12-01

The hydrochemical interaction between groundwater and lakewater influences the composition of water that percolates downward from the surficial aquifer system through the underlying intermediate confining unit and recharges the Upper Floridan aquifer along highlands in Florida. The 87Sr/86Sr ratio along with the stable isotopes, D, 18O, and 13C were used as tracers to study the interaction between groundwater, lakewater, and aquifer minerals near Lake Barco, a seepage lake in the mantled karst terrane of northern Florida. Upgradient from the lake, the 87Sr/86Sr ratio of groundwater decreases with depth (mean values of 0.71004, 0.70890, and 0.70852 for water from the surficial aquifer system, intermediate confining unit, and Upper Floridan aquifer, respectively), resulting from the interaction of dilute oxygenated recharge water with aquifer minerals that are less radiogenic with depth. The concentrations of Sr2+ generally increase with depth, and higher concentrations of Sr2+ in water from the Upper Floridan aquifer (20-35 μg/L), relative to water from the surficial aquifer system and the intermediate confining unit, result from the dissolution of Sr-bearing calcite and dolomite in the Eocene limestone. Dissolution of calcite [δ13C= -1.6permil(‰)] is also indicated by an enriched δ13CDIC(-8.8 to -11.4 ‰) in water from the Upper Floridan aquifer, relative to the overlying hydrogeologic units (δ13CDIC< -16‰). Groundwater downgradient from Lake Barco was enriched in18O and D relative to groundwater upgradient from the lake, indicating mixing of lakewater leakage and groundwater. Downgradient from the lake, the 87Sr/86Sr ratio of groundwater and aquifer material become less radiogenic and the Sr2+ concentrations generally increase with depth. However, Sr2+ concentrations are substantially less than in upgradient groundwaters at similar depths. The lower Sr2+ concentrations result from the influence of anoxic lakewater leakage on the mobility of Sr2+ from clays. Based on results from mass-balance modeling, it is probable that cation exchange plays the dominant role in controlling the 87Sr/86Sr ratio of groundwater, both upgradient and downgradient from Lake Barco. Even though groundwater from the three distinct hydrogeologic units displays considerable variability in Sr concentration and isotopic composition, the dominant processes associated with the mixing of lakewater leakage with groundwater, as well as the effects of mineral-water interaction, can be ascertained by integrating the use of stable and radiogenic isotopic measurements of groundwater, lakewater, and aquifer minerals.

The Apache Longbow-Hellfire Missile Test at Yuma Proving Ground: Ecological Risk Assessment for Tracked Vehicle Movement across Desert Pavement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterson, Mark J; Efroymson, Rebecca Ann; Hargrove, William Walter

A multiple stressor risk assessment was conducted at Yuma Proving Ground, Arizona, as a demonstration of the Military Ecological Risk Assessment Framework. The focus was a testing program at Cibola Range, which involved an Apache Longbow helicopter firing Hellfire missiles at moving targets, M60-A1 tanks. This paper describes the ecological risk assessment for the tracked vehicle movement component of the testing program. The principal stressor associated with tracked vehicle movement was soil disturbance, and a resulting, secondary stressor was hydrological change. Water loss to washes and wash vegetation was expected to result from increased infiltration and/or evaporation associated with disturbancesmore » to desert pavement. The simulated exposure of wash vegetation to water loss was quantified using estimates of exposed land area from a digital ortho quarter quad aerial photo and field observations, a 30 30 m digital elevation model, the flow accumulation feature of ESRI ArcInfo, and a two-step process in which runoff was estimated from direct precipitation to a land area and from water that flowed from upgradient to a land area. In all simulated scenarios, absolute water loss decreased with distance from the disturbance, downgradient in the washes; however, percentage water loss was greatest in land areas immediately downgradient of a disturbance. Potential effects on growth and survival of wash trees were quantified by using an empirical relationship derived from a local unpublished study of water infiltration rates. The risk characterization concluded that neither risk to wash vegetation growth or survival nor risk to mule deer abundance and reproduction was expected. The risk characterization was negative for both the incremental risk of the test program and the combination of the test and pretest disturbances.« less

Arsenic transport between surface and groundwater in a moderately reducing zone: Geochemical approach

NASA Astrophysics Data System (ADS)

Khaska, Mahmoud; Le Gal La Salle, Corinne; Verdoux, Patrick

2015-04-01

Arsenic contamination represents a major risk to human health as one of the most prominent environmental causes of cancer mortality. Mining activities, particularly those involving arsenic rich ores have an impact on the environment and on human health that may persist for many decades after mine closure. The relationships between As released from alluvial aquifer in the vicinity of the sulfide-rich mine dumps was demonstrated with geochemical and isotopic tracers (major and traces elements, 87Sr/86Sr, 18O, 2H). Strontium isotopes were used to trace the transport of As downstream from a As rich tailing dam. Increasing As and Fe concentrations in surface water are explained by As release associated with alluvial groundwater discharge to the stream. This process occurs in a moderately reduced section of the stream downgradient from the sulfide-rich tailing dam. High As, total Fe and low Eh in groundwater confirm the discharge of alluvial groundwater and explain its impact on surface water. Transport of As between surface and groundwater can be described as follows: 1- Subsurface moderately reducing conditions prevail in groundwater downgradient from the tailing dams. This suggests a flux of reduced water from sulfide-rich tailing dams which is characterized by its high As and Fe content resulting from the reduction of Fe-sulfides. 2- Upon mixing with surface water, oxidizing conditions prevails and precipitate as Fe hydroxide on the stream bed. As and Sr subsequently adsorbed on the Fe -oxyhydroxide surface. This process contributes to the immobilization of As in surface water. Remaining dissolved As in surface water can be re-introduced in alluvial groundwater downstream of the reducing zone.

Simulation of groundwater flow and interaction of groundwater and surface water on the Lac du Flambeau Reservation, Wisconsin

USGS Publications Warehouse

Juckem, Paul F.; Fienen, Michael N.; Hunt, Randall J.

2014-01-01

The Lac du Flambeau Band of Lake Superior Chippewa and Indian Health Service are interested in improving the understanding of groundwater flow and groundwater/surface-water interaction on the Lac du Flambeau Reservation (Reservation) in southwest Vilas County and southeast Iron County, Wisconsin, with particular interest in an understanding of the potential for contamination of groundwater supply wells and the fate of wastewater that is infiltrated from treatment lagoons on the Reservation. This report describes the construction, calibration, and application of a regional groundwater flow model used to simulate the shallow groundwater flow system of the Reservation and water-quality results for groundwater and surface-water samples collected near a system of waste-water-treatment lagoons. Groundwater flows through a permeable glacial aquifer that ranges in thickness from 60 to more than 200 feet (ft). Seepage and drainage lakes are common in the area and influence groundwater flow patterns on the Reservation. A two-dimensional, steady-state analytic element groundwater flow model was constructed using the program GFLOW. The model was calibrated by matching target water levels and stream base flows through the use of the parameter-estimation program, PEST. Simulated results illustrate that groundwater flow within most of the Reservation is toward the Bear River and the chain of lakes that feed the Bear River. Results of analyses of groundwater and surface-water samples collected downgradient from the wastewater infiltration lagoons show elevated levels of ammonia and dissolved phosphorus. In addition, wastewater indicator chemicals detected in three downgradient wells and a small downgradient stream indicate that infiltrated wastewater is moving southwest of the lagoons toward Moss Lake. Potential effects of extended wet and dry periods (within historical ranges) were evaluated by adjusting precipitation and groundwater recharge in the model and comparing the resulting simulated lake stage and water budgets to stages and water budgets from the calibrated model. Simulated lake water budgets and water level changes illustrate the importance of understanding the position of a lake within the hydrologic system (headwater or downstream), the type of lake (surface-water drainage or seepage lake), and the role of groundwater in dampening the effects of large-scale changes in weather patterns on lake levels. Areas contributing recharge to drinking-water supply wells on the Reservation were delineated using forward particle tracking from the water table to the well. Monte Carlo uncertainty analyses were used to produce maps showing the probability of groundwater capture for areas around each well nest. At the Main Pumphouse site near the Village of Lac du Flambeau, most of the area contributing recharge to the wells occurs downgradient from a large wetland between the wells and the wastewater infiltration lagoons. Nonetheless, a small potential for the wells to capture infiltrated wastewater is apparent when considering uncertainty in the model parameter values. At the West Pumphouse wells south of Flambeau Lake, most of the area contributing recharge is between the wells and Tippecanoe Lake. The extent of infiltrated wastewater from two infiltration lagoons was tracked using the groundwater flow model and Monte Carlo uncertainty analyses. Wastewater infiltrated from the lagoons flows predominantly south toward Moss Lake as it integrates with the regional groundwater flow system. The wastewater-plume-extent simulations support the area-contributing-recharge simulations, indicating that there is a possibility, albeit at low probability, that some wastewater could be captured by water-supply wells. Comparison of simulated water-table contours indicate that the lagoons may mound the water table approximately 4 ft, with diminishing levels of mounding outward from the lagoons. Four scenarios, representing potential alternatives for wastewater management, were simulated (at current discharge rates) to evaluate the potential extent of wastewater in the aquifer and discharge to surface-water bodies associated with each management scenario. Wastewater simulated to infiltrate through a hypothetical diffuser below a wetland south of the current lagoons appears to discharge to the overlying wetland and would likely discharge to Moss Lake as overland flow. Wastewater simulated to discharge to a small lake (Mindy Lake) between Moss and Fence Lakes appears to spread radically over a large area between the lakes. Wastewater simulated to discharge to lagoons south and northeast of the current lagoons also appears to spread radially, but the areas of the aquifer with the highest probability of encountering waste-water contamination would likely be between the lagoons and the nearest lake, where the wastewater would eventually discharge. Probability results for the wastewater-plume-extent scenarios are sensitive to the number of mathematical water particles used to represent infiltrating wastewater and the level of detail in the synthetic grid used for the probability analysis. Thus, probability results from wastewater-plume-extent simulations are qualitative only; however, it is expected that illustrations of relatively high or low probability will be useful as a general guide for decision making. Management problems requiring quantitative estimates of probability are best re-cast into problems evaluating the area that contributes recharge to the location of interest, which is not dependent upon the number of simulated particles or the resolution of a synthetic grid.

Flow and geochemistry along shallow ground-water flowpaths in an agricultural area in southeastern Wisconsin

USGS Publications Warehouse

Saad, D.A.; Thorstenson, D.C.

1998-01-01

Ground water recharging at mid- and downgradient wells is oxic and contains dissolved nitrate, whereas the ground water discharging to the stream is anoxic and contains dissolved ammonium. Redox environments were defined at each well on the basis of relative concentrations of various dissolved redox-active species. Chemically permissible flowpaths inferred from the observed sequence of redox environments at well sites are consistent with flowpaths in the ground-water flow model. The transition from nitrate in recharging ground water to ammonium in ground water discharging to the stream suggests the possibility of nitrate reduction along the flowpath. None of the techniques employed in this study, however, were able to prove the occurrence of this reaction.

Associations of free-living bacteria and dissolved organic compounds in a plume of contaminated groundwater

USGS Publications Warehouse

Harvey, R.W.; Barber, L.B.; ,

1992-01-01

Associations of free-living bacteria (FLB) and dissolved organic contaminants in a 4-km-long plume of sewage-contaminated groundwater were investigated. Abundance of FLB in the core of the plume (as delineated by maximum specific conductance) steadily decreased in the direction of flow from a point 0.25 km downgradient from the source to the toe of the plume. At 0.25 km downgradient, FLB comprised up to 31% of the total bacterial population, but constituted < 7% of the population at 2 km downgradient. Abundance of FLB correlated strongly (r = 0.80 n = 23) with total dissolved organic carbon (DOC) in contaminated groundwater between 0.64 and 2.1 km downgradient, although distributions of individual contaminants such as di-, tri- and tetrachloroethene were highly variable, and their association with FLB less clear. Numbers of FLB in the downgradient portion of the plume which is contaminated with branched-chain alkylbenzenesulfonate (ABS) surfactants were low (< 5??108/L) in spite of relatively high levels of DOC (up to 4 mg/L). However, abundance of FLB correlated strongly with non-surfactant DOC along vertical transects through the plume. The ratio of FLB to DOC and the ratio of FLB to attached bacteria generally decreased in the direction of flow and, consequently, with the age of the organic contaminants.

Reactive transport modeling of geochemical controls on secondary water quality impacts at a crude oil spill site near Bemidji, MN

USGS Publications Warehouse

Ng, Gene-Hua Crystal.; Bekins, Barbara A.; Cozzarelli, Isabelle M.; Baedecker, Mary Jo; Bennett, Philip C.; Amos, Richard T.; Herkelrath, William N.

2015-01-01

Anaerobic biodegradation of organic amendments and contaminants in aquifers can trigger secondary water quality impacts that impair groundwater resources. Reactive transport models help elucidate how diverse geochemical reactions control the spatiotemporal evolution of these impacts. Using extensive monitoring data from a crude oil spill site near Bemidji, Minnesota (USA), we implemented a comprehensive model that simulates secondary plumes of depleted dissolved O2 and elevated concentrations of Mn2+, Fe2+, CH4, and Ca2+ over a two-dimensional cross section for 30 years following the spill. The model produces observed changes by representing multiple oil constituents and coupled carbonate and hydroxide chemistry. The model includes reactions with carbonates and Fe and Mn mineral phases, outgassing of CH4 and CO2 gas phases, and sorption of Fe, Mn, and H+. Model results demonstrate that most of the carbon loss from the oil (70%) occurs through direct outgassing from the oil source zone, greatly limiting the amount of CH4 cycled down-gradient. The vast majority of reduced Fe is strongly attenuated on sediments, with most (91%) in the sorbed form in the model. Ferrous carbonates constitute a small fraction of the reduced Fe in simulations, but may be important for furthering the reduction of ferric oxides. The combined effect of concomitant redox reactions, sorption, and dissolved CO2 inputs from source-zone degradation successfully reproduced observed pH. The model demonstrates that secondary water quality impacts may depend strongly on organic carbon properties, and impacts may decrease due to sorption and direct outgassing from the source zone.

Calculating ground water transit time of horizontal flow through leaky aquifers.

PubMed

Braunsfurth, Angelika C; Schneider, Wilfried

2008-01-01

The calculation of ground water transit times is one important factor in ground water protection. In this paper, we present an analytical solution for the transit time for a Dupuit-type flow system applicable to saturated flow through a horizontal leaky aquifer discharging to a downgradient fixed-head boundary under steady-state conditions. We investigate the influence of leakage when comparing the resulting travel times of our model based on head-dependent leakage with the commonly used model with no leakage and a simplified model with constant leakage. The results show significant differences in the position of the water divide and transit time, suggesting that leakage cannot be ignored.

Hydraulic and geochemical performance of a permeable reactive barrier containing zero-valent iron, Denver Federal Center

USGS Publications Warehouse

McMahon, P.B.; Dennehy, K.F.; Sandstrom, M.W.

1999-01-01

The hydraulic and geochemical performance of a 366 m long permeable reactive barrier (PRB) at the Denver Federal Center; Denver, Colorado, was evaluated. The funnel and gate system, which was installed in 1996 to intercept and remediate ground water contaminated with chlorinated aliphatic hydrocarbons (CAHs), contained four 12.2 m wide gates filled with zero-valent iron. Ground water mounding on the upgradient side of the PRB resulted in a tenfold increase in the hydraulic gradient and ground water velocity through the gates compared to areas of the aquifer unaffected by the PRB. Water balance calculations for April 1997 indicate that about 75% of the ground water moving toward the PRB from upgradient areas moved through the gates. The rest of the water either accumulated on the upgradient side of the PRB or bypassed the PRB. Chemical data from monitoring wells screened down-gradient, beneath, and at the ends of the PRB indicate that contaminants had not bypassed the PRB, except in a few isolated areas. Greater than 99% of the CAH mass entering the gates was retained by the iron. Fifty-one percent of the CAH carbon entering one gate was accounted for in dissolved C1 and C2 hydrocarbons, primarily ethane and ethene, which indicates that CAHs may adsorb to the iron prior to being dehalogenated. Treated water exiting the gates displaced contaminated ground water at a distance of at least 3 m downgradient from the PRB by the end of 1997. Measurements of dissolved inorganic ions in one gate indicate that calcite and siderite precipitation in the gate could reduce gate porosity by about 0.35% per year. Results from this study indicate that funnel and gate systems containing zero-valent iron can effectively treat ground water contaminated with CAHs. However, the hydrologic impacts of the PRB on the flow system need to be fully understood to prevent contaminants from bypassing the PRB.

Geophysical monitoring of a field-scale biostimulation pilot project.

PubMed

Lane, John W; Day-Lewis, Frederick D; Casey, Clifton C

2006-01-01

The USGS conducted a geophysical investigation in support of a U.S. Naval Facilities Engineering Command, Southern Division field-scale biostimulation pilot project at Anoka County Riverfront Park (ACP), down-gradient of the Naval Industrial Reserve Ordnance Plant, Fridley, Minnesota. The goal of the pilot project is to evaluate subsurface injection of vegetable oil emulsion (VOE) to stimulate microbial degradation of chlorinated hydrocarbons. To monitor the emplacement and movement of the VOE and changes in water chemistry resulting from VOE dissolution and/or enhanced biological activity, the USGS acquired cross-hole radar zero-offset profiles, travel-time tomograms, and borehole geophysical logs during five site visits over 1.5 years. Analysis of pre- and postinjection data sets using petrophysical models developed to estimate VOE saturation and changes in total dissolved solids provides insights into the spatial and temporal distribution of VOE and ground water with altered chemistry. Radar slowness-difference tomograms and zero-offset slowness profiles indicate that the VOE remained close to the injection wells, whereas radar attenuation profiles and electromagnetic induction logs indicate that bulk electrical conductivity increased down-gradient of the injection zone, diagnostic of changing water chemistry. Geophysical logs indicate that some screened intervals were located above or below zones of elevated dissolved solids; hence, the geophysical data provide a broader context for interpretation of water samples and evaluation of the biostimulation effort. Our results include (1) demonstration of field and data analysis methods for geophysical monitoring of VOE biostimulation and (2) site-specific insights into the spatial and temporal distributions of VOE at the ACP.

Shallow ground-water quality adjacent to burley tobacco fields in northeastern Tennessee and southwestern Virginia, spring 1997

USGS Publications Warehouse

Johnson, G.C.; Connell, J.F.

2001-01-01

In 1994, the U.S. Geological Survey began an assessment of the upper Tennessee River Basin as part of the National Water-Quality Assessment (NAWQA) Program. A ground-water land-use study conducted in 1996 focused on areas with burley tobacco production in northeastern Tennessee and southwestern Virginia. Land-use studies are designed to focus on specific land uses and to examine natural and human factors that affect the quality of shallow ground water underlying specific types of land use. Thirty wells were drilled in shallow regolith adjacent to and downgradient of tobacco fields in the Valley and Ridge Physiographic Province of the upper Tennessee River Basin. Ground-water samples were collected between June 4 and July 9, 1997, to coincide with the application of the majority of pesticides and fertilizers used in tobacco production. Ground-water samples were analyzed for nutrients, major ions, 79 pesticides, 7 pesticide degradation products, 86 volatile organic compounds, and dissolved organic carbon. Nutrient concentrations were lower than the levels found in similar NAWQA studies across the United States during 1993-95. Five of 30 upper Tennessee River Basin wells (16.7 percent) had nitrate levels exceeding 10 mg/L while 19 percent of agricultural land-use wells nationally and 7.9 percent in the Southeast had nitrate concentrations exceeding 10 mg/L. Median nutrient concentrations were equal to or less than national median concentrations. All pesticide concentrations in the basin were less than established drinking water standards, and pesticides were detected less frequently than average for other NAWQA study units. Atrazine was detected at 8 of 30 (27 percent) of the wells, and deethylatrazine (an atrazine degradation product) was found in 9 (30 percent) of the wells. Metalaxyl was found in 17 percent of the wells, and prometon, flumetralin, dimethomorph, 2,4,5-T, 2,4-D, dichlorprop, and silvex were detected once each (3 percent). Volatile organic compounds were detected in 27 of 30 wells. Although none of the volatile organic compound concentrations exceeded drinking water standards, the detection frequency was higher than the average for the other NAWQA study units.

Transport and fate of nitrate and pesticides: Hydrogeology and riparian zone processes

USGS Publications Warehouse

Puckett, L.J.; Hughes, W.B.

2005-01-01

There is continuing concern over potential impacts of widespread application of nutrients and pesticides on ground- and surface-water quality. Transport and fate of nitrate and pesticides were investigated in a shallow aquifer and adjacent stream, Cow Castle Creek, in Orangeburg County, South Carolina. Pesticide and pesticide degradate concentrations were detected in ground water with greatest frequency and largest concentrations directly beneath and downgradient from the corn (Zea mays L.) field where they were applied. In almost all samples in which they were detected, concentrations of pesticide degradates greatly exceeded those of parent compounds, and were still present in ground waters that were recharged during the previous 18 yr. The absence of both parent and degradate compounds in samples collected from deeper in the aquifer suggests that this persistence is limited or that the ground water had recharged before use of the pesticide. Concentrations of NO3- in ground water decreased with increasing depth and age, but denitrification was not a dominant controlling factor. Hydrologic and chemical data indicated that ground water discharges to the creek and chemical exchange takes place within the upper 0.7 m of the streambed. Ground water had its greatest influence on surface-water chemistry during low-flow periods, causing a decrease in concentrations of Cl-, NO3-, pesticides, and pesticide degradates. Conversely, shallow subsurface drainage dominates stream chemistry during high-flow periods, increasing stream concentrations of Cl-, NO3-, pesticides, and pesticide degradates. These results point out the importance of understanding the hydrogeologic setting when investigating transport and fate of contaminants in ground water and surface water. ?? ASA, CSSA, SSSA.

Hydrogeology and soil gas at J-Field, Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Hughes, W.B.

1993-01-01

Disposal of chemical warfare agents, munitions, and industrial chemicals in J-Field, Aberdeen Proving Ground, Maryland, has contaminated soil, groundwater and surface water. Seven exploratory borings and 38 observation wells were drilled to define the hydrogeologic framework at J-Field and to determine the type, extent, and movement of contaminants. The geologic units beneath J-Field consist of Coastal Plain sediments of the Cretaceous Patapsco Formation and Pleistocene Talbot Formation. The Patapsco Formation contains several laterally discontinuous aquifers and confining units. The Pleistocene deposits were divided into 3 hydrogeologic units--a surficial aquifer, a confining unit, and a confined aquifer. Water in the surficial aquifer flows laterally from topographically high areas to discharge areas in marshes and streams, and vertically to the underlying confined aquifer. In offshore areas, water flows from the deeper confined aquifers upward toward discharge areas in the Gunpowder River and Chesapeake Bay. Analyses of soil-gas samples showed high relative-flux values of chlorinated solvents, phthalates, and hydrocarbons at the toxic-materials disposal area, white-phosphorus disposal area, and riot-control-agent disposal area. The highest flux values were located downgradient of the toxic materials and white phosphorus disposal areas, indicating that groundwater contaminants are moving from source areas beneath the disposal pits toward discharge points in the marshes and estuaries. Elevated relative-flux values were measured upgradient and downgradient of the riot-control agent disposal area, and possibly result from soil and (or) groundwater contamination.

Movement and fate of creosote waste in ground water, Pensacola, Florida; U.S. Geological Survey toxic waste-ground-water contamination program

USGS Publications Warehouse

Mattraw, Harold C.; Franks, Bernard J.

1986-01-01

Ground- and surface-water contamination by pesticides used in the wood-preserving industry is widespread in the United States. Pine poles were treated with wood preservatives from 1902 to 1981 at a creosote works near Pensacola, Florida. Diesel fuel, creosote, and pentachlorophenol were discharged to two unlined impoundments that had a direct hydraulic connection to the sand-and-gravel aquifer. Evidence of wood-preserving waste contamination appears to be confined to the upper 30 meters of the aquifer. The waste plume extends downgradient approximately 300 meters south toward Pensacola Bay. In 1983, the creosote works site was selected by the U.S. Geological Survey's Office of Hazardous Waste Hydrology as a national research demonstration area to apply the latest techniques for characterizing hazardous waste problems. The multidisciplinary research effort is aimed at studying processes that affect the occurrence, transport, transformations, and fate of the toxic contaminants associated with wood preservatives in the environment. Clusters of two to five wells were constructed at different depths at nine sites to define the depth of contamination. Research studies are investigating sorption, dispersion, dilution, chemical reactions, bacterially mediated transformations, quality assurance, plume hydrodynamics, and the ultimate fate of these complex organic wastes.

Arsenic in glacial drift aquifers and the implication for drinking water - Lower Illinois River Basin

USGS Publications Warehouse

Warner, K.L.

2001-01-01

The lower Illinois River Basin (LIRB) covers 47,000 km2 of central and western Illinois. In the LIRB, 90% of the ground water supplies are from the deep and shallow glacial drift aquifers. The deep glacial drift aquifer (DGDA) is below 152 m altitude, a sand and gravel deposit that fills the Mahomet Buried Bedrock Valley, and overlain by more than 30.5 m of clayey till. The LIRB is part of the USGS National Water Quality Assessment program, which has an objective to describe the status and trends of surface and ground water quality. In the DGDA, 55 % of the wells used for public drinking-water supply and 43 % of the wells used for domestic drinking water supply have arsenic concentrations above 10 ??g/L (a new U.S. EPA drinking water standard). Arsenic concentrations greater than 25 ??g/L in ground water are mostly in the form of arsenite (AsIII). The proportion of arsenate (AsV) to arsenite does not change along the flowpath of the DGDA. Because of the limited number of arsenic species analyses, no clear relations between species and other trace elements, major ions, or physical parameters could be established. Arsenic and barium concentrations increase from east to west in the DGDA and are positively correlated. Chloride and arsenic are positively correlated and provide evidence that arsenic may be derived locally from underlying bedrock. Solid phase geochemical analysis of the till, sand and gravel, and bedrock show the highest presence of arsenic in the underlying organic-rich carbonate bedrock. The black shale or coal within the organic-rich carbonate bedrock is a potential source of arsenic. Most high arsenic concentrations found in the DGDA are west and downgradient of the bedrock structural features. Geologic structures in the bedrock are potential pathways for recharge to the DGDA from surrounding bedrock.

Associations of free-living bacteria and dissolved organic compounds in a plume of contaminated groundwater

USGS Publications Warehouse

Harvey, Ronald W.; Barber, Larry B.

1992-01-01

Associations of free-living bacteria (FLB) and dissolved organic contaminants in a 4-km-long plume of sewage-contaminated groundwater were investigated. Abundance of FLB in the core of the plume (as delineated by maximum specific conductance) steadily decreased in the direction of flow from a point 0.25 km downgradient from the source to the toe of the plume. At 0.25 km downgradient, FLB comprised up to 31% of the total bacterial population, but constituted <7% of the population at 2 km downgradient. Abundance of FLB correlated strongly (r = 0.80, n = 23) with total dissolved organic carbon (DOC) in contaminated groundwater between 0.64 and 2.1 km downgradient, although distributions of individual contaminants such as di-, tri- and tetrachloroethene were highly variable, and their association with FLB less clear. Numbers of FLB in the downgradient portion of the plume which is contaminated with branched-chain alkylbenzenesulfonate (ABS) surfactants were low (<5 · 108/L) in spite of relatively high levels of DOC (up to 4 mg/L). However, abundance of FLB correlated strongly with non-surfactant DOC along vertical transects through the plume. The ratio of FLB to DOC and the ratio of FLB to attached bacteria generally decreased in the direction of flow and, consequently, with the age of the organic contaminants.

Numerical simulation of steady state three-dimensional groundwater flow near lakes

USGS Publications Warehouse

Winter, Thomas C.

1978-01-01

Numerical simulation of three-dimensional groundwater flow near lakes shows that the continuity of the boundary encompassing the local groundwater flow system associated with a lake is the key to understanding the interaction of a lake with the groundwater system. The continuity of the boundary can be determined by the presence of a stagnation zone coinciding with the side of the lake nearest the downgradient side of the groundwater system. For most settings modeled in this study the stagnation zone underlies the lakeshore, and it generally follows its curvature. The length of the stagnation zone is controlled by the geometry of the lake's drainage basin divide on the side of the lake nearest the downgradient side of the groundwater system. In the case of lakes that lose water to the groundwater system, three-dimensional modeling also allows for estimating the area of lake bed through which outseepage takes place. Analysis of the effects of size and lateral and vertical distribution of aquifers within the groundwater system on the outseepage from lakes shows that the position of the center point of the aquifer relative to the littoral zone on the side of the lake nearest the downgradient side of the groundwater system is a critical factor. If the center point is downslope from this part of the littoral zone, the local flow system boundary tends to be weak or outseepage occurs. If the center point is upslope from this littoral zone, the stagnation zone tends to be stronger (to have a higher head in relation to lake level), and outseepage is unlikely to occur.

Spatial and temporal migration of a landfill leachate plume in alluvium

USGS Publications Warehouse

Masoner, Jason R.; Cozzarelli, Isabelle M.

2015-01-01

Leachate from unlined or leaky landfills can create groundwater contaminant plumes that last decades to centuries. Understanding the dynamics of leachate movement in space and time is essential for monitoring, planning and management, and assessment of risk to groundwater and surface-water resources. Over a 23.4-year period (1986–2010), the spatial extent of the Norman Landfill leachate plume increased at a rate of 7800 m2/year and expanded by 878 %, from an area of 20,800 m2 in 1986 to 203,400 m2 in 2010. A linear plume velocity of 40.2 m/year was calculated that compared favorably to a groundwater-seepage velocity of 55.2 m/year. Plume-scale hydraulic conductivity values representative of actual hydrogeological conditions in the alluvium ranged from 7.0 × 10−5 to 7.5 × 10−4 m/s, with a median of 2.0 × 10−4 m/s. Analyses of field-measured and calculated plume-scale hydraulic conductivity distributions indicate that the upper percentiles of field-measured values should be considered to assess rates of plume-scale migration, spreading, and biodegradation. A pattern of increasing Cl− concentrations during dry periods and decreasing Cl− concentrations during wet periods was observed in groundwater beneath the landfill. The opposite occurred in groundwater downgradient from the landfill; that is, Cl− concentrations in groundwater downgradient from the landfill decreased during dry periods and increased during wet periods. This pattern of changing Cl−concentrations in response to wet and dry periods indicates that the landfill retains or absorbs leachate during dry periods and produces lower concentrated leachate downgradient. During wet periods, the landfill receives more recharge which dilutes leachate in the landfill but increases leachate migration from the landfill and produces a more concentrated contaminant plume. This approach of quantifying plume expansion, migration, and concentration during variable hydrologic conditions provides increased understanding of plume behavior and migration potential and may be applied at less monitored landfill sites to evaluate potential risks of contamination to downgradient receptors.

Ground-water-quality assessment of shallow aquifers in the Front Range Urban Corridor, Colorado, 1954-98

USGS Publications Warehouse

Flynn, Jennifer L.

2003-01-01

Historical (1954-98) water-quality data for major ions, trace elements, major plant nutrients, and organic constituents collected in 3,870 sampling events at 2,138 shallow wells represent ground-water quality in shallow aquifers that underlie the Front Range Urban Corridor in Colorado. Nonparametric summary statistics and maps of concentrations across the study area indicate that ground water in the study area included fresh to saline water. Sulfate concentrations were elevated in the north and northeast parts of the study area, possibly due to Pierre Shale and Laramie Formation shale outcrops in those areas. Apart from isolated areas of known contamination, chloride concentrations were generally less than 100 milligrams per liter across the study area. Wells with elevated nitrate concentrations usually were located near rivers and streams downgradient from metropolitan areas. Elevated nitrate concentrations in wells that were not along the South Platte River were possibly from individual sewage disposal system usage or from fertilizer application to land. Spatial distribution for organic compounds for which more than 40 percent of the data were above the detection limit (atrazine, methyl-tert-butylether, and prometon) is not widespread across the study area, but this may reflect limitations of data availability. Summary statistics calculated or estimated by decade are influenced by the temporal variability of data across the study area. The median values of specific conductance, chloride, and nitrate from the 1970?s are less than values from the 1980?s and 1990?s, which, because most samples from the l970?s were collected in the western part of the study area, indicates that water quality in the western part of the study area is generally different than the rest of the study area. Chloride may be introduced to ground water from runoff of road deicers or chlorinated organics in transportation/transitional areas, where the median concentration is the greatest (85.0 milligrams per liter). Nitrate median concentrations are several times greater where the land is cultivated or used for agricultural business, which may reflect use of nitrogen fertilizers and the presence of animal feeding operations. Most inorganic and organic constituents exceeded drinking-water standards in only a small percentage of samples. Exceptions to this include sulfate; nitrate; trace elements aluminum, cadmium, iron, and manganese; and organic compounds 1,1-dichloroethylene, tetrachloroethylene, trichloroethylene, benzene, and dichloromethane.

Predicting Mountainous Watershed Biogeochemical Dynamics, Including Response to Droughts and Early Snowmelt

NASA Astrophysics Data System (ADS)

Hubbard, S. S.; Williams, K. H.; Long, P.; Agarwal, D.; Banfield, J. F.; Beller, H. R.; Bouskill, N.; Brodie, E.; Maxwell, R. M.; Nico, P. S.; Steefel, C. I.; Steltzer, H.; Tokunaga, T. K.; Wainwright, H. M.

2016-12-01

Climate change, extreme weather, land-use change, and other perturbations are significantly reshaping interactions with in watersheds throughout the world. While mountainous watersheds are recognized as the water towers for the world, hydrological processes in watersheds also mediate biogeochemical processes that support all terrestrial life. Developing predictive understanding of watershed hydrological and biogeochemical functioning is challenging, as complex interactions occurring within a heterogeneous watershed can lead to a cascade of effects on downstream water availability and quality. Although these interactions can have significant implications for energy production, agriculture, water quality, and other benefits valued by society, uncertainty associated with predicting watershed function is high. The Watershed Function project aims to substantially reduce this uncertainty through developing a predictive understanding of how mountainous watersheds retain and release downgradient water, nutrients, carbon, and metals. In particular, the project is exploring how early snowmelt, drought, and other disturbances will influence mountainous watershed dynamics at seasonal to decadal timescales. The Watershed Function project is being carried out in a headwater mountainous catchment of the Upper Colorado River Basin, within a watershed characterized by significant gradients in elevation, vegetation and hydrogeology. A system-within system project perspective posits that the integrated watershed response to disturbances can be adequately predicted through consideration of interactions and feedbacks occurring within a limited number of subsystems, each having distinct vegetation-subsurface biogeochemical-hydrological characteristics. A key technological goal is the development of scale-adaptive simulation capabilities that can incorporate genomic information where and when it is useful for predicting the overall watershed response to disturbance. Through developing and integrating new microbial ecology, geochemical, hydrological, ecohydrological, computational and geophysical approaches, the project is developing new insights about biogeochemical dynamics from genome to watershed scales.

Impact of stormwater infiltration basins on groundwater quality, Perth metropolitan region, Western Australia

NASA Astrophysics Data System (ADS)

Appleyard, S. J.

1993-08-01

Twelve bores were sunk adjacent to three stormwater infiltration basins in the Perth metropolitan area to examine the impact of runoff from a light industrial area, a medium-density residential area, and a major arterial road on groundwater quality, and to examine the hydrological response of the aquifer to runoff recharge. Automatic and manual water level monitoring between April and November 1990 indicated that groundwater levels responded within minutes to recharge from the infiltration basins. Peak water levels of up to 2.5 m above rest levels occurred 6 24 h after the commencement of ponding in the infiltration basins. There was a marked reduction in salinity and increase in dissolved oxygen concentrations in the upper part of the aquifer downgradient of the infiltration basins. Concentrations of toxic metals, nutrients, pesticides, and phenolic compounds in groundwater near the infiltration basins were low and generally well within Australian drinking water guidelines. However, sediment in the base of an infiltration basin draining a major road contained in excess of 3500 ppm of lead. Phthalates, which are US EPA priority pollutants, were detected in all but one bore near the infiltration basins. Their detection may be a sampling artifact, but they may also be derived from the plastic litter that accumulates in the infiltration basins. The concentration of iron in groundwater near the infiltration basins appears to be controlled by dissolved oxygen concentrations, with high iron concentrations occurring where dissolved oxygen concentrations are low. Pumping bores located near infiltration basins may suffer from iron encrustation problems caused by the mixing of shallow, oxygenated groundwater with water containing higher concentrations of iron from deeper in the aquifer.

Evaluation of hydrogeology and hydrogeochemistry of Truckee Meadows area, Washoe County, Nevada

USGS Publications Warehouse

Cohen, Philip M.; Loeltz, Omar J.

1964-01-01

Practically all the ground water of economic importance in the Truckee Meadows area, an alluviated intermontane basin in western Nevada is in the valley fill, which consists of unconsolidated and partially consolidated sedimentary deposits. The Mesozoic and Cenozoic consolidated rocks of the mountains bordering the valley contain some water in fractures and other openings, but they have virtually no interstitial permeability. The permeability of the valley fill is extremely variable. The Truckee Formation, which is the oldest deposit of the valley fill, yields very little water to wells. Permeable lenses of sand and gravel in the valley fill that are younger than the Truckee Formation yield moderate to large amounts of water to wells. The estimated average annual recharge to and discharge from the groundwater reservoir is 35,000 acre-feet. About 25,000 acre-feet of the recharge is from the infiltration of irrigation water diverted from the Truckee River. Most of the discharge is by evapotranspiration and by seepage to ditches and streams. Some water in the area is unsuitable for many uses because of its poor chemical quality. Water in the Steamboat Springs area is hot and has high concentrations of chloride and dissolved solids. Both water draining areas of bleached rock and ground water downgradient from areas of leached rock have high concentrations of sulfate and dissolved solids. Surface water of low dissolved-solids content mixes with and dilutes some highly mineralized ground water. Increased pumping in discharge areas will help to alleviate waterlogged conditions and will decrease ground-water losses by evapotranspiration. Increased pumping near the Truckee River may induce recharge from the river to the ground-water system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The 20-acre White Farm Equipment Dump site is an active landfill near the north border of Charles City in Floyd County, Iowa. Drainage from the site toward the northwest and south feeds into adjacent wetland areas. The Charles City municipal wells, located 700 feet east of the site, obtain water from the deep, confined Cedar Valley aquifer. Additionally, six shallow drinking water wells that draw from an uncontrolled water table are 1,000 feet downgradient from the site. Intermittently since 1971, approximately 650,000 cubic yards of wet scrubber sludges, foundry sands, baghouse dusts, and other industrial wastes were disposed of onsite.more » The primary contaminants of concern affecting the soil, debris, and ground water are VOCs including benzene and toluene; and metals including arsenic, lead, and chromium.« less

Assessing the chemical contamination dynamics in a mixed land use stream system.

PubMed

Sonne, Anne Th; McKnight, Ursula S; Rønde, Vinni; Bjerg, Poul L

2017-11-15

Traditionally, the monitoring of streams for chemical and ecological status has been limited to surface water concentrations, where the dominant focus has been on general water quality and the risk for eutrophication. Mixed land use stream systems, comprising urban areas and agricultural production, are challenging to assess with multiple chemical stressors impacting stream corridors. New approaches are urgently needed for identifying relevant sources, pathways and potential impacts for implementation of suitable source management and remedial measures. We developed a method for risk assessing chemical stressors in these systems and applied the approach to a 16-km groundwater-fed stream corridor (Grindsted, Denmark). Three methods were combined: (i) in-stream contaminant mass discharge for source quantification, (ii) Toxic Units and (iii) environmental standards. An evaluation of the chemical quality of all three stream compartments - stream water, hyporheic zone, streambed sediment - made it possible to link chemical stressors to their respective sources and obtain new knowledge about source composition and origin. Moreover, toxic unit estimation and comparison to environmental standards revealed the stream water quality was substantially impaired by both geogenic and diffuse anthropogenic sources of metals along the entire corridor, while the streambed was less impacted. Quantification of the contaminant mass discharge originating from a former pharmaceutical factory revealed that several 100 kgs of chlorinated ethenes and pharmaceutical compounds discharge into the stream every year. The strongly reduced redox conditions in the plume result in high concentrations of dissolved iron and additionally release arsenic, generating the complex contaminant mixture found in the narrow discharge zone. The fingerprint of the plume was observed in the stream several km downgradient, while nutrients, inorganics and pesticides played a minor role for the stream health. The results emphasize that future investigations should include multiple compounds and stream compartments, and highlight the need for holistic approaches when risk assessing these dynamic systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

GeoChip-based analysis of microbial functional gene diversity in a landfill leachate-contaminated aquifer

USGS Publications Warehouse

Lu, Zhenmei; He, Zhili; Parisi, Victoria A.; Kang, Sanghoon; Deng, Ye; Van Nostrand, Joy D.; Masoner, Jason R.; Cozzarelli, Isabelle M.; Suflita, Joseph M.; Zhou, Jizhong

2012-01-01

The functional gene diversity and structure of microbial communities in a shallow landfill leachate-contaminated aquifer were assessed using a comprehensive functional gene array (GeoChip 3.0). Water samples were obtained from eight wells at the same aquifer depth immediately below a municipal landfill or along the predominant downgradient groundwater flowpath. Functional gene richness and diversity immediately below the landfill and the closest well were considerably lower than those in downgradient wells. Mantel tests and canonical correspondence analysis (CCA) suggested that various geochemical parameters had a significant impact on the subsurface microbial community structure. That is, leachate from the unlined landfill impacted the diversity, composition, structure, and functional potential of groundwater microbial communities as a function of groundwater pH, and concentrations of sulfate, ammonia, and dissolved organic carbon (DOC). Historical geochemical records indicate that all sampled wells chronically received leachate, and the increase in microbial diversity as a function of distance from the landfill is consistent with mitigation of the impact of leachate on the groundwater system by natural attenuation mechanisms.

Augmenting groundwater monitoring networks near landfills with slurry cutoff walls.

PubMed

Hudak, Paul F

2004-01-01

This study investigated the use of slurry cutoff walls in conjunction with monitoring wells to detect contaminant releases from a solid waste landfill. The 50 m wide by 75 m long landfill was oriented oblique to regional groundwater flow in a shallow sand aquifer. Computer models calculated flow fields and the detection capability of six monitoring networks, four including a 1 m wide by 50 m long cutoff wall at various positions along the landfill's downgradient boundaries and upgradient of the landfill. Wells were positioned to take advantage of convergent flow induced downgradient of the cutoff walls. A five-well network with no cutoff wall detected 81% of contaminant plumes originating within the landfill's footprint before they reached a buffer zone boundary located 50 m from the landfill's downgradient corner. By comparison, detection efficiencies of networks augmented with cutoff walls ranged from 81 to 100%. The most efficient network detected 100% of contaminant releases with four wells, with a centrally located, downgradient cutoff wall. In general, cutoff walls increased detection efficiency by delaying transport of contaminant plumes to the buffer zone boundary, thereby allowing them to increase in size, and by inducing convergent flow at downgradient areas, thereby funneling contaminant plumes toward monitoring wells. However, increases in detection efficiency were too small to offset construction costs for cutoff walls. A 100% detection efficiency was also attained by an eight-well network with no cutoff wall, at approximately one-third the cost of the most efficient wall-augmented network.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Last, G.V.; Eddy, P.A.; Airhart, S.P.

The information presented in this report was collected during limited site investigation activities conducted in the vicinity of Landfills 1 and 4 at Fort Lewis. The purpose of this work was to provide a means of detecting and evaluating the impacts of these inactive landfills on ground-water quality and adjacent lands. This effort included the design and construction of ground-water monitoring systems for compliance with applicable federal and state regulations governing Resource Conservation and Recovery Act (RCRA)-type landfills. Ground-water samples were collected from both existing (1981 and 1984) wells and the newly installed (1988) wells. The analytical results from themore » water samples indicate that the ground water in and around Landfill 1 contains limited contamination. Contaminants may include volatile organic compounds and nitrate. The primary concern in the area around Landfill 1 was the determination that ground water from two wells may contain cis-1,2-dichloroethylene and 1,1,1-trichloroethylene above drinking water standards. Nitrate levels in the downgradient wells were greater than those in upgradient wells and exceeded drinking water standards in some of the less-representative samples. Analyses of ground-water samples from wells in and around Landfill 4 indicate several contaminants may be present. These include volatile organic compounds (principally cis-1,2-dichloroethylene and 1,1,1-trichloroethylene), coliform, oil and grease, and perhaps some metals (iron and magnesium). The primary concern in the area around Landfill 4 was the determination that ground water from five wells contained cis-1,2-dichloroethylene and 1,1,1-trichloroethylene above drinking water standards. The source of contaminants beneath either landfill cannot yet be identified. Insufficient data exist to disprove or confirm either landfill as possible contributors. 19 refs., 32 figs., 17 tabs.« less

Radium mobility and the age of groundwater in public-drinking-water supplies from the Cambrian-Ordovician aquifer system, north-central USA

USGS Publications Warehouse

Stackelberg, Paul E.; Szabo, Zoltan; Jurgens, Bryant C.

2018-01-01

High radium (Ra) concentrations in potable portions of the Cambrian-Ordovician (C-O) aquifer system were investigated using water-quality data and environmental tracers (3H, 3Hetrit, SF6, 14C and 4Herad) of groundwater age from 80 public-supply wells (PSWs). Groundwater ages were estimated by calibration of tracers to lumped parameter models and ranged from modern (<50 yr) in upgradient, regionally unconfined areas to ancient (>1 Myr) in the most downgradient, confined portions of the potable system. More than 80 and 40 percent of mean groundwater ages were older than 1000 and 50,000 yr, respectively. Anoxic, Fe-reducing conditions and increased mineralization develop with time in the aquifer system and mobilize Ra into solution resulting in the frequent occurrence of combined Ra (Rac = 226Ra + 228Ra) at concentrations exceeding the USEPA MCL of 185 mBq/L (5 pCi/L). The distribution of the three Ra isotopes comprising total Ra (Rat = 224Ra + 226Ra + 228Ra) differed across the aquifer system. The concentrations of 224Ra and 228Ra were strongly correlated and comprised a larger proportion of the Rat concentration in samples from the regionally unconfined area, where arkosic sandstones provide an enhanced source for progeny from the 232Th decay series. 226Ra comprised a larger proportion of the Ratconcentration in samples from downgradient confined regions. Concentrations of Rat were significantly greater in samples from the regionally confined area of the aquifer system because of the increase in 226Ra concentrations there as compared to the regionally unconfined area. 226Ra distribution coefficients decreased substantially with anoxic conditions and increasing ionic strength of groundwater (mineralization), indicating that Ra is mobilized to solution from solid phases of the aquifer as adsorption capacity is diminished. The amount of 226Ra released from solid phases by alpha-recoil mechanisms and retained in solution increases relative to the amount of Ra sequestered by adsorption processes or co-precipitation with barite as adsorption capacity and the concentration of Ba decreases. Although 226Ra occurred at concentrations greater than 224Ra or 228Ra, the ingestion exposure risk was greater for 228Ra owing to its greater toxicity. In addition, 224Ra added substantial alpha-particle radioactivity to potable samples from the C-O aquifer system. Thus, monitoring for Ra isotopes and gross-alpha-activity (GAA) is important in upgradient, regionally unconfined areas as downgradient, and GAA measurements made within 72 h of sample collection would best capture alpha-particle radiation from the short-lived 224Ra.

Remedial Investigation Report Area of Contamination (AOC) 43J. Volume 1 of 2

DTIC Science & Technology

1996-02-01

produced risks within the USEPA range (1x1W05 and 3x10’, respectively). If the modified cancer slope factor (CSF) for arsenic was used to estimate excess...lifetime cancer risks for both source area and downgradient groundwater quality, then the cancer risks associated with exposure to both average and...very poorly drained; nearly level, organic; occurs in depressions and on flat areas of uplands and glacial outwash plains. Windsor Series. Deep

Water quality of the Apalachicola-Chattahoochee-Flint and Ocmulgee river basins related to flooding from Tropical Storm Alberto; pesticides in urban and agricultural watersheds, and nitrate and pesticides in ground water, Georgia, Alabama, and Florida

USGS Publications Warehouse

Hippe, D.J.; Wangsness, D.J.; Frick, E.A.; Garrett, J.W.

1994-01-01

This report presents preliminary water-quality information from three studies that are part of the National Water-Quality Assessment (NAWQA) Program in the Apalachicola-Chattahoochee-Flint (ACF) River basin and the adjacent Ocmulgee River basin. During the period July 3-7, 1994, heavy rainfall from tropical storm Alberto caused record flooding on the Ocmulgee and Flint Rivers and several of their tributaries. Much of the nitrogen load transported during the flooding was as organic nitrogen generally derived from organic detritus, rather than nitrate derived from other sources, such as fertilizer. More than half the mean annual loads of total phosphorus and organic nitrogen were trans- ported in the Flint and Ocmulgee Rivers during the flood. Fourteen herbicides, five insecticides, and one fungicide were detected in floodwaters of the Ocmulgee, Flint, and Apalachicola Rivers. In a second study, water samples were collected at nearly weekly intervals from March 1993 through April 1994 from one urban and two agricultural watersheds in the ACF River basin, and analyzed for 84 commonly used pesticides. More pesticides were detected and at generally higher concentrations in water from the urban watershed than the agricultural water- sheds, and a greater number of pesticides were persistent throughout much of the year in the urban watershed. Simazine exceeded U.S. Environmental Protection Agency (EPA) drinking-water standards in one of 57 samples from the urban watershed. In a third study, 38 wells were installed in surficial aquifers adjacent to and downgradient of farm fields within agricultural areas in the southern ACF River basin. Even though regional aquifers are generally used for irrigation and domestic- and public-water supplies, degradation of water quality in the surficial aquifers serves as an early warning of potential contamination of regional aquifers. Nitrate concentrations were less than 3 mg/L as N (indicating minimal effect of human activities) in water from about two-thirds of the wells. Water from the remaining wells had elevated nitrate con- centrations, probably the result of human activity. Nitrate concentrations in two of these wells exceeded EPA drinking-water standards. Water samples from eight wells had pesticide concentrations above method detection limits. With the exception of two samples for shallow ground-water wells and one surface-water sample from the urban watershed, concentrations of nitrate nitrogen and detected pesticides were below EPA standards and guidelines for drinking water. However, concentrations of the insecticides chlorpyrifos, carbaryl, and diazinon in the surface-water samples approached or exceeded guidelines for protection of aquatic life.

Statistical analysis of lake levels and field study of groundwater and surface-water exchanges in the northeast Twin Cities Metropolitan Area, Minnesota, 2002 through 2015: Chapter A of Water levels and groundwater and surface-water exchanges in lakes of the northeast Twin Cities Metropolitan Area, Minnesota, 2002 through 2015

USGS Publications Warehouse

Jones, Perry M.; Trost, Jared J.; Diekoff, Aliesha L.; Rosenberry, Donald O.; White, Eric A.; Erickson, Melinda L.; Morel, Daniel L.; Heck, Jessica M.

2016-10-19

Water levels declined from 2003 to 2011 in many lakes in Ramsey and Washington Counties in the northeast Twin Cities Metropolitan Area, Minnesota; however, water levels in other northeast Twin Cities Metropolitan Area lakes increased during the same period. Groundwater and surface-water exchanges can be important in determining lake levels where these exchanges are an important component of the water budget of a lake. An understanding of groundwater and surface-water exchanges in the northeast Twin Cities Metropolitan Area has been limited by the lack of hydrologic data. The U.S. Geological Survey, in cooperation with the Metropolitan Council and Minnesota Department of Health, completed a field and statistical study assessing lake-water levels and regional and local groundwater and surface-water exchanges near northeast Twin Cities Metropolitan Area lakes. This report documents the analysis of collected hydrologic, water-quality, and geophysical data; and existing hydrologic and geologic data to (1) assess the effect of physical setting and climate on lake-level fluctuations of selected lakes, (2) estimate potential percentages of surface-water contributions to well water across the northeast Twin Cities Metropolitan Area, (3) estimate general ages for waters extracted from the wells, and (4) assess groundwater inflow to lakes and lake-water outflow to aquifers downgradient from White Bear Lake. Statistical analyses of lake levels during short-term (2002–10) and long-term (1925–2014) periods were completed to help understand lake-level changes across the northeast Twin Cities Metropolitan Area. Comparison of 2002–10 lake levels to several landscape and geologic characteristics explained variability in lake-level changes for 96 northeast Twin Cities Metropolitan Area lakes. Application of several statistical methods determined that (1) closed-basin lakes (without an active outlet) had larger lake-level declines than flow-through lakes with an outlet; (2) closed-basin lake-level changes reflected groundwater-level changes in the Quaternary, Prairie du Chien, and Jordan aquifers; (3) the installation of outlet-control structures, such as culverts and weirs, resulted in smaller multiyear lake-level changes than lakes without outlet-control structures; (4) water levels in lakes primarily overlying Superior Lobe deposits were significantly more variable than lakes primarily overlying Des Moines Lobe deposits; (5) lake-level declines were larger with increasing mean lake-level elevation; and (6) the frequency of some of these characteristics varies by landscape position. Flow-through lakes and lakes with outlet-control structures were more common in watersheds with more than 50 percent urban development compared to watersheds with less than 50 percent urban development. A comparison of two 35-year periods during 1925–2014 revealed that variability of annual mean lake levels in flow-through lakes increased when annual precipitation totals were more variable, whereas variability of annual mean lake levels in closed-basin lakes had the opposite pattern, being more variable when annual precipitation totals were less variable. Oxygen-18/oxygen-16 and hydrogen-2/hydrogen-1 ratios for water samples from 40 wells indicated the well water was a mixture of surface water and groundwater in 31 wells, whereas ratios from water sampled from 9 other wells indicated that water from these wells receive no surface-water contribution. Of the 31 wells with a mixture of surface water and groundwater, 11 were downgradient from White Bear Lake, likely receiving water from deeper parts of the lake. Age dating of water samples from wells indicated that the age of water in the Prairie du Chien and Jordan aquifers can vary widely across the northeast Twin Cities Metropolitan Area. Estimated ages of recharge for 9 of the 40 wells sampled for chlorofluorocarbon concentrations ranged widely from the early 1940s to mid-1970s. The wide range in estimated ages of recharge may have resulted from the wide range in the open-interval lengths and depths for the wells.Results from stable isotope analyses of water samples, lake-sediment coring, continuous seismic-reflection profiling, and water-level and flow monitoring indicated that there is groundwater inflow from nearshore sites and lake-water outflow from deep-water sites in White Bear Lake. Continuous seismic-reflection profiling indicated that deep sections of White Bear, Pleasant, Turtle, and Big Marine Lakes have few trapped gases and little organic material, which indicates where groundwater and lake-water exchanges are more likely. Water-level differences between White Bear Lake and piezometer and seepage measurements in deep waters of the lake indicate that groundwater and lake-water exchange is happening in deep waters, predominantly downgradient from the lake and into the lake sediment. Seepage fluxes measured in the nearshore sites of White Bear Lake generally were higher than seepage fluxes measured in the deep-water sites, which indicates that groundwater-inflow rates at most of the nearshore sites are higher than lake-water outflow from the deep-water sites.

Comparison of tracer methods to quantify hydrodynamic exchange within the hyporheic zone

NASA Astrophysics Data System (ADS)

Engelhardt, I.; Piepenbrink, M.; Trauth, N.; Stadler, S.; Kludt, C.; Schulz, M.; Schüth, C.; Ternes, T. A.

2011-03-01

SummaryHydrodynamic exchange between surface-water and groundwater was studied at a river located within the Rhine Valley in Germany. Piezometric pressure heads and environmental tracers such as temperature, stable isotopes, chloride, X-ray contrast media, and artificial sweetener were investigated within the hyporheic zone and river water plume. Vertical profiles of environmental tracers were collected using multi-level wells within the neutral up-gradient zone, beneath the river bed, and within the horizontal proximal and distal down-gradient zone. Infiltration velocities were calculated from pressure heads, temperature fluctuations and gradients. The amount of river water within groundwater was estimated from vertical profiles of chloride, stable isotopes, and persistent pharmaceuticals. Profiles of stable isotopes and chloride reveal the existence of down-welling within the shallow hyporheic zone that is generated by river bed irregularities. Due to down-welling an above-average migration of river water into the hyporheic zone establishes even under upward hydraulic pressure gradients. The investigated environmental tracers could not distinctively display short-time-infiltration velocities representative for flood waves, while average infiltration velocities calculated over several months are uniform displayed. Based on vertical temperature profiles the down-gradient migration of the river water plume could be observed even after long periods of effluent conditions and over a distance of 200 m from the river bank. X-ray contrast media and artificial sweeteners were observed in high concentrations within the proximal zone, but were not detected at a distance of 200 m from the river bank. Using temperature as environmental tracer within the hyporheic zone may result in overestimating the migration of pollutants within the river water plume as the process of natural attenuation will be neglected. Furthermore, temperature was not able to display the effect of down-welling. Stable isotopes and chloride were found to be suitable environmental tracers to forecast the release and fate of organic contaminants within the hyporheic zone.

Progression of natural attenuation processes at a crude-oil spill site . I. Geochemical evolution of the plume

USGS Publications Warehouse

Cozzarelli, I.M.; Bekins, B.A.; Baedecker, M.J.; Aiken, G.R.; Eganhouse, R.P.; Tuccillo, M.E.

2001-01-01

A 16-year study of a hydrocarbon plume shows that the extent of contaminant migration and compound-specific behavior have changed as redox reactions, most notably iron reduction, have progressed over time. Concentration changes at a small scale, determined from analysis of pore-water samples drained from aquifer cores, are compared with concentration changes at the plume scale, determined from analysis of water samples from an observation well network. The small-scale data show clearly that the hydrocarbon plume is growing slowly as sediment iron oxides are depleted. Contaminants, such as ortho-xylene that appeared not to be moving downgradient from the oil on the basis of observation well data, are migrating in thin layers as the aquifer evolves to methanogenic conditions. However, the plume-scale observation well data show that the downgradient extent of the Fe2+ and BTEX plume did not change between 1992 and 1995. Instead, depletion of the unstable Fe (III) oxides near the subsurface crude-oil source has caused the maximum dissolved iron concentration zone within the plume to spread at a rate of approximately 3 m/year. The zone of maximum concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) has also spread within the anoxic plume. In monitoring the remediation of hydrocarbon-contaminated ground water by natural attenuation, subtle concentration changes in observation well data from the anoxic zone may be diagnostic of depletion of the intrinsic electron-accepting capacity of the aquifer. Recognition of these subtle patterns may allow early prediction of growth of the hydrocarbon plume. Copyright ?? 2001 .

Natural attenuation of trichloroethylene in fractured shale bedrock.

PubMed

Lenczewski, M; Jardine, P; McKay, L; Layton, A

2003-07-01

This paper describes one of the first well-documented field examples of natural attenuation of trichloroethylene (TCE) in groundwater in a fractured shale bedrock. The study was carried out adjacent to a former waste burial site in Waste Area Grouping 5 (WAG5) on the Oak Ridge Reservation, Oak Ridge, TN. A contaminant plume containing TCE and its daughter products were detected downgradient from the buried waste pits, with most of the contamination occurring in the upper 6 m of the bedrock. The monitoring well array consists of a 35-m-long transect of multilevel sampling wells, situated along a line between the waste pits and a seep which discharges into a small stream. Concentrations of volatile organic carbons (VOCs) were highest in the waste trenches and decreased with distance downgradient towards the seep. Sampling wells indicated the presence of overlapping plumes of TCE, cis-dichloroethylene (cDCE), vinyl chloride (VC), ethylene, ethane, and methane, with the daughter products extending further downgradient than the parent (TCE). This type of distribution suggests anaerobic biodegradation. Measurements of redox potential at the site indicated that iron-reduction, sulfate reduction, and potentially methanogensis were occurring and are conducive to dechlorination of TCE. Bacteria enrichment of groundwater samples revealed the presence of methanotrophs, methanogens, iron-reducing bacteria and sulfate-reducing bacteria, all of which have previously been implicated in anaerobic biodegradation of TCE. 16S rDNA sequence from DNA extracted from two wells were similar to sequences of organisms previously implicated in the anaerobic biodegradation of chlorinated solvents. The combined data strongly suggest that anaerobic biodegradation of the highly chlorinated compounds is occurring. Aerobic biodegradation may also be occurring in oxygenated zones, including near a seep where groundwater exits the site, or in the upper bedrock during seasonal fluctuations in water table elevation and oxygen levels.

Browns Ferry Nuclear Plant low-level radwaste storage facility ground-water pathway analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boggs, J.M.

1982-10-01

The proposed low-level radwaste storage facility (LLRWSF) at Browns Ferry Nuclear Plant is underlain by soils having low hydraulic conductivity and high sorptive capacity which greatly reduce the risks associated with a potential contaminant excursion. A conservative ground-water pathway accident analysis using flow and solute transport modeling techniques indicates that without interdiction the concentrations of the five radionuclides of concern (Sr-90, Cs-137, Cs-134, Co-60, and Mn-54) would be well below 10 CFR Part 20 criteria at downgradient receptors. These receptors include a possible future private water well located near the eastern site boundary and Wheeler Reservoir. Routine ground-water monitoring ismore » not recommended at the LLRWSF except in the unlikely event of an accident.« less

Hydrogeology and leachate plume delineation at a closed municipal landfill, Norman, Oklahoma

USGS Publications Warehouse

Becker, Carol J.

2002-01-01

The City of Norman operated a solid-waste municipal landfill at two sites on the Canadian River alluvium in Cleveland County, Oklahoma from 1970 to 1985. The sites, referred to as the west and east cells of the landfill, were originally excavations in the unconsolidated alluvial deposits and were not lined. Analysis of ground-water samples indicate that leachate from the west cell is discharging into an adjacent abandoned river channel, referred to as the slough, and is migrating downgradient in ground water toward the Canadian River. The report describes the hydrogeologic features at the landfill, including the topography of the bedrock, water-level changes in the alluvial aquifer, and delineates the leachate plume using specific conductance data. The leading edge of the leachate plume along the 35-80 transect extended over 250 meters downgradient of the west cell. The leading edge of the leachate plume along the 40-SOUTH transect had moved about 60 meters from the west cell in a south-southwesterly direction and had not moved past the slough as of 1997. Specific conductance measurements exceeding 7,000 microsiemens per centimeter at site 40 indicate the most concentrated part of the plume remained in the upper half of the alluvial aquifer adjacent to the west cell. The direction of ground-water flow in the alluvial aquifer surrounding the landfill was generally north-northeast to south-southwest toward the river. However, between the west cell and the slough along the 40-SOUTH transect, head measurements indicate a directional change to the east and southeast toward a channel referred to as the sewage outfall. Near the 35-80 transect, at 0.5 meter below the water table and at the base of the aquifer, the direction of ground-water flow was south-southeast with a gradient of about 30 centimeters per 100 meters. Generally, ground-water levels in the alluvial aquifer were higher during the winter months and lower during summer months, due to a normal decrease in precipitation and increased evapotranspiration in the summer. Hydrographs show temporal water-level changes in ground water and the slough, indicating a hydrologic connection between the alluvial aquifer and the slough.

Denitrification in sediments from the hyporheic zone adjacent to a small forested stream

USGS Publications Warehouse

Duff, J.H.; Triska, F.J.

1990-01-01

Denitrifying potentials increased with increasing distance from the stream channel. Dissolved oxygen was 100% of the concentration expected in equilibrium with the atmosphere in water obtained from monitoring wells immediately adjacent to the stream but was as low as 7% of the expected value in water 11.4 m inland. Both nitrate and dissolved organic carbon decreased over summer in wells at the base of the alder-forested slope. A 48-h injection of nitrate-amended stream water into hyporheic water 8.4 m inland stimulated nitrous oxide production in the presence of acetylene. Nitrous oxide was generated as nitrate and acetylene were co-transported to a well 13 m down-gradient. Acetylene-block experiments coupled with the chemistry data suggest that denitrification can modify the chemistry of water during passage through the hyporheic zone. -from Authors

Chlorine-36 in the Snake River Plain Aquifer at the Idaho National Engineering Laboratory; origin and implications

USGS Publications Warehouse

Beasley, T.M.; Cecil, L.D.; Sharma, P.; Kubik, P.W.; Fehn, U.; Mann, L.J.; Gove, H.E.

1993-01-01

Between 1952 and 1984, low-level radioactive waste was introduced directly into the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL), Idaho Falls, Idaho. These wastes were generated, principally, at the nuclear fuel reprocessing facility on the site. Our measurements of 36C1 in monitoring and production well waters, downgradient from disposal wells and seepage ponds, found easily detectable, nonhazardous concentrations of this radionuclide from the point of injection to the INEL southern site boundary. Comparisons are made between 3H and 36Cl concentrations in aquifer water and the advantages of 36C1 as a tracer of subsurface-water dynamics at the site are discussed.

Waste-indicator and pharmaceutical compounds in landfill-leachate-affected ground water near Elkhart, Indiana, 2000-2002.

PubMed

Buszka, P M; Yeskis, D J; Kolpin, D W; Furlong, E T; Zaugg, S D; Meyer, M T

2009-06-01

Four wells downgradient from a landfill near Elkhart, Indiana were sampled during 2000-2002 to evaluate the presence of waste-indicator and pharmaceutical compounds in landfill-leachate-affected ground water. Compounds detected in leachate-affected ground water included detergent metabolites (p-nonylphenol, nonylphenol monoethoxylate, nonylphenol diethoxylate, and octylphenol monoethoxylate), plasticizers (ethanol-2-butoxy-phosphate and diethylphthalate), a plastic monomer (bisphenol A), disinfectants (1,4-dichlorobenzene and triclosan), an antioxidant (5-methyl-1H-benzotriazole), three fire-retardant compounds (tributylphosphate and tri(2-chloroethyl)phosphate, and tri(dichlorisopropyl)phosphate), and several pharmaceuticals and metabolites (acetaminophen, caffeine, cotinine, 1,7-dimethylxanthine, fluoxetine, and ibuprofen). Acetaminophen, caffeine, and cotinine detections confirm prior indications of pharmaceutical and nicotinate disposal in the landfill.

Effects of land use on quality of water in stratified-drift aquifers in Connecticut

USGS Publications Warehouse

Grady, Stephen J.

1994-01-01

Human activities associated with agricultural, residential, commercial, and industrial land uses have affected the quality of water in the four stratified-drift aquifers examined in Connecticut. A study to evaluate quantitatively the effects of human activities, expressed as land use, on regional ground-water quality was initiated in 1984 as part of the U.S. Geological Survey's Toxic Waste-round-Water Contamination Program. Water-quality data were collected from 116 shallow stainless-steel wells installed beneath or immediately downgradient from seven types of land use areas within the Pootatuck, Pomperaug, Farmington, and Hockanum River valleys in Connecticut. Analysis of variance on the ranked concentrations of 21 largely uncensored or slightly censored constituents, and contingency-table analysis of the frequency of detection of 49 moderately to highly censored constituents indicate that 27 water-quality variables differ at the 0.05 level of significance for samples from at least one land use area. For most constituents, concentrations or detection frequencies are lowest in samples from the undeveloped areas, which characterize background water-quality conditions. The effect of agricultural land use on groundwater quality reflects tillage practices; tilled areas affect the water quality to a greater degree than do untilled areas. Twenty percent of the wells in the tilled agricultural areas yielded water with concentrations of nitrate plus nitrite-nitrogen exceeding 10 milligrams per liter. Atrazine detections in one-third of the wells in areas of tilled agricultural land use were significantly more common than in the undeveloped areas. Ground-water quality beneath sewered residential areas is more severely affected by inorganic and organic nonpoint-source contaminants than is water quality beneath unsewered residential areas. Median concentrations or detection frequencies of most physical properties and inorganic constituents of ground water are higher in sewered than in unsewered residential areas. Generally low concentrations (less than 1.0 microgram per liter) of one or more of 17 volatile organic compounds were detected in samples from 62 percent of the wells in the unsewered residential areas. Most of these compounds were detected in less than 10 percent of the ground-water samples from the unsewered residential areas, however, and consequently, their frequency of detections was not significantly different than in samples from other land use areas. The detection of chloroform in ground-water samples from 47 percent of the wells in the sewered residential areas is significantly higher than the frequency of detection of chloroform in samples from the undeveloped, tilled agricultural, and unsewered residential areas. The quality of ground water is adversely affected beneath commercial areas more so than beneath all other land use areas. Median concentrations of sodium (22.5 milligrams per liter), chloride (36 milligrams per liter), and dissolved solids (286 milligrams per liter) are highest in ground-water samples in commercial areas. Detections of tetrachloroethylene, trichloroethylene, and 1,2-transdichloroethylene were significantly more common in ground-water samples from the commercial areas than in samples from one or more of the other land use areas. Tetrachloroethylene was detected in water samples from 50 percent of the observation wells in the commercial areas at concentrations of up to 1,300 micrograms per liter. Trichloroethylene and 1,2-transdichloroethylene were found at concentrations of up to 20 and 55 micrograms per liter, respectively, in samples from more than 40 percent of the wells in the commercial areas. Although industrial areas occupy only a small part of each of the study areas, they have a disproportionately large effect on ground-water quality. One or more of 12 volatile organic compounds were detected in water samples from 91 percent of the observation wells in the industrial areas

Deterioration of groundwater quality in the vicinity of an active open-tipping site in West Malaysia

NASA Astrophysics Data System (ADS)

Rahim, Bahaa-Eldin E. A.; Yusoff, I.; Samsudin, A. R.; Yaacob, W. Z. W.; Rafek, A. G. M.

2010-06-01

There is an urgent need for characterization of leachate arising from waste disposal to ensure a corresponding effective leachate management policy. Field and laboratory studies have been carried out to investigate the impact of municipal landfill leachate on the underlying groundwater at a site in West Malaysia. The solid waste was disposed of directly onto an unprotected natural soil formation. This situation was made worse by the shallow water table. The hydrochemical composition of groundwater in the vicinity of the site (background) is a dilute mixed cation, bicarbonate water. The high ionic balance error of ~13.5% reveals that the groundwater body underneath the site was a highly contaminated leachate rather than contaminated groundwater. Elevated concentration of chloride (355.48 mg/L), nitrate (10.40 mg/L as NO3), nitrite (14.59 mg/L), ammoniacal-N (11.61 mg/L), sodium (227.56 mg/L), iron (0.97 mg/L), and lead (0.32 mg/L) measured downgradient indicate that the contamination plume has migrated further away from the site. In most cases, the concentration of these contamination indicators, together with the ranges of sodium percentage (66.3-89.9%) and sodium adsorption ratio (10.1-19.7%), were found to be considerably higher than the limit values of safe water for both domestic and irrigation purposes, respectively.

Assessing natural attenuation potential at a uranium (U) in situ recovery site (Rosita, TX, USA) using multiple redox-sensitive isotope systems

NASA Astrophysics Data System (ADS)

Basu, A.; Brown, S. T.; Christensen, J. N.; DePaolo, D. J.; Reimus, P. W.; Heikoop, J. M.; Simmons, A. M.; House, B.; Schilling, K.; Johnson, T. M.; Pelizza, M.

2013-12-01

The In Situ Recovery (ISR) U mining operation at Rosita, TX, USA, involved oxidative dissolution of U from roll front U deposits. This process mobilized U along with other characteristic elements (e.g., Se) from the roll fronts in their soluble and toxic oxidized forms (e.g., U(VI), Se(VI)). The dissolved U(VI) in groundwater poses significant ecological risk due to its chemical toxicity and must be restored below the existing regulatory limit to minimize the environmental impact of ISR mining. However, the undisturbed sediments downgradient to the roll front deposits are expected to remain reduced. Naturally occurring Fe-minerals (e.g., FeS, siderite, magnetite) and microorganisms in the sediments downgradient to ISR activity can reduce dissolved U(VI) to less toxic and insoluble U(IV) and promote natural attenuation. The reduction of oxyanions of U or Se induces measurable isotopic fractionation that can be used to monitor the natural attenuation by downgradient sediments. Here, we used multiple redox-sensitive isotope systems (U, Se, and S) to detect reducing conditions and natural attenuation of U(VI) at the ISR site. We collected groundwater samples from 26 wells located in the ore body, upgradient and downgradient to the ore body. The δ238U values measured in groundwater samples from 23 wells range from 0.48‰ to -1.66‰ (×0.12‰). A preliminary investigation of 6 groundwater samples shows a variation of δ82Se values from -1.44‰ to 5.24‰ (×0.15‰). The δ34SO4 measurements in groundwater vary from 11.8‰ to -19.9‰. The reduction of Se(VI) and SO42- fractionates the lighter isotopes (i.e., 32S and 76Se) in the reduced product phase rendering the remaining reactants in the groundwater enriched in heavier isotopes. Therefore, the high δ82Se and δ34SO4 values may suggest reduction of Se(VI) and SO42-, respectively. The highest δ238U values are observed in the wells located in the ore body or upgradient to the ore body whereas the downgradient wells show significantly lower δ238U values. High δ238U values in most of the wells located in the ore-zone may be attributed to the dissolution of the U ore enriched in 238U. The low δ238U values are generally observed in the wells with low U(VI) concentrations. Since U(VI) reduction fractionates 238U to the solid U(IV) phase, the depletion of 238U in the groundwater samples in the downgradient monitoring wells suggest U(VI) reduction by the downgradient sediments. The δ238U values in the groundwater samples conform to a Rayleigh distillation model with an isotopic fractionation factor α = 1.00013 × 0.00010. Future investigations include characterization of the U ore bearing sediments collected from boreholes in the ore body and downgradient of the ore body, measurement of the δ238U and δ82Se values in the ore and in remaining groundwater samples. The U(VI) reducing capacity and concomitant U isotopic fractionation factors for the sediments from downgradient boreholes will be determined from the batch incubation experiments and flow through column experiments.

Use of a ground-water flow model with particle tracking to evaluate ground-water vulnerability, Clark County, Washington

USGS Publications Warehouse

Snyder, D.T.; Wilkinson, J.M.; Orzol, L.L.

1996-01-01

A ground-water flow model was used in conjunction with particle tracking to evaluate ground-water vulnerability in Clark County, Washington. Using the particle-tracking program, particles were placed in every cell of the flow model (about 60,000 particles) and tracked backwards in time and space upgradient along flow paths to their recharge points. A new computer program was developed that interfaces the results from a particle-tracking program with a geographic information system (GIS). The GIS was used to display and analyze the particle-tracking results. Ground-water vulnerability was evaluated by selecting parts of the ground-water flow system and combining the results with ancillary information stored in the GIS to determine recharge areas, characteristics of recharge areas, downgradient impact of land use at recharge areas, and age of ground water. Maps of the recharge areas for each hydrogeologic unit illustrate the presence of local, intermediate, or regional ground-water flow systems and emphasize the three-dimensional nature of the ground-water flow system in Clark County. Maps of the recharge points for each hydrogeologic unit were overlaid with maps depicting aquifer sensitivity as determined by DRASTIC (a measure of the pollution potential of ground water, based on the intrinsic characteristics of the near-surface unsaturated and saturated zones) and recharge from on-site waste-disposal systems. A large number of recharge areas were identified, particularly in southern Clark County, that have a high aquifer sensitivity, coincide with areas of recharge from on-site waste-disposal systems, or both. Using the GIS, the characteristics of the recharge areas were related to the downgradient parts of the ground-water system that will eventually receive flow that has recharged through these areas. The aquifer sensitivity, as indicated by DRASTIC, of the recharge areas for downgradient parts of the flow system was mapped for each hydrogeologic unit. A number of public-supply wells in Clark County may be receiving a component of water that recharged in areas that are more conducive to contaminant entry. The aquifer sensitivity maps illustrate a critical deficiency in the DRASTIC methodology: the failure to account for the dynamics of the ground-water flow system. DRASTIC indices calculated for a particular location thus do not necessarily reflect the conditions of the ground-water resources at the recharge areas to that particular location. Each hydrogeologic unit was also mapped to highlight those areas that will eventually receive flow from recharge areas with on-site waste-disposal systems. Most public-supply wells in southern Clark County may eventually receive a component of water that was recharged from on-site waste-disposal systems.Traveltimes from particle tracking were used to estimate the minimum and maximum age of ground water within each model-grid cell. Chlorofluorocarbon (CFC)-age dating of ground water from 51 wells was used to calibrate effective porosity values used for the particle- tracking program by comparison of ground-water ages determined through the use of the CFC-age dating with those calculated by the particle- tracking program. There was a 76 percent agreement in predicting the presence of modern water in the 51 wells as determined using CFCs and calculated by the particle-tracking program. Maps showing the age of ground water were prepared for all the hydrogeologic units. Areas with the youngest ground-water ages are expected to be at greatest risk for contamination from anthropogenic sources. Comparison of these maps with maps of public- supply wells in Clark County indicates that most of these wells may withdraw ground water that is, in part, less than 100 years old, and in many instances less than 10 years old. Results of the analysis showed that a single particle-tracking analysis simulating advective transport can be used to evaluate ground-water vulnerability for any part of a ground-wate

A plan for study of hexavalent chromium, CR(VI) in groundwater near a mapped plume, Hinkley, California, 2016

USGS Publications Warehouse

Izbicki, John A.; Groover, Krishangi D.

2016-01-22

The Pacific Gas and Electric Company (PG&E) Hinkley compressor station, in the Mojave Desert 80 miles northeast of Los Angeles, is used to compress natural gas as it is transported through a pipeline from Texas to California. Between 1952 and 1964, cooling water used at the compressor station was treated with a compound containing chromium to prevent corrosion. After cooling, the wastewater was discharged to unlined ponds, resulting in contamination of soil and groundwater in the underlying alluvial aquifer (Lahontan Regional Water Quality Control Board, 2013). Since 1964, cooling-water management practices have been used that do not contribute chromium to groundwater.In 2007, a PG&E study of the natural background concentrations of hexavalent chromium, Cr(VI), in groundwater estimated average concentrations in the Hinkley area to be 1.2 micrograms per liter (μg/L), with a 95-percent upper-confidence limit of 3.1 μg/L (CH2M-Hill, 2007). The 3.1 μg/L upper-confidence limit was adopted by the Lahontan Regional Water Quality Control Board (RWQCB) as the maximum background concentration used to map the plume extent. In response to criticism of the study’s methodology, and an increase in the mapped extent of the plume between 2008 and 2011, the Lahontan RWQCB (Lahontan Regional Water Quality Control Board, 2012) agreed that the 2007 PG&E background-concentration study be updated.The purpose of the updated background study is to evaluate the presence of natural and man-made Cr(VI) near Hinkley, Calif. The study also is to estimate natural background Cr(VI) concentrations in the aquifer upgradient and downgradient from the mapped Cr(VI) contamination plume, as well as in the plume and near its margins. The study was developed by the U.S. Geological Survey (USGS) in collaboration with a technical working group (TWG) composed of community members, the Independent Review Panel (IRP) Manager (Project Navigator, Ltd.), the Lahontan RWQCB, PG&E, and consultants for PG&E.&E.

A Metal Stable Isotope Approach to Understanding Uranium Mobility Across Roll Front Redox Boundaries

NASA Astrophysics Data System (ADS)

Brown, S. T.; Basu, A.; Christensen, J. N.; DePaolo, D. J.; Heikoop, J. M.; Reimus, P. W.; Maher, K.; Weaver, K. L.

2015-12-01

Sedimentary roll-front uranium (U) ore deposits are the principal source of U for nuclear fuel in the USA and an important part of the current all-of-the-above energy strategy. Mining of roll-front U ore in the USA is primarily by in situ alkaline oxidative dissolution of U minerals. There are significant environmental benefits to in situ mining including no mine tailings or radioactive dust, however, the long-term immobilization of U in the aquifer after the completion of mining remains uncertain. We have utilized the metal stable isotopes U, Se and Mo in groundwater from roll-front mines in Texas and Wyoming to quantify the aquifer redox conditions and predict the onset of U reduction after post mining aquifer restoration. Supporting information from the geochemistry of groundwater and aquifer sediments are used to understand the transport of U prior to and after in situ mining. Groundwater was collected across 4 mining units at the Rosita mine in the Texas coastal plain and 2 mining units at the Smith Ranch mine in the Powder River Basin, Wyoming. In general, the sampled waters are moderately reducing and ore zone wells contain the highest aqueous U concentrations. The lowest U concentrations occur in monitoring wells downgradient of the ore zone. 238U/235U is lowest in downgradient wells and is correlated with aqueous U concentrations. Rayleigh distillation models of the 238U/235U are consistent with U isotope fractionation factors of 1.0004-1.001, similar to lab-based studies. Based on these results we conclude that redox reactions continue to affect U distribution in the ore zone and downgradient regions. We also measured aqueous selenium isotope (δ82Se) and molybdenum isotope (δ98Mo) compositions in the Rosita groundwater. Se(VI) primarily occurs in the upgradient wells and is absent in most ore zone and downgradient wells. Rayleigh distillation models suggest reduction of Se(VI) along the groundwater flow path and when superimposed on the U isotope data Se reduction is favored over U reduction. The δ98Mo of Rosita groundwater is significantly elevated compared to the U ore and is negatively correlated with the groundwater Eh, which suggests localized strong reducing conditions capable of Mo reduction. Ongoing work will determine the Mo isotope systematics of U ores and groundwater from roll-front deposits.

Water levels and groundwater and surface-water exchanges in lakes of the northeast Twin Cities Metropolitan Area, Minnesota, 2002 through 2015

USGS Publications Warehouse

Jones, Perry M.; Trost, Jared J.; Erickson, Melinda L.

2016-10-19

OverviewThis study assessed lake-water levels and regional and local groundwater and surface-water exchanges near northeast Twin Cities Metropolitan Area lakes applying three approaches: statistical analysis, field study, and groundwater-flow modeling.  Statistical analyses of lake levels were completed to assess the effect of physical setting and climate on lake-level fluctuations of selected lakes. A field study of groundwater and surface-water interactions in selected lakes was completed to (1) estimate potential percentages of surface-water contributions to well water across the northeast Twin Cities Metropolitan Area, (2) estimate general ages for waters extracted from the wells, and (3) assess groundwater inflow to lakes and lake-water outflow to aquifers downgradient from White Bear Lake.  Groundwater flow was simulated using a steady-state, groundwater-flow model to assess regional groundwater and surface-water exchanges and the effects of groundwater withdrawals, climate, and other factors on water levels of northeast Twin Cities Metropolitan Area lakes.

Groundwater resources of the East Mountain area, Bernalillo, Sandoval, Santa Fe, and Torrance Counties, New Mexico, 2005

USGS Publications Warehouse

Bartolino, James R.; Anderholm, Scott K.; Myers, Nathan C.

2010-01-01

The groundwater resources of about 400 square miles of the East Mountain area of Bernalillo, Sandoval, Santa Fe, and Torrance Counties in central New Mexico were evaluated by using groundwater levels and water-quality analyses, and updated geologic mapping. Substantial development in the study area (population increased by 11,000, or 50 percent, from 1990 through 2000) has raised concerns about the effects of growth on water resources. The last comprehensive examination of the water resources of the study area was done in 1980-this study examines a slightly different area and incorporates data collected in the intervening 25 years. The East Mountain area is geologically and hydrologically complex-in addition to the geologic units, such features as the Sandia Mountains, Tijeras and Gutierrez Faults, Tijeras syncline and anticline, and the Estancia Basin affect the movement, availability, and water quality of the groundwater system. The stratigraphic units were separated into eight hydrostratigraphic units, each having distinct hydraulic and chemical properties. Overall, the major hydrostratigraphic units are the Madera-Sandia and Abo-Yeso; however, other units are the primary source of supply in some areas. Despite the eight previously defined hydrostratigraphic units, water-level contours were drawn on the generalized regional potentiometric map assuming all hydrostratigraphic units are connected and function as a single aquifer system. Groundwater originates as infiltration of precipitation in upland areas (Sandia, Manzano, and Manzanita Mountains, and the Ortiz Porphyry Belt) and moves downgradient into the Tijeras Graben, Tijeras Canyon, San Pedro synclinorium, and the Hagan, Estancia, and Espanola Basins. The study area was divided into eight groundwater areas defined on the basis of geologic, hydrologic, and geochemical information-Tijeras Canyon, Cedar Crest, Tijeras Graben, Estancia Basin, San Pedro Creek, Ortiz Porphyry Belt, Hagan Basin, and Upper Sandia Mountains. View report for unabridged abstract.

Geohydrology and water quality of Marine Corps Logistics Base, Nebo and Yermo annexes, near Barstow, California

USGS Publications Warehouse

Densmore, Jill N.; Cox, Brett F.; Crawford, Steven M.

1997-01-01

Because ground water is the only dependable source of water in the Barstow area, a thorough understanding of the relationship between the geology and hydrology of this area is needed to make informed ground-water management andremediation decisions. This report summarizes geologic and hydrologic studies done during 1992-95 at the Marine Corps Logistics Base, Nebo and Yermo Annexes, near Barstow, California. The geologic investigation dealt with the stratigraphy and geologic history of the area and determined the location of faults that cross the Marine Corps Logistics Base, Nebo Annex. Two of these faultscoincide with significant ground-water barriers. Geologic and hydrologic data collected for this study were used to define two main aquifer systems in this area. The Mojave River aquifer is contained within the sand and gravel of the Mojave River alluvium, and the regional aquifer lies in the bordering alluvial-fan deposits and older alluvium. Water-level data showed that recharge occurs exten sively in the Mojave River aquifer but occurs only in small areas of the regional aquifer. Dissolved- solids concentrations showed that ground-water degradation exists in the Mojave River aquifer near the Nebo Annex and extends at least 1 mile downgradient of the Nebo golf course in the younger Mojave River alluvium. Nitrogen concentrations show that more than one source is causing the observed degradation in the Mojave River aquifer. Oxygen-18, deuterium, tritium, andcarbon-14 data indicate that the Mojave River and regional aquifers have different sources of recharge and that recent recharge occurs in the Mojave River aquifer but is more limited in the regional aquifer.

Patterns of entrapped air dissolution in a two-dimensional pilot-scale synthetic aquifer.

PubMed

McLeod, Heather C; Roy, James W; Smith, James E

2015-01-01

Past studies of entrapped air dissolution have focused on one-dimensional laboratory columns. Here the multidimensional nature of entrapped air dissolution was investigated using an indoor tank (180 × 240 × 600 cm(3) ) simulating an unconfined sand aquifer with horizontal flow. Time domain reflectometry (TDR) probes directly measured entrapped air contents, while dissolved gas conditions were monitored with total dissolved gas pressure (PTDG ) probes. Dissolution occurred as a diffuse wedge-shaped front from the inlet downgradient, with preferential dissolution at depth. This pattern was mainly attributed to increased gas solubility, as shown by PTDG measurements. However, compression of entrapped air at greater depths, captured by TDR and leading to lower quasi-saturated hydraulic conductivities and thus greater velocities, also played a small role. Linear propagation of the dissolution front downgradient was observed at each depth, with both TDR and PTDG , with increasing rates with depth (e.g, 4.1 to 5.7× slower at 15 cm vs. 165 cm depth). PTDG values revealed equilibrium with the entrapped gas initially, being higher at greater depth and fluctuating with the barometric pressure, before declining concurrently with entrapped air contents to the lower PTDG of the source water. The observed dissolution pattern has long-term implications for a wide variety of groundwater management issues, from recharge to contaminant transport and remediation strategies, due to the persistence of entrapped air near the water table (potential timescale of years). This study also demonstrated the utility of PTDG probes for simple in situ measurements to detect entrapped air and monitor its dissolution. © 2014 Her Majesty the Queen in Right of Canada Groundwater © 2014, National Ground Water Association.

2011 Mound Site Groundwater Plume Rebound Exercise and Follow-Up - 13440

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooten, Gwendolyn; Cato, Rebecca; Lupton, Greg

2013-07-01

The Mound Site facility near Miamisburg, Ohio, opened in 1948 to support early atomic weapons programs. It grew into a research, development, and production facility performing work in support of the U.S. Department of Energy (DOE) weapons and energy programs. The plant was in operation until 1995. During the course of operation, an onsite landfill was created. The landfill was located over a finger of a buried valley aquifer, which is a sole drinking water source for much of the Miami Valley. In the 1980's, volatile organic compounds (VOCs) were discovered in groundwater at the Mound site. The site wasmore » placed on the National Priorities List on November 21, 1989. DOE signed a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Federal Facility Agreement with the U.S. Environmental Protection Agency (EPA) and the Ohio Environmental Protection Agency. The agreement became effective in October 1990. The area that included the landfill was designated Operational Unit 1 (OU-1). In 1995, a Record of Decision was signed that called for the installation and operation of a pump and treatment (P and T) system in order to prevent the VOCs in OU-1 groundwater from being captured by the onsite water production wells. In addition to the P and T system, a soil vapor extraction (SVE) system was installed in 1997 to accelerate removal of VOCs from groundwater in the OU-1 area. The SVE system was successful in removing large amounts of VOCs and continued to operate until 2007, when the amount of VOCs removed became minimal. A rebound study was started in February 2003 to determine how the groundwater system and contaminants would respond to shutting down the P and T system. The rebound test was stopped in February 2004 because predetermined VOC threshold concentrations were exceeded down-gradient of the landfill. The P and T and SVE systems were restarted after the termination of the rebound test. In 2006, the remediation of the Mound site was completed and the site was declared to be protective of human health and the environment, as long as the institutional controls are observed. The institutional controls that apply to the OU-1 area include provisions that no soil be allowed to leave the site, no wells be installed for drinking water, and the site may be approved only for industrial use. The onsite landfill with the operating CERCLA remedy remained. However, the Mound Development Corporation lobbied Congress for funds to remediate the remaining onsite landfill to allow for property reuse. In 2007 DOE received funding from Congress to perform non-CERCLA removal actions at OU-1 to excavate the site sanitary landfill. In 2009, DOE received American Recovery and Reinvestment Act funding to complete the project. Excavation of the landfill occurred intermittently from 2006 through 2010 and the majority of the VOC source was removed; however, VOC levels near the P and T system remained greater than the EPA maximum contaminant levels (MCLs). Presently, groundwater is contained using two extraction wells to create a hydraulic barrier to prevent down-gradient migration of VOC-impacted groundwater. Since the primary contamination source has been removed, the feasibility of moving away from containment to a more passive remedy, namely monitored natural attenuation (MNA), is being considered. A second rebound study was started in June 2011. If contaminant and groundwater behavior met specific conditions during the study, MNA would be evaluated and considered as a viable alternative for the groundwater in the OU-1 area. From June through December 2011, the second rebound study evaluated the changes in VOC concentrations in groundwater when the P and T system was not in operation. As the study progressed, elevated concentrations of VOCs that exceeded predetermined trigger values were measured along the down-gradient boundary of the study area, and so the P and T system was restarted. It was determined that a discrete area with VOC concentrations greater than the MCLs was present in groundwater down-gradient of the extraction wells. The source was not identified, but the contamination was thought not to be caused by residually contaminated soil beneath the former landfill. The data collected so far supports the consideration of MNA as a viable alternative to hydraulic containment. Additional investigations are being performed to identify possible sources or pathways of VOCs in groundwater that may be contributing to the elevated VOC levels measured down-gradient of the extraction well system. Data from this additional investigation will be used to determine whether the VOCs detected down-gradient of the hydraulic boundary are the result of residual soil contamination, a previously unknown contribution of VOC-contaminated water entering the groundwater outside the capture zone of the extraction wells, or a pulse of VOC-contaminated groundwater from the OU-1 landfill that occurred during the rebound study. (authors)« less

Superfund Record of Decision (EPA Region 4): Milan Army Ammunition Plant, TN. (First remedial action), September 1992. Interim report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-09-30

The 22,436-acre Milan Army Ammunition Plant (MAAP) is located in western Tennessee, 5 miles east of Milan, Tennessee. The facility was constructed in 1941 to produce and store fuses, boosters, and small- and large-caliber ammunition. The ROD addresses an interim remedy for the contaminated ground water beneath and immediately downgradient from the former ponds as OU1. The primary contaminants of concern affecting the ground water are VOCs, including carbon disulfide; other organics, including HMX, RDX, 2,4,6-TNT, 2,4-DNT, 2,6-DNT, 1,3-DNB, 1,3,5-trinitrobenzene, and nitrobenzene; and inorganics, including nitrate.

Waste-indicator and pharmaceutical compounds in landfill-leachate-affected ground water near Elkhart, Indiana, 2000-2002

USGS Publications Warehouse

Buszka, P.M.; Yeskis, D.J.; Kolpin, D.W.; Furlong, E.T.; Zaugg, S.D.; Meyer, M.T.

2009-01-01

Four wells downgradient from a landfill near Elkhart, Indiana were sampled during 2000-2002 to evaluate the presence of waste-indicator and pharmaceutical compounds in landfill-leachate-affected ground water. Compounds detected in leachate-affected ground water included detergent metabolites (p-nonylphenol, nonylphenol monoethoxylate, nonylphenol diethoxylate, and octylphenol monoethoxylate), plasticizers (ethanol-2-butoxy-phosphate and diethylphthalate), a plastic monomer (bisphenol A), disinfectants (1,4-dichlorobenzene and triclosan), an antioxidant (5-methyl-1H-benzotriazole), three fire-retardant compounds (tributylphosphate and tri(2-chloroethyl)phosphate, and tri(dichlorisopropyl)phosphate), and several pharmaceuticals and metabolites (acetaminophen, caffeine, cotinine, 1,7-dimethylxanthine, fluoxetine, and ibuprofen). Acetaminophen, caffeine, and cotinine detections confirm prior indications of pharmaceutical and nicotinate disposal in the landfill. ?? 2009 Springer Science + Business Media, LLC.

Steady-State and Transient Groundwater Flow and Advective Transport, Eastern Snake River Plain Aquifer, Idaho National Laboratory and Vicinity, Idaho

NASA Astrophysics Data System (ADS)

Fisher, J. C.; Ackerman, D. J.; Rousseau, J. P.; Rattray, G. W.

2009-12-01

Three-dimensional steady-state and transient models of groundwater flow and advective transport through the fractured basalts and interbedded sediments of the Eastern Snake River Plain (ESRP) aquifer were developed by the U.S. Geological Survey in cooperation with the U.S. Department of Energy. The model domain covers an area of 1,940 square miles that includes most of the Idaho National Laboratory (INL). A 50-year history of waste disposal at the INL has resulted in measurable concentrations of waste contaminants in the aquifer. Numerical models simulated 1980 steady-state conditions and transient flow for 1980-95. In the transient model, streamflow infiltration was the major stress. The models were calibrated using the parameter-estimation program incorporated in MODFLOW-2000. The steady-state model reasonably simulated the observed water-table altitude and gradients. Simulation of transient conditions reproduced changes in the flow system resulting from episodic infiltration from the Big Lost River. Analysis of simulations shows that flow is (1) dominantly horizontal through interflow zones in basalt, vertical anisotropy resulting from contrasts in hydraulic conductivity of different types of basalt and the interbedded sediments, (2) temporally variable due to streamflow infiltration from the Big Lost River, and (3) moving downward downgradient of the INL. Particle-tracking simulations were used to evaluate how simulated groundwater flow paths and travel times differ between the steady-state and transient flow models, and how well model-derived groundwater flow directions and velocities compare to independently-derived estimates. Particle tracking also was used to simulate the growth of tritium plumes originating at two INL facilities over a 16 year period under steady-state and transient flow conditions (1953-68). The shape, dimensions, and areal extent of these plumes were compared to a map of the plumes for 1968 from tritium releases beginning in 1952. Collectively, the particle-tracking simulations indicate that groundwater flow paths and velocities, based on uncalibrated estimates of porosity, are influenced by the dynamic character of the water table and the large contrasts in the hydraulic properties of the media, primarily hydraulic conductivity. Simulation results also indicate that temporal changes in the local hydraulic gradient can account for some of the observed dispersion of contaminants in the aquifer near the major sources of contamination and perhaps the majority of the observed dispersion several miles downgradient of these facilities. The distance downgradient of the facilities where simulated particle plumes were able to reasonably reproduce the 1968 tritium plume extended only to the boundary separating sediment-rich from sediment-poor aquifer layers about 4 mi downgradient of the contaminant source. Particle plumes simulated beyond this boundary were narrow and long, and did not reasonably reproduce the shape, dimensions, or position of the leading edge of the tritium plume; however, few data were available to characterize its true areal extent and shape.

Assessment of natural attenuation of ground-water contamination at sites FT03, LF13, and WP14/LF15, Dover Air Force Base, Delaware

USGS Publications Warehouse

Barbaro, Jeffrey R.

2002-01-01

Water-quality, aquifer-sediment, and hydro-logic data were used to assess the effectiveness of natural attenuation of ground-water contamination at Fire Training Area Three, the Rubble Area Landfill, the Liquid Waste Disposal Landfill, and the Receiver Station Landfill in the East Management Unit of Dover Air Force Base, Delaware. These sites, which are contaminated with chlorinated solvents and fuel hydrocarbons, are under-going long-term monitoring to determine if natural attenuation continues to sufficiently reduce contaminant concentrations to meet regulatory requirements. This report is the first assessment of the effectiveness of natural attenuation at these sites since long-term monitoring began in 1999, and follows a preliminary investigation done in 1995?96. This assessment was done by the U.S. Geological Survey in cooperation with the U.S. Air Force.Since 1995?96, additional information has been collected and used in the current assessment. The conclusions in this report are based primarily on ground-water samples collected from January through March 2000. Previous analytical results from selected wells, available geologic and geo-physical well logs, and newly acquired information such as sediment organic-carbon measurements, hydraulic-conductivity measurements determined from slug tests on wells in the natural attenuation study area, and water-level measurements from surficial-aquifer wells also were used in this assessment. This information was used to: (1) calculate retardation factors and estimate contaminant migration velocities, (2) improve estimates of ground-water flow directions and inferred contaminant migration pathways, (3) better define the areal extent of contamination and the proximity of contaminants to discharge areas and the Base boundary, (4) develop a better under-standing of the vertical variability of contaminant concentrations and redox conditions, (5) evaluate the effects of temporal changes on concentrations in the plumes and source areas, and (6) determine whether intrinsic biodegradation is occurring at these sites.The water-quality data indicate that intrinsic biodegradation is occurring at all three sites. The strongest indication of intrinsic biodegradation is the detection of tetrachloroethene and trichloroethene breakdown products within and down-gradient of the source areas. The patterns of electron acceptors and metabolic by-products indicate that contaminant biodegradation has changed the prevailing geochemistry of the surficial aquifer, creating the strongly reducing conditions necessary for chlorinated solvent bio-degradation. Geochemical changes include depleted dissolved oxygen and elevated ferrous iron and methane levels relative to concentrations in uncontaminated zones of the surficial aquifer. At Fire Training Area Three and the Rubble Area Landfill sites, natural attenuation appears to be adequate for controlling the migration of the contaminant plumes. At the third site, the Liquid Waste Disposal and Receiver Station Landfills, the plume is larger and the uncertainty about the effectiveness of natural attenuation in reducing contaminant concentrations and controlling plume migration is greater. Ground-water data indicate, however, that U.S. Environmental Protection Agency maximum contaminant levels were not exceeded in any point-of-compliance wells located along the Base boundary.The information presented in this report led to the development of improved conceptual models for these sites, and to the recognition of four issues that are currently unclear and may need further study. These issues include delineating the areal and vertical extent of the contaminant plumes in greater detail, determining the extent of intrinsic biodegradation downgradient of the Liquid Waste Disposal and Receiver Station Landfills, deter-mining the fate of contaminants in the ground-water discharge areas, and determining the effect of temporal variability in source concentrations and ground-water

Water Quality in the Equus Beds Aquifer and the Little Arkansas River Before Implementation of Large-Scale Artificial Recharge, South-Central Kansas, 1995-2005

USGS Publications Warehouse

Ziegler, Andrew C.; Hansen, Cristi V.; Finn, Daniel A.

2010-01-01

Artificial recharge of the Equus Beds aquifer using runoff from the Little Arkansas River in south-central Kansas was first proposed in 1956 and was one of many options considered by the city of Wichita to preserve its water supply. Declining aquifer water levels of as much as 50 feet exacerbated concerns about future water availability and enhanced migration of saltwater into the aquifer from past oil and gas activities near Burrton and from the Arkansas River. Because Wichita changed water-management strategies and decreased pumping from the Equus Beds aquifer in 1992, water storage in the aquifer recovered by about 50 percent. This recovery is the result of increased reliance on Cheney Reservoir for Wichita water supply, decreased aquifer pumping, and larger than normal precipitation. Accompanying the water-level recovery, the average water-level gradient in the aquifer decreased from about 12 feet per mile in 1992 to about 8 feet per mile in January 2006. An important component of artificial recharge is the water quality of the receiving aquifer and the water being recharged (source water). Water quality within the Little Arkansas River was defined using data from two real-time surface-water-quality sites and discrete samples. Water quality in the Equus Beds aquifer was defined using sample analyses collected at 38 index sites, each with a well completed in the shallow and deep parts of the Equus Beds aquifer. In addition, data were collected at diversion well sites, recharge sites, background wells, and prototype wells for the aquifer storage and recovery project. Samples were analyzed for major ions, nutrients, trace metals, radionuclides, organic compounds, and bacterial and viral indicators. Water-quality constituents of concern for artificial recharge are those constituents that frequently (more than 5 percent of samples) may exceed Federal [U.S. Environmental Protection Agency (USEPA)] and State drinking-water criteria in water samples from the receiving aquifer or in samples from the source water. Constituents of concern include major ions (sulfate and chloride), nutrients (nitrite plus nitrate), trace elements (arsenic, iron, and manganese), organic compounds (atrazine), and fecal bacterial indicators. This report describes the water quality in the Equus Beds aquifer and the Little Arkansas River from 1995 through 2005 before implementation of large-scale recharge activities. Sulfate concentrations in water samples from the Little Arkansas River rarely exceeded Federal secondary drinking water regulation (SDWR) of 250 milligrams per liter (mg/L). Sulfate concentrations in groundwater were exceeded in about 18 percent of the wells in the shallow (less than or equal to 80 feet deep) parts of the aquifer and in about 13 percent of the wells in the deep parts the aquifer. Larger sulfate concentrations were associated with parts of the aquifer with the largest water-level declines. Water-quality changes in the Equus Beds aquifer likely were caused by dewatering and oxidation of aquifer material that subsequently resulted in increased sulfate concentrations as water levels recovered. The primary sources of chloride to the Equus Beds aquifer are from past oil and gas activities near Burrton and from the Arkansas River. Computed chloride concentrations in the Little Arkansas River near Halstead exceeded the Federal SDWR of 250 mg/L about 27 percent of the time (primarily during low-flow conditions). Chloride concentrations in groundwater exceeded 250 mg/L in about 8 percent or less of the study area, primarily near Burrton and along the Arkansas River. Chloride in groundwater near Burrton has migrated downgradient about 3 miles during the past 40 to 45 years. The downward and horizontal migration of the chloride is controlled by the hydraulic gradient in the aquifer, dispersion of chloride, and discontinuous clay layers that can inhibit further downward migration. Chloride in the shallow parts of the Equus Beds

Dissolved Organic Carbon 14C in Southern Nevada Groundwater and Implications for Groundwater Travel Times

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hershey, Ronald L.; Fereday, Wyall; Thomas, James M

Dissolved inorganic carbon (DIC) carbon-14 ( 14C) ages must be corrected for complex chemical and physical reactions and processes that change the amount of 14C in groundwater as it flows from recharge to downgradient areas. Because of these reactions, DIC 14C can produce unrealistically old ages and long groundwater travel times that may, or may not, agree with travel times estimated by other methods. Dissolved organic carbon (DOC) 14C ages are often younger than DIC 14C ages because there are few chemical reactions or physical processes that change the amount of DOC 14C in groundwater. However, there are several issuesmore » that create uncertainty in DOC 14C groundwater ages including limited knowledge of the initial (A 0) DOC 14C in groundwater recharge and potential changes in DOC composition as water moves through an aquifer. This study examines these issues by quantifying A 0 DOC 14C in recharge areas of southern Nevada groundwater flow systems and by evaluating changes in DOC composition as water flows from recharge areas to downgradient areas. The effect of these processes on DOC 14C groundwater ages is evaluated and DOC and DIC 14C ages are then compared along several southern Nevada groundwater flow paths. Twenty-seven groundwater samples were collected from springs and wells in southern Nevada in upgradient, midgradient, and downgradient locations. DOC 14C for upgradient samples ranged from 96 to 120 percent modern carbon (pmc) with an average of 106 pmc, verifying modern DOC 14C ages in recharge areas, which decreases uncertainty in DOC 14C A 0 values, groundwater ages, and travel times. The HPLC spectra of groundwater along a flow path in the Spring Mountains show the same general pattern indicating that the DOC compound composition does not change along this flow path. Although DOC concentration decreases from recharge-area to downgradient groundwater, the organic compounds are similar, indicating that DOC 14C is unaffected by other processes such as microbial degradation. A small amount of organic carbon was leached from crushed volcanic and carbonate aquifer outcrop rock in rock-leaching experiments. The leached DOC was high in 14C (75 pmc carbonate rocks, 91 pmc volcanic) suggesting that the leached DOC likely came from microbes in the rock samples. The small amount of DOC and high 14C indicates that the amount of old organic carbon in these rocks is low so there should be minimal impact on groundwater DOC 14C ages. Based on the results from this study, DOC 14C ages do not require additional corrections. Several correction models were applied to DIC 14C ages to correct for water-rock reactions along two carbonate and two volcanic flow paths and the corresponding travel times were compare to DOC 14C travel times. The DOC 14C travel times were hundreds to thousands of years shorter than uncorrected and corrected DIC 14C travel times except for the upper section of one carbonate flow path. DOC 14C travel times ranged from 400 to 5,400 years as compared to DIC 14C that ranged from modern to 20,900 years. The DIC 14C ages are greatly influenced by carbonate mineral and gas reactions and other processes such as matrix diffusion, isotope exchange, or adsorption, which are not always adequately accounted for in DIC 14C groundwater age correction models.« less

Assessment of regional change in nitrate concentrations in groundwater in the Central Valley, California, USA, 1950s-2000s

USGS Publications Warehouse

Burow, Karen R.; Jurgens, Bryant C.; Belitz, Kenneth; Dubrovsky, Neil M.

2013-01-01

A regional assessment of multi-decadal changes in nitrate concentrations was done using historical data and a spatially stratified non-biased approach. Data were stratified into physiographic subregions on the basis of geomorphology and soils data to represent zones of historical recharge and discharge patterns in the basin. Data were also stratified by depth to represent a shallow zone generally representing domestic drinking-water supplies and a deep zone generally representing public drinking-water supplies. These stratifications were designed to characterize the regional extent of groundwater with common redox and age characteristics, two factors expected to influence changes in nitrate concentrations over time. Overall, increasing trends in nitrate concentrations and the proportion of nitrate concentrations above 5 mg/L were observed in the east fans subregion of the Central Valley. Whereas the west fans subregion has elevated nitrate concentrations, temporal trends were not detected, likely due to the heterogeneous nature of the water quality in this area and geologic sources of nitrate, combined with sparse and uneven data coverage. Generally low nitrate concentrations in the basin subregion are consistent with reduced geochemical conditions resulting from low permeability soils and higher organic content, reflecting the distal portions of alluvial fans and historical groundwater discharge areas. Very small increases in the shallow aquifer in the basin subregion may reflect downgradient movement of high nitrate groundwater from adjacent areas or overlying intensive agricultural inputs. Because of the general lack of regionally extensive long-term monitoring networks, the results from this study highlight the importance of placing studies of trends in water quality into regional context. Earlier work concluded that nitrate concentrations were steadily increasing over time in the eastern San Joaquin Valley, but clearly those trends do not apply to other physiographic subregions within the Central Valley, even where land use and climate are similar.

Source, Distribution, and Management of Arsenic in Water from Wells, Eastern San Joaquin Ground-Water Subbasin, California

USGS Publications Warehouse

Izbicki, John A.; Stamos, Christina L.; Metzger, Loren F.; Halford, Keith J.; Kulp, Thomas R.; Bennett, George L.

2008-01-01

Between 1974 and 2001 water from as many as one-third of wells in the Eastern San Joaquin Ground Water Subbasin, about 80 miles east of San Francisco, had arsenic concentrations greater than the U.S. Environmental Protection Agency Maximum Contaminant Level (MCL) for arsenic of 10 micrograms per liter (ug/L). Water from some wells had arsenic concentrations greater than 60 ug/L. The sources of arsenic in the study area include (1) weathering of arsenic bearing minerals, (2) desorption of arsenic associated with iron and manganese oxide coatings on the surfaces of mineral grains at pH's greater than 7.6, and (3) release of arsenic through reductive dissolution of iron and manganese oxide coatings in the absence of oxygen. Reductive dissolution is responsible for arsenic concentrations greater than the MCL. The distribution of arsenic varied areally and with depth. Concentrations were lower near ground-water recharge areas along the foothills of the Sierra Nevada; whereas, concentrations were higher in deeper wells at the downgradient end of long flow paths near the margin of the San Joaquin Delta (fig. 1). Management opportunities to control high arsenic concentrations are present because water from the surface discharge of wells is a mixture of water from the different depths penetrated by wells. On the basis of well-bore flow and depth-dependent water-quality data collected as part of this study, the screened interval of a public-supply well having arsenic concentrations that occasionally exceed the MCL was modified to reduce arsenic concentrations in the surface discharge of the well. Arsenic concentrations from the modified well were about 7 ug/L. Simulations of ground-water flow to the well showed that although upward movement of high-arsenic water from depth within the aquifer occurred, arsenic concentrations from the well are expected to remain below the MCL.

Surface-Water and Ground-Water Interactions in the Central Everglades, Florida

USGS Publications Warehouse

Harvey, Judson W.; Newlin, Jessica T.; Krest, James M.; Choi, Jungyill; Nemeth, Eric A.; Krupa, Steven L.

2004-01-01

Recharge and discharge are hydrological processes that cause Everglades surface water to be exchanged for subsurface water in the peat soil and the underlying sand and limestone aquifer. These interactions are thought to be important to water budgets, water quality, and ecology in the Everglades. Nonetheless, relatively few studies of surface water and ground water interactions have been conducted in the Everglades, especially in its vast interior areas. This report is a product of a cooperative investigation conducted by the USGS and the South Florida Water Management District (SFWMD) aimed at developing and testing techniques that would provide reliable estimates of recharge and discharge in interior areas of WCA-2A (Water Conservation Area 2A) and several other sites in the central Everglades. The new techniques quantified flow from surface water to the subsurface (recharge) and the opposite (discharge) using (1) Darcy-flux calculations based on measured vertical gradients in hydraulic head and hydraulic conductivity of peat; (2) modeling transport through peat and decay of the naturally occurring isotopes 224Ra and 223Ra (with half-lives of 4 and 11 days, respectively); and (3) modeling transport and decay of naturally occurring and 'bomb-pulse' tritium (half-life of 12.4 years) in ground water. Advantages and disadvantages of each method for quantifying recharge and discharge were compared. In addition, spatial and temporal variability of recharge and discharge were evaluated and controlling factors identified. A final goal was to develop appropriately simplified (that is, time averaged) expressions of the results that will be useful in addressing a broad range of hydrological and ecological problems in the Everglades. Results were compared with existing information about water budgets from the South Florida Water Management Model (SFWMM), a principal tool used by the South Florida Water Management District to plan many of the hydrological aspects of the Everglades restoration. A century of water management for flood control and water storage in the Everglades resulted in the creation of the Water Conservation Areas (WCAs). Construction of the major canals began in the 1910s and the systems of levees that enclose the basins and structures that move water between basins were largely completed by the 1950s. The abandoned wetlands that remained outside of the Water Conservation areas tended to dry out and subside by 10 feet or more, which created abrupt transitions in land-surface elevations and water levels across the levees. The increases in topographic and hydraulic gradients near the margins of the WCAs, along with rapid pumping of water between basins to achieve management objectives, have together altered the patterns of recharge and discharge in the Everglades. The most evident change is the increase in the magnitude of recharge (on the upgradient side) and discharge (on the downgradient side) of levees separating WCA-2A from other basins or areas outside. Recharge and discharge in the vast interior of WCA-2A also likely have increased, but fluxes in the interior wetlands are more subtle and more difficult to quantify compared with areas close to the levees. Surface-water and ground-water interactions differ in fundamental ways between wetlands near WCA-2A's boundaries and wetlands in the basin's interior. The levees that form the WCA's boundaries have introduced step functions in the topographic and hydraulic gradients that are important as a force to drive water flow across the wetland ground surface. The resulting recharge and discharge fluxes tend to be unidirectional (connecting points of recharge on the upgradient side of the levee with points of discharge on the downgradient side), and fluxes are also relatively steady in magnitude compared with fluxes in the interior. Recharge flow paths are also relatively deep in their extent near levees, with fluxes passing entirely through the 1-m peat layer and inte

Nitrate in ground water and spring water near four dairy farms in North Florida, 1990-93

USGS Publications Warehouse

Andrews, W.J.

1994-01-01

Concentrations of nitrate and other selected water- quality characteristics were analyzed periodically for two years in water from 51 monitoring wells installed at four farms and in water discharging from three nearby springs along the Suwannee River in Lafayette and Suwannee Counties to examine the quality of ground water at these farms and the transport of nutrients in ground water to the nearby spring-fed Suwannee River: Ground water from shallow wells, which were completed in the top ten feet of the saturated zone in a surficial sandy aquifer and in the karstic Upper Floridan aquifer generally had the highest concentrations of nitrate, ranging from <.02 to 130 mg/L as nitrogen. Nitrate concentrations commonly exceeded the primary drinking water standard of 10 mg/L for nitrate as nitrogen in water from shallow wells, which tapped the top ten feet of the uppermost aquifers near waste-disposal areas such as wastewater lagoons and defoliated, intensive-use areas near milking barns. Upgradient from waste-disposal areas, concentrations of nitrate in ground water were commonly less than 1 mg/L as nitrogen. Water samples from deep wells (screened 20 feet deeper than shallow wells in these aquifers) generally had lower concentrations of nitrate (ranging from <0.02 to 84 mg/L) than water from shallow wells. Water samples from the three monitored springs (Blue, Telford, and Convict Springs) had nitrate concentrations ranging from 1.5 to 6.5 mg/L as nitrogen, which were higher than those typically occurring in water from upgradient wells at the monitored dairy farms or from back- ground wells sampled in the region. Analyses of nitrogen isotope ratios in nitrate indicated that leachate from animal wastes was the principal source of nitrate in ground water adjacent to waste-disposal areas at the monitored and unmonitored dairy farms. Leachate from a combi- nation of fertilizers, soils, and animal wastes appeared to be the source of nitrate in ground- water downgradient from pastures and wastewater spray fields at dairy farms and in water discharging from three nearby springs. Although denitrifying bacteria were present in counts sometimes exceeding 240,000 colonies/100mL in water from dairy-farm monitoring wells, ground water in the uppermost aquifers in Lafayette and Suwannee Counties generally contained too much oxygen for denitrification to remove nitrate from shallow ground water. Denitrification was more likely to occur in deeper ground water, which typically has lower dissolved oxygen concentrations.

Tracing organic carbon processes in a shallow coastal sandy aquifer

NASA Astrophysics Data System (ADS)

Meredith, K.; Andersen, M. S.; Baker, A.; O'Carrol, D. M.; Bryan, E.; Zainuddin, N. S.; Rutlidge, H.; McDonough, L.

2017-12-01

Coastal groundwater resources are likely to be impacted by climate change due to changes in recharge patterns, surface water flow and sea-level rise, which all have the potential to change how carbon is transported and stored within a catchment. Large quantities of carbon are currently stored within coastal wetland systems, so understanding carbon dynamics is important for climate change predictions into the future. Furthermore, dissolved organic carbon (DOC) can play a major role in weathering processes and deterioration of water quality, therefore understanding the sources, degradation pathways and its reactivity is important. Groundwater samples were collected from five nested sites (15 wells) from a shallow (0-20m) coastal sandy aquifer system located at Anna Bay, New South Wales, Australia. Surface water samples were also collected from the adjacent wetland. Waters were measured for major ion chemistry, carbon isotopes (δ13CDIC, δ13CDOC and 14CDIC) and tritium (3H). The dissolved organic matter (DOM) character was determined using optical spectroscopy and liquid chromatography. DOC was found to be elevated in the wetland (18 ppm) and had the lowest δ13CDOC value (-30.3 ‰). The shallow (3.5 m) groundwater located closest to but downgradient of the wetland (5 m) had similar characteristics to the wetland sample but contained significantly lower DOC concentrations (5 ppm) and were 1 ‰ more enriched in δ13CDOC values. This suggests that the aquifer is a sink for organic matter and the process fractionates the carbon isotopes. Higher resolution studies are underway to characterise and constrain timescales for the DOC transformation processes.

Geochemistry and potential environmental impact of the mine tailings at Rosh Pinah, southern Namibia

NASA Astrophysics Data System (ADS)

Nejeschlebová, L.; Sracek, O.; Mihaljevič, M.; Ettler, V.; Kříbek, B.; Knésl, I.; Vaněk, A.; Penížek, V.; Dolníček, Z.; Mapani, B.

2015-05-01

Mine tailings at Rosh Pinah located in semiarid southern Namibia were investigated by the combination of mineralogical methods and leaching using water and simulated gastric solution. They are well-neutralized with leachate pH > 7 and neutralization potential ratios (NPR) up to 4. Neutralization is mainly due to abundant Mn-rich dolomite in the matrix. Concentrations of released contaminants in water leachate follow the order Zn > Pb > Cu > As. Relatively high leached concentrations of Zn and partly also of Pb are caused by their link to relatively soluble carbonates and Mn-oxyhydroxides. In contrast, As is almost immobile by binding into Fe-oxyhydroxides, which are resistant to dissolution. Barium is released by the dissolution of Ba-carbonate (norsethite) and precipitates in sulfate-rich pore water as barite. Dissolved concentrations in neutral mine drainage water collected in the southern pond are low, but when total concentrations including colloidal fraction are taken into account, more than 70% of Zn is in colloidal form. Groundwater upgradient of the mine tailings is of poor quality and there seems to be no negative impact on groundwater downgradient from mine tailings. Contaminant concentrations in simulated gastric leachates are in the order Ba > Pb > Zn > Cu > As with a maximum gastric bioaccessibility of 86.6% for Ba and a minimum of 3.3% for As. These results demonstrate that total contaminant content and toxicity in the solid phase are poor predictors of risk, and therefore mineralogical and bioavailability/bioaccessibility studies are necessary for evaluation of contaminant environmental impact.

The thermal impact of subsurface building structures on urban groundwater resources - A paradigmatic example.

PubMed

Epting, Jannis; Scheidler, Stefan; Affolter, Annette; Borer, Paul; Mueller, Matthias H; Egli, Lukas; García-Gil, Alejandro; Huggenberger, Peter

2017-10-15

Shallow subsurface thermal regimes in urban areas are increasingly impacted by anthropogenic activities, which include infrastructure development like underground traffic lines as well as industrial and residential subsurface buildings. In combination with the progressive use of shallow geothermal energy systems, this results in the so-called subsurface urban heat island effect. This article emphasizes the importance of considering the thermal impact of subsurface structures, which commonly is underestimated due to missing information and of reliable subsurface temperature data. Based on synthetic heat-transport models different settings of the urban environment were investigated, including: (1) hydraulic gradients and conductivities, which result in different groundwater flow velocities; (2) aquifer properties like groundwater thickness to aquitard and depth to water table; and (3) constructional features, such as building depths and thermal properties of building structures. Our results demonstrate that with rising groundwater flow velocities, the heat-load from building structures increase, whereas down-gradient groundwater temperatures decrease. Thermal impacts on subsurface resources therefore have to be related to the permeability of aquifers and hydraulic boundary conditions. In regard to the urban settings of Basel, Switzerland, flow velocities of around 1 md -1 delineate a marker where either down-gradient temperature deviations or heat-loads into the subsurface are more relevant. Furthermore, no direct thermal influence on groundwater resources should be expected for aquifers with groundwater thicknesses larger 10m and when the distance of the building structure to the groundwater table is higher than around 10m. We demonstrate that measuring temperature changes down-gradient of subsurface structures is insufficient overall to assess thermal impacts, particularly in urban areas. Moreover, in areas which are densely urbanized, and where groundwater flow velocities are low, appropriate measures for assessing thermal impacts should specifically include a quantification of heat-loads into the subsurface which result in a more diffuse thermal contamination of urban groundwater resources. Copyright © 2017 Elsevier B.V. All rights reserved.

Groundwater geochemistry of Isla de Mona, Puerto Rico

USGS Publications Warehouse

Wicks, C.M.; Troester, J.W.

1998-01-01

In this study, we explore the differences between the hydrogeochemical processes observed in a setting that is open to input from the land surface and in a setting that is closed with respect to input from the land surface. The closed setting was a water-filled passage in a cave. Samples of groundwater and of a solid that appeared to be suspended in the relatively fresh region of saline-freshwater mixing zone were collected. The solid was determined to be aragonite. Based on the analyses of the composition and saturation state of the groundwater, the mixing of fresh and saline water and precipitation of aragonite are the controlling geochemical processes in this mixing zone. We found no evidence of sulfate reduction. Thus, this mixing zone is similar to that observed in Caleta Xel Ha, Quintana Roo, also a system that is closed with respect to input from the land surface. The open setting was an unconfined aquifer underlying the coastal plain along which four hand-dug wells are located. Two wells are at the downgradient ends of inferred flowpaths and one is along a flowpath. The composition of the groundwater in the downgradient wells is sulfide-rich and brackish. In contrast, at the well located along a flow line, the groundwater is oxygenated and brackish. All groundwater is oversaturated with respect to calcite, aragonite, and dolomite. The composition is attributed to mixing of fresh and saline groundwater, CO2 outgassing, and sulfate reduction. This mixing zone is geochemically similar to that observed in blue holes and cenotes.

Water-quality characteristics in the Black Hills area, South Dakota

USGS Publications Warehouse

Williamson, Joyce E.; Carter, Janet M.

2001-01-01

This report summarizes the water-quality characteristics of ground-water and surface-water in the Black Hills area. Differences in groundwater quality by aquifer and differences in surfacewater quality by water source are presented. Ground-water characteristics are discussed individually for each of the major aquifers in the Black Hills area, referred to herein as the Precambrian, Deadwood, Madison, Minnelusa, Minnekahta, and Inyan Kara aquifers. Characteristics for minor aquifers also are discussed briefly. Surface-water characteristics are discussed for hydrogeologic settings including headwater springs, crystalline core sites, artesian springs, and exterior sites. To characterize the water quality of aquifers and streams in the Black Hills area, data from the U.S. Geological Survey National Water Information System water-quality database were examined. This included samples collected as part of the Black Hills Hydrology Study as well as for other studies within the time frame of October 1, 1930, to September 30, 1998. Tables of individual results are not presented in this report, only summaries. Constituents summarized and discussed include physical properties, common ions, nutrients, trace elements, and radionuclides. Comparisons of concentration levels are made to drinking-water standards as well as beneficial-use and aquatic-life criteria. Ground water within the Black Hills and surrounding area generally is fresh and hard to very hard. Concentrations exceeding various Secondary and Maximum Contaminant Levels may affect the use of the water in some areas for many aquifers within the study area. Concentrations that exceed Secondary Maximum Contaminant Levels (SMCL's) generally affect the water only aesthetically. Radionuclide concentrations may be especially high in some of the major aquifers used within the study area and preclude the use of water in some areas. The sodiumadsorption ratio and specific conductance may affect irrigation use for some wells. High concentrations of iron and manganese are the only concentrations that may hamper the use of water from Precambrian aquifers. The principal deterrents to use of water from the Deadwood aquifer are the high concentrations of radionuclides as well as iron and manganese. Iron, manganese, and hardness may deter use of water from the Madison aquifer as well as dissolved solids and sulfate in downgradient wells (generally deeper than 2,000 feet). Iron, manganese, and hardness may also deter use of the Minnelusa aquifer. Water from the Minnekahta aquifer generally is suitable for all water uses although it is hard to very hard. High concentrations of dissolved solids, iron, sulfate, and manganese may hamper the use of water from the Inyan Kara aquifer. In the southern Black Hills, radium-226 and uranium concentrations also may preclude use of water from the Inyan Kara aquifer. Suitability for irrigation may be affected by high specific conductance and sodium-adsorption ratio for the Inyan Kara. Surface-water quality within the Black Hills and surrounding area generally is very good but the water is hard to very hard. Concentrations of some constituents in the study area tend to be higher exterior to the Black Hills, primarily due to influences from the Cretaceous-age marine shales, including dissolved solids, sodium, sulfate, selenium, and uranium. Headwater springs have relatively constant discharge, specific conductance, dissolved solids, and concentrations of most other constituents. Concentrations at crystalline core sites are very similar to those found in samples from Precambrian aquifers. Some high nitrate concentrations greater than the Maximum Contaminant Level (MCL) of 10 mg/L (milligrams per liter) have occurred at Annie Creek near Lead, which have been attributed to mining impacts. Trace elements generally are low with the exception of arsenic, for which 60 percent of samples exceed the proposed MCL of 10 ug/L (micrograms per liter) and one sample

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.

Carbon tetrachloride contamination in groundwater at Morrill, Kansas, was initially identified in 1985 during statewide testing of public water supply wells for volatile organic compounds (VOCs). High levels of nitrate were also present in the wells. The city of Morrill is located in Brown County in the northeastern corner of the state, about 7 mi east of Sabetha (Figure 1.1). The population of Morrill as of the 2010 Census was approximately 230 (down from 277 in 2000). All residents of Morrill now obtain their drinking water from the Sabetha municipal water system via a pipeline constructed in 1991. The findingsmore » of the April 2011 and October 2011 monitoring events at Morrill support the following conclusions: (1) Groundwater flow during the 2011 review period (as in prior years) was predominantly to the south, from the vicinity of the former CCC/USDA facility toward Terrapin Creek. Automatic water level monitoring data suggest that spring precipitation and recharge represent the predominant factors affecting the local groundwater level patterns. (2) No significant changes were observed in the concentration or distribution of carbon tetrachloride in groundwater during the spring and fall 2011 monitoring events versus the spring and fall 2010 monitoring events. In October 2011, a maximum carbon tetrachloride concentration of 49 {micro}g/L was identified in groundwater at well MW3S on the former CCC/USDA facility, with concentrations decreasing downgradient toward Terrapin Creek. (3) Since 2004, the accumulated results of 15 sampling events have demonstrated a significant decline in the maximum detected concentration of carbon tetrachloride in groundwater. In 1995, the contaminant was detected at the former CCC/USDA facility at 390 {micro}g/L, while the current maximum levels are < 50 {micro}g/L. The residual contaminant plume extending from the former CCC/USDA facility southward toward Terrapin Creek is well-defined and slowly declining in concentration naturally. (4) No carbon tetrachloride contamination was detected in 2011 in surface waters or shallow streambed sediments sampled at five locations along Terrapin Creek, downgradient from the former CCC/USDA facility. These results indicate that Terrapin Creek remains unaffected by the carbon tetrachloride plume. (5) Since 2007, the accumulated results of 10 monitoring events for surface water and sediment in Terrapin Creek have demonstrated no impact to the sediment and surface waters of the creek by carbon tetrachloride and no imminent risk for further degradation of the creek. (6) Terrapin Creek (tributary segment 308 to Walnut Creek) receives discharge from the Morrill wastewater treatment plant and several confined animal feeding operations regulated by the KDHE. The Walnut Creek watershed is designated by the KDHE as impaired by fecal coliform bacteria. Terrapin Creek is classified by the KDHE as not open to or accessible by the public for contact recreation and does not support the food procurement designated use (KDHE 2010b). (7) In July 2011, trace concentrations of carbon tetrachloride were detected in vegetation samples collected from trees at 2 of the 42 sampled locations south (downgradient) of the former CCC/USDA facility. (8) Sampling of indoor air in August 2010 to evaluate the potential for vapor intrusion into homes overlying and within 100 ft laterally of the identified carbon tetrachloride plume resulted in no detections of carbon tetrachloride. Low concentrations of chloroform, indicative of indoor air sources, were detected. Low radon levels were also detected. The results indicate no evidence of upward migration of vapors from the low-level carbon tetrachloride contamination in groundwater to indoor air.« less

Ground-water age, flow, and quality near a landfill, and changes in ground-water conditions from 1976 to 1996 in the Swinomish Indian Reservation, northwestern Washington

USGS Publications Warehouse

Thomas, B.E.; Cox, S.E.

1998-01-01

This report describes the results of two related studies: a study of ground-water age, flow, and quality near a landfill in the south-central part of the Swinomish Indian Reservation; and a study of changes in ground-water conditions for the entire reservation from 1976 to 1996. The Swinomish Indian Reservation is a 17-square-mile part of Fidalgo Island in northwestern Washington. The groundwater flow system in the reservation is probably independent of other flow systems in the area because it is almost completely surrounded by salt water. There has been increasing stress on the ground-water resources of the reservation because the population has almost tripled during the past 20 years, and 65 percent of the population obtain their domestic water supply from the local ground-water system. The Swinomish Tribe is concerned that increased pumping of ground water might have caused decreased ground-water discharge into streams, declines in ground-water levels, and seawater intrusion into the ground-water system. There is also concern that leachate from an inactive landfill containing mostly household and wood-processing wastes may be contaminating the ground water. The study area is underlain by unconsolidated glacial and interglacial deposits of Quaternary age that range from about 300 to 900 feet thick. Five hydrogeologic units have been defined in the unconsolidated deposits. From top to bottom, the hydrogeologic units are a till confining bed, an outwash aquifer, a clay confining bed, a sea-level aquifer, and an undifferentiated unit. The ground-water flow system of the reservation is similar to other island-type flow systems. Water enters the system through the water table as infiltration and percolation of precipitation (recharge), then the water flows downward and radially outward from the center of the island. At the outside edges of the system, ground water flows upward to discharge into the surrounding saltwater bodies. Average annual recharge is estimated to be about 3 inches, or 12 percent of the average annual precipitation. Ground water in the outwash aquifer near the landfill is estimated to be between 15 and 43 years old. Some deeper ground waters and ground water near the discharge areas close to the shoreline are older than 43 years. Analysis of water-quality data collected for this study and review of existing data indicate that material in the landfill has had no appreciable impact on the current quality of ground water outside of the landfill. The water quality of samples from seven wells near to and downgradient from the landfill appears to be similar to the ground-water quality throughout the entire study area. The high iron and manganese concentrations found in most of the samples from wells near the landfill are probably within the range of natural concentrations for the study area. Ground-water pumping during the past 20 years has not caused any large changes in ground-water discharge to streams, ground-water levels, or seawater intrusion into the ground-water system. Ground-water discharge into Snee-oosh Creek and Munks Creek had similar magnitudes in the summers of 1976 and 1996; flows in both creeks during those summers ranged from 0.07 t 0.15 cubic feet per second. Ground-water levels changed minimally between 1976 and 1996. The average water-level change for 20 wells with more than 10 years between measurements was -0.7 feet and the two largest waterlevel declines were 6 and 9 feet. No appreciable seawater intrusion was found in the ground water in 1996, and there was no significant increase in the extent of seawater intrusion from 1976 to 1996. Median chloride concentrations of water samples collected from wells were 22 milligrams per liter in 1976 and 18 milligrams per liter in 1996.

Presence, distribution, and potential sources of nitrate and selected pesticides in the surficial aquifer along the Straight River in north-central Minnesota, 1992-93

USGS Publications Warehouse

Ruhl, J.F.

1995-01-01

Upgradient to downgradient mean or individual nitrogen isotope δ15N values in %o (delta units in parts per thousand) determined for sampled monitoring wells along the direction of ground-water flow through the five land-use settings were: (1) 5.1 %o and 4.0 %o for the feedlot and adjacent manured field; (2) 1.1 %o and 0.9 %o for the cultivated croplands irrigated with waste water; (3) 3.8 %o and 2.7 %o for the cultivated croplands irrigated with ground water; (4) 3.4 %o and 4.9 %o for the residential development; and (5) 1.7 %o and 3.0 %o for the three waste-water lagoons. Nitrate from fertilizer appeared to have been present in ground water at the waste-water lagoons, cultivated croplands irrigated with waste water, and cultivated croplands irrigated with ground water. Nitrate from soil organic matter rather than from animal waste appeared to have been present in ground water at the feedlot and adjacent manured field.

Geohydrology of, and nitrogen and chloride in, the glacial aquifer, Milford-Matamoras area, Pike County, Pennsylvania

USGS Publications Warehouse

Senior, L.A.

1994-01-01

The glacial aquifer that underlies the Routes 209 and 6 corridor between Milford and Matamoras, Pa., is one of the most productive in Pike County. The aquifer is comprised of unconsolidated glacial outwash and kame-terrace deposits that lie within a glacially carved valley now occupied by the Delaware River. Most businesses and residences along this narrow, 7-mile-long corridor rely on individual wells for water supply and septic systems for waste-water disposal. A study of nutrients and chloride in ground water in the glacial aquifer was conducted to determine the effect of these constituents contributed from septic systems and road runoff on ground-water quality. Sources of nutrients and chloride in the recharge zone upgradient of the aquifer include road and parking-lot runoff, septic systems, and precipitation. Nitrate and chloride from these sources can infiltrate and move in the direction of ground-water flow in the saturated zone of the aquifer. A water-table map based on 29 water levels measured in August 1991 indicates that the direction of ground-water flow is from the edges of the valley toward t he Delaware River but is nearly parallel to the Delaware River in the central area of the valley. The average concentrations of nitrogen and chloride in recharge and total annual loads of nitrogen and chloride to ground water were estimated for six areas with different population densities. These estimates assumed a recharge rate to the glacial aquifer of 20 inches per year and a 15 percent loss of chloride and nitrogen in the atmospheric precipitation to surface runoff. The estimated average concentration of nitrogen in recharge ranged from 2.5 to 10 mg/L (milligrams per liter), which corresponds to a total annual load of nitrogen as ammonium released from septic tanks and present in precipitation was oxidized to nitrate as the dominant nitrogen species in ground water. Contributions of nitrogen from septic tanks were greater than contributions from runoff. Observed concentrations of nitrate, which was the most abundant nitrogen species in ground water in t he glacial aquifer, ranged from less than 0.05 to 5.1 mg/L as nitrogen, with a median of 1.1 mg/L as nitrogen. Concentrations of nitrogen measured in ground water were lower than estimated concentrations for recharge suggesting that dissolved nitrogen species may not be conservative in ground water. Nitrate is unstable in anoxic ground water and can be removed by denitrification. Ammonium can be sorbed onto the aquifer materials. Evidence for reducing conditions included a positive correlation between low concentrations of dissolved oxygen and low concentrations of nitrate. The estimated concentration of chloride in recharge ranged from 6.7 to 21 mg/L, and total annual load of chloride to ground water ranged from 19.4 to 50.6 x 10(3) lb/mi2. Chloride is considered to be a chemically conservative ion in ground water. Contributions of chloride to ground water from road salting were greater than contributions from septic tanks. Observed concentrations of chloride in 18 ground-water samples from the glacial aquifer ranged from 2.1 to 32 mg/L, with a median of 17.5 mg/L. Local contamination is indicated by the elevated concentrations of chloride (up to 680 mg/L) detected in four wells located downgradient of an abandoned industry that may have released salts in processing waste. Chloride concentrations in ground water appeared to be greater near major roads and in areas of relatively greater septic-system density than in areas upgradient of roads, farther downgradient from roads, or with less densely spaced septic systems.

Momentum and buoyancy transfer in atmospheric turbulent boundary layer over wavy water surface - Part 1: Harmonic wave

NASA Astrophysics Data System (ADS)

Troitskaya, Yu. I.; Ezhova, E. V.; Zilitinkevich, S. S.

2013-10-01

The surface-drag and mass-transfer coefficients are determined within a self-consistent problem of wave-induced perturbations and mean fields of velocity and density in the air, using a quasi-linear model based on the Reynolds equations with down-gradient turbulence closure. Investigation of a harmonic wave propagating along the wind has disclosed that the surface drag is generally larger for shorter waves. This effect is more pronounced in the unstable and neutral stratification. The stable stratification suppresses turbulence, which leads to weakening of the momentum and mass transfer.

The Lincolnshire Limestone — Hydrogeochemical evolution over a ten-year period

NASA Astrophysics Data System (ADS)

Edmunds, W. M.; Walton, N. R. G.

1983-02-01

In the Lincolnshire (Jurassic) Limestone of Britain, a sequence of hydrogeochemical processes along a 28-km flow line was defined in 1969. These processes include solution, redox and ion-exchange reactions, sulphate reduction and mixing with saline formation water. Resampling of the aquifer profile after 10 years has confirmed the overall sequence, although downgradient increases in both sulphate and calcium, together with changes in redox system, can be recognised. These changes are related to the migration of agrichemical pollutants and the results demonstrate that the aquifer must have a significant capacity for in situ nitrate reduction.

Use of chemical and isotopic tracers to characterize the interactions between ground water and surface water in mantled karst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katz, B.G.; Davis, J.H.; Coplen, T.B.

1997-11-01

In the mantled karst terrane of northern Florida, the water quality of the Upper Floridan aquifer is influenced by the degree of connectivity between the aquifer and the surface. Chemical and isotopic analyses [{sup 18}O/{sup 16}O ({delta}{sup 18}O), {sup 2}H/{sup 1}H ({delta}D), {sup 13}C/{sup 12}C ({delta}{sup 13}C), tritium ({sup 3}H), and strontium-87/strontium-86 ({sup 87}Sr/{sup 86}Sr)] along with geochemical mass-balance modeling were used to identify the dominant hydrochemical processes that control the composition of ground water as it evolves downgradient in two systems. In one system, surface water enters the Upper Florida aquifer through a sinkhole located in the Northern Highlandsmore » physiographic unit. In the other system, surface water enters the aquifer through a sinkhole lake (Lake Bradford) in the Woodville Karst Plain. Differences in the composition of water isotopes ({delta}{sup 18}O and {delta}D) in rainfall, ground water, and surface water were used to develop mixing models of surface water (leakage of water to the Upper Floridan aquifer from a sinkhole lake and a sinkhole) and ground water. Using mass-balance calculations, based on differences in {delta}{sup 18}O and {delta}D, the proportion of lake water that mixed with meteoric water ranged from 7 to 86% in water from wells located in close proximity to lake Bradford. In deeper parts of the Upper Floridan aquifer, water enriched in {sup 18}O and D from five of 12 samples municipal wells indicated that recharge from a sinkhole (1 to 24%) and surface water with an evaporated isotopic signature (2 to 32%) was mixing with ground water. The solute isotopes, {delta}{sup 13}C and {sup 87}Sr/{sup 86}Sr, were used to test the sensitivity of binary and ternary mixing models, and to estimate the amount of mass transfer of carbon and other dissolved species in geochemical reactions.« less

Geochemistry of ground water in the Gallup, Dakota, and Morrison aquifers, San Juan Basin, New Mexico

USGS Publications Warehouse

Dam, W.L.

1995-01-01

Ground water was sampled from wells completed in the Gallup, Dakota, and Morrison aquifers in the San Juan Basin, New Mexico, to examine controls on solute concentrations. Samples were collected from 38 wells primarily from the Morrison aquifer (25 wells) in the northwestern part of the basin. A series of samples was collected along ground-water flow paths; dissolved constituents varied horizontally and vertically. The understanding of the flow system changed as a result of the geochemical analyses. The conceptual model of the flow system in the Morrison aquifer prior to the study reported here assumed the Westwater Canyon Member of the Morrison aquifer as the only significant regional aquifer; flow was assumed to be two dimensional; and vertical leakage was assumed to be negligible. The geochemical results indicate that the Westwater Canyon Member is not the only major water-yielding zone and that the flow system is three dimensional. The data presented in this report suggest an upward component of flow into the Morrison aquifer. The entire section above and below the Morrison aquifer appears to be controlled by a three-dimensional flow regime where saline brine leaks near the San Juan River discharge area. Predominant ions in the Gallup aquifer were calcium bicarbonate in recharge areas and sodium sulfate in discharge areas. In the Dakota aquifer, predominant ions were sodium bicarbonate and sodium sulfate. Water in the Morrison aquifer was predominantly sodium bicarbonate in the recharge area, changing to sodium sulfate downgradient. Chemical and radioisotopic data indicate that water from overlying and underlying units mixes with recharge water in the Morrison aquifer. Recharge water contained a large ratio of chlorine-36 to chlorine and a small ratio of bromide to chloride. Approximately 10 miles downgradient, samples from four wells completed in the Morrison aquifer were considerably different in composition compared to recharge samples. Oxygen stable isotopes decreased by 2.8 per mil and deuterium decreased 26 per mil, relative to recharge. Carbon-14 radioisotope activities were not detectable. Chloride-36 radioisotope ratios were small and bromide to chloride concentration ratios were large. These results suggest two potentially viable processes: ion filtration or trapping of ancient dilute water recharged under a humid climate. For water samples near the San Juan River, pH decreased to about 8.0, chloride concentrations increased to more than 100 milligrams per liter, and ratios of chlorine-36 to chlorine and bromide to chloride were small. Leakage of deep basin brine into the fresher water of the Morrison aquifer appears to control ion concentrations.

Elements in cottonwood trees as an indicator of ground water contaminated by landfill leachate

USGS Publications Warehouse

Erdman, James A.; Christenson, Scott

2000-01-01

Ground water at the Norman Landfill Research Site is contaminated by a leachate plume emanating from a closed, unlined landfill formerly operated by the city of Norman, Oklahoma, Ground water contaminated by the leachate plume is known to be elevated in the concentration of many, organic and inorganic constituents. Specific conductance, alkalinity, chloride, dissolved organic carbon, boron, sodium, strontium, and deuterium in ground water are considered to be indicators of the leachate plume at this site. Leaf samples of broad-leafed cottonwood, Populus deltoides, were collected from 57 sites around the closed landfill. Cottonwood, a phreatophyte or “well plant,” functions as a & surrogate well and serves as a ground water quality sampler. The leaf samples were combusted to ash and analyzed by instrumental neutron activation for 35 elements and by prompt-gamma instrumental neutron activation, for boron. A monitoring well was located within a few meters of a sampled cottonwood tree at 15 of the 57 sites, and ground water samples were collected from these monitoring wells simultaneously with a leaf sample. The chemical analyses of the ground water and leaf samples from these 15 sites indicated that boron, bromine, sodium, and strontium concentrations in leaves were significantly correlated with leachate indicator constituents in ground water. A point-plot map of selected percentiles indicated high concentrations of boron, bromine, and sodium in leaf ash from sites downgradient of the most recent landfill and from older landfills nearby. Data from leaf analysis greatly extended the known areal extent of the leachate plume previously determined from a network of monitoring wells and geophysical surveys. This phytosgeochemical study provided a cost-effective method for assessing the extent of a leachate plume from an old landfill. Such a method may be useful as a preliminary sampling tool to guide the design of hydrogeochemical and geophysical studies.

2014 Annual Industrial Wastewater Reuse Report for the Idaho National Laboratory Site’s Advanced Test Reactor Complex Cold Waste Pond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Mike

This report describes conditions, as required by the state of Idaho Industrial Wastewater Reuse Permit (LA 000161 01, Modification B), for the wastewater land application site at the Idaho National Laboratory Site’s Advanced Test Reactor Complex Cold Waste Pond from November 1, 2013–October 31, 2014. The report contains the following information; Facility and system description; Permit required effluent monitoring data and loading rates; Permit required groundwater monitoring data; Status of compliance activities; Noncompliance issues; and Discussion of the facility’s environmental impacts. During the 2014 permit year, approximately 238 million gallons of wastewater were discharged to the Cold Waste Pond. Thismore » is well below the maximum annual permit limit of 375 million gallons. As shown by the groundwater sampling data, sulfate and total dissolved solids concentrations are highest near the Cold Waste Pond and decrease rapidly as the distance from the Cold Waste Pond increases. Although concentrations of sulfate and total dissolved solids are elevated near the Cold Waste Pond, both parameters are below the Ground Water Quality Rule Secondary Constituent Standards in the downgradient monitoring wells.« less

Ground-Water Nutrient Flux to Coastal Waters and Numerical Simulation of Wastewater Injection at Kihei, Maui, Hawaii

USGS Publications Warehouse

Hunt, Charles D.

2007-01-01

Water sampling and numerical modeling were used to estimate ground-water nutrient fluxes in the Kihei area of Maui, where growth of macroalgae (seaweed) on coral reefs raises ecologic concerns and accumulation on beaches has caused odor and removal problems. Fluxes and model results are highly approximate, first-order estimates because very few wells were sampled and there are few field data to constrain model calibration. Ground-water recharge was estimated to be 22.6 Mgal/d (million gallons per day) within a 73-square-mile area having a coastline length of 8 miles or 13 km (kilometers). Nearly all of the recharge discharges at the coast because ground-water withdrawals are small. Another 3.0 Mgal/d of tertiary-treated wastewater effluent is injected into the regional aquifer at a County treatment plant midway along the coast and about a mile from shore. The injection plume is 0.93 miles wide (1.5 km) at the shore, as estimated from a three-dimensional numerical ground-water model. Wastewater injected beneath the brackish ground-water lens rises buoyantly and spreads out at the top of the lens, diverting and mixing with ambient ground water. Ground water discharging from the core of the injection plume is less than 5 years old and is about 60 percent effluent at the shore, according to the model. Dissolved nitrogen and phosphorus concentrations in treated effluent were 7.33 and 1.72 milligrams per liter, roughly 6 and 26 times background concentrations at an upgradient well. Background nitrogen and phosphorus fluxes carried by ground water are 7.7 and 0.44 kg/d-km (kilograms per day per kilometer of coast). Injected wastewater fluxes distributed across the plume width are 55 and 13 kg/d-km nitrogen and phosphorus, roughly 7 and 30 times background flux. However, not all of the injected load reaches coastal waters because nutrients are naturally attenuated in the oxygen-depleted effluent plume. Water from a downgradient well reflects this attenuation and provides a more conservative estimate of injection flux approaching the shore: 27 and 1.5 kg/d-km nitrogen and phosphorus, roughly one-half and one-ninth the injection-source estimates, and 3.5 and 3.4 times background flux. Effluent has 8 O and 2 H stable-isotope signatures that are distinct from local ground water, as well as 15 N and 11 B signatures diagnostic of domestic waste and laundry detergents, respectively. Pharmaceuticals and organic wastewater compounds also were present in effluent and the downgradient well. These isotopes and chemicals served as wastewater tracers in Kihei ground water and may be useful tracers in nearshore marine waters and aquifers elsewhere in Hawaii.

Construction, lithologic, and water-level data for wells near the Dickson County landfill, Dickson County, Tennessee, 1995

USGS Publications Warehouse

Ladd, D.E.

1996-01-01

Organic compounds were detected in water samples collected from Sullivan Spring during several sampling events in 1994. Prior to this, the spring was the drinking-water source for two families in the Dickson, Tennessee area. An investigation was conducted by the U.S. Geological Survey, in cooperation with Dickson County Solid Waste Management, to determine if Sullivan Spring is hydraulically downgradient from the Dickson County landfill. This report describes the data collected during the investigation. Five monitoring wells were installed near the northwestern corner of the landfill at points between the landfill and Sullivan Spring. Water-level measurements were made on June 1 and 2, 1995, at these wells and 13 other wells near the landfill to determine ground- water altitudes in the area. Water-level altitudes in the five new monitoring wells and three other landfill-monitoring wells were higher (750.04 to 800.17 feet) than the altitude of Sullivan Spring (approximately 725 feet). In general, wells in topographically high areas had higher water-level altitudes than Sullivan Spring and wells near streams in lowland areas.

Microbial control of mineral–groundwater equilibria:Macroscale to microscale

USGS Publications Warehouse

Bennett, Philip C.; Hiebert, Franz K.; Roger, Jennifer Roberts

2000-01-01

macroscaleprocesses that perturb general groundwater chemistry and therefore mineral–water equilibria; and microscale interactions, where attached organisms locally perturb mineral–water equilibria, potentially releasing limiting trace nutrients from the dissolving mineral.In the contaminated unconfined glacio-fluvial aquifer near Bemidji, Minnesota, USA, carbonate chemistry is influenced primarily at the macroscale. Under oxic conditions, respiration by native aerobic heterotrophs produces excess carbon dioxide that promotes calcite and dolomite dissolution. Aerobic microorganisms do not colonize dolomite surfaces and few occur on calcite. Within the anoxic groundwater, calcite overgrowths form on uncolonized calcite cleavage surfaces, possibly due to the consumption of acidity by dissimilatory iron-reducing bacteria. As molecular oxygen concentration increases downgradient of the oil pool, aerobes again dominate and residual hydrocarbons and ferrous iron are oxidized, resulting in macroscale carbonate-mineral dissolution and iron precipitation.

Hydrogeology, ground-water quality, and potential for water-supply contamination near the Shelby County landfill in Memphis, Tennessee

USGS Publications Warehouse

Parks, W.S.; Mirecki, J.E.

1992-01-01

An investigation was conducted from 1989 to 1991 to collect and interpret hydrogeologic and ground-water-quality data specific to the Shelby County landfill in east Memphis, Tennessee. Eighteen wells were installed in the alluvial and Memphis aquifers at the landfill. Hydrogeologic data collected showed that the confining unit separating the alluvial aquifer from the Memphis aquifer was thin or absent just north of the landfill and elsewhere consists predominantly of fine sand and silt with lenses of clay. A water-table map of the landfill vicinity confirms the existence of a depression in the water table north and northeast of the landfill and indicates that ground water flows northeast from the Wolf River passing beneath the landfill toward the depression in the water table. A map of the potentiometric surface of the Memphis aquifer shows that water levels were anomalously high just north of the landfill, indicating downward leakage of water from the alluvial aquifer to the Memphis aquifer. An analysis of water-quality data for major and trace inorganic constituents and nutrients confirms that leachate from the landfill has migrated northeastward in the alluvial aquifer toward the depression in the water table and that contaminants in the alluvial aquifer have migrated downward into the Memphis aquifer. The leachate plume can be characterized by concentrations of certain major and trace inorganic constituents that are 2 to 20 times higher than samples from upgradient and background alluvial aquifer wells. The major and trace constituents that best characterize the leachate plume are total organic carbon, chloride, dissolved solids, iron, ammonia nitrogen, calcium, sodium, iodide, barium, strontium, boron, and cadmium. Several of these constituents (specifically dissolved solids, calcium, sodium, and possibly ammonia nitrogen, chloride, barium, and strontium) were detected in elevated concentrations in samples from certain Memphis aquifer wells. Elevated concentrations were detected in samples from the Memphis aquifer beneath the leachate plume where the confining unit is thin or absent. The distribution of halogenated alkanes (specifically dichlorodifluoromethane and trichlorofluoromethane) and halogenated alkenes (specifically 1,2-trans-dichloroethene and vinyl chloride) in samples from wells screened in both the alluvial and Memphis aquifers is similar to the distribution of major and trace inorganic constituents that characterize the leachate plume. The ground-water supply most susceptible to contamination from the Shelby County landfill is the Sheahan well field of the Memphis Light, Gas and Water Division. This well field is about 5 miles downgradient from the landfill in the direction of ground-water flow. Based on an estimated velocity of 0.5 to 1.5 feet per day, ground water would require about 50 to 150 years to travel from the Shelby County landfill to the Sheahan wellfield. Given the time and distance of transport, any contaminants in the ground water would not likely persistto reach this well field because of the effects of various physical, chemical, and biological processes, including dilution and adsorption.

Fate of para-toluenesulfonamide (p-TSA) in groundwater under anoxic conditions: modelling results from a field site in Berlin (Germany).

PubMed

Meffe, Raffaella; Kohfahl, Claus; Hamann, Enrico; Greskowiak, Janek; Massmann, Gudrun; Dünnbier, Uwe; Pekdeger, Asaf

2014-01-01

This article reports on a field modelling study to investigate the processes controlling the plume evolution of para-toluenesulfonamide (p-TSA) in anoxic groundwater in Berlin, Germany. The organic contaminant p-TSA originates from the industrial production process of plasticisers, pesticides, antiseptics and drugs and is of general environmental concern for urban water management. Previous laboratory studies revealed that p-TSA is degradable under oxic conditions, whereas it appears to behave conservatively in the absence of oxygen (O2). p-TSA is ubiquitous in the aquatic environment of Berlin and present in high concentrations (up to 38 μg L(-1)) in an anoxic aquifer downgradient of a former sewage farm, where groundwater is partly used for drinking water production. To obtain refined knowledge of p-TSA transport and degradation in an aquifer at field scale, measurements of p-TSA were carried out at 11 locations (at different depths) between 2005 and 2010. Comparison of chloride (Cl(-)) and p-TSA field data showed that p-TSA has been retarded in the same manner as Cl(-). To verify the transport behaviour under field conditions, a two-dimensional transport model was setup, applying the dual-domain mass transfer approach in the model sector corresponding to an area of high aquifer heterogeneity. The distribution of Cl(-) and p-TSA concentrations from the site was reproduced well, confirming that both compounds behave conservatively and are subjected to retardation due to back diffusion from water stagnant zones. Predictive simulations showed that without any remediation measures, the groundwater quality near the drinking water well galleries will be affected by high p-TSA loads for about a hundred years.

Hydrology and chemistry of selected prairie wetlands in the Cottonwood Lake area, Stutsman County, North Dakota, 1979-82

USGS Publications Warehouse

LaBaugh, J.W.; Winter, T.C.; Adomaitis, V.A.; Swanson, G.A.

1987-01-01

The relation of hydrologic setting and temporal variability in hydrology to nutrient content and geochemical characteristics of a group of prairie wetlands and adjacent ground water was studied during the period 1979-82. Although data were collected from many wetlands and wells at the study site, emphasis in this report primarily is on four wetlands two seasonal and two semipermanent and four wells contiguous to them along a hydrologic section. The seasonal wetlands, T8 and T3, contained water only for a few weeks to months after filling in spring and early summer; both were completely dry by August. The semipermanent wetlands, PI and P8, contained water throughout each year and were ice covered in winter. One wetland, T8, recharges ground water. Wetlands PI and P8 are in areas of ground-water discharge. None of the wetlands received water by channelized surface-water inlets. Only wetland P8 had a channelized surface-water outlet. Ground-water-level data showed that high points of the water table did not always occur beneath land-surface highs. Reversals of ground-water flow occurred occasionally between two of the wetlands, T3 and PI.Significant differences existed in the chemical composition of the wetlands based on their hydrologic setting. In general, the dominant cation and anion in the wetlands were potassium and bicarbonate in wetland T8, calcium and sulfate in wetland T3, magnesium and sulfate in wetland PI, and magnesium and bicarbonate in wetland P8. Significant seasonal differences existed in the water chemistry of the wetlands in ground-water discharge areas. Water in three of the wetlands, T3, Pi, and P8, was most dilute while they filled in spring after icemelt. Concentration increased during the open-water period, and two of the wetlands, PI and P8, became most concentrated under ice cover. Concentrations of total phosphorus and total nitrogen were greatest in wetlands in areas of ground-water recharge and least in wetlands in areas of ground-water discharge. Differences in the chemistry of water from wells in the adjacent ground water resulted primarily from the positions of the wells in the ground-water flow system. The chemical type of water from well 12, which was located in a ground-water recharge area, was calcium sodium bicarbonate. Water from well 4, located downgradient from wetland T8, and from well 16, located downgradient from wetland PI, typically was a calcium sulfate type. Water from well 13, located between wetlands T3 and PI in an area of changing ground-water flow directions, was a magnesium sulfate type. Data from this study show that an understanding of hydrologic conditions is important in the interpretation of the water chemistry of wetlands in the study area.

A Binomial Modeling Approach for Upscaling Colloid Transport Under Unfavorable Attachment Conditions: Emergent Prediction of Nonmonotonic Retention Profiles

NASA Astrophysics Data System (ADS)

Hilpert, Markus; Johnson, William P.

2018-01-01

We used a recently developed simple mathematical network model to upscale pore-scale colloid transport information determined under unfavorable attachment conditions. Classical log-linear and nonmonotonic retention profiles, both well-reported under favorable and unfavorable attachment conditions, respectively, emerged from our upscaling. The primary attribute of the network is colloid transfer between bulk pore fluid, the near-surface fluid domain (NSFD), and attachment (treated as irreversible). The network model accounts for colloid transfer to the NSFD of downgradient grains and for reentrainment to bulk pore fluid via diffusion or via expulsion at rear flow stagnation zones (RFSZs). The model describes colloid transport by a sequence of random trials in a one-dimensional (1-D) network of Happel cells, which contain a grain and a pore. Using combinatorial analysis that capitalizes on the binomial coefficient, we derived from the pore-scale information the theoretical residence time distribution of colloids in the network. The transition from log-linear to nonmonotonic retention profiles occurs when the conditions underlying classical filtration theory are not fulfilled, i.e., when an NSFD colloid population is maintained. Then, nonmonotonic retention profiles result potentially both for attached and NSFD colloids. The concentration maxima shift downgradient depending on specific parameter choice. The concentration maxima were also shown to shift downgradient temporally (with continued elution) under conditions where attachment is negligible, explaining experimentally observed downgradient transport of retained concentration maxima of adhesion-deficient bacteria. For the case of zero reentrainment, we develop closed-form, analytical expressions for the shape, and the maximum of the colloid retention profile.

Fate and transport of petroleum hydrocarbons in soil and ground water at Big South Fork National River and Recreation Area, Tennessee and Kentucky, 2002-2003

USGS Publications Warehouse

Williams, Shannon D.; Ladd, David E.; Farmer, James

2006-01-01

In 2002 and 2003, the U.S. Geological Survey (USGS), by agreement with the National Park Service (NPS), investigated the effects of oil and gas production operations on ground-water quality at Big South Fork National River and Recreation Area (BISO) with particular emphasis on the fate and transport of petroleum hydrocarbons in soils and ground water. During a reconnaissance of ground-water-quality conditions, samples were collected from 24 different locations (17 springs, 5 water-supply wells, 1 small stream, and 1 spring-fed pond) in and near BISO. Benzene, toluene, ethylbenzene, and xylene (BTEX) compounds were not detected in any of the water samples, indicating that no widespread contamination of ground-water resources by dissolved petroleum hydrocarbons probably exists at BISO. Additional water-quality samples were collected from three springs and two wells for more detailed analyses to obtain additional information on ambient water-quality conditions at BISO. Soil gas, soil, water, and crude oil samples were collected at three study sites in or near BISO where crude oil had been spilled or released (before 1993). Diesel range organics (DRO) were detected in soil samples from all three of the sites at concentrations greater than 2,000 milligrams per kilogram. Low concentrations (less than 10 micrograms per kilogram) of BTEX compounds were detected in lab-analyzed soil samples from two of the sites. Hydrocarbon-degrading bacteria counts in soil samples from the most contaminated areas of the sites were not greater than counts for soil samples from uncontaminated (background) sites. The elevated DRO concentrations, the presence of BTEX compounds, and the low number of -hydrocarbon-degrading bacteria in contaminated soils indicate that biodegradation of petroleum hydrocarbons in soils at these sites is incomplete. Water samples collected from the three study sites were analyzed for BTEX and DRO. Ground-water samples were collected from three small springs at the two sites located on ridge tops. BTEX and DRO were not detected in any of the water samples, and petroleum hydrocarbons do not appear to have leached into ground water at these sites. Ground-water samples were collected from a small spring and from three auger holes at the third site, which is located in a stream valley. BTEX and DRO were not detected in these ground-water samples, and currently, petroleum hydrocarbons do not appear to be leaching into ground water at this site. Weathered crude oil, however, was detected at the water surface in one of the auger holes, indicating that soluble petroleum hydrocarbons may have leached into the ground water and may have migrated downgradient from the site in the past. The concentration of soluble petroleum hydrocarbons present in the ground water would depend on the concentration of the hydrocarbons in the crude oil at the site. A laboratory study was conducted to examine the dissolution of petroleum hydrocarbons from a fresh crude oil sample collected from one of the study sites. The effective solubility of benzene, toluene, ethylbenzene, and total xylenes for the crude oil sample was determined to be 1,900, 1,800, 220, and 580 micrograms per liter (?g/L), respectively. These results indicate that benzene and toluene could be present at concentrations greater than maximum contaminant levels (5 ?g/L for benzene and 1,000 ?g/L for toluene for drinking water) in ground water that comes into contact with fresh crude oil from the study area.

Age and quality of ground water and sources of nitrogen in the aquifers in Pumpkin Creek Valley, western Nebraska, 2000

USGS Publications Warehouse

Steele, G.V.; Cannia, J.C.; Sibray, S.S.; McGuire, V.L.

2005-01-01

Ground water is the source of drinking water for the residents of Pumpkin Creek Valley, western Nebraska. In this largely agricultural area, shallow aquifers potentially are susceptible to nitrate contamination. During the last 10 years, ground-water levels in the North Platte Natural Resources District have declined and contamination has become a major problem for the district. In 2000, the U.S. Geological Survey and the North Platte Natural Resources District began a cooperative study to determine the age and quality of the ground water and the sources of nitrogen in the aquifers in Pumpkin Creek Valley. Water samples were collected from 8 surface-water sites, 2 springs, and 88 ground-water sites during May, July, and August 2000. These samples were analyzed for physical properties, nutrients or nitrate, and hydrogen and oxygen isotopes. In addition, a subset of samples was analyzed for any combination of chlorofluorocarbons, tritium, tritium/helium, sulfur-hexafluoride, carbon-14, and nitrogen-15. The apparent age of ground water in the alluvial aquifer typically varied from about 1980 to modern, whereas ground water in the fractured Brule Formation had a median value in the 1970s. The Brule Formation typically contained ground water that ranged from the 1940s to the 1990s, but low-yield wells had apparent ages of 5,000 to 10,000 years before present. Data for oxygen-18 and deuterium indicated that lake-water samples showed the greatest effects from evaporation. Ground-water data showed no substantial evaporative effects and some ground water became isotopically heavier as the water moved downgradient. In addition, the physical and chemical ground-water data indicate that Pumpkin Creek is a gaining stream because little, if any, of its water is lost to the ground-water system. The water-quality type changed from a sodium calcium bicarbonate type near Pumpkin Creek's headwaters to a calcium sodium bicarbonate type near its mouth. Nitrate concentrations were largest in the alluvial system (median = 5 mg/L) and smallest in the surface-water system (median = 1 mg/L). Most nitrate concentrations exceeding the U.S. Environmental Protection Agency maximum contaminant level for drinking water of 10 mg/L as nitrogen were adjacent to irrigated fields and in areas where alluvial sediments are less than 50 ft thick. Sources of nitrogen in the ground water of the study area included naturally occurring nitrogen, commercial fertilizer, and animal waste. Based on nitrate concentration and delta nitrogen-15, the nitrogen in 65 percent of the water samples appears to have originated from a mixture of commercial fertilizers and animal waste. Some of the smallest nitrate concentrations in the ground-water samples contained some of the largest delta nitrogen-15 values (greater than 10 per mil), which suggests animal waste as the likely source. Commercial fertilizers were the likely source of most of the nitrogen in water samples with nitrate concentrations that exceeded 10 mg/L. The source of the nitrogen in water samples with nitrate concentrations exceeding 10 mg/L, but with delta nitrogen-15 values close to 10 per mil, could not be determined.

Hydrogeology and water quality in the Snake River alluvial aquifer at Jackson Hole Airport, Jackson, Wyoming, September 2008-June 2009

USGS Publications Warehouse

Wright, Peter R.

2010-01-01

The hydrogeology and water quality of the Snake River alluvial aquifer, at the Jackson Hole Airport in northwest Wyoming, was studied by the U.S. Geological Survey in cooperation with the Jackson Hole Airport Board and the Teton Conservation District during September 2008-June 2009. Hydrogeologic conditions were characterized using data collected from 14 Jackson Hole Airport wells. Groundwater levels are summarized in this report and the direction of groundwater flow, hydraulic gradients, and estimated groundwater velocity rates in the Snake River alluvial aquifer underlying the study area are presented. Analytical results of chemical, dissolved gas, and stable isotopes are presented and summarized. Seasonally, the water table at Jackson Hole Airport was lowest in early spring and reached its peak in July, with an increase of 12 to 14 feet between April and July 2009. Groundwater flow was predominantly horizontal but had the hydraulic potential for downward flow. The direction of groundwater flow was from the northeast to the west-southwest. Horizontal groundwater velocities within the Snake River alluvial aquifer at the airport were estimated to be about 26 to 66 feet per day. This indicates that the traveltime from the farthest upgradient well to the farthest downgradient well was approximately 53 to 138 days. This estimate only describes the movement of groundwater because some solutes may move at a rate much slower than groundwater flow through the aquifer. The quality of the water in the alluvial aquifer generally was considered good. The alluvial aquifer was a fresh, hard to very hard, calcium carbonate type water. No constituents were detected at concentrations exceeding U.S. Environmental Protection Agency Maximum Contaminant Levels, and no anthropogenic compounds were detected at concentrations greater than laboratory reporting levels. The quality of groundwater in the alluvial aquifer generally was suitable for domestic and other uses; however, dissolved iron and manganese were detected at concentrations exceeding the U.S. Environmental Protection Agency Secondary Maximum Contaminant Levels for drinking water in two monitoring wells. These secondary standards are esthetic guidelines only and are nonenforceable. Iron and manganese are likely both natural components of the geologic materials in the area and may have become mobilized in the aquifer due to reduction/oxidation (redox) processes. Additionally, measurements of dissolved-oxygen concentrations and analyses of major ions and nutrients indicate reducing conditions exist at two of the seven wells sampled. Reducing conditions in an otherwise oxic aquifer system are indicative of an upgradient or in-situ source of organic carbon. The nature of the source of organic carbon at the airport could not be determined. View report for unabridged abstract.

Field Evaluation of the Restorative Capacity of the Aquifer Downgradient of a Uranium In-Situ Recovery Mining Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reimus, Paul William

A two-part field study was conducted in Smith Ranch-Highland in-situ recovery (ISR) near Douglas, Wyoming, to evaluate the restorative capacity of the aquifer downgradient (i.e., hydrologically downstream) of a Uranium ISR mining site with respect to the transport of uranium and other potential contaminants in groundwater after mining has ceased. The study was partially conducted by checking the Uranium content and the alkalinity of separate wells, some wells had been restored and others had not. A map and in-depth procedures of the study are included.

Capstone Report on the Application, Monitoring, and Performance of Permeable Reactive Barriers for Ground-Water Remediation: Volume 1: Performance Evaluations at Two Sites

DTIC Science & Technology

2003-08-01

sepiolite , Mg 4 (OH) 2 Si 6 O 15 ·H 2 O...EC050801-3-5 EC050801-3-3 EC050801-3-2 EC050801-3-1 In te n si ty degrees 2-theta In te n si ty In te n si ty downgradient edge upgradient edge In te n...400 b ic a rb o n a te , m g /L 0 2 4 6 8 10 12 14 16 si lic a , m g /L Figure 4.12 Average (± 1 s.d.) concentrations of Na, K , Ca,

Design, installation, and performance of a multi-layered permeable reactive barrier, Los Alamos National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaszuba, J. P.; Longmire, P. A.; Strietelmeier, E. A.

2004-01-01

A multi-layered permeable reactive barrier (PRB) has been installed in Mortandad Canyon, on the Pajarito Plateau in the north-central part of LANL, to demonstrate in-situ treatment of a suite of contaminants with dissimilar geochemical properties. The PRB will also mitigate possible vulnerabilities from downgradient contaminant movement within alluvial and deeper perched groundwater. Mortandad Canyon was selected as the location for this demonstration project because the flow of alluvial groundwater is constrained by the geology of the canyon, a large network of monitoring wells already were installed along the canyon reach, and the hydrochemistry and contaminant history of the canyon ismore » well-documented. The PRB uses a funnel-and-gate system with a series of four reactive media cells to immobilize or destroy contaminants present in alluvial groundwater, including strontium-90, plutonium-238,239,240, americium-241, perchlorate, and nitrate. The four cells, ordered by sequence of contact with the groundwater, consist of gravel-sized scoria (for colloid removal); phosphate rock containing apatite (for metals and radionuclides); pecan shells and cotton seed admixed with gravel (bio-barrier, to deplete dissolved oxygen and destroy potential RCRA organic compounds, nitrate and perchlorate); and limestone (pH buffering and anion adsorption). Design elements of the PRB are based on laboratory-scale treatability studies and on a field investigation of hydrologic, geochemical, and geotechnical parameters. The PRB was designed with the following criteria: 1-day residence time within the biobarrier, 10-year lifetime, minimization of surface water infiltration and erosion, optimization of hydraulic capture, and minimization of excavated material requiring disposal. Each layer has been equipped with monitoring wells or ports to allow sampling of groundwater and reactive media, and monitor wells are located immediately adjacent to the up- and down-gradient perimeter of the engineered structure. Groundwater sampling upgradient, within, and downgradient of the PRB took place from May through August 2003. Concentrations of strontium-90 have diminished by 80% and 40% within the central portion of the phosphate rock (apatite) and bio-barrier cells, respectively. Higher concentrations of this radionuclide occur in groundwater near the north and south perimeters of the two cells. The non-uniform distribution of strontium-90 may result from varying residence time and saturated thickness of pore water. Initial concentrations of nitrate (8-12 parts per million or ppm as nitrate) and perchlorate (0.035 ppm) have been reduced in the phosphate rock and bio-barrier cells to concentrations that are less than method detection limits (0.01 and 0.002 ppm, respectively). Initial microbial analyses suggest the presence of both dissimilatory perchlorate- and nitrate-reducing bacterial populations, along with production of acetate and propionate, and decreasing dissolved oxygen and pH. The dominant group of perchlorate reducers consists of members of the previously described Dechloromonas genus, in the beta subclass of the Proteobacteria, which together with the Dechlorosoma genus are considered to be the dominant genera in circum-neutral mesophilic environments. Groundwater flow through the multiple PRB is taking place at a very slow rate based on similar concentrations of nitrate, perchlorate, chlorate, and chlorite in the upgradient well MCO-4B and downgradient well MCO-5. Concentrations of these constituents also increase within the limestone cell. Decreased precipitation due to extreme drought is probably responsible for decreasing saturated thickness within both the alluvium and PRB, resulting in stagnant conditions. Varying distributions of ammonium, nitrate, sulfate, iron, and manganese within the phosphate rock, bio-barrier, and limestone cells also support this hypothesis.« less

Patterns and age distribution of ground-water flow to streams

USGS Publications Warehouse

Modica, E.; Reilly, T.E.; Pollock, D.W.

1997-01-01

Simulations of ground-water flow in a generic aquifer system were made to characterize the topology of ground-water flow in the stream subsystem and to evaluate its relation to deeper ground-water flow. The flow models are patterned after hydraulic characteristics of aquifers of the Atlantic Coastal Plain and are based on numerical solutions to three-dimensional, steady-state, unconfined flow. The models were used to evaluate the effects of aquifer horizontal-to-vertical hydraulic conductivity ratios, aquifer thickness, and areal recharge rates on flow in the stream subsystem. A particle tracker was used to determine flow paths in a stream subsystem, to establish the relation between ground-water seepage to points along a simulated stream and its source area of flow, and to determine ground-water residence time in stream subsystems. In a geometrically simple aquifer system with accretion, the source area of flow to streams resembles an elongated ellipse that tapers in the downgradient direction. Increased recharge causes an expansion of the stream subsystem. The source area of flow to the stream expands predominantly toward the stream headwaters. Baseflow gain is also increased along the reach of the stream. A thin aquifer restricts ground-water flow and causes the source area of flow to expand near stream headwaters and also shifts the start-of-flow to the drainage basin divide. Increased aquifer anisotropy causes a lateral expansion of the source area of flow to streams. Ground-water seepage to the stream channel originates both from near- and far-recharge locations. The range in the lengths of flow paths that terminate at a point on a stream increase in the downstream direction. Consequently, the age distribution of ground water that seeps into the stream is skewed progressively older with distance downstream. Base flow ia an integration of ground water with varying age and potentially different water quality, depending on the source within the drainage basin. The quantitative results presented indicate that this integration can have a wide and complex residence time range and source distribution.

Use of tree-ring chemistry to document historical ground-water contamination events

USGS Publications Warehouse

Vroblesky, Don A.; Yanosky, Thomas M.

1990-01-01

The annual growth rings of tulip trees (Liriodendron tulipifera L.) appear to preserve a chemical record of ground-water contamination at a landfill in Maryland. Zones of elevated iron and chlorine concentrations in growth rings from trees immediately downgradient from the landfill are closely correlated temporally with activities in the landfill expected to generate iron and chloride contamination in the ground water. Successively later iron peaks in trees increasingly distant from the landfill along the general direction of ground-water flow imply movement of iron-contaminated ground water away from the landfill. The historical velocity of iron movement (2 to 9 m/yr) and chloride movement (at least 40 m/yr) in ground water at the site was estimated from element-concentration trends of trees at successive distances from the landfill. The tree-ring-derived chloride-transport velocity approximates the known ground-water velocity (30 to 80 m/yr). A minimum horizontal hydraulic conductivity (0.01 to .02 cm/s) calculated from chloride velocity agrees well with values derived from aquifer tests (about 0.07 cm/s) and from ground-water modeling results (0.009 to 0.04 cm/s).

Microbial characterization of nitrification in a shallow, nitrogen-contaminated aquifer, Cape Cod, Massachusetts and detection of a novel cluster associated with nitrifying Betaproteobacteria

USGS Publications Warehouse

Miller, D.N.; Smith, R.L.

2009-01-01

Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage effluent infiltration bed, received treated effluent containing O2 (> 300????M) and NH4+ (51-800????M). The second site was 2.5??km down-gradient near the leading edge of the ammonium zone within the contaminant plume and featured vertical gradients of O2, NH4+, and NO3- (0-300, 0-500, and 100-200????M with depth, respectively). Ammonia- and nitrite-oxidizers enumerated by the culture-based MPN method were low in abundance at both sites (1.8 to 350??g- 1 and 33 to 35,000??g- 1, respectively). Potential nitrifying activity measured in core material in the laboratory was also very low, requiring several weeks for products to accumulate. Molecular analysis of aquifer DNA (nested PCR followed by cloning and 16S rDNA sequencing) detected primarily sequences associated with the Nitrosospira genus throughout the cores at the down-gradient site and a smaller proportion from the Nitrosomonas genus in the deeper anoxic, NH4+ zone at the down-gradient site. Only a single Nitrosospira sequence was detected beneath the infiltration bed. Furthermore, the majority of Nitrosospira-associated sequences represent an unrecognized cluster. We conclude that an uncharacterized group associated with Nitrosospira dominate at the geochemically stable, down-gradient site, but found little evidence for Betaproteobacteria nitrifiers beneath the infiltration beds where geochemical conditions were more variable.

Isotopic evidence for reductive immobilization of uranium across a roll-front mineral deposit

DOE PAGES

Brown, Shaun T.; Basu, Anirban; Christensen, John N.; ...

2016-05-20

We use uranium (U) isotope ratios to detect and quantify the extent of natural U reduction in groundwater across a roll front redox gradient. Our study was conducted at the Smith Ranch-Highland in situ recovery (ISR) U mine in eastern Wyoming, USA, where economic U deposits occur in the Paleocene Fort Union formation. To evaluate the fate of aqueous U in and adjacent to the ore body, we investigated the chemical composition and isotope ratios of groundwater samples from the roll-front type ore body and surrounding monitoring wells of a previously mined area. The 238U/ 235U of groundwater varies bymore » approximately 3‰ and is correlated with U concentrations. Fluid samples down-gradient of the ore zone are the most depleted in 238U and have the lowest U concentrations. Activity ratios of 234U/ 238U are ~5.5 up-gradient of the ore zone, ~1.0 in the ore zone, and between 2.3 and 3.7 in the down-gradient monitoring wells. High-precision measurements of 234U/ 238U and 238U/ 235U allow for development of a conceptual model that evaluates both the migration of U from the ore body and the extent of natural attenuation due to reduction. We find that the premining migration of U down-gradient of the delineated ore body is minimal along eight transects due to reduction in or adjacent to the ore body, whereas two other transects show little or no sign of reduction in the down-gradient region. Lastly, these results suggest that characterization of U isotopic ratios at the mine planning stage, in conjunction with routine geochemical analyses, can be used to identify where more or less postmining remediation will be necessary.« less

Microbial characterization of nitrification in a shallow, nitrogen-contaminated aquifer, Cape Cod, Massachusetts and detection of a novel cluster associated with nitrifying Betaproteobacteria

NASA Astrophysics Data System (ADS)

Miller, Daniel N.; Smith, Richard L.

2009-01-01

Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage effluent infiltration bed, received treated effluent containing O 2 (> 300 µM) and NH 4+ (51-800 µM). The second site was 2.5 km down-gradient near the leading edge of the ammonium zone within the contaminant plume and featured vertical gradients of O 2, NH 4+, and NO 3- (0-300, 0-500, and 100-200 µM with depth, respectively). Ammonia- and nitrite-oxidizers enumerated by the culture-based MPN method were low in abundance at both sites (1.8 to 350 g - 1 and 33 to 35,000 g - 1 , respectively). Potential nitrifying activity measured in core material in the laboratory was also very low, requiring several weeks for products to accumulate. Molecular analysis of aquifer DNA (nested PCR followed by cloning and 16S rDNA sequencing) detected primarily sequences associated with the Nitrosospira genus throughout the cores at the down-gradient site and a smaller proportion from the Nitrosomonas genus in the deeper anoxic, NH 4+ zone at the down-gradient site. Only a single Nitrosospira sequence was detected beneath the infiltration bed. Furthermore, the majority of Nitrosospira-associated sequences represent an unrecognized cluster. We conclude that an uncharacterized group associated with Nitrosospira dominate at the geochemically stable, down-gradient site, but found little evidence for Betaproteobacteria nitrifiers beneath the infiltration beds where geochemical conditions were more variable.

Ground and surface water developmental toxicity at a municipal landfill--Description and weather-related variation

USGS Publications Warehouse

Bruner, M.A.; Rao, M.; Dumont, J.N.; Hull, M.; Jones, T.; Bantle, J.A.

1998-01-01

Contaminated groundwater poses a significant health hazard and may also impact wildlife such as amphibians when it surfaces. Using FETAX (Frog Embryo Teratogenesis Assay-Xenopus), the developmental toxicity of ground and surface water samples near a closed municipal landfill at Norman, OK, were evaluated. The groundwater samples were taken from a network of wells in a shallow, unconfined aquifer downgradient from the landfill. Surface water samples were obtained from a pond and small stream adjacent to the landfill. Surface water samples from a reference site in similar habitat were also analyzed. Groundwater samples were highly toxic in the area near the landfill, indicating a plume of toxicants. Surface water samples from the landfill site demonstrated elevated developmental toxicity. This toxicity was temporally variable and was significantly correlated with weather conditions during the 3 days prior to sampling. Mortality was negatively correlated with cumulative rain and relative humidity. Mortality was positively correlated with solar radiation and net radiation. No significant correlations were observed between mortality and weather parameters for days 4–7 preceding sampling.

Application of Monte Carlo Methods to Perform Uncertainty and Sensitivity Analysis on Inverse Water-Rock Reactions with NETPATH

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGraw, David; Hershey, Ronald L.

Methods were developed to quantify uncertainty and sensitivity for NETPATH inverse water-rock reaction models and to calculate dissolved inorganic carbon, carbon-14 groundwater travel times. The NETPATH models calculate upgradient groundwater mixing fractions that produce the downgradient target water chemistry along with amounts of mineral phases that are either precipitated or dissolved. Carbon-14 groundwater travel times are calculated based on the upgradient source-water fractions, carbonate mineral phase changes, and isotopic fractionation. Custom scripts and statistical code were developed for this study to facilitate modifying input parameters, running the NETPATH simulations, extracting relevant output, postprocessing the results, and producing graphs and summaries.more » The scripts read userspecified values for each constituent’s coefficient of variation, distribution, sensitivity parameter, maximum dissolution or precipitation amounts, and number of Monte Carlo simulations. Monte Carlo methods for analysis of parametric uncertainty assign a distribution to each uncertain variable, sample from those distributions, and evaluate the ensemble output. The uncertainty in input affected the variability of outputs, namely source-water mixing, phase dissolution and precipitation amounts, and carbon-14 travel time. Although NETPATH may provide models that satisfy the constraints, it is up to the geochemist to determine whether the results are geochemically reasonable. Two example water-rock reaction models from previous geochemical reports were considered in this study. Sensitivity analysis was also conducted to evaluate the change in output caused by a small change in input, one constituent at a time. Results were standardized to allow for sensitivity comparisons across all inputs, which results in a representative value for each scenario. The approach yielded insight into the uncertainty in water-rock reactions and travel times. For example, there was little variation in source-water fraction between the deterministic and Monte Carlo approaches, and therefore, little variation in travel times between approaches. Sensitivity analysis proved very useful for identifying the most important input constraints (dissolved-ion concentrations), which can reveal the variables that have the most influence on source-water fractions and carbon-14 travel times. Once these variables are determined, more focused effort can be applied to determining the proper distribution for each constraint. Second, Monte Carlo results for water-rock reaction modeling showed discrete and nonunique results. The NETPATH models provide the solutions that satisfy the constraints of upgradient and downgradient water chemistry. There can exist multiple, discrete solutions for any scenario and these discrete solutions cause grouping of results. As a result, the variability in output may not easily be represented by a single distribution or a mean and variance and care should be taken in the interpretation and reporting of results.« less

Land management impacts on dairy-derived dissolved organic carbon in ground water

USGS Publications Warehouse

Chomycia, J.C.; Hernes, P.J.; Harter, T.; Bergamaschi, B.A.

2008-01-01

Dairy operations have the potential to elevate dissolved organic carbon (DOC) levels in ground water, where it may interact with organic and inorganic contaminants, fuel denitrification, and may present problems for drinking water treatment. Total and percent bioavailable DOC and total and carbon-specific trihalomethane (THM) formation potential (TTHMFP and STHMFP, respectively) were determined for shallow ground water samples from beneath a dairy farm in the San Joaquin Valley, California. Sixteen wells influenced by specific land management areas were sampled over 3 yr. Measured DOC concentrations were significantly elevated over the background as measured at an upgradient monitoring well, ranging from 13 to 55 mg L-1 in wells downgradient from wastewater ponds, 8 to 30 mg L-1 in corral wells, 5 to 12 mg L-1 in tile drains, and 4 to 15 mg L-1 in wells associated with manured fields. These DOC concentrations were at the upper range or greatly exceeded concentrations in most surface water bodies used as drinking water sources in California. DOC concentrations in individual wells varied by up to a factor of two over the duration of this study, indicating a dynamic system of sources and degradation. DOC bioavailability over 21 d ranged from 3 to 10%, comparable to surface water systems and demonstrating the potential for dairy-derived DOC to influence dissolved oxygen concentrations (nearly all wells were hypoxic to anoxic) and denitrification. TTHMFP measurements across all management units ranged from 141 to 1731 ??g L-1, well in excess of the maximum contaminant level of 80 ??g L-1 established by the Environmental Protection Agency. STHMFP measurements demonstrated over twofold variation (???4 to ???8 mmol total THM/mol DOC) across the management areas, indicating the dependence of reactivity on DOC composition. The results indicate that land management strongly controls the quantity and quality of DOC to reach shallow ground water and hence should be considered when managing ground water resources and in any efforts to mitigate contamination of ground water with carbon-based contaminants, such as pesticides and pharmaceuticals. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Saline contamination of soil and water on Pawnee tribal trust land, eastern Payne County, Oklahoma

USGS Publications Warehouse

Runkle, Donna L.; Abbott, Marvin M.; Lucius, Jeffrey E.

2001-01-01

The Bureau of Land Management reported evidence of saline contamination of soils and water in Payne County on Pawnee tribal trust land. Representatives of the Bureau of Land Management and U.S. Geological Survey inspected the site, in September 1997, and observed dead grass, small shrubs, and large trees near some abandoned oil production wells, a tank yard, an pit, and pipelines. Soil and bedrock slumps and large dead trees were observed near a repaired pipeline on the side of the steep slope dipping toward an unnamed tributary of Eagle Creek. The U.S. Geological Survey, in cooperation with the Bureau of Land Management, initiated an investigation in March 1998 to examine soil conductance and water quality on 160 acres of Pawnee tribal trust land where there was evidence of saline contamination and concern about saline contamination of the Ada Group, the shallowest freshwater aquifer in the area. The proximity of high specific conductance in streams to areas containing pipeline spill, abandoned oil wells, the tank yard, and the pit indicates that surface-water quality is affected by production brines. Specific conductances measured in Eagle Creek and Eagle Creek tributary ranged from 1,187 to 10,230 microsiemens per centimeter, with the greatest specific conductance measured downgradient of a pipeline spill. Specific conductance in an unnamed tributary of Salt Creek ranged from 961 to 11,500 microsiemens per centimeter. Specific conductance in three ponds ranged from 295 to 967 microsiemens per centimeter, with the greatest specific conductance measured in a pond located downhill from the tank yard and the abandoned oil well. Specific conductance in water from two brine storage pits ranged from 9,840 to 100,000 microsiemens per centimeter, with water from the pit near a tank yard having the greater specific conductance. Bartlesville brine samples from the oil well and injection well have the greatest specific conductance, chloride concentration, and dissolved solids concentrations, and plot the furthest from meteoric water on a graph of 8 deuterium and d 18oxygen. Waterflooding of the Bartlesville sand in the study area started in 1957 and continued until 1998. Waterflooding is the process of injecting brine water under pressure to drive the remaining oil to the production wells. The high dissolved solids concentration samples from observation wells 1, 3B, 5,7, and 8 could result from mixing of the Bartlesville brine from the waterfiood with meteoric water.

Reconnaissance of the hydrology, water quality, and sources of bacterial and nutrient contamination in the Ozark Plateaus aquifer system and Cave Springs Branch of Honey Creek, Delaware County, Oklahoma, March 1999-March 2000

USGS Publications Warehouse

Schlottmann, Jamie L.; Tanner, Ralph S.; Samadpour, Mansour

2000-01-01

A reconnaissance investigation of hydrology and water quality was conducted to evaluate possible sources of bacteria and nutrient contamination in the Cave Springs Branch basin and the underlying karstic Ozark Plateau aquifer system. Objectives were to: (1) determine the directions of ground-water flow in the basin and determine whether Cave Springs Branch interacts with ground water, (2) compare water quality in Cave Springs Branch with water quality in nearby wells to determine whether the stream is contaminating nearby wells, and (3) determine sources of fecal coliform bacteria and nitrate contamination in Cave Springs Branch and ground water. Potential sources of bacteria and nitrate in the area include cultivated agriculture, cow and horse on pasture, poultry production, households, and wildlife. Presence of fecal coliform and fecal streptococcal bacteria directly indicate fecal contamination and the potential for the presence of other pathogenic organisms in a water supply. Nitrate in drinking water poses health risks and may indicate the presence of additional contaminants. Fecal coliform bacteria colony counts were least in wells, intermediate in the poultry-processing plant wastewater outfall and Honey Creek above the confluence with Cave Springs Branch, and greatest in Cave Springs Branch. Bacteria strains and resistance to antibiotics by some bacteria indicate that livestock may have been sources of some bacteria in the water samples. Multiple antibiotic resistances were not present in the isolates from the water samples, indicating that the bacteria may not be from human or poultry sources. Ribotyping indicates that Escherichia coli bacteria in water samples from the basin were from bird, cow, horse, dog, deer, and human sources. The presence of multiple ribotypes from each type of animal source except bird indicates that most of the bacteria are from multiple populations of source animals. Identifiable sources of bacteria in Cave Springs Branch at the state line were dominantly cow and horse with one ribotype from bird. Escherichia coli was detected in only one well sample. Bacterial ribotypes in water from that upgradient well indicated human and dog feces as sources for bacteria, and that on site wastewater treatment may not always be adequate in these highly permeable soils. Greater concentrations of nitrate in Cave Springs Branch and O'Brien Spring relative to the poultry-processing plant wastewater outfall may be due, in part, to conversion of ammonia from poultry processing plant wastewater. The poultry-processing plant wastewater outfall sample collected in March 2000 contained greater concentrations of ammonia and total organic nitrogen plus ammonia than the spring, stream, and well samples collected during August 1999. Cave Springs Branch and Honey Creek contributed approximately equal loads of nitrogen to Honey Creek below the confluence and the greatest loads of nitrogen were introduced to Cave Springs Branch by the poultry processing plant wastewater outfall and O'Brien Spring. Nitrate concentrations in upgradient well samples ranged from 0.38 to 4.60 milligrams per liter, indicating that there are sources of ground-water nitrogen other than Cave Springs Branch, such as animal waste, fertilizer, or human waste. Nitrogen compounds in water from wells downgradient of Cave Springs Branch may be from Cave Springs Branch, fertilizers, animal waste, or human waste.

Intragranular diffusion--An important mechanism influencing solute transport in clastic aquifers?

USGS Publications Warehouse

Vroblesky, Don A.; Yanosky, Thomas M.

1990-01-01

The annual growth rings of tulip trees (Liriodendron tulipifera L.) appear to preserve a chemical record of ground-water contamination at a landfill in Maryland. Zones of elevated iron and chlorine concentrations in growth rings from trees immediately downgradient from the landfill are closely correlated temporally with activities in the landfill expected to generate iron and chloride contamination in the ground water. Successively later iron peaks in trees increasingly distant from the landfill along the general direction of ground-water flow imply movement of iron-contaminated ground water away from the landfill. The historical velocity of iron movement (2 to 9 m/yr) and chloride movement (at least 40 m/yr) in ground water at the site was estimated from element-concentration trends of trees at successive distances from the landfill. The tree-ring-derived chloride-transport velocity approximates the known ground-water velocity (30 to 80 m/yr). A minimum horizontal hydraulic conductivity (0.01 to .02 cm/s) calculated from chloride velocity agrees well with values derived from aquifer tests (about 0.07 cm/s) and from ground-water modeling results (0.009 to 0.04 cm/s).

Areal extent of petroleum-related compounds from a gasoline and diesel-fuel leak in ground water at a site in Yakima, Washington, 1984-89

USGS Publications Warehouse

Wagner, R.J.

1995-01-01

A gasoline and diesel-fuel leak was discovered in the early 1980's at a service station in Yakima, Washington, and an attempt to recover the flee-floating petroleum product was unsuccessful. From 1984 through 1989, data were collected from observation wells drilled near the site of the leak and from nearby domestic wells during three separate studies. Between February 1985 and November 1986, benzene, toluene, xylenes, and other soluble compounds of petroleum origin were found at concentrations that exceeded standards for drinking water in all samples from observation wells within 300 feet of the service station. These compounds also were found in smaller concentrations in some samples from domestic wells as far as 1,500 feet downgradient of the service station. Concentrations of these soluble compounds in ground-water samples collected in March 1989 had decreased, and areal distribution of the compounds was smaller than when monitoring began in 1984.

Geohydrologic evaluation of a landfill in a coastal area, St Petersburg, Florida

USGS Publications Warehouse

Hutchinson, C.B.; Stewart, Joseph W.

1978-01-01

The 250-acre Toytown landfill site is in a poorly-drained area in coastal Pinellas County, Florida. Average altitude of land surface at the landfill is less than 10 feet. About 1000 tons of solid waste and about 200,000 gallons of digested sewage sludge are disposed of daily at the landfill. The velocity of ground-water flow through the 23-foot thick surficial aquifer northeast from the landfill toward Old Tampa Bay probably ranges from 1 to 10 feet per year, and downward velocity through the confining bed is about 0.00074 foot per day. The horizontal and vertical flow velocities indicate that leachate moves slowly downgradient, and that leachate has not yet seeped through the confining bed after 12 years of landfill operation. Untreated surface run-off from the site averages about 15 inches per year, and ground-water outflow averages about 3.3 inches per year. The Floridan aquifer is used as a limited source of water for domestic supply in this area. (Woodard-USGS)

Potential Aquifer Vulnerability in Regions Down-Gradient from ...

EPA Pesticide Factsheets

Sandstone-hosted roll-front uranium ore deposits originate when U(VI) dissolved in groundwater is reduced and precipitated as insoluble U(IV) minerals. Groundwater redox geochemistry, aqueous complexation, and solute migration are instrumental in leaching uranium from source rocks and transporting it in low concentrations to a chemical redox interface where it is deposited in an ore zone typically containing the uranium minerals uraninite, pitchblende, and/or coffinite; various iron sulfides; native selenium; clays; and calcite. In situ recovery (ISR) of these uranium ores is a process of contacting the uranium mineral deposit with leaching (lixiviant) fluids via injection of the lixiviant into wells drilled into the subsurface aquifer that hosts uranium ore, while other extraction wells pump the dissolved uranium after dissolution of the uranium minerals. Environmental concerns during and after ISR include water quality impacts from: 1) potential excursions of leaching solutions away from the injection zone into down-dip, underlying, or overlying aquifers; 2) potential migration of uranium and its decay products (e.g., Ra, Rn, Pb); and, 3) potential migration of redox-sensitive trace metals (e.g., Fe, Mn, Mo, Se, V), metalloids (e.g., As), and anions (e.g., sulfate). This review describes the geochemical processes that control roll-front uranium transport and fate in groundwater systems, identifies potential aquifer vulnerabilities to ISR operations, identifies

Large-scale redox plume in glaciofluvial deposits due to sugar-factory wastes and wastewater at Aarberg, Switzerland

NASA Astrophysics Data System (ADS)

Wersin, P.; Abrecht, J.; Höhener, P.

2001-06-01

The sugar factory at Aarberg, Switzerland, has processed about 18×106 metric tons of sugar beets in the last 100 years. This has been accompanied by releases of dissolved organic carbon to the groundwater, induced both by direct wastewater disposal until 1964 and by ongoing leakage from solid-waste deposits. Downgradient in the groundwater of the glaciofluvial aquifer, depletion of oxygen concentrations accompanied by low nitrate, high ammonium, dissolved Mn(II) and Fe(II) concentrations are observed. This study was aimed at developing a quantitative comprehension of theimpact of the leaking waste deposits on biogeochemical processes in the aquifer and on groundwater quality. The study includes a review of historical information, a survey of the hydrogeochemistry in the aquifer, the characterisation of river-water infiltration rates with the radon method, establishment of a mass-balance model based on a numerical flow and transport model, and application of a stable-carbon-isotope method to show biodegradation of sugar-waste deposits in the aquifer. The investigations demonstrate that present emissions from waste deposits would not lead to the consumption of all the O2 in the aquifer. The present occurrence of anoxic groundwater conditions is explained as a result of the long history of waste loading.

Application of Analysis and Modeling for Surface Water-Ground Water System: Preliminary Study of Artificial Recharge in Jeju Island, Korea

NASA Astrophysics Data System (ADS)

Kim, Y.; Koo, M.; Lee, K.; Ko, K.; Barry, J. M.

2008-12-01

The primary goal of this study is to secure sustainable groundwater resources with application of the analysis and modeling of coupled surface water-groundwater system to Jeju Island in the form of artificial recharge. Artificial recharge technology is a feasible method to augment groundwater resources in Jeju Island, Korea. Jeju-friendly Aquifer Recharge Technology (J-ART) that will be developed in this study is a technology for securing sustainable water resources by capturing ephemeral stream water with no interference in the environment such as natural recharge or eco-system, capturing the water in the reservoirs, recharging it through designed borehole after appropriate treatment, and then making it to be used at down-gradient production wells. Precipitation pattern in the study area is shifting to more sparsely-distributed and heavier rain type in summer season which reduces infiltration and/or groundwater recharge but increases runoff and flash flood on stream. Stream water as a source for J-ART is available only a few times a year since the stream bed is highly feasible to be percolated. To characterize quantitatively stream water, automatic temporal data collection system for water level, water velocity, and water qualities of total 8 parameters including temperature, water depth, pH, EC, DO, turbidity, NO3-N and Cl-. Characterizing groundwater flow from recharge area to discharge area should be achieved to evaluate the efficiency of J-ART. Jeju volcanic island has very thick unsaturated zone which is approximately 50 percent of the elevation on which it is. This hydrogeological property is good to inject source water through unsaturated zone to increase transport time, to get main basal aquifer, and to naturally filter the injected water during the transport. However, characterizing groundwater flow through the thick unsaturated zone with repeatedly overlapping permeable/impermeable layers would be a challenge. Estimation method of the infiltration velocity of soil water, groundwater age dating, and evaluation method for groundwater flow/circulation using stable isotopes are developed to evaluate artificial recharge. Input parameters for groundwater flow model are collected and analyzed quantitatively to develop model for simulating groundwater flow and thermal transport during artificial recharge. Self-potential survey method is reviewed theoretically as a geophysical evaluation method to characterize unsaturated flow during artificial recharge.

Health assessment for Garden State Cleaners Company, Buena Borough, Atlantic City, New Jersey, Region 2. CERCLIS No. NJD053280160. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-09-28

The Garden State Cleaners Company is a dry cleaning establishment located in Buena Borough, New Jersey. Contaminated wastewater from on-site operations was routinely discharged to on-site soils. Analytical data has described significant soil and ground-water contamination from tetrachloroethylene (PCE) and other volatile organic compounds. Ground-water contamination downgradient (to the south) of the site has required the recommended closing of private wells and the installation of a municipal water supply system. An Administrative Order and Notice of Civil Administrative Penalty Assessment (AO and PSO) were issued to Garden State Cleaners in December 1985, requiring GSC to perform a full RI/FS. Municipalmore » water supplies have been made available to affected residens, but utilization is elective. The site was included on the NPL list in March 1989 and is currently ranked 105 of 108 sites in New Jersey. ATSDR and NJDOH consider the Garden State Cleaners site to be of public health concern. The site is being considered for follow-up health study or evaluation.« less

IN SITU OXIDATION AND ASSOCIATED MASS-FLUX-REDUCTION/MASS-REMOVAL BEHAVIOR FOR SYSTEMS WITH ORGANIC LIQUID LOCATED IN LOWER-PERMEABILITY SEDIMENTS

PubMed Central

Marble, Justin C.; Carroll, Kenneth C.; Janousek, Hilary; Brusseau, Mark L.

2010-01-01

The effectiveness of permanganate for in situ chemical oxidation of organic liquid (trichloroethene) trapped in lower-permeability (K) zones located within a higher-permeability matrix was examined in a series of flow-cell experiments. The permanganate solution was applied in both continuous and pulsed-injection modes. Manganese-oxide precipitation, as confirmed by use of SEM-EDS, occurred within, adjacent to, and downgradient of the lower-K zones, reflective of trichloroethene oxidation. During flow interruptions, precipitate formed within the surrounding higher-permeability matrix, indicating diffusive flux of aqueous-phase trichloroethene from the lower-K zones. The impact of permanganate treatment on mass flux behavior was examined by conducting water floods after permanganate injection. The results were compared to those of water-flood control experiments. The amount of water flushing required for complete contaminant mass removal was reduced for all permanganate treatments for which complete removal was characterized. However, the nature of the mass-flux-reduction/mass-removal relationship observed during water flooding varied as a function of the specific permanganate treatment. PMID:20685008

Biogeochemical assessment of natural attenuation of JP-4-contaminated ground water in the presence of fluorinated surfactants.

PubMed

Levine, A D; Libelo, E L; Bugna, G; Shelley, T; Mayfield, H; Stauffer, T B

1997-12-22

The biogeochemistry of the natural attenuation of petroleum-contaminated ground water was investigated in a field study. The focus of the study was a fire training site located on Tyndall Air Force Base in Florida. The site has been used by the Air Force for approximately 11 years in fire fighting exercises. An on-site above-ground tank of JP-4 provided fuel for setting controlled fires for the exercises. Various amounts of water and aqueous film forming foams (AFFF) were applied to extinguish the fires. The sources of contamination included leaks from pipelines transporting the fuel, leaks from an oil/water separator and runoff and percolation from the fire fighting activities. Previous investigations had identified jet fuel contamination at the site, however, no active remediation efforts have been conducted to date. The goal of this study was to use biogeochemical monitoring data to delineate redox zones within the site and to identify evidence of natural attenuation of JP-4 contamination. In addition to identifying several hydrocarbon metabolites, fluorinated surfactants (AFFF) were detected down-gradient of the hydrocarbon plume.

Use of chlorine-36 to determine regional-scale aquifer dispersivity, eastern Snake River Plain aquifer, Idaho/USA

USGS Publications Warehouse

Cecil, L.D.; Welhan, J.A.; Green, J.R.; Grape, S.K.; Sudicky, E.R.

2000-01-01

Chlorine-36 (36Cl) derived from processed nuclear waste that was disposed at the US Department of Energy's Idaho National Engineering and Environmental Laboratory (INEEL) through a deep injection well in 1958, was detected 24-28 yr later in groundwater monitoring wells approximately 26 km downgradient from the source. Groundwater samples covering the period 1966-1995 were selected from the US Geological Survey's archived-sample library at the INEEL and analyzed for 36Cl by accelerator mass spectrometry (AMS). The smaller 36Cl peak concentrations in water from the far-field monitoring wells relative to the input suggest that aquifer dispersivity may be large. However, the sharpness of the 1958 disposal peak of 36Cl is matched by the measured 36Cl concentrations in water from these wells. This implies that a small aquifer dispersivity may be attributed to preferential groundwater flowpaths. Assuming that tracer arrival times at monitoring wells are controlled by preferential flow, a 1-D system-response model was used to estimate dispersivity by comparing the shape of predicted 36Cl-concentration curves to the shape of 36Cl-concentration curves measured in water from these observation wells. The comparisons suggest that a 1-D dispersivity of 5 m provides the best fit to the tracer data. Previous work using a 2-D equivalent porous-media model concluded that longitudinal dispersivity (equivalent to 1-D dispersivity in our model) was 90 m (Ackerman, 1991). A 90 m dispersivity value eliminates the 1958 disposal peak in our model output curves. The implications of the arrival of 36Cl at downgradient monitoring wells are important for three reasons: (1) the arrival times and associated 36Cl concentrations provide quantitative constraints on residence times, velocities, and dispersivities in the aquifer; (2) they help to refine our working hypotheses of groundwater flow in this aquifer and (3) they may suggest a means of estimating the distribution of preferential flowpaths in the aquifer. ?? 2000 Elsevier Science B.V. All rights reserved.

EXEIS Expert Screening and Optimal Extraction/Injection Pumping Systems for Short-Term Plume Immobilization

DTIC Science & Technology

1990-05-01

TT) d head at observation well j which is down-gradient of the contamination source at the end of the modeling period TT, (L). h head at contaminant...period t, (L); =h 1 ,0 i,t h U = upper limit on head at pump i, (L); (h jTT) d = head at each observation well j which is down-gradient of...E) E D.i j k qt k 1 . . (30)f~q = r~~t ~ I I , j ,k qt-k+l.................(0 i=1 k=1 where: D . - ~ ~ [ft(Qo)A i ,kS dt + fs(Qo)P i j ,k’ dS

Geochemical and hydrologic controls on phosphorus transport in a sewage-contaminated sand and gravel aquifer near Ashumet Pond, Cape Cod, Massachusetts

USGS Publications Warehouse

Walter, D.A.; Rea, B.A.; Stollenwerk, K.G.; Savoie, Jennifer G.

1995-01-01

The disposal of secondarily treated sewage onto rapid infiltration sand beds at the Massachusetts Military Reservation, Cape Cod, Massachusetts, has created a sewage plume in the underlying sand and gravel aquifer; the part of the\\x11sewage plume that contains dissolved phosphorus extends about 2,500 feet downgradient of the sewage-disposal beds. A part of the plume that\\x11contains nearly 2 milligrams per liter of phosphorus currently (1993) discharges into Ashumet Pond along about 700 feet of shoreline. The sewage plume discharges from about 59 to about 76 kilograms of phosphorus per year into the pond. Hydraulic-head measurements indicate that the north end of Ashumet Pond is a ground-water sink and an increased component of ground-water discharge and phosphorus flux into\\x11the pond occurs at higher water levels. Phosphorus was mobile in ground water in two distinct geochemical environments-an anoxic zone that contains no dissolved oxygen and as much as 25\\x11milligrams per liter of dissolved iron, and a more areally extensive suboxic zone that contains little or no iron, low but detectable dissolved oxygen, and as much as 12 milligrams per liter of dissolved manganese. Dissolved phosphorus is mobile in the suboxic geochemical environment because continued phosphorus loading has filled available sorption sites in the aquifer. Continued disposal of sewage since 1936 has created a large reservoir of sorbed phosphorus that is much greater than the mass of dissolved phosphorus in the ground water; the average ratio of sorbed to dissolved phosphorus in the anoxic and suboxic parts of the sewage plume were 31:1 and 155:1, respectively. Column experiments indicate that phosphorus in the anoxic core of the plume containing dissolved iron may be immobilized within 17 years by sorption and coprecipitation with new iron oxyhydroxides following the cessation of sewage disposal and the introduction of uncontaminated oxygenated ground water into the aquifer in December 1995. Residual oxygen demand associated with sorbed organic compounds and ammonia could retard the movement of oxygenated water into the aquifer. Sorbed phosphorus in the suboxic zone of the aquifer will continue to desorb into the ground water and will remain mobile in the ground water for perhaps hundreds of years. Also, the introduction of uncontaminated water into the aquifer may cause dissolved-phosphorus concentrations in the suboxic zone of the aquifer to increase sharply and remain higher than precessation levels for many years due to the desorption of loosely bound phosphorus. Data from three sampling sites, located along the eastern and western boundaries of the sewage plume and downgradient of abandoned sewage-disposal beds, indicate that ground-water mixing and phosphorus desorption may already be occurring in the aquifer in response to the introduction of uncontaminated recharge water into previously contaminated parts of the aquifer.

National water summary 1986; Hydrologic events and ground-water quality

USGS Publications Warehouse

Moody, David W.; Carr, Jerry E.; Chase, Edith B.; Paulson, Richard W.

1988-01-01

Ground water is one of the most important natural resources of the United States and degradation of its quality could have a major effect on the welfare of the Nation. Currently (1985), ground water is the source of drinking water for 53 percent of the Nation's population and for more than 97 percent of its rural population. It is the source of about 40 percent of the Nation's public water supply, 33 percent of water for irrigation, and 17 percent of freshwater for selfsupplied industries.Ground water also is the source of about 40 percent of the average annual streamflow in the United States, although during long periods of little or no precipitation, ground-water discharges provide nearly all of the base streamflow. This hydraulic connection between aquifers and streams implies that if a persistent pollutant gets into an aquifer, it eventually could discharge into a stream.Information presented in the 1986 National Water Summary clearly shows that the United States has very large amounts of potable ground water available for use. Although naturally occurring constituents, such as nitrate, and human-induced substances, such as synthetic organic chemicals, frequently are detected in ground water, their concentrations usually do not exceed existing Federal or State standards or guidelines for maximum concentrations in drinking water.Troublesome contamination of ground water falls into two basic categories related to the source or sources of the contamination. Locally, high concentrations of a variety of toxic metals, organic chemicals, and petroleum products have been detected in ground water associated with point sources such as wastedisposal sites, storage-tank leaks, and hazardous chemical spills. These types of local problems commonly occur in densely populated urban areas and industrialized areas. Larger, multicounty areas also have been identified where contamination frequently is found in shallow wells. These areas generally are associated with broad-scale, or nonpoint, sources of contamination such as agricultural activities or highdensity domestic waste disposal (septic systems) in urban centers. At present, only a very small percentage of the total volume of potable ground water in the United States is contaminated from both point and nonpoint sources; however, available data, especially data about the occurrence of synthetic organic and toxic substances, generally are inadequate to determine the full extent of ground-water contamination in the Nation's aquifers or to define trends in groundwater quality. Most information about the occurrence of these substances has come from the study of individual sites or areas where contamination had already been detected or suspected.Management and protection of ground water present a major challenge to the Nation. Current and projected costs of detection and cleanup of existing ground-water contamination are staggering and, even so, complete removal of pollutants from ground water in the vicinity of some waste sites might not be technically feasible. At all levels of government, the task of protecting the resource for its most beneficial uses is difficult and controversial.Despite increasing awareness that some of the Nation's ground water is contaminated with a variety of toxic metals, synthetic organic chemicals, radionuclides, pesticides, and other contaminants that might present a long-term risk to human health, public policy towards ground-water protection is still in the formative stages. Despite increasing efforts devoted to ground-water protection by State and Federal regulatory and resource-management agencies, the extent of ground-water contamination is likely to appear to increase over the next few years because more agencies will be searching for evidence of contamination, and they will be using increasingly sensitive analytical procedures. Increased technology and expanded monitoring activities probably will detect the effects of past contamination and land uses on water quality. The significant time lag between a waterquality change in one part of an aquifer system and the effects of that change at a downgradient site, such as a well, results from the generally slow movement of ground water. This lag between cause and observed effect needs to be considered in evaluating the effectiveness of current and future ground-water policies and remedial measures.Conclusive answers to questions about the location, extent, and severity of ground-water contamination, and about trends in ground-water quality, must await further collection and analysis of data from the Nation's aquifers. Generalizations, however, can be made, and the 1986 National Water Summary, which describes the natural quality of ground-water resources in each State and the major contamination problems that have been identified as of 1986, provides a national perspective of the ground-water-quality situation.The 1986 National Water Summary follows the format of previous volumes. It contains three parts, and the contents of each of these parts are highlighted below.

Effects of a remedial system and its operation on volatile organic compound-contaminated ground water, Operable Unit 1, Savage Municipal Well Superfund Site, Milford, New Hampshire, 1998-2004

USGS Publications Warehouse

Harte, Philip T.

2006-01-01

The Savage Municipal Well Superfund site in the Town of Milford, N.H., is underlain by a 0.5-square mile plume of volatile organic compounds (VOCs), mostly tetrachloroethylene (PCE). The plume occurs mostly within a highly transmissive sand and gravel layer, but also extends into underlying till and bedrock. The plume has been divided into two areas called Operable Unit 1 (OU1), which contains the primary source area, and Operable Unit 2 (OU2), which is defined as the extended plume area. PCE concentrations in excess of 100,000 parts per billion (ppb) had been detected in the OU1 area in 1995, indicating a likely Dense Non-Aqueous Phase Liquid (DNAPL) source. In the fall of 1998, the New Hampshire Department of Environmental Services (NHDES) and the U.S. Environmental Protection Agency (USEPA) installed a remedial system in OU1 to contain and capture the dissolved VOC plume. The OU1 remedial system includes a low-permeability barrier wall that encircles the highest detected concentrations of PCE, and a series of injection and extraction wells to contain and remove contaminants. The barrier wall likely penetrates the full thickness of the sand and gravel; in most places, it also penetrates the full thickness of the underlying basal till and sits atop bedrock. Remedial injection and extraction wells have been operating since the spring of 1999 and include a series of interior (inside the barrier wall) injection and extractions wells and exterior (outside the barrier wall) injection and extraction wells. A recharge gallery outside the barrier wall receives the bulk of the treated water and reinjects it into the shallow aquifer. From 1998 to 2004, PCE concentrations decreased by an average of 80 percent at most wells outside the barrier wall. This decrease indicates (1) the barrier wall and interior extraction effectively contained high PCE concentrations inside the wall, (2) other sources of PCE did not appear to be outside of the wall, and (3) ambient ground-water flow in conjunction with the exterior remedial wells effectively remediated most of the dissolved PCE plume outside the wall. The overburden at middle depths (40 to 70 ft below land surface) downgradient from exterior extraction wells showed relatively slow decreases in PCE concentrations compared to other areas outside the barrier wall. Numerical simulation shows extraction caused the formation of a small downgradient slow-velocity zone. Because the ambient ground-water velocities are high (approximately 1 foot per day), temporary termination of extraction at the exterior wells may increase dilution downgradient from the exterior extraction wells. Extraction can also be optimized on the basis of seasonal hydrologic conditions to facilitate exterior well capture from upgradient areas outside of the barrier wall where PCE concentrations are highest. Reductions in concentrations of PCE inside the barrier wall from 1998 to 2003 were minimal near suspected source areas, indicating that the operation of interior remedial wells had not been effective in remediating dissolved PCE or the DNAPL source. Capture of the dissolved PCE plume within the barrier wall by interior extraction wells could be enhanced if operation (injection rates) increased at underutilized interior injection wells, thereby increasing hydraulic gradients.

Assessment of potential for natural attenuation of chlorinated ethenes and ethanes in ground water at a petrochemical reclamation site, Harris County, Texas

USGS Publications Warehouse

Huff, Glenn F.; Braun, Christopher L.; Lee, Roger W.

2000-01-01

Redox conditions in the Numerous Sand Channels Zone beneath a petrochemical reclamation site in Harris County, Texas, range from sulfate reducing to methanogenic as indicated by the presence of methane in ground water and the range of molecular hydrogen concentrations. Assessment of the potential for reductive dechlorination using BIOCHLOR as a screening tool indicated conditions favoring anaerobic degradation of chlorinated organic compounds in the Numerous Sand Channels Zone. Evidence supporting reductive dechlorination includes apparently biogenic cis-1,2-dichloroethene; an increased ratio of 1,2-dichloroethane to 1,1,2-trichloroethane downgradient from the assumed contaminant source area; ethene and methane concentrations greater than background concentrations within the area of the contaminant plume; and a positive correlation of the ratio of ethene to vinyl chloride as a function of methane concentrations. The body of evidence presented in this report argues for hydrogenolysis of trichloroethene to cis-1,2-dichloroethene; of 1,1,2-trichloroethane to 1,2-dichloroethane; and of vinyl chloride to ethene within the Numerous Sand Channels Zone. Simulations using BIOCHLOR yielded apparent first-order decay constants for reductive dechlorination in the sequence Tetrachloroethene --> trichloroethene --> cis-1,2-dichloroethene --> vinyl chloride --> ethene within the range of literature values reported for each compound and apparent first-order decay constants for reductive dechlorination in the sequence 1,1,2-trichloroethane --> 1,2-dichloroethane slightly greater than literature values reported for each compound along the upgradient segment of a simulated ground-water flowpath. Except for vinyl chloride, apparent rates of reductive dechlorination for all simulated species show a marked decrease along the downgradient segment of the simulated ground-water flowpath. Evidence for reductive dechlorination of chlorinated ethenes within the Numerous Sand Channels Zone indicates potential for natural attenuation of chlorinated ethenes. Reductive dechlorination of chlorinated ethanes apparently occurs to a lesser extent, indicating relatively less potential for natural attenuation of chlorinated ethanes. Additional data are needed on the concentrations and distribution of chlorinated ethenes and ethanes in individual fine sand intervals of the Numerous Sand Channels Zone. This information, combined with lower minimum reporting levels for future chloroethane analyses, might enable a more complete and quantitative assessment of the potential for natural attenuation at the site.

Assessment of Drywells as Effective Tools for Stormwater Management and Aquifer Recharge: Results of a Two-Year Field and Numerical Modeling Study

NASA Astrophysics Data System (ADS)

Edwards, E.; Washburn, B.; Harter, T.; Fogg, G. E.; Nelson, C.; Lock, B.; Li, X.

2016-12-01

Drywells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas with low permeability soils or cover. Stormwater runoff that would otherwise be routed to streams or drains in urban areas can be used as a source of aquifer recharge, potentially mitigating the effects of drought and harm to natural water bodies. However, the potential for groundwater contamination caused by urban runoff bypassing surface soil and near surface sediment attenuation processes has prevented more widespread use of drywells as a recharge mechanism. A field study was conducted in Elk Grove, CA, to determine the effects of drywell-induced stormwater infiltration on the local hydrogeologic system. Two drywells 13.5 meters in depth were constructed for the project: one in a preexisting drainage basin fed by residential lots, and one at an industrial site. Both sites were outfitted with vegetated pretreatments, and upgradient and downgradient groundwater monitoring wells. Site stormwater and groundwater were sampled between November, 2014, and May, 2016, and analyzed for contaminants. Results of water quality sampling have been statistically analyzed for trends and used to determine the contaminants of interest and the concentrations of these contaminants in influent stormwater. The fate and transport of these contaminants have been simulated using a 1D variably saturated flow and transport model and site specific parameters to predict long-term effects of stormwater infiltration on the surrounding hydrogeologic system. The potential for remobilization of geogenic heavy metals from changes in subsurface hydrochemistry caused by drywell infiltration have also been assessed. The results of the field study and numerical modeling assessment indicate that the study's drywells do not pose a long-term threat to groundwater quality and may be an effective source of aquifer recharge and tool for urban stormwater management.

Fate and Tranport of MTBE in Clay-Rich Materials

NASA Astrophysics Data System (ADS)

lenczewski, m e

2001-12-01

A recent report by the U.S. Geological Survey identified methyl tert-butyl ether (MTBE), a constituent of reformulated gasoline, as the most common contaminant of urban aquifers in the United States. MTBE has been released into groundwater supplies by leaking underground fuel tanks. In Illinois, it has been found in 26 of the 1,800 public water supplies and although detection was intermittent, levels were high enough to be offensive to users in some Illinois communities. MTBE is also being used in Mexico to solve the problem of air quality; however, it has the potential to harm the drinking water quality in the process. Early research on MTBE considered it resistant to biodegradation and unable to adsorb to soils and sediments. However, recent evidence indicates that biodegradation does occur under certain conditions and that sorption can occur to organic materials. This research project will investigate the biodegradation of MTBE and its sorption to the clay-rich glacial till found in northern Illinois and lacustrine clays found in the Chalco Basin, Mexico City, Mexico whose interaction with MTBE has not previously been studied. The principal hypothesis of this research is that the microorganisms and environmental factors in clay-rich materials will increase the biodegradation and sorption of MTBE as compared to sandy materials. The experiments will simulate a spill of MTBE or downgradient from a gasoline spill. Microcosms and batch isotherm experiments will be used to demonstrate the potential for biodegradation and sorption in these materials; however, laboratory results are not considered reliable estimates of actual field sorption and biodegradation rates. Therefore long-term column experiments will also be conducted in which large sample volumes of material that simulate the heterogeneities naturally observed in the environment. This research will increase understanding of the biodegradation and sorption of MTBE and lay the necessary groundwork to implement the optimal remediation method for sites contaminated by MTBE, helping to ensure a sustainable groundwater resource.

Hydrologic and geochemical approaches for determining ground-water flow components

USGS Publications Warehouse

Hjalmarson, H.W.; Robertson, F.N.

1991-01-01

Lyman Lake is an irrigation-storage reservoir on the Little Colorado River near St. Johns, Arizona. The main sources of water for the lake are streamflow in the Little Colorado River and ground-water inflow from the underlying Coconino aquifer. Two approaches, a hydrologic analysis and a geochemical analysis, were used to compute the quantity of ground-water flow to and from Lyman Lake. Hydrologic data used to calculate a water budget were precipitation on the lake, evaporation from the lake, transpiration from dense vegetation, seepage through the dam, streamflow in and out of the lake, and changes in lake storage. Geochemical data used to calculate the ground-water flow components were major ions, trace elements, and the stable isotopes of hydrogen and oxygen. During the study, the potentiometric level of the Coconino aquifer was above the lake level at the upstream end of the lake and below the lake level at the downstream end. Hydrologic and geochemical data indicate that about 10 percent and 8 percent, respectively, of the water in the lake is ground-water inflow and that about 35 percent of the water in the Little Colorado River 6 miles downgradient from the lake near Salado Springs is ground water. These independent estimates of ground-water flow derived from each approach are in agreement and support a conceptual model of the water budget.

Modern marine sediments as a natural analog to the chemically stressed environment of a landfill

USGS Publications Warehouse

Baedecker, M.J.; Back, W.

1979-01-01

Chemical reactions that occur in landfills are analogous to those reactions that occur in marine sediments. Lateral zonation of C, N, S, O, H, Fe and Mn species in landfills is similar to the vertical zonation of these species in marine sediments and results from the following reaction sequence: (1) oxidation of C, N and S species in the presence of dissolved free oxygen to HCO3-, NO3- and SO2-4; (2) after consumption of molecular oxygen, then NO3- is reduced, and Fe and Mn are solubilized; (3) SO2-4 is reduced to sulfide; and (4) organic compounds become the source of oxygen, and CH4 and NH4+ are formed as fermentation products. In a landfill in Delaware the oxidation potential increases downgradient and the redox zones in the reducing plume are characterized by: CH4, NH4+, Fe2+. Mn2+, HCO3- and NO3-. Lack of SO2-4 at that landfill eliminates the sulfide zone. Although it has not been observed at landfills, mineral alteration should result in precipitation of pyrite and/or siderite downgradient. Controls on the pH of leachate are the relative rates of production of HCO3-, NH4+ and CH4. Production of methane by fermentation at landfills results in 13C isotope fractionation and the accumulation of isotopically heavy ??CO2 (+10 to +18??? PDB). Isotope measurements may be useful to determine the extent of CO2 reduction in landfills and extent of dilution downgradient. The boundaries of reaction zones in stressed aquifers are determined by head distribution and flow velocity. Thus, if the groundwater flow is rapid relative to reaction rates, redox zones will develop downgradient. Where groundwater flow velocities are low the zones will overlap to the extent that they may be indeterminate. ?? 1979.

Field investigation of the quality of fresh and aged leachates from selected landfills receiving e-waste in an arid climate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiddee, Peeranart; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Mawson Lakes Campus, Adelaide 5095; Naidu, Ravi, E-mail: ravi.naidu@unisa.edu.au

Highlights: • E-waste comprises approximately 6% of the waste mass going to landfill in South Australia. • Significant amounts of metal(loids)s and PBDEs are released from e-waste mixed with municipal solid in landfill leachates. • Significantly elevated concentrations of lead and PBDEs are detected in groundwater wells downgradient of landfills. • Significant temporal variation exists in electrical conductivity and in the concentrations of As, Cd and Pb in leachates. - Abstract: The management of electronic waste (e-waste) is a serious problem worldwide and much of it is landfilled. A survey of four selected landfills in an arid region of Southmore » Australia was conducted to determine the proportion of e-waste in municipal waste and the properties of each landfill site. Leachate and groundwater samples were collected upgradient and downgradient of the landfills for analysis of polybrominated diphenyl ethers (PBDEs) and 14 metals and metalloids, including Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sb, V and Zn. Our data demonstrate that the selected landfills in South Australia continue to receive municipal waste containing in excess of 6%, or 25,000 tonnes per year, of e-waste. The leachates and groundwater collected from the landfills contained significantly elevated concentrations of Pb with the highest concentration in groundwater of 38 μg/l, almost four times higher than the Australian drinking water guideline of 10 μg/l. The presence of PBDEs was detected in both leachate and groundwater samples. Total PBDEs values of 2.13–59.75 ng/l in leachate samples were 10 times higher than in groundwater samples, which recorded a range of 0.41–6.53 ng/l at all sites. Moreover, the concentrations of metals and metalloids in sampled groundwater contained elevated levels of Al, As, Fe, Ni and Pb that exceeded Australian drinking water guideline values. For these reasons potential leaching of these contaminants is of concern and while difficult to attribute elevated contaminant levels to e-waste, we do not recommend continued disposal of e-waste in old landfills that were not originally designed to contain leachates. The survey also revealed temporal variation in the electrical conductivity and concentrations of As, Cd and Pb present in leachates of landfills in arid Mediterranean climates. These results are consistent with the marked variations in rainfall patterns observed for such climates. The solute concentration (EC and other ions including As, Cd and Pb) declines in the leachates during wet winter months (June to September), in contrast to tropical countries where such changes are observed during wet summer months.« less

Occurrence of Agricultural Chemicals in Shallow Ground Water and the Unsaturated Zone, Northeast Nebraska Glacial Till, 2002-04

USGS Publications Warehouse

Stanton, Jennifer S.; Steele, Gregory V.; Vogel, Jason R.

2007-01-01

Agricultural chemicals applied at the land surface in northeast Nebraska can move downward, past the crop root zone, to ground water. Because agricultural chemicals applied at the land surface are more likely to be observed in the shallowest part of an aquifer, an assessment of shallow ground-water and unsaturated zone quality in the northeast Nebraska glacial till was completed between 2002 and 2004. Ground-water samples were collected at the first occurrence of ground water or just below the water table at 32 sites located in areas likely affected by agriculture. Four of the 32 sites were situated along a ground-water flow path with its downgradient end next to Maple Creek. Twenty-eight sites were installed immediately adjacent to agricultural fields throughout the glacial-till area. In addition to those 32 sites, two sites were installed in pastures to represent ground-water conditions in a non-cropland setting. Ground-water samples were analyzed for physical properties and concentrations of nitrogen and phosphorus compounds, selected pesticides and pesticide degradates, dissolved solids, major ions, trace elements, and dissolved organic carbon. Chlorofluorocarbons (CFCs) or sulfur hexafluoride (SF6) concentrations were analyzed at about 70 percent of the monitoring wells to estimate the residence time of ground water. Borehole-core samples were collected from 28 of the well boreholes. Sediment in the unsaturated zone was analyzed for nitrate, chloride, and ammonia concentrations. Analytical results indicated that the agricultural chemicals most often detected during this study were nitrates and herbicides. Nitrate as nitrogen (nitrate-N) concentrations (2003 median 9.53 milligrams per liter) indicated that human activity has affected the water quality of recently recharged ground water in approximately two-thirds of the wells near corn and soybean fields. The principal pesticide compounds that were detected reflect the most-used pesticides in the area and included parent or degradate compounds of acetochlor, alachlor, atrazine, and metolachlor. Overall, pesticide concentrations in ground-water samples collected in 2003 and 2004 were small and did not exceed public drinking-water standards where established. On average, more pesticides were detected in the flow-path wells than in the glacial-till network wells. The presence of a perennial stream within 1,640 feet of a well was correlated to smaller nitrate-N concentrations in the well water, and the presence of a road ditch within 164 feet of the well was correlated to the presence of detectable pesticides in the well water. All other variables tested showed no significant correlations to nitrate-N concentrations or pesticide detections. Unsaturated zone soil cores collected in 2002 from well boreholes indicated that nitrogen in the forms of nitrate-N and ammonia as nitrogen (ammonia-N) was available in the unsaturated zone for transport to ground water. Concentrations of nitrate-N and ammonia-N in these soil cores were inversely correlated to depth, and nitrate-N concentrations were correlated to chloride concentrations.

Mercury concentrations of fish, river water, and sediment in the Río Ramis-Lake Titicaca watershed, Peru.

PubMed

Gammons, Christopher H; Slotton, Darell G; Gerbrandt, Butch; Weight, Willis; Young, Courtney A; McNearny, Richard L; Cámac, Eugenio; Calderón, Ruben; Tapia, Henri

2006-09-15

This study reports the first set of data on the concentration of mercury in muscle tissue of several varieties of fish from Lake Titicaca, including the pejerrey (Basilichthyes bonariensis), the carachi (Orestias), and 2 types of indigenous catfish (Trichomycterus). Approximately 27% of the pejerrey and 75% of the carachi exceeded the US EPA fish tissue-based water quality criterion level of 0.30 microg g(-1). Mercury levels of pejerrey increased with fish size, although this relationship was less apparent for the smaller carachi. The pejerrey and carachi are important food fish for local residents. A synoptic sampling of the Río Ramis--the largest tributary to Lake Titicaca--was conducted in an attempt to determine if mercury releases from artisanal gold mining could be an important source of Hg contamination to Lake Titicaca. Although highly elevated concentrations of Hg and other heavy metals were documented in headwater streams near the mining centers of La Rinconada and Cecilia, the quantity of Hg entering Lake Titicaca that could be attributed to mining in the Ramis watershed was below the quantifiable limit in our July 2002 study. This does not diminish the localized threat to mercury exposure for the artisanal gold miners themselves, as well as their families. Further studies of mercury dynamics in Lake Titicaca are recommended, as well as in the rivers draining into the lake. It is probable that most of the downgradient transport of Hg and other trace metals from the headwater mining centers occurs as suspended sediment during seasonal periods of high-flow.

An isotope hydrology study of the Kilauea volcano area, Hawaii

USGS Publications Warehouse

Scholl, M.A.; Ingebritsen, S.E.; Janik, C.J.; Kauahikaua, J.P.

1995-01-01

Isotope tracer methods were used to determine flow paths, recharge areas, and relative age for ground water in the Kilauea volcano area on the Island of Hawaii. Stable isotopes in rainfall show three distinct isotopic gradients with elevation, which are correlated with trade-wind, rain shadow, and high-elevation climatological patterns. Temporal variations in isotopic composition of precipitation are controlled more by the frequency of large storms than b.y seasonal temperature fluctuations. Consistency in results between two separate areas with rainfall caused by tradewinds and thermally-driven upslope airflow suggests that isotopic gradients with elevation may be similar on other islands in the tradewind belt, especially the other Hawaiian Islands, which have similar climatology and temperature lapse rates. Areal contrasts in ground-water stable isotopes and tritium indicate that the volcanic ri~ zones compartmentalize the regional ground-water system. Tritium levels in ground water within and downgradient of Kilauea's ri~ zones indicate relatively long residence times. Part of Kilauea's Southwest Ri~ Zone appears to act as a conduit for water from higher elevation, but there is no evidence for extensive down-ri~ flow in the lower East Ri~ Zone.

Pesticides in surface water, bed sediment, and ground water adjacent to commercial cranberry bogs, Lac du Flambeau Reservation, Vilas County, Wisconsin

USGS Publications Warehouse

Saad, David A.

2005-01-01

In samples from the Trout River, which is used as a source of water to maintain lake levels in the Corn Lakes, the only pesticides detected were the non-targeted compounds atrazine and deethyl atrazine, indicating it was not a source of targeted compounds detected in the Corn Lakes. Only two pesticides (chlorpyrifos and metolachlor) were detected in bed-sediment samples collected from the lakes; chlorpyrifos from Little Trout Lake and metolachlor from the Corn Lakes. Four pesticides (the targeted compounds napropamide and norflurazon and the non-targeted compounds atrazine and deethyl atrazine) were detected in ground-water samples from two of four sampled monitor wells. The highest ground-water concentrations (up to 0.14 ?g/L napropamide and 0.56 ?g/L norflurazon) were measured in samples from the monitoring well located directly downgradient from the Corn Lakes and commercial cranberry operations. No pesticides were detected in samples from the reference well located upgradient from the Corn Lakes and cranberry operations. Further study is needed to identify additional pesticides as well as chronic effects on aquatic organisms to determine whether cranberry-related pesticides affect the lake ecosystems of the Lac du Flambeau Reservation.

Impact of Wildfire on Solute Release in Forested Catchments, Jemez River, New Mexico, USA

NASA Astrophysics Data System (ADS)

Sanchez, R. A.; Meixner, T.; McIntosh, J. C.; Chorover, J.

2017-12-01

Wildfires represent a large disturbance to the hydrology and biogeochemistry of forested catchments. The number, size and severity of wildfires have significantly increased in the western United States since 1990. Nutrients and other elements (e.g. Ca) that were taken up and stored by biomass are released from burned vegetation during forest fires and transported downgradient via overland flow, shallow subsurface flow, and/or deep groundwater flow. Ash accumulations on hillslopes may also store particulate carbon and contain elevated concentrations of elements that maybe leached into surface and ground water over extended periods of time. In 2013, the Thompson Ridge wildfire burned headwater catchments in the Jemez River Basin Critical Zone Observatory (JRB-CZO) within the Valles Caldera National Preserve, New Mexico USA. The burn severity and area impacted were different in the three headwater catchments. This study investigated the impact of the wildfire on surface water quality, including how the fire-induced impacts evolved with time, and how biogeochemical processes controlled post-fire solute concentrations in the surface water. Comparison of pre- and post-fire surface water solute chemistry shows increases in major cations and anions following fire. Increases in nitrate and sulfate concentrations in streams after the wildfire were likely from leaching of burned biomass. The elevated NO3- and SO42- concentrations persisted for over two years, and were even higher during spring snowmelt. Meanwhile, base cation concentrations increased immediately, within a few weeks after the fire, likely related to leaching from combusted organic matter; and, over a period of approximately two months, base cation concentrations returned to pre-fire levels. Trace element behavior was also altered by fire. For example, while pre-fire aluminum concentrations in stream flow increased significantly during the wet seasons (snowmelt and monsoons), the post-fire observations do not show significant changes with increase in discharge.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.; Environmental Science Division

Contamination in groundwater at Canada, Kansas, was discovered in 1997, during limited private well sampling near former grain storage facilities of the Commodity Credit Corporation, U.S. Department of Agriculture (CCC/USDA). Subsequent investigations by the Kansas Department of Health and Environment (KDHE) confirmed carbon tetrachloride and nitrate concentrations in groundwater above the respective maximum contaminant levels (MCLs) of 5.0 {micro}g/L and 10.0 mg/L. The KDHE investigations identified both the former CCC/USDA grain storage facility and a private grain storage facility as likely sources for the carbon tetrachloride contamination. The CCC/USDA funded extension of a rural water district line to provide amore » permanent alternate water supply, and the KDHE has conducted long-term monitoring under the State Water Plan. This document presents an analysis of the available information for the Canada site, acquired in previous investigations and the long-term KDHE monitoring. This analysis forms the technical justification for a request to reclassify the former CCC/USDA grain storage facility at Canada as a site requiring no further action under the Intergovernmental Agreement (IGA) between the KDHE and the USDA's Farm Service Agency. The KDHE's long-term water level monitoring results indicate a consistent groundwater flow direction to the east-southeast. Consequently, the wells with the highest overall concentrations of carbon tetrachloride are downgradient from the private grain storage facility but not downgradient from the former CCC/USDA facility. The KDHE criterion for reclassification of a site is that contamination there should not pose an unacceptable risk, on the basis of analytical results for four consecutive, equally timed, sequenced sampling episodes over a period of no less than two years. In seven KDHE sampling events over a period of six years (2001-2007), the concentrations of carbon tetrachloride in the monitoring well on the former CCC/USDA property at Canada have ranged from 0.63 {micro}g/L to 2.9 {micro}g/L. These seven results are all below the MCL of 5.0 {micro}g/L, and they demonstrate that groundwater on the former CCC/USDA property has met the standard for carbon tetrachloride in drinking water since 2001 and does not pose a significant human health threat. Except for a two-year interval between sampling events in December 2003 and December 2005, the monitoring occurred at approximately annual intervals. The results warrant a request for reclassification of the Canada site to Resolved status on the KDHE's Identified Sites List, under Section III (Other Considerations) of KDHE policy BER-RS-024, Rev. 2001.« less

Vulnerability of ground water to contamination, northern Bexar County, Texas

USGS Publications Warehouse

Clark, Amy R.

2003-01-01

The Trinity aquifer, composed of Lower Cretaceous carbonate rocks, largely controls the ground-water hydrology in the study area of northern Bexar County, Texas. Discharge from the Trinity aquifer recharges the downgradient, hydraulically connected Edwards aquifer one of the most permeable and productive aquifers in the Nation and the sole source of water for more than a million people in south-central Texas. The unconfined, karstic outcrop of the Edwards aquifer makes it particularly vulnerable to contamination resulting from urbanization that is spreading rapidly northward across an "environmentally sensitive" recharge zone of the Edwards aquifer and its upgradient "catchment area," composed mostly of the less permeable Trinity aquifer.A better understanding of the Trinity aquifer is needed to evaluate water-management decisions affecting the quality of water in both the Trinity and Edwards aquifers. A study was made, therefore, in cooperation with the San Antonio Water System to assess northern Bexar County's vulnerability to ground-water contamination. The vulnerability of ground water to contamination in this area varies with the effects of five categories of natural features (hydrogeologic units, faults, caves and (or) sinkholes, slopes, and soils) that occur on the outcrop and in the shallow subcrop of the Glen Rose Limestone.Where faults affect the rates of recharge or discharge or the patterns of ground-water flow in the Glen Rose Limestone, they likewise affect the risk of water-quality degradation. Caves and sinkholes generally increase the vulnerability of ground water to contamination, especially where their occurrences are concentrated. The slope of land surface can affect the vulnerability of ground water by controlling where and how long a potential contaminant remains on the surface. Disregarding the exception of steep slopes which are assumed to have no soil cover the greater the slope, the less the risk of ground-water contamination. Because most soils in the study area are uniformly thin, they have only minimal effect on the vulnerability of ground water to contamination.The results of hydrogeologic mapping during the present study divide the outcrop of the Glen Rose Limestone into five mappable intervals, labeled (youngest to oldest) A through E. Of these intervals, only the middle (C) and the lowermost (E) generally provide appreciable permeability.The vulnerability assessment provided herein was determined by combining the presumed effects of selected natural features (with individual vulnerability ratings ranging from 0 through 35) using a grid-based, multilayer system of digital datasets and geographic information system analysis. The resulting vulnerability map comprises composite vulnerability ratings that range from 26 through 104. The relatively less vulnerable areas those containing no faults, sinkholes, or caves occupy about 92 percent of the study area. The most vulnerable areas are those containing both a fault and one or more caves. The distribution of the most vulnerable areas which trend from southwest to northeast, roughly parallel to the Balcones fault zone occur mainly where faults intersect caves.

Stable isotopes and volatile organic compounds along seven ground-water flow paths in divergent and convergent flow systems, southern California, 2000

USGS Publications Warehouse

Milby Dawson, Barbara J.; Belitz, Kenneth; Land, Michael; Danskin, Wesley R.

2003-01-01

Ground water is a major source of drinking water in southern California. In an effort to understand factors influencing the susceptibility of ground water tapped by public supply wells, the U.S. Geological Survey has undertaken studies in cooperation with the California State Water Resources Control Board. The vertical and lateral distribution of stable isotopes (deuterium and oxygen-18) and volatile organic compounds (VOC) were examined along seven ground-water flow paths in three urban ground-water basins in southern California: Central Basin in Los Angeles County, Main Basin in Orange County, and Bunker Hill Basin in San Bernardino County. Forty-seven monitoring wells and 100 public supply wells were sampled. The results of this study suggest that the direction of flow and perhaps the degree of confinement in an aquifer system are important controls on the distribution of VOCs. Ground-water flow in the Central and Main Basins in the southern California coastal plain is characterized as radially divergent, with ground-water flow directions moving outward from focused areas of recharge in the unconfined part of the aquifer system toward dispersed areas of discharge in the more confined part. In these basins, there is a volume of water containing VOCs that extends out into a volume of water containing no VOCs. This pattern suggests that radially divergent flow systems disperse VOCs in distal areas. The overall pattern also suggests that ground water in the pressure area is generally insulated from compounds introduced at land surface. These two factors?dispersion of VOCs due to divergence of flow and insulation from land-surface inputs?suggest that the susceptibility of public supply wells to surface contamination decreases with distance in radially divergent, well confined ground-water flow system. In the inland Bunker Hill Basin, ground-water flow is characterized as radially convergent; ground-water flow directions move inward from dispersed recharge areas in the unconfined part of the aquifer system, toward an area of focused discharge in the more confined part. The number of VOCs increased and the concentrations of individual VOCs increased, or remained the same, with increasing travel distance. Methyl tert-butyl ether was detected only in wells in the confined part of the aquifer system, suggesting that the confining units present in the distal part of the Bunker Hill Basin do not prevent VOCs from reaching ground water. These results suggest that VOCs in the Bunker Hill Basin are collected and concentrated as ground water moves downgradient because of radial convergenence of flow. They also suggest that ground water in the Bunker Hill Basin has an increasing opportunity to pick up VOCs introduced at land surface as it moves along a flow path. Some of the downgradient increase in VOC occurrence and concentration may be due to pumping that selectively removes cleaner ground water, thus leaving ground water containing more VOCs in the aquifer. These two factors?collection of VOCs due to convergence of flow and increasing opportunity to collect surficial contaminants perhaps due to a relative absence of confinement?suggest that the susceptibility of public supply wells to surface contamination increases with distance in radially convergent ground-water flow systems, particularly those that are unconfined.

Water resources and potential effects of surface coal mining in the area of the Woodson Preference Right Lease Application, Montana

USGS Publications Warehouse

Cannon, M.R.

1987-01-01

Federal coal lands of the Woodson Preference Right Lease Application are located in Dawson and Richland Counties, northeastern Montana. A probable mine area, comprised of the lease area and adjacent coal lands, contains about 220 million tons of recoverable lignite coal in the 12-37 ft thick Pust coal bed. A hydrologic study has been conducted in the area to describe the water resources and to evaluate potential effects of coal mining on the water resources. Geohydrologic data collected from wells and springs indicate that several aquifers exist in the area. Sandstone beds in the Tongue River Member of the Fort Union Formation (Paleocene age) are the most common aquifers and probably underlie the entire area. The Pust coal bed in the Tongue River Member is water saturated in part of the probable mine area and is dry in other parts of the probable mine area. Other aquifers, located mostly outside of the probable mine area, exist in gravel of the Flaxville Formation (Miocene of Pliocene age) and valley alluvium (Pleistocene and Holocene age). Chemical analyses of groundwater indicate a range in dissolved solids concentration of 240-2,280 mg/L. Surface water resources are limited. Most streams in the area are ephemeral and flow only in response to rainfall or snowmelt. Small reaches of the North and Middle Forks of Burns Creek have intermittent flow. Water sampled from a small perennial reach of the Middle Fork had a dissolved solids concentration of 700 mg/L. Mining of the Pust coal bed would destroy one spring and four stock wells, dewater areas of the Pust coal and sandstone aquifers, and probably lower water levels in seven stock and domestic wells. Mining in the valley of Middle Fork Burns Creek would intercept streamflow and alter flow characteristics of a small perennial reach of stream. Leaching of soluble minerals from mine spoils may cause a long-term degradation of the quality of water in the spoils and in aquifers downgradient from the spoils. Some of the effects on local water supplies could be mitigated by development of new wells in deeper sandstones of the Tongue River Member. Effects of mining on water resources would be minimized if only areas of dry coal were mined. (Author 's abstract)

Natural attenuation of chlorinated volatile organic compounds in ground water at Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington

USGS Publications Warehouse

Dinicola, Richard S.; Cox, S.E.; Landmeyer, J.E.; Bradley, P.M.

2002-01-01

The U.S. Geological Survey (USGS) evaluated the natural attenuation of chlorinated volatile organic compounds (CVOCs) in ground water beneath the former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center, Division Keyport, Washington. The predominant contaminants in ground water are trichloroethene (TCE) and its degradation byproducts cis-1,2-dichloroethene (cisDCE) and vinyl chloride (VC). The Navy planted two hybrid poplar plantations on the landfill in spring of 1999 to remove and control the migration of CVOCs in shallow ground water. Previous studies provided evidence that microbial degradation processes also reduce CVOC concentrations in ground water at OU 1, so monitored natural attenuation is a potential alternative remedy if phytoremediation is ineffective. This report describes the current (2000) understanding of natural attenuation of CVOCs in ground water at OU 1 and the impacts that phytoremediation activities to date have had on attenuation processes. The evaluation is based on ground-water and surface-water chemistry data and hydrogeologic data collected at the site by the USGS and Navy contractors between 1991 and 2000. Previously unpublished data collected by the USGS during 1996-2000 are presented. Natural attenuation of CVOCs in shallow ground water at OU 1 is substantial. For 1999-2000 conditions, approximately 70 percent of the mass of dissolved chlorinated ethenes that was available to migrate from the landfill was completely degraded in shallow ground water before it could migrate to the intermediate aquifer or discharge to surface water. Attenuation of CVOC concentrations appears also to be substantial in the intermediate aquifer, but biodegradation appears to be less significant; those conclusions are less certain because of the paucity of data downgradient of the landfill beneath the tide flats. Attenuation of CVOC concentrations is also substantial in surface water as it flows through the adjacent marsh and out to the tide flats. Attenuation processes other than dilution reduce the CVOC flux in marsh surface water by about 40 percent by the time the water discharges to the tide flats. Despite the importance of natural attenuation processes at reducing both the contaminant concentrations and the contaminant mass at OU 1, natural attenuation alone was not effective enough in the year 2000 to meet current numerical remediation goals for the site. That was in part due to the relatively short distance between the landfill and the adjacent marsh, and in part due to the extremely high CVOC concentrations directly beneath the landfill. Phytoremediation activities had some apparent effect on contaminant concentrations in ground water and surface water, but ground-water redox conditions to date (2000) were not affected by the February 1999 asphalt removal for tree planting. The poplar trees in the phytoremediation plantations were not yet mature in 2000, so the lack of discernible changes to date is understandable. Concentration changes of some redox-sensitive compounds suggest that increased recharge following asphalt removal diluted ambient landfill ground water. CVOC concentrations increased in some downgradient wells in both the northern and southern plantations after asphalt removal, whereas CVOC concentrations decreased in some upgradient wells in the southern plantation. A clear increase in CVOC concentrations in marsh surface water followed asphalt removal, apparently from increased contaminant discharge in ground water beneath the southern plantation. The results of the natural attenuation evaluation suggest than minor modifications to the current sampling plan may be beneficial to understanding the future impacts of phytoremediation and natural attenuation on the fate and distribution of CVOCs at OU 1.

Movement and fate of creosote waste in ground water, Pensacola, Florida; U.S. Geological Survey toxic waste--ground-water contamination program

USGS Publications Warehouse

Mattraw, H. C.; Franks, B.J.

1984-01-01

In 1983, the U.S. Geological Survey, Office of Hazardous Waste Hydrology, selected the former American Creosote Works site near Pensacola, Florida as a national research demonstration area. Seventy-nine years (1902-81) of seepage from unlined discharge impoundments had released creosote, diesel fuel, and pentachlorophenol (since 1950) wastes into the ground-water system. A cluster of from 2 to 5 wells constructed at different depths at 9 sites yielded water which revealed contamination 600 feet downgradient and to a depth of 100 feet below land surface near the site. The best cross-sectional representation of the contaminant plume was obtained from samples collected and analyzed for oxidation-reduction sensitive inorganic chemical constituents. Energy dispersive x-ray fluorescence detected recently formed iron carbonate in soil samples from highly reducing ground-water zones. Approximately eighty specific organic contaminants were isolated from ground-water samples by gas-chromotography/mass spectrometry. Column studies indicate the dimethyl phenols are not sorbed or degraded by the sand-and-gravel aquifer materials. Five of nineteen individual phenolic and related compounds are biodegradable based on anaerobic digestor experiments with ACW site bacterial populations. The potential impacts in the nearby Pensacola Bay biotic community are being evaluated. (USGS)

Hydrogeology, digital solute-transport simulation, and geochemistry of the Lower Cretaceous aquifer system near Baltimore, Maryland

USGS Publications Warehouse

Chapelle, Francis H.; with a section compiled by Kean, Tracey M.

1985-01-01

This study was made to develop information on the hydrogeology and ground-water geochemistry of the Patuxent and Patapsco aquifers (Lower Cretaceous) near Baltimore, Maryland. This information is needed to evaluate the availability and chemical quality of water from these aquifers.The Patuxent aquifer unconformably overlies Lower Paleozoic and Precambrian basement rocks and consists primarily of medium- to coarse-grained quartz sand. Discontinuous lenses of gravel and silty clay are commonly interbedded with the sand-sized material. The Patuxent aquifer in this area attains a thickness of 250 feet and transmissivities range from 2,000 to 8,000 feet squared per day. The Patuxent is the most productive source of ground water in the Baltimore area. In 1982, approximately 11 million gallons of water per day was produced from this unit. Several cones of depression, ranging from 30 to 50 feet below sea level, have developed in response to this pumping stress.The Arundel Formation conformably overlies the Patuxent aquifer. The Arundel is composed predominantly of clay and ranges from 0 to 150 feet thick. The Arundel exhibits very low vertical hydraulic conductivities that are on the order of 10-9 to 10-11 feet per second. This unit acts as the upper confining bed of the Patuxent aquifer in much of the project area. The Patapsco aquifer unconformably overlies the Arundel Formation and is a medium- to fine-grained quartz sand. The Patapsco functions as a water-table aquifer in much of the project area. Although the Patapsco has been heavily pumped in the past, pumpage from that aquifer in Baltimore was negligible in 1982.Brackish-water contamination of the Patuxent and Patapsco aquifers has been a major water-quality problem since the early 1900's. The Patuxent aquifer presently (1982) contains a circular plume of brackish-water contamination about 5 miles in diameter. This plume is centered on the Harbor district and has enlarged measurably since 1945. The Patapsco aquifer has a smaller zone of brackish-water contamination that has decreased in size since 1945. Borehole data demonstrate that the Arundel Formation has been breached by Pleistocene river channels near the Harbor district. These erosional channels provide a conduit for brackish water to intrude into the Patuxent aquifer. A two-dimensional areal solute-transport model of the Patuxent aquifer was constructed. This model was designed to estimate the future movement of the brackish-water plume based on alternative scenarios of aquifer use. Model simulations suggest that the plume will remain relatively immobile if 1982 pumping patterns continue into the foreseeable future. However, increased pumpage in the Marley Neck peninsula could draw the plume to the southeast and increase contamination of the Fairfield area.The water quality of the Patuxent aquifer is extremely variable. Because of this variability, it is useful to divide the aquifer into three water-quality zones: Zone 1 -- This zone corresponds to the plume of brackish-water contamination. Zone 2 -- This zone exhibits evidence of urbanization-related contamination such as measurable concentrations of organic chemicals and elevated concentrations of trace elements and total organic carbon. Zone 3 -- Water composition in this zone is controlled exclusively by naturally occurring chemical processes. These processes are dominated by reactions involving dissolved iron. Near the outcrop area, oxidation of pyrite and lignite consumes dissolved oxygen and produces ledges of iron hydroxide-cemented sandstones and conglomerates. The predominant dissolved iron species in oxic water is Fe(OH)2+. Downgradient, the water becomes anoxic and sulfate reduction becomes an important process. The predominant dissolved iron species in anoxic water is Fe2+.

Purgeable organic compounds at or near the Idaho Nuclear Technology and Engineering Center, Idaho National Laboratory, Idaho, 2015

USGS Publications Warehouse

Maimer, Neil V.; Bartholomay, Roy C.

2016-05-25

During 2015, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, collected groundwater samples from 31 wells at or near the Idaho Nuclear Technology and Engineering Center (INTEC) at the Idaho National Laboratory for purgeable organic compounds (POCs). The samples were collected and analyzed for the purpose of evaluating whether purge water from wells located inside an areal polygon established downgradient of the INTEC must be treated as a Resource Conservation and Recovery Act listed waste.POC concentrations in water samples from 29 of 31 wells completed in the eastern Snake River Plain aquifer were greater than their detection limit, determined from detection and quantitation calculation software, for at least one to four POCs. Of the 29 wells with concentrations greater than their detection limits, only 20 had concentrations greater than the laboratory reporting limit as calculated with detection and quantitation calculation software. None of the concentrations exceeded any maximum contaminant levels established for public drinking water supplies. Most commonly detected compounds were 1,1,1-trichoroethane, 1,1-dichloroethene, and trichloroethene.

Experimental salinity alleviation at Malaga Bend of the Pecos River, Eddy County, New Mexico

USGS Publications Warehouse

Havens, John S.; Wilkins, D.W.

1979-01-01

Upward-leaking brine, from a confined aquifer at the base of the Rustler Formation, mixes with fresher water in a shallow aquifer , resulting in discharge to the Pecos River in southern Eddy County, New Mexico, of about 0.5 cubic feet per second of saturated brine. Pumping brine from the aquifer at a rate greater than 0.5 cubic feet per second lowered the potentiometric head in the confined aquifer. From July 22, 1963, through December 1968, approximately 3,878 acre-feet of brine had been pumped into the Northeast Depression. The depression leaked brine to the Pecos River. Water downgradient of the depression increased in specific conductance ranging from 1,500 to 99,400 milligrams per liter chloride and water levels near the depression increased over 3 feet from 1963 to 1968. For water years 1952-63, the Pecos River gained about 240 tons per day of chloride in the reach from Malaga gaging station to Pierce Canyon Crossing. The average chloride gain to the Pecos River from July 1963 to August 1966 was 167 tons per day; the 1967-68 gain increased to 256 tons per day after a major flood in August 1966. (USGS)

Processes affecting geochemistry and contaminant movement in the middle Claiborne aquifer of the Mississippi embayment aquifer system

USGS Publications Warehouse

Katz, Brian G.; Kingsbury, James A.; Welch, Heather L.; Tollett, Roland W.

2012-01-01

Groundwater chemistry and tracer-based age data were used to assess contaminant movement and geochemical processes in the middle Claiborne aquifer (MCA) of the Mississippi embayment aquifer system. Water samples were collected from 30 drinking-water wells (mostly domestic and public supply) and analyzed for nutrients, major ions, pesticides, volatile organic compounds (VOCs), and transient age tracers (chlorofluorocarbons, tritium and helium-3, and sulfur hexafluoride). Redox conditions are highly variable throughout the MCA. However, mostly oxic groundwater with low dissolved solids is more vulnerable to nitrate contamination in the outcrop areas east of the Mississippi River in Mississippi and west Tennessee than in mostly anoxic groundwater in downgradient areas in western parts of the study area. Groundwater in the outcrop area was relatively young (apparent age of less than 40 years) with significantly (p 50 m depth) indicated contaminant movement from shallow parts of the aquifer into deeper oxic zones. Given the persistence of nitrate in young oxic groundwater that was recharged several decades ago, and the lack of a confining unit, the downward movement of young contaminated water may result in higher nitrate concentrations over time in deeper parts of the aquifer containing older oxic water.

Hydrology of Yucca Mountain and vicinity, Nevada-California : investigative results through mid-1983

USGS Publications Warehouse

Waddell, R.K.; Robison, J.H.; Blankennagel, R.K.

1984-01-01

Yucca Mountain, Nevada, is one of several sites under consideration for construction of the first repository for high-level nuclear waste. The climate is arid; few perennial streams are present in the region. Flash floods occasionally occur. The site is underlain by at least 1,800 meters of volcanic tuffs of Tertiary age; limestones and dolomites of Paleozoic age underlie much of the surrounding region, and, together with alluvial deposits, comprise the major aquifers. Yucca Mountain is in the Alkali Flat-Furnace Creek Ranch ground-water subbasin, which is part of the Death Valley ground-water basin. Discharge occurs at Alkali Flat almost entirely by evapotranspiration, and at Furnace Creek Ranch from small springs and seeps. Beneath Yucca Mountain, depth to water ranges from about 460 to 700 meters; the rock under consideration for construction of the repository is in the unsaturated zone. Rate of recharge at Yucca Mountain is small, perhaps much less than 5 millimeters per year. Within the saturated zone, water movement is principally along fractures. The hydraulic gradient is small east (downgradient) of Yucca Mountain, and increases to the north and west. Lack of effective-porosity data presently precludes accurate calculation of flow velocity and travel times. (USGS)

Hydrogeology and water quality of the Nutmeg Valley area, Wolcott and Waterbury, Connecticut

USGS Publications Warehouse

Mullaney, J.R.; Mondazzi, R.A.; Stone, J.R.

1999-01-01

Hydrogeologic investigations in an industrial area in Wolcott and Waterbury, Connecticut, have provided information on the geology, ground-water flow, and water quality of the area. Ground-water contamination by volatile organic compounds was discovered in the 1980?s in the Nutmeg Valley area, where approximately 43 industries and 25 residences use ground water for industrial and domestic supply. Unconsolidated surficial deposits, including glacial stratified deposits and till, are more than 85 feet thick and are interconnected with the underlying bedrock. The horizontal hydraulic conductivity of the stratified deposits ranges from 0.8 to 21 feet per day. Water in the surficial aquifer generally flows toward discharge points along Old Tannery Brook and the Mad River. Water in the bedrock aquifer flows through low-angle unroofing joints, high-angle fractures, and foliation-parallel fractures. Most high-angle water-bearing fractures strike north with an easterly dip. Most of the water pumped from bedrock wells in the study area comes from shallow fractures that are probably in hydraulic connection with the surficial aquifer. Short-circuit flow between fracture zones in wells is a likely pathway for contaminant transport. During periods of low streamflow, only a small amount of ground water discharges directly to Old Tannery Brook or to the Mad River. The amount of discharge is on the same order of magnitude as the estimated ground-water withdrawals. In northern parts of the valley bottom within the study area, downward vertical hydraulic gradients were present between wells in the surficial and bedrock aquifers. In southern parts of the valley, however, vertical gradients were upward from the bedrock to the surficial aquifer. Vertical gradients can change seasonally in response to different amounts of ground-water recharge and to stresses caused by ground-water withdrawals, which can in turn facilitate the spread of contamination. Vapor-diffusion samplers were installed in streambeds to identify zones where water containing volatile organic compounds was discharging to streams in the study area. Three areas with high vapor concentrations of trichloroethene and tetrachloroethene were identified. Concentrations of trichloroethene as high as 30,000 parts per billion by volume were detected. Three of 44 wells sampled contained concentrations of volatile organic compounds, including trichloroethene and tetrachloroethene, above primary drinking water standards. Based on the findings of this and previous investigations, water in the bedrock aquifer in the southern part of the study area is likely to contain trichloroethene, tetrachloroethene, and 1,1,1-trichloroethane. Volatile organic compounds also were detected in stream samples from the downstream end of Old Tannery Brook and the Mad River. Concentrations of major ions and trace elements (with one exception) did not exceed primary drinking water standards in any ground-water or surface-water samples collected. Ground-water samples collected downgradient from the Waterbury North End Disposal Area contained ethyl ether, chlorobenzene, and elevated concentrations of dissolved solids, similar to samples of landfill leachate and groundwater samples collected from springs and wells adjacent to the landfill.

Evaluation of Elevated Tritium Levels in Groundwater Downgradient from the 618-11 Burial Ground Phase I Investigations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dresel, P.E.; Smith, R.M.; Williams, B.A.

2000-05-01

This report describes the results of the preliminary investigation of elevated tritium in groundwater discovered near the 618-11 burial ground, located in the eastern part of the Hanford Site. Tritium in one well downgradient of the burial ground was detected at levels up to 8,140,000 pCi/L. The 618-11 burial ground received a variety of radioactive waste from the 300 Area between 1962 and 1967. The burial ground covers 3.5 hectare (8.6 acre) and contains trenches, large diameter caissons, and vertical pipe storage units. The burial ground was stabilized with a native sediment covering. The Energy Northwest reactor complex was constructedmore » immediately east of the burial ground.« less

Preliminary evaluation of ground-water contamination by coal-tar derivatives, St. Louis Park area, Minnesota

USGS Publications Warehouse

Hult, Marc F.; Schoenberg, Michael E.

1984-01-01

Drift materials on and south of the site have been contaminated by surface spills and by infiltration of contaminated process water. Near the contamination source, a hydrocarbon fluid phase is moving vertically downward relative to movement of the aqueous phase. Fluid pumped from an observation well in this area contained 6,000 milligrams per liter total organic carbon. Dissolved coal-tar constituents in the drift and the uppermost bedrock unit over most of the area, the Platteville aquifer, have moved at least 4,000 feet downgradient to a drift-filled bedrock valley. At the valley, it seems that the Platteville aquifer and the Glenwood confining bed have been removed by erosion and that contaminants with a concentration of approximately 2 milligrams per liter dissolved organic carbon are entering the underlying St. Peter aquifer. Chemical analyses of fluid pumped from observation wells suggest that soluble, low-molecular-weight compounds are moving preferentially through the drift and the Platteville aquifer.

Effect of Hydrologic and Geochemical Conditions on Oxygen-Enhanced Bioremediation in a Gasoline-Contaminated Aquifer

USGS Publications Warehouse

Landmeyer, J.E.; Bradley, P.M.

2003-01-01

The effect of pre-existing factors, e.g., hydrologic, geochemical, and microbiological properties, on the results of oxygen addition to a reformulated gasoline-contaminated groundwater system was studied. Oxygen addition with an oxygen-release compound (a proprietary form of magnesium peroxide produced different results with respect to dissolved oxygen (DO) generation and contaminant decrease in the two locations. Oxygen-release compound injected at the former UST source area did not significantly change measured concentrations of DO, benzene, toluene, or MTBE. Conversely, oxygen-release compound injected 200 m downgradient of the former UST source area rapidly increased DO levels, and benzene, toluene, and MTBE concentrations decreased substantially. The different results could be related to differences in hydrologic and geochemical conditions that characterized the two locations prior to oxygen addition. The lack of recharge to ground water in the paved UST source area led to a much larger geochemical sink for DO compared to ground water in the unpaved area.

Fate of herbicides in a shallow aerobic aquifer: A continuous field injection experiment (Vejen, Denmark)

NASA Astrophysics Data System (ADS)

Broholm, Mette M.; Rügge, Kirsten; Tuxen, Nina; HøJberg, Anker L.; MosbæK, Hans; Bjerg, Poul L.

2001-12-01

A continuous, natural gradient, field injection experiment, involving six herbicides and a tracer, was performed in a shallow aerobic aquifer near Vejen, Denmark. Bentazone, (±)-2-(4-chloro-2-methylphenoxy) propanoic acid (MCPP), dichlorprop, isoproturon, and the dichlobenil metabolite 2,6-dichlor-benzamide (BAM) were injected along with 2-methyl-4,6-dinitrophenol (not discussed in this paper) and the tracer bromide. The injection lasted for 216 days and created a continuous plume in the aquifer. The plume was monitored in three dimensions in 96 multilevel samplers of 6-9 points each for 230 days, with selected individual points for a longer period. The bromide plume followed a complex path through the monitoring network downgradient of the injection wells. The plume movement was controlled by spatially varied hydraulic conductivities of the sand deposit and influenced by asynchronous seasonal variation in groundwater potentials. An average flow velocity of 0.5 m/d was observed, as depicted by bromide. Bentazone, BAM, MCPP, and dichlorprop retardation was negligible, and only slight retardation of isoproturon was observed in the continuous injection experiment and a preceding pulse experiment. No degradation of bentazone was observed in the aerobic aquifer during the monitoring period. BAM and isoproturon were not degraded within 5 m downgradient of the injection. The two phenoxy acids MCPP and dichlorprop were both degraded in the aerobic aquifer. Near the source a lag phase was observed followed by fast degradation of the phenoxy acids, indicating growth kinetics. The phenoxy acids were completely degraded within l m downgradient of the injection wells, resulting in the plumes being divided into small plumes at the injection wells and pulses farther downgradient. During the lag phase, phenoxy acids had spread beyond the 25 m long monitoring network. However, the mass of the phenoxy acids passing the 10-25 m fences never matched the corresponding bentazone or bromide masses, and the pulse was observed to shrink in size. This indicates that this pulse of phenoxy acids was being partially degraded at a low rate as it traveled through the aquifer.

Estimates of residence time and related variations in quality of ground water beneath Submarine Base Bangor and vicinity, Kitsap County, Washington

USGS Publications Warehouse

Cox, S.E.

2003-01-01

Estimates of residence time of ground water beneath Submarine Base Bangor and vicinity ranged from less than 50 to 4,550 years before present, based on analysis of the environmental tracers tritium, chlorofluorocarbons (CFCs), and carbon-14 (14C), in 33 ground-water samples collected from wells tapping the ground-water system. The concentrations of multiple environmental tracers tritium, CFCs, and 14C were used to classify ground water as modern (recharged after 1953), pre-modern (recharged prior to 1953), or indeterminate. Estimates of the residence time of pre-modern ground water were based on evaluation of 14C of dissolved inorganic carbon present in ground water using geochemical mass-transfer modeling to account for the interactions of the carbon in ground water with carbon of the aquifer sediments. Ground-water samples were obtained from two extensive aquifers and from permeable interbeds within the thick confining unit separating the sampled aquifers. Estimates of ground-water residence time for all ground-water samples from the shallow aquifer were less than 45 years and were classified as modern. Estimates of the residence time of ground water in the permeable interbeds within the confining unit ranged from modern to 4,200 years and varied spatially. Near the recharge area, residence times in the permeable interbeds typically were less than 800 years, whereas near the discharge area residence times were in excess of several thousand years. In the deeper aquifers, estimates of ground-water residence times typically were several thousand years but ranged from modern to 4,550 years. These estimates of ground-water residence time based on 14C were often larger than estimates of ground-water residence time developed by particle-tracking analysis using a ground-water flow model. There were large uncertainties?on the order of 1,000-2,000 years?in the estimates based on 14C. Modern ground-water tracers found in some samples from large-capacity production wells screened in the deeper aquifer may be the result of preferential ground-water pathways or induced downward flow caused by pumping stress. Spatial variations in water quality were used to develop a conceptual model of chemical evolution of ground water. Stable isotope ratios of deuterium and oxygen-18 in the 33 ground-water samples were similar, indicating similar climatic conditions and source of precipitation recharge for all of the sampled ground water. Oxidation of organic matter and mineral dissolution increased the concentrations of dissolved inorganic carbon and common ions in downgradient ground waters. However, the largest concentrations were not found near areas of ground-water discharge, but at intermediate locations where organic carbon concentrations were greatest. Dissolved methane, derived from microbial methanogenesis, was present in some ground waters. Methanogenesis resulted in substantial alteration of the carbon isotopic composition of ground water. The NETPATH geochemical model code was used to model mass-transfers of carbon affecting the 14C estimate of ground-water residence time. Carbon sources in ground water include dispersed particulate organic matter present in the confining unit separating the two aquifers and methane present in some ground water. Carbonate minerals were not observed in the lithologic material of the ground-water system but may be present, because they have been found in the bedrock of stream drainages that contribute sediment to the study area.

Modeling chloride movement in the alluvial aquifer at the Rocky Mountain Arsenal, Colorado

USGS Publications Warehouse

Konikow, Leonard F.

1977-01-01

A solute-transport model that can be used to predict the movement of dissolved chemicals in flowing ground water was applied to a problem of ground-water contamination at the Rocky Mountain Arsenal, near Denver, Colo. The model couples a finite-difference solution to the ground-water flow equation with the method-of-characteristics solution to the solute-transport equation. From 1943 to 1956 liquid industrial wastes containing high chloride concentrations were disposed into unlined ponds at the Arsenal. Wastes seeped out of the unlined disposal ponds and spread for many square miles in the underlying shallow alluvial aquifer. Since 1956 disposal has been into an asphalt-lined reservoir, which contributed to a decline in ground-water contamination by 1972. The simulation model quantitatively integrated the effects of the major factors that controlled changes in chloride concentrations and accurately reproduced the 30-year history of chloride ground-water contamination. Analysis of the simulation results indicates that the geologic framework of the area markedly restricted the transport and dispersion of dissolved chemicals in the alluvium. Dilution, from irrigation recharge and seepage from unlined canals, was an important factor in reducing the level of chloride concentrations downgradient from the Arsenal. Similarly, recharge of uncontaminated water from the unlined ponds since 1956 has helped to dilute and flush the contaminated ground water.

Methanogenic biodegradation of creosote contaminants in natural and simulated ground-water ecosystems

USGS Publications Warehouse

Godsy, E. Michael; Goerlitz, Donald; Grbic-Galic, Dunja

1992-01-01

Wastes from a wood preserving plant in Pensacola, Florida have contaminated the near-surface sand-and-gravel aquifer with creosote-derived compounds and pentachlorophenol. Contamination resulted from the discharge of plant waste waters to and subsequent seepage from unlined surface impoundments that were in direct hydraulic contact with the ground water. Two distinct phases resulted when the creosote and water mixed: a denser than water hydrocarbon phase that moved vertically downward, and an organic-rich aqueous phase that moved laterally with the ground-water flow. The aqueous phase is enriched in organic acids, phenolic compounds, single- and double-ring nitrogen, sulfur, and oxygen containing compounds, and single- and double-ring aromatic hydrocarbons. The ground water is devoid of dissolved O2, is 60-70% saturated with CH4 and contains H2S. Field analyses document a greater decrease in concentration of organic fatty acids, benzoic acid, phenol, 2-, 3-, 4-methylphenol, quinoline, isoquinoline, 1(2H)-quinolinone, and 2(1H)-isoquinolinone during downgradient movement in the aquifer than could be explained by dilution and/or dispersion. Laboratory microcosm studies have shown that within the study region, this effect can be attributed to microbial degradation to CH4 and CO2. A small but active methanogenic population was found on sediment materials taken from highly contaminated parts of the aquifer.

Calcium carbonate-based permeable reactive barriers for iron and manganese groundwater remediation at landfills.

PubMed

Wang, Yu; Pleasant, Saraya; Jain, Pradeep; Powell, Jon; Townsend, Timothy

2016-07-01

High concentrations of iron (Fe(II)) and manganese (Mn(II)) reductively dissolved from soil minerals have been detected in groundwater monitoring wells near many municipal solid waste landfills. Two in situ permeable reactive barriers (PRBs), comprised of limestone and crushed concrete, were installed downgradient of a closed, unlined landfill in Florida, USA, to remediate groundwater containing high concentrations of these metals. Influent groundwater to the PRBs contained mean Fe and Mn concentrations of approximately 30mg/L and 1.62mg/L, respectively. PRBs were constructed in the shallow aquifer (maximum depth 4.6m below land surface) and groundwater was sampled from a network of nearby monitoring wells to evaluate barrier performance in removing these metals. PRBs significantly (p<0.05) removed dissolved Fe and Mn from influent groundwater; Fe was removed from influent water at average rates of 91% and 95% (by mass) for the limestone and crushed concrete PRBs, respectively, during the first year of the study. The performance of the PRBs declined after 3years of operation, with Fe removal efficiency decreasing to 64% and 61% for limestone and concrete PRBs, respectively. A comparison of water quality in shallow and deep monitoring wells showed a more dramatic performance reduction in the deeper section of the concrete PRB, which was attributed to an influx of sediment into the barrier and settling of particulates from the upper portions of the PRBs. Although removal of Fe and Mn from redox impacts was achieved with the PRBs, the short time frame of effectiveness relative to the duration of a full-scale remediation effort may limit the applicability of these systems at some landfills because of the construction costs required. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mapping bedrock surface contours using the horizontal-to-vertical spectral ratio (HVSR) method near the middle quarter srea, Woodbury, Connecticut

USGS Publications Warehouse

Brown, Craig J.; Voytek, Emily B.; Lane, John W.; Stone, Janet R.

2013-01-01

The bedrock surface contours in Woodbury, Connecticut, were determined downgradient of a commercial zone known as the Middle Quarter area (MQA) using the novel, noninvasive horizontal-to-vertical (H/V) spectral ratio (HVSR) passive seismic geophysical method. Boreholes and monitoring wells had been drilled in this area to characterize the shallow subsurface to within 20 feet (ft) of the land surface, but little was known about the deep subsurface, including sediment thicknesses and depths to bedrock (Starn and Brown, 2007; Brown and others, 2009). Improved information on the altitude of the bedrock surface and its spatial variation was needed for assessment and remediation of chlorinated solvents that have contaminated the overlying glacial aquifer that supplies water to wells in the area.

Fate and transport of petroleum hydrocarbons in the subsurface near Cass Lake, Minnesota

USGS Publications Warehouse

Drennan, Dina M.; Bekins, Barbara A.; Warren, Ean; Cozzarelli, Isabelle M.; Baedecker, Mary Jo; Herkelrath, William N.; Delin, Geoffrey N.; Rosenbauer, Robert J.; Campbell, Pamela L.

2010-01-01

The U.S. Geological Survey (USGS) investigated the natural attenuation of subsurface petroleum hydrocarbons leaked over an unknown number of years from an oil pipeline under the Enbridge Energy Limited Partnership South Cass Lake Pumping Station, in Cass Lake, Minnesota. Three weeks of field work conducted between May 2007 and July 2008 delineated a dissolved plume of aromatic hydrocarbons and characterized the biodegradation processes of the petroleum. Field activities included installing monitoring wells, collecting sediment cores, sampling water from wells, and measuring water-table elevations. Geochemical measurements included concentrations of constituents in both spilled and pipeline oil, dissolved alkylbenzenes and redox constituents, sediment bioavailable iron, and aquifer microbial populations. Groundwater in this area flows east-southeast at approximately 26 meters per year. Results from the oil analyses indicate a high degree of biodegradation, characterized by nearly complete absence of n-alkanes. Cass Lake oil samples were more degraded than two oil samples collected in 2008 from the similarly contaminated USGS Bemidji, Minnesota, research site 40 kilometers away. Based on 19 ratios developed for comparing oil sources, the conclusion is that the oils at the two sites appear to be from the same hydrocarbon source. In the Cass Lake groundwater plume, benzene concentrations decrease by three orders of magnitude within 150 meters (m) downgradient from the oil body floating on the water table (between well MW-10 and USGS-4 well nest). The depths of the highest benzene concentrations increase with distance downgradient from the oil, a condition typical of plumes in shallow, unconfined aquifers. Background groundwater, which is nearly saturated with oxygen, becomes almost entirely anaerobic in the plume. As at the Bemidji site, the most important biodegradation processes are anaerobic and dominated by iron reduction. The similarity between the Cass Lake and Bemidji benzene degradation rates, redox conditions, and aquifer material all support a hypothesis that the Cass Lake plume, like the Bemidji plume, is decades old. As concentrations of alkylbenzenes in the oil decrease over time, the benzene concentrations in the groundwater plume will also decrease and the plume is expected to shrink. The Fox Creek wetland, about 250 m south of the Cass Lake site, is the nearest receptor to the south.

Distribution and Migration of Ordnance-Related Compounds and Oxygen and Hydrogen Stable Isotopes in Ground Water near Snake Pond, Sandwich, Massachusetts

USGS Publications Warehouse

LeBlanc, Denis R.; Massey, Andrew J.; Cochrane, Jessica J.; King, Jonathan H.; Smith, Kirk P.

2008-01-01

Explosive compounds, such as RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), and the propellant compound perchlorate are present in ground water near Snake Pond, a ground-water flow-through glacial kettle pond in the glacial sand and gravel aquifer on western Cape Cod near Camp Edwards on the Massachusetts Military Reservation. The contaminants originate from the J-3 Range ordnance training and testing area. Ground-water samples were collected at 10 sites near the pond to determine the paths of the contaminants as they underflow or completely or partially discharge into the pond. Water-quality profiles were developed for sites on opposite ends of a 200-foot-long intermittent island near the northern, upgradient end of the pond by collecting water samples from two temporary drive-point borings. RDX was detected at both locations between 60 and 90 feet below the pond level. The highest RDX concentration was 0.99 micrograms per liter. Perchlorate was detected at only one location on the island, between 95 and 100 feet below the pond level at a concentration of 0.61 micrograms per liter. Profiles of oxygen and hydrogen stable isotopes were developed for seven sites spaced 300 to 600 feet apart along the southern, downgradient shore of the pond. A transition from heavier to lighter oxygen and hydrogen isotopes was observed at an altitude of about -50 feet. This transition most likely is the boundary between evaporation-affected pond water that is seeping into the aquifer and ground water that has passed beneath the pond. RDX was not detected in the ground-water samples collected south of the pond. Perchlorate was detected only in one sample from a shallow depth in one boring. The results of these analyses indicate that the J-3 Range plume contains low concentrations of RDX and perchlorate (less than 1 microgram per liter) as it passes beneath the northern end of Snake Pond. Results of ground-water-flow modeling indicate that ground water containing these low levels of RDX and perchlorate discharges into the pond south of the island. If the contaminated ground water should travel as far as the southern shore of the pond, it would be overlain near the shore by a zone of pond water seeping into the aquifer that is about 100 feet thick.

Effects of a reactive barrier and aquifer geology on metal distribution and mobility in a mine drainage impacted aquifer.

PubMed

Doerr, Nora A; Ptacek, Carol J; Blowes, David W

2005-06-01

The Nickel Rim aquifer has been impacted for five decades by a metal-rich plume generated from the Nickel Rim mine tailings impoundment. Metals released by the oxidation of pyrrhotite in the unsaturated zone of the tailings migrate into the downgradient aquifer, affecting both the groundwater and the aquifer solids. A reactive barrier has been installed in the aquifer to remove sulfate and metals from the groundwater. The effect of the reactive barrier on metal concentrations in the aquifer solids has not previously been studied. In this study, a series of selective extraction procedures was applied to cores of aquifer sediment, to ascertain the distribution of metals among various solid phases present in the aquifer. Extraction results were combined with groundwater chemistry, geochemical modelling and solid-phase microanalyses, to assess the potential mobility of metals under changing geochemical conditions. Reactions within the reactive barrier caused an increase in the solid-phase carbonate content downgradient from the barrier. The concentrations of poorly crystalline, oxidized phases of Mn and Fe, as well as concentrations of Cr(III) associated with oxidized Fe, and poorly crystalline Zn, are lower downgradient from the barrier, whereas total solid-phase metal concentrations remain constant. Iron and Mn accumulate as oxidized, easily extractable forms in a peat layer overlying the aquifer. Although these oxides may buffer reducing plumes, they also have the potential to release metals to the groundwater, should a reduced condition be imposed on the aquifer by remedial actions.

Crude oil in a shallow sand and gravel aquifer-II. Organic geochemistry

USGS Publications Warehouse

Eganhouse, R.P.; Baedecker, M.J.; Cozzarelli, I.M.; Aiken, G.R.; Thorn, K.A.; Dorsey, T.F.

1993-01-01

Crude oil spilled from a pipeline break in a remote area of north-central Minnesota has contaminated a shallow glacial outwash aquifer. Part of the oil was sprayed over a large area to the west of the pipeline and part of it accumulated in an oil body that floats at the water table to the east of the point of discharge. Total dissolved organic carbon (TDOC) concentrations in shallow groundwater collected in the oil spray area reach 16 mg/l. This is nearly an order of magnitude higher than the TDOC concentrations of native groundwater (???2-3 mg/l). The additional TDOC derives from the partial degradation of petroleum residues deposited at the land surface and transported to the aquifer by vertical recharge. In the vicinity of the oil body, TDOC concentrations in groundwater are 48 mg/l, 58% of the TDOC being composed of non-volatile organic C. The majority of the volatile DOC (63%) is a mixture of low-molecular-weight saturated, aromatic and alicyclic hydrocarbons derived from the oil. Downgradient from the oil body along the direction of groundwater flow, concentrations of all measured constituents of the TDOC pool decrease. Concentrations begin to decline most rapidly, however, in the zone where dissolved O2 concentrations begin to increase, ???50 m downgradient from the leading edge of the oil. Within the anoxic zone near the oil body, removal rates of isometric monoaromatic hydrocarbons vary widely. This indicates that the removal processes are mediated mainly by microbiological activity. Molecular and spectroscopic characterization of the TDOC and its spatial and temporal variation provide evidence of the importance of biogeochemical processes in attenuating petroleum contaminants in this perturbed subsurface environment. ?? 1993.

Use of plume mapping data to estimate chlorinated solvent mass loss

USGS Publications Warehouse

Barbaro, J.R.; Neupane, P.P.

2006-01-01

Results from a plume mapping study from November 2000 through February 2001 in the sand-and-gravel surficial aquifer at Dover Air Force Base, Delaware, were used to assess the occurrence and extent of chlorinated solvent mass loss by calculating mass fluxes across two transverse cross sections and by observing changes in concentration ratios and mole fractions along a longitudinal cross section through the core of the plume. The plume mapping investigation was conducted to determine the spatial distribution of chlorinated solvents migrating from former waste disposal sites. Vertical contaminant concentration profiles were obtained with a direct-push drill rig and multilevel piezometers. These samples were supplemented with additional ground water samples collected with a minipiezometer from the bed of a perennial stream downgradient of the source areas. Results from the field program show that the plume, consisting mainly of tetrachloroethylene (PCE), trichloroethene (TCE), and cis-1,2-dichloroethene (cis-1,2-DCE), was approximately 670 m in length and 120 m in width, extended across much of the 9- to 18-m thickness of the surficial aquifer, and discharged to the stream in some areas. The analyses of the plume mapping data show that losses of the parent compounds, PCE and TCE, were negligible downgradient of the source. In contrast, losses of cis-1,2-DCE, a daughter compound, were observed in this plume. These losses very likely resulted from biodegradation, but the specific reaction mechanism could not be identified. This study demonstrates that plume mapping data can be used to estimate the occurrence and extent of chlorinated solvent mass loss from biodegradation and assess the effectiveness of natural attenuation as a remedial measure.

Borehole Data Package for 1998 Wells Installed at Single-Shell Tank Waste Management Area TX-TY

DOE Office of Scientific and Technical Information (OSTI.GOV)

DG Horton; FN Hodges

1999-03-23

Four new Resource Conservation and Recovery Act (RCRA) groundwater monitoring wells were installed at the single-shell tank farm Waste Management Area (WMA) TX-TY during August through November of 1998 in fi,dfillment of Tri-Party Agreement (Eoology 1996) milestone M-24-38. The wells are 299-W1O-26, 299-W14-13, 299-W14-14, and 299-W15-40. Well 299-W1O-26 is located outside the east fence of the TY tank farm and replaces downgradient well299-W1O-18; well 299-W14-13 is located along the east fence near the northeast corner of the TX tank f- and replaces downgradient well 299-W14-12; well 299-W14-14 is located outside the east fence in the south ha.lfof the TX tankmore » fiirm and is anew downgradient well; and well 299-W15-40 is located on the west side of the TX tank farm and is anew upgradient well. The locations of all wells in the monitoring network are shown on Figure 1. The groundwater monitoring plan for WMA TX-TY (Caggiano and Goodwin 1991) describes the hydrogeology of the 200 West Area and WMA TX-TY. An Interim Change Notice to the groundwater monitoring plan provides justification for the new wells. The new wells were constructed to the speciii- cations and requirements described in Washington Administrative Code (WAC) 173-160 and WAC 173-303. This document compiles &fiormation on the drilling and construction, well development pump instal- latio~ groundwater sampling, and sediment testing applicable to wells 299-W1O-26, 299-W14-13, 299-W14-14, and 299-W15-40. Appendix A contains the geologist's log, the Well Construction Sum- mary Repo~ and Well Summary Sheet (as-built diagram); Appendix B contains results of laboratory analyses of particle size distribution, p~ conductivity, calcium carbonate conten~ major cation and anion concentrations from 1:1 water: sediment extracts, and moisture conten~ Appendix C contains geophysical logs; and Appendix D contains the analytical results from groundwater samples obtained during well construction. Aqutier tests (slug tests) were performed on all the new wells after well completions. Results of the aquifer tests will be reported elsewhere. Additiond documentation concerning well construction is on fde with Bechtel Hanfor& Inc., Richland, Washington.« less

Synoptic survey of septic indicators in streams and springs at Monte Sano Mountain, Madison County, Alabama, January 29-31, 1998

USGS Publications Warehouse

McPherson, Ann K.; Mooty, Will S.

1999-01-01

The U.S. Geological Survey conducted a synoptic investigation of fecal bacterial pollution in headwater streams and springs on Monte Sano Mountain. A total of 18 sites were sampled over a 3 day period in late January 1998. Fifteen of the sites were located hydrologically downgradient from residential areas on top of Monte Sano Mountain. Three additional sites were selected as background sites in unpopulated areas on Huntsville Mountain, south of Monte Sano Mountain. Sampling was conducted during a period of high baseflow after a recent storm when no surface runoff was present. Any contaminants identified in the streams and springs were likely derived from ground-water discharge because overland flow was not evident. Four of the five sites in the Pottsville-Pennington unit (uppermost) with the highest concentration of residential land use had Escherichia coli (E. coli) concentrations that were more than 25 times the background level. In contrast, with the exception of one site, E. coli concentrations in the Bangor-Monteagle unit (middle) and Tuscumbia unit (lowermost) were at or near background levels. Caffeine was also detected in the Pottsville-Pennington unit at a site with one of the highest densities of E. coli. Elevated levels of nitrate and chloride were also identified at sites in the Pottsville-Pennington unit. The results of this synoptic sampling event identified elevated concentrations of fecal bacteria in the Pottsville-Pennington unit at the top of the mountain. These elevated bacterial concentrations occurred in conjunction with caffeine detection and elevated levels of nitrate and chloride. This indicates that there is a potential water-quality problem related to discharge from the shallow ground-water system. These sites are located in close proximity to residential development, indicating that the most probable source of the elevated fecal bacterial concentrations was septic tank effluent.

Ground-Water Age and Quality in the High Plains Aquifer near Seward, Nebraska, 2003-04

USGS Publications Warehouse

Stanton, Jennifer S.; Landon, Matthew K.; Turco, Michael J.

2007-01-01

The U.S. Geological Survey, in cooperation with the City of Seward, Nebraska, conducted a study of ground-water age and quality to improve understanding of: (1) traveltimes from recharge areas to public-supply wells, (2) the effects of geochemical reactions in the aquifer on water quality, and (3) how water quality has changed historically in response to land-use practices. Samples were collected from four supply wells in the Seward west well field and from nine monitoring wells along two approximate ground-water flow paths leading to the well field. Concentrations of three different chlorofluorocarbons (CFC-12, CFC-11, and CFC-113), sulfur hexafluoride (SF6), and ratios of tritium (3H) to helium-3 (3He) isotope derived from radioactive decay of 3H were used to determine the apparent recharge age of ground-water samples. Age interpretations were based primarily on 3H/3He and CFC-12 data. Estimates of apparent ground-water age from tracer data were complicated by mixing of water of different ages in 10 of the 13 ground-water samples collected. Apparent recharge dates of unmixed ground-water samples or mean recharge dates of young fractions of mixed water in samples collected from monitoring wells ranged from 1985 to 2002. For monitoring-well samples containing mixed water, the fraction of the sample composed of young water ranged from 26 to 77 percent of the sample. Apparent mean recharge dates of young fractions in samples collected from four supply wells in the Seward west well field ranged from about 1980 to 1990. Estimated fractions of the samples composed of young water ranged from 39 to 54 percent. It is implicit in the mixing calculations that the remainder of the sample that is not young water is composed of water that is more than 60 years old and contains no detectable quantities of modern atmospheric tracers. Estimated fractions of the mixed samples composed of 'old' water ranged from 23 to 74 percent. Although alternative mixing models can be used to interpret the results, the mean age and mixing fractions from the primary mixing models used were fairly similar. Relations of ground-water age and nitrate concentrations to depth were not consistent across the study area. In some well nests, more young water and nitrate were present near the bottom than in the middle of the aquifer. These results probably reflect pumping from irrigation and supply wells, which are screened primarily in the lower part of the aquifer, and draw younger water downward in the aquifer. Substantial mixing probably occurs because the aquifer is relatively thin (50 feet) and has a relatively high density of wells (about five pumping wells per square mile). The most reliable estimate of horizontal traveltimes based on differences in ground-water ages between a shallow monitoring well at the upgradient end of the northwest well transect and the deep well at the downgradient end of the well transect was 9 years to travel a distance of about 2 miles. The general similarity of ages at similar depths between different well nests is consistent with the fact that horizontal flow in the aquifer is relatively rapid. Concentrations of nitrate (as nitrogen) in untreated ground-water samples from supply wells in the well field were larger than the U.S. Environmental Protection Agency Maximum Contaminant Level for drinking water of 10 mg/L (milligrams per liter), ranging from 11.3 to 13.5 mg/L. It is unlikely that nitrate concentrations in the aquifer near the Seward west well field are decreased by denitrification in the aquifer due to oxic geochemical conditions that preclude this reaction. Nitrate concentrations coupled with water recharge dates were compared to historical estimated fertilizer application in an attempt to reconstruct historical trends in ground-water nitrate concentrations and their relation to land-use practices. Nitrate concentrations in young-water fractions, after adjustment for mixing, may be decreasing over apparent recharg

Hydrogeology of the D aquifer and movement and ages of ground water determined from geochemical and isotopic analyses, Black Mesa area, northeastern Arizona

USGS Publications Warehouse

Truini, Margot; Longsworth, Steve A.

2003-01-01

The Navajo Nation and the Hopi Tribe in the Black Mesa area depend on ground water from sandstones of the N aquifer for domestic, agricultural, municipal, and industrial needs. They are concerned that pumping of water from the N aquifer will induce leakage from the overlying D aquifer, resulting in the degradation of water quality in the N aquifer. Water samples from the D aquifer contained higher concentrations of dissolved solids than samples from the N aquifer; however, ground waters in the D and N aquifers evolve similarly along their respective flow paths. The ground-water composition in the D aquifer results from interaction with limestone and sandstone sediments. The ground water evolves from a calcium magnesium bicarbonate type in the recharge area to a sodium bicarbonate type in downgradient areas. 34S data indicate sulfate reduction occurs when ground water comes in contact with lignite seams in the Dakota Sandstone. Adjusted 14C ages for ground water in the D aquifer range from 4,000 to 33,000 years. d18O and d2H data indicate that most of the recharge occurred when the climate was cooler and more humid than at present. 3H data indicate that localized recharge has occurred in some areas in recent time. Leakage between the D and N aquifers has been occurring for thousands of years. The area of highest leakage occurs in the southern areas of Black Mesa, where the N aquifer is thin, the predevelopment hydraulic gradient is small, and the vertical head differences between the D and N aquifers are small. Induced leakage from ground-water development in the last several decades could take centuries to detect geochemically because of the increased vertical difference between the potentiometric surfaces of the D and N aquifers, and possibly because of increases in the hydraulic gradient in the N aquifer that would increase flow rates, causing dilution. 87Sr/86Sr data are consistent with the leakage of ground water from the D aquifer into the N aquifer in the southern part of Black Mesa. 87Sr/86Sr values for the N and D aquifers are similar in this area; statistical means are -2.74 ? and -2.49 ?, respectively, N aquifer 87Sr/86Sr values are more radiogenic than D aquifer values in the northern part of Black Mesa; statistical means are -0.14 ? and -2.49 ?, respectively.

Effects of highway deicing chemicals on shallow unconsolidated aquifers in Ohio--final report

USGS Publications Warehouse

Kunze, Allison E.; Sroka, Bernard N.

2004-01-01

As a result of concerns about salt intrusion into drinking water aquifers, the effects of highway deicing chemicals on shallow aquifers were studied at eight locations in Ohio from 1988 through 2002. The study was done by the U.S. Geological Survey, in cooperation with the Ohio Department of Transportation and the Federal Highway Administration. Sites were selected along major undivided highways where drainage is by open ditches and ground-water flow is approximately perpendicular to the highway. Records of deicer application rates were kept, and apparent movement of deicing chemicals through shallow, unconsolidated aquifers was monitored by means of periodic measurements of specific conductance and concentrations of dissolved sodium, calcium, and chloride. The State routes monitored were the following: State Route (SR) 3 in Ashland County, SR 84 in Ashtabula County, SR 29 in Champaign County, SR 4 in Clark County, SR 2 in Lucas County, SR 104 in Pickaway County, SR 14 in Portage County, and SR 97 in Richland County. The study began in 1988 with background data collection, extensive literature review, and site selection. This process, including drilling of wells at numerous test sites and the eight selected sites, lasted 3 years. Routine groundwater sampling at 4- to 6-week intervals began in January 1991 and continued through September 1999. A multilevel, passive flow ground-water sampling device was constructed and used. Other conditions monitored on a regular basis included ground-water level (monitored continuously), specific conductance, air and soil temperature, precipitation,chloride concentration in soil samples, and deicing-chemical application times and rates. Evidence from water analysis, specific-conductance measurements, and surface-geophysical measurements indicates that three of the eight sites (Ashtabula County, Lucas County, and Portage County sites) were affected by direct application of deicing chemicals. Climatic data collected during the study show that cold weather, and therefore deicing-chemical application rates, varied from south to north across the State. As a consequence, only minor traces of dissolved chloride (mean, 2443 mg/L (milligrams per liter)) above background concentrations (mean, 1323 mg/L) were determined in ground-water samples from the southernmost sites (approximately 39?30' to 40? N latitudeChampaign County, Clark County, and Pickaway County). At the Ashland and Richland County sites (approximately 40?30' N latitude), dissolved-chloride concentrations increased above background concentrations only intermittently (mean background concentrations 441 mg/L, rising to a mean of 4056 mg/L in downgradient wells). At the northernmost sites (41? 30' to 42? N latitudeLucas County, Portage County, and Ashtabula County), deicing-chemical application was consistent throughout the winter, and downgradient dissolved-chloride concentrations (mean, 124345 mg/L) rarely returned to background concentrations (mean, 737 mg/L) throughout the study period. Other factors than application rate that may affect the movement of deicing chemicals through an aquifer were precipitation amounts, the types of subsurface materials, ground-water velocity and gradient, hydraulic conductivity, soil type, land use, and Ohio Department of Transportation deicing priority.

Water-quality characteristics and trends for selected sites at and near the Idaho National Laboratory, Idaho, 1949-2009

USGS Publications Warehouse

Bartholomay, Roy C.; Davis, Linda C.; Fisher, Jason C.; Tucker, Betty J.; Raben, Flint A.

2012-01-01

The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, analyzed water-quality data collected from 67 aquifer wells and 7 surface-water sites at the Idaho National Laboratory (INL) from 1949 through 2009. The data analyzed included major cations, anions, nutrients, trace elements, and total organic carbon. The analyses were performed to examine water-quality trends that might inform future management decisions about the number of wells to sample at the INL and the type of constituents to monitor. Water-quality trends were determined using (1) the nonparametric Kendall's tau correlation coefficient, p-value, Theil-Sen slope estimator, and summary statistics for uncensored data; and (2) the Kaplan-Meier method for calculating summary statistics, Kendall's tau correlation coefficient, p-value, and Akritas-Theil-Sen slope estimator for robust linear regression for censored data. Statistical analyses for chloride concentrations indicate that groundwater influenced by Big Lost River seepage has decreasing chloride trends or, in some cases, has variable chloride concentration changes that correlate with above-average and below-average periods of recharge. Analyses of trends for chloride in water samples from four sites located along the Big Lost River indicate a decreasing trend or no trend for chloride, and chloride concentrations generally are much lower at these four sites than those in the aquifer. Above-average and below-average periods of recharge also affect concentration trends for sodium, sulfate, nitrate, and a few trace elements in several wells. Analyses of trends for constituents in water from several of the wells that is mostly regionally derived groundwater generally indicate increasing trends for chloride, sodium, sulfate, and nitrate concentrations. These increases are attributed to agricultural or other anthropogenic influences on the aquifer upgradient of the INL. Statistical trends of chemical constituents from several wells near the Naval Reactors Facility may be influenced by wastewater disposal at the facility or by anthropogenic influence from the Little Lost River basin. Groundwater samples from three wells downgradient of the Power Burst Facility area show increasing trends for chloride, nitrate, sodium, and sulfate concentrations. The increases could be caused by wastewater disposal in the Power Burst Facility area. Some groundwater samples in the southwestern part of the INL and southwest of the INL show concentration trends for chloride and sodium that may be influenced by wastewater disposal. Some of the groundwater samples have decreasing trends that could be attributed to the decreasing concentrations in the wastewater from the late 1970s to 2009. The young fraction of groundwater in many of the wells is more than 20 years old, so samples collected in the early 1990s are more representative of groundwater discharged in the 1960s and 1970s, when concentrations in wastewater were much higher. Groundwater sampled in 2009 would be representative of the lower concentrations of chloride and sodium in wastewater discharged in the late 1980s. Analyses of trends for sodium in several groundwater samples from the central and southern part of the eastern Snake River aquifer show increasing trends. In most cases, however, the sodium concentrations are less than background concentrations measured in the aquifer. Many of the wells are open to larger mixed sections of the aquifer, and the increasing trends may indicate that the long history of wastewater disposal in the central part of the INL is increasing sodium concentrations in the groundwater.

Groundwater and surface-water interactions near White Bear Lake, Minnesota, through 2011

USGS Publications Warehouse

Jones, Perry M.; Trost, Jared J.; Rosenberry, Donald O.; Jackson, P. Ryan; Bode, Jenifer A.; O'Grady, Ryan M.

2013-01-01

The U.S. Geological Survey, in cooperation with the White Bear Lake Conservation District, the Minnesota Pollution Control Agency, the Minnesota Department of Natural Resources, and other State, county, municipal, and regional planning agencies, watershed organizations, and private organizations, conducted a study to characterize groundwater and surface-water interactions near White Bear Lake through 2011. During 2010 and 2011, White Bear Lake and other lakes in the northeastern part of the Twin Cities Metropolitan Area were at historically low levels. Previous periods of lower water levels in White Bear Lake correlate with periods of lower precipitation; however, recent urban expansion and increased pumping from the Prairie du Chien-Jordan aquifer have raised the question of whether a decline in precipitation is the primary cause for the recent water-level decline in White Bear Lake. Understanding and quantifying the amount of groundwater inflow to a lake and water discharge from a lake to aquifers is commonly difficult but is important in the management of lake levels. Three methods were used in the study to assess groundwater and surface-water interactions on White Bear Lake: (1) a historical assessment (1978-2011) of levels in White Bear Lake, local groundwater levels, and their relation to historical precipitation and groundwater withdrawals in the White Bear Lake area; (2) recent (2010-11) hydrologic and water-quality data collected from White Bear Lake, other lakes, and wells; and (3) water-balance assessments for White Bear Lake in March and August 2011. An analysis of covariance between average annual lake-level change and annual precipitation indicated the relation between the two variables was significantly different from 2003 through 2011 compared with 1978 through 2002, requiring an average of 4 more inches of precipitation per year to maintain the lake level. This shift in the linear relation between annual lake-level change and annual precipitation indicated the net effect of the non-precipitation terms on the water balance has changed relative to precipitation. The average amount of precipitation required each year to maintain the lake level has increased from 33 inches per year during 1978-2002 to 37 inches per year during 2003-11. The combination of lower precipitation and an increase in groundwater withdrawals can explain the change in the lake-level response to precipitation. Annual and summer groundwater withdrawals from the Prairie du Chien-Jordan aquifer have more than doubled from 1980 through 2010. Results from a regression model constructed with annual lake-level change, annual precipitation minus evaporation, and annual volume of groundwater withdrawn from the Prairie du Chien-Jordan aquifer indicated groundwater withdrawals had a greater effect than precipitation minus evaporation on water levels in the White Bear Lake area for all years since 2003. The recent (2003-11) decline in White Bear Lake reflects the declining water levels in the Prairie du Chien-Jordan aquifer; increases in groundwater withdrawals from this aquifer are a likely cause for declines in groundwater levels and lake levels. Synoptic, static groundwater-level and lake-level measurements in March/April and August 2011 indicated groundwater was potentially flowing into White Bear Lake from glacial aquifers to the northeast and south, and lake water was potentially discharging from White Bear Lake to the underlying glacial and Prairie du Chien-Jordan aquifers and glacial aquifers to the northwest. Groundwater levels in the Prairie du Chien-Jordan aquifer below White Bear Lake are approximately 0 to 19 feet lower than surface-water levels in the lake, indicating groundwater from the aquifer likely does not flow into White Bear Lake, but lake water may discharge into the aquifer. Groundwater levels from March/April to August 2011 declined more than 10 feet in the Prairie du Chien-Jordan aquifer south of White Bear Lake and to the north in Hugo, Minnesota. Water-quality analyses of pore water from nearshore lake-sediment and well-water samples, seepage-meter measurements, and hydraulic-head differences measured in White Bear Lake also indicated groundwater was potentially flowing into White Bear Lake from shallow glacial aquifers to the east and south. Negative temperature anomalies determined in shallow waters in the water-quality survey conducted in White Bear Lake indicated several shallow-water areas where groundwater may be flowing into the lake from glacial aquifers below the lake. Cool lake-sediment temperatures (less than 18 degrees Celsius) were measured in eight areas along the northeast, east, south, and southwest shores of White Bear Lake, indicating potential areas where groundwater may flow into the lake. Stable isotope analyses of well-water, precipitation, and lake-water samples indicated wells downgradient from White Bear Lake screened in the glacial buried aquifer or open to the Prairie du Chien-Jordan aquifer receive a mixture of surface water and groundwater; the largest surface-water contributions are in wells closer to White Bear Lake. A wide range in oxygen-18/oxygen-16 and deuterium/protium ratios was measured in well-water samples, indicating different sources of water are supplying water to the wells. Well water with oxygen-18/oxygen-16 and deuterium/protium ratios that plot close to the meteoric water line consisted mostly of groundwater because deuterium/protium ratios for most groundwater usually are similar to ratios for rainwater and snow, plotting close to meteoric water lines. Well water with oxygen-18/oxygen-16 and deuterium/protium ratios that plot between the meteoric water line and ratios for the surface-water samples from White Bear Lake consists of a mixture of surface water and groundwater; the percentage of each source varies relative to its ratios. White Bear Lake is the likely source of the surface water to the wells that have a mixture of surface water and groundwater because (1) it is the only large, deep lake near these wells; (2) these wells are near and downgradient from White Bear Lake; and (3) these wells obtain their water from relatively deep depths, and White Bear Lake is the deepest lake in that area. The percentages of surface-water contribution to the three wells screened in the glacial buried aquifer receiving surface water were 16, 48, and 83 percent. The percentages of surface-water contribution ranged from 5 to 79 percent for the five wells open to the Prairie du Chien-Jordan aquifer receiving surface water; wells closest to White Bear Lake had the largest percentages of surface-water contribution. Water-balance analysis of White Bear Lake in March and August 2011 indicated a potential discharge of 2.8 and 4.5 inches per month, respectively, over the area of the lake from the lake to local aquifers. Most of the sediments from a 12.4-foot lake core collected at the deepest part of White Bear Lake consisted of silts, sands, and gravels likely slumped from shallower waters, with a very low amount of low-permeability, organic material.

Geohydrology, Geochemistry, and Ground-Water Simulation-Optimization of the Central and West Coast Basins, Los Angeles County, California

USGS Publications Warehouse

Reichard, Eric G.; Land, Michael; Crawford, Steven M.; Johnson, Tyler D.; Everett, Rhett; Kulshan, Trayle V.; Ponti, Daniel J.; Halford, Keith L.; Johnson, Theodore A.; Paybins, Katherine S.; Nishikawa, Tracy

2003-01-01

Historical ground-water development of the Central and West Coast Basins in Los Angeles County, California through the first half of the 20th century caused large water-level declines and induced seawater intrusion. Because of this, the basins were adjudicated and numerous ground-water management activities were implemented, including increased water spreading, construction of injection barriers, increased delivery of imported water, and increased use of reclaimed water. In order to improve the scientific basis for these water management activities, an extensive data collection program was undertaken, geohydrological and geochemical analyses were conducted, and ground-water flow simulation and optimization models were developed. In this project, extensive hydraulic, geologic, and chemical data were collected from new multiple-well monitoring sites. On the basis of these data and data compiled and collected from existing wells, the regional geohydrologic framework was characterized. For the purposes of modeling, the three-dimensional aquifer system was divided into four aquifer systems?the Recent, Lakewood, Upper San Pedro, and Lower San Pedro aquifer systems. Most pumpage in the two basins is from the Upper San Pedro aquifer system. Assessment of the three-dimensional geochemical data provides insight into the sources of recharge and the movement and age of ground water in the study area. Major-ion data indicate the chemical character of water containing less than 500 mg/L dissolved solids generally grades from calcium-bicarbonate/sulfate to sodium bicarbonate. Sodium-chloride water, high in dissolved solids, is present in wells near the coast. Stable isotopes of oxygen and hydrogen provide information on sources of recharge to the basin, including imported water and water originating in the San Fernando Valley, San Gabriel Valley, and the coastal plain and surrounding hills. Tritium and carbon-14 data provide information on relative ground-water ages. Water with abundant tritium (greater than 8 tritium units) is found in and downgradient from the Montebello Forebay and near the seawater barrier projects, indicating recent recharge. Water with less than measurable tritium is present in, and downgradient from, the Los Angeles Forebay and in most wells in the West Coast Basin. Water from several deep wells was analyzed for carbon-14. Uncorrected estimates of age for these samples range from 600 to more than 20,000 years before present. Chemical and isotopic data are combined to evaluate changes in chemical character along flow paths emanating from the Montebello and Los Angeles Forebays. A four-layer ground-water flow model was developed to simulate steady-state ground-water conditions representative of those in 1971 and transient conditions for the period 1971?2000. Model results indicate increases in ground-water storage in all parts of the study area over the simulated thirty-year period. The model was used to develop a three-dimensional ground-water budget and to assess impacts of two alternative future (2001?25) ground-water development scenarios?one that assumes continued pumping at average current rates and a second that assumes increasing pumping from most wells in the Central Basin. The model simulates stable or slightly increasing water levels for the first scenario and declining water levels (25 to 50 ft in the Central Basin) in the second scenario. Model sensitivity to parameter values and to the assumed Orange County boundary condition was evaluated. Particle tracking was applied to simulate advective transport of water from the spreading ponds, the coastline, and the seawater injection barriers. Particle tracking results indicate that most flow within the Upper San Pedro aquifer system occurs within about 20 percent of the total aquifer system thickness and that virtually all water injected into the seawater barrier projects has flowed inland. The simulation model was linked with optimizatio

High (36)Cl/Cl ratios in Chernobyl groundwater.

PubMed

Roux, Céline; Le Gal La Salle, Corinne; Simonucci, Caroline; Van Meir, Nathalie; Fifield, L Keith; Diez, Olivier; Bassot, Sylvain; Simler, Roland; Bugai, Dmitri; Kashparov, Valery; Lancelot, Joël

2014-12-01

After the explosion of the Chernobyl Nuclear Power Plant in April 1986, contaminated material was buried in shallow trenches within the exclusion zone. A (90)Sr plume was evidenced downgradient of one of these trenches, trench T22. Due to its conservative properties, (36)Cl is investigated here as a potential tracer to determine the maximal extent of the contamination plume from the trench in groundwater. (36)Cl/Cl ratios measured in groundwater, trench soil water and leaf leachates are 1-5 orders of magnitude higher than the theoretical natural (36)Cl/Cl ratio. This contamination occurred after the Chernobyl explosion and currently persists. Trench T22 acts as an obvious modern point source of (36)Cl, however other sources have to be involved to explain such contamination. (36)Cl contamination of groundwater can be explained by dilution of trench soil water by uncontaminated water (rainwater or deep groundwater). With a plume extending further than that of (90)Sr, radionuclide which is impacted by retention and decay processes, (36)Cl can be considered as a suitable tracer of contamination from the trench in groundwater provided that modern release processes of (36)Cl from trench soil are better characterized. Copyright © 2014 Elsevier Ltd. All rights reserved.

Remediation of a uranium-contamination in ground water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woerner, Joerg; Margraf, Sonja; Hackel, Walter

2007-07-01

The former production site of NUKEM where nuclear fuel-elements were developed and handled from 1958 to 1988 was situated in the centre of an industrial park for various activities of the chemical and metallurgical industry. The size of the industrially used part is about 300.000 m{sup 2}. Regulatory routine controls showed elevated CHC (Chlorinated Hydro-Carbons) values of the ground water at the beginning of the 1990's in an area which represented about 80.000 m{sup 2} down-gradient of locations where CHC compounds were stored and handled. Further investigations until 1998 proved that former activities on the NUKEM site, like the UF{submore » 6} conversion process, were of certain relevance. The fact that several measured values were above the threshold values made the remediation of the ground water mandatory. This was addressed in the permission given by the Ministry for Nuclear Installations and Environment of Hesse according to chap. 7 of the German atomic law in October 2000. Ground water samples taken in an area of about 5.000 m{sup 2} showed elevated values of total Uranium activity up to between 50 and 75 Bq/l in 2002. Furthermore in an area of another 20.000 m{sup 2} the samples were above threshold value. In this paper results of the remediation are presented. The actual alpha-activities of the ground waters of the remediation wells show values of 3 to 9 Bq/l which are dominated by 80 to 90 % U-234 activity. The mass-share of total Uranium for this nuclide amounts to 0,05% on average. The authority responsible for conventional water utilisation defined target values for remediation: 20 {mu}g/l for dissolved Uranium and 10 {mu}g/l for CHC. Both values have not yet been reached for an area of about 10.000 m{sup 2}. The remediation process by extracting water from four remediation wells has proved its efficiency by reduction of the starting concentrations by a factor of 3 to 6. Further pumping will be necessary especially in that area of the site where the contaminations were found later during soil remediation activities. Only two wells have been in operation since July 2002 when the remediation technique was installed and an apparatus for direct gamma-spectroscopic measurement of the accumulated activities on the adsorbers was qualified. Two further remediation wells have been in operation since August 2006, when the installed remediation technique was about to be doubled from a throughput of 5 m{sup 3}/h to 10 m{sup 3}/h. About 20.000 m{sup 3} of ground water have been extracted since from these two wells and the decrease of their Uranium concentrations behaves similar to that of the two other wells being extracted since the beginning of remediation. Both, total Uranium-concentrations and the weight-share of the nuclides U-234, U-235 and U-238 are measured by ICP-MS (Inductively Coupled Plasma - Mass Spectrometry) besides measurements of Uranium-Alpha-Activities in addition to the measurement of CHC components of which PCE (Per-chlor-Ethene) is dominant in the contaminated area. CHC compounds are measured by GC (Gas Chromatography). Down-gradient naturally attenuated products are detected in various compositions. Overall 183.000 m{sup 3} of ground water have been extracted. Using a pump and treat method 11 kg Uranium have been collected on an ion-exchange material based on cellulose, containing almost 100 MBq U-235 activity, and almost 15 kg of CHC, essentially PCE, were collected on GAC (Granules of Activated Carbon). Less than 3% of the extracted Uranium have passed the adsorber-system of the remediation plant and were adsorbed by the sewage sludge of the industrial site's waste water treatment. The monthly monitoring of 19 monitoring wells shows that an efficient artificial barrier was built up by the water extraction. The Uranium contamination of two ground water plumes has drastically been reduced by the used technique dependent on the amounts of extracted water. The concentration of the CHC contamination has changed depending on the location of temporal pumping. Thereby maximum availability of this contaminant for the remediation process is ensured. If locations with unchanged water quality are detected electrochemical parameters of the water or hydro-geologic data of the aquifer have to be taken into further consideration to improve the process of remediation. (authors)« less

Remediating Contaminant Plumes in Groundwater with Shallow Excavations Containing Coarse Reactive Media.

PubMed

Hudak, Paul F

2018-02-01

A groundwater flow and mass transport model tested the capability of shallow excavations filled with coarse, reactive media to remediate a hypothetical unconfined aquifer with a maximum saturated thickness of 5 m. Modeled as contaminant sinks, the rectangular excavations were 10 m downgradient of an initial contaminant plume originating from a source at the top of the aquifer. The initial plume was approximately 259 m long, 23 m wide, and 5 m thick, with a downgradient tip located approximately 100 m upgradient of the site boundary. The smallest trench capable of preventing offsite migration was 11 m long (measured perpendicular to groundwater flow), 4 m wide (measured parallel to groundwater flow), and 3 m deep. Results of this study suggest that shallow trenches filled with coarse filter media that partially penetrate unconfined aquifers may be a viable alternative for remediating contaminated groundwater at some sites.

Karst hydrology and chemical contamination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, M.S.

1993-01-01

Ground-water flow in karst aquifers is very different from flow in granular or fractured aquifers. Chemical contamination may be fed directly to a karst aquifer via overland flow to a sinkhole with little or no attenuation and may contaminate downgradient wells, springs, and sinkholes within a few hours or a few days. Contaminants may also become temporarily stored in the epikarstic zone for eventual release to the aquifer. Flood pulses may flush the contaminants to cause transiently higher levels of contamination in the aquifer and discharge points. The convergent nature of flow in karst aquifers may result in contaminants becomingmore » concentrated in conduits. Once contaminants have reached the subsurface conduits, they are likely to be rapidly transported to spring outlets. Traditional aquifer remediation techniques for contaminated aquifers are less applicable to karst aquifers.« less

Simulation of ground-water flow in the Potomac-Raritan-Magothy aquifer system, Pennsauken Township and vicinity, New Jersey

USGS Publications Warehouse

Pope, Daryll A.; Watt, Martha K.

2004-01-01

The Potomac-Raritan-Magothy aquifer system is one of the primary sources of potable water in the Coastal Plain of New Jersey, particularly in heavily developed areas along the Delaware River. In Pennsauken Township, Camden County, local drinking-water supplies from this aquifer system have been contaminated by hexavalent chromium at concentrations that exceed the New Jersey maximum contaminant level. In particular, ground water at the Puchack well field has been adversely affected to the point where, since 1984, water is no longer withdrawn from this well field for public supply. The area that contains the Puchack well field was added to the National Priorities List in 1998 as a Superfund site. The U.S. Geological Survey (USGS) conducted a reconnaissance study from 1996 to 1998 during which hydrogeologic and water-quality data were collected and a ground-water-flow model was developed to describe the conditions in the aquifer system in the Pennsauken Township area. The current investigation by the USGS, in cooperation with the U.S. Environmental Protection Agency (USEPA), is an extension of the previous study. Results of the current study can be applied to a Remedial Investigation and Feasibility Study conducted at the Puchack well field Superfund site. The USGS study collected additional data on the hydrogeology and water-quality in the area. These data were incorporated into a refined model of the ground-water-flow system in the Potomac-Raritan-Magothy aquifer system. A finite-difference model was developed to simulate ground-water flow and the advective transport of chromium-contaminated ground water in the aquifers of the Potomac-Raritan-Magothy aquifer system in the Pennsauken Township area. An 11-layer model was used to represent the complex hydrogeologic framework. The model was calibrated using steady-state water-level data from March 1998, April 1998, and April 2001. Water-level recovery during the shutdown of Puchack 1 during March to April 1998 was simulated to evaluate model performance in relation to changing stresses. The Delaware River contributes appreciable-flow to the ground-water system from areas where the Middle and Lower aquifers crop out beneath the river. A transient simulation of an aquifer test near the Delaware River was run to help characterize the hydraulic conductivity of the riverbed sediments represented in the model. Vertical flow across confining units between the aquifers is highly variable and is important in the movement of water and associated contaminants through the flow system. The model was imbedded within a regional model of the Potomac-Raritan-Magothy aquifer system in Camden County. In general, a simulation of baseline conditions, which can provide a representation on which simulations of various alternatives can be based for the feasibility study, incorporated average conditions from 1998 to 2000. Ground-water withdrawals within the model area during this period averaged about 14 Mgal/d. Regional ground-water flow is from recharge areas and from the Delaware River to downgradient pumped wells located just east of the model area in central Camden County. Simulation results show an important connection between the Intermediate sand and the Lower aquifer of the Potomac-Raritan-Magothy aquifer system in the vicinity of the chromium-contaminated area. The Delaware River contributes nearly 10 Mgal/d to the flow system, whereas recharge contributes about 6 Mgal/d. Ground-water withdrawals within the model area account for nearly 14 Mgal/d (mostly from the Lower aquifer of the Potomac-Raritan-Magothy aquifer system).

Waste-water characterization and hazardous-waste technical assistance survey, Mather AFB California. Final report, 28 November-9 December 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, S.P.; Hedgecock, N.S.

1989-10-01

Personnel from the AFOEHL conducted a waste-water characterization and hazardous-waste technical assistance survey at MAFB from 28 Nov to 9 Dec 1988. The scope of this survey was to characterize the waste-water, address hazardous-waste-management practices, and explore opportunities for hazardous waste minimization. The waste water survey team analyzed the base's industrial effluent, effluent from oil/water separators, and storm water. The team performed a shop-by-shop evaluation of chemical-waste-management practices. Survey results showed that MAFB needs to improve its hazardous-waste-management program. Recommendations for improvement include: (1) Collecting two additional grab samples on separate days from the hospital discharge. Analyze for EPA Methodmore » 601 to determine if the grab sample from the survey gives a true indication of what is being discharged. (2) Locate the source and prevent mercury from the hospital from discharging into the sanitary sewer. (3) Dilute the soaps used for cleaning at the Fuels Lab, Building 7060. (4) Investigate the source of chromium from the Photo Lab. (5) Clean out the sewer system manhole directly downgradient from the Photo Lab. (6) Locate the source of contamination in the West Ditch Outfall. (7) Reconnect the two oil/water separators that discharge into the storm sewerage system. (8) Investigate the source of methylene chloride coming on the base. (9) Investigate the source of mercury at Fuel Cell Repair, building 7005.« less

Description and hydrogeologic evaluation of nine hazardous-waste sites in Kansas, 1984-86

USGS Publications Warehouse

Hart, R.J.; Spruill, T.B.

1988-01-01

Wastes generated at nine hazardous-waste sites in Kansas were disposed in open pits, 55-gal drums, or large storage tanks. These disposal methods have the potential to contaminate groundwater beneath the sites, the soil on the sites, and nearby surface water bodies. Various activities on the nine sites included production of diborane, transformer oil waste, production of soda ash, use of solvents for the manufacture of farm implements, reclamation of solvents and paints, oil-refinery wastes, meat packaging, and the manufacture and cleaning of tanker-truck tanks. Monitoring wells were installed upgradient and downgradient from the potential contamination source on each site. Strict decontamination procedures were followed to prevent cross contamination between well installations. Air-quality surveys were made on each site before other investigative procedures started. Hydrogeologic investigative techniques, such as terrain geophysical surveys, gamma-ray logs, and laboratory permeameter tests, were used. Groundwater level measurements provide data to determine the direction of flow. Groundwater contamination detected under the sites posed the greatest threat to the environment because of possible migration of contaminants by groundwater flow. Concentrations of volatile organic compounds, polynuclear aromatic hydrocarbons, and trace metals were detected in the groundwater at several of the sites. Many of the same compounds detected in the groundwater also were detected in soil and bed-material samples collected onsite or adjacent to the sites. Several contaminants were detected in background samples of groundwater and soil. (USGS)

Meteorological Influences on Nitrogen Dynamics of a Coastal Onsite Wastewater Treatment System

PubMed Central

O’Driscoll, M.A.; Humphrey, C. P.; Deal, N.E.; Lindbo, D.L.; Zarate-Bermudez, M.A.

2016-01-01

Onsite wastewater treatment systems (OWTS) can contribute nitrogen (N) to coastal waters. In coastal areas with shallow groundwater, OWTS are likely affected by meteorological events. However, the meteorological influences on temporal variability of N exports from OWTS are not well documented. Hydrogeological characterization and seasonal monitoring of wastewater and groundwater quality were conducted at a residence adjacent to the Pamlico River Estuary, North Carolina during a two-year field study (October 2009–2011). Rainfall was elevated during the first study year, relative to the annual mean. In the second year, drought was followed by extreme precipitation from Hurricane Irene. Recent meteorological conditions influenced N speciation and concentrations in groundwater. Groundwater total dissolved nitrogen (TDN) beneath the OWTS drainfield was dominated by nitrate during the drought; during wetter periods ammonium and organic N were common. Effective precipitation (P-ET) affected OWTS TDN exports because of its influence on groundwater recharge and discharge. Groundwater nitrate-N concentrations beneath the drainfield were typically higher than 10 mg/l when total bi-weekly precipitation was less than evapotranspiration (precipitation deficit: P15 m downgradient of the drainfield. Although OWTS nitrate inputs caused elevated groundwater nitrate concentrations between the drainfield and the estuary, the majority of nitrate was attenuated via denitrification between the OWTS and 48 m to the estuary. However, DON originating from the OWTS was mobile and contributed to elevated TDN concentrations along the groundwater flowpath to the estuary. PMID:25602204

Arsenic Movement From Sediment to Water: Microbes and Mobilization in a Contaminated Lake

NASA Astrophysics Data System (ADS)

Keimowitz, A. R.; Mailloux, B. J.; Chillrud, S. N.; Ross, J.; Wovkulich, K.; McNamara, P.; Alexandrova, E.; Thompson, L.

2008-12-01

Union Lake (Millville, NJ), a reservoir downstream from the Vineland Chemical Company Superfund site, has bottom sediments that are highly contaminated with arsenic (>1 g/kg). Offsite As transport was investigated. Because the lake is a result of damming, it is perched above the water table and therefore As transport may occur via downward movement of porewaters and/or groundwaters. Preliminary evidence for this was found in the form of iron flocculates enriched in As which were found in surface seeps downgradient of the dam. The possibility of As remobilization and/or off-site transport by seasonal anoxia of lake bottom- waters was also explored. Although historically, appreciable As was found in the water column of the lake (up to approximately 200 micrograms/L), As releases over the summers of 2007 and 2008 were negligible to modest with a maximum [As] of 23 micrograms/L. Arsenic mobilization from the contaminated sediments into surface waters of the reservoir are limited in part due to incomplete eutrophication and frequent overturning (approximately 1x/month in summer 2007) of this shallow lake, therefore conditions which promoted greater As release were explored in the laboratory. Field and laboratory samples were examined for changes in the microbial community using a variety of genetic techniques; these changes in microbial community were both a result of, and influenced, seasonal lake cycles.

Changes in ground-water quality in the Canal Creek Aquifer between 1995 and 2000-2001, West Branch Canal Creek area, Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Phelan, Daniel J.; Fleck, William B.; Lorah, Michelle M.; Olsen, Lisa D.

2002-01-01

Since 1917, Aberdeen Proving Ground, Maryland has been the primary chemical-warfare research and development center for the U.S. Army. Ground-water contamination has been documented in the Canal Creek aquifer because of past disposal of chemical and ordnance manufacturing waste. Comprehensive sampling for volatile organic compounds in ground water by the U.S. Geological Survey in the West Branch Canal Creek area was done in June?October 1995 and June?August 2000. The purpose of this report is (1) to compare volatile organic compound concentrations and determine changes in the ground-water contaminant plumes along two cross sections between 1995 and 2000, and (2) to incorporate data from new piezometers sampled in spring 2001 into the plume descriptions. Along the southern cross section, total concentrations of volatile organic compounds in 1995 were determined to be highest in the landfill area east of the wetland (5,200 micrograms per liter), and concentrations were next highest deep in the aquifer near the center of the wetland (3,300 micrograms per liter at 35 feet below land surface). When new piezometers were sampled in 2001, higher carbon tetrachloride and chloroform concentrations (2,000 and 2,900 micrograms per liter) were detected deep in the aquifer 38 feet below land surface, west of the 1995 sampling. A deep area in the aquifer close to the eastern edge of the wetland and a shallow area just east of the creek channel showed declines in total volatile organic compound concentrations of more than 25 percent, whereas between those two areas, con-centrations generally showed an increase of greater than 25 percent between 1995 and 2000. Along the northern cross section, total concentrations of volatile organic compounds in ground water in both 1995 and 2000 were determined to be highest (greater than 2,000 micrograms per liter) in piezometers located on the east side of the section, farthest from the creek channel, and concentrations were progressively lower at piezometer locations closer to the creek channel. Total volatile organic compound concentrations increased more than 25 percent in some areas in the middle depths of the aquifer; however, it could not be determined if a defined plume was moving farther downgradient along ground-water flow paths toward the creek channel, or vertically downward because of density differences within the aquifer.

Mercury accumulation by lower trophic-level organisms in lentic systems within the Guadalupe River watershed, California

USGS Publications Warehouse

Kuwabara, James S.; Topping, Brent R.; Moon, Gerald E.; Husby, Peter; Lincoff, Andrew; Carter, James L.; Croteau, Marie-Noële

2005-01-01

The water columns of four reservoirs (Almaden, Calero, Guadalupe and Lexington Reservoirs) and an abandoned quarry pit filled by Alamitos Creek drainage for recreational purposes (Lake Almaden) were sampled on September 14 and 15, 2004 to provide the first measurements of mercury accumulation by phytoplankton and zooplankton in lentic systems (bodies of standing water, as in lakes and reservoirs) within the Guadalupe River watershed, California. Because of widespread interest in ecosystem effects associated with historic mercury mining within and downgradient of the Guadalupe Riverwatershed, transfer of mercury to lower trophic-level organisms was examined. The propensity of mercury to bioaccumulate, particularly in phytoplankton and zooplankton at the base of the food web, motivated this attempt to provide information in support of developing trophic-transfer and solute-transport models for the watershed, and hence in support of subsequent evaluation of load-allocation strategies. Both total mercury and methylmercury were examined in these organisms. During a single sampling event, replicate samples from the reservoir water column were collected and processed for dissolved-total mercury, dissolved-methylmercury, phytoplankton mercury speciation, phytoplankton taxonomy and biomass, zooplankton mercury speciation, and zooplankton taxonomy and biomass. The timing of this sampling event was coordinated with sampling and analysis of fish from these five water bodies, during a period of the year when vertical stratification in the reservoirs generates a primary source of methylmercury to the watershed. Ancillary data, including dissolved organic carbon and trace-metal concentrations as well as vertical profiles of temperature, dissolved oxygen, specific conductance and pH, were gathered to provide a water-quality framework from which to compare the results for mercury. This work, in support of the Guadalupe River Mercury Total Maximum Daily Load (TMDL) Study, provides the first measurements of mercury trophic transfer through planktonic communities in this watershed. It is worth reemphasizing that this data set represents a single ?snap shot? of conditions in water bodies within the Guadalupe River watershed to: (1) fill gaps in trophic transfer information, and (2) provide a scientific basis for future process-based studies with enhanced temporal and spatial coverage. This electronic document was unconventionally formatted to enhance the accessibility of information to a wide range of interest groups.

Effects of surface applications of biosolids on soil, crops, ground water, and streambed sediment near Deer Trail, Colorado, 1999-2003

USGS Publications Warehouse

Yager, Tracy J.B.; Smith, David B.; Crock, James G.

2004-01-01

The U.S. Geological Survey, in cooperation with Metro Wastewater Reclamation District and North Kiowa Bijou Groundwater Management District, studied natural geochemical effects and the effects of biosolids applications to the Metro Wastewater Reclamation District properties near Deer Trail, Colorado, during 1999 through 2003 because of public concern about potential contamination of soil, crops, ground water, and surface water from biosolids applications. Parameters analyzed for each monitoring component included arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, and zinc (the nine trace elements regulated by Colorado for biosolids), gross alpha and gross beta radioactivity, and plutonium, as well as other parameters. Concentrations of the nine regulated trace elements in biosolids were relatively uniform and did not exceed applicable regulatory standards. All plutonium concentrations in biosolids were below the minimum detectable level and were near zero. The most soluble elements in biosolids were arsenic, molybdenum, nickel, phosphorus, and selenium. Elevated concentrations of bismuth, mercury, phosphorus, and silver would be the most likely inorganic biosolids signature to indicate that soil or streambed sediment has been affected by biosolids. Molybdenum and tungsten, and to a lesser degree antimony, cadmium, cobalt, copper, mercury, nickel, phosphorus, and selenium, would be the most likely inorganic 'biosolids signature' to indicate ground water or surface water has been affected by biosolids. Soil data indicate that biosolids have had no measurable effect on the concentration of the constituents monitored. Arsenic concentrations in soil of both Arapahoe and Elbert County monitoring sites (like soil from all parts of Colorado) exceed the Colorado soil remediation objectives and soil cleanup standards, which were determined by back-calculating a soil concentration equivalent to a one-in-a-million cumulative cancer risk. Lead concentrations in soil slightly exceed the U.S. Environmental Protection Agency toxicity-derived ecological soil-screening levels for avian wildlife. Plutonium concentration in the soil was near zero. Wheat-grain data were insufficient to determine any measurable effects from biosolids. Comparison with similar data from other parts of North America where biosolids were not applied indicates similar concentrations. However, the Deer Trail study area had higher nickel concentrations in wheat from both the biosolids-applied fields and the control fields. Plutonium content of the wheat was near zero. Ground-water levels generally declined at most wells during 1999 through 2003. Ground-water quality did not correlate with ground-water levels. Vertical ground-water gradients during 1999 through 2003 indicate that bedrock ground-water resources downgradient from the biosolids-applied areas are not likely to be contaminated by biosolids applications unless the gradients change as a result of pumping. Ground-water quality throughout the study area varied over time at each site and from site to site at the same time, but plutonium concentrations in the ground water always were near zero. Inorganic concentrations at well D6 were relatively high compared to other ground-water sites studied. Ground-water pH and concentrations of fluoride, nitrite, aluminum, arsenic, barium, chromium, cobalt, copper, lead, mercury, nickel, silver, zinc, and plutonium in the ground water of the study area met Colorado standards. Concentrations of chloride, sulfate, nitrate, boron, iron, manganese, and selenium exceeded Colorado ground-water standards at one or more wells. Nitrate concentrations at well D6 significantly (alpha = 0.05) exceeded the Colorado regulatory standard. Concentrations of arsenic, cadmium, chromium, lead, mercury, nickel, and zinc in ground water had no significant (alpha = 0.05) upward trends. During 1999-2003, concentrations of nitrate, copper, molybdenum, and selenium

Effects of solid-liquid separation and storage on monensin attenuation in dairy waste management systems.

PubMed

Hafner, Sarah C; Watanabe, Naoko; Harter, Thomas; Bergamaschi, Brian A; Parikh, Sanjai J

2017-04-01

Environmental release of veterinary pharmaceuticals has been of regulatory concern for more than a decade. Monensin is a feed additive antibiotic that is prevalent throughout the dairy industry and is excreted in dairy waste. This study investigates the potential of dairy waste management practices to alter the amount of monensin available for release into the environment. Analysis of wastewater and groundwater from two dairy farms in California consistently concluded that monensin is most present in lagoon water and groundwater downgradient of lagoons. Since the lagoons represent a direct source of monensin to groundwater, the effect of waste management, by mechanical screen separation and lagoon aeration, on aqueous monensin concentration was investigated through construction of lagoon microcosms. The results indicate that monensin attenuation is not improved by increased solid-liquid separation prior to storage in lagoons, as monensin is rapidly desorbed after dilution with water. Monensin is also shown to be easily degraded in lagoon microcosms receiving aeration, but is relatively stable and available for leaching under typical anaerobic lagoon conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Superfund Record of Decision (EPA Region 5): New Brighton/Arden Hills (TCAAP), Twin Cities Army Ammunition Plant, MN. (Seventh remedial action), August 1989

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1989-08-11

The New Brighton/Arden Hills site, also known as the Twin Cities Army Ammunition Plant (TCAAP) site, is in New Brighton, Minnesota. Past disposal of ammunition manufacturing wastes onsite resulted in contamination of ground water beneath and downgradient of the site. A total of 14 waste-disposal locations have been identified and assigned as Sites A through K. During remedial investigations at Site D, soil was discovered to be contaminated with PCBs and other organic and metal contaminants. A soil-gas extraction system was implemented to remove the source of volatile organic contamination and reduce the potential of migration to ground water. Inmore » implementing the soil gas extraction system, PCB-contaminated soil was removed, stockpiled near Site D, and sealed with a plastic-liner material. The interim remedy addresses the treatment and disposal of contaminated soil that is stockpiled near Site D. The primary contaminants of concern affecting the soil are VOCs including TCE and PCE, other organics including PCBs, and metals including arsenic and lead.« less

Effects of solid-liquid separation and storage on monensin attenuation in dairy waste management systems

USGS Publications Warehouse

Hafner, Sarah C.; Watanabe, Naoko; Harter, Thomas; Bergamaschi, Brian; Parikh, Sanjai J.

2017-01-01

Environmental release of veterinary pharmaceuticals has been of regulatory concern for more than a decade. Monensin is a feed additive antibiotic that is prevalent throughout the dairy industry and is excreted in dairy waste. This study investigates the potential of dairy waste management practices to alter the amount of monensin available for release into the environment. Analysis of wastewater and groundwater from two dairy farms in California consistently concluded that monensin is most present in lagoon water and groundwater downgradient of lagoons. Since the lagoons represent a direct source of monensin to groundwater, the effect of waste management, by mechanical screen separation and lagoon aeration, on aqueous monensin concentration was investigated through construction of lagoon microcosms. The results indicate that monensin attenuation is not improved by increased solid-liquid separation prior to storage in lagoons, as monensin is rapidly desorbed after dilution with water. Monensin is also shown to be easily degraded in lagoon microcosms receiving aeration, but is relatively stable and available for leaching under typical anaerobic lagoon conditions.

Effect of sewage sludge on formation of acidic ground water at a reclaimed coal mine

USGS Publications Warehouse

Cravotta, C.A.

1998-01-01

Data on rock, ground water, vadose water, and vadose gas chemistry were collected for two years after sewage sludge was applied at a reclaimed surface coal mine in Pennsylvania to determine if surface-applied sludge is an effective barrier to oxygen influx, contributes metals and nutrients to ground water, and promotes the acidification of ground water. Acidity, sulfate, and metals concentrations were elevated in the ground water (6- to 21-m depth) from spoil relative to unmined rock because of active oxidation of pyrite and dissolution of aluminosilicate, carbonate, and Mn-Fe-oxide minerals in the spoil. Concentrations of acidity, sulfate, metals (Fe, Mn, Al, Cd, Cu, Cr, Ni, Zn), and nitrate, and abundances of iron-oxidizing bacteria were elevated in the ground water from sludge-treated spoil relative to untreated spoil having a similar mineral composition; however, gaseous and dissolved oxygen concentrations did not differ between the treatments. Abundances of iron-oxidizing bacteria in the ground water samples were positively correlated with concentrations of ammonia, nitrate, acidity, metals, and sulfate. Concentrations of metals in vadose water samples (<5-m depth) from sludge-treated spoil (pH 5.9) were not elevated relative to untreated spoil (pH 4.4). In contrast, concentrations of nitrate were elevated in vadose water samples from sludge-treated spoil, frequently exceeding 10 mg/L. Downgradient decreases in nitrate to less than 3 mg/L and increases in sulfate concentrations in underlying ground water could result from oxidation of pyrite by nitrate. Thus, sewage sludge added to pyritic spoil can increase the growth of iron-oxidizing bacteria, the oxidation of pyrite, and the acidification of ground water. Nevertheless, the overall effects on ground water chemistry from the sludge were small and probably short-lived relative to the effects from mining only.

Distribution of polychlorinated biphenyls in the Housatonic River and adjacent aquifer, Massachusetts

USGS Publications Warehouse

Gay, Frederick B.; Frimpter, Michael H.

1985-01-01

Polychlorinated biphenyls (PCB's) are sorbed to the fine-grained stream-bottom sediments along the Housatonic River from Pittsfield, Massachusetts, southward to the Massachusetts-Connecticut boundary. The highest PCB concentrations, up to 140,000 micrograms per kilogram, were found in samples of bottom material from a reach of the river between Pittsfield and Woods Pond Dam in Lee, Massachusetts. Sediments in Woods Pond have been estimated to contain about 11,000 pounds of PCB's. Approximately 490 pounds per year of PCB's have also been estimated to move past the Housatonic River gaging station at Great Barrington. The distribution of hydraulic heads, water temperatures, and concentrations of dissolved oxygen, ammonia, nitrate, iron, and manganese in ground water shows that industrial water-supply wells in a sand and gravel aquifer adjacent to a stretch of the river called Woods Pond have been inducing ground-water recharge through the PCB-contaminated bottom sediments of the pond since late 1956. These data indicate that, at one location along the shore of the pond, the upper 40 feet of the aquifer contains water derived from induced infiltration. However, this induced recharge has not moved PCB's from the bottom sediments into a vertical section of the aquifer located 5 feet downgradient from the edge of Woods Pond. Samples taken at selected intervals in this section showed that no PCB's sorbed to the aquifer material or dissolved in the ground water within the detection limits of the chemical analyses.

Superfund Record of Decision (EPA Region 2): Garden State Cleaners, Buena Borough, Atlantic County, NJ. (First remedial action), September 1991. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-09-26

The 3,000-square-foot Garden State Cleaners (GSC) site is an active dry cleaning operation in Minotola, Bueno Borough, Atlantic County, New Jersey. Land use in the area is residential and commercial, and local residents obtain drinking water from the Borough municipal water supply system. From 1966 to the present, dry cleaning activities using PCE were conducted at the GSC site, and until 1985, wastes were discharged through pipes directly into the ground. In 1984, State investigations showed elevated levels of PCE in ground water adjacent to and downgradient from the GSC and SJCC facilities, and elevated levels of PCE and TCEmore » in onsite soil. The selected remedial action for the site includes treating onsite approximately 1,600 cubic yards of contaminated soil using in-situ vapor extraction; treating the contaminated wastewater from the vapor extraction processes onsite using an air stripping column; treating air emissions using carbon adsorption units; pumping and onsite treatment of contaminated ground water using air stripping and carbon adsorption; reinjecting the treated ground water upgradient from the site; regenerating spent activated carbon from both treatment processes offsite; conducting long-term ground water monitoring; and implementing temporary institutional controls. The estimated present worth cost for the remedial action at the GSC site is $5,451,000, which includes an estimated annual O and M cost of $249,500 for 70 years.« less

Groundwater flow, quality (2007-10), and mixing in the Wind Cave National Park area, South Dakota

USGS Publications Warehouse

Long, Andrew J.; Ohms, Marc J.; McKaskey, Jonathan D.R.G.

2012-01-01

A study of groundwater flow, quality, and mixing in relation to Wind Cave National Park in western South Dakota was conducted during 2007-11 by the U.S. Geological Survey in cooperation with the National Park Service because of water-quality concerns and to determine possible sources of groundwater contamination in the Wind Cave National Park area. A large area surrounding Wind Cave National Park was included in this study because to understand groundwater in the park, a general understanding of groundwater in the surrounding southern Black Hills is necessary. Three aquifers are of particular importance for this purpose: the Minnelusa, Madison, and Precambrian aquifers. Multivariate methods applied to hydrochemical data, consisting of principal component analysis (PCA), cluster analysis, and an end-member mixing model, were applied to characterize groundwater flow and mixing. This provided a way to assess characteristics important for groundwater quality, including the differentiation of hydrogeologic domains within the study area, sources of groundwater to these domains, and groundwater mixing within these domains. Groundwater and surface-water samples collected for this study were analyzed for common ions (calcium, magnesium, sodium, bicarbonate, chloride, silica, and sulfate), arsenic, stable isotopes of oxygen and hydrogen, specific conductance, and pH. These 12 variables were used in all multivariate methods. A total of 100 samples were collected from 60 sites from 2007 to 2010 and included stream sinks, cave drip, cave water bodies, springs, and wells. In previous approaches that combined PCA with end-member mixing, extreme-value samples identified by PCA typically were assumed to represent end members. In this study, end members were not assumed to have been sampled but rather were estimated and constrained by prior hydrologic knowledge. Also, the end-member mixing model was quantified in relation to hydrogeologic domains, which focuses model results on major hydrologic processes. Finally, conservative tracers were weighted preferentially in model calibration, which distributed model errors of optimized values, or residuals, more appropriately than would otherwise be the case The latter item also provides an estimate of the relative effect of geochemical evolution along flow paths in comparison to mixing. The end-member mixing model estimated that Wind Cave sites received 38 percent of their groundwater inflow from local surface recharge, 34 percent from the upgradient Precambrian aquifer, 26 percent from surface recharge to the west, and 2 percent from regional flow. Artesian springs primarily received water from end members assumed to represent regional groundwater flow. Groundwater samples were collected and analyzed for chlorofluorocarbons, dissolved gasses (argon, carbon dioxide, methane, nitrogen, and oxygen), and tritium at selected sites and used to estimate groundwater age. Apparent ages, or model ages, for the Madison aquifer in the study area indicate that groundwater closest to surface recharge areas is youngest, with increasing age in a downgradient direction toward deeper parts of the aquifer. Arsenic concentrations in samples collected for this study ranged from 0.28 to 37.1 micrograms per liter (μg/L) with a median value of 6.4 μg/L, and 32 percent of these exceeded 10 μg/L. The highest arsenic concentrations in and near the study area are approximately coincident with the outcrop of the Minnelusa Formation and likely originated from arsenic in shale layers in this formation. Sample concentrations of nitrate plus nitrite were less than 2 milligrams per liter for 92 percent of samples collected, which is not a concern for drinking-water quality. Water samples were collected in the park and analyzed for five trace metals (chromium, copper, lithium, vanadium, and zinc), the concentrations of which did not correlate with arsenic. Dye tracing indicated hydraulic connection between three water bodies in Wind Cave.

Bioremediation of a Large Chlorinated Solvent Plume, Dover AFB, DE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bloom, Aleisa C

2015-01-01

Bioremediation of a Large Chlorinated Solvent Plume, Dover AFB, DE Aleisa Bloom, (Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA) Robert Lyon (bob.lyon@aecom.com), Laurie Stenberg, and Holly Brown (AECOM, Germantown, Maryland, USA) ABSTRACT: Past disposal practices at Dover Air Force Base (AFB), Delaware, created a large solvent plume called Area 6 (about 1 mile long, 2,000 feet wide, and 345 acres). The main contaminants are PCE, TCE, and their degradation products. The remedy is in-situ accelerated anaerobic bioremediation (AAB). AAB started in 2006 and is focusing on source areas and downgradient plume cores. Direct-push injections occurred in source areas wheremore » contamination is typically between 5 and 20 feet below ground surface. Lower concentration dissolved-phased contamination is present downgradient at 35 and 50 feet below ground surface. Here, permanent injection/extraction wells installed in transects perpendicular to the flow of groundwater are used to apply AAB. The AAB substrate is a mix of sodium lactate, emulsified vegetable oil, and nutrients. After eight years, dissolved contaminant mass within the main 80-acre treatment area has been reduced by over 98 percent. This successful application of AAB has stopped the flux of contaminants to the more distal portions of the plume. While more time is needed for effects to be seen in the distal plume, AAB injections will soon cease, and the remedy will transition to natural attenuation. INTRODUCTION Oak Ridge National Laboratory Environmental Science Division (ORNL) and AECOM (formerly URS Corporation) have successfully implemented in situ accelerated anaerobic bioremediation (AAB) to remediate chlorinated solvent contamination in a large, multi-sourced groundwater plume at Dover Air Force Base (AFB). AAB has resulted in significant reductions of dissolved phase chlorinated solvent concentrations. This plume, called Area 6, was originally over 1 mile in length and over 2,000 feet wide (Figure 1). It originated from at least four separate source areas that comingled in the subsurface to form the large plume. The major contaminants of concern (COCs) are tetrachloroethene (PCE), trichloroethene (TCE), and 1,1,1-trichloroethane (1,1,1-TCA), which were historically used for degreasing operations in the maintenance of aircraft and support vehicles. Relatively small areas of elevated PCE, TCE, and 1,1,1-TCA were delineated in the shallow portion of the water table aquifer by direct-push groundwater sampling. Focused direct-push AAB treatment occurred in March 2006 at these source areas (Figure 1). Downgradient of the these areas and deeper in the aquifer, AAB treatment was implemented using rows of extraction/injection wells oriented perpendicular to groundwater flow to create multiple reductive zones across the plume cores, defined as areas where more than 1,000 micrograms per liter (ug/L) total solvent concentrations were present. Initial indications of successful degradation were observed within 6 months of starting injections. FIGURE 1. Dover AFB Area 6 plume. This paper describes the AAB implementation and progress of remediation after 8 years of treatment and periodic groundwater monitoring. SITE LITHOLOGY Contamination at the site is limited to the surficial aquifer, which consists of 35 to 50 feet (ft) (11 to 15 meters [m]) of unconsolidated Pleistocene deposits of the Columbia Formation. The Columbia Formation consists of fine to coarse sand with silt and clay lenses and less common gravel lenses. Silts and silty sands are generally encountered to a depth of 10 to 12 ft (3.05 to 3.65 m) below ground surface (bgs) and grade to medium- and coarse-grained sands to a depth of 35 to 50 ft (11 to 15 m) bgs. There is a clay and silt unit (part of the Calvert Formation) below the surficial aquifer that acts as an aquitard to the downward migration of contaminants. The depth to the water table varies across the site but usually ranges from 8 to 15 ft (2.4 to 4.5 m) bgs in the treatment area. REMEDIAL APPROACH AND OPERATIONS Because the Columbia Aquifer is used as a source of potable water off base, the remedial goal is to restore the aquifer to usable condition, i.e., reduce all chemicals of concern to below drinking water maximum contaminant levels (MCLs). To achieve this goal, AAB was selected as the best remedial alternative to reduce the solvent contamination. Source areas with high solvent concentrations were present in the shallow portion of the aquifer. From the source areas, dissolved solvents migrated downgradient and deeper in the aquifer with the flow of groundwater. In the deeper portion of the aquifer, the individual plumes comingle to form the larger Area 6 Plume, which covers approximately 345 acres. Types of Substrate. Previous AAB pilot tests at Dover AFB used either sodium lactate or emulsified vegetable oil (EVO) as substrates to stimulate microbial growth. The best results were obtained with...« less

Hydrogeologic reconnaissance of the Swope Oil Superfund site and vicinity, Camden and Burlington counties, New Jersey

USGS Publications Warehouse

Barton, G.J.; Krebs, M.M.

1990-01-01

Groundwater beneath a former chemical reclamation facility in New Jersey is contaminated with metals and organic compounds. The off-site migration of these compounds has not been studied; however, a nearby public-supply well is contaminated, and a public-supply well 1,400 ft downgradient from the site may be threatened. The study area, in the New Jersey part of the Atlantic Coastal Plain, is underlain by alluvial deposits composed of gravel, sand, silt, and clay. These deposits comprise the water table aquifer, the confining units, and the confined aquifer throughout the study area. The water table beneath the Swope Oil Superfund site is approximately 17 ft below sea level and groundwater levels throughout the study area are below the stage of the Delaware River. The aquifer system is recharged by precipitation, leakage of water through confining units, and the water induced from the Delaware River. Five public supply-well fields, primarily adjacent to the Delaware River, and four waste disposal sites with observation well networks are located in the study area. Both the water table and confined aquifers are contaminated in several locations. The concentration of metals and/or purgeable organic compounds in more than 20 wells exceeds the U.S. Environmental Protection Agency primary drinking-water standard and the New Jersey Department of Environmental Protection recommended drinking water criteria. Selected data from wells and test borings are presented, including well construction details; drillers ', geologists ', and geophysical logs; water levels; specific-capacity and slug test data; and chemical analysis of groundwater samples. (USGS)

Geographically Isolated Wetlands are Part of the Hydrological Landscape

EPA Science Inventory

A recent report by the U.S. Environmental Protection Agency concluded that all wetlands located on floodplains and/or within riparian areas have significant chemical, physical, and/or biological connections with downgradient WOUS. The report concludes that other wetlands – includ...

Element concentrations in growth rings of trees near an abandoned wood-preserving plant site at Jackson, Tennessee

USGS Publications Warehouse

Yanosky, T.M.; Carmichael, J.K.

1993-01-01

Multielement analysis was performed on individual annual rings of trees growing at and near an abandoned wood-preserving plant site in Jackson, Tennessee, that operated from the early 1930's until 1981. Numerous organic compounds associated with the wood-preserving process have been detected in soils, ground water, and surface water within much of the site. Tree-ring investigations were conducted prior to investigations of ground water downgradient from the site to determine if trees preserved an areal and temporal record of contaminant movement into offsite areas. Increment cores were collected from trees on the abandoned plant site, in downgradient areas west and south of the site, and at two locations presumably unaffected by contamination from the site. Multielement analysis by proton-induced X-ray emission was performed on 5 to 15 individual growth rings from each of 34 trees that ranged in age from about 5 to 50 years. Concentrations of 16 elements were evaluated by analyzing average concentrations within the 1987, 1989, and 1990 rings of all trees; analyzing element-concentration trends along entire core radii; and analyzing element correlations between and among trees. Concentrations of some nutrients and trace metals were elevated in the outermost sapwood rings of some trees that grow south and southwest of the most contaminated part of the site; small trees on the main part of the site and larger trees to the west generally contained fewer rings with elevated concentrations, particularly of trace metals. Concentrations of several elements elevated in tree rings also were elevated in water samples collected from the reach of a stream that flows near the southwestern part of the site. Multielement analysis of each ring of a willow growing along the southern boundary of the site detected extremely large concentrations of chromium, nickel, and iron in rings that formed in 1986 and thereafter. Relative increases in the concentrations of these elements also were detected in a silver maple growing next to the willow, but not in another silver maple growing 150 meters farther to the west. An oak growing in the southwestern part of the study area contained large concentrations of calcium and several trace elements, and some trees south of the abandoned site contained large concentrations of phosphorus or potassium. Concentrations of trace metals and nutrients in some trees may be related to wood-preserving activities at the site and possibly to remedial efforts conducted during the early to mid 1980's.However, the possibility cannot be discounted that large concentrations of some elements are from sources other than the wood-preserving facility, or in part from flooding of the South Fork Forked Deer River.

Bounding Analysis of Drinking Water Health Risks from a Spill of Hydraulic Fracturing Flowback Water.

PubMed

Rish, William R; Pfau, Edward J

2018-04-01

A bounding risk assessment is presented that evaluates possible human health risk from a hypothetical scenario involving a 10,000-gallon release of flowback water from horizontal fracturing of Marcellus Shale. The water is assumed to be spilled on the ground, infiltrates into groundwater that is a source of drinking water, and an adult and child located downgradient drink the groundwater. Key uncertainties in estimating risk are given explicit quantitative treatment using Monte Carlo analysis. Chemicals that contribute significantly to estimated health risks are identified, as are key uncertainties and variables to which risk estimates are sensitive. The results show that hypothetical exposure via drinking water impacted by chemicals in Marcellus Shale flowback water, assumed to be spilled onto the ground surface, results in predicted bounds between 10 -10 and 10 -6 (for both adult and child receptors) for excess lifetime cancer risk. Cumulative hazard indices (HI CUMULATIVE ) resulting from these hypothetical exposures have predicted bounds (5th to 95th percentile) between 0.02 and 35 for assumed adult receptors and 0.1 and 146 for assumed child receptors. Predicted health risks are dominated by noncancer endpoints related to ingestion of barium and lithium in impacted groundwater. Hazard indices above unity are largely related to exposure to lithium. Salinity taste thresholds are likely to be exceeded before drinking water exposures result in adverse health effects. The findings provide focus for policy discussions concerning flowback water risk management. They also indicate ways to improve the ability to estimate health risks from drinking water impacted by a flowback water spill (i.e., reducing uncertainty). © 2017 Society for Risk Analysis.

Changes in organic matter biodegradatility influencing sulfate reduction in an aquifer contaminated by landfill leachate

USGS Publications Warehouse

Harris, Steve H.; Istok, Jonathan D.; Suflita, Joseph M.

2006-01-01

In situ experiments were conducted to measure sulfate reduction rates and identify rate-limiting factors in a shallow, alluvial aquifer contaminated with municipal landfill leachate. Single-well, push–pull tests conducted in a well adjacent to the landfill with >8 mM dissolved organic carbon (DOC) exhibited a sulfate reduction rate of 3.2 μmol SO4−2 (L sediment)−1 day−1, a value in close agreement with laboratory-derived estimates. Identical tests conducted in wells located 90 m downgradient where DOC levels remained high (>3 mM) showed no detectable sulfate consumption, and laboratory assays confirmed this observation. However, the rates of sulfate reduction in sediment samples obtained from this site were three times larger when they were amended with filter-sterilized groundwater from the upgradient location. The effect of various amendments on sulfate reduction rates was further examined in laboratory incubations using sediment collected from the downgradient site amended with 35S sulfate. Unamended sediments showed only weak conversion of the tracer to 35S sulfide (5 to 7 cpm/cm2), whereas the addition of Desulfovibrio cells increased 35S sulfide production to 44 cpm/cm2. However, the application of heat-killed Desulfovibrio had a similar stimulatory effect, as did a lactate amendment. Collectively, these findings indicate that the lack of measurable sulfate reduction at the downgradient site was not due to the absence of the necessary metabolic potential, the presence of lower sulfate concentration, or the quantity of electron donor, but by its biodegradability. The findings also indicate that field bioaugmentation attempts should be interpreted with caution.

Field evidence for a protistan role in an organically-contaminated aquifer

USGS Publications Warehouse

Kinner, Nancy E.; Harvey, Ronald W.; Shay, David M.; Metge, David W.; Warren, Alan

2002-01-01

The association between protists, bacteria, and dissolved organic carbon (DOC) in an oxygen-depleted, 6 km-long wastewater contaminant plume within a sandy aquifer (Cape Cod, MA) was investigated by comparing abundance patterns along longitudinal and vertical transects and at a control site. Strong linear correlations were observed between unattached bacterial abundance and DOC for much of the upgradient-half of the plume (0.1−2.5 km downgradient from the source) that is characterized by quasi-steady state chemistry. However, a logarithmic decrease was observed between the number of protists supported per mg of DOC and the estimated age of the DOC within the plume. The relatively labile dissolved organic contaminants that characterize the groundwater sampled from the plume ≤0.1 km downgradient from the contaminant source appeared to indirectly support 3−4 times as many protists (per mg of DOC) as the older, more recalcitrant DOC in the alkylbenzene sulfonate (ABS)-contaminated zone at 3 km downgradient (∼30 years travel time). Substantive numbers of protists (>104/cm3) were recovered from suboxic zones of the plume. The higher than expected ratios of protists to unattached bacteria (10 to 100:1) observed in much of the plume suggest that protists may be grazing upon both surface-associated and unattached bacterial communities to meet their nutritional requirements. In closed bottle incubation experiments, the presence of protists caused an increase in bacterial growth rate, which became more apparent at higher amendments of labile DOC (3−20 mgC/L). The presence of protists resulted in an increase in the apparent substrate saturation level for the unattached bacterial community, suggesting an important role for protists in the fate of more-labile aquifer organic contaminants.

Public health assessment for El Toro Marine Corps Air Station, Santa Ana, Orange County, California, Region 9. CERCLIS No. CA6170023208. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

El Toro Marine Corps Air Station is in Orange County, California, near the city of Irvine. The Marine Corps established El Toro in 1943, and it currently serves as the center for marine aviation operations on the Pacific Coast. El Toro Marine Corps Air Station was proposed for listing on EPA's National Priorities List (NPL) in 1989 because past operations and disposal practices contaminated local groundwater. Agricultural farm workers and well operators are exposed to contaminants in groundwater through unintentional ingestion of contaminated groundwater, dermal contact with contaminated groundwater, and inhalation of aerosolized groundwater contaminants. Future exposure could occur throughmore » two potable water wells that are located 10 miles downgradient of the contaminant plume. At the current rate of contaminant migration, those wells will be affected in one and a half to five years.« less

Potential Aquifer Vulnerability in Regions Down-Gradient from Uranium In Situ Recovery (ISR) Sites

EPA Science Inventory

Sandstone-hosted roll-front uranium ore deposits originate when U(VI) dissolved in groundwater is reduced and precipitated as insoluble U(IV) minerals. Groundwater redox geochemistry, aqueous complexation, and solute migration are instrumental in leaching uranium from source rock...

40 CFR 257.25 - Assessment monitoring program.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Minimum distance between upgradient edge of the unit and downgradient monitoring well screen (minimum... that is likely to be without appreciable risk of deleterious effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or...

40 CFR 257.25 - Assessment monitoring program.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Minimum distance between upgradient edge of the unit and downgradient monitoring well screen (minimum... that is likely to be without appreciable risk of deleterious effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or...

40 CFR 257.25 - Assessment monitoring program.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Minimum distance between upgradient edge of the unit and downgradient monitoring well screen (minimum... that is likely to be without appreciable risk of deleterious effects during a lifetime. For purposes of this subpart, systemic toxicants include toxic chemicals that cause effects other than cancer or...

Denitrification and mixing in a stream-aquifer system: Effects on nitrate loading to surface water

USGS Publications Warehouse

McMahon, P.B.; Böhlke, J.K.

1996-01-01

Ground water in terrace deposits of the South Platte River alluvial aquifer near Greeley, Colorado, USA, had a median nitrate concentration of 1857 ??mol l-1. Median nitrate concentrations in ground water from adjacent floodplain deposits (468 ??mol l-1) and riverbed sediments (461 ??mol l-1), both of which are downgradient from the terrace deposits, were lower than the median concentration in the terrace deposits. The concentrations and ??15N values of nitrate and N2 in ground water indicated that denitrifying activity in the floodplain deposits and riverbed sediments accounted for 15- 30% of the difference in nitrate concentrations. Concentrations of Cl- and SiO2 indicated that mixing between river water and ground water in the floodplain deposits and riverbed sediments accounted for the remainder of the difference in nitrate concentrations. River flux measurements indicated that ground-water discharge in a 7.5 km segment of river had a nitrate load of 1718 kg N day-1 and accounted for about 18% of the total nitrate load in the river at the downstream end of that segment. This nitrate load was 70% less than the load predicted on the basis of the median nitrate concentration in the terrace deposits and assuming no denitrification or mixing in the aquifer. Water exchange between the river and aquifer caused ground water that originally discharged to the river to reenter denitrifying sediments in the riverbed and floodplain, thereby further decreasing the nitrate load in this stream-aquifer system. Results from this study indicated that denitrification and mixing within alluvial aquifer sediments may substantially decrease the nitrate load added to rivers by discharging ground water.

Consequences of Groundwater Development on Water Resources of Hawai`i

NASA Astrophysics Data System (ADS)

Rotzoll, K.; Izuka, S. K.; El-Kadi, A. I.

2017-12-01

The availability of fresh groundwater for human use is limited by whether the impacts of withdrawals are deemed acceptable by community stakeholders and water-resource managers. Quantifying the island-wide hydrologic impacts of withdrawal—saltwater intrusion, water-table decline, and reduction of groundwater discharge to streams, nearshore environments and downgradient groundwater bodies—is thus a key step for assessing fresh groundwater availability in Hawai`i. Groundwater-flow models of the individual islands of Kaua`i, O`ahu, and Maui were constructed using MODFLOW 2005 with the Seawater-Intrusion Package (SWI2). Consistent model construction among the islands, calibration, and analysis were streamlined using Python scripts. Results of simulating historical withdrawals from Hawai`i's volcanic aquifers show that the types and magnitudes of impacts that can limit fresh groundwater availability vary among each islands' unique hydrogeologic settings. In high-permeability freshwater-lens aquifers, saltwater intrusion and reductions in coastal groundwater discharge are the principal consequences of withdrawals that can limit groundwater availability. In dike-impounded groundwater and thickly saturated low-permeability aquifers, reduced groundwater discharge to streams, water-table decline, or reduced flows to adjacent freshwater-lens aquifers can limit fresh groundwater availability. The numerical models are used to quantify and delineate the spatial distribution of these impacts for the three islands. The models were also used to examine how anticipated changes in groundwater recharge and withdrawals will affect fresh groundwater availability in the future.

Water resources of the Keweenaw Bay Indian Community, Baraga County, Michigan

USGS Publications Warehouse

Sweat, M.J.; Rheaume, S.J.

1998-01-01

The Keweenaw Bay Indian Community (KBIC) in Baraga County uses ground water for most domestic, commercial, and industrial supplies. An industrial park within KBIC could adversely affect some ground-water supplies should contaminants be spilled at the park. Additional development of the park is being planned. Information on water supply potential and aquifer vulnerability to contamination is needed to make sound decisions about future activities at the industrial park. Unconsolidated glacial deposits overlie bedrock within the Keweenaw Bay Indian Community. Usable amounts of ground water are withdrawn from the glacial deposits only in isolated areas. Principal aquifers are the Jacobsville Sandstone and the Michigamme Slate. Aquifer test and water level data from these principal aquifers indicate that they are confined and hydraulically connected throughout most of KBIC. Ground water generally flows toward Keweenaw and Huron Bays and the Silver River. Between the industrial park and Keweenaw Bay, ground water flows to the southeast, toward the Bay. Along this flow path in the bedrock, glacial deposits are generally thicker than 25 meters, and contain thick lenses of clay and clay mixed with sand. The average depth to ground water along this flow path is greater than 25 meters, indicating unconfined conditions. Near the shore of Keweenaw and Huron Bays, however, and at isolated areas throughout KBIC, water levels in wells are above land surface. Analyses of water samples collected in 1991 and 1997 indicate that the quality of ground water and surface water is suitable for most domestic, commercial, and industrial uses. However, U.S. Environmental Protection Agency secondary maximum contaminant limits for dissolved iron and manganese were exceeded in 4 and 5 wells, respectively, which may make the water from these wells unsuitable for some uses. Concentrations of lead in water from one well was above the maximum contaminant limit. Concentrations of tritium in ground water downgradient from the industrial park indicate that at least some recharge to the Jacobsville Sandstone has taken place within the last 45 years. Where clay lenses greater than 1 meter thick overlie the glacial aquifer or the Jacobsville Sandstone, however, recharge may take longer than 45 years. A contaminant spill at the industrial park would likely move laterally, toward Keweenaw Bay, in the glacial aquifer. Some infiltration does occur through the glacial aquifer to the bedrock aquifers. No information is available concerning the rate of movement of water within this aquifer, so it is not possible to determine the rate at which a spill would move either vertically or laterally within the glacial aquifer toward either Keweenaw Bay or the Jacobsville Sandstone. Increased pumping from the existing well at the industrial park, or the development of additional wells, could potentially lower water levels in the Jacobsville Sandstone in the area of the park. Sufficient lowering of water levels could create unconfined conditions in the Jacobsville Sandstone, thereby increasing the susceptability of the aquifer to contamination.

Tracing ground-water movement by using the stable isotopes of oxygen and hydrogen, upper Penitencia Creek alluvial fan, Santa Clara Valley, California

USGS Publications Warehouse

Muir, K.S.; Coplen, Tyler B.

1981-01-01

Starting in 1965 the Santa Clara Valley Water District began importing about i00,000 acre-feet per year of northern California water. About one-half of this water was used to artificially recharge the Upper Penitencia Creek alluvial fan in Santa Clara Valley. In order to determine the relative amounts of local ground water and recharged imported water being pumped from the wells, stable isotopes of oxygen and hydrogen were used to trace the movement of the imported water in the alluvial fan. To trace the movement of imported water in the Upper Penitencia Creek alluvial fan, well samples were selected to give areal and depth coverage for the whole fan. The stable isotopes of oxygen-16, oxygen-18, and deuterium were measured in the water samples of imported water and from the wells and streams in the Santa Clara Valley. The d18oand dD compositions of the local runoff were about -6.00 o/oo (parts per thousand) and -40 o/oo, respectively; the average compositions for the local native ground-water samples were about -6.1 o/oo and -41 o/oo, respectively; and the average compositions of the imported water samples were -10.2 o/oo and -74 o/oo, respectively. (The oxygen isotopic composition of water samples is reported relative to Standard Mean Ocean Water, in parts per thousand.) The difference between local ground water and recharged imported water was about 4.1 o/oo in d18o and 33 o/oo in dL. The isotopic data indicate dilution of northern California water with local ground water in a downgradient direction. Two wells contain approximately 74 percent northern California water, six wells more than 50 percent. Data indicate that there may be a correlation between the percentage of northern California water and the depth or length of perforated intervals in wells.

Sustainable yields from large diameter wells in shallow weathered aquifers

NASA Astrophysics Data System (ADS)

Rushton, K. R.; de Silva, C. S.

2016-08-01

Large diameter wells in shallow weathered aquifers provide a valuable source of water for domestic and agricultural purposes in many locations including the Indian subcontinent. However, when used for irrigation, these wells often fail towards the end of the dry season. By considering two case studies in the dry and intermediate rainfall zones of Sri Lanka, reasons for the limited yield of these wells are identified. The first case study is concerned with a sloping catchment; a significant proportion of the precipitation during the rainy season either becomes runoff or passes down-gradient through the aquifer and is discharged at the ground surface. Furthermore, during the dry season, groundwater discharge continues. In the second case study the topography is generally flat but, even though the aquifer fills most years during the rainy season, there is often only sufficient water to irrigate about half of each farmer's holding. These investigations are based on field information and the development of conceptual and computational models. Of critical importance in assessing the long term yield of a well is the formation of a seepage face on the side of the well, with the water table a significant distance above the pumping water level. Consequently the water table may only be lowered to about half the depth of the well. The paper concludes with recommendations for the exploitation of groundwater from shallow weathered aquifers to minimise the risk of failure during the dry season.

Assessing Protection Afforded to the Microbiological Quality of Bedrock Groundwater from the Impacts of Septic Tank Effluent by Irish Glacial Till: A Field Study

NASA Astrophysics Data System (ADS)

Orr, Alison; McCarthy, Valerie; Meehan, Robert; Flynn, Raymond

2010-05-01

The rural population of Ireland relies almost exclusively on on-site treatment systems for disposal of waste water. Septic tank systems, which discharge effluent to ground, constitute the dominant means of waste water disposal. Many of the areas that employ this technology rely on private or small group groundwater supplies, often located in close proximity of septic tanks. Since many of these water supplies provide raw groundwater to consumers, septic tank effluent (STE) can pose a significant hazard to the microbiological quality of drinking water. T-tests (infiltration testing) carried out prior to tank installation aim to assess the capacity of subsoils to receive STE. Tests completed across Ireland indicate that many existing septic tank systems are located in low permeability subsoils. These subsoils are assumed to afford significant protection to the microbiological quality of groundwater in the underlying bedrock units. A two year investigation in the Lough Muckno Catchment in Co. Monaghan, investigating the impact of STE on water quality, involved carrying out T-tests at three sites where effluent discharged to a dense, silty, ‘fractured' glacial till derived from the underlying bedrock and containing clasts of low grade metamorphic Ordovician and Silurian sandstone and shale. Analysis of groundwater samples collected from 28 piezometers straddling the water table within the till, down-gradient of septic tank systems at two sites, permitted faecal indicator microorganism (FIO) levels in near-surface groundwater to be established. Associated hydraulic conductivity tests (slug tests) at all three sites permitted an evaluation of the levels of horizontal hydraulic conductivity heterogeneity present in the till. Slug test results suggest that till median hydraulic conductivities range from 1.1x10-4 cm/s to 1.1x10-5 cm/s, with variability of up to 2 orders of magnitude across each site. On the other hand no significant differences in properties existed between sites. T-test results ranged from 37.96 min/25mm to 98.26 min/25mm, suggesting hydraulic conductivities of the order of 1.1x10-3 cm/s to 4.24x10-4 cm/s. The contrast in hydraulic conductivity between T-test and slug test results may reflect slight anisotropy within the till, with water flowing vertically a little more easily than horizontally, under equivalent gradients. Despite the low hydraulic conductivities and the low hydraulic gradients observed at each site, analyses of water samples collected from up to 115 metres from septic tank discharge points consistently detected FIOs. The results of the study highlight the possibility of viable pathogenic microorganisms being transported considerable distances from septic tanks through fine-grained glacial tills. Given limited survival times of FIOs outside of their host organisms, study findings suggest that travel times in the till separating septic tanks from monitoring points are of the order of 10s of days, despite similarly low hydraulic conductivities determined independently by the T-test and slug test methods. The microbiological results, coupled to hydraulic measurements, point to very low effective porosities in the till that may possibly relate to fracturing. Moreover, hydraulic conductivity anisotropy suggests that contaminants may flow equally easily to depth. However, the exact levels of protection provided by the till will be a function of effective porosity variation with depth; the role played by fractures remains to be investigated but could prove to be potentially significant. Overall, the results of the study suggest that the levels of protection afforded by fine-grained Irish tills to bedrock aquifers may be considerably lower than originally assumed.

Nevada National Security Site Integrated Groundwater Sampling Plan, Revision 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilborn, Bill R.; Boehlecke, Robert F.

The purpose is to provide a comprehensive, integrated approach for collecting and analyzing groundwater samples to meet the needs and objectives of the DOE/EM Nevada Program’s UGTA Activity. Implementation of this Plan will provide high-quality data required by the UGTA Activity for ensuring public protection in an efficient and cost-effective manner. The Plan is designed to ensure compliance with the UGTA Quality Assurance Plan (QAP) (NNSA/NFO, 2015); Federal Facility Agreement and Consent Order (FFACO) (1996, as amended); and DOE Order 458.1, Radiation Protection of the Public and the Environment (DOE, 2013). The Plan’s scope comprises sample collection and analysis requirementsmore » relevant to assessing both the extent of groundwater contamination from underground nuclear testing and impact of testing on water quality in downgradient communities. This Plan identifies locations to be sampled by CAU and location type, sampling frequencies, sample collection methodologies, and the constituents to be analyzed. In addition, the Plan defines data collection criteria such as well purging, detection levels, and accuracy requirements/recommendations; identifies reporting and data management requirements; and provides a process to ensure coordination between NNSS groundwater sampling programs for sampling analytes of interest to UGTA. Information used in the Plan development—including the rationale for selection of wells, sampling frequency, and the analytical suite—is discussed under separate cover (N-I, 2014) and is not reproduced herein. This Plan does not address compliance for those wells involved in a permitted activity. Sampling and analysis requirements associated with these wells are described in their respective permits and are discussed in NNSS environmental reports (see Section 5.2). In addition, sampling for UGTA CAUs that are in the Closure Report (CR) stage are not included in this Plan. Sampling requirements for these CAUs are described in the CR. Frenchman Flat is currently the only UGTA CAU in the CR stage. Sampling requirements for this CAU are described in Underground Test Area (UGTA) Closure Report for Corrective Action Unit 98: Frenchman Flat Nevada National Security Site, Nevada (NNSA/NFO, 2016).« less

Concentrations of hormones, pharmaceuticals and other micropollutants in groundwater affected by septic systems in New England and New York.

PubMed

Phillips, P J; Schubert, C; Argue, D; Fisher, I; Furlong, E T; Foreman, W; Gray, J; Chalmers, A

2015-04-15

Septic-system discharges can be an important source of micropollutants (including pharmaceuticals and endocrine active compounds) to adjacent groundwater and surface water systems. Groundwater samples were collected from well networks tapping glacial till in New England (NE) and sandy surficial aquifer New York (NY) during one sampling round in 2011. The NE network assesses the effect of a single large septic system that receives discharge from an extended health care facility for the elderly. The NY network assesses the effect of many small septic systems used seasonally on a densely populated portion of Fire Island. The data collected from these two networks indicate that hydrogeologic and demographic factors affect micropollutant concentrations in these systems. The highest micropollutant concentrations from the NE network were present in samples collected from below the leach beds and in a well downgradient of the leach beds. Total concentrations for personal care/domestic use compounds, pharmaceutical compounds and plasticizer compounds generally ranged from 1 to over 20 μg/L in the NE network samples. High tris(2-butoxyethyl phosphate) plasticizer concentrations in wells beneath and downgradient of the leach beds (>20 μg/L) may reflect the presence of this compound in cleaning agents at the extended health-care facility. The highest micropollutant concentrations for the NY network were present in the shoreline wells and reflect groundwater that is most affected by septic system discharges. One of the shoreline wells had personal care/domestic use, pharmaceutical, and plasticizer concentrations ranging from 0.4 to 5.7 μg/L. Estradiol equivalency quotient concentrations were also highest in a shoreline well sample (3.1 ng/L). Most micropollutant concentrations increase with increasing specific conductance and total nitrogen concentrations for shoreline well samples. These findings suggest that septic systems serving institutional settings and densely populated areas in coastal settings may be locally important sources of micropollutants to adjacent aquifer and marine systems. Published by Elsevier B.V.

An assessment of natural biotransformation of petroleum hydrocarbons and chlorinated solvents at an aquifer plume transect

NASA Astrophysics Data System (ADS)

Skubal, Karen L.; Barcelona, Michael J.; Adriaens, Peter

2001-05-01

Field biogeochemical characterization and laboratory microcosm studies were performed to assess the potential for future biotransformation of trichloroethylene (TCE) and toluene in a plume containing petroleum hydrocarbons and chlorinated solvents at the former Wurtsmith Air Force Base in Oscoda, MI. In situ terminal electron accepting processes (TEAPs), contaminant composition and microbial phylogeny were studied at a plume transect 100 m downgradient of the source. The presence of reduced electron acceptors, relevant microbial communities, and elevated dissolved methane and carbon dioxide concentrations at the transect, as well as downgradient accumulation of BTEX metabolites and dechlorination products, indicated that past or current reductive dechlorination at the transect was likely driven by BTEX biodegradation in the methanogenic zone. However, TCE and toluene mineralization in sediment-groundwater microcosms without added electron acceptors did not exceed 5% during 300 days of incubation and was nearly invariant with original sediment TEAP, even following amendments of nitrogen and phosphorus. Mineralization rates were on the order of 0.0015-0.03 μmol/g day. After 8 months, microcosms showed evidence of methanogenesis, but CH 4 and CO 2 production arose from the degradation of contaminants other than toluene. Cis-dichloroethylene was observed in only one methanogenic microcosm after more than 500 days. It appears likely that spatially and temporally dynamic redox zonation at the plume transect will prevent future sustained reductive dehalogenation of highly chlorinated solvents, for during the course of a year, the predominant TEAP at the highly contaminated water table shifted from methanogenesis to iron- and sulfate-reduction. It is recommended that biotransformation studies combine considerations of long-term, spatially relevant changes in redox zonation with laboratory-scale studies of electron donor utilization and cometabolic substrate transformation to yield a more accurate assessment of natural bioattenuation of specific pollutants in aquifers contaminated by undefined organic waste mixtures.

Ammonium transport and reaction in contaminated groundwater: Application of isotope tracers and isotope fractionation studies

USGS Publications Warehouse

Böhlke, J.K.; Smith, Richard L.; Miller, Daniel N.

2006-01-01

Ammonium (NH4+) is a major constituent of many contaminated groundwaters, but its movement through aquifers is complex and poorly documented. In this study, processes affecting NH4+ movement in a treated wastewater plume were studied by a combination of techniques including large‐scale monitoring of NH4+ distribution; isotopic analyses of coexisting aqueous NH4+, NO3−, N2, and sorbed NH4+; and in situ natural gradient 15NH4+tracer tests with numerical simulations of 15NH4+, 15NO3−, and 15N2 breakthrough data. Combined results indicate that the main mass of NH4+ was moving downgradient at a rate about 0.25 times the groundwater velocity. Retardation factors and groundwater ages indicate that much of the NH4+ in the plume was recharged early in the history of the wastewater disposal. NO3− and excess N2 gas, which were related to each other by denitrification near the plume source, were moving downgradient more rapidly and were largely unrelated to coexisting NH4+. The δ15N data indicate areas of the plume affected by nitrification (substantial isotope fractionation) and sorption (no isotope fractionation). There was no conclusive evidence for NH4+‐consuming reactions (nitrification or anammox) in the anoxic core of the plume. Nitrification occurred along the upper boundary of the plume but was limited by a low rate of transverse dispersive mixing of wastewater NH4+ and O2 from overlying uncontaminated groundwater. Without induced vertical mixing or displacement of plume water with oxic groundwater from upgradient sources, the main mass of NH4+ could reach a discharge area without substantial reaction long after the more mobile wastewater constituents are gone. Multiple approaches including in situ isotopic tracers and fractionation studies provided critical information about processes affecting NH4+ movement and N speciation.

Simulating Bioremediation of Chloroethenes in a Fractured Rock Aquifer.

NASA Astrophysics Data System (ADS)

Curtis, G. P.

2016-12-01

Reactive transport simulations are being conducted to synthesize the results of a field experiment on the enhanced bioremediation of chloroethenes in a heterogeneous fractured-rock aquifer near West Trenton, NJ. The aquifer consists of a sequence of dipping mudstone beds, with water-conducting bedding-plane fractures separated by low-permeability rock where transport is diffusion-limited. The enhanced bioremediation experiment was conducted by injecting emulsified vegetable oil as an electron donor (EOS™) and a microbial consortium (KB1™) that contained dehalococcoides ethenogenes into a fracture zone that had maximum trichloroethene (TCE) concentrations of 84µM. TCE was significantly biodegraded to dichloroethene, chloroethene and ethene or CO2 at the injection well and at a downgradient well. The results also show the concomitant reduction of Fe(III) and S(6) and the production of methane . The results were used to calibrate transport models for quantifying the dominant mass-removal mechanisms. A nonreactive transport model was developed to simulate advection, dispersion and matrix diffusion of bromide and deuterium tracers present in the injection solution. This calibrated model matched tracer concentrations at the injection well and a downgradient observation well and demonstrated that matrix diffusion was a dominant control on tracer transport. A reactive transport model was developed to extend the nonreactive transport model to simulate the microbially mediated sequential dechlorination reactions, reduction of Fe(III) and S(6), and methanogenesis. The reactive transport model was calibrated to concentrations of chloride, chloroethenes, pH, alkalinity, redox-sensitive species and major ions, to estimate key biogeochemical kinetic parameters. The simulation results generally match the diverse set of observations at the injection and observation wells throughout the three year experiment. In addition, the observations and model simulations indicate that a significant pool of TCE that was initially sorbed to either the fracture surfaces or in the matrix was degraded during the field experiment. The calibrated reactive transport model will be used to quantify the extent of chloroethene mass removal from a range of hypothetical aquifers.

Investigation of the fate of sulfonamides downgradient of a decommissioned sewage farm near Berlin, Germany

NASA Astrophysics Data System (ADS)

Richter, Doreen; Massmann, Gudrun; Taute, Thomas; Duennbier, Uwe

2009-05-01

The drinking water production of a drinking water treatment plant in Berlin is affected by ambient contaminated groundwater. The three organic compounds para-toluenesulfonamide (p-TSA), ortho-toluenesulfonamide (o-TSA) and benzenesulfonamide (BSA) were identified in the catchment area of this plant. The groundwater pollution is a result of former sewage farm irrigation in the area, operating for almost 70 years until the 1980s. The distribution of the sulfonamides in the anoxic groundwater was investigated, and a large number of observation and production wells were sampled for this purpose. The contaminant plume is 25 m * 3000 m * 2000 m (depth, length, width) in size. The high concentrations of p-TSA, o-TSA and BSA in the groundwater show that the sulfonamides persist over decades in an anoxic aquifer environment. Groundwater quality assessment revealed that elevated concentrations of the analytes can be expected in the abstraction well galleries in the future. Therefore, sulfonamides should periodically be monitored in the drinking water (maximum allowed concentration of 0.30 µg/L of p-TSA and for o-TSA and BSA, a limit of 0.10 µg/L for unknown substances applies). Because of the widespread application and the persistence of the sulfonamides under anoxic conditions, our local investigations suggest that the substances may generally be present in groundwater under the influence of sewage irrigation. Incubation experiments were conducted under in situ hydrostatic pressure to study the behaviour of these trace organic compounds under different redox conditions (oxic and anoxic). Groundwater sampling equipment was either sterilised or not sterilised in order to distinguish between microbiological processes occurring in the aquifer and those representing sampling and storage artefacts (incubation experiments). Results showed that the addition of oxygen to the anoxic groundwater facilitates p-TSA and o-TSA degradation. Hence, while the substances are persistent under anoxic conditions, they are more degradable in the presence of oxygen. Results also illustrate that maintaining anoxic conditions or applying appropriate preservation techniques is necessary to ensure accurate analysis.

Testing wetland axioms at a watershed scale: Case studies of the aggregate hydrologic effects of non-adjacent wetlands

EPA Science Inventory

Wetlands not adjacent to streams (i.e. “non-adjacent wetlands”) are hypothesized to affect downgradient hydrology in a number of ways. Non-adjacent wetlands may, for example, attenuate peak flows, serve as focal points for groundwater recharge, and decrease streamflow...

A SCREENING MODEL FOR SIMULATING DNAPL FLOW AND TRANSPORT IN POROUS MEDIA: THEORETICAL DEVELOPMENT

EPA Science Inventory

There exists a need for a simple tool that will allow us to analyze a DNAPL contamination scenario from free-product release to transport of soluble constituents to downgradient receptor wells. The objective of this manuscript is to present the conceptual model and formulate the ...

Groundwater quality and its suitability for drinking and agricultural use in the Yanqi Basin of Xinjiang Province, Northwest China.

PubMed

Wang, Shuixian

2013-09-01

The Yanqi Basin in Xinjiang Province is an important agricultural area with a high population density. The extensive agricultural activities in the Yanqi Basin started in the 1950s with flood irrigation techniques. Since then, the groundwater table was raised because of the absence of an efficient drainage system. This obstacle is a crucial factor that restricts sustainable socioeconomic development. Hydrochemical investigations were conducted in the Yanqi Basin, Northwestern China, to determine the chemical composition of groundwater. Sixty groundwater samples were collected from different wells to monitor the water chemistry of various ions. The results of the chemical analysis indicate that the groundwater in the area is generally neutral to slightly alkaline and predominantly contains Na(+) and Ca(2+) cations as well as HCO3(-) and SO4 (2+) anions. High positive correlations between HCO3 (-)-Mg(2+) + Ca(2+), SO 4 (2-)-Mg(2+), SO4 (2-)-Na(+) + K(+), and Cl(-)-Na(+) + K(+) were obtained. The total dissolved solids (TDS) mainly depend on the concentration of major ions such as HCO3(-), SO4 (2-), Cl(-), Ca(2+), Mg(2+), and Na(+) + K(+). The dominant hydrochemical facies for groundwater are Ca(2+)-Mg(2+)-HCO3(-), Mg(2+)-Ca(2+)-SO4 (2-)-Cl(-), Na(+)-K(+)-Cl(-)-SO4 (2-), and Na(+)-K(+)-Mg(2+)-Cl(-)-HCO3(-) types. The hydrochemical processes are the main factors that determine the water quality of the groundwater system. These processes include silicate mineral weathering, dissolution, ion exchange, and, to a lesser extent, evaporation, which seem to be more pronounced downgradient of the flow system. The saturation index (SI), which is calculated according to the ionic ratio plot, indicates that the gypsum-halite dissolution reactions occur during a certain degree of rock weathering. SI also indicates that evaporation is the dominant factor that determines the major ionic composition in the study area. The assessment results of the water samples using various methods indicate that the groundwater in the study area is generally hard, fresh to brackish, high to very high saline, and low alkaline in nature. The high total hardness and TDS of the groundwater in several places indicate the unsuitability of the groundwater for drinking and irrigation. These areas require particular attention, particularly in the construction of adequate drainage as well as in the introduction of an alternative salt tolerance cropping.

Natural iodine-129 as an environmental tracer

NASA Astrophysics Data System (ADS)

Fabryka-Martin, J.; Bentley, H.; Elmore, D.; Airey, P. L.

1985-02-01

Iodine-129 ( t 1/2, 16 My) is a naturally-occurring tracer which can be used to study hydrologic and geologic processes on time scales up to 100 My. The pre-bomb atmospheric ratio 129I /I should have been constant in time and space and is the starting value in ground-water recharge. Subsequent ratio changes in ground water should be determined by isotope contributions from three sources: recharge water, iodine leached from the formation, and in situ uranium fission. The mathematical expression of these time-dependent processes forms the basis for dating and tracing applications. The expected behavior of natural 129I in ground water is compared to results from field studies. Ground-water samples from the Great Artesian Basin, Australia, provide an estimate of the atmospheric equilibrium ratio, 6 × 10 -13. Down-gradient changes in water up to 1 My old suggest that subsurface production can be significant. The usefulness of 129I as an indicator of brine source and age is verified in brines collected in and around Louisiana salt domes. The method leads to ages of 7 and 9 My for two brine pockets trapped within Jurassic salt, and 32 to >40 My for oil-field brines in Miocene sands adjacent to the domes. The results demonstrate the capability of tandem accelerator mass spectrometry to measure as few as 10 7 atoms of 129I in 10 mg I with 10% precision. Although such atom sensitivity can be achieved otherwise, the accelerator technique is necessary to measure naturally low pre-1945 cosmogenic isotope ratios.

Environmental occurrence and shallow ground water detection of the antibiotic monensin from dairy farms

USGS Publications Warehouse

Watanabe, N.; Harter, T.H.; Bergamaschi, B.A.

2008-01-01

Pharmaceuticals used in animal feeding operations have been detected in various environmental settings. There is a growing concern about the impact on terrestrial and aquatic organisms and the development of antibiotic-resistant strains of microorganisms. Pharmaceutical use in milking cows is relatively limited compared with other livestock operations, except for the ionophore monensin, which is given to lactating cows as a feed. By weight, monensin can be the most significant antibiotic used in a dairy farm. This study investigates the potential of monensin to move from dairy operations into the surrounding ground water. Using two dairy farms in California as study sites, we twice collected samples along the environmental pathway-from flush lanes, lagoon waters, and shallow ground water beneath the dairies and beneath its associated manured fields. Monensin concentrations were determined using solid-phase extraction and liquid chromatography-tandem mass spectrometry with positive electrospray ionization. Monensin was detected in all of the flush lane and lagoon water samples. Theoretical maximum concentration estimated from the actual dosing rate and the theoretical excretion rate assuming no attenuation was one order of magnitude greater than observed concentrations, suggesting significant attenuation in the manure collection and storage system. Monensin was also detected, at levels ranging from 0.04 to 0.39 microg L(-1), in some of the ground water samples underneath the production area of the dairy but not from the adjacent manured fields. Concentrations in ground water immediately downgradient of the lagoons were one to two orders of magnitude lower than the concentrations detected in lagoons, suggesting attenuation in the subsurface. The data suggest the possibility of monensin transport into shallow (2-5 m) alluvial ground water from dairy management units, including manure storage lagoons and freestalls occupied by heifers, lactating cows, and dry cows.

Performance of deep-rooted phreatophytic trees at a site containing total petroleum hydrocarbons.

PubMed

Ferro, Ari M; Adham, Tareq; Berra, Brett; Tsao, David

2013-01-01

Poplar and willow tree stands were installed in 2003 at a site in Raleigh, North Carolina containing total petroleum hydrocarbon - contaminated groundwater. The objective was groundwater uptake and plume control. The water table was 5 to 6 m below ground surface (bgs) and therefore methods were used to encourage deep root development. Growth rates, rooting depth and sap flow were measured for trees in Plot A located in the center of the plume and in Plot B peripheral to the plume. The trees were initially sub-irrigated with vertically installed drip-lines and by 2005 had roots 4 to 5 m bgs. Water balance calculations suggested groundwater uptake. In 2007, the average sap flow was higher for Plot B (approximately 59 L per day per tree) than for Plot A (approximately 23 L per day per tree), probably as a result of TPH-induced stress in Plot A. Nevertheless, the estimated rate of groundwater uptake for Plot A was sufficient, relative to the calculated rate of groundwater flux beneath the stand, that a high level of plume control was achieved based on MODFLOW modeling results. Down-gradient groundwater monitoring wells installed in late 2011 should provide quantitative data for plume control.

1998 Environmental Monitoring Program Report for the Idaho National Engineering and Environmental Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

L. V. Street

This report describes the calendar year 1998 compliance monitoring and environmental surveillance activities of the Lockheed Martin Idaho Technologies Company Environmental Monitoring Program performed at the Idaho National Engineering and Environmental Laboratory. This report includes results of sampling performed by the Drinking Water, Effluent, Storm Water, Groundwater Monitoring, and Environmental Surveillance Programs. This report compares the 1998 results to program-specific regulatory guidelines and past data to evaluate trends. The primary purposes of the monitoring and surveillance activities are to evaluate environmental conditions, to provide and interpret data, to verify compliance with applicable regulations or standards, and to ensure protection ofmore » public health and the environment. Surveillance of environmental media did not identify any previously unknown environmental problems or trends, which would indicate a loss of control or unplanned releases from facility operations. The INEEL complied with permits and applicable regulations, with the exception of nitrogen samples in a disposal pond effluent stream and iron and total coliform bacteria in groundwater downgradient from one disposal pond. Data collected by the Environmental Monitoring Program demonstrate that the public health and environment were protected.« less

Iron in the aquifer system of Suffolk County, New York, 1990–98

USGS Publications Warehouse

Brown, Craig J.; Walter, Donald A.; Colabufo, Steven

1999-01-01

High concentrations of dissolved iron in ground water contribute to the biofouling of public-supply wells, and the treatment and remediation of biofouling are costly. Water companies on Long Island, N.Y., spend several million dollars annually to recondition, redevelop, and replace supply wells and distribution lines; treat dissolved iron with sequestering agents or by filtration; and respond to iron-related complaints by customers. This report summarizes the results of studies done by the U.S. Geological Survey, in cooperation with the Suffolk County Water Authority, to characterize the geochemistry and microbiology of iron in the aquifer system of Suffolk County. This information should be helpful for the siting and operation of supply wells.Concentrations of dissolved iron in Long Island's ground water, and the frequency of iron biofouling of wells, are highest in ground-water-discharge zones, particularly near the south shore. Ground water along a deep north-south flowpath of the Magothy aquifer in southwestern Suffolk County becomes anaerobic (oxygen deficient) and Fe(III) reducing at a distance of 8 to 10 kilometers south of the ground-water divide, and this change coincides with the downgradient increase in dissolved iron concentrations. The distribution of organic carbon, and the distribution and local variations in reactivity of Fe(III), in Magothy aquifer sediments have resulted in localized differences in redox microenvironments. For example, Fe(III)-reducing zones are associated with anaerobic conditions, where relatively large amounts of Fe(III) oxyhydroxide grain coatings are present, whereas sulfate-reducing zones are associated with lignite-rich lenses of silt and clay and appear to have developed in response to the depletion of available Fe(III) oxyhydroxides. The sulfate-reducing zones are characterized by relatively low concentrations of dissolved iron (resulting from iron-disulfide precipitation) and may be large enough to warrant water-supply development.Specific-capacity and water-quality data from wells screened in the Magothy aquifer indicate that water from biofouled wells contains higher median concentrations of total and dissolved iron and manganese, total phosphate, and dissolved sulfate, and lower median concentrations of dissolved oxygen and alkalinity, and lower pH, than does water from unaffected wells. Corresponding data from wells screened in the upper glacial aquifer indicate that water from biofouled wells contains higher median concentrations of total and dissolved manganese and dissolved sulfate, and lower pH, than does water from unaffected wells.Filamentous bacteria were detected in 31 (or 72 percent) of the 43 biofilm samples obtained from biofouled wells during reconditioning. The predominant filamentous organism was Gallionella ferruginea, a major biofouling agent in the upper glacial and Magothy aquifers throughout Suffolk County. Mineral-saturation indices indicate that most of the well-encrusting material is deposited when the wells are shut down. Furthermore, the use of treated water (which has a high pH and sometimes high concentrations of dissolved iron) for pump prelubrication when wells are shut down could greatly increase the rate of iron oxidation.

Effect of urbanization on the water resources of eastern Chester County, Pennsylvania

USGS Publications Warehouse

Sloto, R.A.

1987-01-01

The effects of human activity on the water resources of a 207-square-mile area of eastern Chester County was evaluated. The most serious consequence of urbanization is the contamination of ground water by volatile organic compounds, which were detected in 39 percent of the 70 wells sampled. As many as nine compounds were found in one water sample, and the concentration of total volatile organic compounds was as high as 17,400 ug/L (micrograms per liter). In the Chester Valley, volatile organic compounds are moving down the hydraulic gradient caused by quarry dewatering. Movement through the quarries reduces concentrations of these compounds and removes most of them. Phenol was detected in 28 percent of 54 wells sampled, with concentrations up to 7 ug/L. Metals, except for iron and manganese, and other trace constituents generally are not a water-quality problem. However, ground water in an area in Chester Valley has been contaminated by concentrations of boron as high as 20,000 ug/L and lithium as high as 13,000 ug/L. The ground water discharges to Valley Creek, where concentrations of boron are as high as 130 ug/L and lithium as high as 800 ug/L. Concentrations of chloride as high as 2,100 mg/L (milligrams per liter) were found in a well at a former highway salt storage site. Wells completed in carbonate rock downgradient from the Pennsylvania Turnpike had chloride concentrations as high as 350 mg/L. The base-neutral organic compounds bis(2-ethylhexyl) phthalate, di-n-butyl phthalate, and 1,2-dichlorobenzene, and the pesticides alachlor, aldrian, diazanon, DDD, DDT, dieldrin, methyl parathion, picloram, and 2,4-D were detected in a few water samples in low concentrations, However, these organic compounds do not present a widespread water-quality problem. Neither acid organic compounds nor polychlorinated napthalenes (PCN) were detected in ground water. The growth of public water and sewer systems has resulted in a significant interbasin transfer of water. Estimates for 1984 range from a net loss of 630 million gallons in the Valley Creek basin to a net gain of 783 million gallons in the Chester Creek basin. The quantity of wastewater discharged from treatment plants generally correlates well with the altitude of the water table and poorly with water use or precipitation, indicating substantial ground-water infiltration. Estimated ground-water infiltration to the West Goshen treatment plant for 1980-84 was 0.8 cubic feet per square mile, or 10 percent of the long-term average flow of Chester Creek. Estimated ground-water infiltration to the Valley Forge sewer system was as high as 4.9 million gallons per day. Dewatering operations at two active quarries in Chester Valley have lowered water levels locally and increased the range of the fluctuation of the local water table. The spread of the cones of depression caused by quarry pumping is limited by geologic and hydrologic controls. Pumping of high-capacity wells in Chester Valley has caused small local cones of depression and may have caused some reaches of Valley Creek or its tributaries to lose water. One of the greatest effects of human activity on the surface-water system has been the accumulation of organic compounds, particularly PCB and pesticides, on stream-bottom material. PCB, DDE, and dieldrin were found in bottom material from all eight streams sampled. Land-use changes in 10 selected subbasins were quantified and related to stream-benthic invertebrate diversity index. from 1970-80, the diversity index increased at all sites. Subbasins that had a greater change in land use had a greater increase in diversity index. The increase may be due to the banning of certain pesticides such as DDT, a decreasing use of pesticides in urbanizing subbasins, or flushing or burial of older pesticide-contaminated sediment.

Simulation of the shallow aquifer in the vicinity of Silver Lake, Washington County, Wisconsin, using analytic elements

USGS Publications Warehouse

Dunning, C.P.; Thomas, Judith Coffman; Lin, Yu-Feng

2003-01-01

A Silver Lake water budget was defined using both published hydrologic data and simulations using the calibrated model. Model simulations show that 1.08 cubic feet per second of ground water enters Silver Lake on the upgradient (primarily western) side and 0.08 cubic feet per second recharges to ground water on the downgradient (primarily eastern) side. Net precipitation (precipitation minus evaporation) on the lake is 0.04 cubic feet per second. Collectively, these water-budget terms provide a residual value of 1.04 cubic feet per second flow to Silver Creek at the north end of Silver Lake, which is a very good match to the range of measured flow (0.7 to 5.2 cubic feet per second). Ground-water recharge areas for Silver Lake are largely on the western side of the lake. The recharge area for the northern two-thirds of Silver Lake is west toward Big Cedar Lake. Assuming a porosity of 20 percent, model results indicate that the 50-year time-of-travel for recharge to Silver Lake does not extend to Big Cedar Lake. The recharge area for the southern one-third of Silver Lake is west toward Little Cedar Lake. Model results indicate that time of travel for recharge to Silver Lake from Little Cedar Lake is about 15 to 20 years. For travel times greater than 15 or 20 years, the ground-water recharge area for Little Cedar Lake and inflow from Big Cedar Lake also should be considered recharge affecting Silver Lake. Solute flux toward Silver Lake was calculated based on simulated ground-water flux and measured concentrations in the upgradient piezometers and observation wells.

Seasonal dynamics of groundwater-lake interactions at Doñana National Park, Spain

USGS Publications Warehouse

Sacks, Laura A.; Herman, Janet S.; Konikow, Leonard F.; Vela, Antonio L.

1992-01-01

The hydrologic and solute budgets of a lake can be strongly influenced by transient groundwater flow. Several shallow interdunal lakes in southwest Spain are in close hydraulic connection with the shallow ground water. Two permanent lakes and one intermittent lake have chloride concentrations that differ by almost an order of magnitude. A two-dimensional solute-transport model, modified to simulate transient groundwater-lake interaction, suggests that the rising water table during the wet season leads to local flow reversals toward the lakes. Response of the individual lakes, however, varies depending on the lake's position in the regional flow system. The most dilute lake is a flow-through lake during the entire year; the through flow is driven by regional groundwater flow. The other permanent lake, which has a higher solute concentration, undergoes seasonal groundwater flow reversals at its downgradient end, resulting in complex seepage patterns and higher solute concentrations in the ground water near the lake. The solute concentration of the intermittent lake is influenced more strongly by the seasonal wetting and drying cycle than by the regional flow system. Although evaporation is the major process affecting the concentration of conservative solutes in the lakes, geochemical and biochemical reactions influence the concentration of nonconservative solutes. Probable reactions in the lakes include biological uptake of solutes and calcite precipitation; probable reactions as lake water seeps into the aquifer are sulfate reduction and calcite dissolution. Seepage reversals can result in water composition that appears inconsistent with predictions based on head measurements because, under transient flow conditions, the flow direction at any instant may not satisfactorily depict the source of the water. Understanding the dynamic nature of groundwater-lake interaction aids in the interpretation of hydrologic and chemical relations between the lakes and the ground water.

ENVIRONMENTAL RESEARCH BRIEF: USE OF CATIONIC SURFACTANTS TO MODIFY AQUIFER MATERIALS TO REDUCE THE MOBILITY OF HYDROPHOBIC ORGANIC COMPOUNDS

EPA Science Inventory

Cationic surfactants can be used to modify surfaces of soils and subsurface materials to promote sorption of hydrophobic organic compounds (HOC) and retard their migration. For example, cationic surfactants could be injected into an aquifer downgradient from a source of HOC conta...

Predicting hydrology in wetlands designed for coastal stormwater management

Treesearch

William H. Strosnider; Daniel R. Hitchcock; Alan J. Lewitus

2007-01-01

Detention ponds are currently accepted as stormwater best management practices (BMPs) in coastal South Carolina. These ponds are typical catch basins for stormwater piped directly from impervious surfaces in many residential and resort areas. Nutrients often concentrate in the ponds and contribute to eutrophication within the ponds and downgradient estuaries. A...

Modeling contamination of shallow unconfined aquifers through infiltration beds

USGS Publications Warehouse

Ostendorf, D.W.

1986-01-01

We model the transport of a simply reactive contaminant through an infiltration bed and underlying shallow, one-dimensional, unconfined aquifer with a plane, steeply sloping bottom in the assumed absence of dispersion and downgradient dilution. The effluent discharge and ambient groundwater flow under the infiltration beds are presumed to form a vertically mixed plume marked by an appreciable radial velocity component in the near field flow region. The near field analysis routes effluent contamination as a single linear reservoir whose output forms a source plane for the one-dimensional, far field flow region downgradient of the facility; the location and width of the source plane reflect the relative strengths of ambient flow and effluent discharge. We model far field contaminant transport, using an existing method of characteristics solution with frame speeds modified by recharge, bottom slope, and linear adsorption, and concentrations reflecting first-order reaction kinetics. The near and far field models simulate transport of synthetic detergents, chloride, total nitrogen, and boron in a contaminant plume at the Otis Air Force Base sewage treatment plant in Barnstable County, Massachusetts, with reasonable accuracy.

Postconstruction report of the United Nuclear Corporation Disposal Site at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Environmental Restoration Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oakley, L.B.; Siberell, J.K.; Voskuil, T.L.

1993-06-01

Remedial actions conducted under the auspices of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) were completed at the Y-12 United Nuclear Corporation (UNC) Disposal Site in August 1992. The purpose of this Postconstruction Report is to summarize numerous technical reports and provide CERCLA documentation for completion of the remedial actions. Other CERCLA reports, such as the Feasibility Study for the UNC Disposal Site, provide documentation leading up to the remedial action decision. The remedial action chosen, placement of a modified RCRA cap, was completed successfully, and performance standards were either met or exceeded. This remedial action provided solutionsmore » to two environmentally contaminated areas and achieved the goal of minimizing the potential for contamination of the shallow groundwater downgradient of the site, thereby providing protection of human health and the environment. Surveillance and maintenance of the cap will be accomplished to ensure cap integrity, and groundwater monitoring downgradient of the site will continue to confirm the acceptability of the remedial action chosen.« less

Treatment of co-mingled benzene, toluene and TCE in groundwater.

PubMed

Chen, Liang; Liu, Yulong; Liu, Fei; Jin, Song

2014-06-30

This work addressed a hypothetical but practical scenario that includes biological oxidation and reductive dechlorination in treating groundwater containing co-mingled plume of trichloroethene (TCE), benzene and toluene. Groundwater immediately downgradient from the commonly used zero-valent iron (ZVI) has shown alkaline pH (up to 10.7). The elevated pH may influence BTEX compounds (i.e., benzene, toluene, ethyl benzene, and xylenes) biodegradation, which could also be inhibited by elevated concentrations of TCE. Data from this work suggests that the inhibition coefficients (IC) value for 100 μg/L and 500 μg/L of TCE on benzene and toluene degradation are 2.1-2.8 at pH 7.9, and 3.5-6.1 at pH 10.5. For a co-mingled plume, it appears to be more effective to reduce TCE by ZVI before addressing benzene and toluene biodegradation. The ample buffering capacity of most groundwater and the adaptation of benzene and toluene-degrading microbes are likely able to eliminate the adverse influence of pH shifts downgradient from a ZVI-PRB. Copyright © 2014 Elsevier B.V. All rights reserved.

Erkundung und Beweissicherung für eine geothermale Erschließung eines Alpinen Karstaquifers im Tuxertal, Österreich

NASA Astrophysics Data System (ADS)

Sass, Ingo; Heldmann, Claus-Dieter; Schäffer, Rafael

2016-06-01

Karst aquifers may on one hand improve the efficiency of geothermal systems due to increased permeabilities, but on the other hand, high groundwater velocities can reduce the efficiency of the underground heat storage capacity. The marble karst aquifer of the Hochstegen formation was explored and developed for the first time as an intermediate-depth geothermal energy storage system at Finkenberg, Tux valley (Tyrol, Austria). Geological field studies and a spring monitoring program for the project revealed characteristic hydro-chemical signatures related to the catchments in specific tectonic units depending on their lithology. Observations showed that the catchment area of the Hochstegen formation karst aquifer extends up to 2650 m a.s.l. southwest of Finkenberg. In the boreholes, karstification was detected to 400 m below surface (Sass et al., 2016). A monitoring program involving seven springs downgradient of the boreholes has shown that the geothermal project has had no long-term impact on groundwater quality.

Hydrologic conditions in the Bill Williams River National Wildlife Refuge and Planet Valley, Arizona, 2000

USGS Publications Warehouse

Wilson, Richard P.; Owen-Joyce, Sandra J.

2002-01-01

During a period of sustained base-flow conditions in the Bill Williams River below Alamo Dam in west central Arizona from March to July 2000, the channel of the river through Planet Valley was dry, and the water table sloped almost due west parallel to the main slope of the flood plain. Water from the river infiltrated into the channel bottom at the head of Planet Valley, moved downgradient in the subsurface, and reappeared in the channel about 0.3 mile downstream from the east boundary of the Bill Williams River National Wildlife Refuge. A river aquifer in hydraulic connection with the Bill Williams River was mapped from a point 6.3 miles upstream from Highway 95 to the upstream end of Planet Valley. Formations that make up the river aquifer in Planet Valley are younger alluvium, older alluviums, and fanglomerate. Total thickness of the river aquifer probably is less than 200 feet in the bedrock canyons to as much as 1,035 feet in Planet Valley. The purpose of this study was to investigate the current hydrologic conditions along the Bill Williams River, which included an inventory of wells within the river aquifer of the Colorado River and in Planet Valley, and to determine the configuration of the water table. A map shows the elevation and configuration of the water table from the east end of Planet Valley to the confluence of the Bill Williams River with Lake Havasu.

Behavior of a chlorinated ethene plume following source-area treatment with Fenton's reagent

USGS Publications Warehouse

Chapelle, F.H.; Bradley, P.M.; Casey, C.C.

2005-01-01

Monitoring data collected over a 6-year period show that a plume of chlorinated ethene-contaminated ground water has contracted significantly following treatment of the contaminant source area using in situ oxidation. Prior to treatment (1998), concentrations of perchloroethene (PCE) exceeded 4500 ??g/L in a contaminant source area associated with a municipal landfill in Kings Bay, Georgia. The plume emanating from this source area was characterized by vinyl chloride (VC) concentrations exceeding 800 ??g/L. In situ oxidation using Fenton's reagent lowered PCE concentrations in the source area below 100 ??g/L, and PCE concentrations have not rebounded above this level since treatment. In the 6 years following treatment, VC concentrations in the plume have decreased significantly. These concentration declines can be attributed to the movement of Fenton's reagent-treated water downgradient through the system, the cessation of a previously installed pump-and-treat system, and the significant natural attenuation capacity of this anoxic aquifer. While in situ oxidation briefly decreased the abundance and activity of microorganisms in the source area, this activity rebounded in <6 months. Nevertheless, the shift from sulfate-reducing to Fe(III)-reducing conditions induced by Fenton's treatment may have decreased the efficiency of reductive dechlorination in the injection zone. The results of this study indicate that source-area removal actions, particularly when applied to ground water systems that have significant natural attenuation capacity, can be effective in decreasing the areal extent and contaminant concentrations of chlorinated ethene plumes. Copyright ?? 2005 National Ground Water Association.

Characterization of surface and ground water δ18O seasonal variation and its use for estimating groundwater residence times

USGS Publications Warehouse

Reddy, Michael M.; Schuster, Paul; Kendall, Carol; Reddy, Micaela B.

2006-01-01

18O is an ideal tracer for characterizing hydrological processes because it can be reliably measured in several watershed hydrological compartments. Here, we present multiyear isotopic data, i.e. 18O variations (δ18O), for precipitation inputs, surface water and groundwater in the Shingobee River Headwaters Area (SRHA), a well-instrumented research catchment in north-central Minnesota. SRHA surface waters exhibit δ18O seasonal variations similar to those of groundwaters, and seasonal δ18O variations plotted versus time fit seasonal sine functions. These seasonal δ18O variations were interpreted to estimate surface water and groundwater mean residence times (MRTs) at sampling locations near topographically closed-basin lakes. MRT variations of about 1 to 16 years have been estimated over an area covering about 9 km2 from the basin boundary to the most downgradient well. Estimated MRT error (±0·3 to ±0·7 years) is small for short MRTs and is much larger (±10 years) for a well with an MRT (16 years) near the limit of the method. Groundwater transit time estimates based on Darcy's law, tritium content, and the seasonal δ18O amplitude approach appear to be consistent within the limits of each method. The results from this study suggest that use of the δ18O seasonal variation method to determine MRTs can help assess groundwater recharge areas in small headwaters catchments.

Characterization of surface and ground water δ18O seasonal variation and its use for estimating groundwater residence times

USGS Publications Warehouse

Reddy, Michael M.; Schuster, Paul F.; Kendall, Carol; Reddy, Micaela B.

2006-01-01

18O is an ideal tracer for characterizing hydrological processes because it can be reliably measured in several watershed hydrological compartments. Here, we present multiyear isotopic data, i.e. 18O variations (δ18O), for precipitation inputs, surface water and groundwater in the Shingobee River Headwaters Area (SRHA), a well-instrumented research catchment in north-central Minnesota. SRHA surface waters exhibit δ18O seasonal variations similar to those of groundwaters, and seasonal δ18O variations plotted versus time fit seasonal sine functions. These seasonal δ18O variations were interpreted to estimate surface water and groundwater mean residence times (MRTs) at sampling locations near topographically closed-basin lakes. MRT variations of about 1 to 16 years have been estimated over an area covering about 9 km2 from the basin boundary to the most downgradient well. Estimated MRT error (±0·3 to ±0·7 years) is small for short MRTs and is much larger (±10 years) for a well with an MRT (16 years) near the limit of the method. Groundwater transit time estimates based on Darcy's law, tritium content, and the seasonal δ18O amplitude approach appear to be consistent within the limits of each method. The results from this study suggest that use of the δ18O seasonal variation method to determine MRTs can help assess groundwater recharge areas in small headwaters catchments.

Delineation of the Pahute Mesa–Oasis Valley groundwater basin, Nevada

USGS Publications Warehouse

Fenelon, Joseph M.; Halford, Keith J.; Moreo, Michael T.

2016-01-22

This report delineates the Pahute Mesa–Oasis Valley (PMOV) groundwater basin, where recharge occurs, moves downgradient, and discharges to Oasis Valley, Nevada. About 5,900 acre-feet of water discharges annually from Oasis Valley, an area of springs and seeps near the town of Beatty in southern Nevada. Radionuclides in groundwater beneath Pahute Mesa, an area of historical underground nuclear testing at the Nevada National Security Site, are believed to be migrating toward Oasis Valley. Delineating the boundary of the PMOV groundwater basin is necessary to adequately assess the potential for transport of radionuclides from Pahute Mesa to Oasis Valley.The PMOV contributing area is defined based on regional water-level contours, geologic controls, and knowledge of adjacent flow systems. The viability of this area as the contributing area to Oasis Valley and the absence of significant interbasin flow between the PMOV groundwater basin and adjacent basins are shown regionally and locally. Regional constraints on the location of the contributing area boundary and on the absence of interbasin groundwater flow are shown by balancing groundwater discharges in the PMOV groundwater basin and adjacent basins against available water from precipitation. Internal consistency for the delineated contributing area is shown by matching measured water levels, groundwater discharges, and transmissivities with simulated results from a single-layer, steady-state, groundwater-flow model. An alternative basin boundary extending farther north than the final boundary was rejected based on a poor chloride mass balance and a large imbalance in the northern area between preferred and simulated recharge.

Relation of electrochemical potentials and iron content to ground-water flow patterns

USGS Publications Warehouse

Back, William; Barnes, Ivan

1965-01-01

This study was undertaken to develop means of measuring oxidation potentials in aquifer systems and to use the measured values in interpreting the behavior of iron in ground water. Anne Arundel County, Md., was selected as the area of study because of the wide range of concentration of iron-nearly zero to about 35 ppm-in the ground water and the rather complete information on the geology and hydrology. The regional geology consists of coastal plain sediments ranging in age from Early Cretaceous through the Recent. Most of the pH and oxidation-potential measurements were made in nonmarine Cretaceous deposits, only a few in the marine Eocene. Iron-bearing minerals in the area are primarily hematite or limonite and glauconite with a small amount of pyrite. Equipment was developed that permits the measurement of oxidation potentials by use of saturated calomel and platinum electrodes in ground-water samples uncontaminated by oxygen of the atmosphere. Measured Eh values range from about +700 mv to -40 mv. Approximately 2 to 3 hours are required to measure a stable or nearly stable oxidation potential. The mineralogy and organic content of the deposits and the ground-water flow pattern are the primary controls on the oxidation potential and pH of the water. A correlation exists between the oxidation potential and the concentration of iron in ground water; the higher concentrations occur in waters with the lowest values of Eh. The concentration of iron in the water tested shows little correlation with the pH of the water. The highest oxidation potentials were measured in water produced from shallow wells and those wells in recharge areas. The lowest potentials were measured farthest downgradient in water associated with gray and green sediments. The Eh values measured in the field are between values predicted from the solubility of Fe(OH)2(c) and values predicted from the solubility of hematite.

Occurrence of steroid hormones and antibiotics in shallow groundwater impacted by livestock waste control facilities

NASA Astrophysics Data System (ADS)

Bartelt-Hunt, Shannon; Snow, Daniel D.; Damon-Powell, Teyona; Miesbach, David

2011-04-01

Wastewater impoundments at concentrated animal feeding operations (CAFOs) represent a potential source of veterinary pharmaceuticals and steroid hormone contamination to shallow groundwater. This study investigates the occurrence of seventeen veterinary pharmaceuticals and thirteen steroid hormones and hormone metabolites in lagoons and adjacent groundwater at operating swine and beef cattle facilities. These sites were chosen because subsurface geology and previous monitoring of nitrate, ammonia and chloride levels in shallow ground water strongly indicated direct infiltration, and as such represent worst cases for ground water contamination by waste water. Pharmaceutical compounds detected in samples obtained from cattle facilities include sulfamerazine; sulfamethazine; erythromycin; monensin; tiamulin; and sulfathiazole. Lincomycin; ractopamine; sulfamethazine; sulfathiazole; erythromycin; tiamulin and sulfadimethoxine were detected in wastewater samples obtained from swine facilities. Steroid hormones were detected less frequently than veterinary pharmaceuticals in this study. Estrone, testosterone, 4-androstenedione, and androsterone were detected in wastewater impoundments at concentrations ranging from 30 to 3600 ng/L, while only estrone and testosterone were detected in groundwater samples at concentrations up to 390 ng/L. The co-occurrence of veterinary pharmaceutical and steroid hormone contamination in groundwater at these locations and the correlation between pharmaceutical occurrence in lagoon wastewater and hydraulically downgradient groundwater indicates that groundwater underlying some livestock wastewater impoundments is susceptible to contamination by veterinary pharmaceuticals and steroid hormones originating in wastewater lagoons.

Investigation of Contaminated Ground Water at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina, 2006-2007

USGS Publications Warehouse

Vroblesky, Don A.; Petkewich, Matthew D.; Lowery, Mark A.; Conlon, Kevin J.; Harrelson, Larry G.

2008-01-01

The U.S. Geological Survey investigated natural and engineered remediation of chlorinated volatile organic compound (VOC) ground-water contamination at Solid Waste Management Unit 12 at the Naval Weapons Station Charleston, North Charleston, South Carolina, beginning in 2000. The primary contaminants of interest in the study are tetrachloroethene, 1,1,1-trichloroethane, trichloroethene, cis-1,2-dichloroethene, vinyl chloride, 1,1-dichloroethane, and 1,1-dichloroethene. The permeable reactive barrier (PRB) along the main axis of the contaminant plume appears to be actively removing contamination. In contrast to the central area of the PRB, the data from the southern end of the PRB indicate that contaminants are moving around the PRB. Concentrations in wells 12MW-10S and 12MW-03S, upgradient from the PRB, showed a general decrease in VOC concentrations. VOC concentrations in some wells in the forest showed a sharp increase, followed by a decrease. In 2007, the VOC concentrations began to increase in well 12MW-12S, downgradient from the PRB and thought to be unaffected by the PRB. The VOC-concentration changes in the forest, such as at well 12MW-12S, may represent lateral shifting of the plume in response to changes in ground-water-flow direction or may represent movement of a contamination pulse through the forest.

Hydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake

USGS Publications Warehouse

Stoliker, Deborah L.; Repert, Deborah A.; Smith, Richard L.; Song, Bongkeun; LeBlanc, Denis R.; McCobb, Timothy D.; Conaway, Christopher; Hyun, Sung Pil; Koh, Dong-Chan; Moon, Hee Sun; Kent, Douglas B.

2016-01-01

The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water chemistry, seepage rates and direction of groundwater flow, and the abundance and potential rates of activity of N-cycling microbial communities. Genes coding for denitrification, anaerobic ammonium oxidation (anammox), and nitrification were identified at all sites regardless of flow direction or groundwater dissolved oxygen concentrations. Flow direction was, however, a controlling factor in the potential for N-attenuation via denitrification in the sediments. Potential rates of denitrification varied from 6 to 4500 pmol N/g/h from the inflow to the outflow side of the lake, owing to fundamental differences in the supply of labile organic matter. The results of laboratory incubations suggested that when anoxia and limiting labile organic matter prevailed, the potential existed for concomitant anammox and denitrification. Where oxic lake water was downwelling, potential rates of nitrification at shallow depths were substantial (1640 pmol N/g/h). Rates of anammox, denitrification, and nitrification may be linked to rates of organic N-mineralization, serving to increase N-mobility and transport downgradient.

Transport and transformations of chlorinated-solvent contamination in a saprolite and fractured rock aquifer near a former wastewater-treatment plant, Greenville, South Carolina

USGS Publications Warehouse

Vroblesky, D.A.; Bradley, P.M.; Lane, J.W.; Robertson, J.F.

1997-01-01

The transport and fate of chlorinated-ethene contamination was investigated in a fractured-rock aquifer downgradient from a wastewater-treatment plant at a gas-turbine manufacturing facility in Greenville, South Carolina. A vapor-diffusion-sampler technique, developed for this investigation, located fracture zones that discharged contaminated ground water to surface water. The distribution of chlorinated compounds and sulfate, comparison of borehole geophysical data, driller's logs, and the aquifer response to pumpage allowed subsurface contaminant-transport pathways to be delineated.The probable contaminant-transport pathway from the former aeration lagoon was southward. The probable pathway of contaminant transport from the former sludge lagoon was southward to and beneath Little Rocky Creek. South of the creek, the major pathway of contaminant transport appeared to be at a depth of approximately 80 to 107 feet below land surface. The contaminant-transport pathway from the former industrial lagoon was not readily discernible from existing data. A laboratory investigation, as well as examination of ground- water-chemistry data collected during this investigation and concentrations of chlorinated compounds collected during previous investigations,indicates that higher chlorinated compounds are being degraded to lower-chlorinated compounds in the contaminated aquifer. The approaches used in this investigation, as well as the findings, have potential application to other fractured-rock aquifers contaminated by chlorinated ethenes.

Assessment of intrinsic bioremediation of jet fuel contamination in a shallow aquifer, Beaufort, South Carolina

USGS Publications Warehouse

Chapelle, Frank; Landmeyer, J.E.; Bradley, P.M.

1995-01-01

Field and laboratory studies show that microorganisms indigenous to the ground-water system underlying Tank Farm C, Marine Corps Air Station Beaufort, S.C., degrade petroleum hydrocarbons under aerobic and anaerobic conditions. Under aerobic conditions, sediments from the shallow aquifer underlying the site mineralized radiolabeled (14C) toluene to 14CO2 with first-order rate constants of about -0.29 per day. Sediments incubated under anaerobic conditions mineralized radiolabeled toluene more slowly, with first-order rate constants of -0.001 per day. Although anaerobic rates of biodegradation are low, they are significant in the hydrologic and geochemical context of the site. Because of low hydraulic conductivities (1.9-9.1 feet per day) and low hydraulic gradients (about 0.004 feet per feet), ground water flows slowly (approximately 20 feet per year) at this site. Furthermore, aquifer sediments contain organic-rich peat that has a high sorptive capacity. Under these conditions, hydrocarbon contaminants have moved no further than 10 feet downgradient of the jet fuel free product. Digital solute-transport simulations, using the range of model parameters measured at the site, show that dissolved contaminants will be completely degraded before they are discharged from the aquifer into adjacent surface-water bodies. These results show that natural attenuation processes are containing the migration of soluble hydrocarbons, and that intrinsic bioremediation is a potentially effective remedial strategy at this site.

Hydrologic Controls on Nitrogen Cycling Processes and Functional Gene Abundance in Sediments of a Groundwater Flow-Through Lake.

PubMed

Stoliker, Deborah L; Repert, Deborah A; Smith, Richard L; Song, Bongkeun; LeBlanc, Denis R; McCobb, Timothy D; Conaway, Christopher H; Hyun, Sung Pil; Koh, Dong-Chan; Moon, Hee Sun; Kent, Douglas B

2016-04-05

The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water chemistry, seepage rates and direction of groundwater flow, and the abundance and potential rates of activity of N-cycling microbial communities. Genes coding for denitrification, anaerobic ammonium oxidation (anammox), and nitrification were identified at all sites regardless of flow direction or groundwater dissolved oxygen concentrations. Flow direction was, however, a controlling factor in the potential for N-attenuation via denitrification in the sediments. Potential rates of denitrification varied from 6 to 4500 pmol N/g/h from the inflow to the outflow side of the lake, owing to fundamental differences in the supply of labile organic matter. The results of laboratory incubations suggested that when anoxia and limiting labile organic matter prevailed, the potential existed for concomitant anammox and denitrification. Where oxic lake water was downwelling, potential rates of nitrification at shallow depths were substantial (1640 pmol N/g/h). Rates of anammox, denitrification, and nitrification may be linked to rates of organic N-mineralization, serving to increase N-mobility and transport downgradient.

Water budget and simulation of one-dimensional unsaturated flow for a flood- and a sprinkler-irrigated field near Milford, Utah

USGS Publications Warehouse

Susong, David D.

1995-01-01

Ground-water recharge to basin-fill aquifers from unconsumed irrigation water in the western United States is being reduced as irrigators convert to more efficient irrigation systems. In some areas, these changes in irrigation methods may be contributing to ground-water-level declines and reducing the quantity of water available to downgradient users. The components of the water budget were measured or calculated for each field for the 1992 and 1993 irrigation seasons. Precipitation was about 6.5 cm (2.6 inches) both years. The flood-irrigated field received 182 and 156 centimeters (71.6 and 61.4 inches) of irrigation water in 1992 and 1993, and the sprinkler-irrigated field received 52.8 and 87.2 centimeters (20.8 and 34.3 inches) of water, respectively. Evapotranspiration for alfalfa was calculated using the Penman-Monteith combination equation and was 95.4 and 84.3 centimeters (37.2 and 33.2 inches) for 1992 and 1993, respectively. No runoff and no significant change in soil moisture in storage was observed from either field. Recharge to the aquifer from the flood-irrigated field was 93.3 and 78.1 centimeters (36.7 and 30.7 inches) in 1992 and 1993 and from the sprinkler-irrigated field was -35.9 and 9.3 centimeters (-14.1 and 3.7 inches), respectively. The daily water budget and soil-moisture profiles in the upper 6.4 meters (21 feet) of the unsaturated zone were simulated with an unsaturated flow model for average climate conditions. Simulated recharge was 57.4 and 50.5 percent of the quantity of irrigation water applied to the flood-irrigated field during 1992 and 1993, respectively, and was 8.7 and 13.8 percent of the quantity of irrigation water applied to the sprinkler- irrigated field.

Water budget and simulation of one-dimensional unsaturated flow for a flood- and a sprinkler-irrigated field near Milford, Utah

USGS Publications Warehouse

Susong, D.D.

1995-01-01

Ground-water recharge to basin-fill aquifers from unconsumed irrigation water in the western United States is being reduced as irrigators convert to more efficient irrigation systems. In some areas, these changes in irrigation methods may be contributing to ground-water-level declines and reducing the quantity of water available to downgradient users. The components of the water budget were measured or calculated for each field for the 1992 and 1993 irrigation seasons. Precipitation was about 6.5 cm (2.6 inches) both years. The flood-irrigated field received 182 and 156 centimeters (71.6 and 61.4 inches) of irrigation water in 1992 and 1993, and the sprinkler-irrigated field received 52.8 and 87.2 centimeters (20.8 and 34.3 inches) of water, respectively. Evapotrans- piration for alfalfa was calculated using the Penman-Monteith combination equation and was 95.4 and 84.3 centimeters (37.2 and 33.2 inches) for 1992 and 1993, respectively. No runoff and no signifi- cant change in soil moisture in storage was observed from either field. Recharge to the aquifer from the flood-irrigated field was 93.3 and 78.1 centimeters (36.7 and 30.7 inches) in 1992 and 1993 and from the sprinkler-irrigated field was -35.9 and 9.3 centimeters (-14.1 and 3.7 inches), respectively. The daily water budget and soil-moisture profiles in the upper 6.4 meters (21 feet) of the unsaturated zone were simulated with an unsaturated flow model for average climate conditions. Simulated recharge was 57.4 and 50.5 percent of the quantity of irrigation water applied to the flood-irrigated field during 1992 and 1993, respectively, and was 8.7 and 13.8 percent of the quantity of irrigation water applied to the sprinkler-irrigated field.

Ground-water contamination from lead shot at Prime Hook National Wildlife Refuge, Sussex County, Delaware

USGS Publications Warehouse

Soeder, Daniel J.; Miller, Cherie V.

2003-01-01

Prime Hook National Wildlife Refuge is located in southeastern Delaware in coastal lowlands along the margin of Delaware Bay. For 37 years, the Broadkiln Sportsman?s Club adjacent to the refuge operated a trap-shooting range, with the clay-target launchers oriented so that the expended lead shot from the range dropped into forested wetland areas on the refuge property. Investigators have estimated that up to 58,000 shotgun pellets per square foot are present in locations on the refuge where the lead shot fell to the ground. As part of the environmental risk assessment for the site, the U.S. Geological Survey (USGS) investigated the potential for lead contamination in ground water. Results from two sampling rounds in 19 shallow wells indicate that elevated levels of dissolved lead are present in ground water at the site. The lead and associated metals, such as antimony and arsenic (common shotgun pellet alloys), are being transported along shallow ground-water flowpaths toward an open-water slough in the forested wetland adjacent to the downrange target area. Water samples from wells located along the bank of the slough contained dissolved lead concentrations higher than 400 micrograms per liter, and as high as 1 milligram per liter. In contrast, a natural background concentration of lead from ground water in a well upgradient from the site is about 1 microgram per liter. Two water samples collected several months apart from the slough directly downgradient of the shooting range contained 24 and 212 micrograms per liter of lead, respectively. The data indicate that lead from a concentrated deposit of shotgun pellets on the refuge has been mobilized through a combination of acidic water conditions and a very sandy, shallow, unconfined aquifer, and is moving along ground-water flowpaths toward the surface-water drainage. Data from this study will be used to help delineate the lead plume, and determine the fate and transport of lead from the source area.

Recharge sources and residence times of groundwater as determined by geochemical tracers in the Mayfield Area, southwestern Idaho, 2011–12

USGS Publications Warehouse

Hopkins, Candice B.

2013-01-01

Parties proposing residential development in the area of Mayfield, Idaho are seeking a sustainable groundwater supply. During 2011–12, the U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources, used geochemical tracers in the Mayfield area to evaluate sources of aquifer recharge and differences in groundwater residence time. Fourteen groundwater wells and one surface-water site were sampled for major ion chemistry, metals, stable isotopes, and age tracers; data collected from this study were used to evaluate the sources of groundwater recharge and groundwater residence times in the area. Major ion chemistry varied along a flow path between deeper wells, suggesting an upgradient source of dilute water, and a downgradient source of more concentrated water with the geochemical signature of the Idaho Batholith. Samples from shallow wells had elevated nutrient concentrations, a more positive oxygen-18 signature, and younger carbon-14 dates than deep wells, suggesting that recharge comes from young precipitation and surface-water infiltration. Samples from deep wells generally had higher concentrations of metals typical of geothermal waters, a more negative oxygen-18 signature, and older carbon-14 values than samples from shallow wells, suggesting that recharge comes from both infiltration of meteoric water and another source. The chemistry of groundwater sampled from deep wells is somewhat similar to the chemistry in geothermal waters, suggesting that geothermal water may be a source of recharge to this aquifer. Results of NETPATH mixing models suggest that geothermal water composes 1–23 percent of water in deep wells. Chlorofluorocarbons were detected in every sample, which indicates that all groundwater samples contain at least a component of young recharge, and that groundwater is derived from multiple recharge sources. Conclusions from this study can be used to further refine conceptual hydrological models of the area.

Potential effects of regional pumpage on groundwater age distribution

USGS Publications Warehouse

Zinn, Brendan A.; Konikow, Leonard F.

2007-01-01

Groundwater ages estimated from environmental tracers can help calibrate groundwater flow models. Groundwater age represents a mixture of traveltimes, with the distribution of ages determined by the detailed structure of the flow field, which can be prone to significant transient variability. Effects of pumping on age distribution were assessed using direct age simulation in a hypothetical layered aquifer system. A steady state predevelopment age distribution was computed first. A well field was then introduced, and pumpage caused leakage into the confined aquifer of older water from an overlying confining unit. Large changes in simulated groundwater ages occurred in both the aquifer and the confining unit at high pumping rates, and the effects propagated a substantial distance downgradient from the wells. The range and variance of ages contributing to the well increased substantially during pumping. The results suggest that the groundwater age distribution in developed aquifers may be affected by transient leakage from low‐permeability material, such as confining units, under certain hydrogeologic conditions.

Concentrations and speciation of arsenic along a groundwater flow-path in the Upper Floridan aquifer, Florida, USA

NASA Astrophysics Data System (ADS)

Haque, S. E.; Johannesson, K. H.

2006-05-01

Arsenic (As) concentrations and speciation were determined in groundwaters along a flow-path in the Upper Floridan aquifer (UFA) to investigate the biogeochemical “evolution“ of As in this relatively pristine aquifer. Dissolved inorganic As species were separated in the field using anion-exchange chromatography and subsequently analyzed by inductively coupled plasma mass spectrometry. Total As concentrations are higher in the recharge area groundwaters compared to down-gradient portions of UFA. Redox conditions vary from relatively oxic to anoxic along the flow-path. Mobilization of As species in UFA groundwaters is influenced by ferric iron reduction and subsequent dissolution, sulfate reduction, and probable pyrite precipitation that are inferred from the data to occur along distinct regions of the flow-path. In general, the distribution of As species are consistent with equilibrium thermodynamics, such that arsenate dominates in more oxidizing waters near the recharge area, and arsenite predominates in the progressively reducing groundwaters beyond the recharge area.

Groundwater from Lower Cretaceous rocks in Kansas

USGS Publications Warehouse

Keene, Katherine M.; Bayne, Charles Knight

1976-01-01

Sandstones in Lower Cretaceous rocks contain supplies, of water that may be adequate to meet increasing present and future demands for supplemental municipal and domestic use in central and western Kansas. An estimated 70 to 80 million acre-feet (86,000 to 99,000 cubic hectometers) of water containing less than 1,000 milligrams per liter dissolved solids may be acceptable for use at the present (1976). An additional 10 to 15 million acre-feet (12,000 to 18,000 cubic hectometers) containing 1,000 to 3,000 milligrams per liter dissolved solids is estimated to be available for use in the future with appropriate desalinization. Lower Cretaceous rocks crop out from Washington County on the north to Comanche County on-the south. The rocks dip from a structural high in the southwest part of the State to structural lows in the northwest and north-central part. Depth below land surface increases generally northwestward to about 2,600 feet (790 meters); thickness of the rocks increases westward, nearly zero to about 850 feet (260 meters). The rocks consist chiefly of marine to nonmarine shale and silt- stone interbedded with coastal to deltaic sandstone. The interbedded sandstone, which composes about one-third of the rocks, consists of one or more lenses that thicken westward to about 400 feet (120 meters) in the central part of western Kansas. The yield of water to individual wells is related to areal extent, thickness, and interconnection of the sand lenses and to grain size and cementation of the sand. Large amounts of water may be pumped by wells where loosely cemented sand lenses are interconnected. Wells commonly yield adequate supplies for domestic and stock use; reported yields from municipal and irrigation wells range from about 100 to 2,000 gallons per minute (6 to 125 liters per second). Recharge to the Lower Cretaceous-rocks occurs in the area of outcrop and from hydraulically connected saturated Cenozoic rocks, especially in the southern part of the State. Movement of water is principally northeastward from areas of recharge to areas of discharge where streams intersect the sandstone outcrops. Water in the sandstone aquifers commonly is confined between beds of relatively impermeable shale, causing water in wells to rise above the top of the aquifer. Water levels fluctuate in response to changes in atmospheric pressure, recharge, and discharge; greatest fluctuations result from discharge to wells for municipal and irrigation use. Progressive declines in water levels have occurred where irrigation withdrawals exceed recharge. Calcium bicarbonate water is dominant near recharge areas; mixed sodium and calcium bicarbonate water and sodium chloride water become successively dominant as the water moves downgradient from the recharge areas. The quality of water ranges from fresh to very saline (less than 1.000 to 35,000 milligrams per liter dissolved solids). In the areas of generally fresh water, localized areas of calcium sulfate water result from solution of gypsum in the Kiowa Formation, and areas of sodium chloride water result from contamination by oil-field brines.

Investigation of Ground-Water Contamination at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina

USGS Publications Warehouse

Vroblesky, Don A.; Casey, Clifton C.; Petkewich, Matthew D.; Lowery, Mark A.; Conlon, Kevin J.; Harrelson, Larry G.

2007-01-01

The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated natural and engineered remediation of chlorinated volatile organic compound ground-water contamination at Solid Waste Management Unit 12 at the Naval Weapons Station Charleston, North Charleston, South Carolina. The primary contaminants of interest are tetrachloroethene, 1,1,1-trichloroethane, trichloroethene, cis-1,2-dichloroethene, vinyl chloride, 1,1-dichloroethane, and 1,1-dichloroethene. In general, the hydrogeology of Solid Waste Management Unit 12 consists of a surficial aquifer, composed of sand to clayey sand, overlain by dense clay that extends from about land surface to a depth of about 8 to 10 feet and substantially limits local recharge. During some months in the summer, evapotranspiration and limited local recharge result in ground-water level depressions in the forested area near wells 12MW-12S and 12MW-17S, seasonally reflecting the effects of evapotranspiration. Changes in surface-water levels following Hurricane Gaston in 2004 resulted in a substantial change in the ground-water levels at the site that, in turn, may have caused lateral shifting of the contaminant plume. Hydraulic conductivity, determined by slug tests, is higher along the axis of the plume in the downgradient part of the forests than adjacent to the plume, implying that there is some degree of lithologic control on the plume location. Hydraulic conductivity, hydraulic gradient, sulfur-hexafluoride measurements, and historical data indicate that ground-water flow rates are substantially slower in the forested area relative to upgradient areas. The ground-water contamination, consisting of chlorinated volatile organic compounds, extends eastward in the surficial aquifer from the probable source area near a former underground storage tank. Engineered remediation approaches include a permeable reactive barrier and phytoremediation. The central part of the permeable reactive barrier along the main axis of the contaminant plume appears to be actively removing contamination; however, ground-water contamination is moving around the southern end of the permeable reactive barrier. Changes in the contaminant concentrations along the path of ground-water transport reflect a complex variety of influences. Potential influences include dechlorination, sorption and desorption, transpirative removal by trees, lateral shifting of the plume, and the presence of zones of differing concentrations possibly reflecting one or more pulse releases of contamination from the source area. Near the source area at well 12MW-10S, volatile organic compound concentrations of cis-1,2-dichlorothene, vinyl chloride, 1,1-dichloroethane, and 1,1,1-trichloroethane continued an irregular decline, while tetrachloroethene and 1,1-dichloroethene showed marked fluctuations in concentration during 2005 and 2006. Volatile organic compound concentrations at well 12MW-03S continued to show decreasing concentrations with the June 2006 concentrations being the lowest yet recorded at that well for several volatile organic compounds. Concentration and delta carbon 13 data indicate that in the upgradient part of the plume, tetrachloroethene is being degraded to trichloroethene, which is being degraded to cis-1,2-dichloroethene, and cis-1,2-dichloroethene is accumulating faster than it is being depleted. Ground-water volatile organic compound concentrations also changed in some wells in the forested area in the midpart of the plume. Increasing tetrachloroethene and decreasing trichloroethene and 1,1-dichloroethene concentrations were observed at wells 12MW-05S and 12MW-29S, possibly reflecting a lateral shift in the axis of the contamination plume or an advancing contamination pulse. Substantial decreases in contamination occur in the forested area downgradient from well 12MW-05S. Probable major loss mechanisms in this area include evapotranspiration and sorption.

Preliminary report on the geology and hydrology of Mortandad Canyon near Los Alamos, New Mexico, with reference to disposal of liquid low-level radioactive waste

USGS Publications Warehouse

Baltz, E.H.; Abrahams, J.H.; Purtyman, W.D.

1963-01-01

The U.S. Geological Survey, in cooperation with the U.S. Atomic Energy Commission and the Los Alamos Scientific Laboratory, selected the upper part of Mortandad Canyon near Los Alamos, New Mexico for a site for disposal of treated liquid low-level radioactive waste. This report summarizes the part of a study of the geology and hydrology that was done from October 1960 through June 1961. Additional work is being continued. Mortandad Canyon is a narrow east-southeast-trending canyon about 9? miles long that heads on the central part of the Pajarito Plateau at an altitude of about 7,340 feet. The canyon is tributary to the Rio Grande. The drainage area of the part of Mortandad Canyon that was investigated is about 2 square miles, and the total drainage area is about 4.9 square miles. The Pajarito Plateau is capped by the Bandelier Tuff of Pleistocene age. Mortandad Canyon is cut in the Bandelier, and alluvium covers the floor of the canyon to depths ranging from less than 1 foot to as much as 100 feet. The Bandelier is underlain by silt, sand, conglomerate, and interbedded basalt of the Santa Fe Group of Miocene, Pliocene, and Pleistocene(?) age. Some ground water is perched in the alluvium in the canyon; however, the top of the main aquifer is in the Santa Fe Group at a depth of about 990 feet below the canyon floor. Joints in the Bandelier Tuff probably were caused by shrinkage of the tuff during cooling. The joints range in width from hairline cracks to fissures several inches wide. Water can infiltrate along the open joints where the Bandelier is at the surface; however, soil, alluvial fill, and autochthonous clay inhibit infiltration on the tops of mesas and probably in the alluvium-floored canyons also. Thirty-three test holes, each less than 100 feet deep, were drilled in 10 lies across Mortandad Canyon from the western margin of the study area to just west of the Los Alamos-Santa Fe County line. Ten of the holes were cased for observation wells to measure water levels and collect water samples from the alluvium. Twenty-three of the holes were cased to seal out water and were used as access tubes to accommodate a neutron-neutron probe for determining the moisture content of the alluvium and tuff. The source of recharge for the perched ground-water body in the alluvium in Mortandad Canyon is the precipitation in the drainage area of the canyon. During the winter of 1960-61, a snowpack 1-2 feet thick accumulated in the narrow shaded upper part of the canyon. The alluvium below the snowpack received some recharge because of diurnal melting during the winter. In March 1961 the snowmelt water saturated most of the thin alluvium in the upper part of the canyon, and a surface stream began to flow on the alluvium. The maximum flow of the stream was about 250 gpm (gallons per minute). Water from the stream infiltrated the alluvium at the front of the stream and in the reach upstream from the front. A ground-water mound was formed beneath the channel by water infiltrating from the stream. The front of the stream and the front of the ground-water mound advanced eastward to about the middle of the area studied. From this point eastward, the alluvium was thick enough to absorb and transmit the amount of flow in 1961. Late in April the front of the stream retreated, and by the first of May the flow stopped. During and after this period the ground-water mound decayed, and ground-water levels declined in the upper part of the canyon as water drained into the channel and downgradient through the alluvium. The amount of recharge was small in the wide lower part of the canyon during the period of study. The rise in ground-water levels and the increase in moisture content of the alluvium in the lower part of the canyon indicate that water moved downgradient by underflow through the alluvium from the recharge area in the upper part of the canyon. Moisture measurements indicate that only a little water moved into the underlyin

76 FR 20546 - National Oil and Hazardous Substance Pollution Contingency Plan; National Priorities List...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-13

... files should avoid the use of special characters, any form of encryption, and be free of any defects or... through the present time. The property is surrounded by woods, open fields, and rural residences. A paint..., chloroethane, 2-hexanone, cadmium, nickel, and lead. The detection of organic constituents in downgradient...

40 CFR 257.5 - Disposal standards for owners/operators of non-municipal non-hazardous waste disposal units that...

Code of Federal Regulations, 2010 CFR

2010-07-01

... compliance with §§ 257.7 through 257.30 prior to the receipt of CESQG hazardous waste. (b) Definitions.... Waste management unit boundary means a vertical surface located at the hydraulically downgradient limit.../operators of non-municipal non-hazardous waste disposal units that receive Conditionally Exempt Small...

Hydrogeology and water quality in the Snake River alluvial aquifer at Jackson Hole Airport, Jackson, Wyoming, water years 2011 and 2012

USGS Publications Warehouse

Wright, Peter R.

2013-01-01

The hydrogeology and water quality of the Snake River alluvial aquifer at the Jackson Hole Airport in northwest Wyoming was studied by the U.S. Geological Survey, in cooperation with the Jackson Hole Airport Board, during water years 2011 and 2012 as part of a followup to a previous baseline study during September 2008 through June 2009. Hydrogeologic conditions were characterized using data collected from 19 Jackson Hole Airport wells. Groundwater levels are summarized in this report and the direction of groundwater flow, hydraulic gradients, and estimated groundwater velocity rates in the Snake River alluvial aquifer underlying the study area are presented. Analytical results of groundwater samples collected from 10 wells during water years 2011 and 2012 are presented and summarized. The water table at Jackson Hole Airport was lowest in early spring and reached its peak in July or August, with an increase of 12.5 to 15.5 feet between April and July 2011. Groundwater flow was predominantly horizontal but generally had the hydraulic potential for downward flow. Groundwater flow within the Snake River alluvial aquifer at the airport was from the northeast to the west-southwest, with horizontal velocities estimated to be about 25 to 68 feet per day. This range of velocities slightly is broader than the range determined in the previous study and likely is due to variability in the local climate. The travel time from the farthest upgradient well to the farthest downgradient well was approximately 52 to 142 days. This estimate only describes the average movement of groundwater, and some solutes may move at a different rate than groundwater through the aquifer. The quality of the water in the alluvial aquifer generally was considered good. Water from the alluvial aquifer was fresh, hard to very hard, and dominated by calcium carbonate. No constituents were detected at concentrations exceeding U.S. Environmental Protection Agency maximum contaminant levels or health advisories; however, reduction and oxidation (redox) measurements indicate oxygen-poor water in many of the wells. Gasoline-range organics, three volatile organic compounds, and triazoles were detected in some groundwater samples. The quality of groundwater in the alluvial aquifer generally was suitable for domestic and other uses; however, dissolved iron and manganese were detected in samples from many of the monitor wells at concentrations exceeding U.S. Environmental Protection Agency secondary maximum contaminant levels. Iron and manganese likely are both natural components of the geologic materials in the area and may have become mobilized in the aquifer because of redox processes. Additionally, measurements of dissolved-oxygen concentrations and analyses of major ions and nutrients indicate reducing conditions exist at 7 of the 10 wells sampled. Measurements of dissolved-oxygen concentrations (less than 0.1 to 9 milligrams per liter) indicated some variability in the oxygen content of the aquifer. Dissolved-oxygen concentrations in samples from 3 of the 10 wells indicated oxic conditions in the aquifer, whereas low dissolved-oxygen concentrations (less than 1 milligram per liter) in samples from 7 wells indicated anoxic conditions. Nutrients were present in low concentrations in all samples collected. Nitrate plus nitrite was detected in samples from 6 of the 10 monitored wells, whereas dissolved ammonia was detected in small concentrations in 8 of the 10 monitored wells. Dissolved organic carbon concentrations generally were low. At least one dissolved organic carbon concentration was quantified by the laboratory in samples from all 10 wells; one of the concentrations was an order of magnitude higher than other detected dissolved organic carbon concentrations, and slightly exceeded the estimated range for natural groundwater. Samples were collected for analyses of dissolved gases, and field analyses of ferrous iron, hydrogen sulfide, and low-level dissolved oxygen were completed to better understand the redox conditions of the alluvial aquifer. Dissolved gas analyses confirmed low concentrations of dissolved oxygen in samples from wells where reducing conditions exist and indicated the presence of methane gas in samples from several wells. Redox processes in the alluvial aquifer were identified using a model designed to use a multiple-lines-of-evidence approach to distinguish reduction processes. Results of redox analyses indicate iron reduction was the dominant redox process; however, the model indicated manganese reduction and methanogenesis also were taking place in the aquifer. Each set of samples collected during this study included analysis of at least two, but often many anthropogenic compounds. During the previous 2008–09 study at Jackson Hole Airport, diesel-range organics were measured in small (estimated) concentrations in several samples. Samples collected from all 10 wells sampled during the 2011–12 study were analyzed for diesel-range organics, and there were no detections; however, several other anthropogenic compounds were detected in groundwater samples during water years 2011—12 that were not detected during the previous 2008–09 study. Gasoline-range organics, benzene, ethylbenzene, and total xylene were each detected (but reported as estimated concentrations) in at least one groundwater sample. These compounds were not detected during the previous study or consistently during this study. Several possible reasons these compounds were not detected consistently include (1) these compounds are present in the aquifer at concentrations near the analytical method detection limit and are difficult to detect, (2) these compounds were not from a persistent source during this study, and (3) these compounds were detected because of contamination introduced during sampling or analysis. During water years 2011–2012, groundwater samples were analyzed for triazoles, specifically benzotriazole, 4-methyl-1H-benzotriazole, and 5-methyl-1H-benzotriazole. Triazoles are anthropogenic compounds often used as an additive in deicing and anti-icing fluids as a corrosion inhibitor, and can be detected at lower laboratory reporting levels than glycols, which previously had not been detected. Two of the three triazoles measured, 4-methyl-1H-benzotriazole and 5-methyl-1H-benzotriazole, were detected at low concentrations in groundwater at 7 of the 10 wells sampled. The detection of triazole compounds in groundwater downgradient from airport operations makes it unlikely there is a natural cause for the high rates of reduction present in many airport monitor wells. It is more likely that aircraft deicers, anti-icers, or pavement deicers have seeped into the groundwater system and caused the reducing conditions.

Hydrologic Evaluation of the Jungo Area, Southern Desert Valley, Nevada

USGS Publications Warehouse

Lopes, Thomas J.

2010-01-01

RecologyTM, the primary San Francisco waste-disposal entity, is proposing to develop a Class 1 landfill near Jungo, Nevada. The proposal calls for the landfill to receive by rail about 20,000 tons of waste per week for up to 50 years. On September 22, 2009, the Interior Appropriation (S.A. 2494) was amended to require the U.S. Geological Survey to evaluate the proposed Jungo landfill site for: (1) potential water-quality impacts on nearby surface-water resources, including Rye Patch Reservoir and the Humboldt River; (2) potential impacts on municipal water resources of Winnemucca, Nevada; (3) locations and altitudes of aquifers; (4) how long it will take waste seepage from the site to contaminate local aquifers; and (5) the direction and distance that contaminated groundwater would travel at 95 and 190 years. This evaluation was based on review of existing data and information. Desert Valley is tributary to the Black Rock Desert via the Quinn River in northern Desert Valley. The Humboldt River and Rye Patch Reservoir would not be affected by surface releases from the proposed Jungo landfill site because they are in the Humboldt basin. Winnemucca, on the Humboldt River, is 30 miles east of the Jungo landfill site and in the Humboldt basin. Groundwater-flow directions indicate that subsurface flow near the proposed Jungo landfill site is toward the south-southwest. Therefore, municipal water resources of Winnemucca would not be affected by surface or subsurface releases from the proposed Jungo landfill site. Basin-fill aquifers underlie the 680-square-mile valley floor in Desert Valley. Altitudes around the proposed Jungo landfill site range from 4,162 to 4,175 feet. Depth to groundwater is fairly shallow in southern Desert Valley and is about 60 feet below land surface at the proposed Jungo landfill site. A groundwater divide exists about 7 miles north of the proposed Jungo landfill site. Groundwater north of the divide flows north towards the Quinn River. South of the divide and near the proposed Jungo landfill site, groundwater flows in a south-southwesterly direction. Data are insufficient to determine whether groundwater eventually flows into Rye Patch Reservoir or other adjacent valleys. Estimates indicate that contaminants would travel about 0.02 mile and a maximum of 2.5 miles in 95 years and about 0.04 mile and a maximum of 5.0 miles in 190 years. The closest supply wells that could be impacted by contaminants are 5 to 6 miles downgradient and are used for industry, irrigation, and stock watering.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.; Environmental Science Division

In April 2008, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) conducted groundwater sampling for the analysis of volatile organic compounds (VOCs) in the existing network of monitoring points at Everest, Kansas (Argonne 2008). The objective of the 2008 investigation was to monitor the distribution of carbon tetrachloride contamination in groundwater previously identified in CCC/USDA site characterization and groundwater sampling studies at Everest in 2000-2006 (Argonne 2001, 2003, 2006a,b). The work at Everest is being undertaken on behalf of the CCC/USDA by Argonne National Laboratory, under the oversight of the Kansas Department of Health and Environment (KDHE).more » The findings of the 2008 investigation were as follows: (1) Measurements of groundwater levels obtained manually and through the use of automatic recorders demonstrated a consistent pattern of groundwater flow - and inferred contaminant migration - to the north-northwest from the former CCC/USDA facility toward the Nigh property, and then west-southwest from the Nigh property toward the intermittent creek that lies west of the former CCC/USDA facility and the Nigh property. (2) The range of concentrations and the areal distribution of carbon tetrachloride identified in the groundwater at Everest in April 2008 were generally consistent with previous results. The results of the 2008 sampling (reflecting the period from 2006 to 2008) and the earlier investigations at Everest (representing the period from 2000 to 2006) show that no significant downgradient extension of the carbon tetrachloride plume occurred from 2000 to 2008. (3) The slow contaminant migration indicated by the monitoring data is qualitatively consistent with the low groundwater flow rates in the Everest aquifer unit estimated previously on the basis of site-specific hydraulic testing (Argonne 2006a,b). (4) The April 2008 and earlier sampling results demonstrate that the limits of the plume have been effectively, identified by the existing network of monitoring points and have not changed significantly during the CCC/USDA investigation program. The carbon tetrachloride distribution within the plume has continued to evolve, however, with relatively constant or apparently decreasing contaminant levels at most sampling locations. In response to these findings, the KDHE requested that the CCC/USDA develop a plan for annual monitoring of the groundwater and surface water at Everest, to facilitate continued tracking of the carbon tetrachloride plume at this site (KDHE 2009a). A recommendation for annual sampling (for analyses of VOCs) of 16 existing groundwater monitoring points within and near the identified contaminant migration pathway and surface water sampling at 5 locations along the intermittent creek west (downgradient) of the identified plume was presented by the CCC/USDA (Appendix A) and approved by the KDHE (2009b) for implementation. The monitoring wells will be sampled according to the low-flow procedure, and sample preservation, shipping, and analysis activities will be consistent with previous work at Everest. The annual sampling will continue until identified conditions at the site indicate a technical justification for a change. This report summarizes the results of sampling and monitoring activities conducted at the Everest site since completion of the April 2008 groundwater sampling event (Argonne 2008). The investigations performed during the current review period (May 2008 to October 2009) were as follows: (1) With one exception, the KDHE-approved groundwater and surface water monitoring points were sampled on April 24-27, 2009. In this event, well PT1 was inadvertently sampled instead of the adjacent well MW04. This investigation represents the first groundwater and surface water sampling event performed under the current plan for annual monitoring approved by the KDHE. (2) Ongoing monitoring of the groundwater levels at Everest is performed with KDHE approval. The levels in selected monitoring wells are recorded continuously, by using downhole pressure sensors equipped with automatic data loggers, and periodically are also measured manually. Groundwater level data were recovered during the current review period on September 19, 2008, and on March 25, April 25-27, and October 20, 2009. (3) Argonne experience has demonstrated that the sampling and analysis (for VOCs) of native vegetation, and particularly tree tissues, often provides a sensitive indicator of possible carbon tetrachloride contamination in the surface water or shallow groundwater within the plant rooting zone. With the approval of the CCC/USDA, on August 28, 2009, samples of tree branch tissues were therefore collected for analyses at 18 locations along the intermittent creek west (downgradient) of the former CCC/USDA facility and the Nigh property.« less

Hydrostratigraphy, soil/sediment chemistry, and water quality, Potomac-Raritan-Magothy aquifer system, Puchack Well Field Superfund site and vicinity, Pennsauken Township, Camden County, New Jersey, 1997-2001

USGS Publications Warehouse

Barringer, Julia L.; Walker, Richard L.; Jacobsen, Eric; Jankowski, Pamela

2010-01-01

Drinking-water supplies from the Potomac-Raritan-Magothy aquifer system at the Puchack well field in Pennsauken Township, Camden County, New Jersey, have been contaminated by hexavalent chromium-the most toxic and mobile form-at concentrations exceeding the New Jersey maximum contaminant level of 100 micrograms per liter. Also, scattered but widespread instances of volatile organic compounds (primarily trichloroethylene) at concentrations that exceed their respective maximum contaminant levels in the area's ground water have been reported. Because inorganic and organic contaminants are present in the ground water underlying the Puchack well field, no water from there has been withdrawn for public supply since 1998, when the U.S. Environmental Protection Agency (USEPA) added the area that contains the Puchack well field to the National Priorities List. As part of the USEPA's investigation of the Puchack Well Field Superfund site, the U.S. Geological Survey (USGS) conducted a study during 1997-2001 to (1) refine previous interpretations of the hydrostratigraphic framework, hydraulic gradients, and local directions of ground-water flow; (2) describe the chemistry of soils and saturated aquifer sediments; and (3) document the quality of ground water in the Potomac-Raritan-Magothy aquifer system in the area. The four major water-bearing units of the Potomac-Raritan-Magothy aquifer system-the Upper aquifer (mostly unsaturated in the study area), the Middle aquifer, the Intermediate Sand (a local but important unit), and the Lower aquifer-are separated by confining units. The confining units contain areas of cut and fill, resulting in permeable zones that permit water to pass through them. Pumping from the Puchack well field during the past 3 decades resulted in downward hydraulic gradients that moved contaminants into the Lower aquifer, in which the production wells are finished, and caused ground water to flow northeast, locally. A comparison of current (1997-2001) water levels near the site of the former pumping center with data from previous investigations indicates that, since pumping at the Puchack well field ceased, the dominant local ground-water flow direction is to the southeast, aligned with regional flow. Chromium concentrations were highest (8,010 micrograms per liter in 2000-01) in water from the Middle aquifer immediately downgradient from a possible source; the extent of this chromium plume is unknown but appears to be small. A second, unrelated, localized chromium plume also was identified in the Middle aquifer. The Intermediate Sand was found to contain an areally extensive plume of chromium-contaminated water, with concentrations up to 6,310 micrograms per liter in 2000-01, and another plume of about the same size, with concentrations up to 4,810 micrograms per liter in 2000-01, was identified in the Lower aquifer. The previous USGS investigation indicated the approximate extent of the combined plumes; the current delineation indicates that their locations have shifted slightly to the southeast since 1998. Concentrations of chromium in ground water decreased at some well locations by as much as 60 percent between sampling rounds in 1997-98 and 1999-2001. The decrease in chromium concentration at a given well could be the result of the chemical reduction of hexavalent chromium and precipitation of the resulting trivalent chromium, the sorption of hexavalent chromium to aquifer materials, or the physical movement of the plumes. Available data indicate that all three processes likely have affected concentrations. The distribution of hexavalent and total chromium in the soils and sediments of a possible source area indicates that some hexavalent chromium has undergone chemical reduction in the soils, but the degree to which this process takes place in the aquifer currently is not known. Nor is it known whether contaminated soils continue to contribute chromium to the aquifer system. Contamination by vola

Linking AS, SE, V, and MN Behavior to Natural Biostimulated Uranium Cycling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keimowitz, Alison; Ranville, James; Mailloux, Brian

The project “Linking As, Se, V, and Mn behavior to Natural and Biostimulated Uranium Cycling” successfully investigated Arsenic cycling the Rifle Colorado IFRC. This project trained undergraduate and graduate students at the Colorado School of Mines, Vassar College, and Barnard College. This resulted in both undergraduate theses and a PhD thesis and multiple publications. The science was highly successful and we were able to test the main hypotheses. We have shown that (H1) under reducing conditions that promote uranium immobilization arsenic is readily mobilized, that (H2) thioarsenic species are abundant during this mobilization, and (H3) we have examined arsenic mobilizationmore » for site sediment. At the Rifle IFRC Acetate was added during experiments to immobilize Uranium. These experiments successfully immobilized uranium but unfortunately would mobilize arsenic. We developed robust sampling and analysis methods for thioarsenic species. We showed that the mobilization occurred under sulfate reducing conditions and the majority of the arsenic was in the form of thioarsenic species. Previous studies had predicted the presence of thioarsenic species but this study used robust field and laboratory methods to quantitatively determine the presence of thioarsenic species. During stimulation in wells with high arsenic the primary species were trithioarsenate and dithioarsenate. In wells with low levels of arsenic release thioarsenates were absent or minor components. Fortunately after the injection of acetate ended the aquifer would become less reducing and the arsenic concentrations would decrease to pre-injection levels. In aquifers where organic carbon is being added as a remedial method or as a contaminant the transient mobility of arsenic during sulfidogenesis should be considered especially in sulfate rich aquifers as this could impact downgradient water quality.« less

Cation exchange in a glacial till drumlin at a road salt storage facility

NASA Astrophysics Data System (ADS)

Ostendorf, David W.; Xing, Baoshan; Kallergis, Niki

2009-05-01

We use laboratory and field data to calibrate existing geochemical and transport models of cation exchange induced by contamination of an unconfined aquifer at a road salt storage facility built upon a glacial till drumlin in eastern Massachusetts. A Gaines and Thomas selectivity coefficient K models the equilibrium sodium and divalent cation distribution in the groundwater and solid matrix, while an existing method of characteristics model describes the advective transport of total dissolved cations and sorbed sodium. Laboratory isotherms of split spoon soil samples from the drumlin calibrate K with an average value of 0.0048 (L/g) 1/2 for a measured cation exchange capacity of 0.057 meq/g dry soil. Ten years of monitoring well data document groundwater flow and the advection of conservative chloride due to outdoor storage and handling of road salt at the site. The monitoring well cation data and retarded transport model offer an independent K calibration of 0.0040 to 0.0047 (L/g) 1/2: the consistency of the field and laboratory selectivity coefficient calibrations endorse this application of the Gaines and Thomas and method of characteristics models. The advancing deicing agent plume releases divalent cations from the till into the groundwater, so that monitoring well samples do not reflect the chemical composition of the road salt. In this regard, dissolved divalent cation milliequivalent concentrations are as high as 80% of the total dissolved cationic concentrations in the salt contaminated monitoring well samples, far greater than their 2.5% level in the road salt stored at the site. Cation exchange can thus obscure attempts to hindcast stored road salt sodium water table concentration from monitoring well sample stoichiometry, or to predict sodium impacts on groundwater or receiving stream quality downgradient of the well.

Cation exchange in a glacial till drumlin at a road salt storage facility.

PubMed

Ostendorf, David W; Xing, Baoshan; Kallergis, Niki

2009-05-12

We use laboratory and field data to calibrate existing geochemical and transport models of cation exchange induced by contamination of an unconfined aquifer at a road salt storage facility built upon a glacial till drumlin in eastern Massachusetts. A Gaines and Thomas selectivity coefficient K models the equilibrium sodium and divalent cation distribution in the groundwater and solid matrix, while an existing method of characteristics model describes the advective transport of total dissolved cations and sorbed sodium. Laboratory isotherms of split spoon soil samples from the drumlin calibrate K with an average value of 0.0048 (L/g)(1/2) for a measured cation exchange capacity of 0.057 meq/g dry soil. Ten years of monitoring well data document groundwater flow and the advection of conservative chloride due to outdoor storage and handling of road salt at the site. The monitoring well cation data and retarded transport model offer an independent K calibration of 0.0040 to 0.0047 (L/g)(1/2): the consistency of the field and laboratory selectivity coefficient calibrations endorse this application of the Gaines and Thomas and method of characteristics models. The advancing deicing agent plume releases divalent cations from the till into the groundwater, so that monitoring well samples do not reflect the chemical composition of the road salt. In this regard, dissolved divalent cation milliequivalent concentrations are as high as 80% of the total dissolved cationic concentrations in the salt contaminated monitoring well samples, far greater than their 2.5% level in the road salt stored at the site. Cation exchange can thus obscure attempts to hindcast stored road salt sodium water table concentration from monitoring well sample stoichiometry, or to predict sodium impacts on groundwater or receiving stream quality downgradient of the well.

Hydrogeologic Characteristics of the St. Croix River Basin, Minnesota and Wisconsin: Implications for the Susceptibility of Ground Water to Potential Contamination

USGS Publications Warehouse

Juckem, Paul F.

2007-01-01

Population growth in the St. Croix River Basin in Minnesota and Wisconsin has intensified concerns of county resource managers and the National Park Service, which is charged with protecting the St. Croix National Scenic Riverway, about the potential for ground-water contamination in the basin. This report describes a previously developed method that was adapted to illustrate potential ground-water-contamination susceptibility in the St. Croix River Basin. The report also gives an estimate of ground-water-residence time and surface-water/ground-water interaction as related to natural attenuation and movement of contaminants in five tributary basins. A ground-water-contamination-susceptibility map was adapted from a state-wide map of Wisconsin to the St. Croix River Basin by use of well-driller construction records and regional maps of aquifer properties in Minnesota and Wisconsin. Measures of various subsurface properties were combined to generate a spatial index of susceptibility. The subjective index method developed for the State of Wisconsin by Schmidt (1987) was not derived from analyses of water-quality data or physical processes. Nonetheless, it was adapted for this report to furnish a seamless map across state boundaries that would be familiar to many resource managers. Following this method, areas most susceptible to contamination appear to have coarse-grained sediments (sands or gravels) and shallow water tables or are underlain by carbonate-bedrock aquifers. The least susceptible areas appear to have fine-grained sediments and deep water tables. If an aquifer becomes contaminated, the ground-water-residence time can affect potential natural attenuation along the ground-water-flow path. Mean basin ground-water-residence times were computed for the Apple, Kettle, Kinnickinnic, Snake and Sunrise River Basins, which are tributary basins to the St. Croix Basin, by use of average aquifer properties of saturated thickness, porosity, and recharge rates. The Apple River Basin had the shortest mean ground-water-residence times (20-120 years), owing largely to the moderate saturated thickness and high recharge rate in the basin. The Kinnickinnic and Sunrise River Basins had the longest mean residence times (60-350 and 70-390 years, respectively) chiefly because of the relatively large saturated thickness of the basins. Owing to limitations of the residence-time calculations, actual ground-water-residence times will vary around the mean values within each basin and may range from days or weeks in karst carbonate aquifers to millennia in deep confined sandstone aquifers. Areas of relatively short residence time (less than the median residence time in each basin) were identified by use of ground-water-flow models for each of the five tributary basins. Results of simulations show that these areas, in which contaminants may have relatively less time for natural attenuation along the short flow paths, generally occur near streams and rivers where ground water discharges to the surface. Finally, the ground-water-flow models were used to simulate ground-water/surface-water interaction in the five tributary basins. Results of simulations show that some lakes and reservoirs leak surface water into the ground-water-flow system on their downgradient side, where the surface-water outflow has been restricted by a dam or a naturally constricted outlet. These locations are noteworthy because contaminated surface waters could potentially enter the ground-water-flow system at these locations.

Estimates of groundwater age from till and carbonate bedrock hydrogeologic units at Jefferson Proving Ground, Southeastern Indiana, 2007-08

USGS Publications Warehouse

Buszka, Paul M.; Lampe, David C.; Egler, Amanda L.

2010-01-01

During 2007-08, the U.S. Geological Survey, in cooperation with the U.S. Department of the Army, conducted a study to evaluate the relative age of groundwater in Pre-Wisconsinan till and underlying shallow and deep carbonate bedrock units in and near an area at Jefferson Proving Ground (JPG), southeastern Indiana, which was used during 1984-94 to test fire depleted uranium (DU) penetrators. The shallow carbonate unit includes about the upper 40 feet of bedrock below the bedrock-till surface; the deeper carbonate unit includes wells completed at greater depth. Samples collected during April 2008 from 15 wells were analyzed for field water-quality parameters, dissolved gases, tritium, and chlorofluorocarbon (CFC) compounds; samples from 14 additional wells were analyzed for tritium only. Water-level gradients in the Pre-Wisconsinan till and the shallow carbonate unit were from topographically higher areas toward Big Creek and Middle Fork Creek, and their tributaries. Vertical gradients were strongly downward from the shallow carbonate unit toward the deep carbonate unit at 3 of 4 paired wells where water levels recovered after development; indicating the general lack of flow between the two units. The lack of post development recovery of water levels at 4 other wells in the deep carbonate unit indicate that parts of that unit have no appreciable permeability. CFC and tritium-based age dates of Pre-Wisconsinan till groundwater are consistent with infiltration of younger (typically post-1960 age) recharge that 'mixes' with older recharge from less permeable or less interconnected strata. Part of the recharge to three till wells dated from the early to mid-1980s (JPG-DU-03O, JPG-DU-09O, and JPG-DU-10O). Age dates of young recharge in water from two till wells predated 1980 (JPG-DU-04O and JPG-DU-06O). Tritium-based age dates of water from seven other till wells indicated post-1972 age recharge. Most wells in the Pre-Wisconsinan till have the potential to produce groundwater that partially was recharged during or after DU penetrator testing; their water quality can indicate the presence of DU-related contaminants. The shallow carbonate unit near Big Creek is a karst flow system that may be recharged in part from areas with smaller thicknesses of overlying till or through more permeable parts of the till. This is indicated by CFC- and tritium-based piston-flow (non-mixing) model age dates of early-1980s for water from JPG-DU-02I, similar tritium-based ages of water produced from nearby wells MW-5 and MW-11, and cave development along the creek. The CFC and tritium-based age dates indicate that water samples from JPG-DU-01I and JPG-DU-03I were best described as mixtures of post-1984 modern recharge and submodern (1953 or older) recharge. These five wells produced groundwater that was recharged, at least partially, during or after DU-penetrator testing and are within or downgradient from the DU Impact Area with respect to groundwater flow directions inferred from water-level contours. Wells with groundwater age dates that are near to or after the onset (1984) of DU penetrator testing and that have a plausible connection to a contaminant source can be used to indicate the presence or absence of contaminants from DU penetrator or DU-related corrosion products in groundwater. Groundwater-age dates indicate that the ages of recharge sampled from shallow carbonate unit wells JPG-DU-04I, JPG-DU-05I, JPG-DU-06I, JPG-DU-09I, and JPG-DU-10D in easternmost (upgradient) and southernmost wells in the shallow carbonate unit are submodern (1953 or older) and predate the DU testing by at least 30 or more years. Water-quality data from these five wells are not likely to represent effects from DU-projectile testing or corrosion for years. Well JPG-DU-09D in the deep carbonate unit produced groundwater samples with a submodern (1953 or older) age date. The slow recovery of water levels in most wells in the deep carbonate unit is consis

Using an implicitly-coupled hydrologic and river-operations models to investigate the trade-offs of artificial recharge in agricultural areas

NASA Astrophysics Data System (ADS)

Morway, E. D.; Niswonger, R. G.; Triana, E.

2016-12-01

In irrigated agricultural regions supplied by both surface-water and groundwater, increased reliance on groundwater during sustained drought leads to long-term water table drawdown and subsequent surface-water losses. This, in turn, may threaten the sustainability of the irrigation project. To help offset groundwater resource losses and restore water supply reliability, an alternative management strategy commonly referred to as managed aquifer recharge (MAR) in agricultural regions helps mitigate long-term aquifer drawdown and provides additional water for subsequent withdraw. Sources of MAR in this investigation are limited to late winter runoff in years with above average precipitation (i.e., above average snowpack). However, where winter MAR results in an elevated water table, non-beneficial consumptive use may increase from evapotranspiration in adjacent and down-gradient fallow and naturally vegetated lands. To rigorously explore this trade-off, the recently published MODSIM-MODFLOW model was applied to quantify both the benefits and unintended consequences of MAR. MODSIM-MODFLOW is a generalized modeling tool capable of exploring the effects of altered river operations within an integrated groundwater and surface-water (GW-SW) model. Thus, the MODSIM-MODFLOW model provides a modeling platform capable of simulating MAR in amounts and duration consistent with other senior water rights in the river system (e.g., minimum in-stream flow requirements). Increases in non-beneficial consumptive use resulting from winter MAR are evaluated for a hypothetical model patterned after alluvial aquifers common in arid and semi-arid areas of the western United States. Study results highlight (1) the benefit of an implicitly-coupled river operations and hydrologic modeling tool, (2) the balance between winter MAR and the potential increase in non-beneficial consumptive use, and (3) conditions where MAR may or may not be an appropriate management option, such as the availability of surface-water storage.

Digital-transport model study of Diisopropylmethylphosphonate (DIMP) ground-water contamination at the Rocky Mountain Arsenal, Colorado

USGS Publications Warehouse

Warner, James W.

1979-01-01

Diisopropylmethylphosphonate (DIMP) is an organic compound produced as a by-product of the manufacture and detoxification of GB nerve gas. Ground-water contamination by DIMP from the disposal of wastes into unlined surface ponds at the Rocky Mountain Arsenal occurred from 1952 to 1956. A digital-transport model was used to determine the effects on ground-water movement and on DIMP concentrations in the ground water of a bentonite barrier in the aquifer near the northern boundary of the arsenal. The transport model is based on an iterative-alternating-direction-implicit mathematical solution of the ground-water-flow equation coupled with a method-of-characteristics solution of the solute-transport equation. The model assumes conservative (nonreactive) transient transport of DIMP and steady-state ground-water flow. In the model simulations, a bentonite barrier was assumed that was impermeable and penetrated the entire saturated thickness of the aquifer. Ground water intercepted by the barrier was assumed to be pumped by wells located south (upgradient) of the barrier, to be treated to remove DIMP, and to be recharged by pits or wells to the aquifer north (downgradient) of the barrier. The amount of DIMP transported across the northern boundary of the arsenal was substantially reduced by a ground-water-barrier system of this type. For a 1,500-foot-long bentonite barrier located along the northern boundary of the arsenal near D Street, about 50 percent of the DIMP that would otherwise cross the boundary would be intercepted by the barrier. This barrier configuration and location were proposed by the U.S. Army. Of the ground water with DIMP concentrations greater than 500 micrograms per liter, the safe DIMP-concentration level determined by the U.S. Army, about 72 percent would be intercepted by the barrier system. The amount of DIMP underflow intercepted may be increased to 65 percent by doubling the pumpage, or to 73 percent by doubling the length of the barrier. (Kosco-USGS)

A progress report on results of test drilling and ground-water investigations of the Snake Plain aquifer, southeastern Idaho: Part 1: Mud Lake Region, 1969-70 and Part 2: Observation Wells South of Arco and West of Aberdeen

USGS Publications Warehouse

Crosthwaite, E.G.

1973-01-01

The results of drilling test holes to depths of approximately 1,000 feet in the Mud Lake region show that a large part of the region is underlain by both sedimentary deposits and basalt flows. At some locations, predominantly sedimentary deposits were penetrated; at others, basalt flows predominated. The so-called Mud Lake-Market Lake barrier denotes a change in geology. From the vicinity of the barrier area, as described by Stearns, Crandall, and Steward (1938, p. 111), up the water-table gradient for at least a few tens of miles, the saturated geologic section consists predominantly of beds of sediments that are intercalated with numerous basalt flows. Downgradient from the barrier, sedimentary deposits are not common and practically all the water-bearing formations are basalt, at least to the depths explored so far. Thus, the barrier is a transition zone from a sedimentary-basaltic sequence to a basaltic sequence. The sedimentary-basaltic sequence forms a complex hydrologic system in which water occurs under water-table conditions in the upper few tens of feet of saturated material and under artesian conditions in the deeper material in the southwest part of the region. The well data indicate that southwest of the barrier, artesian pressures are not significant. Southwest of the barrier, few sedimentary deposits occur in the basalt section and, as described by Mundorff, Crosthwaite, and Kilburn (1964). ground water occurs in a manner typical of the Snake Plain aquifer. In several wells, artesian pressures are higher in the deeper formations than in the shallower ones, but the reverse was found in a few wells. The available data are not adequate to describe the water-bearing characteristics of the artesian aquifer nor the effects that pumping in one zone would have on adjacent zones. The water-table aquifer yields large quantities of water to irrigation wells.

Water-level variations and their effects on tree growth and mortality and on the biogeochemical system at the phytoremediation demonstration site in Fort Worth, Texas, 1996-2003

USGS Publications Warehouse

Braun, Christopher L.; Eberts, Sandra M.; Jones, Sonya A.; Harvey, Gregory J.

2004-01-01

In 1996, a field-scale phytoremediation demonstration project was initiated and managed by the U.S. Air Force at a site in western Fort Worth, Texas, using a plantation of 1-year-old stems harvested from branches of eastern cottonwoods during the dormant season (whips) and a plantation of 1-year-old eastern cottonwood seedlings (calipers). The primary objective of the demonstration project was to determine the effectiveness of eastern cottonwoods at reducing the mass of dissolved trichloroethene transported within an alluvial aquifer. The U.S. Geological Survey conducted a study, in cooperation with the U.S. Air Force, to determine water-level variations and their effects on tree growth and mortality and on the biogeochemical system at the phytoremediation site. As part of the study, water-level and water-quality data were collected throughout the duration of the project. This report presents water-level variations at periodic sampling events; data from August 1996 to January 2003 are presented in this report. Water levels are affected by aquifer properties, precipitation, drawdown attributable to the trees in the study area, and irrigation. This report also evaluates the effects of ground-water depth on tree growth and mortality rates and on the biogeochemical system including subsurface oxidation-reduction processes. Overall, both whips and calipers showed a substantial increase in height, canopy diameter, and trunk diameter over the first 3 years of the study. By the fifth growing season (September 2000), the height of the calipers varied predictably with height decreasing with increasing depth to ground water. Percent mortality was relatively constant at about 25 percent in the whip plantation in January 2003 where ground-water levels were less than 10 feet below land surface during the drought in September 2000. The mortality rate increased where the ground-water levels were greater than 10 feet below land surface and approached 90 percent where ground-water levels were between 12 and 13 feet. A decrease in molar ratio of trichloroethene to cis-dichloroethene was measured in ground water within and downgradient from the planted area over time. Decreases in these ratios appeared to be related to ground-water depth. The molar ratios of trichloroethene to cis-dichloroethene during the third growing season were relatively constant, between 3.0 and 4.0, in samples collected from wells across the site. By the end of the fifth growing season the lowest ratio was measured in areas where ground-water depth was less than 10 feet below land surface; these same areas had the lowest dissolved oxygen concentrations (0.93 to 1.7 milligrams per liter) and the highest dissolved organic carbon concentrations (1.6 to 1.8 milligrams per liter). This indicates that between the third and fifth growing seasons, a labile fraction of dissolved organic carbon had been introduced into the aquifer by the planted trees that was capable of stimulating reductive dechlorination of trichloroethene.

Aquifer Storage Recovery (ASR) of chlorinated municipal drinking water in a confined aquifer

USGS Publications Warehouse

Izbicki, John A.; Petersen, Christen E.; Glotzbach, Kenneth J.; Metzger, Loren F.; Christensen, Allen H.; Smith, Gregory A.; O'Leary, David R.; Fram, Miranda S.; Joseph, Trevor; Shannon, Heather

2010-01-01

About 1.02 x 106 m3 of chlorinated municipal drinking water was injected into a confined aquifer, 94-137 m below Roseville, California, between December 2005 and April 2006. The water was stored in the aquifer for 438 days, and 2.64 x 106 m3 of water were extracted between July 2007 and February 2008. On the basis of Cl data, 35% of the injected water was recovered and 65% of the injected water and associated disinfection by-products (DBPs) remained in the aquifer at the end of extraction. About 46.3 kg of total trihalomethanes (TTHM) entered the aquifer with the injected water and 37.6 kg of TTHM were extracted. As much as 44 kg of TTHMs remained in the aquifer at the end of extraction because of incomplete recovery of injected water and formation of THMs within the aquifer by reactions with freechlorine in the injected water. Well-bore velocity log data collected from the Aquifer Storage Recovery (ASR) well show as much as 60% of the injected water entered the aquifer through a 9 m thick, high-permeability layer within the confined aquifer near the top of the screened interval. Model simulations of ground-water flow near the ASR well indicate that (1) aquifer heterogeneity allowed injected water to move rapidly through the aquifer to nearby monitoring wells, (2) aquifer heterogeneity caused injected water to move further than expected assuming uniform aquifer properties, and (3) physical clogging of high-permeability layers is the probable cause for the observed change in the distribution of borehole flow. Aquifer heterogeneity also enhanced mixing of native anoxic ground water with oxic injected water, promoting removal of THMs primarily through sorption. A 3 to 4-fold reduction in TTHM concentrations was observed in the furthest monitoring well 427 m downgradient from the ASR well, and similar magnitude reductions were observed in depth-dependent water samples collected from the upper part of the screened interval in the ASR well near the end of the extraction phase. Haloacetic acids (HAAs) were completely sorbed or degraded within 10 months of injection.

Monitoring the effect of poplar trees on petroleum-hydrocarbon and chlorinated-solvent contaminated ground water

USGS Publications Warehouse

Landmeyer, James E.

2001-01-01

At contaminated groundwater sites, poplar trees can be used to affect ground-water levels, flow directions, and ultimately total groundwater and contaminant flux to areas downgradient of the trees. The magnitude of the hydrologic changes can be monitored using fundamental concepts of groundwater hydrology, in addition to plant physiology-based approaches, and can be viewed as being almost independent of the contaminant released. The affect of poplar trees on the fate of groundwater contaminants, however, is contaminant dependent. Some petroleum hydrocarbons or chlorinated solvents may be mineralized or transformed to innocuous compounds by rhizospheric bacteria associated with the tree roots, mineralized or transformed by plant tissues in the transpiration stream or leaves after uptake, or passively volatilized and rapidly dispersed or oxidized in the atmosphere. These processes also can be monitored using a combination of physiological- or geochemical-based field or laboratory approaches. When combined, such hydrologic and contaminant monitoring approaches can result in a more accurate assessment of the use of poplar trees to meet regulatory goals at contaminated groundwater sites, verify that these goals continue to be met in the future, and ultimately lead to a consensus on how the performance of plant-based remedial strategies (phytoremediation) is to be assessed.

USE OF TRACER INJECTION EXPERIMENTS TO QUANTIFY NITRATE LOSS IN TWO ADJACENT WETLAND STREAMS DRAINING AN AGRICULTURAL FIELD IN THE GEORGIA PIEDMONT

EPA Science Inventory

This study investigated the extent to which nitrate was removed from and/or stored in a small wetland depression downgradient of a 10-ha cattle rotational grazing pasture and a 2.5-ha cropped catchment at the USDA-ARS J. Phil Campbell Sr. Natural Resource Conservation Center in W...

Enhanced Attenuation: Chlorinated Organics

DTIC Science & Technology

2008-04-01

attenuation capacity of the aquifer downgradient from the source (e.g., permeable reactive barriers or phytoremediation ) Selection of EA remedies should be...ranging from very aggressive source destruction and removal methods to less energy-intensive methods, such as phytoremediation . In many cases, it...plumes that include chlorinated organics. The flux of organic-rich leachate to underlying aquifers can create favorable conditions for the natural

A DOM Odyssey: The Tale of Molecular Transformations in an Aquifer near Bemidji, MN

NASA Astrophysics Data System (ADS)

Podgorski, D. C.; Zito, P.; Smith, D. F.; Cao, X.; Schmidt-Rohr, K.; Wagner, S.; Stubbins, A.; Aiken, G.; Cozzarelli, I.; Bekins, B. A.; Spencer, R. G.

2017-12-01

Analytical methods including fluorescence spectroscopy, NMR spectroscopy, and ultrahigh resolution mass spectrometry have significantly advanced the understanding of compositional controls on dissolved organic matter (DOM) processing and fate. Yet, we still heavily rely on extrapolation of chemical changes identified at the edges of the compositional continuum (i.e., endmembers) to assess DOM reactivity and stability. While extrapolation of chemical transformations is useful for determining relative changes in DOM composition, a comprehensive understanding of the underlying core structures and composition is required to develop advanced biogeochemical models. Studying DOM from natural systems is complicated by many variables associated with an open system including input from multiple sources, simultaneous photo-alteration and microbial processing, and obtaining samples that cover high spatial and temporal resolution. A 38-year biodegradation study at the National Crude Oil Spill Research site near Bemidji, MN provides a unique opportunity to monitor DOM in a relatively closed system. An extensively characterized 1 m thick oil body is confined to a 25 x 75 m2 area at the water table in the aquifer. Oxidized metabolites partition from the oil into the underlying aquifer increase the DOC concentration to > 100 ppm from < 2 ppm up-gradient from the oil body. This newly produced DOM is comprised of aliphatic compounds with high H/C, low O/C and blue-shifted fluorescence, similar in composition to permafrost- and algal-derived DOM. The aliphatic DOM is transported laterally from the oil pool by groundwater, creating a plume that ultimately discharges into the Unnamed Lake 325 m downgradient. More than 10 years later and hundreds of meters downgradient from the oil body, the DOC concentration has decreased to 3-5 ppm and the DOM is compositionally non-distinct. Microbes have left behind degradation products and selectively preserved compounds that exhibit red-shifted fluorescence and molecular formulas with O/C and H/C similar to those associated with the `island of stability'. Samples collected spatially from the DOM plume between these two endmembers provide sufficient temporal resolution to model both DOC concentration and DOM composition as a result of biodegradation.

Fate of MTBE relative to benzene in a gasoline-contaminated aquifer (1993-98):

USGS Publications Warehouse

Landmeyer, James E.; Chapelle, Francis H.; Bradley, Paul M.; Pankow, James F.; Church, Clinton D.; Tratnyek, Paul G.

1998-01-01

Methyl tert-butyl ether (MTBE) and benzene have been measured since 1993 in a shallow, sandy aquifer contaminated by a mid-1980s release of gasoline containing fuel oxygenates. In wells downgradient of the release area, MTBK was detected before benzene, reflecting a chromatographic-like separation of these compounds in the direction of ground water flow. Higher concentrations of MTBE and benzene were measured in the deeper sampling ports of multilevel sampling wells located near the release area, and also up to 10 feet (3 m) below the water table surface in nested wells located farther from the release area. This distribution of higher concentrations at depth is caused by recharge events that deflect originally horizontal ground water flowlines. In the laboratory, microcosms containing aquifer material incubated with uniformly labeled 14C-MTBE under aerobic and anaerobic. Fe(III)-reducing conditions indicated a low but measurable biodegradation potential (<3%14C-MTBW as 14CO2) after a seven-month incubation period, Tert-butyl alcohol (TBA), a proposed microbial-MTBE transformation intermediate, was detected in MTBE-contaminated wells, but TBA was also measured in unsaturated release area sediments. This suggests that TBA may have been present in the original fuel spilled and does not necessarily reflect microbial degradation of MTBE. Combined, these data suggest that milligram per liter to microgram per liter decreases in MTBE concentrations relative to benzene are caused by the natural attenuation processes of dilution and dispersion with less-contaminated ground water in the direction of flow rather than biodegradation at this point source gasoline release site.

Progression of natural attenuation processes at a crude oil spill site: II. Controls on spatial distribution of microbial populations

NASA Astrophysics Data System (ADS)

Bekins, Barbara A.; Cozzarelli, Isabelle M.; Godsy, E. Michael; Warren, Ean; Essaid, Hedeff I.; Tuccillo, Mary Ellen

2001-12-01

A multidisciplinary study of a crude-oil contaminated aquifer shows that the distribution of microbial physiologic types is strongly controlled by the aquifer properties and crude oil location. The microbial populations of four physiologic types were analyzed together with permeability, pore-water chemistry, nonaqueous oil content, and extractable sediment iron. Microbial data from three vertical profiles through the anaerobic portion of the contaminated aquifer clearly show areas that have progressed from iron-reduction to methanogenesis. These locations contain lower numbers of iron reducers, and increased numbers of fermenters with detectable methanogens. Methanogenic conditions exist both in the area contaminated by nonaqueous oil and also below the oil where high hydrocarbon concentrations correspond to local increases in aquifer permeability. The results indicate that high contaminant flux either from local dissolution or by advective transport plays a key role in determining which areas first become methanogenic. Other factors besides flux that are important include the sediment Fe(II) content and proximity to the water table. In locations near a seasonally oscillating water table, methanogenic conditions exist only below the lowest typical water table elevation. During 20 years since the oil spill occurred, a laterally continuous methanogenic zone has developed along a narrow horizon extending from the source area to 50-60 m downgradient. A companion paper [J. Contam. Hydrol. 53, 369-386] documents how the growth of the methanogenic zone results in expansion of the aquifer volume contaminated with the highest concentrations of benzene, toluene, ethylbenzene, and xylenes.

Geochemistry and hydrology of a calcareous fen within the Savage Fen wetlands complex, Minnesota, USA

USGS Publications Warehouse

Komor, S.C.

1994-01-01

Savage Fen is a wetlands complex at the base of north-facing bluffs in the Minnesota River Valley. The complex includes 27.8 hectares of calcareous fen that host rare calciphile plants whose populations are declining in Minnesota. Water and sediment compositions in the calcareous fen were studied to gain a better understanding of the hydrologie System that sustains the rare vegetation. Groundwater in the fen is a calcium-magnesium-bicarbonate type with circumneutral pH values. The groundwater composition is the resuit of interactions among water, dissolved and gaseous carbon species, carbonates, and ion exchangers. Shallow groundwater is distinguished from deep groundwater by smaller concentrations of chloride, sulfate, magnesium, and sodium, and larger concentrations of calcium, bicarbonate, hydrogen sulfide, and ammonium. Magnesian calcite is the prevalent carbonate in unconsolidated sedimentary fill beneath the fen and is an important source and sink for dissolved calcium, magnesium, and inorganic carbon. Calcite concentrations just below the water table are small because aerobic and anaerobic oxidation of organic matter increase the partial pressure of carbon dioxide (PCO2), decrease pH, and cause calcite to dissolve. Thick calcite accumulations just above the water table, in the root zone of calciphile plants, result from water table fluctuations and attendant changes in PCO2. Groundwater beneath Savage Fen recharges in lakes and ponds south of the fen and upwells to the surface within the fen. Water at the water table is a mixture of upwelling groundwater and water near the surface that flows downslope from higher elevations in the fen. Changes in oxygen and hydrogen isotope compositions of shallow groundwater indicate that the proportion of upwelling groundwater in shallow groundwater decreases downgradient in the calcareous fen. Encroachment of reed grasses into the calcareous fen may reflect human-caused disturbances in the recharge area.

Artificial recharge experiments on the Ship Creek alluvial fan, Anchorage, Alaska

USGS Publications Warehouse

Anderson, Gary S.

1977-01-01

During the summers of 1973 and 1974, water from Ship Creek was diverted at an average rate of approximately 6 cubic feet per second to an 11-acre recharge basin. Maximum sustained unit recharge for the basin was approximately 1.4 feet per day. Dur-ing 1975 a second basin of 8 acres was also used for recharge, and the total diversion rate was increased to as much as 30 cubic feet per second. The second basin was never completely filled, but the unit recharge rate was estimated to be at least four times as great as that in the first basin.During 1973 and 1974, when only one recharge basin was in operation, a maximum rise of 18 feet was observed in the ground-water table near the basin. In 1975, when both basins were being used, the maximum rise was 30 feet in the same area. During 1973 and 1974, the water-level rise was 12 and 8 feet in the unconfined and confined systems, respectively, at a point 4.400 feet downgradient from the basins; in 1975 the rise at the same point was 31 and 16 feet, respectively.It was originally believed that because of the location of the recharge ponds within the natural recharge zone of the area's confined aquifer system, the source of the major portion of Anchorage's public water supply, most of the artificially recharged water would enter that system. However, water-level data and changes in saturation conditions interpreted from borehole geophysical logs indicate that most of the recharged water remained in the unconfined aquifer. In addition, the potentiometric rise that was achieved in the confined aquifer during summer operation of the recharge basins was quickly dissipated when diversion stopped and the basins drained. Thus the benefits of recharge would not persist into late winter, the critical period of water availability in Anchorage, unless diversion to the basins could be continued until January or February.

Environmental occurrence and shallow ground water detection of the antibiotic monensin from dairy farms

USGS Publications Warehouse

Watanabe, N.; Harter, T.H.; Bergamaschi, B.A.

2008-01-01

Pharmaceuticals used in animal feeding operations have been detected in various environmental settings. There is a growing concern about the impact on terrestrial and aquatic organisms and the development of antibiotic-resistant strains of microorganisms. Pharmaceutical use in milking cows is relatively limited compared with other livestock operations, except for the ionophore monensin, which is given to lactating cows as a feed. By weight, monensin can be the most significant antibiotic used in a dairy farm. This study investigates the potential of monensin to move from dairy operations into the surrounding ground water. Using two dairy farms in California as study sites, we twice collected samples along the environmental pathway - from flush lanes, lagoon waters, and shallow ground water beneath the dairies and beneath its associated manured fields. Monensin concentrations were determined using solid-phase extraction and liquid chromatography-tandem mass spectrometry with positive electrospray ionization. Monensin was detected in all of the flush lane and lagoon water samples. Theoretical maximum concentration estimated from the actual dosing rate and the theoretical excretion rate assuming no attenuation was one order of magnitude greater than observed concentrations, suggesting significant attenuation in the manure collection and storage system. Monensin was also detected, at levels ranging from 0.04 to 0.39 ??g L-1, in some of the ground water samples underneath the production area of the dairy but not from the adjacent manured fields. Concentrations in ground water immediately downgradient of the lagoons were one to two orders of magnitude lower than the concentrations detected in lagoons, suggesting attenuation in the subsurface. The data suggest the possibility of monensin transport into shallow (2-5 m) alluvial ground water from dairy management units, including manure storage lagoons and freestalls occupied by heifers, lactating cows, and dry cows. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Inter-aquifer Dynamics in and Near a Confining Unit Window in Shelby County, Tennessee, USA

NASA Astrophysics Data System (ADS)

Gentry, R. W.; McKay, L. D.; Larsen, D.; Carmichael, J. K.; Solomon, D. K.; Thonnard, N.; Anderson, J. L.

2003-12-01

An interdisplinary research team is investigating the interaction between the surficial alluvial aquifer and the deeper confined Memphis aquifer in the Memphis area, Shelby County, Tennessee. Previous research has identified a window in the clay-rich, upper Claiborne confining unit that separates the two aquifers near a closed municipal landfill in east-central Shelby County, an area undergoing rapid urbanization. For this investigation, a combination of environmental tracers (tritium/helium-3), major and trace ion geochemistry, hydraulic response testing, measurement of hydraulic gradients, and groundwater flow modeling is being used to quantify recharge of young water from the alluvial aquifer through the window to the Memphis aquifer. The research will provide results to better understand how windows were formed and how they influence recharge and water quality in otherwise confined parts of the Memphis aquifer downdip of its outcrop/subcrop area. Examination of continuous core samples and geophysical logs from wells installed for the study using Rotasonic drilling methods confirmed the existence of a sand-dominated window that may be as much as 1 km in diameter in the upper Claiborne confining unit. The upper Claiborne confining unit is 15 to 20 m thick in most of the study area and is overlain by a 10 to 12 m thick alluvial aquifer. The window is interpreted to have formed as a result of depositional and incisional processes in an Eocene-age deltaic system. Hydraulic gradients of several feet exist vertically between the alluvial and Memphis aquifers within the window, indicating downward flow. Groundwater age-dates from tritium/helium-3 analyses indicate that groundwater in the window at the depth of the base of the surrounding confining unit (approximately 30 m) has an apparent age of 19.8 years, which confirms the occurrence of downward flow. Young groundwater age dates (less than 32 years) also were obtained from wells in the Memphis aquifer at confined sites downgradient of the window, suggesting that a plume of young water is spreading outwards from the window and mixing with the older Memphis aquifer water. Preliminary inverse modeling of the site using a genetic algorithm coupled with a central finite difference flow model indicates a probable steady-state downward flux of about 12,000 m3/d through the window. Collection and analysis of additional groundwater samples are planned to examine geochemical conditions in the confining unit and in the Memphis aquifer upgradient of the window. These analyses will aid in developing a final conceptual model and in subsequent numerical modeling of mixing of the young recharge water with the older Memphis aquifer water.

Quantity and location of groundwater recharge in the Sacramento Mountains, south-central New Mexico (USA), and their relation to the adjacent Roswell Artesian Basin

NASA Astrophysics Data System (ADS)

Rawling, Geoffrey C.; Newton, B. Talon

2016-06-01

The Sacramento Mountains and the adjacent Roswell Artesian Basin, in south-central New Mexico (USA), comprise a regional hydrologic system, wherein recharge in the mountains ultimately supplies water to the confined basin aquifer. Geologic, hydrologic, geochemical, and climatologic data were used to delineate the area of recharge in the southern Sacramento Mountains. The water-table fluctuation and chloride mass-balance methods were used to quantify recharge over a range of spatial and temporal scales. Extrapolation of the quantitative recharge estimates to the entire Sacramento Mountains region allowed comparison with previous recharge estimates for the northern Sacramento Mountains and the Roswell Artesian Basin. Recharge in the Sacramento Mountains is estimated to range from 159.86 × 106 to 209.42 × 106 m3/year. Both the location of recharge and range in estimates is consistent with previous work that suggests that ~75 % of the recharge to the confined aquifer in the Roswell Artesian Basin has moved downgradient through the Yeso Formation from distal recharge areas in the Sacramento Mountains. A smaller recharge component is derived from infiltration of streamflow beneath the major drainages that cross the Pecos Slope, but in the southern Sacramento Mountains much of this water is ultimately derived from spring discharge. Direct recharge across the Pecos Slope between the mountains and the confined basin aquifer is much smaller than either of the other two components.

Evaluation of Sources of Nitrate Beneath Food Processing Wastewater-Application Sites near Umatilla, Oregon

USGS Publications Warehouse

Frans, Lonna; Paulson, Anthony; Richerson, Phil; Striz, Elise; Black, Curt

2009-01-01

Water samples from wells were collected beneath and downgradient of two food-processing wastewater-application sites near Umatilla, Oregon. These samples were analyzed for nitrate stable isotopes, nutrients, major ions, and age-dating constituents to determine if nitrate-stable isotopes can be used to differentiate food-processing waste from other potential sources of nitrate. Major-ion data from each site were used to determine which samples were associated with the recharge of the food-processing wastewater. End-member mixing analysis was used to determine the relative amounts of each identified end member within the samples collected from the Terrace Farm site. The delta nitrogen-15 (delta 15N) of nitrate generally ranged between +2 and +9 parts per thousand and the delta oxygen-18 (delta 18O) of nitrate generally ranged between -2 and -7 parts per thousand. None of the samples that were determined to be associated with the wastewater were different from the samples that were not affected by the wastewater. The nitrate isotope values measured in this study are also characteristic of ammonium fertilizer, animal and human waste, and soil nitrate; therefore, it was not possible to differentiate between food-processing wastewater and the other nitrate sources. Values of delta 15N and delta 18O of nitrate provided no more information about the sources of nitrate in the Umatilla River basin than did a hydrologic and geochemical understanding of the ground-water system derived from interpreting water-level and major-ion chemistry data.

Sitewide monitoring at Agra, Kansas, June 2009.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.; Environmental Science Division

In 1985, carbon tetrachloride was discovered in the groundwater at Agra, Kansas, during routine sampling of public water supply wells. Two of Agra's four public water supply wells contained low but detectable levels of carbon tetrachloride; the concentrations in wells PWS-3 and PWS-4 exceeded the maximum contaminant level. These wells were removed from service in 1986, although they remain available for uses other than drinking water. Other public wells, outside the area of contamination, supply drinking water for the city of Agra. In 1987-2005, the Kansas Department of Health and Environment (KDHE) and the Commodity Credit Corporation of the U.S.more » Department of Agriculture (CCC/USDA) conducted investigations to delineate the contaminant plume and to identify source areas for the contamination - which results from the past use of grain fumigants containing carbon tetrachloride. Source areas were identified on the former CCC/USDA grain storage facility property and on the Producers Agricultural Marketing Association, Inc., property located to the south (Argonne 2006). The contaminant plume extends to the southeast, toward well PWS-3, from the identified source areas. Both the CCC/USDA and Pro-Ag Marketing are currently implementing KDHE-approved interim measures (IMs). To address the contamination identified on its former property, the CCC/USDA is implementing a source control IM consisting of large-diameter boreholes (LDBs) coupled with soil vapor extraction (SVE) and air sparging (AS). Pro-Ag Marketing plans to use groundwater extraction to address the downgradient plume. The CCC/USDA and Pro-Ag completed installation of the two interim measures in May 2009 and August 2009, respectively. The performance and assessments of the effectiveness of the IMs are being reported separately by the responsible entities. As part of the IM process, the KDHE (2008) requested the development of a joint sitewide groundwater monitoring plan to allow periodic assessment of the effectiveness of the separate IMs being implemented by the CCC/USDA and Pro-Ag, through monitoring of the level of contamination and the resulting change in both the extent and internal configuration of the downgradient plume. A Joint Work Plan for Sitewide Monitoring was developed by the CCC/USDA through its technical consultant, Argonne National Laboratory, and was reviewed, approved, and signed by Pro-Ag Marketing and subsequently submitted to the KDHE on May 12, 2009. The KDHE (2009a) provided comments on the Joint Work Plan on May 27, 2009, requesting submission of a revised version. To minimize delays, the KDHE allowed the CCC/USDA to proceed with the scheduled annual sampling proposed in the Joint Work Plan. The sampling was to be conducted according to the previously approved low-flow sampling methodology (Argonne 2009). Argonne conducted the first annual sampling event for the CCC/USDA on June 15-16, 2009. The finalized, signed version of the Joint Work Plan provided to the KDHE on November 9, 2009, is in Appendix A. Table 1.1 lists the monitoring and public water supply wells to be sampled under the Joint Work Plan, plus the wells being sampled to monitor the respective IMs. The entity responsible for each monitoring element is indicated, along with well completion dates and well registration numbers. The subject of this report is the initial sitewide groundwater sampling event that occurred on June 15-16, 2009, under the Joint Work Plan.« less

Occurrence and distribution of dissolved solids, selenium, and uranium in groundwater and surface water in the Arkansas River Basin from the headwaters to Coolidge, Kansas, 1970-2009

USGS Publications Warehouse

Miller, Lisa D.; Watts, Kenneth R.; Ortiz, Roderick F.; ,

2010-01-01

In 2007, the U.S. Geological Survey (USGS), in cooperation with City of Aurora, Colorado Springs Utilities, Colorado Water Conservation Board, Lower Arkansas Valley Water Conservancy District, Pueblo Board of Water Works, Southeastern Colorado Water Activity Enterprise, Southeastern Colorado Water Conservancy District, and Upper Arkansas Water Conservancy District began a retrospective evaluation to characterize the occurrence and distribution of dissolved-solids (DS), selenium, and uranium concentrations in groundwater and surface water in the Arkansas River Basin based on available water-quality data collected by several agencies. This report summarizes and characterizes available DS, dissolved-selenium, and dissolved-uranium concentrations in groundwater and surface water for 1970-2009 and describes DS, dissolved-selenium, and dissolved-uranium loads in surface water along the main-stem Arkansas River and selected tributary and diversion sites from the headwaters near Leadville, Colorado, to the USGS 07137500 Arkansas River near Coolidge, Kansas (Ark Coolidge), streamgage, a drainage area of 25,410 square miles. Dissolved-solids concentrations varied spatially in groundwater and surface water in the Arkansas River Basin. Dissolved-solids concentrations in groundwater from Quaternary alluvial, glacial drift, and wind-laid deposits (HSU 1) increased downgradient with median values of about 220 mg/L in the Upper Arkansas subbasin (Arkansas River Basin from the headwaters to Pueblo Reservoir) to about 3,400 mg/L in the Lower Arkansas subbasin (Arkansas River Basin from John Martin Reservoir to Ark Coolidge). Dissolved-solids concentrations in the Arkansas River also increased substantially in the downstream direction between the USGS 07086000 Arkansas River at Granite, Colorado (Ark Granite), and Ark Coolidge streamgages. Based on periodic data collected from 1976-2007, median DS concentrations in the Arkansas River ranged from about 64 mg/L at Ark Granite to about 4,060 mg/L at Ark Coolidge representing over a 6,000 percent increase in median DS concentrations. Temporal variations in specific conductance values (which are directly related to DS concentrations) and seasonal variations in DS concentrations and loads were investigated at selected sites in the Arkansas River from Ark Granite to Ark Coolidge. Analyses indicated that, for the most part, specific conductance values (surrogate for DS concentrations) have remained relatively constant or have decreased in the Arkansas River since about 1970. Dissolved-solids concentrations in the Arkansas River were higher during the nonirrigation season (November-February) than during the irrigation season (March-October). Average annual DS loads, however, were higher during the irrigation season than during the nonirrigation season. Average annual DS loads during the irrigation season were at least two times and as much as 23 times higher than average annual DS loads during the nonirrigation season with the largest differences occurring at sites located downstream from the two main-stem reservoirs at USGS 07099400 Arkansas River above Pueblo, Colorado (Ark Pueblo), (which is below Pueblo Reservoir) and USGS 07130500 Arkansas River below John Martin Reservoir, Colorado (Ark below JMR). View report for unabridged abstract.

Spatial and temporal distribution of specific conductance, boron, and phosphorus in a sewage-contaminated aquifer near Ashumet Pond, Cape Cod, Massachusetts

USGS Publications Warehouse

Bussey, K.W.; Walter, D.A.

1996-01-01

Spatial and temporal distributions of specific conductance, boron, and phosphorus were determined in a sewage-contaminated sand and gravel aquifer near Ashumet Pond, Cape Cod, Massachusetts. The source of contamination is secondarily treated sewage that has been discharged onto rapid- infiltration sand beds at the Massachusetts Military Reservation since 1936. Contaminated ground water containing as much as 2 milligrams per liter of dissolved phosphorus is discharging into Ashumet Pond, and there is concern that the continued discharge of phosphorus into the pond will accelerate eutrophication of the pond. Water-quality data collected from observation wells and multilevel samplers from June through July 1995 were used to delineate the spatial distributions of specific conductance, boron, and phosphorus. Temporal distributions were determined using sample-interval-weighted average concen- trations calculated from data collected in 1993, 1994, and 1995. Specific conductances were greater than 400 microsiemens per centimeter at 25C as far as 1,200 feet downgradient from the infiltration beds. Boron concentrations were greater than 400 micrograms per liter as far as 1,800 feet down- gradient from the beds and phosphorus concen- trations were greater than 3.0 milligrams per liter as far as 1,200 feet from the beds. Variability in distributions of specific conductance and boron concentrations is attributed to the history and distribution of sewage disposal onto the infiltration beds. The distribution of phosphorus concentrations also is related to the history and distribution of sewage disposal onto the beds but additional variability is caused by chemical interactions with the aquifer materials. Temporal changes in specific conductance and boron from 1993 to 1995 were negligible, except in the lower part of the plume (below an altitude of about 5 feet above sea level), where changes in weighted-average specific conductance were greater than 100 microsiemens per centimeter at 25C. Temporal changes in phosphorus generally were small except in the lower part of the plume, where weighted-average phosphorus concentrations decreased more than 1.3 milligrams per liter from 1993 to 1994. This decrease was accompanied by an increase in specific conductance. High concen- trations of phosphorus associated with low and moderate specific conductances possibly are the result of rapid phosphorus desorption in response to an influx of uncontaminated ground water. As a result of the cessation of sewage disposal in December 1995, clean, oxygenated water moving into contaminated parts of the aquifer may cause rapid desorption of sorbed phosphorus and temporarily result in high dissolved phosphorus concentrations in the aquifer.

Hydrology and simulation of ground-water flow in Juab Valley, Juab County, Utah.

USGS Publications Warehouse

Thiros, Susan A.; Stolp, Bernard J.; Hadley, Heidi K.; Steiger, Judy I.

1996-01-01

Plans to import water to Juab Valley, Utah, primarily for irrigation, are part of the Central Utah Project. A better understanding of the hydrology of the valley is needed to help manage the water resources and to develop conjunctive-use plans.The saturated unconsolidated basin-fill deposits form the ground-water system in Juab Valley. Recharge is by seepage from streams, unconsumed irrigation water, and distribution systems; infiltration of precipitation; and subsurface inflow from consolidated rocks that surround the valley. Discharge is by wells, springs, seeps, evapotranspiration, and subsurface outflow to consolidated rocks. Ground-water pumpage is used to supplement surface water for irrigation in most of the valley and has altered the direction of groundwater flow from that of pre-ground-water development time in areas near and in Nephi and Levan.Greater-than-average precipitation during 1980-87 corresponds with a rise in water levels measured in most wells in the valley and the highest water level measured in some wells. Less-than average precipitation during 1988-91 corresponds with a decline in water levels measured during 1988-93 in most wells. Geochemical analyses indicate that the sources of dissolved ions in water sampled from the southern part of the valley are the Arapien Shale, evaporite deposits that occur in the unconsolidated basin-fill deposits, and possibly residual sea water that has undergone evaporation in unconsolidated basin-fill deposits in selected areas. Water discharging from a spring at Burriston Ponds is a mixture of about 70 percent ground water from a hypothesized flow path that extends downgradient from where Salt Creek enters Juab Valley and 30 percent from a hypothesized flow path from the base of the southern Wasatch Range.The ground-water system of Juab Valley was simulated by using the U.S. Geological Survey modular, three-dimensional, finite-difference, ground-water flow model. The numerical model was calibrated to simulate the steady-state conditions of 1949, multi-year transient-state conditions during 1949-92, and seasonal transient-state conditions during 1992-94. Calibration parameters were adjusted until model-computed water levels reasonably matched measured water levels. Parameters important to the calibration process include horizontal hydraulic conductivity, transmissivity, and the spatial distribution and amount of recharge from subsurface inflow and seepage from ephemeral streams to the east side of Juab Valley.

Denitrification in a sand and gravel aquifer

USGS Publications Warehouse

Smith, R.L.; Duff, J.H.

1988-01-01

Denitrification was assayed by the acetylene blockage technique in slurried core material obtained from a freshwater sand and gravel aquifer. The aquifer, which has been contaminated with treated sewage for more than 50 years, had a contaminant plume greater than 3.5-km long. Near the contaminant source, groundwater nitrate concentrations were greater than 1 mM, whereas 0.25 km downgradient the central portion of the contaminant plume was anoxic and contained no detectable nitrate. Samples were obtained along the longitudinal axis of the plume (0 to 0.25 km) at several depths from four sites. Denitrification was evident at in situ nitrate concentrations at all sites tested; rates ranged from 2.3 to 260 pmol of N20 produced (g of wet sediment)-' h-'. Rates were highest nearest the contaminant source and decreased with increasing distance downgradient. Denitrification was the predominant nitrate-reducing activity; no evidence was found for nitrate reduction to ammonium at any site. Denitrifying activity was carbon limited and not nitrate limited, except when the ambient nitrate level was less than the detection limit, in which case, even when amended with high concentrations of glucose and nitrate, the capacity to denitrify on a short-term basis was lacking. These results demonstrate that denitrification can occur in groundwater systems and, thereby, serve as a mechanism for nitrate remoyal from groundwater.

Contamination of shallow ground water in the area of building 95, Picatinny Arsenal, New Jersey, 1985-90

USGS Publications Warehouse

Sargent, B.P.; Storck, D.A.

1994-01-01

A zone of contaminated ground water at Picatinny Arsenal has resulted from the operation of a metal- plating facility in building 95 during 1960-81, and the wastewater-treatment system that is in and adjacent to the building. Thirty-two monitoring wells were installed in 1989 to supplement 12 previously installed wells. All wells were sampled in 1989 and 1990 for analysis of ground water for inorganic constituents, trace elements, volatile organic compounds, and nutrients. Four wells also were sampled for analysis for base/neutral- and acid-extractable compounds and pesticides, and soil gas from the unsaturated zone at eight sites was analyzed for volatile organic compounds. Concentrations of dissolved solids and sulfate in the study area were consistently above the U.S. Environmental Protection Agency's secondary drinking-water regulations. The areal distribution of sulfate differed from that of the volatile organic compounds. Concentrations of trace elements were not elevated downgradient from the source. The estimated average velocity of contaminant movement is 0.1 to 1.1 feet per day. The major organic contaminants identified in the study area are trichloroethylene, tetrachloroethylene, and 1,1,1-trichloroethane. Trichloroethylene was detected in wells upgradient from the wastewater- treatment site. Tetrachloroethylene and 1,1,1-trichloroethane might originate at tanks in the basement of building 95 rather than at the adjacent wastewater-treatment system. The pre- dominant gas-phase contaminant, 1,1,1- trichloroethane, was detected at a maximum con- centration of 15.7 micrograms per liter. Both trichoroethylene and tetrachloroethylene were detected in concentrations greater than 0.10 micrograms per liter in five of the eight soil- gas samples, indicating that volatilization and diffusion through the unsaturated zone could be a significant mechanism of contaminant loss from the aquifer.

Using analytic element models to delineate drinking water source protection areas.

PubMed

Raymond, Heather A; Bondoc, Michael; McGinnis, John; Metropulos, Kathy; Heider, Pat; Reed, Allison; Saines, Steve

2006-01-01

Since 1999, Ohio EPA hydrogeologists have used two analytic element models (AEMs), the proprietary software GFLOW and U.S. EPA's WhAEM, to delineate protection areas for 535 public water systems. Both models now use the GFLOW2001 solution engine, integrate well with Geographic Information System (GIS) technology, have a user-friendly graphical interface, are capable of simulating a variety of complex hydrogeologic settings, and do not rely upon a model grid. These features simplify the modeling process and enable AEMs to bridge the gap between existing simplistic delineation methods and more complex numerical models. Ohio EPA hydrogeologists demonstrated that WhAEM2000 and GFLOW2000 were capable of producing capture zones similar to more widely accepted models by applying the AEMs to eight sites that had been previously delineated using other methods. After the Ohio EPA delineated protection areas using AEMs, more simplistic delineation methods used by other states (volumetric equation and arbitrary fixed radii) were applied to the same water systems to compare the differences between various methods. GIS software and two-tailed paired t-tests were used to quantify the differences in protection areas and analyze the data. The results of this analysis demonstrate that AEMs typically produce significantly different protection areas than the most simplistic delineation methods, in terms of total area and shape. If the volumetric equation had been used instead of AEMs, Ohio would not have protected 265 km2 of critical upgradient area and would have overprotected 269 km2 of primarily downgradient land. Since an increasing number of land-use restrictions are being tied to drinking water protection areas, this analysis has broad policy implications.

Aquifer test at well SMW-1 near Moenkopi, Arizona

USGS Publications Warehouse

Carruth, Rob; Bills, Donald J.

2012-01-01

The Hopi villages of Lower Moencopi and Upper Moenkopi are on the Hopi Indian Reservation south of Tuba City in northern Arizona. These adjacent Hopi villages, located west and north of the confluence of Pasture Canyon Wash and Moenkopi Wash, are dependent on groundwater withdrawals from three wells that penetrate the N aquifer and from two springs that discharge from the N aquifer. The N aquifer is the principal aquifer in this region of northern Arizona and is composed of thick beds of sandstone between less permeable layers of siltstone and mudstone. The fine-grained character of the N aquifer inhibits rapid movement of water and large yields to wells; however, the aquifer is moderately productive at yields generally less than 25 gallons per minute in the study area. In recent years, the water level has declined in the three public-supply wells and the flow from the springs has decreased, causing concern that the current water supply will not be able to accommodate peak demand and allow for residential and economic growth. In addition to the challenge imposed by declining groundwater levels, the water-supply wells and springs are located about 2 miles downgradient from the Tuba City Landfill site where studies are ongoing to determine if uranium and other metals in groundwater beneath the landfill are higher than regional concentrations in the N aquifer. In August 2008, the U.S. Geological Survey, in cooperation with the Hopi Tribe, conducted an aquifer test on well SMW-1, designed to help the Hopi Tribe determine the potential yield and water quality of the N aquifer south of Moenkopi Wash as a possible source of additional water supply. Well SMW-1 was drilled south of Moenkopi Wash to a depth of 760 feet below land surface before being backfilled and cased to about 300 feet. The well penetrates, in descending order, the Navajo Sandstone and the Kayenta Formation, both units of the N aquifer. The pre-test water level in the well was 99.15 feet below land surface. A 9.25-hour step-drawdown test and a 72-hour constant-rate test followed by recovery tests were used to investigate the performance of the test well and to estimate the transmissivity and potential yield of the N aquifer south of Moenkopi Wash. The test data were analyzed using the Cooper-Jacob method adjusted for confined conditions, the Papadopulos-Cooper method that accounts for wellbore storage, and the Theis method on the recovery data. Results of the tests indicate that in the vicinity of the well, the N aquifer has a transmissivity of about 50 feet squared per day. The test well, as completed, should yield about 15 gallons per minute with about 75 feet of drawdown (less than half of the available saturated thickness of the aquifer at the well).

Water, Energy and Carbon Balance Research: Recovery Trajectories For Oil Sands Reclamation and Disturbed Watersheds in the Western Boreal Forest

NASA Astrophysics Data System (ADS)

Petrone, R. M.; Carey, S. K.

2014-12-01

The Oil Sand Region (OSR) of North-Central Alberta exists within the sub-humid Boreal Plains (BP) ecozone, with a slight long-term moisture deficit regime. Despite this deficit, the BP is comprised of productive wetland and mixed wood (aspen and conifer dominated) forests. Reclamation activities are now underway at a large number of surface mining operations in the OSR, where target ecosystems are identified, soil prescriptions placed and commercial forest species planted. Some watersheds have been created that now contain wetlands. However, recent work in the BP suggests that over time wetlands supply moisture for the productivity of upland forests. Thus, water use of reclaimed forests is going to be critical in determining the sustainability of these systems and adjacent wetlands, and whether in time, either will achieve some form of equivalent capability that will allow for certification by regulators. A critical component in the success of any reclamation is that sufficient water is available to support target ecosystems through the course of natural climate cycles in the region. Water Use Efficiency (WUE), which links photosynthesis (GEP) with water use (Evapotranspiration (ET)), provides a useful metric to compare ecosystems and evaluate their utilization of resources. In this study, 41 site years of total growing season water and carbon flux data over 8 sites (4 reclamation, 4 regeneration) were evaluated using eddy covariance micrometeorological towers. WUE shows clear discrimination among ecosystem types as aspen stands assimilate more carbon per unit weight of water than conifers. WUEs also change with time as ecosystems become more effective at transpiring water through plant pathways compared with bare-soil evaporation, which allows an assessment of ability to limit water loss without carbon uptake. In addition, clonal rooting systems allow aspen forests to recover quicker after disturbance than reclamation sites in terms of their WUE. For reclamation sites, there is considerable variability in GEP and ET associated with vegetation establishment, with enhanced ET losses over-riding any significant changes in C uptake, suggesting that long-term mine water management must consider ecosystem pathways if down-gradient wetlands and end-pit lakes are to be sustained.

Questa baseline and pre-mining ground-water quality investigation. 5. Well installation, water-level data, and surface- and ground-water geochemistry in the Straight Creek drainage basin, Red River Valley, New Mexico, 2001-03

USGS Publications Warehouse

Naus, Cheryl A.; McCleskey, R. Blaine; Nordstrom, D. Kirk; Donohoe, Lisa C.; Hunt, Andrew G.; Paillet, Frederick L.; Morin, Roger H.; Verplanck, Philip L.

2005-01-01

The U.S. Geological Survey, in cooperation with the New Mexico Environment Department, is investigating the pre-mining ground-water chemistry at the Molycorp molybdenum mine in the Red River Valley, northern New Mexico. The primary approach is to determine the processes controlling ground-water chemistry at an unmined, off-site, proximal analog. The Straight Creek drainage basin, chosen for this purpose, consists of the same quartz-sericite-pyrite altered andesitic and rhyolitic volcanic rock of Tertiary age as the mine site. The weathered and rugged volcanic bedrock surface is overlain by heterogeneous debris-flow deposits that interfinger with alluvial deposits near the confluence of Straight Creek and the Red River. Pyritized rock in the upper part of the drainage basin is the source of acid rock drainage (pH 2.8-3.3) that infiltrates debris-flow deposits containing acidic ground water (pH 3.0-4.0) and bedrock containing water of circumneutral pH values (5.6-7.7). Eleven observation wells were installed in the Straight Creek drainage basin. The wells were completed in debris-flow deposits, bedrock, and interfingering debris-flow and Red River alluvial deposits. Chemical analyses of ground water from these wells, combined with chemical analyses of surface water, water-level data, and lithologic and geophysical logs, provided information used to develop an understanding of the processes contributing to the chemistry of ground water in the Straight Creek drainage basin. Surface- and ground-water samples were routinely collected for determination of total major cations and selected trace metals; dissolved major cations, selected trace metals, and rare-earth elements; anions and alkalinity; and dissolved-iron species. Rare-earth elements were determined on selected samples only. Samples were collected for determination of dissolved organic carbon, mercury, sulfur isotopic composition (34S and 18O of sulfate), and water isotopic composition (2H and 18O) during selected samplings. One set of ground-water samples was collected for helium-3/tritium and chlorofluorocarbon (CFC) age dating. Several lines of evidence indicate that surface water is the primary input to the Straight Creek ground-water system. Straight Creek streamflow and water levels in wells closest to the apex of the Straight Creek debris fan and closest to Straight Creek itself appear to respond to the same seasonal inputs. Oxygen and hydrogen isotopic compositions in Straight Creek surface water and ground water are similar, and concentrations of most dissolved constituents in most Straight Creek surface-water and shallow (debris-flow and alluvial) aquifer ground-water samples correlate strongly with sulfate (concentrations decrease linearly with sulfate in a downgradient direction). After infiltration of surface water, dilution along the flow path is the dominant mechanism controlling ground-water chemistry. However, concentrations of some constituents can be higher in ground water than can be accounted for by concentrations in Straight Creek surface water, and additional sources of these constituents must therefore be inferred. Constituents for which concentrations in ground water can be high relative to surface water include calcium, magnesium, strontium, silica, sodium, and potassium in ground water from debris-flow and alluvial aquifers and manganese, calcium, magnesium, strontium, sodium, and potassium in ground water from the bedrock aquifer. All ground water is a calcium sulfate type, often at or near gypsum saturation because of abundant gypsum in the aquifer material developed from co-existing calcite and pyrite mineralization. Calcite dissolution, the major buffering mechanism for bedrock aquifer ground water, also contributes to relatively higher calcium concentrations in some ground water. The main source of the second most abundant cation, magnesium, is probably dissolution of magnesium-rich carbonates or silicates. Strontium may also be

Identification of alkylphenols and other estrogenic compounds in wastewater, septage, and groundwater on Cape Cod, Massachusetts

USGS Publications Warehouse

Rudel, Ruthann A.; Melly, Steven J.; Geno, Paul W.; Sun, Gang; Brody , Julia G.

1998-01-01

As part of a larger effort to characterize the impacts to Cape Cod drinking water supplies from on-site wastewater disposal, we developed two analytical methods using HPLC and GC/MS for a range of compounds identified as endocrine-disrupting chemicals (EDCs), including the nonionic surfactants alkylphenol polyethoxylates (APEOs) and their degradation products. We analyzed samples for nonylphenol, octylphenol, and their ethoxylates up to the hexaethoxylate using an HPLC method, with detection limits ranging from 2 to 6 μg/L. A set of phenolic compounds including bisphenol A and nonylphenol were derivatized and analyzed by GC/MS with detection limits from 0.001 to 0.02 μg/L. Total APEOs in untreated wastewater and septage samples ranged from 1350 to 11 000 μg/L by the HPLC method. Nonylphenol was detected in all septage samples at concentrations above 1000 μg/L. Phenylphenol and bisphenol A were detected in septage and wastewater at about 1 μg/L. In groundwater downgradient of an infiltration bed for secondary treated effluent, nonyl/octylphenol and ethoxylates were present at about 30 μg/L. Bisphenol A, nonylphenol monoethoxycarboxylate, and nonyl/octylphenol tetraethoxylate were detected in some drinking water wells at concentrations ranging from below the quantitation limit to 32.9 μg/L. Results suggest that septic systems may be a significant source of APEOs to groundwater.

Leachate migration from an in-situ oil-shale retort near Rock Springs, Wyoming

USGS Publications Warehouse

Glover, Kent C.

1988-01-01

Hydrogeologic factors influencing leachate movement from an in-situ oil-shale retort near Rock Springs, Wyoming, were investigated through models of ground-water flow and solute transport. Leachate, indicated by the conservative ion thiocyanate, has been observed ? mile downgradient from the retort. The contaminated aquifer is part of the Green River Formation and consists of thin, permeable layers of tuff and sandstone interbedded with oil shale. Most solute migration has occurred in an 8-foot sandstone at the top of the aquifer. Ground-water flow in the study area is complexly three dimensional and is characterized by large vertical variations in hydraulic head. The solute-transport model was used to predict the concentration of thiocyanate at a point where ground water discharges to the land surface. Leachate with peak concentrations of thiocyanate--45 milligrams per liter or approximately one-half the initial concentration of retort water--was estimated to reach the discharge area during January 1985. This report describes many of th3 advantages, as well as the problems, of site-specific studies. Data such as the distribution of thin, permeable beds or fractures might introduce an unmanageable degree of complexity to basin-wide studies but can be incorporated readily into site-specific models. Solute migration in the study area occurs primarily in thin, permeable beds rather than in oil-shale strata. Because of this behavior, leachate traveled far greater distances than might otherwise have been expected. The detail possible in site-specific models permits more accurate prediction of solute transport than is possible with basin-wide models. A major problem in site-specific studies is identifying model boundaries that permit the accurate estimation of aquifer properties. If the quantity of water flowing through a study area cannot be determined prior to modeling, the hydraulic conductivity and ground-water velocity will be poorly estimated.

A study of the characteristics of karst groundwater circulation based on multi-isotope approach in the Liulin spring area, North China.

PubMed

Zang, Hongfei; Zheng, Xiuqing; Qin, Zuodong; Jia, Zhenxing

2015-01-01

Due to the significance of karst groundwater for water supply in arid and semi-arid regions, the characteristics of the karst groundwater flow system in the Liulin spring area, North China, are analysed through isotopic tracing (δ(2)H, δ(18)O, δ(13)C and (3)H) and dating approaches ((14)C). The results show that the primary recharge source of karst groundwater is precipitation. Evaporation during dropping and infiltration of rainfall results in a certain offset in the values of δ(2)H and δ(18)O in groundwater samples from the global meteoric water line (GMWL) and the local meteoric water line (LMWL). The altitudes of the recharge region calculated by δ(18)O range from 1280 to 2020 m above sea level, which is consistent with the altitudes of the recharge area. The Liulin spring groups could be regarded as the mixing of groundwater with long and short flow paths at a ratio of 4:1. In the upgradient of the Liulin spring, the groundwater represents modern groundwater features and its [Formula: see text] is mainly derived from dissolution of soil CO(2), while in the downgradient of the Liulin spring, the (14)C age of dissolved inorganic carbon (DIC) in groundwater shows an apparent increase and [Formula: see text] is mainly derived from the dissolution of carbonate rocks. The mean flow rate calculated by (14)C ages of DIC between IS10 and IS12 is 1.23 m/year.

Distribution of microbial physiologic types in an aquifer contaminated by crude oil

USGS Publications Warehouse

Bekins, B.A.; Godsy, E.M.; Warren, E.

1999-01-01

We conducted a plume-scale study of the microbial ecology in the anaerobic portion of an aquifer contaminated by crude-oil compounds. The data provide insight into the patterns of ecological succession, microbial nutrient demands, and the relative importance of free-living versus attached microbial populations. The most probable number (MPN) method was used to characterize the spatial distribution of six physiologic types: aerobes, denitrifiers, iron-reducers, heterotrophic fermenters, sulfate-reducers, and methanogens. Both free-living and attached numbers were determined over a broad cross-section of the aquifer extending horizontally from the source of the plume at a nonaqueous oil body to 66 m downgradient, and vertically from above the water table to the base of the plume below the water table. Point samples from widely spaced locations were combined with three closely spaced vertical profiles to create a map of physiologic zones for a cross-section of the plume. Although some estimates suggest that less than 1% of the subsurface microbial population can be grown in laboratory cultures, the MPN results presented here provide a comprehensive qualitative picture of the microbial ecology at the plume scale. Areas in the plume that are evolving from iron-reducing to methanogenic conditions are clearly delineated and generally occupy 25-50% of the plume thickness. Lower microbial numbers below the water table compared to the unsaturated zone suggest that nutrient limitations may be important in limiting growth in the saturated zone. Finally, the data indicate that an average of 15% of the total population is suspended.

Parameter-Adaptive Model-Following for In-Flight Simulation.

DTIC Science & Technology

1987-12-01

simulation architechture through the use of "smart" simulation cockpits for increased simulation capability and fidelity. Most recently, he has been...OF REPORT Approved for public release; U Lribution2b. DECLASSIFICATiON/DOWNGRADiNG SCHEDULE unlimited. 4. PERFORMING ORGANIZATION REPORT NUMBER(S) 5...MONiTOR!NG ORGANIZATICN REPORT NUMBER(S, AFIT/GE/ENG/87D-74 6a. NAME OF PERFORMING ORGANIZATION 6b. OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION

Chromium isotope variation along a contaminated groundwater plume: a coupled Cr(VI)- reduction, advective mixing perspective

NASA Astrophysics Data System (ADS)

Bullen, T.; Izbicki, J.

2007-12-01

Chromium (Cr) is a common contaminant in groundwater, used in electroplating, leather tanning, wood preservation, and as an anti-corrosion agent. Cr occurs in two oxidation states in groundwater: Cr(VI) is highly soluble and mobile, and is a carcinogen; Cr(III) is generally insoluble, immobile and less toxic than Cr(VI). Reduction of Cr(VI) to Cr(III) is thus a central issue in approaches to Cr(VI) contaminant remediation in aquifers. Aqueous Cr(VI) occurs mainly as the chromate (CrO22-) and bichromate (HCrO2-) oxyanions, while Cr(III) is mainly "hexaquo" Cr(H2O)63+. Cr has four naturally-occurring stable isotopes: 50Cr, 52Cr, 53Cr and 54Cr. When Cr(VI) is reduced to Cr(III), the strong Cr-O bond must be broken, resulting in isotopic selection. Ellis et al. (2002) demonstrated that for reduction of Cr(VI) on magnetite and in natural sediment slurries, the change of isotopic composition of the remnant Cr(VI) pool was described by a Rayleigh fractionation model having fractionation factor ɛCr(VI)-Cr(III) = 3.4‰. We attempted to use Cr isotopes as a monitor of Cr(VI) reduction at a field site in Hinkley, California (USA) where groundwater contaminated with Cr(VI) has been under assessment for remediation. Groundwater containing up to 5 ppm Cr(VI) has migrated down-gradient from the contamination source through the fluvial to alluvial sediments to form a well-defined plume. Uncontaminated groundwater in the aquifer immediately adjacent to the plume has naturally-occurring Cr(VI) of 4 ppb or less (CH2M-Hill). In early 2006, colleagues from CH2M-Hill collected 17 samples of groundwater from within and adjacent to the plume. On a plot of δ53Cr vs. log Cr(VI), the data array is strikingly linear and differs markedly from the trend predicted for reduction of Cr(VI) in the contaminated water. There appear to be two groups of data: four samples with δ53Cr >+2‰ and Cr(VI) <4 ppb, and 13 samples with δ53Cr <+2‰ and Cr(VI) >15 ppb. Simple mixing lines between the groundwater samples having <4 ppb Cr(VI), taken to be representative of regional groundwater, and the contaminated water do not pass through the remainder of the data, discounting a simple advective mixing scenario. We hypothesize a more likely scenario that involves both Cr(VI) reduction and advective mixing. As the plume initially expands downgradient, Cr(VI) in water at the leading edge encounters reductant in the aquifer resulting in limited Cr(VI) reduction. As a result of reduction, δ53Cr of Cr(VI) remaining in solution at the leading edge increases along the "reduction" trend from 0 to ~+2‰. Inevitable mixing of this water at the leading edge with regional groundwater results in a suitable mixing end-member to combine with Cr(VI) within the plume in order to explain the bulk of the remaining data. Neither Cr(VI) reduction nor advective mixing of plume and regional groundwaters can explain the data on their own, implying an interplay of at least these two processes during plume evolution. Ellis, A.S., Johnson, T.M. and Bullen, T.D. 2002, Science, 295, 2060-2062.

Submarine ground-water discharge: nutrient loading and nitrogen transformations

USGS Publications Warehouse

Kroeger, Kevin D.; Swarzenski, Peter W.; Crusius, John; Bratton, John F.; Charette, Matthew A.

2006-01-01

Eutrophication of coastal waters due to nonpoint source land-derived nitrogen (N) loads is a worldwide phenomenon and perhaps the greatest agent of change altering coastal ecology (National Research Council, 2000; Howarth and others, 2000). Within the United States, a majority of estuaries have been determined to be moderately to severely impaired by eutrophication associated with increasing nutrient loads (Bricker and others, 1999).In coastal watersheds with soils of high hydraulic conductivity and permeable coastal sediments, ground water is a major route of transport of freshwater and its solutes from land to sea. Freshwater flowing downgradient from aquifers may either discharge from a seepage face near the intertidal zone, or flow directly into the sea as submarine ground-water discharge (SGD) (fig. 1). In the coastal aquifer, entrainment of saline pore water occurs prior to discharge, producing a gradient in ground-water salinity from land to sea, referred to as a subterranean estuary (Moore, 1999). In addition, processes including density-driven flow and tidal pumping create brackish and saline ground-water circulation. Hence, submarine ground-water discharge often consists of a substantial amount of recirculating seawater. Mixing of fresh and saline ground waters in the context of coastal sediments may alter the chemical composition of the discharging fluid. Depending on the biogeochemical setting, removal of fixed N due to processes leading to N2 (dinitrogen gas) production in the nearshore aquifer and subterranean estuary may significantly attenuate land-derived N loads; or, processes such as ion exchange and tidal pumping in the subterranean estuary may substantially accelerate the transport of both land-derived and sediment re-mineralized N to estuarine water columns.As emphasized by Burnett and others (2001, 2002), a fundamental problem in evaluating the importance of ground-water discharge in marine geochemical budgets is the difficulty of collecting samples across the salinity gradients of coastal aquifers. In addition, locating and quantifying rates of submarine ground-water discharge remains a challenge due to the diffuse and spatially and temporally heterogeneous nature of discharge. As a result, with regard to the study of biogeochemical cycles and chemical loads to coastal waters, the seepage face and subterranean estuary are relatively new and under-studied zones in the aquatic cascade from watershed to sea. Processes occurring in those zones must be understood and considered for proper modeling and management of coastal water resources.

Long-term groundwater contamination after source removal—The role of sorbed carbon and nitrogen on the rate of reoxygenation of a treated-wastewater plume on Cape Cod, MA, USA

USGS Publications Warehouse

Smith, Richard L.; Repert, Deborah A.; Barber, Larry B.; LeBlanc, Denis R.

2013-01-01

The consequences of groundwater contamination can remain long after a contaminant source has been removed. Documentation of natural aquifer recoveries and empirical tools to predict recovery time frames and associated geochemical changes are generally lacking. This study characterized the long-term natural attenuation of a groundwater contaminant plume in a sand and gravel aquifer on Cape Cod, Massachusetts, after the removal of the treated-wastewater source. Although concentrations of dissolved organic carbon (DOC) and other soluble constituents have decreased substantially in the 15 years since the source was removed, the core of the plume remains anoxic and has sharp redox gradients and elevated concentrations of nitrate and ammonium. Aquifer sediment was collected from near the former disposal site at several points in time and space along a 0.5-km-long transect extending downgradient from the disposal site and analyses of the sediment was correlated with changes in plume composition. Total sediment carbon content was generally low (< 8 to 55.8 μmol (g dry wt)− 1) but was positively correlated with oxygen consumption rates in laboratory incubations, which ranged from 11.6 to 44.7 nmol (g dry wt)− 1 day− 1. Total water extractable organic carbon was < 10–50% of the total carbon content but was the most biodegradable portion of the carbon pool. Carbon/nitrogen (C/N) ratios in the extracts increased more than 10-fold with time, suggesting that organic carbon degradation and oxygen consumption could become N-limited as the sorbed C and dissolved inorganic nitrogen (DIN) pools produced by the degradation separate with time by differential transport. A 1-D model using total degradable organic carbon values was constructed to simulate oxygen consumption and transport and calibrated by using observed temporal changes in oxygen concentrations at selected wells. The simulated travel velocity of the oxygen gradient was 5–13% of the groundwater velocity. This suggests that the total sorbed carbon pool is large relative to the rate of oxygen entrainment and will be impacting groundwater geochemistry for many decades. This has implications for long-term oxidation of reduced constituents, such as ammonium, that are being transported downgradient away from the infiltration beds toward surface and coastal discharge zones.

Digital modeling of radioactive and chemical waste transport in the aquifer underlying the Snake River Plain at the National Reactor Testing Station, Idaho

USGS Publications Warehouse

Robertson, J.B.

1974-01-01

Industrial and low-level radioactive liquid wastes at the National Reactor Testing Station (NRTS) in Idaho have been disposed to the Snake River Plain aquifer since 1952. Monitoring studies have indicated that tritium and chloride have dispersed over a 15-square mile (39-square kilometer) area of the aquifer in low but detectable concentrations and have only migrated as far as 5 miles (8 kilometers) downgradient from discharge points. The movement of cationic waste solutes, particularly 90Sr and 137Cs, has been significantly retarded due to sorption phenomena, principally ion exchange. 137Cs has shown no detectable migration in the aquifer and 90Sr has migrated only about 1.5 miles (2 kilometers) from the Idaho Chemical Processing Plant (ICPP) discharge well, and is detectable over an area of only 1.5 square miles ( 4 square kilometers) of the aquifer. Digital modeling techniques have been applied successfully to the analysis of the complex waste-transport system by utilizing numerical solution of the coupled equations of groundwater motion and mass transport. The model includes the effects of convective transport, flow divergence, two-dimensional hydraulic dispersion, radioactive decay, and reversible linear sorption. The hydraulic phase of the model uses the iterative, alternating direction, implicit finite-difference scheme to solve the groundwater flow equations, while the waste-transport phase uses a modified method of characteristics to solve the solute transport equations simulated by the model. The modeling results indicate that hydraulic dispersion (especially transverse) is a much more significant influence than previously suggested by earlier studies. The model has been used to estimate future waste migration patterns for varied assumed hydrological and waste conditions up through the year 2000. The hydraulic effects of recharge from the Big Lost River have an important (but not predominant) influence on the simulated future migration patterns. For the assumed conditions, the model indicates that detectable concentrations of waste chloride and tritium could move as much as 15 miles (24 kilometers) downgradient from the original discharge points by the year 2000. However, the model shows 90Sr moving only 2 to 3 miles (3 to 5 kilometers) downgradient in the same time. The model may also be used to estimate the effects of the various future waste disposal practices and hydrologic conditions on subsequent migration of waste products.

Hydrogeologic Setting and Ground-Water Flow in the Leetown Area, West Virginia

USGS Publications Warehouse

Kozar, Mark D.; Weary, David J.; Paybins, Katherine S.; Pierce, Herbert A.

2007-01-01

The Leetown Science Center is a research facility operated by the U.S. Geological Survey that occupies approximately 455-acres near Kearneysville, Jefferson County, West Virginia. Aquatic and fish research conducted at the Center requires adequate supplies of high-quality, cold ground water. Three large springs and three production wells currently (in 2006) supply water to the Center. The recent construction of a second research facility (National Center for Cool and Cold Water Aquaculture) operated by the U.S. Department of Agriculture and co-located on Center property has placed additional demands on available water resources in the area. A three-dimensional steady-state finite-difference ground-water flow model was developed to simulate ground-water flow in the Leetown area and was used to assess the availability of ground water to sustain current and anticipated future demands. The model also was developed to test a conceptual model of ground-water flow in the complex karst aquifer system in the Leetown area. Due to the complexity of the karst aquifer system, a multidisciplinary research study was required to define the hydrogeologic setting. Geologic mapping, surface- and borehole-geophysical surveys, stream base-flow surveys, and aquifer tests were conducted to provide the hydrogeologic data necessary to develop and calibrate the model. It would not have been possible to develop a numerical model of the study area without the intensive data collection and methods developments components of the larger, more comprehensive hydrogeologic investigation. Results of geologic mapping and surface-geophysical surveys verified the presence of several prominent thrust faults and identified additional faults and other complex geologic structures (including overturned anticlines and synclines) in the area. These geologic structures are known to control ground-water flow in the region. Results of this study indicate that cross-strike faults and fracture zones are major avenues of ground-water flow. Prior to this investigation, the conceptual model of ground-water flow for the region focused primarily on bedding planes and strike-parallel faults and joints as controls on ground-water flow but did not recognize the importance of cross-strike faults and fracture zones that allow ground water to flow downgradient across or through less permeable geologic formations. Results of the ground-water flow simulation indicate that current operations at the Center do not substantially affect either streamflow (less than a 5-percent reduction in annual streamflow) or ground-water levels in the Leetown area under normal climatic conditions but potentially could have greater effects on streamflow during long-term drought (reduction in streamflow of approximately 14 percent). On the basis of simulation results, ground-water withdrawals based on the anticipated need for an additional 150 to 200 gal/min (gallons per minute) of water at the Center also would not seriously affect streamflow (less than 8 to 9 percent reduction in streamflow) or ground-water levels in the area during normal climatic conditions. During drought conditions, however, the effects of current ground-water withdrawals and anticipated additional withdrawals of 150 to 200 gal/min to augment existing supplies result in moderate to substantial declines in water levels of 0.5-1.2 feet (ft) in the vicinity of the Center's springs and production wells. Streamflow was predicted to be reduced locally by approximately 21 percent. Such withdrawals during a drought or prolonged period of below normal ground-water levels would result in substantial declines in the flow of the Center's springs and likely would not be sustainable for more than a few months. The drought simulated in this model was roughly equivalent to the more than 1-year drought that affected the region from November 1998 through February 2000. The potential reduction in streamflow is a result of capture of ground water tha

Geophysical logs and water-quality data collected for boreholes Kimama-1A and -1B, and a Kimama water supply well near Kimama, southern Idaho

USGS Publications Warehouse

Twining, Brian V.; Bartholomay, Roy C.

2011-01-01

In September 2010, a research consortium led by scientists from Utah State University began drilling the first of three continuously cored boreholes on the Snake River Plain in southern Idaho. The goals of this effort, the Snake River Scientific Drilling Project, are to study the interaction between the Earth's crust and mantle, to identify potential geothermal energy sources, and to track the evolution of the Yellowstone hotspot on the Snake River Plain. The first borehole, located near Kimama, Idaho, is about 50 miles southwest of the U.S. Department of Energy's Idaho National Laboratory. Because geohydrologic data are scarce for that area of the central Snake River Plain, the Kimama borehole, completed in January 2011, provided a unique opportunity to collect geophysical and water-chemistry data from the eastern Snake River Plain aquifer system, downgradient of the laboratory. Therefore, in conjunction with the Snake River Scientific Drilling Project, scientists from the U.S. Geological Survey's Idaho National Laboratory Project Office conducted geophysical logging and collected water samples at the Kimama site. Wireline geophysical logs were collected for the diverging borehole, Kimama-1A and -1B, from land surface to 976 and 2,498 feet below land surface (BLS), respectively. Water samples were collected from Kimama-1A at depths near 460 and 830 feet BLS, and from the Kimama Water Supply (KWS) well located about 75 feet away. Geophysical log data included a composite of natural gamma, neutron, gamma-gamma dual density, and gyroscopic analysis for boreholes Kimama-1A and -1B. Geophysical logs depicted eight sediment layers (excluding surficial sediment) ranging from 4 to 60 feet in thickness. About 155 individual basalt flows were identified, ranging from less than 3 feet to more than 175 feet in thickness (averaging 15 feet) for borehole Kimama-1B (0 to 2,498 feet BLS). Sediment and basalt contacts were selected based on geophysical traces and were confirmed with visual inspection of core photographs. Temperature logs from the water table surface (about 260 feet BLS) to the bottom of borehole Kimama-1B (2,498 feet BLS) were nearly isothermal, ranging from about 62 to 64 degrees Fahrenheit. Gyroscopic data revealed that borehole Kimama-1B begins to separate from borehole Kimama-1A near a depth of 676 feet BLS. Drillhole azimuth and horizontal deviation at total logged depth for boreholes Kimama-1A and -1B were 172.6 and 188.3 degrees and 25.9 and 82.0 feet, respectively. Water samples were collected and analyzed for common ions; selected trace elements; nutrients; isotopes of hydrogen, oxygen, and carbon; and selected radionuclides. One set of water samples was collected from the KWS well and the two other sample sets were collected from borehole Kimama-1A near 460 and 830 feet BLS. With one exception, data for all three zones sampled near Kimama generally indicated that the water chemistry was similar. The exception was found in the deepest zone in borehole Kimama-1A (830 feet BLS) where concentrations probably were affected by the drilling mud. A comparison of the inorganic, organic, and stable chemistry data between the KWS well and the 460-foot zone in borehole Kimama-1A indicated similar chemistry of the aquifer water, except for some variability with nitrate plus nitrite, orthophosphate, iron, zinc, and carbon-14. Radionuclide concentrations were either less than reporting levels or at background levels for the eastern Snake River Plain aquifer.

Superfund record of decision (EPA Region 1): Otis Air National Guard (containment of 7 groundwater plumes), Falmouth, MA, September 25, 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1996-03-01

The Massachusetts Military Reservation (MMR) on Cape Cod, Massachusettes lies within the boundaries of Bourne, Mashpee, and Sandwich, and abuts Falmouth. Seven groundwater contaminant plumes have migrated beyond or are approaching the installation boundary. This interim remedial action will intercept the contaminated groundwater plumes to prevent further downgradient movement of the contaminants. Extraction and treatment will continue until the final remedy for the site is chosen.

Fifteen-year assessment of a permeable reactive barrier for treatment of chromate and trichloroethylene in groundwater.

PubMed

Wilkin, Richard T; Acree, Steven D; Ross, Randall R; Puls, Robert W; Lee, Tony R; Woods, Leilani L

2014-01-15

The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminant treatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium source zone, reactive and hydraulic longevity of the PRB has outlived the mobile chromate plume. Chromium concentrations exceeding 3 μg/L have not been detected in regions located hydraulically down-gradient of the PRB. Trichloroethylene treatment has also been effective, although non-constant influent concentrations of trichloroethylene have at times resulted in incomplete dechlorination. Daughter products: cis-1,2-dichloroethylene, vinyl chloride, ethene, and ethane have been observed within and down-gradient of the PRB at levels <10% of the influent trichloroethylene. Analysis of potentiometric surfaces up-gradient and across the PRB suggests that the PRB may currently represent a zone of reduced hydraulic conductivity; however, measurements of the in-situ hydraulic conductivity provide values in excess of 200 m/d in some intervals and indicate no discernible loss of bulk hydraulic conductivity within the PRB. The results presented here are particularly significant because they provide the longest available record of performance of a PRB. The longevity of the Elizabeth City PRB is principally the result of favorable groundwater geochemistry and hydrologic properties of the site. © 2013.

Denitrification in a Sand and Gravel Aquifer

PubMed Central

Smith, Richard L.; Duff, John H.

1988-01-01

Denitrification was assayed by the acetylene blockage technique in slurried core material obtained from a freshwater sand and gravel aquifer. The aquifer, which has been contaminated with treated sewage for more than 50 years, had a contaminant plume greater than 3.5-km long. Near the contaminant source, groundwater nitrate concentrations were greater than 1 mM, whereas 0.25 km downgradient the central portion of the contaminant plume was anoxic and contained no detectable nitrate. Samples were obtained along the longitudinal axis of the plume (0 to 0.25 km) at several depths from four sites. Denitrification was evident at in situ nitrate concentrations at all sites tested; rates ranged from 2.3 to 260 pmol of N2O produced (g of wet sediment)−1 h−1. Rates were highest nearest the contaminant source and decreased with increasing distance downgradient. Denitrification was the predominant nitrate-reducing activity; no evidence was found for nitrate reduction to ammonium at any site. Denitrifying activity was carbon limited and not nitrate limited, except when the ambient nitrate level was less than the detection limit, in which case, even when amended with high concentrations of glucose and nitrate, the capacity to denitrify on a short-term basis was lacking. These results demonstrate that denitrification can occur in groundwater systems and, thereby, serve as a mechanism for nitrate removal from groundwater. PMID:16347621

Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anirban, Basu; Schilling, Kathrin; Brown, Shaun T.

One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradientmore » wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ 82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ 82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation of Se oxyanions at ISR sites.« less

Prevalence of antibiotic resistance genes in bacterial communities associated with Cladophora glomerata mats along the nearshore of Lake Ontario.

PubMed

Ibsen, Michael; Fernando, Dinesh M; Kumar, Ayush; Kirkwood, Andrea E

2017-05-01

The alga Cladophora glomerata can erupt in nuisance blooms throughout the lower Great Lakes. Since bacterial abundance increases with the emergence and decay of Cladophora, we investigated the prevalence of antibiotic resistance (ABR) in Cladophora-associated bacterial communities up-gradient and down-gradient from a large sewage treatment plant (STP) on Lake Ontario. Although STPs are well-known sources of ABR, we also expected detectable ABR from up-gradient wetland communities, since they receive surface run-off from urban and agricultural sources. Statistically significant differences in aquatic bacterial abundance and ABR were found between down-gradient beach samples and up-gradient coastal wetland samples (ANOVA, Holm-Sidak test, p < 0.05). Decaying and free-floating Cladophora sampled near the STP had the highest bacterial densities overall, including on ampicillin- and vancomycin-treated plates. However, quantitative polymerase chain reaction analysis of the ABR genes ampC, tetA, tetB, and vanA from environmental communities showed a different pattern. Some of the highest ABR gene levels occurred at the 2 coastal wetland sites (vanA). Overall, bacterial ABR profiles from environmental samples were distinguishable between living and decaying Cladophora, inferring that Cladophora may control bacterial ABR depending on its life-cycle stage. Our results also show how spatially and temporally dynamic ABR is in nearshore aquatic bacteria, which warrants further research.

Se Isotopes as groundwater redox indicators: Detecting natural attenuation of Se at an in situ recovery U mine

DOE PAGES

Anirban, Basu; Schilling, Kathrin; Brown, Shaun T.; ...

2016-08-22

One of the major ecological concerns associated with the in situ recovery (ISR) of uranium (U) is the environmental release of soluble, toxic selenium (Se) oxyanions generated by mining. Post-mining natural attenuation by the residual reductants in the ore body and reduced down-gradient sediments should mitigate the risk of Se contamination in groundwater. Here in this work, we investigate the Se concentrations and Se isotope systematics of groundwater and of U ore bearing sediments from an ISR site at Rosita, TX, USA. Our results show that selenate (Se(VI)) is the dominant Se species in Rosita groundwater, and while several up-gradientmore » wells have elevated Se(VI), the majority of the ore zone and down-gradient wells have little or no Se oxyanions. In addition, the δ 82SeVI of Rosita groundwater is generally elevated relative to the U ore up to +6.14‰, with the most enriched values observed in the ore-zone wells. Increasing δ 82Se with decreasing Se(VI) conforms to a Rayleigh type distillation model with an ε of $-$2.25‰ ± 0.61‰, suggesting natural Se(VI) reduction occurring along the hydraulic gradient at the Rosita ISR site. Moreover, our results show that Se isotopes are excellent sensors for detecting and monitoring post-mining natural attenuation of Se oxyanions at ISR sites.« less

Ground-water hydrology of the Punjab region of West Pakistan, with emphasis on problems caused by canal irrigation

USGS Publications Warehouse

Greenman, D.W.; Swarzenski, W.V.; Bennett, G.D.

1967-01-01

Rising water tables and the salinization of land as the result of canal irrigation threaten the agricultural economy of the Punjab. Since 1954 the Water and Soils Investigation Division of the West Pakistan Water and Power Development Authority has inventoried the water and soils resources of the Punjab and investigated the relations between irrigation activities, the natural hydrologic factors, and the incidence of waterlogging and subsurface-drainage problems. This report summarizes the findings of the investigation, which was carried out under a cooperative agreement between the Government of Pakistan and the U.S. Agency for International Development, and its predecessor, the U.S. International Cooperation Administration. Leakage from the canal systems, some of which have been in operation for more than 100 years, is the principal cause of rising water levels and constitutes the major component of ground-water recharge in the Punjab. Geologic studies have shown that virtually the entire Punjab is underlain to depths of 1,000 feet or more by unconsolidated alluvium, which is saturated to within a few feet of land surface. The alluvium varies in texture from medium sand to silty clay, but sandy sediments predominate. Large capacity wells, yielding 4 cfs or more, can be developed almost everywhere. Ground water occurring within a depth of 500 feet below the surface averages less than 1,000 ppm of dissolved solids throughout approximately two-thirds of the Punjab. It is estimated that the volume of usable ground water in storage in this part of the alluvial aquifer is on the order of 2 billion acre-feet. In the other one-third of the Punjab, total dissolved solids range from 1,000 to about 20,000 ppm. In about one-half of this area (one-sixth of the area of the Punjab) some ground water can be utilized by diluting with surface water from canals. The ground-water reservoir underlying the Punjab is an unexploited resource of enormous economic value. It is recognized that the scientific management of this ground-water reservoir is the key to permanent irrigation agriculture in the Punjab. The West Pakistan Water .and Power Development Authority has prepared a long-range program for reclaiming the irrigated lands of the Punjab. The essential feature of this program is a proposed network of tubewells (drilled wells) located with an .average density of about one per square mile. Groundwater withdrawals will serve the dual purpose of helping to supply irrigation requirements and of providing subsurface drainage. Despite the feasibility and inherent advantages of tubewell reclamation methods, it is inevitable that just as the superposition of the canal system on the native environment caused undesirable side effects, large-scale ground-water withdrawals again will disturb the hydrologic regimen. The distribtution of withdrawals and maintenance of a favorable salt balance are two distinct, but related aspects of the ground-water budget that present potential hazards that must be considered in the design and management of the tubewell projects. The availability of ground water for irrigation diminishes from northeast to southwest, or downgradient along the doab (an area lying between two rivers) and is negligible in the centers of the lower parts of the doabs, where the ground water is too highly mineralized for use. Ground-water supplies must be developed in areas where they are available and it might become necessary, under a program of maximum exploitation of ground-water resources, to transfer supplies from outside sources to points of use in the lower parts of the doabs. Several factors inherent in the tubewell system will tend to depreciate the quality of ground water with time. Among these are the addition of salts leached from the soils, increased concentration of salts due .to repeated cycles of recirculation, and the possible lateral and upward encroachment of saline water in response to pumping. It is reasonably ce

Behavior of energetic materials in ground water at an anti-tank range.

PubMed

Martel, Richard; Mailloux, Michel; Gabriel, Uta; Lefebvre, René; Thiboutot, Sonia; Ampleman, Guy

2009-01-01

An environmental issue has arisen with M-72 malfunction on anti-tank ranges because many of these rockets break into pieces without exploding on impact, dispersing their energetic materials content on the ground surface and exposing them to transport by infiltration of rainfall and snowmelt. A case study (1998--2005) at Arnhem Anti-Tank Range (Garrison Valcartier, Canada, in operation since the 1970s) revealed octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) contamination and traces of 1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT) in ground water at varying concentrations, with all detected HMX concentrations below the USEPA guideline for drinking water of 400 microg L(-1). An HMX mass balance on a transect perpendicular to ground water flow, about 300 m downgradient of the impact area, indicated an HMX flux of about 3 g d(-1) (0.7-1 kg yr(-1), 2005). The HMX mass in the impact area on the sand terrace was estimated at 7 to 10 kg (in 2005). The annual dissolved HMX flux represents about 10% of the source. The dissolved HMX plume in ground water consisted of a series of slugs, generated at each significant infiltration event. HMX is weakly retarded by sorption and is neither biotransformed nor mineralized under the aerobic conditions of the aquifer. TNT and RDX exceeded the USEPA guideline (2 microg L(-1) RDX and 1 microg L(-1) TNT) in three and two samples, respectively. The TNT plume was discontinuous because this compound was not always present at the ground surface. TNT is biotransformed, weakly sorbed, and not mineralized. In two wells, perchlorate associated with the propellant was found at concentrations above the Health Canada preliminary guideline of 6 microg L(-1) near the firing position.

Hydrogeologic setting and simulation of pesticide fate and transport in the unsaturated zone of a regolith-mantled, carbonate-rock terrain near Newville, Pennsylvania

USGS Publications Warehouse

Hippe, D.J.; Hall, D.W.

1996-01-01

Physical and chemical data were collected from May 1991 through April 1993 at a 4.5 hectare field site in Cumberland County, Pa., about 5 kilometers southeast of Newville. These data were used to define the hydrogeologic setting of a field site representative of the intensively farmed carbonate valleys of southeastern and south-central Pennsylvania. The environmental processing of commonly used pesticides (herbicides, fungicides, and insecticides) in the unsaturated zone was simulated with a process- oriented digital model to evaluate the environmental fate and transport of pesticides to ground water. Site data and modelling results provide a basis for a discussion of water-quality implications of agricultural best-management practices. The carbonate valleys of Pennsylvania comprise regolith-mantled carbonate-rock terrains that consist of broad undulating upland areas dissected by mostly dry valleys and widely spaced spring-fed creeks. The upland areas are farmed and exhibit possess a doline karst topography with many closed depressions, sinkholes, and bedrock outcrops. Unsaturated materials at the field site consist of an almost continuous soil cover composed of fine-grained residuum underlain by an intermediate vadose zone composed of karstified limestone. Soils are absent on scattered bedrock outcrops and are more than 12 meters thick in other areas of the site. The soil profile stores appreciable quantities of water with a volumetric average of about 36 percent water at field capacity. Organic carbon content of soil materials is about 1.7 percent in the Ap-horizon and from 0.1 to 0.3 percent throughout the full thickness of the B- and C-horizons. Atrazine, metolachlor, simazine, and the atrazine soil metabolites deethylatrazine and deisopropylatrazine were detected at concentrations above 0.05 mg/L in just the upper 0.6 meters of soil materials. However, detectable concentrations of atrazine, simazine, and atrazine soil metabolites were measured in water samples from lysimeters installed in soil materials at depths of 1.2, 2.1, and 3.7 meters and from monitor wells completed in the saturated zone to depths of 122 meters. Data collected from the field site were used to configure a pesticide screening model based on the pesticide version of the leaching estimation and chemistry model (LEACHP) developed by Wagenet and Hutson (1987). Model simulations show that most field-applied pesticides volatilize to the atmosphere, accumulate in soils, degrade in the subsurface environment, or leach to ground water. Model results were used to rank the leaching potentials of 66 pesticides. Eighteen of 32 herbicides, 4 of 9 fungicides, and 10 of 25 insecticides have moderate to large potential for leaching to ground water. A review of available pesticide monitoring data suggests that many compounds given moderate or high leaching potentials have not been tested for in ground water and the presence of pesticides in Pennsylvania's ground water may be underreported. Monitoring data do not exist for more than two-thirds of the pesticide compounds currently used in agricultural, carbonate areas of Pennsylvania. Knowledge of processes that govern fate and transport of pesticides is needed to facilitate development of effective pesticide best-management practices. In addition to comprehensive monitoring for pesticides and pesticide degradation products in ground water downgradient of areas of pesticide use, improved (1) characterization of unsaturated flow and transport through regolith mantled carbonate rocks, (2) estimates of pesticide degradation rates, (3) understanding of soil-property controls on pesticide movement, and (4) management models developed from process-oriented research would aid in understanding the processes.

Hydrogeologic aspects of the Knippa Gap area in eastern Uvalde and western Medina counties, Texas

USGS Publications Warehouse

Lambert, Rebecca B.; Clark, Allan K.; Pedraza, Diana E.; Morris, Robert R.

2014-01-01

The Edwards aquifer is the primary source of potable water for the San Antonio area in south-central Texas. The Knippa Gap area is a structural low (trough) postulated to channel or restrict flow in the Edwards aquifer in eastern Uvalde and western Medina Counties, Tex. To better understand the function of the Knippa Gap, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, developed the first detailed surficial geologic map of the Knippa Gap area with data and information obtained from previous investigations and field observations. A simplified version of the detailed geologic map depicting the hydrologic units, faulting, and structural dips of the Knippa Gap area is provided in this fact sheet. The map shows that groundwater flow in the Edwards aquifer is influenced by the Balcones Fault Zone, a structurally complex area of the aquifer that contains relay ramps that have formed in extensional fault systems and allowed for deformational changes along fault blocks. Faulting in southeast Uvalde and southwest Medina Counties has produced relay-ramp structures that dip downgradient to the structural low (trough) of the Knippa Gap.

Filtration of Pathogenic Parasites Using Surfactant-Modified Zeolites

NASA Astrophysics Data System (ADS)

Lehner, T.; Schulze-Makuch, D.; Bowman, R.

2003-12-01

Migration of pathogenic microorganisms, specifically Cryptosporidium parvum and Giardia lamblia, in groundwater due to sewage effluent and mismanaged wastewater has become an increased concern for human health in many regions. Cryptosporididosis and Giardiasis produces moderate to severe intestinal illness for many weeks and is a serious threat for immunodeficient persons. Previous studies by Schulze-Makuch et al. (2002) indicated that surfactant-modified zeolites (SMZ) removed all of the bacteria and most viruses in laboratory experiments. This study focuses on the efficiency of the SMZ to prevent migration of the protozoan spores in groundwater. Adsorption of the spores involves interactions between the surface properties of the spores and the SMZ. The efficiency of removal is tested simulating natural conditions. Laboratory experiments are conducted in a plexiglass model aquifer and pathogen removal is measured by taking water samples from strategically placed piezometers in the model. Since C. parvum and G. lamblia are hazardous to humans and move primarily in spore state through groundwater, polystyrene microspheres of similar sizes and Bacillus subtilis, a sporulating bacterium, are used as analogues for the protozoa. Preliminary results show a significant decrease in concentration of the B. subtilis spores down-gradient of the barrier.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, J; Walt Kubilius, W; Thomas Kmetz, T

Resource Conservation and Recovery Act (RCRA) requirements for hazardous waste facilities include 30 years of post-closure monitoring. The use of an objective-based monitoring strategy allows for a significant reduction in the amount of groundwater monitoring required, as the groundwater remediation transitions from an active biosparging system to monitored natural attenuation. The lifecycle of groundwater activities at the landfill has progressed from detection monitoring and plume characterization, to active groundwater remediation, and now to monitored natural attenuation and postclosure monitoring. Thus, the objectives of the groundwater monitoring have changed accordingly. Characterization monitoring evaluated what biogeochemical natural attenuation processes were occurring andmore » determined that elevated levels of radium were naturally occurring. Process monitoring of the biosparging system required comprehensive sampling network up- and down-gradient of the horizontal wells to verify its effectiveness. Currently, the scope of monitoring and reporting can be significantly reduced as the objective is to demonstrate that the alternate concentration limits (ACL) are being met at the point of compliance wells and the maximum contaminant level (MCL) is being met at the surface water point of exposure. The proposed reduction is estimated to save about $2M over the course of the remaining 25 years of postclosure monitoring.« less

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, R. L.; Lawrence, B. L.

2011-06-09

The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the ERDF and report leachate results in fulfillment of the requirements specified in the ERDF ROD2 and the ERDF Amended ROD (EPA 1999). The overall objective of the groundwater monitoring program is to determine whether ERDF has impacted the groundwater. This objective is complicated by the fact that the ERDF is situated downgradient of the numerous groundwater contamination plumes originating from the 200 West Area.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Raymond H.; Stone, James; Truax, Ryan

Batch tests, column tests, and predictive reactive transport modeling can be done before ISR begins as part of the decision making/permitting process by bracketing possible post-restoration conditions; Help address stakeholder concerns; The best predictions require actual restored groundwater in contact with the downgradient solid phase; Resulting modeling provides a range of natural attenuation rates and assists with designing the best locations and time frames for continued monitoring; Field pilot tests are the best field-scale data and can provide the best model input and calibration data

Modeling soil moisture processes and recharge under a melting snowpack

USGS Publications Warehouse

Flint, A.L.; Flint, L.E.; Dettinger, M.D.

2008-01-01

Recharge into granitic bedrock under a melting snowpack is being investigated as part of a study designed to understand hydrologic processes involving snow at Yosemite National Park in the Sierra Nevada Mountains of California. Snowpack measurements, accompanied by water content and matric potential measurements of the soil under the snowpack, allowed for estimates of infiltration into the soil during snowmelt and percolation into the bedrock. During portions of the snowmelt period, infiltration rates into the soil exceeded the permeability of the bedrock and caused ponding to be sustained at the soil-bedrock interface. During a 5-d period with little measured snowmelt, drainage of the ponded water into the underlying fractured granitic bedrock was estimated to be 1.6 cm d?1, which is used as an estimate of bedrock permeability. The numerical simulator TOUGH2 was used to reproduce the field data and evaluate the potential for vertical flow into the fractured bedrock or lateral flow at the bedrock-soil interface. During most of the snowmelt season, the snowmelt rates were near or below the bedrock permeability. The field data and model results support the notion that snowmelt on the shallow soil overlying low permeability bedrock becomes direct infiltration unless the snowmelt rate greatly exceeds the bedrock permeability. Late in the season, melt rates are double that of the bedrock permeability (although only for a few days) and may tend to move laterally at the soil-bedrock interface downgradient and contribute directly to streamflow. ?? Soil Science Society of America.

Quality-Assurance Plan for Water-Quality Activities in the USGS Ohio Water Science Center

USGS Publications Warehouse

Francy, Donna S.; Shaffer, Kimberly H.

2008-01-01

In accordance with guidelines set forth by the Office of Water Quality in the Water Resources Discipline of the U.S. Geological Survey, a quality-assurance plan has been written for use by the Ohio Water Science Center in conducting water-quality activities. This quality-assurance plan documents the standards, policies, and procedures used by the Ohio Water Science Center for activities related to the collection, processing, storage, analysis, and publication of water-quality data. The policies and procedures documented in this quality-assurance plan for water-quality activities are meant to complement the Ohio Water Science Center quality-assurance plans for water-quality monitors, the microbiology laboratory, and surface-water and ground-water activities.

Approach to the vadose zone monitoring in hazardous and solid waste disposal facilities

NASA Astrophysics Data System (ADS)

Twardowska, Irena

2004-03-01

In the solid waste (SW)disposal sites, in particular at the unlined facilities, at the remediated or newly-constructed units equipped with novel protective/reactive permeable barriers or at lined facilities with leachate collection systems that are prone to failure, the vadose zone monitoring should comprise besides the natural soil layer beneath the landfill, also the anthropogenic vadose zone, i.e. the waste layer and pore solutions in the landfill. The vadose zone screening along the vertical profile of SW facilities with use of direct invasive soil-core and soil-pore liquid techniques shows vertical downward redistribution of inorganic (macroconstituents and heavy metals) and organic (PAHs) contaminant loads in water infiltrating through the waste layer. These loads can make ground water down-gradient of the dump unfit for any use. To avoid damage of protective/reactive permeable barriers and liners, an installation of stationary monitoring systems along the waste layer profile during the construction of a landfill, which are amenable to generate accurate data and information in a near-real time should be considered including:(i) permanent samplers of pore solution, with a periodic pump-induced transport of collected solution to the surface, preferably with instant field measurements;(ii)chemical sensors with continuous registration of critical parameters. These techniques would definitely provide an early alert in case when the chemical composition of pore solution percolating downward the waste profile shows unfavorable transformations, which indicate an excessive contaminant load approaching ground water. The problems concerning invasive and stationary monitoring of the vadose zone in SW disposal facilities will be discussed at the background of results of monitoring data and properties of permeable protective/reactive barriers considered for use.

The transport dynamics of chloride and sodium in a ladder fen during a continuous wastewater polishing experiment

NASA Astrophysics Data System (ADS)

McCarter, Colin P. R.; Price, Jonathan S.

2017-06-01

Ladder fen peatlands have excellent potential for wastewater polishing as they naturally contain both open water (pools) and subsurface (peat) treatment landforms; however, there is a poor understanding of solute transport in ladder fens with and without the increased hydrological load imposed by wastewater discharge. To better understand solute transport in ladder fens under wastewater polishing conditions a continuous solute (NaCl) tracer experiment (38 m3 day-1 of water, chloride - 47.2 mg L-1, and sodium - 25.3 mg L-1) was conducted during the summer of 2014 (day of year 192-243) in a small ladder fen in the James Bay Lowland. The transmissivity distribution and effective porosity (average 0.5) of the peat ribs were determined through repeated bail tests and the drainable porosity of 18 peat cores at -100 mb, respectively. Water samples were taken at least every 7 days to capture the solute (sodium and chloride) plumes. Both solute plumes never reached the site outflow (∼250 m downgradient) and displayed complex plume morphology, typically following the patterns of higher hydraulic conductivity within the upper 0.1 m of the saturated peat, rather than the microtopography. Based on the 50% breakthrough isotherms, sodium and chloride were transported at an average solute velocity of 1.9 and 1.1 m day-1, respectively (average linear groundwater velocity = 2.1 m day-1); thus, the solutes were retarded by a factor of 2.1 and 1.2 for sodium and chloride, respectively. Due to the inherent retardation of solutes into inactive pores and relatively high solute residence times, this study demonstrates the potential for wastewater polishing in ladder fens.

Assessing the Use of Dry Wells as a Tool for Stormwater Management and Groundwater Recharge in Urban Areas

NASA Astrophysics Data System (ADS)

Edwards, E.; Harter, T.; Fogg, G. E.; Washburn, B.; Bryson, R.; Meirovitz, C.; Fawcett, J.; Kretsinger Grabert, V. J.; Bowles, C.; Carr, M.; Nelson, C.

2014-12-01

Dry wells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas comprised primarily of impermeable surfaces or low permeability soils. Stormwater runoff that would otherwise be routed to streams or drains in urban areas is used as a source of aquifer recharge. However, the potential for groundwater contamination caused by urban runoff bypassing surface soil filtration has prevented more widespread use of dry wells as a recharge mechanism. We present the results of a literature survey to assess the potential of dry wells for safe stormwater recharge. Dry wells have been inculpated in groundwater contamination events, although accusations were typically not backed by scientific data. In 1989 groundwater in Modesto, CA, was contaminated with tetrachloroethylene from a dry cleaning facility. The city had been using dry wells to manage stormwater for more than 50 years without detrimental impacts before the contamination. A USGS monitoring study proved that the contamination was from sewer system leakage, and did not involve the dry wells. Some areas of the country have used dry wells with positive results. The Underground Injection Control system (UICs) study in Portland, OR, has been active for ten years, and currently operates over 9,000 UICs. Initially, a ten foot separation distance was enforced between the seasonal high water table and the bottom perforation of the UIC; however, due to monitoring and modeling results that indicate the protectiveness of groundwater, this distance has been reduced to zero feet. Future work will include a comparative pilot study involving a residential and an industrial site in Elk Grove, CA. The study will use modeling tools to assess the recharge potential and groundwater protectiveness of dry wells. Both sites are outfitted with four monitoring wells each: an upgradient monitoring well, two downgradient monitoring wells, and a vadose zone monitoring well. The results of water quality sampling will determine the contaminants of interest, and a model of the fate and transport of these contaminants in the vadose zone will be coupled with hydraulic models to estimate the response of the hydrogeologic system to dry well recharge, with the goal of creating a tool that can be used to evaluate future dry well locations.

Field investigation of the quality of fresh and aged leachates from selected landfills receiving e-waste in an arid climate.

PubMed

Kiddee, Peeranart; Naidu, Ravi; Wong, Ming H; Hearn, Laurence; Muller, Jochen F

2014-11-01

The management of electronic waste (e-waste) is a serious problem worldwide and much of it is landfilled. A survey of four selected landfills in an arid region of South Australia was conducted to determine the proportion of e-waste in municipal waste and the properties of each landfill site. Leachate and groundwater samples were collected upgradient and downgradient of the landfills for analysis of polybrominated diphenyl ethers (PBDEs) and 14 metals and metalloids, including Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sb, V and Zn. Our data demonstrate that the selected landfills in South Australia continue to receive municipal waste containing in excess of 6%, or 25,000 tonnes per year, of e-waste. The leachates and groundwater collected from the landfills contained significantly elevated concentrations of Pb with the highest concentration in groundwater of 38 μg/l, almost four times higher than the Australian drinking water guideline of 10 μg/l. The presence of PBDEs was detected in both leachate and groundwater samples. Total PBDEs values of 2.13-59.75 ng/l in leachate samples were 10 times higher than in groundwater samples, which recorded a range of 0.41-6.53 ng/l at all sites. Moreover, the concentrations of metals and metalloids in sampled groundwater contained elevated levels of Al, As, Fe, Ni and Pb that exceeded Australian drinking water guideline values. For these reasons potential leaching of these contaminants is of concern and while difficult to attribute elevated contaminant levels to e-waste, we do not recommend continued disposal of e-waste in old landfills that were not originally designed to contain leachates. The survey also revealed temporal variation in the electrical conductivity and concentrations of As, Cd and Pb present in leachates of landfills in arid Mediterranean climates. These results are consistent with the marked variations in rainfall patterns observed for such climates. The solute concentration (EC and other ions including As, Cd and Pb) declines in the leachates during wet winter months (June to September), in contrast to tropical countries where such changes are observed during wet summer months. Copyright © 2014 Elsevier Ltd. All rights reserved.

Simulation of ground-water flow and areas contributing recharge to extraction wells at the Drake Chemical Superfund Site, City of Lock Haven and Castanea Township, Clinton County, Pennsylvania

USGS Publications Warehouse

Schreffler, Curtis L.

2006-01-01

Extensive remediation of the Drake Chemical Superfund Site has been ongoing since 1983. Contaminated soils were excavated and incinerated on site between 1996 and 1999. After 1999, remedial efforts focused on contaminated ground water. A ground-water remediation system was started in November 2000. The source area of the contaminated ground water was assumed to be the zone 1 area on the Drake Chemical site. The remedial system was designed to capture ground water migrating from zone 1. Also, the remediation system was designed to pump and treat the water in an anoxic environment and re-infiltrate the treated water underground through an infiltration gallery that is hydrologically downgradient of the extraction wells. A numerical ground-water flow model of the surrounding region was constructed to simulate the areas contributing recharge to remedial extraction wells installed on the Drake Chemical site. The three-dimensional numerical flow model was calibrated using the parameter-estimation process in MODFLOW-2000. The model included three layers that represented three poorly sorted alluvial sediment units that were characterized from geologic well and boring logs. Steady-state ground-water flow was simulated to estimate the areas contributing recharge to three extraction wells for three different pumping scenarios--all wells pumping at 2 gallons per minute, at approximately 5 gallons per minute, and at 8 gallons per minute. Simulation results showed the contributing areas to the three extraction wells encompassed 92 percent of zone 1 at a pumping rate of approximately 5 gallons per minute. The contributing areas did not include a very small area in the southwestern part of zone 1 when the three extraction wells were pumped at approximately 5 gallons per minute. Pumping from a fourth extraction well in that area was discontinued early in the operation of the remediation system because the ground water in that area met performance standards. The areas contributing recharge to the three extraction wells did encompass zone 1 at a pumping rate of 8 gallons per minute. At pumping rates of 2 gallons per minute, the contributing areas for the three extraction wells did not encompass zone 1.

Hydrogeochemical Investigation of the Standard Mine Vicinity, Upper Elk Creek Basin, Colorado

USGS Publications Warehouse

Manning, Andrew H.; Verplanck, Philip L.; Mast, M. Alisa; Wanty, Richard B.

2008-01-01

Ground- and surface-water samples were collected in the vicinity of the Standard Mine in west-central Colorado in order to characterize the local ground-water flow system, determine metal concentrations in local ground water, and better understand factors controlling the discharge of metal-rich waters from the mine. The sampling program included a one-time sampling of springs, mine adits, and exploration pits in Elk Basin and Redwell Basin; repeated sampling throughout one year of Standard Mine Level 1 discharge and Elk Creek near its confluence with Coal Creek; and a one-time sampling of underground sites in Levels 3 and 5 of the Standard Mine. Samples were analyzed for major ions and trace elements, stable isotopes of hydrogen (2H/1H) and oxygen (18O/16O), strontium isotopes, and tritium and dissolved noble gases (including helium isotopes) for tritium/helium-3 age dating. No clear correlations were observed between natural ground-water discharge locations and map-scale faults and lithology. Surface observations and the location of ground-water discharge suggest that simple topography, rather than large-scale geologic features, primarily controls the occurrence and flow of shallow ground water in Elk Basin. Discrete inflows from cross faults or other features were not observed in Levels 3 and 5 of the Standard Mine. Instead, water entered the mine as relatively persistent dripping from gouge and breccia within the Standard fault, which both tunnels follow. Therefore, the Standard fault itself is probably the main pathway of ground-water flow from the shallow subsurface to the mine workings. Low pH (as low as 3.2) and elevated concentrations of zinc, lead, cadmium, copper, and manganese (commonly exceeding water-quality standards for Elk Creek) were measured in samples located within or immediately downgradient of areas where sulfides are abundant, including the Standard fault, the Elk Lode portal, and the breccia pipe in Redwell Basin. Concentrations of these metals were typically low and pH values were circumneutral at surrounding locations. Metal concentrations in samples collected from underground workings in the Standard Mine were also generally higher than in samples collected at aboveground sites located outside of sulfide-rich areas. Metal concentrations in discharge from the Level 1 tunnel were among the highest measured in Elk Basin. All of these observations suggest that sulfide-rich mineralized rock is the primary control on dissolved metal concentrations and pH in ground water in the Standard Mine vicinity. Waste-rock piles apparently exert another major control on metal concentrations and pH; the lowest pH and highest metal concentrations typically are found in discharge from waste-rock piles. Concentrations of several chemical constituents along with strontium isotope data indicate that none of the sampled waters could have been the primary source of metals in discharge from Level 1. Therefore, this study did not identify the primary source location for metals in Level 1 discharge. Possible sources must be located below Levels 3 and 5 or farther back into the mountainside than the ends of Levels 3 and 5. Apparent tritium/helium-3 ground-water ages ranged from 0 to 9 yr, and a considerable majority were <1 yr. Tritium data and computed initial tritium values (measured tritium plus measured tritiogenic helium-3) suggest that much of the ground water in the Standard Mine vicinity was weeks to months old rather than years old. Tritium, d2H, and d18O data from water entering into and discharging from the Standard Mine displayed spatial and temporal patterns indicating that these tracers were influenced by seasonal variations in their concentration in precipitation. The tracer data therefore suggest that ground water entering into and discharging from the Standard Mine was largely composed of water <1 yr old. Pronounced seasonal variations in geochemistry in Level 1 discharge also are consistent with short r

Development of innovative computer software to facilitate the setup and computation of water quality index.

PubMed

Nabizadeh, Ramin; Valadi Amin, Maryam; Alimohammadi, Mahmood; Naddafi, Kazem; Mahvi, Amir Hossein; Yousefzadeh, Samira

2013-04-26

Developing a water quality index which is used to convert the water quality dataset into a single number is the most important task of most water quality monitoring programmes. As the water quality index setup is based on different local obstacles, it is not feasible to introduce a definite water quality index to reveal the water quality level. In this study, an innovative software application, the Iranian Water Quality Index Software (IWQIS), is presented in order to facilitate calculation of a water quality index based on dynamic weight factors, which will help users to compute the water quality index in cases where some parameters are missing from the datasets. A dataset containing 735 water samples of drinking water quality in different parts of the country was used to show the performance of this software using different criteria parameters. The software proved to be an efficient tool to facilitate the setup of water quality indices based on flexible use of variables and water quality databases.

Water resources and the hydrologic effects of coal mining in Washington County, Pennsylvania

USGS Publications Warehouse

Williams, Donald R.; Felbinger, John K.; Squillace, Paul J.

1993-01-01

Washington County occupies an area of 864 square miles in southwestern Pennsylvania and lies within the Pittsburgh Plateaus Section of the Appalachian Plateaus physiographic province. About 69 percent of the county population is served by public water-supply systems, and the Monongahela River is the source for 78 percent of the public-supply systems. The remaining 31 percent of the population depends on wells, springs, and cisterns for its domestic water supply. The sedimentary rocks of Pennsylvanian and Permian age that underlie the county include sandstone, siltstone, limestone, shale, and coal. The mean reported yield of bedrock wells ranges from 8.8 gallons per minute in the Pittsburgh .Formation to 46 gallons per minute in the Casselman Formation. Annual water-level fluctuations usually range from less than 3 ft (feet) beneath a valley to about 16 ft beneath a hilltop. Average hydraulic conductivity ranges from 0.01 to 18 ft per day. Water-level fluctuations and aquifer-test results suggest that most ground water circulates within 150 ft of land surface. A three-dimensional computer flow-model analysis indicates 96 percent of the total ground-water recharge remains in the upper 80 to 110 ft of bedrock (shallow aquifer system). The regional flow system (more than 250ft deep in the main valley) receives less than 0.1 percent of the total ground-water recharge from the Brush Run basin. The predominance of the shallow aquifer system is substantiated by driller's reports, which show almost all water bearing zones are less than 150ft below land surface. The modeling of an unmined basin showed that the hydrologic factors that govern regional groundwater flow can differ widely spatially but have little effect on the shallow aquifers that supply water to most domestic wells. However, the shallow aquifers are sensitive to hydrologic factors within this shallow aquifer system (such as ground-water recharge, hydraulic conductivity of the streamaquifer interface, and hydraulic conductivity of the aquifer). A vertical fracture zone would probably increase ground-water availability within the zone and would probably result in a lower head in the shallow aquifers in an upland draw area and an increased head in a valley. l Streams in the northern and western parts of the county drain to the Ohio River and streams in the eastern and southern parts of the county drain to the Monongahela River. The computed 7-day, 10-year low-flow frequencies for the surface-water sites ranged from 0.0 to 55 x 10-3 cubic feet per second per square mile. The lowest low-flow discharges per square mile were in the south-central and southwestern parts of the county. The highest low-flow discharges per square mile were in the eastern and northern parts of the county. The annual water loss at five gaged streams ranged from 52 to 75 percent of the total precipitation. The loss resulted from evaporation, transpiration, diversion, mines, ground-water outflow from the system, and plant and animal consumption. The major ground-water-quality problems are elevated concentrations of iron, manganese, and dissolved solids, and very hard water. Minor groundwater-quality problems include elevated concentrations of fluoride, chloride, and sulfate. Downgradient along the ground-water flow path, principal ions change from mostly calcium, magnesium, sulfate, and bicarbonate to sodium and chloride. Dissolyed-solids concentrations generally increase with residence time .. Elevated concentrations of sulfate and total dissolved solids were common at the surface-water sites in the northern and eastern parts of the county where most of the active and abandohed coal mines are located and where acid mine drainage is most prevalent. However, measured alkalinity at most of the surface-water sites ranged from 86 to 345 milligrams per liter, indicating that these streams would have a neutralizing effect on most inflows of acid mine drainage. The model of the hypothetically mined Brush Run basin shows that the vertical hydraulic conductivity (either existing or induced by mine subsidence) between the shallow ground-water system and the mine, and the depth to the mine are critical controls on the amount of ground water entering the mine. When the vertical hydraulic conductivity was increased by a factor of four for a mine about 250 ft deep in the main valley, inflow to the mine increased almost by the same factor. The model also shows that increasing the depth to a mine by 200 ft (mine about 450 ft deep in main valley) would cause mine inflow to decrease one order of magnitude. Comparisons between stream discharges during low base-flow conditions in a mined basin (Daniels Run) and an unrnined basin (Brush Run) indicated that the deep mining did not substantially lower streamflow. Although streamflow decreased and, at times, completely disappeared in the middle and lower parts of Daniels Run basin, it reappeared again downstream as ground-water discharge and was part of the flow at the mouth of Daniels Run. Comparison of the water-quality characteristics of the two basins showed that concentrations of dissolved solids, sulfate, sodium, chloride, fluoride, and manganese were greater in the mined basin than in the unmined basin. The pH and iron concentrations were similar in both basins.

Status and understanding of groundwater quality in the Santa Clara River Valley, 2007-California GAMA Priority Basin Project

USGS Publications Warehouse

Burton, Carmen A.; Montrella, Joseph; Landon, Matthew K.; Belitz, Kenneth

2011-01-01

Groundwater quality in the approximately 460-square-mile Santa Clara River Valley study unit was investigated from April through June 2007 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project is conducted by the U.S. Geological Survey (USGS) in collaboration with the California State Water Resources Control Board and the Lawrence Livermore National Laboratory. The Santa Clara River Valley study unit contains eight groundwater basins located in Ventura and Los Angeles Counties and is within the Transverse and Selected Peninsular Ranges hydrogeologic province. The Santa Clara River Valley study unit was designed to provide a spatially unbiased assessment of the quality of untreated (raw) groundwater in the primary aquifer system. The assessment is based on water-quality and ancillary data collected in 2007 by the USGS from 42 wells on a spatially distributed grid, and on water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer system was defined as that part of the aquifer system corresponding to the perforation intervals of wells listed in the CDPH database for the Santa Clara River Valley study unit. The quality of groundwater in the primary aquifer system may differ from that in shallow or deep water-bearing zones; for example, shallow groundwater may be more vulnerable to surficial contamination. Eleven additional wells were sampled by the USGS to improve understanding of factors affecting water quality.The status assessment of the quality of the groundwater used data from samples analyzed for anthropogenic constituents, such as volatile organic compounds (VOCs) and pesticides, as well as naturally occurring inorganic constituents, such as major ions and trace elements. The status assessment is intended to characterize the quality of untreated groundwater resources in the primary aquifers of the Santa Clara River Valley study unit, not the quality of treated drinking water delivered to consumers. Relative-concentrations (sample concentration divided by health- or aesthetic-based benchmark concentration) were used for evaluating groundwater quality for those constituents that have Federal and (or) California benchmarks. A relative-concentration greater than 1.0 indicates a concentration greater than a benchmark. For organic and special interest constituents, relative-concentrations were classified as high (greater than 1.0); moderate (greater than 0.1 and less than or equal to 1.0); and low (less than or equal to 0.1). For inorganic constituents, relative-concentrations were classified as high (greater than 1.0); moderate (greater than 0.5 and less than or equal to 1.0); and low (less than or equal to 0.5). Aquifer-scale proportion was used as the primary metric in the status assessment for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the areal percentage of the primary aquifer system with relative-concentrations greater than 1.0. Moderate and low aquifer-scale proportions are defined as the areal percentage of the primary aquifer system with moderate and low relative-concentrations, respectively. Two statistical approaches, grid-based and spatially weighted, were used to evaluate aquifer-scale proportions for individual constituents and classes of constituents. Grid-based and spatially weighted estimates were comparable in the Santa Clara River Valley study unit (within 90 percent confidence intervals). The status assessment showed that inorganic constituents were more prevalent and relative-concentrations were higher than for organic constituents. For inorganic constituents with human-health benchmarks, relative-concentrations (of one or more constituents) were high in 21 percent of the primary aquifer system areally, moderate in 30 percent, and low or not detected in 49 percent. Inorganic constituents with human-health benchmarks with high aquifer-scale proportions were nitrate (15 percent of the primary aquifer system), gross alpha radioactivity (14 percent), vanadium (3.4 percent), boron (3.2 percent), and arsenic (2.3 percent). For inorganic constituents with aesthetic benchmarks, relative-concentrations (of one or more constituents) were high in 54 percent of the primary aquifer system, moderate in 41 percent, and low or not detected in 4 percent. The inorganic constituents with aesthetic benchmarks with high aquifer-scale proportions were total dissolved solids (35 percent), sulfate (22 percent), manganese (38 percent), and iron (22 percent). In contrast, the results of the status assessment for organic constituents with human-health benchmarks showed that relative-concentrations were high in 0 percent (not detected above benchmarks) of the primary aquifer system, moderate in 2.4 percent, and low or not detected in 97 percent. Relative-concentrations of the special interest constituent, perchlorate, were moderate in 12 percent of the primary aquifer system and low or not detected in 88 percent. Relative-concentrations of two VOCs-carbon tetrachloride and trichloroethene (TCE)-were moderate in 2.4 percent of the primary aquifer system. One VOC-chloroform (water disinfection byproduct)-was detected in more than 10 percent of the primary aquifer system but at low relative-concentrations. Of the 88 VOCs and gasoline oxygenates analyzed, 71 were not detected. Pesticides were low or not detected in 100 percent of the primary aquifer system. Of the 118 pesticides and pesticide degradates analyzed, 13 were detected and 5 of those had human-health benchmarks. Two of these five pesticides-simazine and atrazine-were detected in more than 10 percent of the primary aquifer system. The second component of this study, the understanding assessment, was to identify the natural and human factors that affect groundwater quality on the basis of the evaluation of land use, physical characteristics of the wells, and geochemical conditions of the aquifer. Results from these analyses are used to explain the occurrence and distribution of selected constituents in the primary aquifer system of the Santa Clara River Valley study unit. The understanding assessment indicated that water quality varied spatially primarily in relation to depth, groundwater age, reduction-oxidation conditions, pH, and location in the regional groundwater flow system. High and moderate relative-concentrations of nitrate and low relative-concentrations of pesticides were correlated with shallow depths to top-of-perforation, and with high dissolved oxygen. Groundwater of modern and mixed ages had higher nitrate than pre-modern-age groundwater. Decreases in concentrations of total dissolved solids (TDS) and sulfate were correlated with increases in pH. This relationship probably indicates relations of these constituents with increasing depth across most of the Santa Clara River Valley study unit. Previous studies have indicated multiple sources of high concentrations of TDS and sulfate and multiple geochemical processes affecting these constituents in the Santa Clara River Valley study unit. Manganese and iron concentrations were highest in pre-modern-age groundwater at depth and in the downgradient area of the Santa Clara River Valley study unit (closest to the coastline), indicating the prevalence of reducing groundwater conditions in these aquifer zones.

What's in Your Water? An Educator's Guide to Water Quality.

ERIC Educational Resources Information Center

Constabile, Kerry, Comp.; Craig, Heidi, Comp.; O'Laughlin, Laura, Comp.; Reiss, Anne Bei, Comp.; Spencer, Liz, Comp.

This guide provides basic information on the Clean Water Act, watersheds, and testing for water quality, and presents four science lesson plans on water quality. Activities include: (1) "Introduction to Water Quality"; (2) "Chemical Water Quality Testing"; (3) "Biological Water Quality Testing"; and (4) "What Can We Do?" (YDS)

Quality-Assurance Plan for Water-Quality Activities of the U.S. Geological Survey Montana Water Science Center

USGS Publications Warehouse

Lambing, John H.

2006-01-01

In accordance with guidelines set forth by the Office of Water Quality in the Water Resources Discipline of the U.S. Geological Survey (USGS), a quality-assurance plan has been created for use by the USGS Montana Water Science Center in conducting water-quality activities. This quality-assurance plan documents the standards, policies, and procedures used by the USGS Montana Water Science Center for activities related to the collection, processing, storage, analysis, and publication of water-quality data. The policies and procedures presented in this quality-assurance plan for water-quality activities complement the quality-assurance plans for surface-water and ground-water activities and suspended-sediment analysis.

Upper Illinois River basin

USGS Publications Warehouse

Friedel, Michael J.

1998-01-01

During the past 25 years, industry and government made large financial investments that resulted in better water quality across the Nation; however, many water-quality concerns remain. Following a 1986 pilot project, the U.S. Geological Survey began implementation of the National Water-Quality Assessment (NAWQA) Program in 1991. This program differs from other national water-quality assessment studies in that the NAWQA integrates monitoring of surface- and ground-water quality with the study of aquatic ecosystems. The goals of the NAWQA Program are to (1) describe current water-quality conditions for a large part of the Nation's freshwater streams and aquifers (water-bearing sediments and rocks), (2) describe how water quality is changing over time, and (3) improve our understanding of the primary natural and human factors affecting water quality.The Upper Illinois River Basin National Water- Quality Assessment (NAWQA) study will increase the scientific understanding of surface- and ground-water quality and the factors that affect water quality in the basin. The study also will provide information needed by water-resource managers to implement effective water-quality management actions and evaluate long-term changes in water quality.

Long-term natural attenuation of carbon and nitrogen within a groundwater plume after removal of the treated wastewater source

USGS Publications Warehouse

Repert, D.A.; Barber, L.B.; Hess, K.M.; Keefe, S.H.; Kent, D.B.; LeBlanc, D.R.; Smith, R.L.

2006-01-01

Disposal of treated wastewater for more than 60 years onto infiltration beds on Cape Cod, Massachusetts produced a groundwater contaminant plume greater than 6 km long in a surficial sand and gravel aquifer. In December 1995 the wastewater disposal ceased. A long-term, continuous study was conducted to characterize the post-cessation attenuation of the plume from the source to 0.6 km downgradient. Concentrations and total pools of mobile constituents, such as boron and nitrate, steadily decreased within 1-4 years along the transect. Dissolved organic carbon loads also decreased, but to a lesser extent, particularly downgradient of the infiltration beds. After 4 years, concentrations and pools of carbon and nitrogen in groundwater were relatively constant with time and distance, but substantially elevated above background. The contaminant plume core remained anoxic for the entire 10-year study period; temporal patterns of integrated oxygen deficit decreased slowly at all sites. In 2004, substantial amounts of total dissolved carbon (7 mol C m-2) and fixed (dissolved plus sorbed) inorganic nitrogen (0.5 mol N m-2) were still present in a 28-m vertical interval at the disposal site. Sorbed constituents have contributed substantially to the dissolved carbon and nitrogen pools and are responsible for the long-term persistence of the contaminant plume. Natural aquifer restoration at the discharge location will take at least several decades, even though groundwater flow rates and the potential for contaminant flushing are relatively high.

Toxicity of organic chemical pollution in groundwater downgradient of a landfill (Grindsted, Denmark)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baun, A.; Jensen, S.D.; Bjerg, P.L.

2000-05-01

The aim of the present study was to describe the occurrence and distribution of toxicity related to organic chemical contaminants in the leachate plume downgradient of the Grindsted Landfill (Denmark). A total of 27 groundwater samples were preconcentrated by solid-phase extraction (SPE) using XAD-2 as the resin material. This treatment effectively eliminated sample matrix toxicity caused by inorganic salts and natural organic compounds and produced an aqueous concentrate of the nonvolatile chemical contaminants. The SPE extracts were tested in a battery of standardized short-term aquatic toxicity tests with luminescent bacteria (Vibrio fischeri), algae (Selenastrum capricornutum), and crustaceans (Daphnia magna). Additionalmore » genotoxicity tests were made using the umuC test (Salmonella typhimurium). Biotests with algae and luminescent bacteria were the most sensitive tests. On the basis of results with these two bioassays, it was concluded that SPE extracts of groundwater collected close to the landfill were toxic. The toxicity decreased with the distance from the landfill. At distances greater than 80 m from the border of the landfill, the groundwater toxicity was not significantly different from the background toxicity. SPE extracts were not toxic to Daphnia, and no genotoxicity was observed in the umuC test. The overall findings indicate that a battery of biotests applied on preconcentrated groundwater samples can be a useful tool for toxicity characterization and hazard ranking of groundwater polluted with complex chemical mixtures, such as landfill leachates.« less

Partitioning microbial respiration between jet fuel and native organic matter in an organic-rich long time-contaminated aquifer.

PubMed

Bugna, G C; Chanton, J P; Stauffer, T B; MacIntyre, W G; Libelo, E L

2005-07-01

The relative importance of jet fuel biodegradation relative to the respiration of natural organic matter in a contaminated organic-rich aquifer underlying a fire training area at Tyndall Air Force Base, Florida, USA was determined with isotopic measurements. Thirteen wells were sampled and analyzed for BTX (benzene, toluene, xylene), dissolved inorganic carbon (DIC) and CH4 concentrations, and delta13C and 14C of DIC. Results range from non-detectable to 3790 ppb, 1.4-24 mM, 0.2-776 microM, +5.8 per thousand to -22 per thousand, and from 52 to 99 pmc, respectively. Residual fuel was confined to two center wells underlying the fire training area. DIC and CH4 concentrations were elevated down-gradient of the contamination, but also at sites that were not in the apparent flow path of the contaminated groundwater. DIC exhibited greatest delta13C enrichment at highest DIC and CH4 concentrations indicating that CH4 production was an important respiration mode. Radiocarbon-depleted DIC was observed at sites with high hydrocarbon concentrations and down-gradient of the site. The results indicate that while natural attenuation was not rapidly reducing the quantity of free product overlying the aquifer at the site of contamination, it was at least constraining its flow away from the spill site. Apparently under the conditions of this study, BTX was degraded as rapidly as it was dissolved.

Water quality assessment with hierarchical cluster analysis based on Mahalanobis distance.

PubMed

Du, Xiangjun; Shao, Fengjing; Wu, Shunyao; Zhang, Hanlin; Xu, Si

2017-07-01

Water quality assessment is crucial for assessment of marine eutrophication, prediction of harmful algal blooms, and environment protection. Previous studies have developed many numeric modeling methods and data driven approaches for water quality assessment. The cluster analysis, an approach widely used for grouping data, has also been employed. However, there are complex correlations between water quality variables, which play important roles in water quality assessment but have always been overlooked. In this paper, we analyze correlations between water quality variables and propose an alternative method for water quality assessment with hierarchical cluster analysis based on Mahalanobis distance. Further, we cluster water quality data collected form coastal water of Bohai Sea and North Yellow Sea of China, and apply clustering results to evaluate its water quality. To evaluate the validity, we also cluster the water quality data with cluster analysis based on Euclidean distance, which are widely adopted by previous studies. The results show that our method is more suitable for water quality assessment with many correlated water quality variables. To our knowledge, it is the first attempt to apply Mahalanobis distance for coastal water quality assessment.

Development of innovative computer software to facilitate the setup and computation of water quality index

PubMed Central

2013-01-01

Background Developing a water quality index which is used to convert the water quality dataset into a single number is the most important task of most water quality monitoring programmes. As the water quality index setup is based on different local obstacles, it is not feasible to introduce a definite water quality index to reveal the water quality level. Findings In this study, an innovative software application, the Iranian Water Quality Index Software (IWQIS), is presented in order to facilitate calculation of a water quality index based on dynamic weight factors, which will help users to compute the water quality index in cases where some parameters are missing from the datasets. Conclusion A dataset containing 735 water samples of drinking water quality in different parts of the country was used to show the performance of this software using different criteria parameters. The software proved to be an efficient tool to facilitate the setup of water quality indices based on flexible use of variables and water quality databases. PMID:24499556

Water Quality Assessment for Deep-water Channel area of Guangzhou Port based on the Comprehensive Water Quality Identification Index Method

NASA Astrophysics Data System (ADS)

Chen, Yi

2018-03-01

The comprehensive water quality identification index method is able to assess the general water quality situation comprehensively and represent the water quality classification; water environment functional zone achieves pollution level and standard objectively and systematically. This paper selects 3 representative zones along deep-water channel of Guangzhou port and applies comprehensive water quality identification index method to calculate sea water quality monitoring data for different selected zones from year 2006 to 2014, in order to investigate the temporal variation of water quality along deep-water channel of Guangzhou port. The comprehensive water quality level from north to south presents an increased trend, and the water quality of the three zones in 2014 is much better than in 2006. This paper puts forward environmental protection measurements and suggestions for Pearl River Estuary, provides data support and theoretical basis for studied sea area pollution prevention and control.

Plant Enhanced Bioremediation of Dissolved Toluene in Large Scale Column Setup

NASA Astrophysics Data System (ADS)

Basu, S.; Yadav, B. K.; Mathur, S.

2016-12-01

Hydrocarbons like BTEX compounds entering the soil-water system through anthropogenic activities can be long lasting sources of pollution, and thus, it is essential to look for remediation options that are environmentally benign. Bioremediation is a promising cost effective technique causing no harm to the contaminated ecosystem as compared to the traditional physicochemical methods. Natural microbes degrade contaminants from polluted soil water resources in bioremediation; however this process of natural bioremediation is quite slow under prevailing environmental conditions of a typical polluted site. Research has also proven that plants play an important role when it comes to accelerate the degradation rate cost-effectively in enhanced bioremediation technique. Thus in this study, fate and transport of dissolved toluene from a source zone to down-gradient receptors in a continuous soil-water plant system was investigated. For this, two sets of large scale column experiments were performed by connecting them with a treatment wetland having canna plants in first set and unplanted gravel bed in the second set. A continuous source of toluene contaminated water was supplied at the top of the column setups. A constant groundwater flow velocity of 0.625 cm/hr was maintained in the vertical direction. Free drainage was allowed at the bottom and a constant hydraulic head of 2.0 cm was maintained at the top boundary throughout the period of the experiments in both the cases. The observed microbial colonies using the plate counting method along with measured dissolved oxygen (DO) proved that the BTEX compound degraded aerobically at a faster rate in the first set. Plants played a positive role in enhancing biodegradation rate of the BTEX compound during its transport through the porous media. Finally the observed data of the column experiments were compared with the breakthrough curves obtained numerically solving the advection dispersion equation. The results of this research can be used to obtain vital information on framing the engineered bioremediation planning for contaminated sites.

Assessment of nitrification potential in ground water using short term, single-well injection experiments

USGS Publications Warehouse

Smith, R.L.; Baumgartner, L.K.; Miller, D.N.; Repert, D.A.; Böhlke, J.K.

2006-01-01

Nitrification was measured within a sand and gravel aquifer on Cape Cod, MA, using a series of single-well injection tests. The aquifer contained a wastewater-derived contaminant plume, the core of which was anoxic and contained ammonium. The study was conducted near the downgradient end of the ammonium zone, which was characterized by inversely trending vertical gradients of oxygen (270 to 0 μM) and ammonium (19 to 625 μM) and appeared to be a potentially active zone for nitrification. The tests were conducted by injecting a tracer solution (ambient ground water + added constituents) into selected locations within the gradients using multilevel samplers. After injection, the tracers moved by natural ground water flow and were sampled with time from the injection port. Rates of nitrification were determined from changes in nitrate and nitrite concentration relative to bromide. Initial tests were conducted with 15N-enriched ammonium; subsequent tests examined the effect of adding ammonium, nitrite, or oxygen above background concentrations and of adding difluoromethane, a nitrification inhibitor. In situ net nitrate production exceeded net nitrite production by 3- to 6- fold and production rates of both decreased in the presence of difluoromethane. Nitrification rates were 0.02–0.28 μmol (L aquifer)−1 h−1 with in situ oxygen concentrations and up to 0.81 μmol (L aquifer)−1 h−1 with non-limiting substrate concentrations. Geochemical considerations indicate that the rates derived from single-well injection tests yielded overestimates of in situ rates, possibly because the injections promoted small-scale mixing within a transport-limited reaction zone. Nonetheless, these tests were useful for characterizing ground water nitrification in situ and for comparing potential rates of activity when the tracer cloud included non-limiting ammonium and oxygen concentrations.

Reconnaissance of volatile organic compounds in the subsurface at Rutgers University, Busch Campus, Piscataway Township, New Jersey

USGS Publications Warehouse

dePaul, V.T.

1996-01-01

During 1991-92, the U.S. Geological Survey conducted a hydrogeologic reconnaissance at a site near the Rutgers University, Busch Campus, Chemical Engineering building, C-Wing. Results of analyses of the soil-gas samples, which were collected at 43 locations, indicated the presence of volatile organic compounds, primarily carbon tetrachloride, near the C-Wing building and about 550 feet downgradient from and southwest of the C-Wing building. Concentrations of the compound in soil-gas samples were highest (2.1 ug/L (micrograms per liter)) along the southwestern wall of the C-Wing building. Ground-water samples were collected at depths as great as 55 feet from five wells and piezometers near the C-Wing building. Samples collected along the southwestern wall of the building also contained the highest concentrations of volatile organic compounds. Concentrations of carbon tetrachloride in the ground-water samples ranged from < 0.35 ug/L to 3,400 ug/L, and concentrations of tetrachloro- ethylene ranged from < 0.28 ug/L to 85 ug/L. Ground-water samples collected at depths of 55 feet or more from two wells located on the Rutgers University Golf Course about 2,400 feet down- gradient from the C-Wing building contained concentrations of tetrachloroethylene as great as 17.7 ug/L. Water levels measured in six wells and six piezometers indicated that the general flow direction in the shallow part of the aquifer is to the southwest of the C-Wing building. An electrical-resistivity survey was conducted by azimuthal resistivity techniques. The results of the survey were consistent with field measurements, and the dominant vertical fractures near the Busch Campus trend northeast. An electromagnetic survey was ineffective as a result of cultural interferences and could not be used to determine the hydrogeologic characteristics of the site.

Geochemical evolution of groundwater salinity at basin scale: a case study from Datong basin, Northern China.

PubMed

Wu, Ya; Wang, Yanxin

2014-05-01

A hydrogeochemical investigation using integrated methods of stable isotopes ((18)O, (2)H), (87)Sr/(86)Sr ratios, Cl/Br ratios, chloride-mass balance, mass balance and hydrogeochemical modeling was conducted to interpret the geochemical evolution of groundwater salinity in Datong basin, northern China. The δ(2)H, δ(18)O ratios in precipitation exhibited a local meteoric water line of δ(2)H = 6.4 δ(18)O -5 (R(2) = 0.94), while those in groundwater suggested their meteoric origin in a historically colder climatic regime with a speculated recharge rate of less than 20.5 mm overall per year, in addition to recharge from a component of deep residual ancient lake water enriched with Br. According to the Sr isotope binary mixing model, the mixing of recharges from the Shentou karst springs (24%), the western margins (11%) and the eastern margins (65%) accounts for the groundwater from the deep aquifers of the down-gradient parts in the central basin is a possible mixing mechanism. In Datong, hydrolysis of silicate minerals is the most important hydrogeochemical process responsible for groundwater chemistry, in addition to dissolution of carbonate and evaporites. In the recharge areas, silicate chemical weathering is typically at the bisiallitization stage, while that in the central basin is mostly at the monosiallitization stage with limited evidence of being in equilibrium with gibbsite. Na exchange with bound Ca, Mg prevails at basin scale, and intensifies with groundwater salinity, while Ca, Mg exchange with bound Na locally occurs in the east pluvial and alluvial plains. Although groundwater salinity increases with the progress of water-rock/sediment interactions along the flow path, as a result of carbonate solubility control and continuous evapotranspiration, Na-HCO3 and Na-Cl-SO4 types of water are usually characterized respectively in the deep and the shallow aquifers of an inland basin with a silicate terrain in an arid climatic regime.

78 FR 20252 - Water Quality Standards; Withdrawal of Certain Federal Water Quality Criteria Applicable to...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-04

... aquatic life water quality criteria applicable to waters of New Jersey, Puerto Rico, and California's San Francisco Bay. In 1992, EPA promulgated the National Toxics Rule or NTR to establish numeric water quality... Water Quality Standards; Withdrawal of Certain Federal Water Quality Criteria Applicable to California...

Quality-assurance plan for water-quality activities in the U.S. Geological Survey Washington Water Science Center

USGS Publications Warehouse

Conn, Kathleen E.; Huffman, Raegan L.; Barton, Cynthia

2017-05-08

In accordance with guidelines set forth by the Office of Water Quality in the Water Mission Area of the U.S. Geological Survey, a quality-assurance plan has been created for use by the Washington Water Science Center (WAWSC) in conducting water-quality activities. This qualityassurance plan documents the standards, policies, and procedures used by the WAWSC for activities related to the collection, processing, storage, analysis, and publication of water-quality data. The policies and procedures documented in this quality-assurance plan for water-quality activities complement the quality-assurance plans for surface-water and groundwater activities at the WAWSC.

Determination of the origin of elevated uranium at a Former Air Force Landfill using non-parametric statistics analysis and uranium isotope ratio analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weismann, J.; Young, C.; Masciulli, S.

2007-07-01

Lowry Air Force Base (Lowry) was closed in September 1994 as part of the Base Realignment and Closure (BRAC) program and the base was transferred to the Lowry Redevelopment Authority in 1995. As part of the due diligence activities conducted by the Air Force, a series of remedial investigations were conducted across the base. A closed waste landfill, designated Operable Unit 2 (OU 2), was initially assessed in a 1990 Remedial Investigation (RI; [1]). A Supplemental Remedial Investigation was conducted in 1995 [2] and additional studies were conducted in a 1998 Focused Feasibility Study. [3] The three studies indicated thatmore » gross alpha, gross beta, and uranium concentrations were consistently above regulatory standards and that there were detections of low concentrations other radionuclides. Results from previous investigations at OU 2 have shown elevated gross alpha, gross beta, and uranium concentrations in groundwater, surface water, and sediments. The US Air Force has sought to understand the provenance of these radionuclides in order to determine if they could be due to leachates from buried radioactive materials within the landfill or whether they are naturally-occurring. The Air Force and regulators agreed to use a one-year monitoring and sampling program to seek to explain the origins of the radionuclides. Over the course of the one-year program, dissolved uranium levels greater than the 30 {mu}g/L Maximum Contaminant Level (MCL) were consistently found in both up-gradient and down-gradient wells at OU 2. Elevated Gross Alpha and Gross Beta measurements that were observed during prior investigations and confirmed during the LTM were found to correlate with high dissolved uranium content in groundwater. If Gross Alpha values are corrected to exclude uranium and radon contributions in accordance with US EPA guidance, then the 15 pCi/L gross alpha level is not exceeded. The large dataset also allowed development of gross alpha to total uranium correlation factors so that gross alpha action levels can be applied to future long-term landfill monitoring to track radiological conditions at lower cost. Ratios of isotopic uranium results were calculated to test whether the elevated uranium displayed signatures indicative of military use. Results of all ratio testing strongly supports the conclusion that the uranium found in groundwater, surface water, and sediment at OU 2 is naturally-occurring and has not undergone anthropogenic enrichment or processing. U-234:U-238 ratios also show that a disequilibrium state, i.e., ratio greater than 1, exists throughout OU 2 which is indicative of long-term aqueous transport in aged aquifers. These results all support the conclusion that the elevated uranium observed at OU 2 is due to the high concentrations in the regional watershed. Based on the results of this monitoring program, we concluded that the elevated uranium concentrations measured in OU 2 groundwater, surface water, and sediment are due to the naturally-occurring uranium content of the regional watershed and are not the result of waste burials in the former landfill. Several lines of evidence indicate that natural uranium has been naturally concentrated beneath OU 2 in the geologic past and the higher of uranium concentrations in down-gradient wells is the result of geochemical processes and not the result of a uranium ore disposal. These results therefore provide the data necessary to support radiological closure of OU 2. (authors)« less

Tracking natural and anthropogenic origins of dissolved arsenic during surface and groundwater interaction in a post-closure mining context: Isotopic constraints.

PubMed

Khaska, Mahmoud; Le Gal La Salle, Corinne; Verdoux, Patrick; Boutin, René

2015-01-01

Arsenic contamination of stream waters and groundwater is a real issue in Au-As mine environments. At the Salsigne Au-As mine, southern France, arsenic contamination persists after closure and remediation of the site. In this study, natural and anthropogenic arsenic inputs in surface water and groundwater are identified based on (87)Sr/(86)Sr, and δ(18)O and δ(2)H isotopic composition of water. In the wet season, downstream of the remediated zone, the arsenic contents in stream water and alluvial aquifer groundwater are high, with values in the order of 36 μg/L and 40 μg/L respectively, while upstream natural background average concentrations are around 4 μg/L. Locally down-gradient of the reclaimed area, arsenic concentrations in stream water showed 2 peaks, one during an important rainy event (101 mm) in the wet season in May, and a longer one over the dry period, reaching 120 and 110 μg/L respectively. The temporal variations in arsenic content in stream water can be explained i) during the dry season, by release of arsenic stored in the alluvial sediments through increased contribution from base flow and decreased stream flow and ii) during major rainy events, by mobilization of arsenic associated with important surface runoff. The (87)Sr/(86)Sr ratios associated with increasing arsenic content in stream waters downstream of the reclaimed area are significantly lower than that of the natural Sr inherited from Variscan formations. These low (87)Sr/(86)Sr ratios are likely to be associated with the decontaminating water treatment processes, used in the past and still at present, where CaO, produced from marine limestone and therefore showing a low (87)Sr/(86)Sr ratios, is used to precipitate Ca3(AsO4)2. The low Sr isotope signatures will then impact on the Sr isotope ratio of (1) the Ca-arsenate stored in tailing dams, (2) effluent currently produced by water treatment process and (3) groundwater draining from the overall site. Furthermore, Δ(2)H shows that the low (87)Sr/(86)Sr ratio, arsenic rich water is characterized by an evaporated signature suggesting a potential influence of water impacted by evaporation during storage in decantation lagoons. This study shows the suitability of Sr and stable isotopes of water as tracers to differentiate natural and anthropogenic sources of arsenic release or other trace elements from mining context where CaO is used for water treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Tracking natural and anthropogenic origins of dissolved arsenic during surface and groundwater interaction in a post-closure mining context: Isotopic constraints

NASA Astrophysics Data System (ADS)

Khaska, Mahmoud; Le Gal La Salle, Corinne; Verdoux, Patrick; Boutin, René

2015-06-01

Arsenic contamination of stream waters and groundwater is a real issue in Au-As mine environments. At the Salsigne Au-As mine, southern France, arsenic contamination persists after closure and remediation of the site. In this study, natural and anthropogenic arsenic inputs in surface water and groundwater are identified based on 87Sr/86Sr, and δ18O and δ2H isotopic composition of water. In the wet season, downstream of the remediated zone, the arsenic contents in stream water and alluvial aquifer groundwater are high, with values in the order of 36 μg/L and 40 μg/L respectively, while upstream natural background average concentrations are around 4 μg/L. Locally down-gradient of the reclaimed area, arsenic concentrations in stream water showed 2 peaks, one during an important rainy event (101 mm) in the wet season in May, and a longer one over the dry period, reaching 120 and 110 μg/L respectively. The temporal variations in arsenic content in stream water can be explained i) during the dry season, by release of arsenic stored in the alluvial sediments through increased contribution from base flow and decreased stream flow and ii) during major rainy events, by mobilization of arsenic associated with important surface runoff. The 87Sr/86Sr ratios associated with increasing arsenic content in stream waters downstream of the reclaimed area are significantly lower than that of the natural Sr inherited from Variscan formations. These low 87Sr/86Sr ratios are likely to be associated with the decontaminating water treatment processes, used in the past and still at present, where CaO, produced from marine limestone and therefore showing a low 87Sr/86Sr ratios, is used to precipitate Ca3(AsO4)2. The low Sr isotope signatures will then impact on the Sr isotope ratio of (1) the Ca-arsenate stored in tailing dams, (2) effluent currently produced by water treatment process and (3) groundwater draining from the overall site. Furthermore, Δ2H shows that the low 87Sr/86Sr ratio, arsenic rich water is characterized by an evaporated signature suggesting a potential influence of water impacted by evaporation during storage in decantation lagoons. This study shows the suitability of Sr and stable isotopes of water as tracers to differentiate natural and anthropogenic sources of arsenic release or other trace elements from mining context where CaO is used for water treatment.

Recharge processes in an alluvial aquifer riparian zone, Norman Landfill, Norman, Oklahoma, 1998-2000

USGS Publications Warehouse

Scholl, Martha; Christenson, Scott; Cozzarelli, Isabelle; Ferree, Dale; Jaeshke, Jeanne

2005-01-01

Analyses of stable isotope profiles (d2H and d18O) in the saturated zone, combined with water-table fluctuations, gave a comprehensive picture of recharge processes in an alluvial aquifer riparian zone. At the Norman Landfill U.S. Geological Survey Toxic Substances Hydrology research site in Norman, Oklahoma, recharge to the aquifer appears to drive biodegradation, contributing fresh supplies of electron acceptors for the attenuation of leachate compounds from the landfill. Quantifying recharge is a first step in studying this process in detail. Both chemical and physical methods were used to estimate recharge. Chemical methods included measuring the increase in recharge water in the saturated zone, as defined by isotopic signature, specific conductance or chloride measurements; and infiltration rate estimates using storm event isotopic signatures. Physical methods included measurement of water-table rise after individual rain events and on an approximately monthly time scale. Evapotranspiration rates were estimated using diurnal watertable fluctuations; outflux of water from the alluvial aquifer during the growing season had a large effect on net recharge at the site. Evaporation and methanogenesis gave unique isotopic signatures to different sources of water at the site, allowing the distinction of recharge using the offset of the isotopic signature from the local meteoric water line. The downward movement of water from large, isotopically depleted rain events in the saturated zone yielded recharge rate estimates (2.2 - 3.3 mm/day), and rates also were determined by observing changes in thickness of the layer of infiltrated recharge water at the top of the saturated zone (1.5 - 1.6 mm/day). Recharge measured over 2 years (1998-2000) in two locations at the site averaged 37 percent of rainfall, however, part of this water had only a short residence time in the aquifer. Isotopes showed recharge water entering the ground-water system in winter and spring, then being removed during the growing season by phreatophyte transpiration. Recharge timing was variable over the course of the study; July and August were the only months that had no recharge in both years. Recharge to the aquifer from the slough (wetland pond) was estimated at one location using the isotopic signature of water affected by evaporation. Recharge was correlated with the rainfall amount over the period of estimation, suggesting that recharge from the slough to the downgradient aquifer was an episodic process, corresponding to elevated water levels in the slough after large rain events.

Research on the Relationship between Water Diversion and Water Quality of Xuanwu Lake, China.

PubMed

Song, Weiwei; Xu, Qing; Fu, Xingqian; Zhang, Peng; Pang, Yong; Song, Dahao

2018-06-14

Water diversion is often used to improve water quality to reach the standard of China in the short term. However, this large amount of water diversion can not only improve the water quality, but also lead to a decline in the water quality (total phosphorus, total nitrogen) of Xuanwu Lake. Through theoretical analysis, the relationship between water quality and water diversion is established. We also found that the multiplication of the pollutant degradation coefficient ( K ) and the water residence time ( T ) is a constant ( N ), K⋅T=N. The water quality changed better at first, with the increase of inflow discharge, and then became worse, and the optimal water quality inflow discharge is 180,000 m³/day. By constructing two-dimensional hydrodynamic and water quality models, the optimal diversion water plan is calculated. Through model calculations, it can be seen that reducing the inflow discharge makes the water residence time longer (15.3 days changed to 23.8 days). Thereby, increasing the degradation of pollutants, and thus improving water quality. Compared with other wind directions, the southwest wind makes the water quality of Xuanwu Lake the most uniform. The concentration of water quality first became smaller and then became larger, as the wind speed increased, and eventually became constant. Implementing these results for water quality improvement in small and medium lakes will significantly reduce the cost of water diversion.

Spatio-Temporal Trends and Identification of Correlated Variables with Water Quality for Drinking-Water Reservoirs

PubMed Central

Gu, Qing; Wang, Ke; Li, Jiadan; Ma, Ligang; Deng, Jinsong; Zheng, Kefeng; Zhang, Xiaobin; Sheng, Li

2015-01-01

It is widely accepted that characterizing the spatio-temporal trends of water quality parameters and identifying correlated variables with water quality are indispensable for the management and protection of water resources. In this study, cluster analysis was used to classify 56 typical drinking water reservoirs in Zhejiang Province into three groups representing different water quality levels, using data of four water quality parameters for the period 2006–2010. Then, the spatio-temporal trends in water quality were analyzed, assisted by geographic information systems (GIS) technology and statistical analysis. The results indicated that the water quality showed a trend of degradation from southwest to northeast, and the overall water quality level was exacerbated during the study period. Correlation analysis was used to evaluate the relationships between water quality parameters and ten independent variables grouped into four categories (land use, socio-economic factors, geographical features, and reservoir attributes). According to the correlation coefficients, land use and socio-economic indicators were identified as the most significant factors related to reservoir water quality. The results offer insights into the spatio-temporal variations of water quality parameters and factors impacting the water quality of drinking water reservoirs in Zhejiang Province, and they could assist managers in making effective strategies to better protect water resources. PMID:26492263

Spatio-Temporal Trends and Identification of Correlated Variables with Water Quality for Drinking-Water Reservoirs.

PubMed

Gu, Qing; Wang, Ke; Li, Jiadan; Ma, Ligang; Deng, Jinsong; Zheng, Kefeng; Zhang, Xiaobin; Sheng, Li

2015-10-20

It is widely accepted that characterizing the spatio-temporal trends of water quality parameters and identifying correlated variables with water quality are indispensable for the management and protection of water resources. In this study, cluster analysis was used to classify 56 typical drinking water reservoirs in Zhejiang Province into three groups representing different water quality levels, using data of four water quality parameters for the period 2006-2010. Then, the spatio-temporal trends in water quality were analyzed, assisted by geographic information systems (GIS) technology and statistical analysis. The results indicated that the water quality showed a trend of degradation from southwest to northeast, and the overall water quality level was exacerbated during the study period. Correlation analysis was used to evaluate the relationships between water quality parameters and ten independent variables grouped into four categories (land use, socio-economic factors, geographical features, and reservoir attributes). According to the correlation coefficients, land use and socio-economic indicators were identified as the most significant factors related to reservoir water quality. The results offer insights into the spatio-temporal variations of water quality parameters and factors impacting the water quality of drinking water reservoirs in Zhejiang Province, and they could assist managers in making effective strategies to better protect water resources.

Monitoring and Assessment of Youshui River Water Quality in Youyang

NASA Astrophysics Data System (ADS)

Wang, Xue-qin; Wen, Juan; Chen, Ping-hua; Liu, Na-na

2018-02-01

By monitoring the water quality of Youshui River from January 2016 to December 2016, according to the indicator grading and the assessment standard of water quality, the formulas for 3 types water quality indexes are established. These 3 types water quality indexes, the single indicator index Ai, single moment index Ak and the comprehensive water quality index A, were used to quantitatively evaluate the quality of single indicator, the water quality and the change of water quality with time. The results show that, both total phosphorus and fecal coliform indicators exceeded the standard, while the other 16 indicators measured up to the standard. The water quality index of Youshui River is 0.93 and the grade of water quality comprehensive assessment is level 2, which indicated that the water quality of Youshui River is good, and there is room for further improvement. To this end, several protection measures for Youshui River environmental management and pollution treatment are proposed.

Water quality assessment of Australian ports using water quality evaluation indices

PubMed Central

Jahan, Sayka

2017-01-01

Australian ports serve diverse and extensive activities, such as shipping, tourism and fisheries, which may all impact the quality of port water. In this work water quality monitoring at different ports using a range of water quality evaluation indices was applied to assess the port water quality. Seawater samples at 30 stations in the year 2016–2017 from six ports in NSW, Australia, namely Port Jackson, Botany, Kembla, Newcastle, Yamba and Eden, were investigated to determine the physicochemical and biological variables that affect the port water quality. The large datasets obtained were designed to determine the Water Quality Index, Heavy metal Evaluation Index, Contamination Index and newly developed Environmental Water Quality Index. The study revealed medium water quality index and high and medium heavy metal evaluation index at three of the study ports and high contamination index in almost all study ports. Low level dissolved oxygen and higher level of total dissolved solids, turbidity, fecal coliforms, copper, iron, lead, zinc, manganese, cadmium and cobalt are mainly responsible for the poor water qualities of the port areas. Good water quality at the background samples indicated that various port activities are the likely cause for poor water quality inside the port area. PMID:29244876

Application of Nemerow Index Method and Integrated Water Quality Index Method in Water Quality Assessment of Zhangze Reservoir

NASA Astrophysics Data System (ADS)

Zhang, Qian; Feng, Minquan; Hao, Xiaoyan

2018-03-01

[Objective] Based on the water quality historical data from the Zhangze Reservoir from the last five years, the water quality was assessed by the integrated water quality identification index method and the Nemerow pollution index method. The results of different evaluation methods were analyzed and compared and the characteristics of each method were identified.[Methods] The suitability of the water quality assessment methods were compared and analyzed, based on these results.[Results] the water quality tended to decrease over time with 2016 being the year with the worst water quality. The sections with the worst water quality were the southern and northern sections.[Conclusion] The results produced by the traditional Nemerow index method fluctuated greatly in each section of water quality monitoring and therefore could not effectively reveal the trend of water quality at each section. The combination of qualitative and quantitative measures of the comprehensive pollution index identification method meant it could evaluate the degree of water pollution as well as determine that the river water was black and odorous. However, the evaluation results showed that the water pollution was relatively low.The results from the improved Nemerow index evaluation were better as the single indicators and evaluation results are in strong agreement; therefore the method is able to objectively reflect the water quality of each water quality monitoring section and is more suitable for the water quality evaluation of the reservoir.

The psychology of drinking water quality: An exploratory study

NASA Astrophysics Data System (ADS)

Syme, Geoffrey J.; Williams, Katrina D.

1993-12-01

Perceptions of drinking water quality were measured for residents at four locations in Western Australia. The total dissolved solid levels for the locations varied. Four scales of drinking water satisfaction were measured: acceptability of water quality; water quality risk judgment; perception of neighborhood water quality; and attitudes toward fluoride as an additive. Responses to each of these scales did not appear to be highly related to total dissolved solids. The relationship between attitudes toward water quality and a variety of psychological, attitudinal, experiential, and demographic variables was investigated. It was found that responses to the acceptability of water quality and water quality risk judgment scales related to perceived credibility of societal institutions and feelings of control over water quality and environmental problems. For the remaining two scales few significant correlations were found. The results support those who advocate localized information and involvement campaigns on drinking water quality issues.

40 CFR 130.3 - Water quality standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... QUALITY PLANNING AND MANAGEMENT § 130.3 Water quality standards. A water quality standard (WQS) defines the water quality goals of a water body, or portion thereof, by designating the use or uses to be made... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Water quality standards. 130.3 Section...

Contamination movement around a permeable reactive barrier at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina, 2009

USGS Publications Warehouse

Vroblesky, Don A.; Petkewich, Matthew D.; Conlon, Kevin J.

2010-01-01

The ability to monitor the fate and behavior of the plume in the forest is severely limited because the present axis of maximum contamination in that area bypasses all but one of the existing monitoring wells (12MW-12S). Moreover, the 2009 data indicate that there are no optimally placed sentinel wells in the probable path of contaminant transport. Thus the monitoring network is no longer adequate to monitor the groundwater contamination downgradient from the PRB.

The Impact of DNAPL Source-Zone Architecture on Contaminant Mass Flux and Plume Evolution in Heterogeneous Porous Media

DTIC Science & Technology

2013-08-01

remediation, ISCO, permanganate , persistence, DNAPL 16. SECURITY CLASSIFICATION OF: U 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF...focus on the lower-K zone 2 and surrounding higher-K matrix sand during the constant permanganate injection………………………… 45 Figure 5.1.3-3...Photographic image of the lower-K zone 2 and surrounding area after permanganate injection, exhibiting the shadow zone downgradient of the lower-K zone

Association between perceptions of public drinking water quality and actual drinking water quality: A community-based exploratory study in Newfoundland (Canada).

PubMed

Ochoo, Benjamin; Valcour, James; Sarkar, Atanu

2017-11-01

Studying public perception on drinking water quality is crucial for managing of water resources, generation of water quality standards, and surveillance of the drinking-water quality. However, in policy discourse, the reliability of public perception concerning drinking water quality and associated health risks is questionable. Does the public perception of water quality equate with the actual water quality? We investigated public perceptions of water quality and the perceived health risks and associated with the actual quality of public water supplies in the same communities. The study was conducted in 45 communities of Newfoundland (Canada) in 2012. First, a telephone survey of 100 households was conducted to examine public perceptions of drinking water quality of their respective public sources. Then we extracted public water quality reports of the same communities (1988-2011) from the provincial government's water resources portal. These reports contained the analysis of 2091 water samples, including levels of Disinfection By-Products (DBPs), nutrients, metals, ions and physical parameters. The reports showed that colour, manganese, total dissolved solids, iron, turbidity, and DBPs were the major detected parameters in the public water. However, the majority of the respondents (>56%) were either completely satisfied or very satisfied with the quality of drinking water. Older, higher educated and high-income group respondents were more satisfied with water quality than the younger, less educated and low-income group respondents. The study showed that there was no association with public satisfaction level and actual water quality of the respective communities. Even, in the communities, supplied by the same water system, the respondents had differences in opinion. Despite the effort by the provincial government to make the water-test results available on its website for years, the study showed existing disconnectedness between public perception of drinking water quality and actual quality. We had little scope to explore the possible explanations, and hence further studies are required to verify the age, gender educational status and income differential about the satisfaction of public service like water supply. Copyright © 2017 Elsevier Inc. All rights reserved.

40 CFR 131.35 - Colville Confederated Tribes Indian Reservation.

Code of Federal Regulations, 2013 CFR

2013-07-01

... PROGRAMS WATER QUALITY STANDARDS Federally Promulgated Water Quality Standards § 131.35 Colville Confederated Tribes Indian Reservation. The water quality standards applicable to the waters within the... these Federal water quality standards to prescribe minimum water quality requirements for the surface...

Hydrological and biogeochemical investigation of an agricultural watershed, southeast New Hampshire, USA

NASA Astrophysics Data System (ADS)

Davis, J. M.; McDowell, W. H.; Campbell, J. E.; Hristov, A. N.

2010-12-01

Developing sustainable agricultural practices and policies requires an understanding of the hydrological and biological processes that control nutrient fluxes and how those processes are manifested in nutrient loading of surface water bodies. Groundwater and surface water from the UNH Organic Research Dairy, located in southeast New Hampshire, flow into the Lamprey River and then into the Great Bay, New Hampshire; both are experiencing increasing nutrient loads. The farm hosts approximately 80 Jersey cows (40 milking) and is located on relatively thin (<10m) glacial deposits that include sandy glacial till moraines, an ice-contact delta, and marine silt and clay overlying fractured calcareous quartzite. Recharge of precipitation is the dominant mode through which nutrients are introduced into the hydrologic system. Intensive meteorological, hydrological, and biogeochemical monitoring of a 35 hectare watershed that includes the main farm operation buildings and several pastures has been underway since June 2009. A three-dimensional transient unsaturated-saturated groundwater flow model was developed using LIDAR topography and detailed field mapping. The transient model was calibrated to observed water level and streamflow observations. Model results suggest that summer recharge rates vary considerably across the site and depth to the water table is the dominant control on the recharge flux. Areas having depth to water of 1-2 m experience the greatest recharge (up to 60% of precipitation). Areas with deeper water tables experience greater evapotranspiration from the vadose zone, and shallower water tables experience greater runoff. Water budget calculations suggest that the hydrologic fluxes occur predominately in the shallow groundwater, wetlands, and small surface streams draining the watershed. High dissolved nitrogen (N) concentrations (up to an average concentration of 35 mg N/L) are observed in groundwater immediately downgradient from the main farm operation and decrease more than an order of magnitude along the flowpaths. However, Nitrogen-15 concentrations do not change appreciably along flowpaths, suggesting that reductions in N concentrations are primarily due to dilution rather than denitrification. Our overall objective is to understand how farm hydrology and biogeochemistry are linked to farm management. Our understanding of biophysical feedbacks and functional links can be used to guide sustainable management actions, informing decisions about the timing and location of manure applications and other farm operations.

[Study on the optimization of monitoring indicators of drinking water quality during health supervision].

PubMed

Ye, Bixiong; E, Xueli; Zhang, Lan

2015-01-01

To optimize non-regular drinking water quality indices (except Giardia and Cryptosporidium) of urban drinking water. Several methods including drinking water quality exceed the standard, the risk of exceeding standard, the frequency of detecting concentrations below the detection limit, water quality comprehensive index evaluation method, and attribute reduction algorithm of rough set theory were applied, redundancy factor of water quality indicators were eliminated, control factors that play a leading role in drinking water safety were found. Optimization results showed in 62 unconventional water quality monitoring indicators of urban drinking water, 42 water quality indicators could be optimized reduction by comprehensively evaluation combined with attribute reduction of rough set. Optimization of the water quality monitoring indicators and reduction of monitoring indicators and monitoring frequency could ensure the safety of drinking water quality while lowering monitoring costs and reducing monitoring pressure of the sanitation supervision departments.

Chromium Isotopic Monitoring of HRC-Stimulated Bio-containment at the 100H Test Site, Hanford, Washington

NASA Astrophysics Data System (ADS)

Christensen, J. N.; Brown, S. T.; Brodie, E. L.; Chakraborty, R.; Conrad, M. E.; Long, P. E.; Faybishenko, B.; Hazen, T. C.

2007-12-01

Hexavalent Cr (Cr(VI)) groundwater contamination is a common problem in the U.S. associated with industrial activity (e.g. electroplating, tanning, paints, anti-corrosion). In the particular case of the Hanford Site, Washington, chromate was used primarily to inhibit corrosion in nuclear reactor cooling systems. During the active operation of the Hanford Site, disposal of waste water bearing chromate, and accidental releases to the vadose zone resulted in significant groundwater contamination with local concentrations near the Columbia river reaching over 1000 ppb Cr(VI). In an effort to test an effective bio-containment strategy for groundwater Cr(VI), a site was selected between the 100D and 100H reactor areas with modest concentrations (~100 ppb Cr(VI) over the past two decades). A slow-release 13C labeled polylactate amendment (HRCTM, Regenesis, Ltd.) was injected into groundwater within a sandy formation to stimulate bacterial activity in order to produce conditions that promote the reduction of dissolved Cr(VI) to insoluble Cr(III) complexes [1]. Since the injection of HRCTM in August 2004, groundwater Cr(VI) concentration has been locally below 1 ppb, and reducing conditions have been maintained to at least the present time. The isotopic composition of Cr can be fractionated during reduction from Cr(VI) to Cr(III) and so has the potential to be used as a monitor of hexavalent Cr reduction [2, 3]. This would provide a direct signature of Cr(VI) reduction, discernable from simple attenuation by dilution. In order to explore the use of Cr isotopic measurements for evaluating processes of Cr(VI) reduction, we have analyzed a series of samples in space and time for Cr isotopic composition (δ53Cr, permil deviation of sample 53Cr/52Cr from that of SRM970). Groundwater samples came from the HRC injection well, from multiple depths of three down-gradient wells, and from an up-gradient well. Samples from down-gradient wells have Cr that is isotopically fractionated relative to samples from the up-gradient well. Taken together, samples from a single sampling campaign yield an apparent fractionation of 2.2 ‰. Cr isotopic measurements of the latest samples (June, 2007) confirm continued reduction of Cr(VI) nearly three years after the introduction of HRCTM, suggesting the long-term effectiveness of this bio-stimulated containment strategy. [1] http://esd.lbl.gov/ERT/hanford100h/ [2] Ellis, AS, Johnson, TM and Bohlen, TD (2002) Science. 295:2060-2062. [3] Johnson, TM and Bohlen, TD (2004) Reviews in Mineralogy and Geochemistry, Vol. 55, p.289-317.

40 CFR 130.3 - Water quality standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 23 2012-07-01 2012-07-01 false Water quality standards. 130.3 Section 130.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.3 Water quality standards. A water quality standard (WQS) defines...

40 CFR 130.3 - Water quality standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 22 2014-07-01 2013-07-01 true Water quality standards. 130.3 Section 130.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.3 Water quality standards. A water quality standard (WQS) defines...

40 CFR 130.3 - Water quality standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 23 2013-07-01 2013-07-01 false Water quality standards. 130.3 Section 130.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.3 Water quality standards. A water quality standard (WQS) defines...

40 CFR 130.3 - Water quality standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 22 2011-07-01 2011-07-01 false Water quality standards. 130.3 Section 130.3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.3 Water quality standards. A water quality standard (WQS) defines...

Water Quality of Hills Water, Supply Water and RO Water Machine at Ulu Yam Selangor

NASA Astrophysics Data System (ADS)

Ngadiman, N.; ‘I Bahari, N.; Kaamin, M.; Hamid, N. B.; Mokhtar, M.; Sahat, S.

2016-07-01

The rapid development resulted in the deterioration of the quality of drinking water in Malaysia. Recognizing the importance of water quality, new alternatives for drinking water such as mineral water processing from reverse osmosis (RO) machine become more popular. Hence, the demand for mineral water, natural spring water or water from the hills or mountains rose lately. More consumers believed the quality of these spring water better than other source of drinking water. However, the quality of all the drinking water sources is to meet the required quality standard. Therefore, this paper aims to measure the quality of the waters from hills, from RO machine and the water supply in Ulu Yam, Selangor Batang Kali, Malaysia. The water quality was determined based on following parameters: ammoniacal nitrogen (NH3), iron (Fe), turbidity (NTU) and pH. The results show that the water from hills has better quality compared to water supply and water from RO machine. The value of NH3 ranged from 0.03 mg/L- 0.67 mg/L; Fe was from 0.03mg/L - 0.12 mg/L, turbidity at 0.42 NTU - 0.88 NTU and pH is at 6.60 - 0.71. Based on the studied parameters, all three types of water are fit for drinking and have met the required national drinking water quality standard.

Evaluating benefits and costs of changes in water quality.

Treesearch

Jessica Koteen; Susan J. Alexander; John B. Loomis

2002-01-01

Water quality affects a variety of uses, such as municipal water consumption and recreation. Changes in water quality can influence the benefits water users receive. The problem is how to define water quality for specific uses. It is not possible to come up with one formal definition of water quality that fits all water uses. There are many parameters that influence...

18 CFR 801.7 - Water quality.

Code of Federal Regulations, 2010 CFR

2010-04-01

... water quality management and control. However, protection of the water resources of the basin from... quality program in the comprehensive plan. (c) The Commission's role in water quality management and... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Water quality. 801.7...

40 CFR 130.6 - Water quality management plans.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 23 2012-07-01 2012-07-01 false Water quality management plans. 130.6 Section 130.6 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.6 Water quality management plans. (a) Water quality management (WQM...

40 CFR 130.6 - Water quality management plans.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 23 2013-07-01 2013-07-01 false Water quality management plans. 130.6 Section 130.6 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.6 Water quality management plans. (a) Water quality management (WQM...

40 CFR 130.6 - Water quality management plans.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 22 2014-07-01 2013-07-01 true Water quality management plans. 130.6 Section 130.6 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.6 Water quality management plans. (a) Water quality management (WQM...

40 CFR 130.6 - Water quality management plans.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Water quality management plans. 130.6... QUALITY PLANNING AND MANAGEMENT § 130.6 Water quality management plans. (a) Water quality management (WQM... and certified and approved updates to those plans. Continuing water quality planning shall be based...