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.

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.

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

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.

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

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

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

Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers in a Sand and Gravel Aquifer, Cape Cod, Massachusetts, 1997-2000

USGS Publications Warehouse

Savoie, Jennifer G.; Kent, Douglas B.; Smith, Richard L.; LeBlanc, Denis R.; Hubble, David W.

2004-01-01

Two experimental permeable reactive barriers (PRBs) of granular zero-valent iron were emplaced in the path of a tetrachloroethene plume (the Chemical Spill-10 plume) at the Massachusetts Military Reservation, Cape Cod, Massachusetts, in June 1998. The goal of the field experiment was to achieve emplacement of a granular-iron PRB deeper than attempted before. The PRBs were expected to create a reducing environment and degrade the tetrachloroethene by reductive dechlorination. The goal of the work presented in this report was to observe temporary and sustained changes to the ground-water chemistry downgradient from the PRBs. A hydraulic-fracturing method involving injection of the granular iron with a guar-biopolymer and enzyme slurry was used to install the parallel 30- to 33-foot-wide wall-shaped barriers at a depth of 82 to 113 feet below land surface. An acetic acid and enzyme mixture was subsequently injected in wells near the barriers to degrade the guar biopolymer. Prior to the emplacement, tetrachloroethene concentrations in the Chemical Spill-10 plume at the study area were as high as 250 micrograms per liter. Other water properties in the plume generally were similar to the properties of uncontaminated ground water in the area, which typically has dissolved oxygen concentrations of 250 to 375 micromoles per liter, pH of 5.5 to 6.0, and specific conductance of 60 to 90 microsiemens per centimeter. Water-quality samples were collected periodically from monitoring wells near the PRBs to determine how the emplacement of the granular-iron walls altered the ground-water quality. In addition, an automated well-sampling device measured temperature, specific conductance, pH, and dissolved oxygen every 1?4 days for 16 months in a well downgradient from the two parallel PRBs. Temporary increases (lasting about 5 to 6 months) in specific conductance were observed downgradient from the PRBs as a result of the sodium chloride, potassium carbonate, and other salts included in the slurry and the acetic acid and enzyme mixture that was subsequently injected to degrade the guar biopolymer. Temporary increases in the concentrations of major cations (sodium, potassium, magnesium, and calcium) were observed downgradient from the PRBs, as were temporary but substantial increases in the dissolved and total organic carbon concentrations. Methane was detected, sulfate concentrations decreased temporarily, and concentrations of dissolved inorganic carbon increased in samples from wells downgradient from the PRBs. A sustained (longer than 12 months) reducing environment, in which dissolved oxygen concentrations decreased to zero, the pH increased to about 6.8, and dissolved iron concentrations increased substantially, developed as a result of the oxidation (corrosion) of the granular iron; this zone persisted at least 65 feet downgradient from the PRBs. The pH and dissolved iron concentrations increased with distance from the granular-iron walls. Concentrations of arsenic, cobalt, manganese, and phosphorus increased, and nitrate concentrations were reduced to below the detection limit downgradient from the walls. A sustained decrease of tetrachloroethene concentrations was not observed; however, reductive dechlorination products were observed at wells downgradient from the PRBs during several rounds of sampling. The emplacement of zero-valent iron in the aquifer to remove tetrachloroethene from the ground water caused changes in the water chemistry that persisted farther downgradient from the PRBs than has been observed at other sites because of the low chemical reactivity of the quartz-dominated aquifer sediments and the low ambient dissolved chemical concentrations in the ground water. The small transverse dispersion in the aquifer and the probable long-term persistence of the iron indicate that the chemically altered zone probably will extend a substantial distance downgradient from the PRBs for a substantial period of time (years); fur

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

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

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.

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.

Hydrologic environments and water-quality characteristics at four landfills in Mecklenburg County, North Carolina, 1980-86

USGS Publications Warehouse

Cardinell, A.P.; Barnes, C.R.; Eddins, W.H.; Coble, R.W.

1989-01-01

A water-quality study was conducted during 1980-86 at four landfills in Mecklenburg County, North Carolina. Each landfill has a three-layered hydrogeologic system typical of the Piedmont, consisting of (1) the regolith; (2) a transition zone; and (3) unweathered, fractured crystalline bedrock. As much as 7.6 inches per year of rainfall enters the ground-water system and has the potential to generate leachate within landfill cells. Ground water and leachate discharge to tributaries within the landfill sites or to streams adjacent to them. Water-quality samples were collected from 53 monitoring wells and 20 surface-water sites. Samples were analyzed for selected physical and biological characteristics, major inorganic ions, nutrients, trace elements, and organic compounds. Selected indicators of water quality, including specific conductance; hardness; and concentrations of chloride, manganese, dissolved solids, total organic carbon, and specific organic compounds were analyzed to determine the effects of each landfill on ground- and surface-water quality. Increases in concentrations of inorganic constituents above background levels were detected in ground water downgradient of the landfills. The increases were generally greatest in samples from wells in close proximity to the older landfill cells. In general, the increases in concentrations in downgradient wells were greater for calcium, magnesium, and chloride than for other major ions. Manganese exhibited the largest relative increase in concentration between upgradient and downgradient wells of any constituent, and manganese concentration data were effective in defining areas with extensive anaerobic biological activity. Differences between upgradient and downgradient concentrations of total organic carbon and specific organic compounds generally were not as apparent. The most frequently identified organic contaminants were the herbicides 2,4-D and 2,4,5-T. Chlorofluoromethanes were identified in three of four ground-water samples analyzed for volatile organic compounds. Landfills affected the water quality of several smaller streams but did not noticeably affect larger ones. Apparent effects on water quality were greatest at the oldest landfill, located on Statesville Road, where waste is in cells that are partly below the water table.

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

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

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.

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.

Ground-water quality, levels, and flow direction near Fort Cobb Reservoir, Caddo County, Oklahoma, 1998-2000

USGS Publications Warehouse

Becker, Carol J.

2001-01-01

Fort Cobb Reservoir in northwest Caddo County Oklahoma is managed by the Bureau of Reclamation for water supply, recreation, flood control, and wildlife. Excessive amounts of nitrogen in the watershed have the potential to cause long-term eutrophication of the reservoir and increase already elevated concentrations of nitrogen in the Rush Springs aquifer. The U.S. Geological Survey in cooperation with the Bureau of Reclamation studied ground water in the area surrounding a swine feeding operation located less than 2 miles upgradient from Fort Cobb Reservoir in Caddo County, Oklahoma. Objectives of the study were to (1) determine if the operation was contributing nitrogen to the ground water and (2) measure changes in ground-water levels and determine the local ground-water flow direction in the area surrounding the swine feeding operation. Nitrate concentrations (28.1 and 31.5 milligrams per liter) were largest in two ground-water samples from a well upgradient of the wastewater lagoon. Nitrate concentrations ranged from 4.30 to 8.20 milligrams per liter in samples from downgradient wells. Traces of ammonia and nitrite were detected in a downgradient well, but not in upgradient wells. d15N values indicate atmospheric nitrogen, synthetic fertilizer, or plants were the predominate sources of nitrate in ground water from the downgradient wells. The d15N values in these samples are depleted in nitrogen-15, indicating that animal waste was not a significant contributor of nitrate. Manganese concentrations (1,150 and 965 micrograms per liter) in samples from a downgradient well were substantially larger than concentrations in samples from other wells, exceeding the secondary drinking-water standard of 50 micrograms per liter. Larger concentrations of bicarbonate, magnesium, fluoride, and iron and a higher pH were also measured in water from a downgradient well. Ground-water levels in an observation well were higher from April to mid-July and lower during the late summer and in the fall due to a seasonal decrease in precipitation, increase in water withdrawals, and increase in evapotranspiration. Ground water near the wastewater spray field moved south-southeast toward Willow Creek along a gradient of about 50 feet per mile. Analysis of ground-water samples suggest that commercial fertilizer is contributing nitrate upgradient of the swine feeding operation and that wastewater from the lagoon is contributing reduced forms of nitrogen, ammonia and nitrite. Additional downgradient wells would be needed to (1) determine if the swine feeding operation is adding excessive amounts of nitrogen to ground water, (2) determine the vertical dimension of wastewater flow, and (3) the extent of wastewater downgradient of the lagoon.

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

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

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.

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)

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

Ground-water levels, flow, and quality in northwestern Elkhart County, Indiana, 1980-89

USGS Publications Warehouse

Duwelius, R.F.; Silcox, C.A.

1991-01-01

The time of peak dissolved-bromide concentrations in water from shallow wells downgradient from the landfill was used to estimate a rate of horizontal flow of water in the unconfined aquifer. The average rate of flow between shallow wells downgradient from the landfill was estimated to be 1.2 feet per day. This rate is within the range of values for ground-water flow calculated according to Darcy's law.

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

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.

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)

Time-lapse 3-D electrical resistance tomography inversion for crosswell monitoring of dissolved and supercritical CO 2 flow at two field sites: Escatawpa and Cranfield, Mississippi, USA

DOE PAGES

Commer, Michael; Doetsch, Joseph; Dafflon, Baptiste; ...

2016-06-01

In this study, we advance the understanding of three-dimensional (3-D) electrical resistivity tomography (ERT) for monitoring long-term CO 2 storage by analyzing two previously published field time-lapse data sets. We address two important aspects of ERT inversion-the issue of resolution decay, a general impediment to the ERT method, and the issue of potentially misleading imaging artifacts due to 2-D model assumptions. The first study analyzes data from a shallow dissolved-CO 2 injection experiment near Escatawpa (Mississippi), where ERT data were collected in a 3-D crosswell configuration. Here, we apply a focusing approach designed for crosswell configurations to counteract resolution lossmore » in the inter-wellbore area, with synthetic studies demonstrating its effectiveness. The 3-D field data analysis reveals an initially southwards-trending flow path development and a dispersing plume development in the downgradient inter-well region. The second data set was collected during a deep (over 3 km) injection of supercritical CO 2 near Cranfield (Mississippi). Comparative 2-D and 3-D inversions reveal the projection of off-planar anomalies onto the cross-section, a typical artifact introduced by 2-D model assumptions. Conforming 3-D images from two different algorithms support earlier hydrological investigations, indicating a conduit system where flow velocity variations lead to a circumvention of a close observation well and an onset of increased CO 2 saturation downgradient from this well. We relate lateral permeability variations indicated by an independently obtained hydrological analysis to this consistently observed pattern in the CO 2 spatial plume evolution.« less

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.

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.

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

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

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.

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.

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.

Wilson Corners SWMU 001 2014 Annual Long Term Monitoring Report Kennedy Space Center, Florida

NASA Technical Reports Server (NTRS)

Langenbach, James

2015-01-01

This document presents the findings of the 2014 Long Term Monitoring (LTM) that was completed at the Wilson Corners site, located at the National Aeronautics and Space Administration (NASA) John F. Kennedy Space Center (KSC), Florida. The goals of the 2014 annual LTM event were to evaluate the groundwater flow direction and gradient and to monitor the vertical and downgradient horizontal extent of the volatile organic compounds (VOCs) in groundwater at the site. The LTM activities consisted of an annual groundwater sampling event in December 2014, which included the collection of water levels from the LTM wells. During the annual groundwater sampling event, depth to groundwater was measured and VOC samples were collected using passive diffusion bags (PDBs) from 30 monitoring wells. In addition to the LTM sampling, additional assessment sampling was performed at the site using low-flow techniques based on previous LTM results and assessment activities. Assessment of monitoring well MW0052DD was performed by collecting VOC samples using low-flow techniques before and after purging 100 gallons from the well. Monitoring well MW0064 was sampled to supplement shallow VOC data north of Hot Spot 2 and east of Hot Spot 4. Monitoring well MW0089 was sampled due to its proximity to MW0090. MW0090 is screened in a deeper interval and had an unexpected detection of trichloroethene (TCE) during the 2013 LTM, which was corroborated during the March 2014 verification sampling. Monitoring well MW0130 was sampled to provide additional VOC data beneath the semi-confining clay layer in the Hot Spot 2 area.

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-quality reconnaissance of the north Dade County solid-waste facility, Florida

USGS Publications Warehouse

McKenzie, D.J.

1982-01-01

A water-quality sampling reconnaissance of the north Dade County solid-waste disposal facility (landfill) near Carol City, Florida, was conducted during 1977-78. The purpose of the reconnaissance was to determine selected quality characteristics of the surface- and ground-water of the landfill and contiguous area; and to assess, generally, if leachate produced by the decomposition of landfill wastes was adversely impacting the downgradient water quality. Sampling results indicated that several water-quality characteristics were present in landfill ground water at significantly higher levels than in ground water upgradient or downgradient from the landfill. Moreover, many of these water-quality characteristics were found at slightly higher levels at down gradient site 5 than at upgradient site 1 which suggested that some downgradient movement of landfill leachate had occurred. For example, chloride and alkalinity in ground water had average concentrations of 20 and 290 mg/L at background wells (site 1), 144 and 610 mg/L at landfill wells (sites 2 and 4), and 29 and 338 mg/L at downgradient wells (site 5). A comparison of the 1977-78 sampling results with the National Primary and Secondary Drinking Water Regulations indicated that levels of iron and color in ground water of the study area frequently exceeded national maximum contaminant levels, dissolved solids, turbidity, lead, and manganese occasionally exceeded regulations. Concentrations of iron and levels of color and turbidity in some surface water samples also exceeded National maximum contaminant levels. (USGS)

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

40 CFR 265.91 - Ground-water monitoring system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... sufficient to yield ground-water samples that are: (i) Representative of background ground-water quality in... not required provided that provisions for sampling upgradient and downgradient water quality will... perforated, and packed with gravel or sand where necessary, to enable sample collection at depths where...

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.

Long-term performance monitoring for a permeable reactive barrier at the U.S. Coast Guard Support Center, Elizabeth City, North Carolina.

PubMed

Puls, R W; Blowes, D W; Gillham, R W

1999-08-12

A continuous hanging iron wall was installed in June, 1996, at the U. S. Coast Guard (USCG) Support Center near Elizabeth City, NC, United States, to treat overlapping plumes of chromate and chlorinated solvent compounds. The wall was emplaced using a continuous trenching machine whereby native soil and aquifer sediment was removed and the iron simultaneously emplaced in one continuous excavation and fill operation. To date, there have been seven rounds (November 1996, March 1997, June 1997, September 1997, December 1997, March 1998, and June 1998) of performance monitoring of the wall. At this time, this is the only full-scale continuous 'hanging' wall installed as a permeable reactive barrier to remediate both chlorinated solvent compounds and chromate in groundwater. Performance monitoring entails the following: sampling of 10-5 cm PVC compliance wells and 15 multi-level samplers for the following constituents: TCE, cis-dichloroethylene (c-DCE), vinyl chloride, ethane, ethene, acetylene, methane, major anions, metals, Cr(VI), Fe(II), total sulfides, dissolved H(2), Eh, pH, dissolved oxygen, specific conductance, alkalinity, and turbidity. Electrical conductivity profiles have been conducted using a Geoprobe to verify emplacement of the continuous wall as designed and to locate upgradient and downgradient wall interfaces for coring purposes. Coring has been conducted in November, 1996, in June and September, 1997, and March, 1998, to evaluate the rate of corrosion on the iron surfaces, precipitate buildup (particularly at the upgradient interface), and permeability changes due to wall emplacement. In addition to several continuous vertical cores, angled cores through the 0.6-m thick wall have been collected to capture upgradient and downgradient wall interfaces along approximate horizontal flow paths for mineralogic analyses.

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.

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.

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 .

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

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

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 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.

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.

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

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

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

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.

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

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)

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.

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.

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

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

Ground-water quality near the northwest 58th Street solid-waste disposal facility, Dade County, Florida

USGS Publications Warehouse

Mattraw, H.C.; Hull, John E.; Klein, Howard

1978-01-01

The Northwest 58th Street solid-waste disposal facility, 3 miles west of a major Dade County municipal water-supply well field, overlays the Biscayne aquifer, a permeable, solution-riddled limestone which transmits leachates eastward at a calculated rate of 2.9 feet per day. A discrete, identifiable leachate plume has been recognized under and downgradient from the waste disposal facility. Concentrations of sodium, ammonia, and dissolved solids decreased with depth beneath the disposal area and downgradient in response to an advective and convective dispersion. At a distance of about one-half downgradient, the rate of contribution of leachate from the source to the leading edge of the plume was about equal to the rate of loss of leachate from the leading edge of the plume by diffusion and dilution by rainfall infiltration during the period August 1973 - July 1975. Heavy metals and pesticides are filtered, adsorbed by aquifer materials, or are precipitated near the disposal area. (Woodard-USGS)

Steroid estrogens, nonylphenol ethoxylate metabolites, and other wastewater contaminants in groundwater affected by a residential septic system on Cape Cod, MA.

PubMed

Swartz, Christopher H; Reddy, Sharanya; Benotti, Mark J; Yin, Haifei; Barber, Larry B; Brownawell, Bruce J; Rudel, Ruthann A

2006-08-15

Septic systems serve approximately 25% of U.S. households and may be an important source of estrogenic and other organic wastewater contaminants (OWC) to groundwater. We monitored several estrogenic OWC, including nonylphenol (NP), nonylphenol mono- and diethoxycarboxylates (NP1EC and NP2EC), the steroid hormones 17beta-estradiol (E2), estrone (E1) and their glucuronide and sulfate conjugates, and other OWC such as methylene blue active substances (MBAS), caffeine and its degradation product paraxanthine, and two fluorescent whitening agents in a residential septic system and in downgradient groundwater. E1 and E2 were present predominantly as free estrogens in groundwater, and near-source groundwater concentrations of all OWC were highest in the suboxic to anoxic portion of the wastewater plume, where concentrations of most OWC were similar to those observed in the septic tank on the same day. NP and NP2EC were up to 6- to 30-fold higher, and caffeine and paraxanthine were each 60-fold lower than septic tank concentrations, suggesting net production and removal, respectively, of these constituents. At the most shallow, oxic depth, concentrations of all OWC except for NP2EC were substantially lower than in the tank and in deeper wells. Yet boron, specific conductance, and the sum of nitrate-and ammonia-nitrogen were highest at this shallow depth, suggesting preferential losses of OWC along the more oxic flow lines. As far as 6.0 m downgradient, concentrations of many OWC were within a factor of 2 of near-source concentrations. The results suggest that there is the potential for migration of these OWC, which are unregulated and not routinely monitored, in groundwater.

Steroid estrogens, nonylphenol ethoxylate metabolites, and other wastewater contaminants in groundwater affected by a residential septic system on cape cod, MA

USGS Publications Warehouse

Swartz, C.H.; Reddy, S.; Benotti, M.J.; Yin, H.; Barber, L.B.; Brownawell, Bruce J.; Rudel, R.A.

2006-01-01

Septic systems serve approximately 25% of U.S. households and may be an important source of estrogenic and other organic wastewater contaminants (OWC) to groundwater. We monitored several estrogenic OWC, including nonylphenol (NP), nonylphenol mono- and diethoxycarboxylates (NP1EC and NP2EC), the steroid hormones 17??-estradiol (E2), estrone (E1) and their glucuronide and sulfate conjugates, and other OWC such as methylene blue active substances (MBAS), caffeine and its degradation product paraxanthine, and two fluorescent whitening agents in a residential septic system and in downgradient groundwater. E1 and E2 were present predominantly as free estrogens in groundwater, and near-source groundwater concentrations of all OWC were highest in the suboxic to anoxic portion of the wastewater plume, where concentrations of most OWC were similar to those observed in the septic tank on the same day. NP and NP2EC were up to 6- to 30-fold higher, and caffeine and paraxanthine were each 60-fold lower than septic tank concentrations, suggesting net production and removal, respectively, of these constituents. At the most shallow, oxic depth, concentrations of all OWC except for NP2EC were substantially lower than in the tank and in deeper wells. Yet boron, specific conductance, and the sum of nitrate-and ammonia-nitrogen were highest at this shallow depth, suggesting preferential losses of OWC along the more oxic flow lines. As far as 6.0 m downgradient, concentrations of many OWC were within a factor of 2 of near-source concentrations. The results suggest that there is the potential for migration of these OWC, which are unregulated and not routinely monitored, in groundwater. ?? 2006 American Chemical Society.

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.

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.

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.

Ground-water quality in the Davie Landfill, Broward County, Florida

USGS Publications Warehouse

Mattraw, H.C.

1976-01-01

Ground-water adjacent to a disposal pond for septic tank sludge, oil, and grease at the Davie landfill, Broward County, Florida was tested for a variety of ground-water contaminants. Three wells adjacent to the disposal pond yielded water rich in nutrients, organic carbon and many other chemical constituents. Total coliform bacteria ranged from less than 100 to 660 colonies per 100 milliliters in samples collected from the shallowest well (depth 20 feet). At well depths of 35 and 45 feet bacterial counts were less than 20 colonies per 100 milliliters or zero. Concentrations of several constituents in water samples collected from the wells downgradient from the landfill, disposal pond, and an incinerator wash pond were greater than in samples collected from wells immediately upgradient of the landfill. A comparison of sodium-chloride ion ratios indicated that downgradient ground-water contamination was related to the incinerator wash water pond rather than the septic tank sludge pond. (Woodard-USGS)

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.

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.

Monitoring and source tracking of tetracycline resistance genes in lagoons and groundwater adjacent to swine production facilities over a 3-year period

USGS Publications Warehouse

Koike, S.; Krapac, I.G.; Oliver, H.D.; Yannarell, A.C.; Chee-Sanford, J. C.; Aminov, R.I.; Mackie, R.I.

2007-01-01

To monitor the dissemination of resistance genes into the environment, we determined the occurrence of tetracycline resistance (Tcr) genes in groundwater underlying two swine confinement operations. Monitoring well networks (16 wells at site A and 6 wells at site C) were established around the lagoons at each facility. Groundwater (n = 124) and lagoon (n = 12) samples were collected from the two sites at six sampling times from 2000 through 2003. Total DNA was extracted, and PCR was used to detect seven Tcr genes [tet(M), tet(O), tet(Q), tet(W), tet(C), tet(H), and tet(Z)]. The concentration of Tcr genes was quantified by real-time quantitative PCR. To confirm the Tcr gene source in groundwater, comparative analysis of tet(W) gene sequences was performed on groundwater and lagoon samples. All seven Tcr genes were continually detected in groundwater during the 3-year monitoring period at both sites. At site A, elevated detection frequency and concentration of Tcr genes were observed in the wells located down-gradient of the lagoon. Comparative analysis of tet(W) sequences revealed that the impacted groundwater contained gene sequences almost identical (99.8% identity) to those in the lagoon, but these genes were not found in background libraries. Novel sequence clusters and unique indigenous resistance gene pools were also found in the groundwater. Thus, antibiotic resistance genes in groundwater are affected by swine manure, but they are also part of the indigenous gene pool. Copyright ?? 2007, American Society for Microbiology. All Rights Reserved.

Monitoring and Source Tracking of Tetracycline Resistance Genes in Lagoons and Groundwater Adjacent to Swine Production Facilities over a 3-Year Period▿

PubMed Central

Koike, S.; Krapac, I. G.; Oliver, H. D.; Yannarell, A. C.; Chee-Sanford, J. C.; Aminov, R. I.; Mackie, R. I.

2007-01-01

To monitor the dissemination of resistance genes into the environment, we determined the occurrence of tetracycline resistance (Tcr) genes in groundwater underlying two swine confinement operations. Monitoring well networks (16 wells at site A and 6 wells at site C) were established around the lagoons at each facility. Groundwater (n = 124) and lagoon (n = 12) samples were collected from the two sites at six sampling times from 2000 through 2003. Total DNA was extracted, and PCR was used to detect seven Tcr genes [tet(M), tet(O), tet(Q), tet(W), tet(C), tet(H), and tet(Z)]. The concentration of Tcr genes was quantified by real-time quantitative PCR. To confirm the Tcr gene source in groundwater, comparative analysis of tet(W) gene sequences was performed on groundwater and lagoon samples. All seven Tcr genes were continually detected in groundwater during the 3-year monitoring period at both sites. At site A, elevated detection frequency and concentration of Tcr genes were observed in the wells located down-gradient of the lagoon. Comparative analysis of tet(W) sequences revealed that the impacted groundwater contained gene sequences almost identical (99.8% identity) to those in the lagoon, but these genes were not found in background libraries. Novel sequence clusters and unique indigenous resistance gene pools were also found in the groundwater. Thus, antibiotic resistance genes in groundwater are affected by swine manure, but they are also part of the indigenous gene pool. PMID:17545324

GeoChip-based Analysis of Groundwater Microbial Diversity in Norman Landfill

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

Lu, Zhenmei; He, Zhili; Parisi, Victoria

The Norman Landfill is a closed municipal solid waste landfill located on an alluvium associated with the Canadian River in Norman, Oklahoma. It has operated as a research site since 1994 because it is typical of many closed landfill sites across the U.S. Leachate from the unlined landfill forms a groundwater plume that extends downgradient approximately 250 m from the landfill toward the Canadian River. To investigate the impact of the landfill leachate on the diversity and functional structure of microbial communities, groundwater samples were taken from eight monitoring wells at a depth of 5m, and analyzed using a comprehensivemore » functional gene array covering about 50,000 genes involved in key microbial processes, such as biogeochemical cycling of C, N, P, and S, and bioremediation of organic contaminants and metals. Wells are located within a transect along a presumed flow path with different distances to the center of the leachate plume. Our analyses showed that microbial communities were obviously impacted by the leachate-component from the landfill. The number of genes detected and microbial diversity indices in the center (LF2B) and its closest (MLS35) wells were significantly less than those detected in other more downgradient wells, while no significant changes were observed in the relative abundance (i.e., percentage of each gene category) for most gene categories. However, the microbial community composition or structure of the landfill groundwater did not clearly show a significant correlation with the distance from well LF2B. Burkholderia sp. and Pseudomonas sp. were found to be the dominant microbial populations detected in all wells, while Bradyrhizobium sp. and Ralstonia sp. were dominant populations for seven wells except LF2B. In addition, Mantel test and canonical correspondence analysis (CCA) indicate that pH, sulfate, ammonia nitrogen and dissolved organic carbon (DOC) have significant effects on the microbial community structure. The results suggest that the leachate from unlined landfills significantly impact the structures of groundwater microbial communities, and that more distal wells recover by natural attenuation.« less

Isotopic and geochemical tracers for U(VI) reduction and U mobility at an in situ recovery U mine

DOE PAGES

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

2015-05-19

In situ recovery (ISR) uranium (U) mining mobilizes U in its oxidized hexavalent form (U(VI)) by oxidative dissolution of U from the roll-front U deposits. Post-mining natural attenuation of residual U(VI) at ISR mines is a potential remediation strategy. Detection and monitoring of naturally occurring reducing subsurface environments are important for successful implementation of this remediation scheme. We used the isotopic tracers ²³⁸U/²³⁵U (δ²³⁸U), ²³⁴U/²³⁸U activity ratio, and ³⁴S/³²S (δ³⁴S), and geochemical measurements of U ore and groundwater collected from 32 wells located within, upgradient, and downgradient of a roll-front U deposit to detect U(VI) reduction and U mobility atmore » an ISR mining site at Rosita, TX, USA. The δ²³⁸U in Rosita groundwater varies from 0.61‰ to -2.49‰, with a trend toward lower δ²³⁸U in downgradient wells. The concurrent decrease in U(VI) concentration and δ²³⁸U with an ε of 0.48‰ ± 0.08‰ is indicative of naturally occurring reducing environments conducive to U(VI) reduction. Additionally, characteristic ²³⁴U/²³⁸U activity ratio and δ³⁴S values may also be used to trace the mobility of the ore zone groundwater after mining has ended. These results support the use of U isotope-based detection of natural attenuation of U(VI) at Rosita and other similar ISR mining sites.« less

Isotopic and geochemical tracers for U(VI) reduction and U mobility at an in situ recovery U mine

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

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

In situ recovery (ISR) uranium (U) mining mobilizes U in its oxidized hexavalent form (U(VI)) by oxidative dissolution of U from the roll-front U deposits. Post-mining natural attenuation of residual U(VI) at ISR mines is a potential remediation strategy. Detection and monitoring of naturally occurring reducing subsurface environments are important for successful implementation of this remediation scheme. We used the isotopic tracers ²³⁸U/²³⁵U (δ²³⁸U), ²³⁴U/²³⁸U activity ratio, and ³⁴S/³²S (δ³⁴S), and geochemical measurements of U ore and groundwater collected from 32 wells located within, upgradient, and downgradient of a roll-front U deposit to detect U(VI) reduction and U mobility atmore » an ISR mining site at Rosita, TX, USA. The δ²³⁸U in Rosita groundwater varies from 0.61‰ to -2.49‰, with a trend toward lower δ²³⁸U in downgradient wells. The concurrent decrease in U(VI) concentration and δ²³⁸U with an ε of 0.48‰ ± 0.08‰ is indicative of naturally occurring reducing environments conducive to U(VI) reduction. Additionally, characteristic ²³⁴U/²³⁸U activity ratio and δ³⁴S values may also be used to trace the mobility of the ore zone groundwater after mining has ended. These results support the use of U isotope-based detection of natural attenuation of U(VI) at Rosita and other similar ISR mining sites.« less

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

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.

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.

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.

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

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

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.

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

LaFreniere, L. M.; Environmental Science Division

The 2006-2007 investigation of carbon tetrachloride and chloroform contamination at Barnes, Kansas, was conducted at the request of the Kansas Department of Health and Environment (KDHE). The Environmental Science Division of Argonne National Laboratory implemented the investigation on behalf of the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA). The overall goal of the investigation was to establish criteria for monitoring leading to potential site reclassification. The investigation objectives were to (1) determine the hydraulic gradient near the former CCC/USDA facility, (2) delineate the downgradient carbon tetrachloride plume, and (3) design and implement an expanded monitoring network atmore » Barnes (Argonne 2006a).« less

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

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).

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.

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

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.

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

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

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

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

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

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

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.

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

Not Available

The Army Creek Landfill (ACL), formerly known as the Llangollen Landfill, is located approximately two miles southwest of New Castle, Delaware, and is adjacent to the Delaware Sand and Gravel Landfill Superfund site. The County operated this 44-acre landfill, which accepted municipal wastes, from 1960 until its closure in 1968 when it was filled to capacity. In late 1971, water in a residential well downgradient of the site developed quality problems. Results from a subsequent investigation showed that leachate, most likely originating from the Army Creek and Delaware Sand and Gravel Landfills, was contaminating local aquifers. This lead to themore » installation of a ground water recovery system designed to maintain a ground water divide between the landfills and the Artesian Water Company Wellfield located downgradient of the landfills. The primary contaminants of concern include: VOCs, inorganics, heavy metals, benzene, and chromium.« less

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...

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 ...

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.

Wilson Corners SWMU 001 2015 Annual Long Term Monitoring Report Kennedy Space Center, Florida

NASA Technical Reports Server (NTRS)

Lawson, Emily M.

2016-01-01

This document presents the findings of the 2015 Long Term Monitoring (LTM) that was completed at the Wilson Corners site, located at the National Aeronautics and Space Administration John F. Kennedy Space Center, Florida. The objectives of the 2015 LTM event were to evaluate the groundwater flow direction and gradient, to monitor the vertical and horizontal extent of the volatile organic compounds (VOCs; including the upgradient and sidegradient extents, which are monitored every five years), and to monitor select locations internal to the dissolved groundwater plume. The 2015 LTM event included several upgradient and sidegradient monitoring wells that are not sampled annually to verify the extent of VOCs in this portion of the site. The December 2015 LTM groundwater sampling event included, depth to groundwater measurements, 40 VOC samples collected using passive diffusion bags, and one VOC sample collected using low-flow techniques. Additionally, monitoring well MW0052DD was overdrilled and abandoned using rotasonic drilling techniques. The following conclusions can be made based on the 2015 LTM results: groundwater flow is generally to the west with northwest and southwest flow components from the water table to approximately 55 feet below land surface (ft BLS); peripheral monitoring wells generally delineate VOCs to groundwater cleanup target levels (GCTLs) except for monitoring wells MW0088, MW0090, MW0095, and NPSHMW0039, which had vinyl chloride (VC) concentrations near the GCTL and MW0062, which had trichloroethene (TCE), cis-1,2-dichloroethenen (cDCE), and VC concentrations above natural attenuation default concentrations (NADCs); VOCs in interior downgradient wells generally fluctuate within historic ranges except for monitoring wells in the north-northwest portion of the site, which have increasing VC concentrations indicating potential plume migration and expansion; Historically, the vertical extents of the VOCs were delineated by monitoring wells screened greater than 60 ft BLS (MW0083 through MW0086, and MW0078). The 2015 LTM results indicate that concentrations of daughter product cDCE is greater than the NADC in MW0078 and that cDCE and VC are greater than NADCs in MW0130. TCE was greater than the GCTL in monitoring well MW130 and not detected above method detection limits (9 micrograms per Liter) in monitoring well MW0078. No GCTL exceedances were identified in monitoring wells MW0083 or MW0086; the dissolved plume footprint appears generally stable, though not fully delineated by monitoring well data in the northeast portion of the site; and 2015 LTM results generally support the existing Conceptual Site Model. Geosyntec recommends modifying the LTM program, collecting a verification sample from monitoring well MW0062, and performing a direct push technology instigation in the northnortheastern portion of the site. A cluster of monitoring wells (MW0132 [2 to 12 ft BLS], MW0133 [15 to 25 ft BLS], and MW0134 [29 to 34 ft BLS]) is proposed to delineate impacts in the northnortheast portion of the site. Geosyntec recommends installation of a vertical extent well in the center of the site (Hot Spot 2 area) post-remediation implementation.

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.

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.

Thermal management of an unconsolidated shallow urban groundwater body

NASA Astrophysics Data System (ADS)

Epting, J.; Händel, F.; Huggenberger, P.

2013-05-01

This study presents the development of tools for the sustainable thermal management of a shallow unconsolidated urban groundwater body in the city of Basel (Switzerland). The concept of the investigations is based on (1) a characterization of the present thermal state of the urban groundwater body, and (2) the evaluation of potential mitigation measures for the future thermal management of specific regions within the groundwater body. The investigations focus on thermal processes down-gradient of thermal groundwater use, effects of heated buildings in the subsurface as well as the thermal influence of river-groundwater interaction. Investigation methods include (1) short- and long-term data analysis, (2) high-resolution multilevel groundwater temperature monitoring, as well as (3) 3-D numerical groundwater flow and heat transport modeling and scenario development. The combination of these methods allows for the quantifying of the thermal influences on the investigated urban groundwater body, including the influences of thermal groundwater use and heated subsurface constructions. Subsequently, first implications for management strategies are discussed, including minimizing further groundwater temperature increase, targeting "potential natural" groundwater temperatures for specific aquifer regions and exploiting the thermal potential.

Application of Biostimulation for Remediation of Sulfate-Contaminated Groundwater at a Mining Site

NASA Astrophysics Data System (ADS)

Miao, Z.; Carroll, K. C.; Carreon, C.; Brusseau, M. L.

2011-12-01

There is growing concern regarding sulfate contamination of groundwater. One innovative in-situ remediation option under investigation is biostimulation through addition of electron-donor amendments to enhance sulfate reduction. Two pilot-scale ethanol-injection tests were conducted at a former uranium mining site that is contaminated with sulfate and nitrate (with a lack of heavy metals), and for which there appears to be minimal natural attenuation of sulfate. The first test was a push-pull test that had a limited zone of influence, while the second test was a single-well injection test in which additional downgradient wells were monitored. For both tests, sulfate concentrations began to decline within a few weeks of injection, after nitrate concentrations were significantly reduced. Concomitantly, aqueous concentrations of manganese, iron, and hydrogen sulfide increased from background. Monitoring over many months revealed that the declines in sulfate concentration conformed to exponential decay, with first-order decay rates of approximately 0.01 /d. Analysis of sulfur stable isotope data indicated that the decrease in sulfate concentrations was microbially mediated. The results also indicated that sulfides formed during sulfate reduction may have undergone partial re-oxidation. This study illustrates the feasibility of using ethanol injection for remediation of sulfate-contaminated groundwater. However, re-oxidation of sulfides (both metal sulfide precipitates and hydrogen sulfide gas) is a potential issue of significance that would need to be addressed.

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.

Groundwater chemistry in the vicinity of the Puna Geothermal Venture Power Plant, Hawai‘i, after two decades of production

USGS Publications Warehouse

Evans, W.C.; Bergfeld, D.; Sutton, A.J.; Lee, R.C.; Lorenson, T.D.

2015-01-01

We report chemical data for selected shallow wells and coastal springs that were sampled in 2014 to determine whether geothermal power production in the Puna area over the past two decades has affected the characteristics of regional groundwater. The samples were analyzed for major and minor chemical species, trace metals of environmental concern, stable isotopes of water, and two organic compounds (pentane and isopropanol) that are injected into the deep geothermal reservoir at the power plant. Isopropanol was not detected in any of the groundwaters; confirmed detection of pentane was restricted to one monitoring well near the power plant at a low concentration not indicative of source. Thus, neither organic compound linked geothermal operations to groundwater contamination, though chemical stability and transport velocity questions exist for both tracers. Based on our chemical analysis of geothermal fluid at the power plant and on many similar results from commercially analyzed samples, we could not show that geothermal constituents in the groundwaters we sampled came from the commercially developed reservoir. Our data are consistent with a long-held view that heat moves by conduction from the geothermal reservoir into shallow groundwaters through a zone of low permeability rock that blocks passage of geothermal water. The data do not rule out all impacts of geothermal production on groundwater. Removal of heat during production, for example, may be responsible for minor changes that have occurred in some groundwater over time, such as the decline in temperature of one monitoring well near the power plant. Such indirect impacts are much harder to assess, but point out the need for an ongoing groundwater monitoring program that should include the coastal springs down-gradient from the power plant.

Installation Restoration Program. Phase II. Confirmation/Quantification. Stage 1 for Hancock Field, New York and HQTAC, Langley AFB, Virginia.

DTIC Science & Technology

1984-10-01

resulting from previous waste disposal practices at Hancock Field o Recommend measures to mitigatc, adverse impacts at identified contaminated areas o...well GW-8 is downgradient of both disposal sites and this will be the best well to use in judging water quality impacts caused by the disposal...groundwater quality and quantity samples. The amount of water added to each well was in the order of 2 to 4 gallons. This should not adversely impact

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.

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

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.

In Situ Biotreatment of TBA with Recirculation/Oxygenation

PubMed Central

North, Katharine P.; Mackay, Douglas M.; Kayne, Julian S.; Petersen, Daniel; Rasa, Ehsan; Rastegarzadeh, Laleh; Holland, Reef B.; Scow, Kate M.

2012-01-01

The potential for in situ biodegradation of tert-butyl alcohol (TBA) by creation of aerobic conditions in the subsurface with recirculating well pairs was investigated in two field studies conducted at Vandenberg Air Force Base (VAFB). In the first experiment, a single recirculating well pair with bromide tracer and oxygen amendment successfully delivered oxygen to the subsurface for 42 days. TBA concentrations were reduced from approximately 500 μg/L to below the detection limit within the treatment zone and the treated water was detected in a monitoring transect several meters downgradient. In the second experiment, a site-calibrated model was used to design a double recirculating well pair with oxygen amendment, which successfully delivered oxygen to the subsurface for 291 days and also decreased TBA concentrations to below the detection limit. Methylibium petroleiphilum strain PM1, a known TBA-degrading bacterium, was detectable at the study site but addition of oxygen had little impact on the already low baseline population densities, suggesting that there was not enough carbon within the groundwater plume to support significant new growth in the PM1 population. Given favorable hydrogeologic and geochemical conditions, the use of recirculating well pairs to introduce dissolved oxygen into the subsurface is a viable method to stimulate in situ biodegradation of TBA or other aerobically-degradable aquifer contaminants. PMID:23358537

In Situ Biotreatment of TBA with Recirculation/Oxygenation.

PubMed

North, Katharine P; Mackay, Douglas M; Kayne, Julian S; Petersen, Daniel; Rasa, Ehsan; Rastegarzadeh, Laleh; Holland, Reef B; Scow, Kate M

2012-01-01

The potential for in situ biodegradation of tert-butyl alcohol (TBA) by creation of aerobic conditions in the subsurface with recirculating well pairs was investigated in two field studies conducted at Vandenberg Air Force Base (VAFB). In the first experiment, a single recirculating well pair with bromide tracer and oxygen amendment successfully delivered oxygen to the subsurface for 42 days. TBA concentrations were reduced from approximately 500 μg/L to below the detection limit within the treatment zone and the treated water was detected in a monitoring transect several meters downgradient. In the second experiment, a site-calibrated model was used to design a double recirculating well pair with oxygen amendment, which successfully delivered oxygen to the subsurface for 291 days and also decreased TBA concentrations to below the detection limit. Methylibium petroleiphilum strain PM1, a known TBA-degrading bacterium, was detectable at the study site but addition of oxygen had little impact on the already low baseline population densities, suggesting that there was not enough carbon within the groundwater plume to support significant new growth in the PM1 population. Given favorable hydrogeologic and geochemical conditions, the use of recirculating well pairs to introduce dissolved oxygen into the subsurface is a viable method to stimulate in situ biodegradation of TBA or other aerobically-degradable aquifer contaminants.

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.

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.

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.

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.

Data Validation Package, July 2016 Groundwater Sampling at the Shirley Basin South, Wyoming, Disposal Site November 2016

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

Frazier, William; Price, Jeffrey

Sampling Period: July 14-15, 2016 The 2004 Long-Term Surveillance Plan for the Shirley Basin South (UMTRCA Title II) Disposal Site, Carbon County, Wyoming, requires annual monitoring to verify continued compliance with the pertinent alternate concentration limits (ACLs) and Wyoming Class III (livestock use) groundwater protection standards. Planned monitoring locations are shown in Attachment 1, Sampling and Analysis Work Order. Point-of-compliance (POC) wells 19-DC, 5-DC, and 5-SC, and monitoring wells 10-DC, 110-DC, 112-DC, 113-DC, 40-SC, 54-SC, 100-SC, 102-SC, and K.G.S.#3 were sampled. POC well 51-SC and downgradient well 101-SC were dry at the time of sampling. The water level was measuredmore » at each sampled well. See Attachment 2, Trip Report for additional details. Sampling and analyses were conducted in accordance with the Sampling and Analysis Plan for the U S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated, http://energy.gov/lm/downloads/sampling-and­ analysis-plan-us-department-energy-office-legacy-management-sites). ACLs are approved for cadmium, chromium, lead, nickel, radium-226, radium-228, selenium, thorium-230, and uranium in site groundwater. Time-concentration graphs of the contaminants of concern in POC wells are included in Attachment 3, Data Presentation. The only ACL exceedance in a POC well was radium-228 in well 5-DC where the concentration was 30.7 picocuries per liter (pCi/L), exceeding the ACL of 25.7 pCi/L. Concentrations of sulfate and total dissolved solids continue to exceed their respective Wyoming Class III groundwater protection standards for livestock use in wells 5-DC, 5-SC, and 54-SC as they have done throughout the sampling history; however, there is no livestock use of the water from these aquifers at the site, and no constituent concentrations exceed groundwater protection standards at the wells near the site boundary.« less

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.

Final report : groundwater monitoring at Morrill, Kansas, in September 2005 and March 2006, with expansion of the monitoring network in January 2006.

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

LaFreniere, L. M.; Environmental Science Division

2007-06-30

This document reports the results of groundwater monitoring in September 2005 and March 2006 at the grain storage facility formerly operated at Morrill, Kansas, by the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA). These activities were the first and second twice yearly sampling events of the two-year monitoring program approved by the CCC/USDA and Kansas Department of Health and Environment (KDHE) project managers. The monitoring network sampled in September 2005 consisted of 9 monitoring wells (MW1S-MW5S and MW1D [installed in the mid 1990s] and MW6S-MW8S [installed in 2004]), plus 3 private wells (Isch, Rillinger, and Stone). Themore » groundwater samples collected in this first event were analyzed for volatile organic compounds (VOCs), dissolved hydrogen, and additional groundwater parameters to aid in evaluating the potential for reductive dechlorination processes. After the monitoring in September 2005, Argonne recommended expansion of the initial monitoring network. Previous sampling (August 2004) had already suggested that the initial network was inadequate to delineate the extent of the carbon tetrachloride plume. With the approval of the CCC/USDA and KDHE project managers, the monitoring network was expanded in January 2006 through the installation of 3 additional monitoring wells (MW9S-MW11S). Details of the monitoring well installations are reported in this document. The expanded monitoring network of 12 monitoring wells (MW1S-MW11S and MW1D) and 3 private wells (Isch, Rillinger, and Stone) was sampled in March 2006, the second monitoring event in the planned two-year program. Results of analyses for VOCs showed minor increases or decreases in contaminant levels at various locations but indicated that the leading edge of the contaminant plume is approaching the intermittent stream leading to Terrapin Creek. The groundwater samples collected in March 2006 were also analyzed for additional groundwater parameters to aid in the evaluation of the potential for reductive dechlorination processes. Preliminary screening of groundwater parameters provided inadequate evidence that reductive dechlorination of carbon tetrachloride is taking place at some locations on the former CCC/USDA property. Groundwater levels measured manually in October 2005, March 2006, and June 2006 were used to map the potentiometric surface at Morrill. The results were generally consistent with each other and with previous measurements, indicating a groundwater flow direction to the south-southeast from the former CCC/USDA facility. Data recorders installed in wells MW1S-MW8S in July 2004 are gathering long-term data on the groundwater elevation and gradient. Data downloaded in August 2004, March 2005, October 2005, and June 2006 indicate that two relatively upgradient wells near the former CCC/USDA facility responded distinctly to apparent rainfall/recharge events. In contrast, two downgradient wells south of the former facility showed virtually no response, probably because of the damping influence of the nearby surface drainages and shallow groundwater at their locations. The first two monitoring events of the planned two-year monitoring program for Morrill have demonstrated no clear pattern of changes in carbon tetrachloride concentrations, though the contaminated zone has expanded toward the intermittent stream. Argonne recommends that the monitoring program continue as approved and that surface water samples be collected in future monitoring events (September 2006, March 2007, and September 2007).« less

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.

RESULTS OF TRITIUM TRACKING AND GROUNDWATER MONITORING AT THE HANFORD SITE 200 AREA STATE APPROVED LAND DISPOSAL SITE FY2008

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

ERB DB

2008-11-19

The Hanford Site's 200 Area Effluent Treatment Facility (ETF) processes contaminated aqueous wastes derived from Hanford Site facilities. The treated wastewater occasionally contains tritium, which cannot be removed by the ETF prior to the wastewater being discharged to the 200 Area State-Approved Land Disposal Site (SALDS). During the first 11 months of fiscal year 2008 (FY08) (September 1, 2007, to July 31, 2008), approximately 75.15 million L (19.85 million gal) of water were discharged to the SALDS. Groundwater monitoring for tritium and other constituents, as well as water-level measurements, is required for the SALDS by State Waste Discharge Permit Numbermore » ST-4500 (Ecology 2000). The current monitoring network consists of three proximal (compliance) monitoring wells and nine tritium-tracking wells. Quarterly sampling of the proximal wells occurred in October 2007 and in January/February 2008, April 2008, and August 2008. The nine tritium-tracking wells, including groundwater monitoring wells located upgradient and downgradient of the SALDS, were sampled in January through April 2008. Water-level measurements taken in the three proximal SALDS wells indicate that a small groundwater mound is present beneath the facility, which is a result of operational discharges. The mound increased in FY08 due to increased ETF discharges from treating groundwater from extraction wells at the 200-UP-l Operable Unit and the 241-T Tank Farm. Maximum tritium activities increased by an order of magnitude at well 699-48-77A (to 820,000 pCi/L in April 2008) but remained unchanged in the other two proximal wells. The increase was due to higher quantities of tritium in wastewaters that were treated and discharged in FY07 beginning to appear at the proximal wells. The FY08 tritium activities for the other two proximal wells were 68,000 pCi/L at well 699-48-77C (October 2007) and 120,000 pCi/L at well 699-48-77D (October 2007). To date, no indications of a tritium incursion from the SALDS have been detected in the tritium-tracking wells. Concentrations of all chemical constituents were within Permit limits or were below method detection limits when sampled during FY08. A summary of the chemical constituent concentrations or method detection limits is provided in Table 3-2 in the main text discussion. This report presents the results of groundwater monitoring and tritium-tracking samples from the SALDS facility during FY08. Due to the 30-day laboratory turnaround for analysis of proximal well groundwater samples, this report addresses available date extending from August 1, 2007, through September 30, 2008 (August 2007 data were not included in the FY07 report). Updated background information, which is necessary to understand the results of the groundwater analyses, is also provided on facility operations. Interpretive discussions and recommendations for future monitoring are also provided, where possible.« less

Evaluation of bromide mass discharge in a sandy aquifer at Vandenberg AFB, CA

NASA Astrophysics Data System (ADS)

Mackay, D. M.; Rasa, E.; Einarson, M.; Kaiser, P.; Chakraborty, I.; Scow, K. M.

2009-12-01

Side-by-side experiments were conducted by UC Davis research team at a former fuel station at Vandenberg Air Force Base (AFB) to evaluate the rate of transformation of methyl tert-butyl ether (MTBE) to tert-butyl alcohol (TBA) impacted by ethanol and to investigate evidence of TBA degradation under sulfate reducing conditions. On one side we injected groundwater amended with ethanol and MTBE. In the other lane we injected groundwater amended with TBA. On both sides, injected ground water was spiked with bromide tracer to provide estimates of groundwater flow direction variations, flow velocity, dispersion, and mobile mass loss resulting from diffusive sequestration into aquitards. 162 monitoring wells were aligned into seven transects located downgradient of the injection wells. The mass discharge approach was used to evaluate the natural attenuation of the injected constituents. In this talk we will focus on calculations of mass discharge of the bromide tracer at each of the seven monitoring well transects. The amount of bromide mass discharged through each transect was calculated for any sampling time using field measurements of break through curves. Cumulative mass discharges were estimated and, by iteration based on mass balance, the flow properties of the aquifer were estimated. The calibration process resulted in subtle but quantitatively important changes in our assumptions regarding key physical properties of the aquifer (thickness, porosity) which could be only approximately estimated by standard methods (coring, CPT, etc.). On the basis of this calibration, a more robust approach was devised for evaluating the source and fate of TBA in the aquifer.

Thermal management of an urban groundwater body

NASA Astrophysics Data System (ADS)

Epting, J.; Huggenberger, P.

2012-06-01

This study presents a management concept for the sustainable thermal use of an urban groundwater body. The concept is designed to be applied for shallow thermal groundwater use and is based on (1) a characterization of the present thermal state of the investigated urban groundwater body; (2) the definition of development goals for specific aquifer regions, including future aquifer use and urbanization; and (3) an evaluation of the thermal use potential for these regions. The investigations conducted in the city of Basel (Switzerland) focus on thermal processes down-gradient of thermal groundwater use, effects of heated buildings in the aquifer as well as the thermal influence of river-groundwater interaction. Investigation methods include: (1) short- and long-term data analysis; (2) high-resolution multilevel groundwater temperature monitoring; as well as (3) 3-D numerical groundwater flow and heat-transport modeling and scenario development. The combination of these methods allows quantifying the thermal influence on the investigated urban groundwater body, including the influences of thermal groundwater use and additional heat from urbanization. Subsequently, management strategies for minimizing further groundwater temperature increase, targeting "potential natural" groundwater temperatures for specific aquifer regions and exploiting the thermal use potential are discussed.

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

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.

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.

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

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.

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,

Preliminary characterization of nitrogen and phosphorus in groundwater discharging to Lake Spokane, northeastern Washington, using stable nitrogen isotopes

USGS Publications Warehouse

Gendaszek, Andrew S.; Cox, Stephen E.; Spanjer, Andrew R.

2016-02-29

Lake Spokane, locally referred to as Long Lake, is a 24-mile-long section of the Spokane River impounded by Long Lake Dam that has, in recent decades, experienced water-quality problems associated with eutrophication. Consumption of oxygen by the decomposition of aquatic plants that have proliferated because of high nutrient concentrations has led to seasonally low dissolved oxygen concentrations in the lake. Of nitrogen and phosphorus, the two primary nutrients necessary for aquatic vegetation growth, phosphorus was previously identified as the limiting nutrient that regulates the growth of aquatic plants and, thus, dissolved oxygen concentrations in Lake Spokane. Phosphorus is delivered to Lake Spokane from municipal and industrial point-source inputs to the Spokane River upstream of Lake Spokane, but is also conveyed by groundwater and surface water from nonpoint-sources including septic tanks, agricultural fields, and wildlife. In response, the Washington State Department of Ecology listed Lake Spokane on the 303(d) list of impaired water bodies for low dissolved oxygen concentrations and developed a Total Maximum Daily Load for phosphorus in 1992, which was revised in 2010 because of continuing algal blooms and water-quality concerns.This report evaluates the concentrations of phosphorus and nitrogen in shallow groundwater discharging to Lake Spokane to determine if a difference exists between nutrient concentrations in groundwater discharging to the lake downgradient of residential development with on-site septic systems and downgradient of undeveloped land without on-site septic systems. Elevated nitrogen isotope values (δ15N) within the roots of aquatic vegetation were used as an indicator of septic-system derived nitrogen. δ15N values were measured in August and September 2014 downgradient of residential development near the lakeshore, of residential development on 300-ft-high terraces above the lake, and of undeveloped land in the eastern (upper) and central (lower) parts of Lake Spokane. Significantly lower δ15N values were measured within aquatic vegetation downgradient of undeveloped land in eastern Lake Spokane relative to both near-shore and terrace residential development land uses. Conversely, significantly higher δ15N values were measured downgradient of undeveloped land in central Lake Spokane relative to the two developed land uses. These results guided the location of subsequent groundwater sampling in March and April 2015 from 30 shallow piezometers driven into the near-shore area of Lake Spokane. Nitrate plus nitrite concentrations in groundwater discharging to Lake Spokane downgradient of undeveloped areas were significantly lower than those measured downgradient of both near-shore and terrace residential development. Orthophosphate concentrations in groundwater were not significantly different with respect to upgradient land use.

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.

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.

Distribution and potential health risk of groundwater uranium in Korea.

PubMed

Shin, Woosik; Oh, Jungsun; Choung, Sungwook; Cho, Byong-Wook; Lee, Kwang-Sik; Yun, Uk; Woo, Nam-Chil; Kim, Hyun Koo

2016-11-01

Chronic exposure even to extremely low specific radioactivity of natural uranium in groundwater results in kidney problems and potential toxicity in bones. This study was conducted to assess the potential health risk via intake of the groundwater containing uranium, based on the determination of the uranium occurrence in groundwater. The groundwater was investigated from a total of 4140 wells in Korea. Most of the groundwater samples showed neutral pH and (sub-)oxic condition that was influenced by the mixing with shallow groundwater due to long-screened (open) wells. High uranium contents exceeding the WHO guideline level of 30 μg L(-1) were observed in the 160 wells located mainly in the plutonic bedrock regions. The statistical analysis suggested that the uranium component was present in groundwater by desorption and re-dissolution processes. Predominant uranium phases were estimated to uranyl carbonates under the Korean groundwater circumstances. These mobile forms of uranium and oxic condition facilitate the increase of potential health risk downgradient. In particular, long-term intake of groundwater containing >200 μg U L(-1) may induce internal exposure to radiation as well as the effects of chemical toxicity. These high uranium concentrations were found in twenty four sampling wells of rural areas in this study, and they were mainly used for drinking. Therefore, the high-level uranium wells and neighboring areas must be properly managed and monitored to reduce the exposure risk for the residents by drinking groundwater. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

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.

Selected natural attenuation monitoring data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June 2002

USGS Publications Warehouse

Dinicola, Richard S.

2004-01-01

Previous investigations indicated that natural attenuation and biodegradation of chlorinated volatile organic compounds (CVOCs) are substantial in shallow ground water beneath the 9-acre former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center (NUWC), Division Keyport, Washington. The U.S. Geological Survey (USGS) has continued to monitor ground-water geochemistry to assure that conditions remain favorable for contaminant biodegradation. This report presents the geochemical and selected CVOC data for ground water at OU 1, collected by the USGS during June 10-14, 2002, in support of long-term monitoring for natural attenuation. Overall, the geochemical data for June 2002 indicate that redox conditions in the upper-aquifer water remain favorable for reductive dechlorination of chlorinated VOCs because strongly reducing conditions persisted beneath much of the former landfill. Redox conditions in the intermediate aquifer downgradient of the landfill also remained favorable for reductive dechlorination, although the 2002 dissolved hydrogen (H2) concentration from well MW1-28 is questionable. Changes in redox conditions were observed at certain wells during 2002, but a longer monitoring period and more thorough interpretation are needed to ascertain if phytoremediation activities are affecting redox conditions and if biodegradation processes are changing over time. The Navy intends to complete a more thorough interpretation in preparation for the 5-year review of OU 1 scheduled for 2004. There were a few substantial differences between the 2002 concentrations and previously observed concentrations of volatile organic compounds. Total CVOC concentrations in 2002 samples decreased substantially in all piezometers sampled in the northern plantation, and the largest percentages of decrease were for the compounds trichloroethene (TCE) and cis-1,2-dichloroethene (cis-DCE). Changes in total CVOC concentrations in the southern plantation were less consistent. Historically high concentrations were observed in samples from three piezometers, with particularly substantial increases in TCE and cis-DCE concentrations, and historically low concentrations were observed in two piezometers, with particularly substantial decreases in TCE and cis-DCE concentrations. Similarly to the redox chemistry, a longer monitoring period and more thorough interpretation are needed to ascertain if phytoremediation activities are affecting CVOC concentrations and if biodegradation processes are changing over time. No changes in monitoring plans are proposed for June 2003, although the practice of deploying a data sonde downhole while purging the wells will be discontinued. Downhole monitoring added uncertainty to selected measured dissolved H2 concentrations because of the possibility that the sonde and cable created a bridge that resulted in non-equilibrium dissolved H2 concentrations at the wells.

Consideration of Treatment Performance Assessment Metrics for a TCE Source Area Bioremediation (SABRe project)

NASA Astrophysics Data System (ADS)

Cai, Z.; Wilson, R. D.

2009-05-01

Techniques for optimizing the removal of NAPL mass in source zones have advanced at a more rapid rate than strategies to assess treatment performance. Informed selection of remediation approaches would be easier if measurements of performance were more directly transferable. We developed a number of methods based on data generated from multilevel sampler (MLS) transects to assess the effectiveness of a bioaugmentation/biostimulation trial in a TCE source residing in a terrace gravel aquifer in the East Midlands, UK. In this spatially complex aquifer, treatment inferred from long screen monitoring well data was not as reliable as that from consideration of mass flux changes across transects installed in and downgradient of the source. Falling head tests were conducted in the MLS ports to generate the necessary hydraulic conductivity (K) data. Combining K with concentration provides a mass flux map that allows calculation of mass turnover and an assessment of where in the complex geology the greatest turnover occurred. Five snapshots over a 600-day period indicate a marked reduction in TCE flux, suggesting a significant reduction in DNAPL mass over that expected due to natural processes. However, persistence of daughter products suggested that complete dechlorination did not occur. The MLS fence data also revealed that delivery of both carbon source and pH buffer were not uniform across the test zone. This may have lead to the generation of niches of iron(III) and sulphate reduction as well as methanogenesis, which impacted on dechlorination processes. In the absence of this spatial data, it is difficult to reconcile apparent treatment as indicated in monitoring well data to on-going processes.

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

KUBILIUS, WALTER

The origin of elevated radium-226 in groundwater beneath a sanitary landfill at the Savannah River Site (SRS) was investigated. Nearly one hundred monitoring wells are developed in the Steed Pond Aquifer (SPA), which consists of 100-150 ft of Coastal Plain sand, iron oxides, and minor clay. Wells screened in the upper and middle portions of the aquifer have average Ra-226 between 0.5 and 2.5 pCi/L, and average pHs above 4.7. However, wells screened near the base of the aquifer exhibit higher average Ra-226 concentrations of 2.5 to 4.6 pCi/L, with some measurements exceeding the MCL of 5 pCi/L, and showmore » average pHs of 4.1 to 4.7. These wells are not downgradient of the landfill, and are not impacted by landfill leachate. The Crouch Branch Confining Unit (CBCU) underlies the aquifer, and is composed partly of reduced gray/brown clay with lignite and authigenic pyrite. Gamma ray logs show that the SPA has low gamma counts, but the CBCU is consistently elevated. Groundwater with high radium/low pH also contains elevated sulfate concentrations. pH calculations indicate that sulfate is in the form of sulfuric acid. A model for the origin of elevated Ra-226 levels in deeper SPA wells envisions infiltration of oxygenated SPA groundwater into reduced pyritic CBCU sediments, with consequent oxidative pyrite dissolution, and acidification of groundwater. Then, naturally occurring CBCU radium dissolves, and mixes into the Steed Pond Aquifer.« less

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.

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)

An Enhanced Monitoring Network at the Central Nevada Test Area (CNTA) Work performed under U.S. Department of Energy Office of Legacy Management contract #DE-AM01-07LM00060

NASA Astrophysics Data System (ADS)

Hodges, R.; Findlay, R.; Kautsky, M.

2009-12-01

On January 19, 1968 the Atomic Energy Commission detonated a 200-1000 kt nuclear device at a depth of 975 meters at CNTA, approximately 100 miles north of the Nevada Test Site. Details of the detonation remain classified, including the specific yield and the size of the resultant cavity. Therefore, using the rough, generic relationships between yield and cavity size, yield and depth of burial, and cancelling out yield, leads to an estimated cavity radius of 100 meters for this detonation in the volcanic section. A collapse chimney subsequently formed that extended several hundred meters above the detonation into the overlying alluvium. The detonation reactivated several faults at the site and created a 2 km2 graben at the surface. The radionuclides in the detonation zone are a potential source of groundwater contamination. The most permeable unit near the detonation zone through which transport might occur is believed to be a densely welded tuff unit (DWT) below the detonation level. A three-well monitoring network was designed using a numerical model, and data were collected from the wells for comparison with model predictions. The head data from the wells were not in agreement with those predicted by the model, and the model was not validated. In a positive finding for radionuclide containment, aquifer test results from the new wells indicate that the DWT is less permeable than previously expected and suggest that the contaminant boundary developed from the model is likely conservative for predicting transport within the volcanic section. The overlying alluvial aquifer is not believed to be a migration pathway for significant quantities of radionuclides, though it is the most likely pathway to potential receptors in that it is the primary groundwater source in the area. To enhance the CNTA monitoring network, two new alluvial wells were installed in 2009, downgradient (east-southeast and south-southeast) of the detonation. The dual-completion alluvial wells were designed to not only monitor for radionuclides but also to determine if a southeast-bounding graben fault acts as a flow barrier. A seismic survey was conducted to optimally locate the wells with respect to the fault. The survey imaged the water table and showed offsets of the water table reflector at numerous faults; some of the faults were known and others had not been previously recognized. Water levels from the new alluvial wells and piezometers compare well with existing well data and support the conjecture that the southeast-bounding graben fault is a flow barrier. Over the last five years, a monitoring network at CNTA has been developed that monitors both the most likely migration pathway and the most likely pathway to potential receptors. The site investigation processes discussed here have also identified factors that affect groundwater flow at the site, and the methods employed can be used in similar hydrogeologic environments.

Data Validation Package November 2015 Groundwater and Surface Water Sampling at the Old and New Rifle, Colorado, Processing Sites February 2016

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

Bush, Richard; Lemke, Peter

Water samples were collected from 36 locations at New Rifle and Old Rifle, Colorado, Processing Sites. Duplicate samples were collected from New Rifle locations 0659 and 0855, and Old Rifle location 0304. One equipment blank was collected after decontamination of non-dedicated equipment used to collect one surface water sample. 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). New Rifle Site Samples were collected at the New Rifle site from 16 monitoring wells and 7 surface locations in compliance with the December 2008more » Groundwater Compliance Action Plan [GCAP] for the New Rifle, Colorado, Processing Site (LMS/RFN/S01920), with one exception: New Rifle location 0635 could not be sampled because it was inaccessible; a fence installed by the Colorado Department of Transportation prevents access to this location. DOE is currently negotiating access with the Colorado Department of Transportation. Analytes measured at the New Rifle site included contaminants of concern (COCs) (arsenic, molybdenum, nitrate + nitrite as nitrogen, selenium, uranium, and vanadium) ammonia as nitrogen, major cations, and major anions. Field measurements of total alkalinity, oxidation- reduction potential, pH, specific conductance, turbidity, and temperature were made at each location, and the water level was measured at each sampled well. A proposed alternate concentration limit (ACL) for vanadium of 50 milligrams per liter (mg/L), specific to the compliance (POC) wells (RFN-0217, -0659, -0664, and -0669) is included in the New Rifle GCAP. Vanadium concentrations in the POC wells were below the proposed ACL as shown in the time-concentration graphs in the Data Presentation section (Attachment 2). Time-concentration graphs from all other locations sampled are also included in Attachment 2. Sampling location RFN-0195 was misidentified for the June/August 2014 and November 2014 sampling events. (Well RFN-0609 was inadvertently sampled instead of RFN-0195 in 2014.) The results for RFN-0195 have been corrected, and are included in associated time-concentration graphs for this location. Recent results for RFN-0195 are consistent with established trends with the possible exception of vanadium. The most recent result for vanadium showed an increase over recent values. Vanadium concentrations at RFN-0195 and other locations will continue to be evaluated in the future to determine the potential for deviations from established trends. The surface water locations were sampled to monitor the impact of groundwater discharge. COC concentrations at Colorado River surface water locations RFN-0324 and RFN-0326, downgradient of the site, remained low and were consistent with historical results, as shown in the time-concentration graphs. COC concentrations did not indicate there are any impacts related to groundwater discharge to the river. In many cases, elevated COC concentrations at the New Rifle site pond locations were observed, as shown in the time-versus concentration graphs. As noted in the GCAP, this indicates impacts from groundwater discharge to the ponds. Old Rifle Site Samples were collected at the Old Rifle site from eight monitoring wells and five surface locations in compliance with the December 2001 Groundwater Compliance Action Plan for the Old Rifle, Colorado, UMTRA Project Site (GJ0-2000-177-TAR). Analytes measured at the Old Rifle site included COCs (selenium, uranium, and vanadium), major cations, and major anions. Field measurements of total alkalinity, oxidation-reduction potential, pH, specific conductance, turbidity, temperature, were made at each location, and the water level was measured at each sampled well. The monitoring strategy described in the GCAP is designed to determine progress of the natural flushing process in meeting compliance standards for site COCs. Standards for selenium and vanadium are the proposed ACLs of0.05 mg/L and 1.0 mg/L, respectively. For uranium the cleanup goal is the UMTRA standard of 0.044 mg/L or background, whichever is higher. As shown in the time concentration graphs, the uranium concentration exceeds the cleanup goal at groundwater monitoring locations RF0-0304, -0305, -0310, -0655, and -0656. The surface water locations were sampled to monitor the impact of groundwater discharge at Colorado River surface water locations adjacent to (RF0-0396) and downgradient of the site (RF0-0741). COC concentrations remain low and consistent with historical concentrations as shown in the time-concentration graphs (Attachment 2), which indicate no impacts from groundwater discharge to the river.« less

317/319 Phytoremediation site monitoring report - 2009 growing season : final report.

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

Negri, C .N.; Benda, P. L.; Gopalakrishnan, G.

2010-02-10

In 1999, Argonne National Laboratory (Argonne) designed and installed a series of engineered plantings consisting of a vegetative cover system and approximately 800 hybrid poplars and willows rooting at various predetermined depths. The plants were installed using various methods including Applied Natural Science's TreeWell{reg_sign} system. The goal of the installation was to protect downgradient surface and groundwater by intercepting the contaminated groundwater with the tree roots, removing moisture from the upgradient soil area, reducing water infiltration, preventing soil erosion, degrading and/or transpiring the residual volatile organic compounds (VOCs), and removing tritium from the subsoil and groundwater. This report presents themore » results of the monitoring activities conducted by Argonne's Energy Systems (ES) Division in the growing season of 2009. Monitoring of the planted trees began soon after the trees were installed in 1999 and has been conducted every summer since then. As the trees grew and consolidated their growth into the contaminated soil and groundwater, their exposure to the contaminants was progressively shown through tissue sampling. During the 2009 sampling campaign, VOC concentrations found in the French Drain area were in general consistent with or slightly lower than the 2008 results. Additionally, closely repeated, stand wide analyses showed contaminant fluctuations that may indicate short-term contaminant depletion in the area of interest of roots. This data will be useful to determine short-term removal rate by the trees. As in previous years, levels in the Hydraulic Control Area were close to background levels except for a few exceptions.« less

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.

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.

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

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)

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.

Biodegradation of crude oil into nonvolatile organic acids in a contaminated aquifer near Bemidji, Minnesota

USGS Publications Warehouse

Thorn, K.A.; Aiken, G.R.

1998-01-01

As the result of a pipeline burst, a body of light aliphatic crude oil floats atop the groundwater in a shallow sand and gravel aquifer in a remote area outside Bemidji, Minnesota. Biodegradation has resulted in the formation of a plume of DOC downgradient from the oil body. Groundwater has also been contaminated in an area known as the spray zone, from vertical infiltration of DOC resulting from biodegradation of crude oil in the overlying unsaturated zone. The majority of DOC in the contaminated groundwater is in the form of nonvolatile organic acids (NVOA's) which represent the partial oxidation products of the crude oil constituents. The NVOA's have been classified into three fractions according to their isolation on XAD resins: hydrophobic neutrals (HPO-N), hydrophobic acids (HPO-A) and hydrophilic acids (HPI-A). These fractions of NVOA's were isolated from a well downgradient from the oil body (well 530; DOC=21 mg C/l), from a well in the spray zone (well 603; DOC=15 mg C/l) and from an uncontaminated well upgradient of the oil body where the naturally occurring DOC is 2.9 mg C/l (well 310). The three sets of NVOA's were characterized by elemental analyses, molecular weight determinations, 14C ages and liquid phase 1H and 13C NMR. The crude oil and the saturate, aromatic, resin and asphaltene fractions of the crude oil were similarly analyzed by elemental analysis and NMR. The NVOA's from the contaminated wells were clearly distinguishable from the naturally occurring groundwater DOC. Based upon molecular weights, sulfur contents, aromaticities and the presence of methyl groups bonded to aromatic rings, the characterization data suggests that the NVOA's originate from the C18 or greater alkylaromatic, naphthenoaromatic and sulfur-containing constituents of the crude oil, including possibly the resins and asphaltenes.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

Impacts of Residual Surfactant on Tetrachloroethene (PCE) Degradation Following Pilot-Scale SEAR Treatment at a Chloroethene-Impacted Site

NASA Astrophysics Data System (ADS)

Ramsburg, C. A.; Abriola, L. M.; Pennell, K. D.; Löffler, F. E.; Gamache, M.; Petrovskis, E. A.

2003-04-01

A pilot-scale surfactant-enhanced aquifer remediation (SEAR) demonstration was completed during the summer of 2000 at the Bachman Road site (Oscoda, MI USA). For this test, an aqueous solution of 60 g/L Tween 80 (polyoxyethylene (20) sorbitan monooleate) was used to recover tetrachloroethene (PCE) from a suspected source zone, located underneath a former dry-cleaning facility. Tween 80 was selected for use based upon its demonstrated capacity to solubilize PCE, “food-grade” status, and biodegradative potential. Hydraulic control was maintained throughout the test, with 95% of the injected surfactant mass recovered by a single extraction well. Source-zone monitoring conducted 15 months after SEAR treatment revealed the presence of previously undetected volatile fatty acids (acetate and formate) and PCE degradation products (trichloroethene, cis-1,2-dichloroethene, trans-1,2-dichlorethene, and vinyl chloride), in conjunction with PCE concentration reductions of approximately two orders-of-magnitude. The detection of volatile fatty acids is relevant, as they are likely fermentation products of residual Tween 80. Microbial reductive dechlorination is limited by available electron donors, and microcosm studies demonstrated that both acetate and formate support reductively dechlorinating populations present at the oligotrophic Bachman Road site aquifer. Surfactant transport simulations, using a regional flow model developed for the site, were employed to determine appropriate down-gradient monitoring locations. Drive point samples taken 15 months post-treatment in the vicinity of the simulated residual surfactant plume, contained elevated concentrations of acetate and PCE daughter products. Ongoing efforts include continued site-monitoring, and microcosm studies to corroborate a causal relationship between Tween 80 fermentation and PCE dechlorination.

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.

A Case Study of Using Zero-Valent Iron Nanoparticles for Groundwater Remediation

NASA Astrophysics Data System (ADS)

Xiong, Z.; Kaback, D.; Bennett, P. J.

2011-12-01

Zero-valent iron nanoparticle (nZVI) is a promising technology for rapid in situ remediation of numerous contaminants, including chlorinated solvents, in groundwater and soil. Because of the high specific surface area of nZVI particles, this technology achieves treatment rates that are significantly faster than micron-scale and granular ZVI. However, a key technical challenge facing this technology involves agglomeration of nZVI particles. To improve nZVI mobility/deliverability and reactivity, an innovative method was recently developed using a low-cost and bio-degradable organic polymer as a stabilizer. This nZVI stabilization strategy offers unique advantages including: (1) the organic polymer is cost-effective and "green" (completely bio-compatible), (2) the organic polymer is highly effective in stabilizing nZVI particles; and (3) the stabilizer is applied during particle preparation, making nZVI particles more stable. Through a funding from the U.S. Air Force Center for Engineering and the Environment (AFCEE), AMEC performed a field study to test the effectiveness of this innovative technology for degradation of chlorinated solvents in groundwater at a military site. Laboratory treatability tests were conducted using groundwater samples collected from the test site and results indicated that trichloroethene (main groundwater contaminant at the site) was completely degraded within four hours by nZVI particles. In March and May 2011, two rounds of nZVI injection were performed at the test site. Approximately 700 gallons of nZVI suspension with palladium as a catalyst were successfully prepared in the field and injected into the subsurface. Before injection, membrane filters with a pore size of 450 nm were used to check the nZVI particle size and it was observed that >85% of nZVI particles were passed through the filter based on total iron measurement, indicating particle size of <450 nm. During field injections, nZVI particles were observed in a monitoring well located 5 feet downgradient from the injection well. Chlorinated solvent degradation products, e.g. ethane and ethene, increased significantly in monitoring wells following nZVI injections. Groundwater monitoring will be continued for approximately eight months following the last sampling event in July 2011 to demonstrate the performance of nZVI particles.

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)

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.

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.

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.

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

Annual INTEC Groundwater Monitoring Report for Group 5 - Snake River Plain Aquifer (2001)

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

Roddy, Michael Scott

2002-02-01

This report describes the monitoring activities conducted and presents the results of groundwater sampling and water-level measurements from October 2000 to September 2001. Groundwater samples were initially collected from 41 wells from the Idaho Nuclear Technology and Engineering Center and the Central Facilities Area and analyzed for iodine-129, strontium-90, tritium, gross alpha, gross beta, technetium-99, uranium isotopes, plutonium isotopes, neptunium-237, americium-241, gamma spectrometry, and mercury. Samples from 41 wells were collected in April and May 2001. Additional sampling was conducted in August 2001 and included the two CFA production wells, the CFA point of compliance for the production wells, onemore » well that was previously sampled and five additional monitoring wells. Iodine-129 and strontium-90 were the only analytes above their respective maximum contaminant levels. Iodine-129 was detected just above its maximum contaminant level of 1 pCi/L at two of the Central Facilities Area landfill wells. Iodine-129 was detected in the CFA production wells at 0.35±0.083 pCi/L in CFA-1, but was below detectable activity in CFA-2. Strontium-90 was above its maximum contaminant level of 8 pCi/L in several wells near the Idaho Nuclear Technology and Engineering Center but was below its maximum contaminant level in the downgradient wells at the Central Facilities Area landfills. Sr-90 was not detected in the CFA production wells. Gross beta results generally mirrored the results for strontium-90 and technetium-99. Plutonium isotopes and neptunium-237 were not detected. Uranium-233/234 and uranium-238 isotopes were detected in all samples. Concentrations of background and site wells were similar and are within background limits for total uranium determined by the USGS, suggesting that the concentrations are background. Uranium-235/236 was detected in 11 samples, but all the detected concentrations were similar and near the minimum detectable activity. Americium-241 was detected at three locations near the minimum detectable activity of approximately 0.07 pCi/L. The gamma spectrometry results detected cesium-137 in three samples, potassium-40 at eight locations, and radium-226 at one location. Mercury was below its maximum contaminant level of 2 µg/L in all samples. Gamma spectrometry results for the CFA production wells did not detect any analytes. Water-level measurements were taken from wells in the Idaho Nuclear Technology and Engineering Center, Central Facilities Area, and the area south of Central Facilities Area to evaluate groundwater flow directions. Water-level measurements indicated groundwater flow to the south-southwest from the Idaho Nuclear Technology and Engineering Center.« less

Investigating the influence of DNAPL spill characteristics on source zone architecture and mass removal in pool-dominated source zones

NASA Astrophysics Data System (ADS)

Wallace, K. A.; Abriola, L.; Chen, M.; Ramsburg, A.; Pennell, K. D.; Christ, J.

2009-12-01

Multiphase, compositional simulators were employed to investigate the spill characteristics and subsurface properties that lead to pool-dominated, dense non-aqueous phase liquid (DNAPL) source zone architectures. DNAPL pools commonly form at textural interfaces where low permeability lenses restrict the vertical migration of DNAPL, allowing for DNAPL to accumulate, reaching high saturation. Significant pooling has been observed in bench-scale experiments and field settings. However, commonly employed numerical simulations rarely predict the pooling suspected in the field. Given the importance of pooling on the efficacy of mass recovery and the down-gradient contaminant signal, it is important to understand the predominant factors affecting the creation of pool-dominated source zones and their subsequent mass discharge. In this work, contaminant properties, spill characteristics and subsurface permeability were varied to investigate the factors contributing to the development of a pool-dominated source zone. DNAPL infiltration and entrapment simulations were conducted in two- and three-dimensional domains using the University of Texas Chemical Compositional (UTCHEM) simulator. A modified version of MT3DMS was then used to simulate DNAPL dissolution and mass discharge. Numerical mesh size was varied to investigate the importance of numerical model parameters on simulations results. The temporal evolution of commonly employed source zone architecture metrics, such as the maximum DNAPL saturation, first and second spatial moments, and fraction of DNAPL mass located in pools, was monitored to determine how the source zone architecture evolved with time. Mass discharge was monitored to identify the link between source zone architecture and down-gradient contaminant flux. Contaminant characteristics and the presence of extensive low permeability lenses appeared to have the most influence on the development of a pool-dominated source zone. The link between DNAPL mass recovery and contaminant mass discharge was significantly influenced by the fraction of mass residing in DNAPL pools. The greater the fraction of mass residing in DNAPL pools the greater the likelihood for significant reductions in contaminant mass discharge at modest levels of mass removal. These results will help guide numerical and experimental studies on the remediation of pool-dominated source zones and will likely guide future source zone characterization efforts.

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.

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.

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.

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.

Removal of microbial pathogens in a sandy gravel aquifer under forced-gradient subsurface flow conditions

NASA Astrophysics Data System (ADS)

Oudega, Thomas James; Derx, Julia; van Driezum, Inge; Cisneros, Anibal; Sommer, Regina; Kirschner, Alexander; Farnleitner, Andreas; Blaschke, Alfred Paul

2017-04-01

Subsurface media are being used around the world as a means to mitigate microbial contamination, but vary widely in their ability to remove pathogens. To help to provide accurate risk assessments of microbial contamination of groundwaters, and establish safe setback distances between receiving waters and disposal fields, this study aims to use aquifer tracer tests to evaluate the ability of subsurface media to attenuate these pathogens. The novelty of this work is the use of a variety of different tracer substances (e.g. phages, spores, microspheres, conservative tracers) together in field experiments. This will be done by means of injecting these substances under a forced gradient in a sandy gravel aquifer in Lobau, Austria. The extraction of the tracers will be monitored in a pumping well at a distrance of 50m downgradient. This will be able to provide us with insight to the characteristics of microbial transport and how the microorganisms react to the subsurface in the study site. Subsequent numerical modelling of the experiments can tell us more about quantification of subsurface processes such as attachment/detachment, inactivation and die-off of these substances. The first field experiment with conservative tracers (NaCl) has been carried out in December 2016, and subsequent tests are being planned for the next months.

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)

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.

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.

An open-loop ground-water heat pump system: transient numerical modeling and site experimental results

NASA Astrophysics Data System (ADS)

Lo Russo, S.; Taddia, G.; Gnavi, L.

2012-04-01

KEY WORDS: Open-loop ground water heat pump; Feflow; Low-enthalpy; Thermal Affected Zone; Turin; Italy The increasing diffusion of low-enthalpy geothermal open-loop Groundwater Heat Pumps (GWHP) providing buildings air conditioning requires a careful assessment of the overall effects on groundwater system, especially in the urban areas where several plants can be close together and interfere. One of the fundamental aspects in the realization of an open loop low-enthalpy geothermal system is therefore the capacity to forecast the effects of thermal alteration produced in the ground, induced by the geothermal system itself. The impact on the groundwater temperature in the surrounding area of the re-injection well (Thermal Affected Zone - TAZ) is directly linked to the aquifer properties. The transient dynamic of groundwater discharge and temperature variations should be also considered to assess the subsurface environmental effects of the plant. The experimental groundwater heat pump system used in this study is installed at the "Politecnico di Torino" (NW Italy, Piedmont Region). This plant provides summer cooling needs for the university buildings. This system is composed by a pumping well, a downgradient injection well and a control piezometer. The system is constantly monitored by multiparameter probes measuring the dynamic of groundwater temperature. A finite element subsurface flow and transport simulator (FEFLOW) was used to investigate the thermal aquifer alteration. Simulations were continuously performed during May-October 2010 (cooling period). The numerical simulation of the heat transport in the aquifer was solved with transient conditions. The simulation was performed by considering only the heat transfer within the saturated aquifer, without any heat dispersion above or below the saturated zone due to the lack of detailed information regarding the unsaturated zone. Model results were compared with experimental temperature data derived from groundwater monitoring in the surrounding area of the injection well. Such analysis showed that the measured values differ slightly from the simulated values. That small difference is probably due to the simplification assumptions in the modelling. This hypothesis is still under investigation.

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

Evaluation of Long-term Performance of Enhanced Anaerobic Source Zone Bioremediation using mass flux

NASA Astrophysics Data System (ADS)

Haluska, A.; Cho, J.; Hatzinger, P.; Annable, M. D.

2017-12-01

Chlorinated ethene DNAPL source zones in groundwater act as potential long term sources of contamination as they dissolve yielding concentrations well above MCLs, posing an on-going public health risk. Enhanced bioremediation has been applied to treat many source zones with significant promise, but long-term sustainability of this technology has not been thoroughly assessed. This study evaluated the long-term effectiveness of enhanced anaerobic source zone bioremediation at chloroethene contaminated sites to determine if the treatment prevented contaminant rebound and removed NAPL from the source zone. Long-term performance was evaluated based on achieving MCL-based contaminant mass fluxes in parent compound concentrations during different monitoring periods. Groundwater concertation versus time data was compiled for 6-sites and post-remedial contaminant mass flux data was then measured using passive flux meters at wells both within and down-gradient of the source zone. Post-remedial mass flux data was then combined with pre-remedial water quality data to estimate pre-remedial mass flux. This information was used to characterize a DNAPL dissolution source strength function, such as the Power Law Model and the Equilibrium Stream tube model. The six-sites characterized for this study were (1) Former Charleston Air Force Base, Charleston, SC; (2) Dover Air Force Base, Dover, DE; (3) Treasure Island Naval Station, San Francisco, CA; (4) Former Raritan Arsenal, Edison, NJ; (5) Naval Air Station, Jacksonville, FL; and, (6) Former Naval Air Station, Alameda, CA. Contaminant mass fluxes decreased for all the sites by the end of the post-treatment monitoring period and rebound was limited within the source zone. Post remedial source strength function estimates suggest that decreases in contaminant mass flux will continue to occur at these sites, but a mass flux based on MCL levels may never be exceeded. Thus, site clean-up goals should be evaluated as order-of-magnitude reductions. Additionally, sites may require monitoring for a minimum of 5-years in order to sufficiently evaluate remedial performance. The study shows that enhanced anaerobic source zone bioremediation contributed to a modest reduction of source zone contaminant mass discharge and appears to have mitigated rebound of chlorinated ethenes.

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)

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.

Microbial Community Structure of an Alluvial Aquifer Treated to Encourage Microbial Induced Calcite Precipitation

NASA Astrophysics Data System (ADS)

Ohan, J.; Saneiyan, S.; Lee, J.; Ntarlagiannis, D.; Burns, S.; Colwell, F. S.

2017-12-01

An oligotrophic aquifer in the Colorado River floodplain (Rifle, CO) was treated with molasses and urea to encourage microbial induced calcite precipitation (MICP). This would stabilize the soil mass by reducing porosity and strengthening the mineral fabric. Over the course of a 15-day treatment period, microbial biomass was collected from monitoring well groundwater for DNA extraction and sequencing. Bromide, a conservative tracer, was co-injected and subsequently detected in downgradient wells, confirming effective nutrient delivery. Conductivity increased during the injection regime and an overall decrease in pH was observed. Groundwater chemistry showed a marked increase in ammonia, suggesting urea hydrolysis - a process catalyzed by the enzyme urease - the primary enzyme implicated in MICP. Additionally, soluble iron was detected, suggesting a general increase in microbial activity; possibly as iron-reducing bacteria changed insoluble ferric oxide to soluble ferrous hydroxide in the anoxic aquifer. DNA sequencing of the 16S rRNA gene confirmed the presence of iron reducing bacteria, including Shewanella and Desulfuromonadales. Generally, a decrease in microbial community diversity was observed when pre-injection community taxa were compared with post-injection community taxa. Phyla indicative of anoxic aquifers were represented in accordance with previous literature at the Rifle site. Linear discriminant analysis showed significant differences in representative phyla over the course of the injection series. Geophysical monitoring of the site further suggested changes that could be due to MICP. Induced polarization increased the phase shift in the primary treated area, in agreement with laboratory experiments. Cross-hole seismic testing confirmed that the shear wave velocities increased in the treated soil mass, implying the soil matrix became more stable. Future investigations will help elucidate the viability and efficacy of MICP treatment in changing microbial community structure, and the functional attributes associated with community change, so that physical strengthening of soils by microbial action can be accomplished.

Recommendations for new monitoring wells at Everest, Kansas.

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

LaFreniere, L. M.

2007-05-03

On February 15, 2007, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) submitted Recommendations for Remedial Action at Everest, Kansas. Those Recommendations were accepted by the Kansas Department of Health and Environment (KDHE) in a letter to the CCC/USDA dated March 5, 2007. The approved Recommendations document outlines a plan for systematic groundwater sampling and monitoring at Everest to provide data necessary for the critical evaluation of remedial options - including a phytoremediation alternative - for restoration of the groundwater and protection of the surface waters of the intermittent creek at this site. Phase I of themore » KDHE-approved monitoring plan includes the following activities: (1) Groundwater sampling at existing monitoring wells, with analyses for volatile organic compounds (VOCs) and selected biodegradation parameters; (2) Sampling of surface waters along the intermittent creek for VOCs analyses; and (3) Periodic manual measurement and automated recording of groundwater and surface water levels in the vicinity of the intermittent creek. The locations selected for groundwater and surface water sampling and analyses under the approved monitoring program were determined in consultation with the KDHE. As a result of subsequent discussions among representatives of the KDHE, the CCC/USDA, and Argonne regarding the technical program at Everest, the CCC/USDA seeks KDHE approval for the installation of up to four new permanent monitoring wells along the upper reach of the intermittent creek west of the Nigh property, as shown in Figure 1. The proposed new well locations lie progressively downgradient in the anticipated direction of future groundwater and contaminant movement; all of the recommended points lie at least 2,000 ft upgradient, however, of the confirmed area of groundwater discharge to the creek identified near Highway 73. The proposed new wells will supplement the existing network of groundwater and surface water monitoring points identified in the KDHE-approved monitoring plan. The new wells will be sampled in accord with the schedules outlined in the approved plan. The new wells are recommended to address specific investigation needs, as follows: (1) The proposed borings will provide data on the lithologic and hydrogeologic characteristics - and the relative continuity - of the Everest aquifer unit along the upgradient reach of the intermittent creek, where possible implementation of a phytoremediation remedy is under consideration. (2) Installation of the borings will permit the collection of sediments from the aquifer unit for possible physical or hydraulic property analyses. The completed monitoring wells will also facilitate possible future in situ estimation of the aquifer unit's hydraulic properties in this area, as part of the remedy evaluation and development process. (3) The completed new wells will be used to determine the depths to groundwater and the pattern(s) of groundwater flow near the intermittent creek, and hence to predict more accurately the locations of possible groundwater (and contaminant) discharge and the extent of the area amenable to possible phytoremediation. (4) The use of automated groundwater level recorders at the new locations will provide data on the potential range and variability of groundwater levels to be expected in the area near the intermittent creek. (5) Periodic sampling of the recommended wells for VOCs analyses will help to constrain (1) the rate(s) and pathway(s) of contaminant approach toward the intermittent creek (and the area amenable to possible phytoremediation) and (2) the areal extent of the plume as it continues to evolve. The resulting 'early warning' data obtained from this sampling will therefore help to ensure that remedial action can be taken, if necessary, in sufficient time to prevent unacceptable levels of carbon tetrachloride contamination from threatening the identified surface waters of the creek. The well locations shown in Figure 1 were chosen to satisfy the technical objectives above, as well as to minimize disruption (to the extent possible) of the normal agricultural activities in the required investigation area. To accommodate these somewhat conflicting goals, the recommended monitoring points include one new well (PZ1) along the existing waterways west of the Nigh property, one new well (PZ3) along the margin of the farm field southwest of existing well SB63 and northeast of well SB64, and two new wells (PZ2, PZ4) in the fields east of the intermittent creek. The CCC/USDA has contacted the potentially affected landowner and is attempting to negotiate access to the desired well locations. If the necessary access cannot be obtained, a modified distribution of three new monitoring wells, to be located entirely along the existing waterways west and southwest of the Nigh property, is proposed as a possible alternate configuration.« less

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

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.

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

LaFreniere, L. M.

Everest, Kansas, is a small rural community (population approximately 300) located in the southeast corner of Brown County, in the northeastern corner of Kansas. Carbon tetrachloride and chloroform contamination in groundwater at Everest was initially identified in 1997 as a result of testing performed under the Commodity Credit Corporation/U.S. Department of Agriculture (CCC/USDA) private well sampling program conducted by the Kansas Department of Health and Environment (KDHE). The KDHE collected samples from seven private wells in and near Everest. Carbon tetrachloride and chloroform were found in only one of the wells, the Donnie Nigh domestic well (owned at that timemore » by Tim Gale), approximately 3/8 mi northwest of the former Everest CCC/USDA facility. Carbon tetrachloride and chloroform were detected at 121 {mu}g/L and 4 {mu}g/L, respectively. Nitrate was found at 12.62 mg/L. The USDA subsequently connected the Nigh residence to the Everest public water supply system. The findings of the 2011 monitoring at Everest support the following conclusions: (1) Measurements of groundwater levels obtained manually during annual monitoring in 2009-2011 (and through the use of automatic recorders in 2002-2010) have consistently indicated an initial direction of groundwater flow from the former CCC/USDA facility to the north-northwest and toward the Nigh property, 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) At most of the monitored locations, carbon tetrachloride concentrations decreased in April 2011 relative to 2010 results. Noteworthy decreases of > 50% occurred at locations MW4, MW60, and MW88, in the most concentrated part of the plume. (3) Comparison of accumulated data demonstrates that the area of the carbon tetrachloride plume with concentrations > 200 {mu}g/L has decreased markedly over time and suggests a generally decreasing trend in contaminant levels. (4) The trace increases in carbon tetrachloride concentrations observed in 2010 at locations SB63 and SB64 were notable because of the locations proximity to the downgradient intermittent creek. However, these increases were not confirmed in sampling in 2011. (5) The results of the April 2011 monitoring event continue to support the interpretation, made during the 9-yr observation period from 2001 to 2010, that the migration rate for contamination in groundwater toward the intermittent creek is very slow. (6) No carbon tetrachloride was detected in five samples of surface water collected from the intermittent creek west of the former CCC/USDA facility and the Nigh property, or in tree branch tissue samples collected at locations along the banks of the creek. These observations indicate that the carbon tetrachloride contamination identified at Everest has, to date, not impacted the surface waters of the intermittent creek.« less

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

Integration of stable carbon isotope, microbial community, dissolved hydrogen gas, and 2HH2O tracer data to assess bioaugmentation for chlorinated ethene degradation in fractured rocks

USGS Publications Warehouse

Révész, Kinga M.; Lollar, Barbara Sherwood; Kirshtein, Julie D.; Tiedeman, Claire; Imbrigiotta, Thomas E.; Goode, Daniel J.; Shapiro, Allen M.; Voytek, Mary A.; Lancombe, Pierre J.; Busenberg, Eurybiades

2014-01-01

An in situ bioaugmentation (BA) experiment was conducted to understand processes controlling microbial dechlorination of trichloroethene (TCE) in groundwater at the Naval Air Warfare Center (NAWC), West Trenton, NJ. In the BA experiment, an electron donor (emulsified vegetable oil and sodium lactate) and a chloro-respiring microbial consortium were injected into a well in fractured mudstone of Triassic age. Water enriched in 2H was also injected as a tracer of the BA solution, to monitor advective transport processes. The changes in concentration and the δ13C of TCE, cis-dichloroethene (cis-DCE), and vinyl chloride (VC); the δ2H of water; changes in the abundance of the microbial communities; and the concentration of dissolved H2 gas compared to pre- test conditions, provided multiple lines of evidence that enhanced biodegradation occurred in the injection well and in two downgradient wells. For those wells where the biodegradation was stimulated intensively, the sum of the molar chlorinated ethene (CE) concentrations in post-BA water was higher than that of the sum of the pre-BA background molar CE concentrations. The concentration ratios of TCE/(cis-DCE + VC) indicated that the increase in molar CE concentration may result from additional TCE mobilized from the rock matrix in response to the oil injection or due to desorption/diffusion. The stable carbon isotope mass-balance calculations show that the weighted average 13C isotope of the CEs was enriched for around a year compared to the background value in a two year monitoring period, an effective indication that dechlorination of VC was occurring. Insights gained from this study can be applied to efforts to use BA in other fractured rock systems. The study demonstrates that a BA approach can substantially enhance in situ bioremediation not only in fractures connected to the injection well, but also in the rock matrix around the well due to processes such as diffusion and desorption. Because the effect of the BA was intensive only in wells where an amendment was distributed during injection, it is necessary to adequately distribute the amendments throughout the fractured rock to achieve substantial bioremediation. The slowdown in BA effect after a year is due to some extend to the decrease abundant of appropriate microbes, but more likely the decreased concentration of electron donor.

Integration of stable carbon isotope, microbial community, dissolved hydrogen gas, and ²HH₂O tracer data to assess bioaugmentation for chlorinated ethene degradation in fractured rocks.

PubMed

Révész, Kinga M; Lollar, Barbara Sherwood; Kirshtein, Julie D; Tiedeman, Claire R; Imbrigiotta, Thomas E; Goode, Daniel J; Shapiro, Allen M; Voytek, Mary A; Lacombe, Pierre J; Busenberg, Eurybiades

2014-01-01

An in situ bioaugmentation (BA) experiment was conducted to understand processes controlling microbial dechlorination of trichloroethene (TCE) in groundwater at the Naval Air Warfare Center (NAWC), West Trenton, NJ. In the BA experiment, an electron donor (emulsified vegetable oil and sodium lactate) and a chloro-respiring microbial consortium were injected into a well in fractured mudstone of Triassic age. Water enriched in ²H was also injected as a tracer of the BA solution, to monitor advective transport processes. The changes in concentration and the δ¹³C of TCE, cis-dichloroethene (cis-DCE), and vinyl chloride (VC); the δ²H of water; changes in the abundance of the microbial communities; and the concentration of dissolved H₂ gas compared to pre- test conditions, provided multiple lines of evidence that enhanced biodegradation occurred in the injection well and in two downgradient wells. For those wells where the biodegradation was stimulated intensively, the sum of the molar chlorinated ethene (CE) concentrations in post-BA water was higher than that of the sum of the pre-BA background molar CE concentrations. The concentration ratios of TCE/(cis-DCE+VC) indicated that the increase in molar CE concentration may result from additional TCE mobilized from the rock matrix in response to the oil injection or due to desorption/diffusion. The stable carbon isotope mass-balance calculations show that the weighted average ¹³C isotope of the CEs was enriched for around a year compared to the background value in a two year monitoring period, an effective indication that dechlorination of VC was occurring. Insights gained from this study can be applied to efforts to use BA in other fractured rock systems. The study demonstrates that a BA approach can substantially enhance in situ bioremediation not only in fractures connected to the injection well, but also in the rock matrix around the well due to processes such as diffusion and desorption. Because the effect of the BA was intensive only in wells where an amendment was distributed during injection, it is necessary to adequately distribute the amendments throughout the fractured rock to achieve substantial bioremediation. The slowdown in BA effect after a year is due to some extend to the decrease abundant of appropriate microbes, but more likely the decreased concentration of electron donor. © 2013. Published by Elsevier B.V. All rights reserved.

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.

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.

Eddy heat flux across the Antarctic Circumpolar Current estimated from sea surface height standard deviation

NASA Astrophysics Data System (ADS)

Foppert, Annie; Donohue, Kathleen A.; Watts, D. Randolph; Tracey, Karen L.

2017-08-01

Eddy heat flux (EHF) is a predominant mechanism for heat transport across the zonally unbounded mean flow of the Antarctic Circumpolar Current (ACC). Observations of dynamically relevant, divergent, 4 year mean EHF in Drake Passage from the cDrake project, as well as previous studies of atmospheric and oceanic storm tracks, motivates the use of sea surface height (SSH) standard deviation, H*, as a proxy for depth-integrated, downgradient, time-mean EHF (>[EHF>¯>]) in the ACC. Statistics from the Southern Ocean State Estimate corroborate this choice and validate throughout the ACC the spatial agreement between H* and >[EHF>¯>] seen locally in Drake Passage. Eight regions of elevated >[EHF>¯>] are identified from nearly 23.5 years of satellite altimetry data. Elevated cross-front exchange usually does not span the full latitudinal width of the ACC in each region, implying a hand-off of heat between ACC fronts and frontal zones as they encounter the different >[EHF>¯>] hot spots along their circumpolar path. Integrated along circumpolar streamlines, defined by mean SSH contours, there is a convergence of ∮>[EHF>¯>] in the ACC: 1.06 PW enters from the north and 0.02 PW exits to the south. Temporal trends in low-frequency [EHF] are calculated in a running-mean sense using H* from overlapping 4 year subsets of SSH. Significant increases in downgradient [EHF] magnitude have occurred since 1993 at Kerguelen Plateau, Southeast Indian Ridge, and the Brazil-Malvinas Confluence, whereas the other five >[EHF>¯>] hot spots have insignificant trends of varying sign.

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.

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)

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.

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.

Investigation of Contaminated Groundwater at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina, 2008

USGS Publications Warehouse

Vroblesky, Don A.; Petkewich, Matthew D.

2009-01-01

The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated natural and engineered remediation of chlorinated volatile organic compound (VOC) groundwater 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. Engineered remediation aspects at the site consist of a zero-valent-iron permeable reactive barrier (PRB) installed in December 2002 intercepting the contamination plume and a phytoremediation test stand of loblolly pine trees planted in the source area in May 2003. The U.S. Geological Survey planted an additional phytoremediation test stand of loblolly pine trees on the upgradient side of the southern end of the PRB in February 2008. At least once during the summer, however, the trees were inadvertently mowed during lawn cutting activity. The 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 upgradient from the PRB showed a general decrease in VOC concentrations. VOC concentrations in some wells in the forest downgradient from the PRB showed a sharp increase in 2005, followed by a decrease in 2006. Farther downgradient in the forest, the VOC concentrations began to increase in 2007 and continued to increase into 2008. The VOC-concentration changes in groundwater beneath the forest appear to indicate movement of a groundwater-contaminant pulse through the forest. It also is possible that the data may represent lateral shifting of the plume in response to changes in groundwater-flow direction.

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.

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...

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.

Analysis of single-hole and cross-hole tracer tests conducted at the Nye County early warning drilling program well complex, Nye County, Nevada

USGS Publications Warehouse

Umari, A.; Earle, J.D.; Fahy, M.F.

2006-01-01

As part of the effort to understand the flow and transport characteristics downgradient from the proposed high-level radioactive waste geologic repository at Yucca Mountain, Nevada, single- and cross-hole tracer tests were conducted from December 2004 through October 2005 in boreholes at the Nye County 22 well complex. The results were analyzed for transport properties using both numerical and analytical solutions of the governing advection dispersion equation. Preliminary results indicate effective flow porosity values ranging from 1.0 ?? 10-2 for an individual flow path to 2.0 ?? 10 -1 for composite flow paths, longitudinal dispersivity ranging from 0.3 to 3 m, and a transverse horizontal dispersivity of 0.03 m. Individual flow paths identified from the cross-hole testing indicate some solute diffusion into the stagnant portion of the alluvial aquifer.

Meta-Modeling-Based Groundwater Remediation Optimization under Flexibility in Environmental Standard.

PubMed

He, Li; Xu, Zongda; Fan, Xing; Li, Jing; Lu, Hongwei

2017-05-01

  This study develops a meta-modeling based mathematical programming approach with flexibility in environmental standards. It integrates numerical simulation, meta-modeling analysis, and fuzzy programming within a general framework. A set of models between remediation strategies and remediation performance can well guarantee the mitigation in computational efforts in the simulation and optimization process. In order to prevent the occurrence of over-optimistic and pessimistic optimization strategies, a high satisfaction level resulting from the implementation of a flexible standard can indicate the degree to which the environmental standard is satisfied. The proposed approach is applied to a naphthalene-contaminated site in China. Results show that a longer remediation period corresponds to a lower total pumping rate and a stringent risk standard implies a high total pumping rate. The wells located near or in the down-gradient direction to the contaminant sources have the most significant efficiency among all of remediation schemes.

Geophysical logging and thermal imaging near the Hemphill Road TCE National Priorities List Superfund site near Gastonia, North Carolina

USGS Publications Warehouse

Antolino, Dominick J.; Chapman, Melinda J.

2017-03-27

Borehole geophysical logs and thermal imaging data were collected by the U.S. Geological Survey near the Hemphill Road TCE (trichloroethylene) National Priorities List Superfund site near Gastonia, North Carolina, during August 2014 through February 2015. In an effort to assist the U.S. Environmental Protection Agency in the development of a conceptual groundwater model for the assessment of current contaminant distribution and future migration of contaminants, surface geological mapping and borehole geophysical log and thermal imaging data collection, which included the delineation of more than 600 subsurface features (primarily fracture orientations), was completed in five open borehole wells and two private supply bedrock wells. In addition, areas of possible groundwater discharge within a nearby creek downgradient of the study site were determined based on temperature differences between the stream and bank seepage using thermal imagery.

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

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.

Rebound of a coal tar creosote plume following partial source zone treatment with permanganate.

PubMed

Thomson, N R; Fraser, M J; Lamarche, C; Barker, J F; Forsey, S P

2008-11-14

The long-term management of dissolved plumes originating from a coal tar creosote source is a technical challenge. For some sites stabilization of the source may be the best practical solution to decrease the contaminant mass loading to the plume and associated off-site migration. At the bench-scale, the deposition of manganese oxides, a permanganate reaction byproduct, has been shown to cause pore plugging and the formation of a manganese oxide layer adjacent to the non-aqueous phase liquid creosote which reduces post-treatment mass transfer and hence mass loading from the source. The objective of this study was to investigate the potential of partial permanganate treatment to reduce the ability of a coal tar creosote source zone to generate a multi-component plume at the pilot-scale over both the short-term (weeks to months) and the long-term (years) at a site where there is >10 years of comprehensive synoptic plume baseline data available. A series of preliminary bench-scale experiments were conducted to support this pilot-scale investigation. The results from the bench-scale experiments indicated that if sufficient mass removal of the reactive compounds is achieved then the effective solubility, aqueous concentration and rate of mass removal of the more abundant non-reactive coal tar creosote compounds such as biphenyl and dibenzofuran can be increased. Manganese oxide formation and deposition caused an order-of-magnitude decrease in hydraulic conductivity. Approximately 125 kg of permanganate were delivered into the pilot-scale source zone over 35 days, and based on mass balance estimates <10% of the initial reactive coal tar creosote mass in the source zone was oxidized. Mass discharge estimated at a down-gradient fence line indicated >35% reduction for all monitored compounds except for biphenyl, dibenzofuran and fluoranthene 150 days after treatment, which is consistent with the bench-scale experimental results. Pre- and post-treatment soil core data indicated a highly variable and random spatial distribution of mass within the source zone and provided no insight into the mass removed of any of the monitored species. The down-gradient plume was monitored approximately 1, 2 and 4 years following treatment. The data collected at 1 and 2 years post-treatment showed a decrease in mass discharge (10 to 60%) and/or total plume mass (0 to 55%); however, by 4 years post-treatment there was a rebound in both mass discharge and total plume mass for all monitored compounds to pre-treatment values or higher. The variability of the data collected was too large to resolve subtle changes in plume morphology, particularly near the source zone, that would provide insight into the impact of the formation and deposition of manganese oxides that occurred during treatment on mass transfer and/or flow by-passing. Overall, the results from this pilot-scale investigation indicate that there was a significant but short-term (months) reduction of mass emanating from the source zone as a result of permanganate treatment but there was no long-term (years) impact on the ability of this coal tar creosote source zone to generate a multi-component plume.

Bioremediation in fractured rock: 1. Modeling to inform design, monitoring, and expectations

USGS Publications Warehouse

Tiedeman, Claire; Shapiro, Allen M.; Hsieh, Paul A.; Imbrigiotta, Thomas; Goode, Daniel J.; Lacombe, Pierre; DeFlaun, Mary F.; Drew, Scott R.; Johnson, Carole D.; Williams, John H.; Curtis, Gary P.

2018-01-01

Field characterization of a trichloroethene (TCE) source area in fractured mudstones produced a detailed understanding of the geology, contaminant distribution in fractures and the rock matrix, and hydraulic and transport properties. Groundwater flow and chemical transport modeling that synthesized the field characterization information proved critical for designing bioremediation of the source area. The planned bioremediation involved injecting emulsified vegetable oil and bacteria to enhance the naturally occurring biodegradation of TCE. The flow and transport modeling showed that injection will spread amendments widely over a zone of lower‐permeability fractures, with long residence times expected because of small velocities after injection and sorption of emulsified vegetable oil onto solids. Amendments transported out of this zone will be diluted by groundwater flux from other areas, limiting bioremediation effectiveness downgradient. At nearby pumping wells, further dilution is expected to make bioremediation effects undetectable in the pumped water. The results emphasize that in fracture‐dominated flow regimes, the extent of injected amendments cannot be conceptualized using simple homogeneous models of groundwater flow commonly adopted to design injections in unconsolidated porous media (e.g., radial diverging or dipole flow regimes). Instead, it is important to synthesize site characterization information using a groundwater flow model that includes discrete features representing high‐ and low‐permeability fractures. This type of model accounts for the highly heterogeneous hydraulic conductivity and groundwater fluxes in fractured‐rock aquifers, and facilitates designing injection strategies that target specific volumes of the aquifer and maximize the distribution of amendments over these volumes.

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

A unified view of convective transports by stratocumulus clouds, shallow cumulus clouds, and deep convection

NASA Technical Reports Server (NTRS)

Randall, David A.

1990-01-01

A bulk planetary boundary layer (PBL) model was developed with a simple internal vertical structure and a simple second-order closure, designed for use as a PBL parameterization in a large-scale model. The model allows the mean fields to vary with height within the PBL, and so must address the vertical profiles of the turbulent fluxes, going beyond the usual mixed-layer assumption that the fluxes of conservative variables are linear with height. This is accomplished using the same convective mass flux approach that has also been used in cumulus parameterizations. The purpose is to show that such a mass flux model can include, in a single framework, the compensating subsidence concept, downgradient mixing, and well-mixed layers.

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.

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...

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...

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 ...

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.

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

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.

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.

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.

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.

A method for designing configurations of nested monitoring wells near landfills

NASA Astrophysics Data System (ADS)

Hudak, Paul F.

A method was devised for designing configurations of monitoring wells, consisting of vertically nested intakes in boreholes. The network-design method involves analyzing a subset of potential contaminant plumes emerging from the downgradient margin of a landfill. Plume widths are evaluated along selected equipotential lines and compared to the lengths of those lines. The method was applied to a 32-ha solid-waste landfill in Tarrant County, Texas, USA. Sixtynine potential source nodes were considered. A 15-borehole network devised by the method registered 93 detections in total, detecting all 69 model-generated plumes by at least one borehole. Based on an enumeration procedure, a minimum of 10 boreholes was needed to detect all of the model-generated plumes. However, the less conservative 10-borehole network had little capability for backup detection. An existing monitoring network of seven downgradient wells detected only 38 model-generated plumes. Results of this study illustrate a practical need for structured approaches to designing detection-based groundwater-monitoring configurations. Résumé Une méthode a été développée pour fournir les caractéristiques de puits de surveillance, avec des points de prélèvements superposés en forage. La méthode de réalisation du réseau s'appuie sur l'analyse d'un ensemble de panaches de pollution potentiels provenant du bord en aval d'une décharge. Les largeurs de panache sont estimées le long d'isopièzes sélectionnées et sont comparées à leur longueur. Cette méthode a été appliquée à une décharge de déchets solides couvrant 32ha, dans le canton de Tarrant (Texas, Etats-Unis). 69 noeuds de source potentielle de pollution ont été pris en compte. Un réseau de 15 forages, défini par la méthode, a enregistré au total 93 alarmes, détectant les 69 panaches simulés dans au moins un forage. Une procédure de dénombrement précise qu'un minimum de 10 forages est nécessaire pour détecter tous les panaches simulés par le modèle. Cependant, le réseau minimal de 10 forages offre une faible aptitude de détection. Un réseau existant de contrôle de 7 puits situés en aval ne détectent que 38 panaches simulés par le modèle. Les résultats de cette étude illustrent la nécessité pratique d'approches structurées pour la définition des caractéristiques de surveillance d'une nappe basée sur la détection. Resumen Se ha puesto en marcha un método para diseñar la configuración de los pozos de observación, que consiste en estudiar las captaciones en tramos anidados verticalmente. El método de diseño de redes incluye el análisis de un subconjunto de penachos de contaminación que emergen potencialmente aguas abajo de un vertedero. Se evalúa la anchura de los penachos a lo largo de líneas equipotenciales seleccionadas y se compara con la longitud de estas líneas. El método se aplicó a un vertedero de sustancias sólidas con una extensión de 32 hectáreas en Tarrant County, Texas, EEUU. Se consideraron 69 fuentes de contaminación potencial. Una red de 15 sondeos, seleccionada mediante el nuevo método, registró un total de 93 detecciones, consiguiendo detectar el total de los 69 penachos generados en por lo menos un pozo. Basándose en un procedimiento de enumeración, se vio se requería un mínimo de 10 sondeos para registrar la totalidad de los penachos. Sin embargo, esta red de 10 sondeos se considera muy poco conservativa, ya que tenía una capacidad limitada para detectar los puntos de partida. Una red ya existente, formada por siete pozos aguas abajo de la zona de vertido, detectó sólo 38 de los penachos. Los resultados de este estudio ilustran la necesidad práctica de metodologías estructuradas para diseñar las configuraciones de redes de observación.

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

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.

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.

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)

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 ...

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 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.

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.

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

LaFreniere, L. M.; Environmental Science Division

In September 2005, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) initiated periodic sampling of groundwater in the vicinity of a grain storage facility formerly operated by the CCC/USDA at Morrill, Kansas. The sampling at Morrill is being performed on behalf of the CCC/USDA by Argonne National Laboratory, in accord with a monitoring program approved by the Kansas Department of Health and Environment (KDHE 2005), to monitor levels of carbon tetrachloride contamination identified in the groundwater at this site (Argonne 2004, 2005a). This report provides results for monitoring events in April and September 2009. Under the KDHE-approvedmore » monitoring plan (Argonne 2005b), groundwater was initially sampled twice yearly for a period of two years (in fall 2005, in spring and fall 2006, and in spring and fall 2007). The samples were analyzed for volatile organic compounds (VOCs), as well as for selected geochemical parameters to aid in the evaluation of possible natural contaminant degradation (reductive dechlorination) processes in the subsurface environment. The analytical results for groundwater sampling events at Morrill from September 2005 to October 2008 were documented previously (Argonne 2006a,b, 2007, 2008a,b, 2009). Those results consistently demonstrated the presence of carbon tetrachloride contamination, at levels exceeding the KDHE Tier 2 risk-based screening level of 5.0 {micro}g/L for this compound, in a groundwater plume extending generally south-southeastward from the former CCC/USDA facility, toward Terrapin Creek at the south edge of the town. Low levels ({le} 1.3 {micro}g/L) of carbon tetrachloride were persistently detected at monitoring well MW8S, on the bank of an intermittent tributary to Terrapin Creek. This observation suggested a possible risk of contamination of the surface waters of the creek. That concern is the regulatory driver for ongoing monitoring. In light of the early findings, in 2006 the CCC/USDA recommended expansion of the approved monitoring program to include the collection and analysis of surface water samples along Terrapin Creek (Argonne 2006a). At the request of the KDHE (2007a), locations for both surface water and shallow sediment sampling were discussed with the KDHE in January 2007. An addendum to the existing monitoring plan (Appendix A) and a standard operating procedure (SOP AGEM-15; Appendix B) for sediment sampling were submitted to the KDHE on the basis of these discussions and were subsequently approved (KDHE 2008b). Results of sediment sampling prior to 2009 were reported previously (Argonne 2008a,b; 2009). To supplement the original scope of the monitoring, Argonne also sampled natural vegetation along Terrapin Creek in October 2006, April 2007, and July 2007 for analyses for VOCs. The results of these plant tissue analyses were reported previously (Argonne 2008a, 2009). The April and September 2009 sampling events reported here represent a continuation of the two-year monitoring program, as requested by the KDHE (2007b). The groundwater sampling is presently conducted, in accord with the monitoring plan (Argonne 2005b) and the addendum to that plan (Appendix A in this report), in a network of 12 monitoring wells and 3 private wells (Figure 1.1), at locations approved by the KDHE (2008b). The findings of the April and September 2009 monitoring events at Morrill support the following conclusions: (1) Groundwater flow during the early spring and the later part of this review period was predominantly to the south-southeast, from the vicinity of the former CCC/USDA facility toward Terrapin Creek. In late spring, a slight shift occurred toward more southerly groundwater flow (possibly southwesterly in the immediate vicinity of the intermittent tributary that flows into Terrapin Creek). This shift in the late spring reflected transient seasonal precipitation and recharge that resulted in higher groundwater levels at this time. (2) No significant changes were observed in the levels or distribution of carbon tetrachloride in the groundwater at Morrill during the current review period, or in comparison to the results of the spring and fall 2008 monitoring events. A maximum carbon tetrachloride concentration of 28-30 {micro}g/L was identified in groundwater - at well MW3S - during both the April and September 2009 sampling events. (3) No carbon tetrachloride contamination was detected in surface waters or shallow streambed sediments sampled at five locations along Terrapin Creek, downgradient from the former CCC/USDA facility. (4) Sampling of tree branch tissues from existing trees for VOCs analyses can be an indicator of shallow subsurface groundwater contamination. Detections of carbon tetrachloride in vegetation at the Morrill site to date have been generally consistent with the documented location of the groundwater plume.« less

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.

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.

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

Large-scale natural gradient tracer test in sand and gravel, Cape Cod, Massachusetts: 1. Experimental design and observed tracer movement

USGS Publications Warehouse

LeBlanc, Denis R.; Garabedian, Stephen P.; Hess, Kathryn M.; Gelhar, Lynn W.; Quadri, Richard D.; Stollenwerk, Kenneth G.; Wood, Warren W.

1991-01-01

A large-scale natural gradient tracer experiment was conducted on Cape Cod, Massachusetts, to examine the transport and dispersion of solutes in a sand and gravel aquifer. The nonreactive tracer, bromide, and the reactive tracers, lithium and molybdate, were injected as a pulse in July 1985 and monitored in three dimensions as they moved as far as 280 m down-gradient through an array of multilevel samplers. The bromide cloud moved horizontally at a rate of 0.42 m per day. It also moved downward about 4 m because of density-induced sinking early in the test and accretion of areal recharge from precipitation. After 200 m of transport, the bromide cloud had spread more than 80 m in the direction of flow, but was only 14 m wide and 4–6 m thick. The lithium and molybdate clouds followed the same path as the bromide cloud, but their rates of movement were retarded about 50% relative to bromide movement because of sorption onto the sediments.

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.

Arsenic cycling in hydrocarbon plumes: secondary effects of natural attenuation

USGS Publications Warehouse

Cozzarelli, Isabelle M.; Schreiber, Madeline E.; Erickson, Melinda L.; Ziegler, Brady A.

2016-01-01

Monitored natural attenuation is widely applied as a remediation strategy at hydrocarbon spill sites. Natural attenuation relies on biodegradation of hydrocarbons coupled with reduction of electron acceptors, including solid phase ferric iron (Fe(III)). Because arsenic (As) adsorbs to Fe-hydroxides, a potential secondary effect of natural attenuation of hydrocarbons coupled with Fe(III) reduction is a release of naturally occurring As to groundwater. At a crude-oil-contaminated aquifer near Bemidji, Minnesota, anaerobic biodegradation of hydrocarbons coupled to Fe(III) reduction has been well documented. We collected groundwater samples at the site annually from 2009 to 2013 to examine if As is released to groundwater and, if so, to document relationships between As and Fe inside and outside of the dissolved hydrocarbon plume. Arsenic concentrations in groundwater in the plume reached 230 µg/L, whereas groundwater outside the plume contained less than 5 µg/L As. Combined with previous data from the Bemidji site, our results suggest that (1) naturally occurring As is associated with Fe-hydroxides present in the glacially derived aquifer sediments; (2) introduction of hydrocarbons results in reduction of Fe-hydroxides, releasing As and Fe to groundwater; (3) at the leading edge of the plume, As and Fe are removed from groundwater and retained on sediments; and (4) downgradient from the plume, patterns of As and Fe in groundwater are similar to background. We develop a conceptual model of secondary As release due to natural attenuation of hydrocarbons that can be applied to other sites where an influx of biodegradable organic carbon promotes Fe(III) reduction.

Arsenic Cycling in Hydrocarbon Plumes: Secondary Effects of Natural Attenuation.

PubMed

Cozzarelli, Isabelle M; Schreiber, Madeline E; Erickson, Melinda L; Ziegler, Brady A

2016-01-01

Monitored natural attenuation is widely applied as a remediation strategy at hydrocarbon spill sites. Natural attenuation relies on biodegradation of hydrocarbons coupled with reduction of electron acceptors, including solid phase ferric iron (Fe(III)). Because arsenic (As) adsorbs to Fe-hydroxides, a potential secondary effect of natural attenuation of hydrocarbons coupled with Fe(III) reduction is a release of naturally occurring As to groundwater. At a crude-oil-contaminated aquifer near Bemidji, Minnesota, anaerobic biodegradation of hydrocarbons coupled to Fe(III) reduction has been well documented. We collected groundwater samples at the site annually from 2009 to 2013 to examine if As is released to groundwater and, if so, to document relationships between As and Fe inside and outside of the dissolved hydrocarbon plume. Arsenic concentrations in groundwater in the plume reached 230 µg/L, whereas groundwater outside the plume contained less than 5 µg/L As. Combined with previous data from the Bemidji site, our results suggest that (1) naturally occurring As is associated with Fe-hydroxides present in the glacially derived aquifer sediments; (2) introduction of hydrocarbons results in reduction of Fe-hydroxides, releasing As and Fe to groundwater; (3) at the leading edge of the plume, As and Fe are removed from groundwater and retained on sediments; and (4) downgradient from the plume, patterns of As and Fe in groundwater are similar to background. We develop a conceptual model of secondary As release due to natural attenuation of hydrocarbons that can be applied to other sites where an influx of biodegradable organic carbon promotes Fe(III) reduction. © 2015, National Ground Water Association.

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

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.

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.

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.

Concurrent bioremediation of perchlorate and 1,1,1-trichloroethane in an emulsified oil barrier

NASA Astrophysics Data System (ADS)

Borden, Robert C.

2007-10-01

A detailed field pilot test was conducted to evaluate the use of edible oil emulsions for enhanced in situ biodegradation of perchlorate and chlorinated solvents in groundwater. Edible oil substrate (EOS®) was injected into a line of ten direct push injection wells over a 2-day period to form a 15-m-long biologically active permeable reactive barrier (bio-barrier). Field monitoring results over a 2.5-year period indicate the oil injection generated strongly reducing conditions in the oil-treated zone with depletion of dissolved oxygen, nitrate, and sulfate, and increases in dissolved iron, manganese and methane. Perchlorate was degraded from 3100 to 20,000 μg/L to below detection (< 4 μg/L) in the injection and nearby monitor wells within 5 days following the injection. Two years after the single emulsion injection, perchlorate was less than 6 μg/L in every downgradient well compared to an average upgradient concentration of 13,100 μg/L. Immediately after emulsion injection, there were large shifts in concentrations of chlorinated solvents and degradation products due to injection of clean water, sorption to the oil and adaptation of the in situ microbial community. Approximately 4 months after emulsion injection, concentrations of 1,1,1-trichloroethane (TCA), perchloroethene (PCE), trichloroethene (TCE) and their degradation products appeared to reach a quasi steady-state condition. During the period from 4 to 18 months, TCA was reduced from 30-70 μM to 0.2-4 μM during passage through the bio-barrier. However, 1-9 μM 1,1-dichloroethane (DCA) and 8-14 μM of chloroethane (CA) remained indicating significant amounts of incompletely degraded TCA were discharging from the oil-treated zone. During this same period, PCE and TCE were reduced with concurrent production of 1,2- cis-dichloroethene ( cis-DCE). However, very little VC or ethene was produced indicating reductive dechlorination slowed or stopped at cis-DCE. The incomplete removal of TCA, PCE and TCE is likely associated with the short (5-20 days) hydraulic retention time of contaminants in the oil-treated zone. The permeability of the injection wells declined by 39-91% (average = 68%) presumably due to biomass growth and/or gas production. However, non-reactive tracer tests and detailed monitoring of the perchlorate plume demonstrated that the permeability loss did not result in excessive flow bypassing around the bio-barrier. Contaminant transport and degradation within the bio-barrier was simulated using an advection-dispersion-reaction model where biodegradation rate was assumed to be linearly proportional to the residual oil concentration ( Soil) and the contaminant concentration. Using this approach, the calibrated model was able to closely match the observed contaminant distribution. The calibrated model was then used to design a full-scale barrier to treat both ClO 4 and chlorinated solvents.

Concurrent bioremediation of perchlorate and 1,1,1-trichloroethane in an emulsified oil barrier.

PubMed

Borden, Robert C

2007-10-30

A detailed field pilot test was conducted to evaluate the use of edible oil emulsions for enhanced in situ biodegradation of perchlorate and chlorinated solvents in groundwater. Edible oil substrate (EOS) was injected into a line of ten direct push injection wells over a 2-day period to form a 15-m-long biologically active permeable reactive barrier (bio-barrier). Field monitoring results over a 2.5-year period indicate the oil injection generated strongly reducing conditions in the oil-treated zone with depletion of dissolved oxygen, nitrate, and sulfate, and increases in dissolved iron, manganese and methane. Perchlorate was degraded from 3100 to 20,000 microg/L to below detection (<4 microg/L) in the injection and nearby monitor wells within 5 days following the injection. Two years after the single emulsion injection, perchlorate was less than 6 microg/L in every downgradient well compared to an average upgradient concentration of 13,100 microg/L. Immediately after emulsion injection, there were large shifts in concentrations of chlorinated solvents and degradation products due to injection of clean water, sorption to the oil and adaptation of the in situ microbial community. Approximately 4 months after emulsion injection, concentrations of 1,1,1-trichloroethane (TCA), perchloroethene (PCE), trichloroethene (TCE) and their degradation products appeared to reach a quasi steady-state condition. During the period from 4 to 18 months, TCA was reduced from 30-70 microM to 0.2-4 microM during passage through the bio-barrier. However, 1-9 microM 1,1-dichloroethane (DCA) and 8-14 microM of chloroethane (CA) remained indicating significant amounts of incompletely degraded TCA were discharging from the oil-treated zone. During this same period, PCE and TCE were reduced with concurrent production of 1,2-cis-dichloroethene (cis-DCE). However, very little VC or ethene was produced indicating reductive dechlorination slowed or stopped at cis-DCE. The incomplete removal of TCA, PCE and TCE is likely associated with the short (5-20 days) hydraulic retention time of contaminants in the oil-treated zone. The permeability of the injection wells declined by 39-91% (average=68%) presumably due to biomass growth and/or gas production. However, non-reactive tracer tests and detailed monitoring of the perchlorate plume demonstrated that the permeability loss did not result in excessive flow bypassing around the bio-barrier. Contaminant transport and degradation within the bio-barrier was simulated using an advection-dispersion-reaction model where biodegradation rate was assumed to be linearly proportional to the residual oil concentration (Soil) and the contaminant concentration. Using this approach, the calibrated model was able to closely match the observed contaminant distribution. The calibrated model was then used to design a full-scale barrier to treat both ClO4 and chlorinated solvents.

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.

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...

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.

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

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

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.

Geochemical processes in a calcareous sandstone aquifer during managed aquifer recharge with desalinated seawater

NASA Astrophysics Data System (ADS)

Ganot, Yonatan; Russak, Amos; Siebner, Hagar; Bernstein, Anat; Katz, Yoram; Guttman, Jospeh; Kurtzman, Daniel

2017-04-01

In the last three years we monitor Managed Aquifer Recharge (MAR) of post-treated desalinated seawater (PTDES) in an infiltration pond, at the Menashe site that overlies the northern part of the Israeli Coastal Aquifer. The PTDES are stabilized with CaCO3 during post-treatment in the desalination plant and their chemical composition differs from those of any other water recharged to the aquifer and of the natural groundwater. We use suction cups in the unsaturated zone, shallow observation wells within the pond and production wells that encircles the MAR Menashe site, to study the geochemical processes during MAR with PTDES. Ion-enrichment (remineralization) of the recharged water was observed in both unsaturated zone and shallow observation wells samples. Enrichment occurs mainly in the first few meters below the pond surface by ion-exchange processes. Mg2+ enrichment is most prominent due to its deficiency in the PTDES. It is explained by ion-exchange with Ca2+, as the PTDES (enriched with Ca2+) infiltrates through a calcareous-sandstone aquifer with various amount of adsorbed Mg2+ (3-27 meq/kg). Hence, the higher concentration of Ca+2 in the PTDES together with its higher affinity to the sediments promotes the release of Mg2+ ions to the recharged water. Water isotopes analysis of the production wells were used to estimate residence time and mixing with local groundwater. At the end of 2016, it was found that the percentage of PTDES in adjacent down-gradient production wells was around 10%, while more distant or up-gradient wells show no mixing with PTDES. The distinct isotope contrast between the recharged desalinated seawater (δ2H=+11.2±0.2‰) and the local groundwater (δ2H ranged from -22.7 to -16.7‰) is a promising tool to evaluate future mixing processes at the Menshae MAR site. Using the Menashe MAR system for remineralization could be beneficial as a primary or complementary post-treatment technique. However, the sustainability of this process is still questionable, as the recharged water remineralization is accompanied by mineral depletion of the pond sediments. Study on the feasibility of this remineralization scheme is currently ongoing using laboratory column experiments and reactive transport modelling.

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

Long-term ground penetrating radar monitoring of a small volume DNAPL release in a natural groundwater flow field.

PubMed

Hwang, Yong Keun; Endres, Anthony L; Piggott, Scott D; Parker, Beth L

2008-04-04

An earlier field experiment at Canadian Forces Base Borden by Brewster and Annan [Geophysics 59 (1994) 1211] clearly demonstrated the capability of ground penetrating radar (GPR) reflection profiling to detect and monitor the formation of DNAPL layers in the subsurface. Their experiment involved a large volume release (770 L) of tetrachloroethylene into a portion of the sand aquifer that was hydraulically isolated from groundwater flow by sheet pile walls. In this study, we evaluated the ability of GPR profiling to detect and monitor much smaller volume releases (50 L). No subsurface confining structure was used in this experiment; hence, the DNAPL impacted zone was subjected to the natural groundwater flow regime. This condition allowed us to geophysically monitor the DNAPL mass loss over a 66 month period. Reflectivity variations on the GPR profiles were used to infer the presence and evolution of the solvent layers. GPR imaging found significant reflectivity increases due to solvent layer formation during the two week period immediately after the release. These results demonstrated the capacity of GPR profiling for the detection and monitoring of lesser volume DNAPL releases that are more representative of small-scale industrial spills. The GPR imaged solvent layers subsequently reduced in both areal extent and reflectivity after 29 months and almost completely disappeared by the end of the 66 month monitoring period. Total DNAPL mass estimates based on GPR profiling data indicated that the solvent mass was reduced to 34%-36% of its maximum value after 29 months; only 4%-9% of the solvent mass remained in the study area after 66 months. These results are consistent with independent hydrogeological estimates of remaining DNAPL mass based on the downgradient monitoring of the dissolved solvent phase. Hence, we have concluded that the long-term GPR reflectivity changes of the DNAPL layers are likely the result from the dissolution of chlorinated solvents residing in those layers. The long-term monitoring results demonstrated that GPR profiling is a promising non-invasive method for use at DNAPL contaminated sites in sandy aquifers where temporal information about immiscible contaminant mass depletion due to either natural flow or remediation is needed. However, our results also indicated that the GPR signature of older DNAPL impacted zones may not differ greatly from the uncontaminated background if significant mass reduction due to dissolution has occurred.

Fate of sulfamethoxazole, 4-nonylphenol, and 17β-estradiol in groundwater contaminated by wastewater treatment plant effluent

USGS Publications Warehouse

Barber, Larry B.; Keefe, Steffanie H.; LeBlanc, Denis R.; Bradley, Paul M.; Chapelle, Francis H.; Meyer, Michael T.; Loftin, Keith A.; Koplin, Dana W.; Rubio, Fernando

2009-01-01

Organic wastewater contaminants (OWCs) were measured in samples collected from monitoring wells located along a 4.5-km transect of a plume of groundwater contaminated by 60 years of continuous rapid infiltration disposal of wastewater treatment plant effluent. Fifteen percent of the 212 OWCs analyzed were detected, including the antibiotic sulfamethoxazole (SX), the nonionic surfactant degradation product 4-nonylphenol (NP), the solvent tetrachloroethene (PCE), and the disinfectant 1,4-dichlorobenzene (DCB). Comparison of the 2005 sampling results to data collected from the same wells in 1985 indicates that PCE and DCB are transported more rapidly in the aquifer than NP, consistent with predictions based on compound hydrophobicity. Natural gradient in situ tracer experiments were conducted to evaluate the subsurface behavior of SX, NP, and the female sex hormone 17β-estradiol (E2) in two oxic zones in the aquifer: (1) a downgradient transition zone at the interface between the contamination plume and the overlying uncontaminated groundwater and (2) a contaminated zone located beneath the infiltration beds, which have not been loaded for 10 years. In both zones, breakthrough curves for the conservative tracer bromide (Br−) and SX were nearly coincident, whereas NP and E2 were retarded relative to Br− and showed mass loss. Retardation was greater in the contaminated zone than in the transition zone. Attenuation of NP and E2 in the aquifer was attributed to biotransformation, and oxic laboratory microcosm experiments using sediments from the transition and contaminated zones show that uniform-ring-labeled 14C 4-normal-NP was biodegraded more rapidly (30−60% recovered as 14CO2 in 13 days) than 4-14C E2 (20−90% recovered as 14CO2in 54 days). There was little difference in mineralization potential between sites.

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.

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.

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.

Strontium isotope detection of brine contamination in the East Poplar oil field, Montana

USGS Publications Warehouse

Peterman, Zell E.; Thamke, Joanna N.; Futa, Kiyoto; Oliver, Thomas A.

2010-01-01

Brine contamination of groundwater in the East Poplar oil field was first documented in the mid-1980s by the U.S. Geological Survey by using hydrochemistry, with an emphasis on chloride (Cl) and total dissolved solids concentrations. Supply wells for the City of Poplar are located downgradient from the oil field, are completed in the same shallow aquifers that are documented as contaminated, and therefore are potentially at risk of being contaminated. In cooperation with the Office of Environmental Protection of the Fort Peck Tribes, groundwater samples were collected in 2009 and 2010 from supply wells, monitor wells, and the Poplar River for analyses of major and trace elements, including strontium (Sr) concentrations and isotopic compositions. The ratio of strontium-87 to strontium-86 (87Sr/86Sr) is used extensively as a natural tracer in groundwater to detect mixing among waters from different sources and to study the effects of water/rock interaction. On a plot of the reciprocal strontium concentration against the 87Sr/86Sr ratio, mixtures of two end members will produce a linear array. Using this plotting method, data for samples from most of the wells, including the City of Poplar wells, define an array with reciprocal strontium values ranging from 0.08 to 4.15 and 87Sr/86Sr ratios ranging from 0.70811 to 0.70828. This array is composed of a brine end member with an average 87Sr/86Sr of 0.70822, strontium concentrations in excess of 12.5 milligrams per liter (mg/L), and chloride concentrations exceeding 8,000 mg/L mixing with uncontaminated water similar to that in USGS06-08 with 18.0 mg/L chloride, 0.24 mg/L strontium, and a 87Sr/86Sr ratio of 0.70811. The position of samples from the City of Poplar public-water supply wells within this array indicates that brine contamination has reached all three wells. Outliers from this array are EPU-4G (groundwater from the Cretaceous Judith River Formation), brine samples from disposal wells (Huber 5-D and EPU 1-D), USGS92-11 (a well with water that was considerably contaminated in 1992 and becoming less saline with time), and PNR-27 (only slightly below the defined trend with an 87Sr/86Sr ratio of 0.70793). Water samples from the City of Poplar wells are also enriched in anions and cations that are abundant in oil-field brine.

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.

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.

Impact of transverse and longitudinal dispersion on first-order degradation rate constant estimation

NASA Astrophysics Data System (ADS)

Stenback, Greg A.; Ong, Say Kee; Rogers, Shane W.; Kjartanson, Bruce H.

2004-09-01

A two-dimensional analytical model is employed for estimating the first-order degradation rate constant of hydrophobic organic compounds (HOCs) in contaminated groundwater under steady-state conditions. The model may utilize all aqueous concentration data collected downgradient of a source area, but does not require that any data be collected along the plume centerline. Using a least squares fit of the model to aqueous concentrations measured in monitoring wells, degradation rate constants were estimated at a former manufactured gas plant (FMGP) site in the Midwest U.S. The estimated degradation rate constants are 0.0014, 0.0034, 0.0031, 0.0019, and 0.0053 day -1 for acenaphthene, naphthalene, benzene, ethylbenzene, and toluene, respectively. These estimated rate constants were as low as one-half those estimated with the one-dimensional (centerline) approach of Buscheck and Alcantar [Buscheck, T.E., Alcantar, C.M., 1995. Regression techniques and analytical solutions to demonstrate intrinsic bioremediation. In: Hinchee, R.E., Wilson, J.T., Downey, D.C. (Eds.), Intrinsic Bioremediation, Battelle Press, Columbus, OH, pp. 109-116] which does not account for transverse dispersivity. Varying the transverse and longitudinal dispersivity values over one order of magnitude for toluene data obtained from the FMGP site resulted in nearly a threefold variation in the estimated degradation rate constant—highlighting the importance of reliable estimates of the dispersion coefficients for obtaining reasonable estimates of the degradation rate constants. These results have significant implications for decision making and site management where overestimation of a degradation rate may result in remediation times and bioconversion factors that exceed expectations. For a complex source area or non-steady-state plume, a superposition of analytical models that incorporate longitudinal and transverse dispersion and time may be used at sites where the centerline method would not be applicable.

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.

Shallow ground-water flow, water levels, and quality of water, 1980-84, Cowles Unit, Indiana Dunes National Lakeshore

USGS Publications Warehouse

Cohen, D.A.; Shedlock, R.J.

1986-01-01

Since the settling ponds were sealed, the concentration of boron has decreased while concentrations of cadmium, arsenic, zinc, and molybdenum in shallow ground water downgradient of the ponds show no definite trends in time. Arsenic, boron and molybdenum have remained at concentrations above those of shallow ground water in areas unaffected by settling-pond seepage.

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

Review: A Position Paper on Selenium in Ecotoxicology: A Procedure for Deriving Site-Specific Water Quality Criteria

Treesearch

A. Dennis Lemly

1997-01-01

This paper describes a method for deriving site-specific water quality criteria for selenium using a two-step process: (1) gather information on selenium residues and biological effects at the site and in down-gradient systems and (2) examine criteria based on the degree of bioaccumulation, the relationship between mea-sured residues and threshold concentrations for...

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)

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

LaFreniere, L. M.

The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) operated a grain storage facility at the western edge of Everest, Kansas, from the early 1950s to the early 1970s. Sampling by the Kansas Department of Health and Environment (KDHE) in 1997 resulted in the detection of carbon tetrachloride in one domestic well (the Nigh well) northwest of the former facility. On behalf of the CCC/USDA, Argonne National Laboratory subsequently conducted a series of investigations to characterize the contamination (Argonne 2003, 2006a,b,c). Automatic, continuous monitoring of groundwater levels began in 2002 and is ongoing at six locations. The resultsmore » have consistently indicated groundwater flow toward the north-northwest from the former CCC/USDA property to the Nigh property, then west-southwest from the Nigh property to the intermittent creek. Sitewide periodic groundwater and surface water sampling with analysis for volatile organic compounds (VOCs) began in 2008. Argonne's combined data indicate no significant downgradient extension of contamination since 2000. At present, the sampling is annual, as approved by the KDHE (2009) in response to a plan developed for the CCC/USDA (Argonne 2009). This document presents a plan for collecting indoor air samples in homes located along and adjacent to the defined extent of the carbon tetrachloride contamination. The plan was requested by the KDHE. Ambient air samples to represent the conditions along this pathway will also be taken. The purpose of the proposed work is to satisfy KDHE requirements and to collect additional data for assessing the risk to human health due to the potential upward migration of carbon tetrachloride and its primary degradation product (chloroform) into homes located in close proximity to the former grain storage facility, as well as along and within 100 ft laterally from the currently defined plume emanating from the former Everest facility. Investigation of the indoor air environment was not a defined objective during the previous investigations of the Everest site (Argonne 2003, 2006a,b,c) as they predated the more recent regulatory concern regarding potential health risks associated with the vapor contaminant pathway.« less

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.

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.

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.

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.

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.

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.

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.

Effects of physical and geochemical heterogeneities on mineral transformation and biomass accumulation during biostimulation experiments at Rifle, Colorado.

PubMed

Li, Li; Steefel, Carl I; Kowalsky, Michael B; Englert, Andreas; Hubbard, Susan S

2010-03-01

Electron donor amendment for bioremediation often results in precipitation of secondary minerals and the growth of biomass, both of which can potentially change flow paths and the efficacy of bioremediation. Quantitative estimation of precipitate and biomass distribution has remained challenging, partly due to the intrinsic heterogeneities of natural porous media and the scarcity of field data. In this work, we examine the effects of physical and geochemical heterogeneities on the spatial distributions of mineral precipitates and biomass accumulated during a biostimulation field experiment near Rifle, Colorado. Field bromide breakthrough data were used to infer a heterogeneous distribution of hydraulic conductivity through inverse transport modeling, while the solid phase Fe(III) content was determined by assuming a negative correlation with hydraulic conductivity. Validated by field aqueous geochemical data, reactive transport modeling was used to explicitly keep track of the growth of the biomass and to estimate the spatial distribution of precipitates and biomass. The results show that the maximum mineral precipitation and biomass accumulation occurs in the vicinity of the injection wells, occupying up to 5.4vol.% of the pore space, and is dominated by reaction products of sulfate reduction. Accumulation near the injection wells is not strongly affected by heterogeneities present in the system due to the ubiquitous presence of sulfate in the groundwater. However, accumulation in the down-gradient regions is dominated by the iron-reducing reaction products, whose spatial patterns are strongly controlled by both physical and geochemical heterogeneities. Heterogeneities can lead to localized large accumulation of mineral precipitates and biomass, increasing the possibility of pore clogging. Although ignoring the heterogeneities of the system can lead to adequate prediction of the average behavior of sulfate-reducing related products, it can also lead to an overestimation of the overall accumulation of iron-reducing bacteria, as well as the rate and extent of iron reduction. Surprisingly, the model predicts that the total amount of uranium being reduced in the heterogeneous 2D system was similar to that in the 1D homogeneous system, suggesting that the overall uranium bioremediation efficacy may not be significantly affected by the heterogeneities of Fe(III) content in the down-gradient regions. Rather, the characteristics close to the vicinity of the injection wells might be crucial in determining the overall efficacy of uranium bioremediation. These findings have important implications not only for uranium bioremediation at the Rifle site and for bioremediation of other redox sensitive contaminants at sites with similar characteristics, but also for the development of optimal amendment delivery strategies in other settings. Copyright 2009 Elsevier B.V. All rights reserved.

Effects of Dual-Pump Recovery on Crude-Oil Contamination of Groundwater, Bemidji, Minnesota

NASA Astrophysics Data System (ADS)

Delin, G. N.; Herkelrath, W. N.; Lounsbury, S.

2009-12-01

In 1979 a crude-oil pipeline ruptured near Bemidji, Minnesota spilling about 1.7 million liters of crude oil onto a glacial-outwash deposit. Initial remediation efforts in 1979-80 removed about 75% of this oil. In 1983 the U.S. Geological Survey and several academic institutions began research to study the fate and transport of the petroleum hydrocarbons in the unsaturated and saturated zones at the site. In 1998 the Minnesota Pollution Control Agency (MPCA) requested that the pipeline company remove as much of the remaining oil as possible. A dual-pump recovery system was installed using five wells to remove the free-phase oil. Each well had an oil skimming pump as well as a deeper pump in the groundwater, which was used to create a cone of depression in the water table near the well. The oil/water mixture from the skimming pump was pumped to a treatment facility where the oil was separated for later removal from the site. Pumped wastewater was injected into an upgradient infiltration gallery. Despite large public and private expenditures on development and implementation of this type of remediation system, few well-documented field-scale case studies have been published. The renewed remediation presented an opportunity to document how the dissolution, biodegradation, vapor transport, and other processes changed as the site transitioned from natural attenuation to a condition of pump-and-treat remediation and back again following termination of the remediation. Impacts of the remediation were evaluated in part using measurements of oil thicknesses in wells, dissolved-oxygen concentrations in groundwater, and concentrations of methane and other gases in the unsaturated zone. The remediation from 1999 - 2004 resulted in removal of about 114,000 liters of crude oil from the site, or about 27% of the total that remained following the initial remediation in 1979-80. Although the renewed remediation decreased oil thicknesses in the immediate vicinity of remediation wells, average oil thicknesses measured in wells at the north pool (0.6 m) and south pool (0.3 m) were largely unaffected. Dissolved-oxygen measurements indicate that a new plume caused by injection of wastewater in the infiltration gallery expanded rapidly immediately following the start of the remediation in 1999. The result was an expansion of the anoxic plume of groundwater upgradient and beneath the existing natural attenuation plume. Vapor sampling results were ambiguous. From 2004-2008, CH4 and CO2 vapor concentrations decreased in upgradient areas above the floating crude oil and increased in downgradient areas above the crude oil. Conversely, O2 vapor concentrations increased in upgradient areas above the floating crude oil and decreased in downgradient areas above the crude oil. Observed changes in vapor concentrations appear to be unrelated to the renewed remediation but instead are consistent with a continuing shift in microbial population from iron reducing to methanogenic conditions. Results indicate that oil phase recovery at this site is challenging, and that considerable volumes of mobile and entrapped oil may still remain in the subsurface in spite of remediation efforts.

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

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.

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. The population of Morrill as of the 2000 census was approximately 277. All residents of Morrill now obtain their drinking water from the Sabetha municipal water system via a pipeline constructed in 1991. Starting in 1922, eight different public wells formerly servedmore » the Morrill municipal system at some time. Because of poor water quality, including high nitrate levels attributed to numerous animal feeding operations in the vicinity and application of fertilizer on agricultural lands, use of the local groundwater from any public well for municipal supply purposes was terminated in 1991 in favor of obtaining water from the Sabetha municipal water system. Investigations of the carbon tetrachloride and nitrate contamination by the Kansas Department of Health and Environment (KDHE) in 1989, 1994, and 1996 (KDHE 1989; GeoCore 1994a-e, 1996) identified a localized plume of carbon tetrachloride in groundwater extending downgradient from a grain storage facility located in the northwestern section of Morrill. The facility was formerly operated by the Commodity Credit Corporation (CCC), an agency of the U.S. Department of Agriculture (USDA), from 1950 to 1971. Since termination of the CCC/USDA grain storage operations in 1971, the property and existing grain bins have been used for private grain storage up to the present time. Prior to 1986, commercial grain fumigants were commonly used by the CCC/USDA, as well as private and commercial grain storage operations, to preserve grain. Because the identified carbon tetrachloride contamination could in part be linked to historical use of carbon tetrachloride-based fumigants at its former facility, in 2003 the CCC/USDA assumed responsibility for the site investigation of the carbon tetrachloride contamination. The CCC/USDA involvement began with development and implementation of a work plan for a Phase I expedited site characterization (Argonne 2003). That investigation and subsequent investigations (Argonne 2004, 2005a) were performed by the Environmental Science Division of Argonne National Laboratory. Argonne is a nonprofit, multidisciplinary research center operated by UChicago Argonne, LLC, for the U.S. Department of Energy (DOE). The CCC/USDA has entered into an interagency agreement with DOE, under which Argonne continues to provide technical assistance to the CCC/USDA with environmental site characterization and remediation at its former grain storage facilities. The initial investigation by the CCC/USDA in 2003 determined that soils at the former facility have not been impacted by grain fumigation activities. Neither carbon tetrachloride nor chloroform was detected in near-surface soils or in subsurface soils collected to bedrock or to a depth of 15 ft below ground level (BGL). Therefore, no identifiable human health risk is associated with either carbon tetrachloride or chloroform in shallow soils, which additionally pose no further threat of contamination to groundwater. High carbon tetrachloride concentrations in groundwater (maximum 390 {micro}g/L in a sample collected from monitoring well MW3S - located on the former CCC/USDA property - in 1995) have declined significantly during long-term monitoring by the KDHE and currently by the CCC/USDA. Maximum levels within the plume of < 50 {micro}g/L at present confirm that no continuing soil source remains at the former CCC/USDA facility. Nevertheless, carbon tetrachloride concentrations exceeding the KDHE Tier 2 risk-based screening level of 5.0 {micro}g/L remain. In September 2005, the CCC/USDA initiated periodic sampling of groundwater at Morrill, in accord with a monitoring program approved by the state (KDHE 2005), to monitor carbon tetrachloride concentrations in the groundwater. Under the KDHE-approved monitoring plan (Argonne 2005b), groundwater was initially sampled twice yearly for a period of two years. The samples were analyzed for VOCs, as well as for selected geochemical parameters to aid in the evaluation of possible natural contaminant degradation (reductive dechlorination) processes in the subsurface environment. The data have been inconclusive overall, possibly because of the relatively low contaminant concentrations in the plume. Nevertheless, consistently low levels of dissolved oxygen (DO) and oxidation-reduction potential (ORP) at monitoring well MW1D (in the deepest portion of the contaminated aquifer) and the presence of chloroform (the primary degradation product of carbon tetrachloride) suggest that some degree of reductive dechlorination is occurring.« less

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

Dam, William; Gil, Dr. April; Johnson, Raymond H.

The US Department of Energy Office of Legacy Management (LM) is responsible for maintaining protective public health and environmental conditions at former uranium mill tailings sites nationwide via long-term stewardship. One of these sites, a former uranium mill near Riverton, Wyoming, is within the boundary of the Wind River Indian Reservation and operated from 1958 to 1963. Tailings and contaminated material associated with mill operations were removed and transported to an offsite disposal cell in 1989. The remedial action was completed under Title I of the Uranium Mill Tailings Radiation Control Act of 1978. Milling operations, which included an unlinedmore » tailings impoundment and an unlined evaporation pond, contaminated the shallow groundwater, resulting in a downgradient groundwater plume that discharges to the Little Wind River. A natural flushing compliance strategy was implemented in 1998. This strategy allows contaminants of concern to naturally flush from the groundwater, provided that contaminants flush below US Environmental Protection Agency maximum concentration limits within 100 years. As part of the compliance strategy, LM has implemented a groundwater monitoring program along with institutional controls that include the installation of an alternate water supply, continued sampling of private wells, and restrictions on well drilling and gravel pit construction. LM works closely with local stakeholders and community members to ensure that these institutional controls are in place and maintained. The Riverton site provides an interesting case study where contaminant remobilization due to river flooding prompted a reevaluation of the conceptual site model to verify if the current compliance strategy would remain protective of human health and the environment. Concentrations of groundwater contaminants, which include sulfate, molybdenum, and uranium, were transiently elevated following flooding of the Little Wind River in 2010 and 2016. These flood events provided the impetus to investigate other aspects of the hydrologic system, including the unsaturated zone, naturally reduced (sulfidic) zones, and evaporite deposits. New site conceptual models, field and laboratory studies, and numerical models are being developed to explain how biogeochemical sediment–water interactions contribute to plume persistence and flood-related increases in groundwater concentrations. Updated human health and ecological risk assessments are progressing to evaluate the risk to human health and the environment based on current site conditions. Groundwater concentrations may remain above US Environmental Protection Agency maximum concentration limits beyond the 100-year natural flushing regulatory time frame. LM in its capacity as a long-term steward continues to monitor the site to ensure protectiveness is maintained and to determine the feasibility of alternative compliance and remediation strategies.« less

Transient heterogeneity in an aquifer undergoing bioremediation of hydrocarbons.

PubMed

Schillig, P C; Devlin, J F; Roberts, J A; Tsoflias, G P; McGlashan, M A

2011-01-01

Localized, transient heterogeneity was studied in a sand aquifer undergoing benzene, toluene, ethylbenzene, and xylene bioremediation using a novel array of multilevel, in situ point velocity probes (PVPs). The experiment was conducted within a sheet-pile alleyway to maintain a constant average flow direction through time. The PVPs measured changes in groundwater velocity direction and magnitude at the centimeter scale, making them ideal to monitor small-scale changes in hydraulic conductivity (K). Velocities were shown to vary nonuniformly by up to a factor of 3 when a source of oxygen was established down-gradient of the petroleum spill. In spite of these local variations, the average groundwater velocity within the 7 m × 20 m sheet-piled test area only varied within ± 25%. The nonuniform nature of the velocity variations across the gate indicated that the changes were not due solely to seasonal hydraulic gradient fluctuations. At the conclusion of the experiment, microbial biomass levels in the aquifer sediments was approximately 1 order of magnitude higher in the oxygen-amended portion of the aquifer than at the edge of the plume or in locations up-gradient of the source. These data suggest that the transient velocities resulted, at least in part, from enhanced biological activity that caused transient heterogeneities in the porous medium.

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.

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.

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.

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

Selected Natural Attenuation Monitoring Data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June 2005

USGS Publications Warehouse

Dinicola, Richard S.; Huffman, R.L.

2006-01-01

Previous investigations have shown that natural attenuation and biodegradation of chlorinated volatile organic compounds (VOCs) are substantial in shallow ground water beneath the 9-acre former landfill at Operable Unit 1 (OU-1), Naval Undersea Warfare Center, Division Keyport, Washington. The U.S. Geological Survey (USGS) has continued to monitor ground-water geochemistry to assure that conditions remain favorable for contaminant biodegradation. This report presents the ground-water geochemical and selected VOC data collected at OU-1 by the USGS during June 21-24, 2005, in support of long-term monitoring for natural attenuation. For June 2005, the strongly reducing conditions (sulfate reduction and methanogenesis) most favorable for reductive dechlorination of chlorinated VOCs were detected in fewer upper-aquifer wells than were detected during 2004. Redox conditions in ground water from the intermediate aquifer just downgradient of the landfill remained somewhat favorable for reductive dechlorination. Overall, the changes in redox conditions observed at individual wells have not been consistent or substantial throughout either the upper or the intermediate aquifers. In apparent contrast to changes in redox conditions, the chlorinated VOC concentrations were lower than previously measured in many of the piezometers in the northern phytoremediation plantation. The decrease in contaminant concentrations beneath the northern plantation and the end-product (ethane and ethene) evidence for reductive dechlorination are consistent with 2000-04 results. In the southern phytoremediation plantation, changes in chlorinated VOC concentrations were variable. Most notable was a substantial decrease in the sum of trichloroethene, cis-1,2-dichloroethene, and vinyl chloride concentrations at piezometer P1-9 from 75,000 to 1,000 micrograms per liter between 2004 and 2005. The high concentrations of the reductive dechlorination end-products ethane and ethene measured at the most contaminated sites (P1-6 and P1-7), as well as measurable concentrations at sites P1-9 and P1-10, are reliable evidence that reductive dechlorination of chlorinated VOCs is ongoing in the southern plantation. In the 10 passive-diffusion samplers deployed beneath the marsh stream, the highest chlorinated VOC concentrations measured were at a site (S-4) about midway along the sampled stream reach. In 2005, the sum of trichloroethene, cis-1,2-dichloroethene, and vinyl chloride concentrations increased nearly twofold in comparison to 2004. It is not certain that the apparent increase in concentrations is representative of site conditions. However, the chlorinated VOC concentrations have increased each time at the two most contaminated passive-diffusion sampler sites that have been sampled for multiple years. In the marsh stream, chlorinated VOC concentrations in surface water were low at the site (SW-S6) near the upgradient margin of the former landfill. Concentrations in the stream increased substantially after flowing past the southern phytoremediation plantation to the downstream site (MA-12). Overall, the 2005 data were consistent with previous findings of continued biodegradation of chlorinated VOCs in ground water, along with continued discharge of some chlorinated VOCs to surface water in the marsh stream.

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.

Final report for DOE Grant No. DE-SC0006609 - Persistence of Microbially Facilitated Calcite Precipitation as an in situ Treatment for Strontium-90

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

Smith, Robert W.; Fujita, Yoshiko; Hubbard, Susan S.

2013-11-15

Subsurface radionuclide and metal contaminants throughout the U.S. Department of Energy (DOE) complex pose one of DOE's greatest challenges for long-term stewardship. One promising stabilization mechanism for divalent ions, such as the short-lived radionuclide 90Sr, is co-precipitation in calcite. We have previously found that nutrient addition can stimulate microbial ureolytic activity, that this activity accelerates calcite precipitation and co-precipitation of Sr, and that higher calcite precipitation rates can result in increased Sr partitioning. We have conducted integrated field, laboratory, and computational research to evaluate the relationships between ureolysis and calcite precipitation rates and trace metal partitioning under environmentally relevant conditions,more » and investigated the coupling between flow/flux manipulations and precipitate distribution. A field experimental campaign conducted at the Integrated Field Research Challenge (IFRC) site located at Rifle, CO was based on a continuous recirculation design; water extracted from a down-gradient well was amended with urea and molasses (a carbon and electron donor) and re-injected into an up-gradient well. The goal of the recirculation design and simultaneous injection of urea and molasses was to uniformly accelerate the hydrolysis of urea and calcite precipitation over the entire inter-wellbore zone. The urea-molasses recirculation phase lasted, with brief interruptions for geophysical surveys, for 12 days and was followed by long-term monitoring which continued for 13 months. A post experiment core located within the inter-wellbore zone was collected on day 321 and characterized with respect to cation exchange capacity, mineral carbonate content, urease activity, ureC gene abundance, extractable ammonium (a urea hydrolysis product) content, and the 13C isotopic composition of solid carbonates. It was also subjected to selective extractions for strontium and uranium. Result of the core characterization suggest that urea hydrolysis occurred primarily within the upper portion of the inter-wellbore zone and that strontium was mobilized from cation exchange sites and subsequently co-precipitated with new calcium carbonate.« less

Evaluation of Groundwater Pathways and Travel Times From the Nevada Test Site to the Potential Yucca Mountain Repository

NASA Astrophysics Data System (ADS)

Pohlmann, K. F.; Zhu, J.; Ye, M.; Carroll, R. W.; Chapman, J. B.; Russell, C. E.; Shafer, D. S.

2006-12-01

Yucca Mountain (YM), Nevada has been recommended as a deep geological repository for the disposal of spent fuel and high-level radioactive waste. If YM is licensed as a repository by the Nuclear Regulatory Commission, it will be important to identify the potential for radionuclides to migrate from underground nuclear testing areas located on the Nevada Test Site (NTS) to the hydraulically downgradient repository area to ensure that monitoring does not incorrectly attribute repository failure to radionuclides originating from other sources. In this study, we use the Death Valley Regional Flow System (DVRFS) model developed by the U.S. Geological Survey to investigate potential groundwater migration pathways and associated travel times from the NTS to the proposed YM repository area. Using results from the calibrated DVRFS model and the particle tracking post-processing package MODPATH we modeled three-dimensional groundwater advective pathways in the NTS and YM region. Our study focuses on evaluating the potential for groundwater pathways between the NTS and YM withdrawal area and whether travel times for advective flow along these pathways coincide with the prospective monitoring time frame at the proposed repository. We include uncertainty in effective porosity as this is a critical variable in the determination of time for radionuclides to travel from the NTS region to the YM withdrawal area. Uncertainty in porosity is quantified through evaluation of existing site data and expert judgment and is incorporated in the model through Monte Carlo simulation. Since porosity information is limited for this region, the uncertainty is quite large and this is reflected in the results as a large range in simulated groundwater travel times.

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)

Evaluation of Technetium Getters to Improve the Performance of Cast Stone

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

Neeway, James J.; Qafoku, Nikolla P.; Serne, R. Jeffrey

2015-11-01

Cast Stone has been selected as the preferred waste form for solidification of aqueous secondary liquid effluents from the Hanford Tank Waste Treatment and Immobilization Plant (WTP) process condensates and low-activity waste (LAW) melter off-gas caustic scrubber effluents. Cast Stone is also being evaluated as a supplemental immobilization technology to provide the necessary LAW treatment capacity to complete the Hanford tank waste cleanup mission in a timely and cost effective manner. One of the major radionuclides that Cast Stone has the potential to immobilize is technetium (Tc). The mechanism for immobilization is through the reduction of the highly mobile Tc(VII)more » species to the less mobile Tc(IV) species by the blast furnace slag (BFS) used in the Cast Stone formulation. Technetium immobilization through this method would be beneficial because Tc is one of the most difficult contaminants to address at the U.S. Department of Energy (DOE) Hanford Site due to its complex chemical behavior in tank waste, limited incorporation in mid- to high-temperature immobilization processes (vitrification, steam reformation, etc.), and high mobility in subsurface environments. In fact, the Tank Closure and Waste Management Environmental Impact Statement for the Hanford Site, Richland, Washington (TC&WM EIS) identifies technetium-99 ( 99Tc) as one of the radioactive tank waste components contributing the most to the environmental impact associated with the cleanup of the Hanford Site. The TC&WM EIS, along with an earlier supplemental waste-form risk assessment, used a diffusion-limited release model to estimate the release of different contaminants from the WTP process waste forms. In both of these predictive modeling exercises, where effective diffusivities based on grout performance data available at the time, groundwater at the 100-m down-gradient well exceeded the allowable maximum permissible concentrations for 99Tc. (900 pCi/L). Recent relatively short-term (63 day) leach tests conducted on both LAW and secondary waste Cast Stone monoliths indicated that 99Tc diffusivities were at or near diffusivities where the groundwater at the 100-m down-gradient well would exceed the allowable maximum permissible 99Tc concentrations. There is, therefore, a need and an opportunity to improve the retention of Tc in the Cast Stone waste form. One method to improve the performance of the Cast Stone waste form is through the addition of “getters” that selectively sequester Tc inside Cast Stone.« less

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

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)

Tetracycline residues and tetracycline resistance genes in groundwater impacted by swine production facilities

USGS Publications Warehouse

Mackie, R.I.; Koike, S.; Krapac, I.; Chee-Sanford, J.; Maxwell, Susan; Aminov, R.I.

2006-01-01

Antibiotics are used at therapeutic levels to treat disease; at slightly lower levels as prophylactics; and at low, subtherapeutic levels for growth promotion and improvement of feed efficiency. Over 88% of swine producers in the United States gave antimicrobials to grower/finisher pigs in feed as a growth promoter in 2000. It is estimated that ca. 75% of antibiotics are not absorbed by animals and are excreted in urine and feces. The extensive use of antibiotics in swine production has resulted in antibiotic resistance in many intestinal bacteria, which are also excreted in swine feces, resulting in dissemination of resistance genes into the environment.To assess the impact of manure management on groundwater quality, groundwater samples have been collected near two swine confinement facilities that use lagoons for manure storage and treatment. Several key contaminant indicators-including inorganic ions, antibiotics, and antibiotic resistance genes-were analyzed in groundwater collected from the monitoring wells. Chloride, ammonium, potassium, and sodium were predominant inorganic constituents in the manure samples and served as indicators of groundwater contamination. Based on these analyses, shallow groundwater has been impacted by lagoon seepage at both sites. Liquid chromatography-mass spectroscopy (LC-MS) was used to measure the dissolved concentrations of tetracycline, chlortetracycline, and oxytetracycline in groundwater and manure. Although tetracyclines were regularly used at both facilities, they were infrequently detected in manure samples and then at relatively trace concentrations. Concentrations of all tetracyclines and their breakdown products in the groundwater sampled were generally less than 0.5 ??g/L.Bacterial tetracycline resistance genes served as distinct genotypic markers to indicate the dissemination and mobility of antibiotic resistance genes that originated from the lagoons. Applying PCR to genomic DNA extracted from the lagoon and groundwater samples, four commonly occurring tetracycline (tet) resistance genes-tet(M), tet(O), tet(Q), and tet(W)-were detected. The detection frequency of tet genes was much higher in wells located closer to and down-gradient from the lagoons than in wells more distant from the lagoons. These results suggested that in the groundwater underlying both facilities tetracycline resistance genes exist and are somewhat persistent, but that the distribution and potentially the flux for each tet gene varied throughout the study period.

Long-term pumping test to study the impact of an open-loop geothermal system on seawater intrusion in a coastal aquifer: the case study of Bari (Southern Italy)

NASA Astrophysics Data System (ADS)

Clementina Caputo, Maria; Masciale, Rita; Masciopinto, Costantino; De Carlo, Lorenzo

2016-04-01

The high cost and scarcity of fossil fuels have promoted the increased use of natural heat for a number of direct applications. Just as for fossil fuels, the exploitation of geothermal energy should consider its environmental impact and sustainability. Particular attention deserves the so-called open loop geothermal groundwater heat pump (GWHP) system, which uses groundwater as geothermal fluid. From an economic point of view, the implementation of this kind of geothermal system is particularly attractive in coastal areas, which have generally shallow aquifers. Anyway the potential problem of seawater intrusion has led to laws that restrict the use of groundwater. The scarcity of freshwater could be a major impediment for the utilization of geothermal resources. In this study a new methodology has been proposed. It was based on an experimental approach to characterize a coastal area in order to exploit the low-enthalpy geothermal resource. The coastal karst and fractured aquifer near Bari, in Southern Italy, was selected for this purpose. For the purpose of investigating the influence of an open-loop GWHP system on the seawater intrusion, a long-term pumping test was performed. The test simulated the effects of a prolonged withdrawal on the chemical-physical groundwater characteristics of the studied aquifer portion. The duration of the test was programmed in 16 days, and it was performed with a constant pumping flowrate of 50 m3/h. The extracted water was outflowed into an adjacent artificial channel, by means of a piping system. Water depth, temperature and electrical conductivity of the pumped water were monitored for 37 days, including also some days before and after the pumping duration. The monitored parameters, collected in the pumping and in five observation wells placed 160 m down-gradient with respect to the groundwater flow direction, have been used to estimate different scenarios of the impact of the GWHP system on the seawater intrusion by mean of a numerical model. Model flow simulations were carried out under transient flow conditions, in order to determine perturbations of the saline front into the Bari fractured aquifer, caused by the long-term pumping at 50 m3/h.

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.

Nitrate Remediation of Soil and Groundwater Using Phytoremediation: Transfer of Nitrogen Containing Compounds from the Subsurface to Surface Vegetation

NASA Astrophysics Data System (ADS)

Nelson, Sheldon

2013-04-01

Nitrate Remediation of Soil and Groundwater Using Phytoremediation: Transfer of Nitrogen Containing Compounds from the Subsurface to Surface Vegetation Sheldon Nelson Chevron Energy Technology Company 6001 Bollinger Canyon Road San Ramon, California 94583 snne@chevron.com The basic concept of using a plant-based remedial approach (phytoremediation) for nitrogen containing compounds is the incorporation and transformation of the inorganic nitrogen from the soil and/or groundwater (nitrate, ammonium) into plant biomass, thereby removing the constituent from the subsurface. There is a general preference in many plants for the ammonium nitrogen form during the early growth stage, with the uptake and accumulation of nitrate often increasing as the plant matures. The synthesis process refers to the variety of biochemical mechanisms that use ammonium or nitrate compounds to primarily form plant proteins, and to a lesser extent other nitrogen containing organic compounds. The shallow soil at the former warehouse facility test site is impacted primarily by elevated concentrations of nitrate, with a minimal presence of ammonium. Dissolved nitrate (NO3-) is the primary dissolved nitrogen compound in on-site groundwater, historically reaching concentrations of 1000 mg/L. The initial phases of the project consisted of the installation of approximately 1750 trees, planted in 10-foot centers in the areas impacted by nitrate and ammonia in the shallow soil and groundwater. As of the most recent groundwater analytical data, dissolved nitrate reductions of 40% to 96% have been observed in monitor wells located both within, and immediately downgradient of the planted area. In summary, an evaluation of time series groundwater analytical data from the initial planted groves suggests that the trees are an effective means of transfering nitrogen compounds from the subsurface to overlying vegetation. The mechanism of concentration reduction may be the uptake of residual nitrate from the vadose zone, the direct uptake of dissolved constituent from the upper portion of the saturated zone/capillary fringe, or a combination of these two processes.

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.

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.

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.

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

Managed aquifer recharge of treated wastewater: water quality changes resulting from infiltration through the vadose zone.

PubMed

Bekele, Elise; Toze, Simon; Patterson, Bradley; Higginson, Simon

2011-11-01

Secondary treated wastewater was infiltrated through a 9 m-thick calcareous vadose zone during a 39 month managed aquifer recharge (MAR) field trial to determine potential improvements in the recycled water quality. The water quality improvements of the recycled water were based on changes in the chemistry and microbiology of (i) the recycled water prior to infiltration relative to (ii) groundwater immediately down-gradient from the infiltration gallery. Changes in the average concentrations of several constituents in the recycled water were identified with reductions of 30% for phosphorous, 66% for fluoride, 62% for iron and 51% for total organic carbon when the secondary treated wastewater was infiltrated at an applied rate of 17.5 L per minute with a residence time of approximately four days in the vadose zone and less than two days in the aquifer. Reductions were also noted for oxazepam and temazepam among the pharmaceuticals tested and for a range of microbial pathogens, but reductions were harder to quantify as their magnitudes varied over time. Total nitrogen and carbamazepine persisted in groundwater down-gradient from the infiltration galleries. Infiltration does potentially offer a range of water quality improvements over direct injection to the water table without passage through the unsaturated zone; however, additional treatment options for the non-potable water may still need to be considered, depending on the receiving environment or the end use of the recovered water. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

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.

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.

A tiered approach to distinguish sources of gasoline and diesel spills.

PubMed

Xiong, Wenhui; Bernesky, Ryan; Bechard, Robert; Michaud, Guy; Lang, Jeremy

2014-07-15

Approximately 11% and 25% of annual Canadian oil spill accidents are gasoline and diesel spills, respectively. Gasoline and diesel spills are a challenge to conventional environmental forensic techniques because refinery processes remove most of the higher molecular weight biomarkers. This study presents a tiered environmental forensics strategy that includes such information as site operational history, geology/hydrogeology, GC/FID pre-screening, volatile GC/MS, semi-volatile GC/MS, and GC/MS selected ion monitoring (SIM) chromatograms for fingerprinting of gasoline and diesel spills. GC/FID pre-screening analysis identified the presence of two individual gasoline and diesel plumes at a fuel service station (study site). The gasoline plume is present between the upgradient fuel underground storage tanks (USTs) and the downgradient diesel plume, suggesting that the diesel impacts to groundwater may not be originated from the current UST leakage. Similar distribution of C3-alkylbenzenes (the most stable chemicals in gasoline) and the consistent diagnostic ratios of the analyte pairs with similar solubility indicate that the source for the dissolved gasoline constituents in the gasoline impacted zone likely originated from a gasoline leakage from the current USTs on the study site. In the diesel impacted zone, the distinct distribution and diagnostic ratios of sesquiterpanes (biomarkers for diesel) and alkylated PAHs confirm that the diesel plume originate from different crude oil sources than the current USTs. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

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

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

The Chemistry and Flow Dynamics of Molecular Biological Tools Used to Confirm In Situ Bioremediation of Benzene, TBA, and MTBE

NASA Astrophysics Data System (ADS)

North, K. P.; Mackay, D. M.; Scow, K. M.

2010-12-01

In situ bioremediation has typically been confirmed by collecting sediment and groundwater samples to directly demonstrate a degradation process in a laboratory microcosm. However, recent advances in molecular biological tools present options for demonstrating degradation processes with field-based tools that are less time-consuming. We have been investigating the capability of some of these molecular biological tools to evaluate in situ biodegradation of tert-butyl alcohol (TBA), methyl tert-butyl ether (MTBE), and benzene at two field sites in California. At both sites, we have deployed Bio-Traps® (“traps”), made of Bio-Sep® beads in slotted PVC pipe, which provide ideal environments for microbial colonization. Stable Isotope Probing can be accomplished by sorbing the13C-labeled organic contaminant of concern onto Bio-Sep® beads (“baiting”); incorporation of 13C into the biomass collected by the trap would indicate that the microbial community was capable of degrading the labeled compound. In addition, we examined the chemistry and flow dynamics of these traps and present those results here. We performed a field experiment and a lab experiment to, in part, define the rate that different baits leached off various traps. At a TBA- and MTBE-contaminated site at Vandenberg AFB, Lompoc, CA, the TBA-dominant plume was effectively treated by recirculation/oxygenation of groundwater, decreasing TBA and MTBE concentrations to detection limits along predicted flowpaths created by two pairs of recirculation wells. We used the generated aerobic treatment zone to deploy traps baited with 13C-labeled MTBE or TBA in a novel, ex situ experimental setup. The groundwater flow extracted from the aerobic treatment zone was split through several chambers, each containing a trap and monitoring of influent and effluent. The chamber effluent was measured throughout a six-week deployment and analyzed for both TBA and MTBE; the majority of mass leached from the baited traps did so within the first eight days. The lab experiment assessed a trap designed as an in situ microcosm, containing 13C-labeled benzene and a sulfate source, in order to quantify the amount of benzene leached from the trap and the rate of sulfate dissolution into the surrounding area. An “aquifer” was built in a tank and designed to mimic the well installations at a benzene-contaminated, sulfate-reducing site in Fillmore, CA. Multi-level upgradient and downgradient monitoring points were sampled throughout the six-week deployment and analyzed for sulfate and benzene. The trap and “aquifer” chemistry will be discussed and compared to the field experiment results.

Selected Natural Attenuation Monitoring Data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June 2006

USGS Publications Warehouse

Dinicola, R.S.; Huffman, R.L.

2007-01-01

Previous investigations have shown that natural attenuation and biodegradation of chlorinated volatile organic compounds (VOCs) are substantial in shallow ground water beneath the 9-acre former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center, Division Keyport, Washington. The U.S. Geological Survey (USGS) has continued to monitor ground-water geochemistry to assure that conditions remain favorable for contaminant biodegradation. This report presents ground-water geochemical and selected VOC data collected at OU 1 by the USGS during June 12-14, 2006, in support of long-term monitoring for natural attenuation. For June 2006, the strongly reducing conditions (sulfate reduction and methanogenesis) most favorable for reductive dechlorination of VOCs were inferred for 5 of 15 upper-aquifer sites in the northern and southern phytoremediation plantations. Predominant redox conditions in ground water from the intermediate aquifer just downgradient from the landfill remained mildly reducing and somewhat favorable for reductive dechlorination. Since about 2003, measured dissolved hydrogen concentrations in the upper aquifer generally have been lower than those previously measured, although methane and sulfide have continued to be detected throughout the upper aquifer beneath the landfill. Overall, no widespread changes in ground-water redox conditions were measured that should result in either more or less efficient biodegradation of chlorinated VOCs. For the northern plantation in 2006, chlorinated VOC concentrations at piezometers P1-3 and P1-4 were lower than previously measured, and trichloroethene (TCE), cis-1,2-dichloroethene (cis-DCE), or vinyl chloride (VC) were not detected at piezometers P1-1 and P1-5. The steady decrease in contaminant concentrations and the continued detection of the reductive dechlorination end-products ethene and ethane have been consistent throughout the upper aquifer beneath the northern plantation. For the southern plantation in 2006, changes in chlorinated VOC concentrations at the piezometers were highly variable. At piezometer P1-9, the 2006 total chlorinated VOC concentration as well as the concentrations of cis-DCE and VC were measured at their highest levels to date; contaminant concentrations substantially decreased at piezometer P1-9 between June 2004 and June 2005. The reasons for the 2004-05 decrease in concentrations or the 2005-06 increase in concentrations are unknown. At piezometer P1-10, the consistent temporal trend of decreasing chlorinated VOC concentrations measured since 1999 ended, and the concentration of total chlorinated VOC in 2006 was the highest measured since 1999. The reductive dechlorination end-product ethene was measured at concentrations as high as 1,300 micrograms per liter in the upper aquifer beneath the southern plantation, which is reliable evidence that reductive dechlorination of VOCs is ongoing.

317/319 phytoremediation site monitoring report - 2004 growing season.

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

Negri, M. C.; Gopalakrishnan, G.; Bogner, J.

2009-02-21

In 1999, Argonne National Laboratory (ANL) designed and installed a series of engineered plantings consisting of a vegetative cover system and approximately 800 hybrid poplars and willows rooting at various predetermined depths. The plants were installed using various methods including Applied Natural Science's TreeWell{reg_sign} system. The goal of the installation was to protect downgradient surface and groundwater by hydraulic control of the contaminated plume by intercepting the contaminated groundwater with the tree roots, removing moisture from the upgradient soil area, reducing water infiltration, preventing soil erosion, degrading and/or transpiring the residual volatile organic compounds (VOCs), and removing tritium from themore » subsoil and groundwater. This report presents the results of the monitoring activities conducted by Argonne's Energy Systems Division (ES) in the growing season of 2004. Monitoring of the planted trees began soon after the trees were installed in 1999 and has been conducted every summer since then. As the trees grew and consolidated their growth into the contaminated soil and groundwater, their exposure to the contaminants was progressively shown through tissue sampling. Since the inception of the project, significant progress was made in the refinement and testing of the analytical method (for which no official method is available), the determination of the optimal tissue for sampling, and of the variability of the concentrations within a specific tree. An understanding has also been developed on background concentrations of VOCs, and how to discriminate between VOCs that are associated with plant tissue because of aerial or of soil/groundwater uptake pathways. Also, during the 2003 sampling campaign, core samples from tree trunks were collected for the first time (the trees were large enough to stand the procedure). Data collected from the French Drain area last year supported the hypothesis that a correlation was present between concentrations of VOCs in the soil and in corresponding branch tissue. During this year (2004), systematic data collection in the French Drain area further consolidated this correlation and indicated that trees are clearly in the condition to have reached the target rooting depth. Concentrations in the hundreds of ppb in branch and trunk samples confirm that uptake can be a quantitative way to remove VOCs from the contaminated media. Additionally, laboratory studies were conducted in 2004 to determine mass recoveries from leaves and branches using the headspace method, and to determine if we could further modify our sample pretreatment method to ensure optimal recovery. Results showed that the recovery of TCE in leaves and branches with our current method ranged between 98 and 138%, indicating that most of the TCE present in the samples is recovered during the analysis. Freezing and heating had variable results in recovery rates, which resulted in no significant changes being introduced to the current SOP.« less

Evaluation of multiple tracer methods to estimate low groundwater flow velocities.

PubMed

Reimus, Paul W; Arnold, Bill W

2017-04-01

Four different tracer methods were used to estimate groundwater flow velocity at a multiple-well site in the saturated alluvium south of Yucca Mountain, Nevada: (1) two single-well tracer tests with different rest or "shut-in" periods, (2) a cross-hole tracer test with an extended flow interruption, (3) a comparison of two tracer decay curves in an injection borehole with and without pumping of a downgradient well, and (4) a natural-gradient tracer test. Such tracer methods are potentially very useful for estimating groundwater velocities when hydraulic gradients are flat (and hence uncertain) and also when water level and hydraulic conductivity data are sparse, both of which were the case at this test location. The purpose of the study was to evaluate the first three methods for their ability to provide reasonable estimates of relatively low groundwater flow velocities in such low-hydraulic-gradient environments. The natural-gradient method is generally considered to be the most robust and direct method, so it was used to provide a "ground truth" velocity estimate. However, this method usually requires several wells, so it is often not practical in systems with large depths to groundwater and correspondingly high well installation costs. The fact that a successful natural gradient test was conducted at the test location offered a unique opportunity to compare the flow velocity estimates obtained by the more easily deployed and lower risk methods with the ground-truth natural-gradient method. The groundwater flow velocity estimates from the four methods agreed very well with each other, suggesting that the first three methods all provided reasonably good estimates of groundwater flow velocity at the site. The advantages and disadvantages of the different methods, as well as some of the uncertainties associated with them are discussed. Published by Elsevier B.V.

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

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.

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.

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.

Evaluation of a scalar eddy transport coefficient based on geometric constraints

NASA Astrophysics Data System (ADS)

Bachman, S. D.; Marshall, D. P.; Maddison, J. R.; Mak, J.

2017-01-01

A suite of idealized models is used to evaluate and compare several previously proposed scalings for the eddy transport coefficient in downgradient mesoscale eddy closures. Of special interest in this comparison is a scaling introduced as part of the eddy parameterization framework of Marshall et al. (2012), which is derived using the inherent geometry of the Eliassen-Palm eddy flux tensor. The primary advantage of using this coefficient in a downgradient closure is that all dimensional terms are explicitly specified and the only uncertainty is a nondimensional parameter, α, which is bounded by one in magnitude. In each model a set of passive tracers is initialized, whose flux statistics are used to invert for the eddy-induced tracer transport. Unlike previous work, where this technique has been employed to diagnose the tensor coefficient of a linear flux-gradient relationship, the idealization of these models allows the lateral eddy transport to be described by a scalar coefficient. The skill of the extant scalings is then measured by comparing their predicted values against the coefficients diagnosed using this method. The Marshall et al. (2012), scaling is shown to scale most closely with the diagnosed coefficients across all simulations. It is shown that the skill of this scaling is due to its functional dependence on the total eddy energy, and that this scaling provides an excellent match to the diagnosed fluxes even in the limit of constant α. Possible extensions to this work, including how to incorporate the resultant transport coefficient into the Gent and McWilliams parameterization, are discussed.

A new paradigm for predicting zonal-mean climate and climate change

NASA Astrophysics Data System (ADS)

Armour, K.; Roe, G.; Donohoe, A.; Siler, N.; Markle, B. R.; Liu, X.; Feldl, N.; Battisti, D. S.; Frierson, D. M.

2016-12-01

How will the pole-to-equator temperature gradient, or large-scale patterns of precipitation, change under global warming? Answering such questions typically involves numerical simulations with comprehensive general circulation models (GCMs) that represent the complexities of climate forcing, radiative feedbacks, and atmosphere and ocean dynamics. Yet, our understanding of these predictions hinges on our ability to explain them through the lens of simple models and physical theories. Here we present evidence that zonal-mean climate, and its changes, can be understood in terms of a moist energy balance model that represents atmospheric heat transport as a simple diffusion of latent and sensible heat (as a down-gradient transport of moist static energy, with a diffusivity coefficient that is nearly constant with latitude). We show that the theoretical underpinnings of this model derive from the principle of maximum entropy production; that its predictions are empirically supported by atmospheric reanalyses; and that it successfully predicts the behavior of a hierarchy of climate models - from a gray radiation aquaplanet moist GCM, to comprehensive GCMs participating in CMIP5. As an example of the power of this paradigm, we show that, given only patterns of local radiative feedbacks and climate forcing, the moist energy balance model accurately predicts the evolution of zonal-mean temperature and atmospheric heat transport as simulated by the CMIP5 ensemble. These results suggest that, despite all of its dynamical complexity, the atmosphere essentially responds to energy imbalances by simply diffusing latent and sensible heat down-gradient; this principle appears to explain zonal-mean climate and its changes under global warming.

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.

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.

Tracer test with As(V) under variable redox conditions controlling arsenic transport in the presence of elevated ferrous iron concentrations

USGS Publications Warehouse

Hohn, R.; Isenbeck-Schroter, M.; Kent, D.B.; Davis, J.A.; Jakobsen, R.; Jann, S.; Niedan, V.; Scholz, C.; Stadler, S.; Tretner, A.

2006-01-01

To study transport and reactions of arsenic under field conditions, a small-scale tracer test was performed in an anoxic, iron-reducing zone of a sandy aquifer at the USGS research site on Cape Cod, Massachusetts, USA. For four weeks, a stream of groundwater with added As(V) (6.7????M) and bromide (1.6??mM), was injected in order to observe the reduction of As(V) to As(III). Breakthrough of bromide (Br-), As(V), and As(III) as well as additional parameters characterizing the geochemical conditions was observed at various locations downstream of the injection well over a period of 104??days. After a short lag period, nitrate and dissolved oxygen from the injectate oxidized ferrous iron and As(V) became bound to the freshly formed hydrous iron oxides. Approximately one week after terminating the injection, anoxic conditions had been reestablished and increases in As(III) concentrations were observed within 1??m of the injection. During the observation period, As(III) and As(V) were transported to a distance of 4.5??m downgradient indicating significant retardation by sorption processes for both species. Sediment assays as well as elevated concentrations of hydrogen reflected the presence of As(V) reducing microorganisms. Thus, microbial As(V) reduction was thought to be one major process driving the release of As(III) during the tracer test in the Cape Cod aquifer. ?? 2006 Elsevier B.V. All rights reserved.

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.

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.

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.

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.

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.

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.

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

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.

Sorption testing and generalized composite surface complexation models for determining uranium sorption parameters at a proposed in-situ recovery site

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

Johnson, Raymond H.; Truax, Ryan A.; Lankford, David A.

Solid-phase iron concentrations and generalized composite surface complexation models were used to evaluate procedures in determining uranium sorption on oxidized aquifer material at a proposed U in situ recovery (ISR) site. At the proposed Dewey Burdock ISR site in South Dakota, USA, oxidized aquifer material occurs downgradient of the U ore zones. Solid-phase Fe concentrations did not explain our batch sorption test results,though total extracted Fe appeared to be positively correlated with overall measured U sorption. Batch sorption test results were used to develop generalized composite surface complexation models that incorporated the full genericsorption potential of each sample, without detailedmore » mineralogiccharacterization. The resultant models provide U sorption parameters (site densities and equilibrium constants) for reactive transport modeling. The generalized composite surface complexation sorption models were calibrated to batch sorption data from three oxidized core samples using inverse modeling, and gave larger sorption parameters than just U sorption on the measured solidphase Fe. These larger sorption parameters can significantly influence reactive transport modeling, potentially increasing U attenuation. Because of the limited number of calibration points, inverse modeling required the reduction of estimated parameters by fixing two parameters. The best-fit models used fixed values for equilibrium constants, with the sorption site densities being estimated by the inversion process. While these inverse routines did provide best-fit sorption parameters, local minima and correlated parameters might require further evaluation. Despite our limited number of proxy samples, the procedures presented provide a valuable methodology to consider for sites where metal sorption parameters are required. Furthermore, these sorption parameters can be used in reactive transport modeling to assess downgradient metal attenuation, especially when no other calibration data are available, such as at proposed U ISR sites.« less

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

Refining the site conceptual model at a former uranium mill site in Riverton, Wyoming, USA

DOE PAGES

Dam, William; Campbell, Sam; Johnson, Ray; ...

2015-07-07

Milling activities at a former uranium mill site near Riverton, Wyoming, USA, contaminated the shallow groundwater beneath and downgradient of the site. Although the mill operated for <6 years (1958-1963), its impact remains an environmental liability. Groundwater modeling predicted that contaminant concentrations were declining steadily, which confirmed the conceptual site model (CSM). However, local flooding in 2010 mobilized contaminants that migrated downgradient from the Riverton site and resulted in a dramatic increase in groundwater contaminant concentrations. This observation indicated that the original CSM was inadequate to explain site conditions and needed to be refined. In response to the new observationsmore » after the flood, a collaborative investigation to better understand site conditions and processes commenced. This investigation included installing 103 boreholes to collect soil and groundwater samples, sampling and analysis of evaporite minerals along the bank of the Little Wind River, an analysis of evaportranspiration in the shallow aquifer, and sampling naturally organic-rich sediments near groundwater discharge areas. The enhanced characterization revealed that the existing CSM did not account for high uranium concentrations in groundwater remaining on the former mill site and groundwater plume stagnation near the Little Wind River. Observations from the flood and subsequent investigations indicate that additional characterization is still needed to continue refining the CSM and determine the viability of the natural flushing compliance strategy. Additional sampling, analysis, and testing of soil and groundwater are necessary to investigate secondary contaminant sources, mobilization of contaminants during floods, geochemical processes, contaminant plume stagnation, distribution of evaporite minerals and organic-rich sediments, and mechanisms and rates of contaminant transfer from soil to groundwater. Future data collection will be used to continually revise the CSM and evaluate the compliance strategy at the site.« less

Sorption testing and generalized composite surface complexation models for determining uranium sorption parameters at a proposed in-situ recovery site

DOE PAGES

Johnson, Raymond H.; Truax, Ryan A.; Lankford, David A.; ...

2016-02-03

Solid-phase iron concentrations and generalized composite surface complexation models were used to evaluate procedures in determining uranium sorption on oxidized aquifer material at a proposed U in situ recovery (ISR) site. At the proposed Dewey Burdock ISR site in South Dakota, USA, oxidized aquifer material occurs downgradient of the U ore zones. Solid-phase Fe concentrations did not explain our batch sorption test results,though total extracted Fe appeared to be positively correlated with overall measured U sorption. Batch sorption test results were used to develop generalized composite surface complexation models that incorporated the full genericsorption potential of each sample, without detailedmore » mineralogiccharacterization. The resultant models provide U sorption parameters (site densities and equilibrium constants) for reactive transport modeling. The generalized composite surface complexation sorption models were calibrated to batch sorption data from three oxidized core samples using inverse modeling, and gave larger sorption parameters than just U sorption on the measured solidphase Fe. These larger sorption parameters can significantly influence reactive transport modeling, potentially increasing U attenuation. Because of the limited number of calibration points, inverse modeling required the reduction of estimated parameters by fixing two parameters. The best-fit models used fixed values for equilibrium constants, with the sorption site densities being estimated by the inversion process. While these inverse routines did provide best-fit sorption parameters, local minima and correlated parameters might require further evaluation. Despite our limited number of proxy samples, the procedures presented provide a valuable methodology to consider for sites where metal sorption parameters are required. Furthermore, these sorption parameters can be used in reactive transport modeling to assess downgradient metal attenuation, especially when no other calibration data are available, such as at proposed U ISR sites.« 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.

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.

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.

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.

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

Dam, William; Campbell, Sam; Johnson, Ray

Milling activities at a former uranium mill site near Riverton, Wyoming, USA, contaminated the shallow groundwater beneath and downgradient of the site. Although the mill operated for <6 years (1958-1963), its impact remains an environmental liability. Groundwater modeling predicted that contaminant concentrations were declining steadily, which confirmed the conceptual site model (CSM). However, local flooding in 2010 mobilized contaminants that migrated downgradient from the Riverton site and resulted in a dramatic increase in groundwater contaminant concentrations. This observation indicated that the original CSM was inadequate to explain site conditions and needed to be refined. In response to the new observationsmore » after the flood, a collaborative investigation to better understand site conditions and processes commenced. This investigation included installing 103 boreholes to collect soil and groundwater samples, sampling and analysis of evaporite minerals along the bank of the Little Wind River, an analysis of evaportranspiration in the shallow aquifer, and sampling naturally organic-rich sediments near groundwater discharge areas. The enhanced characterization revealed that the existing CSM did not account for high uranium concentrations in groundwater remaining on the former mill site and groundwater plume stagnation near the Little Wind River. Observations from the flood and subsequent investigations indicate that additional characterization is still needed to continue refining the CSM and determine the viability of the natural flushing compliance strategy. Additional sampling, analysis, and testing of soil and groundwater are necessary to investigate secondary contaminant sources, mobilization of contaminants during floods, geochemical processes, contaminant plume stagnation, distribution of evaporite minerals and organic-rich sediments, and mechanisms and rates of contaminant transfer from soil to groundwater. Future data collection will be used to continually revise the CSM and evaluate the compliance strategy at the site.« 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.

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.

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.

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.

Prediction of Breakthrough Curves for Conservative and Reactive Transport from the Structural Parameters of Highly Heterogeneous Media

NASA Astrophysics Data System (ADS)

Hansen, S. K.; Haslauer, C. P.; Cirpka, O. A.; Vesselinov, V. V.

2016-12-01

It is desirable to predict the shape of breakthrough curves downgradient of a solute source from subsurface structural parameters (as in the small-perturbation macrodispersion theory) both for realistically heterogeneous fields, and at early time, before any sort of Fickian model is applicable. Using a combination of a priori knowledge, large-scale Monte Carlo simulation, and regression techniques, we have developed closed-form predictive expressions for pre- and post-Fickian flux-weighted solute breakthrough curves as a function of distance from the source (in integral scales) and variance of the log hydraulic conductivity field. Using the ensemble of Monte Carlo realizations, we have simultaneously computed error envelopes for the estimated flux-weighted breakthrough, and for the divergence of point breakthrough curves from the flux-weighted average, as functions of the predictive parameters. We have also obtained implied late-time macrodispersion coefficients for highly heterogeneous environments from the breakthrough statistics. This analysis is relevant for the modelling of reactive as well as conservative transport, since for many kinetic sorption and decay reactions, Laplace-domain modification of the breakthrough curve for conservative solute produces the correct curve for the reactive system.

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.

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).

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).

Regional-scale advective, diffusive, and eruptive dynamics of CO2 and brine leakage through faults and wellbores

NASA Astrophysics Data System (ADS)

Jung, Na-Hyun; Han, Weon Shik; Han, Kyungdoe; Park, Eungyu

2015-05-01

Regional-scale advective, diffusive, and eruptive transport dynamics of CO2 and brine within a natural analogue in the northern Paradox Basin, Utah, were explored by integrating numerical simulations with soil CO2 flux measurements. Deeply sourced CO2 migrates through steeply dipping fault zones to the shallow aquifers predominantly as an aqueous phase. Dense CO2-rich brine mixes with regional groundwater, enhancing CO2 dissolution. Linear stability analysis reveals that CO2 could be dissolved completely within only 500 years. Assigning lower permeability to the fault zones induces fault-parallel movement, feeds up-gradient aquifers with more CO2, and impedes down-gradient fluid flow, developing anticlinal CO2 traps at shallow depths (<300 m). The regional fault permeability that best reproduces field spatial CO2 flux variation is estimated 1 × 10-17 ≤ kh < 1 × 10-16 m2 and 5 × 10-16 ≤ kv < 1 × 10-15 m2. The anticlinal trap serves as an essential fluid source for eruption at Crystal Geyser. Geyser-like discharge sensitively responds to varying well permeability, radius, and CO2 recharge rate. The cyclic behavior of wellbore CO2 leakage decreases with time.

Coupling geophysical investigation with hydrothermal modeling to constrain the enthalpy classification of a potential geothermal resource.

USGS Publications Warehouse

White, Jeremy T.; Karakhanian, Arkadi; Connor, Chuck; Connor, Laura; Hughes, Joseph D.; Malservisi, Rocco; Wetmore, Paul

2015-01-01

An appreciable challenge in volcanology and geothermal resource development is to understand the relationships between volcanic systems and low-enthalpy geothermal resources. The enthalpy of an undeveloped geothermal resource in the Karckar region of Armenia is investigated by coupling geophysical and hydrothermal modeling. The results of 3-dimensional inversion of gravity data provide key inputs into a hydrothermal circulation model of the system and associated hot springs, which is used to evaluate possible geothermal system configurations. Hydraulic and thermal properties are specified using maximum a priori estimates. Limited constraints provided by temperature data collected from an existing down-gradient borehole indicate that the geothermal system can most likely be classified as low-enthalpy and liquid dominated. We find the heat source for the system is likely cooling quartz monzonite intrusions in the shallow subsurface and that meteoric recharge in the pull-apart basin circulates to depth, rises along basin-bounding faults and discharges at the hot springs. While other combinations of subsurface properties and geothermal system configurations may fit the temperature distribution equally well, we demonstrate that the low-enthalpy system is reasonably explained based largely on interpretation of surface geophysical data and relatively simple models.

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.

The Role of Eddies in the General Ocean Circulation: Proceedings of ’Aha Huliko’a Hawaiian Winter Workshop Held at Manoa on January 5-7, 1983

DTIC Science & Technology

1983-01-01

January 5-7, 1983. (SOI iE): Hnai1 Int of Gtnphyqirdt Honohlul. To ORDER THE COMPLETE COMPILATION REPORT USE AD-A137 212 THE COMPONENT PART IS PROVIDED...Holland, 1979). Outside of the region of the wavemaker the vorticity-mixingtheory leads us to expect a down-gradient (southward) component of v’ q...calling them "mesoscale" begins to be marginal. The climatological T4 5 0 field used above is based on cubic spline fits to averages over 2’ (latitude) by

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

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

Freeze, R.A.; McWhorter, D.B.

Many emerging remediation technologies are designed to remove contaminant mass from source zones at DNAPL sites in response to regulatory requirements. There is often concern in the regulated community as to whether mass removal actually reduces risk, or whether the small risk reductions achieved warrant the large costs incurred. This paper sets out a proposed framework for quantifying the degree to which risk is reduced as mass is removed from DNAPL source areas in shallow, saturated, low-permeability media. Risk is defined in terms of meeting an alternate concentration limit (ACL) at a compliance well in an aquifer underlying the sourcemore » zone. The ACL is back-calculated from a carcinogenic health-risk characterization at a downgradient water-supply well. Source-zone mass-removal efficiencies are heavily dependent on the distribution of mass between media (fractures, matrix) and phase (aqueous, sorbed, NAPL). Due to the uncertainties in currently available technology performance data, the scope of the paper is limited to developing a framework for generic technologies rather than making specific risk-reduction calculations for individual technologies. Despite the qualitative nature of the exercise, results imply that very high total mass-removal efficiencies are required to achieve significant long-term risk reduction with technology applications of finite duration. This paper is not an argument for no action at contaminated sites. Rather, it provides support for the conclusions of Cherry et al. (1992) that the primary goal of current remediation should be short-term risk reduction through containment, with the aim to pass on to future generations site conditions that are well-suited to the future applications of emerging technologies with improved mass-removal capabilities.« less

Evaluation of multiple tracer methods to estimate low groundwater flow velocities

DOE PAGES

Reimus, Paul W.; Arnold, Bill W.

2017-02-20

Here, four different tracer methods were used to estimate groundwater flow velocity at a multiple-well site in the saturated alluvium south of Yucca Mountain, Nevada: (1) two single-well tracer tests with different rest or “shut-in” periods, (2) a cross-hole tracer test with an extended flow interruption, (3) a comparison of two tracer decay curves in an injection borehole with and without pumping of a downgradient well, and (4) a natural-gradient tracer test. Such tracer methods are potentially very useful for estimating groundwater velocities when hydraulic gradients are flat (and hence uncertain) and also when water level and hydraulic conductivity datamore » are sparse, both of which were the case at this test location. The purpose of the study was to evaluate the first three methods for their ability to provide reasonable estimates of relatively low groundwater flow velocities in such low-hydraulic-gradient environments. The natural-gradient method is generally considered to be the most robust and direct method, so it was used to provide a “ground truth” velocity estimate. However, this method usually requires several wells, so it is often not practical in systems with large depths to groundwater and correspondingly high well installation costs. The fact that a successful natural gradient test was conducted at the test location offered a unique opportunity to compare the flow velocity estimates obtained by the more easily deployed and lower risk methods with the ground-truth natural-gradient method. The groundwater flow velocity estimates from the four methods agreed very well with each other, suggesting that the first three methods all provided reasonably good estimates of groundwater flow velocity at the site. We discuss the advantages and disadvantages of the different methods, as well as some of the uncertainties associated with them.« less

Evaluation of multiple tracer methods to estimate low groundwater flow velocities

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

Reimus, Paul W.; Arnold, Bill W.

Here, four different tracer methods were used to estimate groundwater flow velocity at a multiple-well site in the saturated alluvium south of Yucca Mountain, Nevada: (1) two single-well tracer tests with different rest or “shut-in” periods, (2) a cross-hole tracer test with an extended flow interruption, (3) a comparison of two tracer decay curves in an injection borehole with and without pumping of a downgradient well, and (4) a natural-gradient tracer test. Such tracer methods are potentially very useful for estimating groundwater velocities when hydraulic gradients are flat (and hence uncertain) and also when water level and hydraulic conductivity datamore » are sparse, both of which were the case at this test location. The purpose of the study was to evaluate the first three methods for their ability to provide reasonable estimates of relatively low groundwater flow velocities in such low-hydraulic-gradient environments. The natural-gradient method is generally considered to be the most robust and direct method, so it was used to provide a “ground truth” velocity estimate. However, this method usually requires several wells, so it is often not practical in systems with large depths to groundwater and correspondingly high well installation costs. The fact that a successful natural gradient test was conducted at the test location offered a unique opportunity to compare the flow velocity estimates obtained by the more easily deployed and lower risk methods with the ground-truth natural-gradient method. The groundwater flow velocity estimates from the four methods agreed very well with each other, suggesting that the first three methods all provided reasonably good estimates of groundwater flow velocity at the site. We discuss the advantages and disadvantages of the different methods, as well as some of the uncertainties associated with them.« less

Model unification and scale-adaptivity in the Eddy-Diffusivity Mass-Flux (EDMF) approach

NASA Astrophysics Data System (ADS)

Neggers, R.; Siebesma, P.

2011-12-01

It has long been understood that the turbulent-convective transport of heat, moisture and momentum plays an important role in the dynamics and climate of the earth's atmosphere. Accordingly, the representation of these processes in General Circulation Models (GCMs) has always been an active research field. Turbulence and convection act on temporal and spatial scales that are unresolved by most present-day GCMs, and have to be represented through parametric relations. Over the years a variety of schemes has been successfully developed. Although differing widely in their details, only two basic transport models stand at the basis of most of these schemes. The first is the diffusive transport model, which can only act down-gradient. An example is the turbulent mixing at small scales. The second is the advective transport model, which can act both down-gradient and counter-gradient. A good example is the transport of heat and moisture by convective updrafts that overshoot into stable layers of air. In practice, diffusive models often make use of a K-profile method or a prognostic TKE budget, while advective models make use of a rising (and entraining) plume budget. While most transport schemes classicaly apply either the diffusive model or advective model, the relatively recently introduced Eddy-Diffusivity Mass-Flux (EDMF) approach aims to combine both techniques. By applying advection and diffusion simultaneously, one can make use of the benefits of both approaches. Since its emergence about a decade ago, the EDMF approach has been successfully applied in both research and operational circulation models. This presentation is dedicated to the EDMF framework. Apart from a short introduction to the EDMF concept and a short overview of its current implementations, our main goal is to elaborate on the opportunities EDMF brings in addressing some long-standing problems in the parameterization of turbulent-convective transport. The first problem is the need for a unified approach in the parameterization of distinct transport regimes. The main objections to a separate representation of regimes are i) artificially discrete regime-transitions, and ii) superfluous and intransparent coding. For a unified approach we need to establish what complexity is sufficient to achieve general applicability. We argue that adding only little complexity already enables the standard EDMF framework to represent multiple boundary-layer transport regimes and smooth transitions between those. The second long-standing problem is that the ever increasing computational capacity and speed has lead to increasingly fine discretizations in GCMs, which requires scale-adaptivity in a sub-grid transport model. It is argued that a flexible partitioning between advection and diffusion within EDMF, as well as the potential to introduce stochastic elements in the advective part of EDMF, creates opportunities to introduce such adaptivity. In the final part of the presentation we will attempt to give an overview of currently ongoing developments of the EDMF framework, both concerning model formulation as well as evaluation efforts of key assumptions against observational datasets and large-eddy simulation results.

Injection of Emulsified Vegetable Oil for Long-Term Bioreduction of Uranium

NASA Astrophysics Data System (ADS)

Brooks, S. C.; Watson, D. B.; Schadt, C. W.; Jardine, P. M.; Gihring, T. M.; Zhang, G.; Mehlhorn, T.; Lowe, K.; Phillips, J.; Earles, J.; Wu, W.; Criddle, C. S.; Kemner, K. M.; Boyanov, M.

2011-12-01

In situ bioremediation of a uranium and nitrate-contaminated aquifer with the slow-release electron donor, emulsified vegetable oil (EVO), was tested at the US DOE Subsurface Biogeochemical Research Program (SBR) Integrated Field Research Challenge (IFRC) site, in Oak Ridge, TN. The EVO injection took place in Area 2 of the IFRC located about 300 m downgradient of the former S-3 disposal ponds. Liquid wastes, disposed in the ponds from 1951 to 1983, were primarily composed of nitric acid, plating wastes containing various metals (Cr, Ni) radionuclides (U, Tc), inorganics (nitrate, sulfate) and organic contaminants (tetrachloroethylene, acetone). Prior pond closure in 1987, large volumes of waste fluids migrated into the subsurface, down Bear Creek Valley and into Bear Creek. Contaminants detected at Area 2 were transported through a high permeability gravelly fill that is considered a preferred transport pathway for U to Bear Creek. Groundwater in the gravelly fill is contaminated with U (1-3 mg/L), sulfate (95-130 mg/L), and nitrate (20-40 mg/L) and 500 mg/kg or higher U has been detected on the solid phase of the fill material. The objective of this study is to investigate the feasibility and long-term sustainability of U(VI) reduction and immobilization, and nitrate degradation in the high permeability, high flow gravel fill using EVO as the electron donor. A one-time EVO injection was conducted over a 2 hour period in the highly permeable gravel (hydraulic conductivity 0.08 cm/sec) in the well instrumented IFRC Area 2 field plot. Extensive monitoring of geochemical parameters, dissolved gases and microbial populations were conducted during the test. A bromide tracer test was conducted prior to the injection of the EVO to assess transport pathways and rates. Geochemical analysis of site groundwater demonstrated the sequential bioreduction of oxygen, nitrate, Mn(IV), Fe(III) and sulfate. Transient accumulation of acetate was observed as an intermediate in the oil degradation. Reduction and removal of U and nitrate from groundwater was observed in all wells in hydraulic connection to the injection wells after 2-4 weeks. U concentrations in groundwater were reduced to below 30 ppb (US EPA drinking water standard) at some well locations and nitrate was reduced to below detectable levels. Rebound of U in groundwater was observed together with the rebound of sulfate concentrations as the EVO was consumed. The flux of U and nitrate contamination from groundwater to the surface water receptor (Bear Creek) was significantly reduced by the EVO injection over a one year period. Uranium (VI) reduction to U(IV) in the field tests was confirmed by X-ray absorption near-edge spectroscopy (XANES) analysis. The reduced U(IV) was determined by X-ray absorption fine structure (XAFS) to be in an Fe-U complex, not uraninite. The activities of major Fe(III)- and sulfate-reducing bacteria with U(VI)-reducing capability as well as methanogens was stimulated after injection of the oil.

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.

In situ bioremediation of uranium with emulsified vegetable oil as the electron donor.

PubMed

Watson, David B; Wu, Wei-Min; Mehlhorn, Tonia; Tang, Guoping; Earles, Jennifer; Lowe, Kenneth; Gihring, Thomas M; Zhang, Gengxin; Phillips, Jana; Boyanov, Maxim I; Spalding, Brian P; Schadt, Christopher; Kemner, Kenneth M; Criddle, Craig S; Jardine, Philip M; Brooks, Scott C

2013-06-18

A field test with a one-time emulsified vegetable oil (EVO) injection was conducted to assess the capacity of EVO to sustain uranium bioreduction in a high-permeability gravel layer with groundwater concentrations of (mM) U, 0.0055; Ca, 2.98; NO3(-), 0.11; HCO3(-), 5.07; and SO4(2-), 1.23. Comparison of bromide and EVO migration and distribution indicated that a majority of the injected EVO was retained in the subsurface from the injection wells to 50 m downgradient. Nitrate, uranium, and sulfate were sequentially removed from the groundwater within 1-2 weeks, accompanied by an increase in acetate, Mn, Fe, and methane concentrations. Due to the slow release and degradation of EVO with time, reducing conditions were sustained for approximately one year, and daily U discharge to a creek, located approximately 50 m from the injection wells, decreased by 80% within 100 days. Total U discharge was reduced by 50% over the one-year period. Reduction of U(VI) to U(IV) was confirmed by synchrotron analysis of recovered aquifer solids. Oxidants (e.g., dissolved oxygen, nitrate) flowing in from upgradient appeared to reoxidize and remobilize uranium after the EVO was exhausted as evidenced by a transient increase of U concentration above ambient values. Occasional (e.g., annual) EVO injection into a permeable Ca and bicarbonate-containing aquifer can sustain uranium bioreduction/immobilization and decrease U migration/discharge.

Selected Natural Attenuation Monitoring Data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, 2007 and 2008

USGS Publications Warehouse

Dinicola, R.S.; Huffman, R.L.

2009-01-01

Previous investigations indicate that natural attenuation and biodegradation of chlorinated volatile organic compounds (VOCs) are substantial in groundwater beneath the 9-acre former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center, Division Keyport, Washington. Phytoremediation combined with on-going natural attenuation processes was the preferred remedy selected by the Navy, as specified in the Record of Decision for the site. The Navy planted two hybrid poplar plantations on the landfill in spring 1999 to remove and to control the migration of chlorinated VOCs in shallow groundwater. The U.S. Geological Survey (USGS) has continued to monitor groundwater geochemistry to ensure that conditions remain favorable for contaminant biodegradation as specified in the Record of Decision. In this report are groundwater geochemical and selected VOC data collected at OU 1 by the USGS during June 18-21, 2007, and June 16-18, 2008, in support of long-term monitoring for natural attenuation. For 2007 and 2008, strongly reducing conditions (sulfate reduction and methanogenesis) most favorable for reductive dechlorination of VOCs were inferred for 9 of 16 upper-aquifer wells and piezometers in the northern and southern phytoremediation plantations. Predominant redox conditions in groundwater from the intermediate aquifer just downgradient from the landfill remained mildly reducing and somewhat favorable for reductive dechlorination of VOCs. Dissolved hydrogen (H2) concentrations measured in the upper aquifer during 2007 and 2008 generally have been lower than H2 concentrations measured before 2002. However, widespread and relatively high methane and sulfide concentrations indicate that the lower H2 concentrations measured do not support a trend from strongly to mildly reducing redox conditions because no widespread changes in groundwater redox conditions were identified that should result in less favorable conditions for the reductive dechlorination of the chlorinated VOCs. For the upper aquifer beneath the northern phytoremediation plantation, chlorinated VOC concentrations in 2007 and 2008 at most piezometers were similar to or slightly less than chlorinated VOC concentrations measured in previous years. The only chlorinated VOC positively detected at piezometers P1-1 and P1-5 was cis-1,2-dichloroethene (cis-DCE); most chlorinated VOC concentrations at piezometer P1-3 were at the lowest levels since monitoring began in 1999. Most VOC concentrations at piezometer P1-4 were similar to VOC concentrations measured in previous years except that vinyl chloride (VC) concentrations inexplicably increased from 280 micrograms per liter (ug/L) in June 2007 to 750 ug/L in June 2008. In 2008, measurement of the sum of concentrations of ethane and ethene, reductive dechlorination byproducts, was at the highest level at most northern plantation wells and piezometers, which is evidence of reductive dechlorination of chlorinated VOCs. For the upper aquifer beneath the southern phytoremediation plantation, chlorinated VOC concentrations in 2007 and 2008 at the piezometers were most often extremely high and they continued to vary considerable over space and between years. At piezometer P1-6, the total chlorinated VOC concentration increased from 380 ug/L in 2007 to more than 20,000 ug/L in 2008. At piezometer P1-7 in 2008, the concentrations of trichloroethene, cis-DCE, and VC were the highest to date, but total chlorinated VOC concentrations at piezometers P1-8, P1-9, and P1-10 in 2008 were relatively low compared to historical levels. The magnitude and persistence of chlorinated VOC concentrations indicate that non-aqueous phase liquid chloroethenes likely are beneath the southern plantation, and the temporal variability in concentrations likely is a result of variations in precipitation and groundwater levels interacting with the non-aqueous phase liquid. The reductive dechlorination byproducts ethane and ethene were detected at

Nitrate addition to groundwater impacted by ethanol-blended fuel accelerates ethanol removal and mitigates the associated metabolic flux dilution and inhibition of BTEX biodegradation

NASA Astrophysics Data System (ADS)

Corseuil, Henry Xavier; Gomez, Diego E.; Schambeck, Cássio Moraes; Ramos, Débora Toledo; Alvarez, Pedro J. J.

2015-03-01

A comparison of two controlled ethanol-blended fuel releases under monitored natural attenuation (MNA) versus nitrate biostimulation (NB) illustrates the potential benefits of augmenting the electron acceptor pool with nitrate to accelerate ethanol removal and thus mitigate its inhibitory effects on BTEX biodegradation. Groundwater concentrations of ethanol and BTEX were measured 2 m downgradient of the source zones. In both field experiments, initial source-zone BTEX concentrations represented less than 5% of the dissolved total organic carbon (TOC) associated with the release, and measurable BTEX degradation occurred only after the ethanol fraction in the multicomponent substrate mixture decreased sharply. However, ethanol removal was faster in the nitrate amended plot (1.4 years) than under natural attenuation conditions (3.0 years), which led to faster BTEX degradation. This reflects, in part, that an abundant substrate (ethanol) can dilute the metabolic flux of target pollutants (BTEX) whose biodegradation rate eventually increases with its relative abundance after ethanol is preferentially consumed. The fate and transport of ethanol and benzene were accurately simulated in both releases using RT3D with our general substrate interaction module (GSIM) that considers metabolic flux dilution. Since source zone benzene concentrations are relatively low compared to those of ethanol (or its degradation byproduct, acetate), our simulations imply that the initial focus of cleanup efforts (after free-product recovery) should be to stimulate the degradation of ethanol (e.g., by nitrate addition) to decrease its fraction in the mixture and speed up BTEX biodegradation.

Nitrate addition to groundwater impacted by ethanol-blended fuel accelerates ethanol removal and mitigates the associated metabolic flux dilution and inhibition of BTEX biodegradation.

PubMed

Corseuil, Henry Xavier; Gomez, Diego E; Schambeck, Cássio Moraes; Ramos, Débora Toledo; Alvarez, Pedro J J

2015-03-01

A comparison of two controlled ethanol-blended fuel releases under monitored natural attenuation (MNA) versus nitrate biostimulation (NB) illustrates the potential benefits of augmenting the electron acceptor pool with nitrate to accelerate ethanol removal and thus mitigate its inhibitory effects on BTEX biodegradation. Groundwater concentrations of ethanol and BTEX were measured 2 m downgradient of the source zones. In both field experiments, initial source-zone BTEX concentrations represented less than 5% of the dissolved total organic carbon (TOC) associated with the release, and measurable BTEX degradation occurred only after the ethanol fraction in the multicomponent substrate mixture decreased sharply. However, ethanol removal was faster in the nitrate amended plot (1.4 years) than under natural attenuation conditions (3.0 years), which led to faster BTEX degradation. This reflects, in part, that an abundant substrate (ethanol) can dilute the metabolic flux of target pollutants (BTEX) whose biodegradation rate eventually increases with its relative abundance after ethanol is preferentially consumed. The fate and transport of ethanol and benzene were accurately simulated in both releases using RT3D with our general substrate interaction module (GSIM) that considers metabolic flux dilution. Since source zone benzene concentrations are relatively low compared to those of ethanol (or its degradation byproduct, acetate), our simulations imply that the initial focus of cleanup efforts (after free-product recovery) should be to stimulate the degradation of ethanol (e.g., by nitrate addition) to decrease its fraction in the mixture and speed up BTEX biodegradation. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

Hydraulic characterization of volcanic rocks in Pahute Mesa using an integrated analysis of 16 multiple-well aquifer tests, Nevada National Security Site, 2009–14

USGS Publications Warehouse

Garcia, C. Amanda; Jackson, Tracie R.; Halford, Keith J.; Sweetkind, Donald S.; Damar, Nancy A.; Fenelon, Joseph M.; Reiner, Steven R.

2017-01-20

An improved understanding of groundwater flow and radionuclide migration downgradient from underground nuclear-testing areas at Pahute Mesa, Nevada National Security Site, requires accurate subsurface hydraulic characterization. To improve conceptual models of flow and transport in the complex hydrogeologic system beneath Pahute Mesa, the U.S. Geological Survey characterized bulk hydraulic properties of volcanic rocks using an integrated analysis of 16 multiple-well aquifer tests. Single-well aquifer-test analyses provided transmissivity estimates at pumped wells. Transmissivity estimates ranged from less than 1 to about 100,000 square feet per day in Pahute Mesa and the vicinity. Drawdown from multiple-well aquifer testing was estimated and distinguished from natural fluctuations in more than 200 pumping and observation wells using analytical water-level models. Drawdown was detected at distances greater than 3 miles from pumping wells and propagated across hydrostratigraphic units and major structures, indicating that neither faults nor structural blocks noticeably impede or divert groundwater flow in the study area.Consistent hydraulic properties were estimated by simultaneously interpreting drawdown from the 16 multiple-well aquifer tests with an integrated groundwater-flow model composed of 11 well-site models—1 for each aquifer test site. Hydraulic properties were distributed across volcanic rocks with the Phase II Pahute Mesa-Oasis Valley Hydrostratigraphic Framework Model. Estimated hydraulic-conductivity distributions spanned more than two orders of magnitude in hydrostratigraphic units. Overlapping hydraulic conductivity ranges among units indicated that most Phase II Hydrostratigraphic Framework Model units were not hydraulically distinct. Simulated total transmissivity ranged from 1,600 to 68,000 square feet per day for all pumping wells analyzed. High-transmissivity zones exceeding 10,000 square feet per day exist near caldera margins and extend along the northern and eastern Pahute Mesa study area and near the southwestern edge of the study area. The estimated hydraulic-property distributions and observed hydraulic connections among geologic structures improved the characterization and representation of groundwater flow at Pahute Mesa.

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.

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

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.

Developing Conceptual Models of Biodegradation: Lessons Learned From a Long-Term Study of a Crude-Oil Contaminant Plume

NASA Astrophysics Data System (ADS)

Cozzarelli, I. M.; Esaid, H. I.; Bekins, B. A.; Eganhouse, R. P.; Baedecker, M.

2002-05-01

Assessment of natural attenuation as a remedial option requires understanding the long-term fate of contaminant compounds. The development of correct conceptual models of biodegradation requires observations at spatial and temporal scales appropriate for the reactions being measured. For example, the availability of electron acceptors such as solid-phase iron oxides may vary at the cm scale due to aquifer heterogeneities. Characterizing the distribution of these oxides may require small-scale measurements over time scales of tens of years in order to assess their impact on the fate of contaminants. The long-term study of natural attenuation of hydrocarbons in a contaminant plume near Bemidji, MN provides insight into how natural attenuation of hydrocarbons evolves over time. The sandy glacial-outwash aquifer at this USGS Toxic Substances Hydrology research site was contaminated by crude oil in 1979. During the 16 years that data have been collected the shape and extent of the contaminant plume changed as redox reactions, most notably iron reduction, progressed over time. Investigation of the controlling microbial reactions in this system required a systematic and multi-scaled approach. Early indications of plume shrinkage were observed over a time scale of a few years, based on observation well data. These changes were associated with iron reduction near the crude-oil source. The depletion of Fe (III) oxides near the contaminant source caused the dissolved iron concentrations to increase and spread downgradient at a rate of approximately 3 m/year. The zone of maximum benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations has also spread within the anoxic plume. Subsequent analyses of sediment and water, collected at small-scale cm intervals from cores in the contaminant plume, provided insight into the evolution of redox zones at smaller scales. Contaminants, such as ortho-xylene, that appeared to be contained near the oil source based on the larger-scale observation well data, were observed to be migrating in thin layers as the aquifer evolved to methanogenic conditions in narrow zones. The impact of adequately identifying the microbially mediated redox reactions was illustrated with a novel inverse modeling effort (using both the USGS solute transport and biodegradation code BIOMOC and the USGS universal inverse modeling code UCODE) to quantify field-scale hydrocarbon dissolution and biodegradation at the Bemidji site. Extensive historical data compiled at the Bemidji site were used, including 1352 concentration observations from 30 wells and 66 core sections. The simulations reproduced the general large-scale evolution of the plume, but the percent BTEX mass removed from the oil body after 18 years varied significantly, depending on which biodegradation conceptual model was used. The best fit was obtained for the iron-reduction conceptual model, which incorporated the finite availability of Fe (III) in the aquifer and reproduced the field observation that depletion of solid-phase iron resulted in increased downgradient transport of BTEX compounds. The predicted benzene plume 50 years after the spill showed significantly higher concentrations of benzene for the iron-reduction model compared to other conceptual models tested. This study demonstrates that the long-term sustainability of the electron acceptors is key to predicting the ultimate fate of the hydrocarbons. Assessing this evolution of redox processes and developing an adequate conceptual model required observations on multiple spatial scales over the course of many years.

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.

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.

Denitrification and dilution along fracture flowpaths influence the recovery of a bedrock aquifer from nitrate contamination.

PubMed

Kim, Jonathan J; Comstock, Jeff; Ryan, Peter; Heindel, Craig; Koenigsberger, Stephan

2016-11-01

In 2000, elevated nitrate concentrations ranging from 12 to 34mg/L NO3N were discovered in groundwater from numerous domestic bedrock wells adjacent to a large dairy farm in central Vermont. Long-term plots and contours of nitrate vs. time for bedrock wells showed "little/no", "moderate", and "large" change patterns that were spatially separable. The metasedimentary bedrock aquifer is strongly anisotropic and groundwater flow is controlled by fractures, bedding/foliation, and basins and ridges in the bedrock surface. Integration of the nitrate concentration vs. time data and the physical and chemical aquifer characterization suggest two nitrate sources: a point source emanating from a waste ravine and a non-point source that encompasses the surrounding fields. Once removed, the point source of NO3 (manure deposited in a ravine) was exhausted and NO3 dropped from 34mg/L to <10mg/L after ~10years; however, persistence of NO3 in the 3 to 8mg/L range (background) reflects the long term flux of nitrates from nutrients applied to the farm fields surrounding the ravine over the years predating and including this study. Inferred groundwater flow rates from the waste ravine to either moderate change wells in basin 2 or to the shallow bedrock zone beneath the large change wells are 0.05m/day, well within published bedrock aquifer flow rates. Enrichment of (15)N and (18)O in nitrate is consistent with lithotrophic denitrification of NO3 in the presence of dissolved Mn and Fe. Once the ravine point-source was removed, denitrification and dilution collectively were responsible for the down-gradient decrease of nitrate in this bedrock aquifer. Denitrification was most influential when NO3N was >10mg/L. Our multidisciplinary methods of aquifer characterization are applicable to groundwater contamination in any complexly-deformed and metamorphosed bedrock aquifer. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

Concentration-Discharge Relations in the Critical Zone: Implications for Resolving Critical Zone Structure, Function, and Evolution

NASA Astrophysics Data System (ADS)

Chorover, Jon; Derry, Louis A.; McDowell, William H.

2017-11-01

Critical zone science seeks to develop mechanistic theories that describe critical zone structure, function, and long-term evolution. One postulate is that hydrogeochemical controls on critical zone evolution can be inferred from solute discharges measured down-gradient of reactive flow paths. These flow paths have variable lengths, interfacial compositions, and residence times, and their mixing is reflected in concentration-discharge (C-Q) relations. Motivation for this special section originates from a U.S. Critical Zone Observatories workshop that was held at the University of New Hampshire, 20-22 July 2015. The workshop focused on resolving mechanistic CZ controls over surface water chemical dynamics across the full range of lithogenic (e.g., nonhydrolyzing and hydrolyzing cations and oxyanions) and bioactive solutes (e.g., organic and inorganic forms of C, N, P, and S), including dissolved and colloidal species that may cooccur for a given element. Papers submitted to this special section on "concentration-discharge relations in the critical zone" include those from authors who attended the workshop, as well as others who responded to the open solicitation. Submissions were invited that utilized information pertaining to internal, integrated catchment function (relations between hydrology, biogeochemistry, and landscape structure) to help illuminate controls on observed C-Q relations.

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)

Effect of treated-sewage contamination upon bacterial energy charge, adenine nucleotides, and DNA content in a sandy aquifer on cape cod

USGS Publications Warehouse

Metge, D.W.; Brooks, M.H.; Smith, R.L.; Harvey, R.W.

1993-01-01

Changes in adenylate energy charge (EC(A)) and in total adenine nucleotides (A(T)) and DNA content (both normalized to the abundance of free- living, groundwater bacteria) in response to carbon loading were determined for a laboratory-grown culture and for a contaminated aquifer. The latter study involved a 3-km-long transect through a contaminant plume resulting from continued on-land discharge of secondary sewage to a shallow, sandy aquifer on Cape Cod, Mass. With the exception of the most contaminated groundwater immediately downgradient from the contaminant source, DNA and adenylate levels correlated strongly with bacterial abundance and decreased exponentially with increasing distance downgradient. EC(A)s (0.53 to 0.60) and the ratios of ATP to DNA (0.001 to 0.003) were consistently low, suggesting that the unattached bacteria in this groundwater study are metabolically stressed, despite any eutrophication that might have occurred. Elevated EC(A)s (up to 0.74) were observed in glucose-amended groundwater, confirming that the metabolic state of this microbial community could be altered. In general, per-bacterium DNA and ATP contents were approximately twofold higher in the plume than in surrounding groundwater, although EC(A) and per-bacterium levels of A(T) differed little in the plume and the surrounding uncontaminated groundwater. However, per-bacterium levels of DNA and A(T) varied six- and threefold, respectively, during a 6-h period of decreasing growth rate for an unidentified pseudomonad isolated from contaminated groundwater and grown in batch culture. These data suggest that the DNA content of groundwater bacteria may be more sensitive than their A(T) to the degree of carbon loading, which may have significant ramifications in the use of nucleic acids and adenine nucleotides for estimating the metabolic status of bacterial communities within more highly contaminated aquifers.

Modeling the influence of coupled mass transfer processes on mass flux downgradient of heterogeneous DNAPL source zones

NASA Astrophysics Data System (ADS)

Yang, Lurong; Wang, Xinyu; Mendoza-Sanchez, Itza; Abriola, Linda M.

2018-04-01

Sequestered mass in low permeability zones has been increasingly recognized as an important source of organic chemical contamination that acts to sustain downgradient plume concentrations above regulated levels. However, few modeling studies have investigated the influence of this sequestered mass and associated (coupled) mass transfer processes on plume persistence in complex dense nonaqueous phase liquid (DNAPL) source zones. This paper employs a multiphase flow and transport simulator (a modified version of the modular transport simulator MT3DMS) to explore the two- and three-dimensional evolution of source zone mass distribution and near-source plume persistence for two ensembles of highly heterogeneous DNAPL source zone realizations. Simulations reveal the strong influence of subsurface heterogeneity on the complexity of DNAPL and sequestered (immobile/sorbed) mass distribution. Small zones of entrapped DNAPL are shown to serve as a persistent source of low concentration plumes, difficult to distinguish from other (sorbed and immobile dissolved) sequestered mass sources. Results suggest that the presence of DNAPL tends to control plume longevity in the near-source area; for the examined scenarios, a substantial fraction (43.3-99.2%) of plume life was sustained by DNAPL dissolution processes. The presence of sorptive media and the extent of sorption non-ideality are shown to greatly affect predictions of near-source plume persistence following DNAPL depletion, with plume persistence varying one to two orders of magnitude with the selected sorption model. Results demonstrate the importance of sorption-controlled back diffusion from low permeability zones and reveal the importance of selecting the appropriate sorption model for accurate prediction of plume longevity. Large discrepancies for both DNAPL depletion time and plume longevity were observed between 2-D and 3-D model simulations. Differences between 2- and 3-D predictions increased in the presence of sorption, especially for the case of non-ideal sorption, demonstrating the limitations of employing 2-D predictions for field-scale modeling.

Identification of abiotic and biotic reductive dechlorination in a chlorinated ethene plume after thermal source remediation by means of isotopic and molecular biology tools

NASA Astrophysics Data System (ADS)

Badin, Alice; Broholm, Mette M.; Jacobsen, Carsten S.; Palau, Jordi; Dennis, Philip; Hunkeler, Daniel

2016-09-01

Thermal tetrachloroethene (PCE) remediation by steam injection in a sandy aquifer led to the release of dissolved organic carbon (DOC) from aquifer sediments resulting in more reduced redox conditions, accelerated PCE biodegradation, and changes in microbial populations. These changes were documented by comparing data collected prior to the remediation event and eight years later. Based on the premise that dual C-Cl isotope slopes reflect ongoing degradation pathways, the slopes associated with PCE and TCE suggest the predominance of biotic reductive dechlorination near the source area. PCE was the predominant chlorinated ethene near the source area prior to thermal treatment. After thermal treatment, cDCE became predominant. The biotic contribution to these changes was supported by the presence of Dehalococcoides sp. DNA (Dhc) and Dhc targeted rRNA close to the source area. In contrast, dual C-Cl isotope analysis together with the almost absent VC 13C depletion in comparison to cDCE 13C depletion suggested that cDCE was subject to abiotic degradation due to the presence of pyrite, possible surface-bound iron (II) or reduced iron sulphides in the downgradient part of the plume. This interpretation is supported by the relative lack of Dhc in the downgradient part of the plume. The results of this study show that thermal remediation can enhance the biodegradation of chlorinated ethenes, and that this effect can be traced to the mobilisation of DOC due to steam injection. This, in turn, results in more reduced redox conditions which favor active reductive dechlorination and/or may lead to a series of redox reactions which may consecutively trigger biotically induced abiotic degradation. Finally, this study illustrates the valuable complementary application of compound-specific isotopic analysis combined with molecular biology tools to evaluate which biogeochemical processes are taking place in an aquifer contaminated with chlorinated ethenes.

Monitoring the evolution and migration of a methane gas plume in an unconfined sandy aquifer using time-lapse GPR and ERT.

PubMed

Steelman, Colby M; Klazinga, Dylan R; Cahill, Aaron G; Endres, Anthony L; Parker, Beth L

2017-10-01

Fugitive methane (CH 4 ) leakage associated with conventional and unconventional petroleum development (e.g., shale gas) may pose significant risks to shallow groundwater. While the potential threat of stray (CH 4 ) gas in aquifers has been acknowledged, few studies have examined the nature of its migration and fate in a shallow groundwater flow system. This study examines the geophysical responses observed from surface during a 72day field-scale simulated CH 4 leak in an unconfined sandy aquifer at Canadian Forces Base Borden, Canada, to better understand the transient behaviour of fugitive CH 4 gas in the subsurface. Time-lapse ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) were used to monitor the distribution and migration of the gas-phase and assess any impacts to groundwater hydrochemistry. Geophysical measurements captured the transient formation of a CH 4 gas plume emanating from the injector, which was accompanied by an increase in total dissolved gas pressure (P TDG ). Subsequent reductions in P TDG were accompanied by reduced bulk resistivity around the injector along with an increase in the GPR reflectivity along horizontal bedding reflectors farther downgradient. Repeat temporal GPR reflection profiling identified three events with major peaks in reflectivity, interpreted to represent episodic lateral CH 4 gas release events into the aquifer. Here, a gradual increase in P TDG near the injector caused a sudden lateral breakthrough of gas in the direction of groundwater flow, causing free-phase CH 4 to migrate much farther than anticipated based on groundwater advection. CH 4 accumulated along subtle permeability boundaries demarcated by grain-scale bedding within the aquifer characteristic of numerous Borden-aquifer multi-phase flow experiments. Diminishing reflectivity over a period of days to weeks suggests buoyancy-driven migration to the vadose zone and/or CH 4 dissolution into groundwater. Lateral and vertical CH 4 migration was primarily governed by subtle, yet measurable heterogeneity and anisotropy in the aquifer. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Evolutionary algorithms for the optimization of advective control of contaminated aquifer zones

NASA Astrophysics Data System (ADS)

Bayer, Peter; Finkel, Michael

2004-06-01

Simple genetic algorithms (SGAs) and derandomized evolution strategies (DESs) are employed to adapt well capture zones for the hydraulic optimization of pump-and-treat systems. A hypothetical contaminant site in a heterogeneous aquifer serves as an application template. On the basis of the results from numerical flow modeling, particle tracking is applied to delineate the pathways of the contaminants. The objective is to find the minimum pumping rate of up to eight recharge wells within a downgradient well placement area. Both the well coordinates and the pumping rates are subject to optimization, leading to a mixed discrete-continuous problem. This article discusses the ideal formulation of the objective function for which the number of particles and the total pumping rate are used as decision criteria. Boundary updating is introduced, which enables the reorganization of the decision space limits by the incorporation of experience from previous optimization runs. Throughout the study the algorithms' capabilities are evaluated in terms of the number of model runs which are needed to identify optimal and suboptimal solutions. Despite the complexity of the problem both evolutionary algorithm variants prove to be suitable for finding suboptimal solutions. The DES with weighted recombination reveals to be the ideal algorithm to find optimal solutions. Though it works with real-coded decision parameters, it proves to be suitable for adjusting discrete well positions. Principally, the representation of well positions as binary strings in the SGA is ideal. However, even if the SGA takes advantage of bookkeeping, the vital high discretization of pumping rates results in long binary strings, which escalates the model runs that are needed to find an optimal solution. Since the SGA string lengths increase with the number of wells, the DES gains superiority, particularly for an increasing number of wells. As the DES is a self-adaptive algorithm, it proves to be the more robust optimization method for the selected advective control problem than the SGA variants of this study, exhibiting a less stochastic search which is reflected in the minor variability of the found solutions.

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.

Contributing recharge areas, groundwater travel time, and groundwater water quality of the Missouri River alluvial aquifer near the City of Independence, Missouri, well field, 1997-2008

USGS Publications Warehouse

Kelly, Brian P.

2011-01-01

The City of Independence, Missouri, operates a well field in the Missouri River alluvial aquifer. Contributing recharge areas (CRA) were last determined for the well field in 1996. Since that time, eight supply wells have been installed in the area north of the Missouri River and well pumpage has changed for the older supply wells. The change in pumping has altered groundwater flow and substantially changed the character of the CRA and groundwater travel times to the supply wells. The U.S Geological Survey, in a cooperative study with the City of Independence, Missouri, simulated steady-state groundwater flow for 2007 well pumpage, average annual river stage, and average annual recharge. Particle-tracking analysis was used to determine the CRA for supply wells and monitoring wells, and the travel time from recharge areas to supply wells, recharge areas to monitoring wells, and monitoring wells to supply wells. The simulated CRA for the well field is elongated in the upstream direction and extends to both sides of the Missouri River. Groundwater flow paths and recharge areas estimated for monitoring wells indicate the origin of water to each monitoring well, the travel time of that water from the recharge area, the flow path from the vicinity of each monitoring well to a supply well, and the travel time from the monitoring well to the supply well. Monitoring wells 14a and 14b have the shortest groundwater travel time from their contributing recharge area of 0.30 years and monitoring well 29a has the longest maximum groundwater travel time from its contributing recharge area of 1,701 years. Monitoring well 22a has the shortest groundwater travel time of 0.5 day to supply well 44 and monitoring well 3b has the longest maximum travel time of 31.91 years to supply well 10. Water-quality samples from the Independence groundwater monitoring well network were collected from 1997 to 2008 by USGS personnel during ongoing annual sampling within the 10-year contributing recharge area (CRA) of the Independence well field. Statistical summaries and the spatial and temporal variability of water quality in the Missouri River alluvial aquifer near the Independence well field were characterized from analyses of 598 water samples. Water-quality constituent groups include dissolved oxygen and physical properties, nutrients, major ions and trace elements, wastewater indicator compounds, fuel compounds, and total benzene, toluene, ethylbenzene, and xylene (BTEX), alachlor, and atrazine. The Missouri Secondary Maximum Contaminant Level (SMCL) for iron was exceeded in almost all monitoring wells. The Missouri Maximum Contaminant Level (MCL) for arsenic was exceeded 32 times in samples from monitoring wells. The MCL for barium was exceeded five times in samples from one monitoring well. The SMCL for manganese was exceeded 160 times in samples from all monitoring wells and the combined well-field sample. The most frequently detected wastewater indicator compounds were N,N-diethyl-meta-toluamide (DEET), phenol, caffeine, and metolachlor. The most frequently detected fuel compounds were toluene and benzene. Alachlor was detected in 22 samples and atrazine was detected in 37 samples and the combined well-field sample. The MCL for atrazine was exceeded in one sample from one monitoring well. Samples from monitoring wells with median concentrations of total inorganic nitrogen larger than 1 milligram per liter (mg/L) are located near agricultural land and may indicate that agricultural land practices are the source of nitrogen to groundwater. Largest median values of specific conductance; total inorganic nitrogen; dissolved calcium, magnesium, sodium, iron, arsenic, manganese, bicarbonate, and sulfate and detections of wastewater indicator compounds generally were in water samples from monitoring wells with CRAs that intersect the south bank of the Missouri River. Zones of higher specific conductance were located just upstream from the Independen

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.

Field-Scale Hydraulic Conductivity (K) and Mass Transfer at the MADE Site in Columbus, Mississippi: A Review and Continuing Studies

NASA Astrophysics Data System (ADS)

Molz, F. J.; Guan, J.; Liu, H.; Zheng, C.

2005-12-01

During the late eighties and early nineties, several natural gradient tracer tests were conducted in a shallow unconfined fluvial aquifer at Columbus Air Force Base in Mississippi. The aquifer matrix was highly heterogeneous (natural log(K) variance of about 4.5) and consisted of poorly-sorted to well-sorted layered sandy gravel to gravely sand, with variable silt and clay content (Boggs et al., 1993). Prior to performing the tracer tests, the aquifer was characterized extensively using a borehole flow-meter. The resulting tracer plumes were highly elongated with dilute leading edges in the down-gradient direction, and transport appeared to be advection-dominated. Although there is still some controversy, reasonably successful simulations of the MADE tracer data have settled on an approximate dual porosity conceptualization of the aquifer matrix. Throughout the aquifer, high K zones (mobile porosity) are visualized as being in contact with low K zones (immobile porosity), with mass transfer between the zones governed by an effective mass transfer coefficient B. Such a transfer coefficient is analogous to the matrix diffusion coefficient Dm used to simulate transport in fractured rock with diffusion into the rock matrix (Foster, 1975). Recently, experiments and geometrically-based reasoning have been presented, implying that the effective Dm, like dispersivity, increases with travel distance (Liu et al., 2004; Zhou et al., 2005). Conversely, other studies based on multiple rate mass transfer between mobile and immobile porosities in granular media (Haggerty et al., 2004) have indicated that B will decrease with travel distance. Thus in geometrically complex granular media, like those at the MADE site, two opposing effects may be present. To further study this question, new 3-D simulations of tritium transport are being performed using flow-meter K data and the measured tritium concentrations at selected times. Results to date indicate that B generally decreases with scale, but changes will depend on the details of how the flow and mass transfer process at the MADE site is conceptualized. For example, did the tritium tracer injected initially all enter the mobile porosity, as commonly assumed, or was a significant portion of it forced into the immobile porosity? Was fluid in the immobile porosity essentially non-moving relative to mobile fluid, or did both fluid classes move significantly down-gradient. Alternatively, was tracer simply injected into an overall low K region, from which it slowly leaked out during the course of the 328 day experiment? Simulation results from different scenarios will be presented and implications discussed concerning the detailed scale-dependence of B at the MADE Site.

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

Superfund record of decision (EPA Region 1): Peterson/Puritan Site, Operable Unit 1, Cumberland/Lincoln, RI, September 1993

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

Not Available

1993-09-01

This Decision Document presents the selected remedial action for the Peterson/Puritan, Inc. Superfund Site, Operable Unit 1, in Cumberland and Lincoln, Rhode Island. Operable Unit 1 contains two remediation areas. The CCL remediation area, a source of volatile organic contamination, includes the former Peterson/Puritan, Inc. facility, which is the Site's namesake (currently the CCL Custom Manufacturing facility, and referred to as CCL). The PAC remediation area includes the Pacific Anchor Chemical Corporation (PAC ) facility (formerly the Lonza and Universal Chemical Company facility), which is a source of arsenic and volatile organic contamination. Each remediation area is further split intomore » source and downgradient area components, respectively.« less

Monitoring well utility in a heterogeneous DNAPL source zone area: Insights from proximal multilevel sampler wells and sampling capture-zone modelling

NASA Astrophysics Data System (ADS)

McMillan, Lindsay A.; Rivett, Michael O.; Wealthall, Gary P.; Zeeb, Peter; Dumble, Peter

2018-03-01

Groundwater-quality assessment at contaminated sites often involves the use of short-screen (1.5 to 3 m) monitoring wells. However, even over these intervals considerable variation may occur in contaminant concentrations in groundwater adjacent to the well screen. This is especially true in heterogeneous dense non-aqueous phase liquid (DNAPL) source zones, where cm-scale contamination variability may call into question the effectiveness of monitoring wells to deliver representative data. The utility of monitoring wells in such settings is evaluated by reference to high-resolution multilevel sampler (MLS) wells located proximally to short-screen wells, together with sampling capture-zone modelling to explore controls upon well sample provenance and sensitivity to monitoring protocols. Field data are analysed from the highly instrumented SABRE research site that contained an old trichloroethene source zone within a shallow alluvial aquifer at a UK industrial facility. With increased purging, monitoring-well samples tend to a flow-weighted average concentration but may exhibit sensitivity to the implemented protocol and degree of purging. Formation heterogeneity adjacent to the well-screen particularly, alongside pump-intake position and water level, influence this sensitivity. Purging of low volumes is vulnerable to poor reproducibility arising from concentration variability predicted over the initial 1 to 2 screen volumes purged. Marked heterogeneity may also result in limited long-term sample concentration stabilization. Development of bespoke monitoring protocols, that consider screen volumes purged, alongside water-quality indicator parameter stabilization, is recommended to validate and reduce uncertainty when interpreting monitoring-well data within source zone areas. Generalised recommendations on monitoring well based protocols are also developed. A key monitoring well utility is their proportionately greater sample draw from permeable horizons constituting a significant contaminant flux pathway and hence representative fraction of source mass flux. Acquisition of complementary, high-resolution, site monitoring data, however, vitally underpins optimal interpretation of monitoring-well datasets and appropriate advancement of a site conceptual model and remedial implementation.

Environmental Protection Department's well inventory through the second quarter of 1992

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

Rogers, C.D.

This report is an inventory of the wells recorded in Environmental Protection Department/Environmental Monitoring Section (EPD/EMS) documents since the startup of the Savannah River Site (SRS) and includes wells monitored by special request and SRS research wells. Wells listed in this inventory are monitoring wells unless otherwise indicated. The purpose of this report is as follows: to provide a historical record of the wells that EPD/EMS has monitored, to provide a document containing a list of wells that are currently in the EPD/EMS Groundwater Monitoring Program, and to provide pertinent information about all wells listed in EPD/EMS documents.

Environmental Protection Department`s well inventory through the second quarter of 1992

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

Rogers, C.D.

This report is an inventory of the wells recorded in Environmental Protection Department/Environmental Monitoring Section (EPD/EMS) documents since the startup of the Savannah River Site (SRS) and includes wells monitored by special request and SRS research wells. Wells listed in this inventory are monitoring wells unless otherwise indicated. The purpose of this report is as follows: to provide a historical record of the wells that EPD/EMS has monitored, to provide a document containing a list of wells that are currently in the EPD/EMS Groundwater Monitoring Program, and to provide pertinent information about all wells listed in EPD/EMS documents.

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.

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.

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.

Natural Attenuation-Untersuchungen "ehemalige Abfalldeponie Osterhofen"

NASA Astrophysics Data System (ADS)

Rügner, Hermann; Holder, Thomas; Maier, Uli; Bayer-Raich, Marti; Grathwohl, Peter; Teutsch, Georg

Kurzfassung Im Abstrom der "ehemaligen Abfalldeponie Osterhofen" wurden Konzentrationen an Ammonium festgestellt, die deutlich über dem in Baden-Württemberg geltenden Prüfwert liegen. Im Rahmen detaillierter Natural Attenuation (NA) Untersuchungen wurde überprüft, inwieweit die Nutzung mikrobiologischer Abbau- und Rückhalteprozesse des Ammoniums eine geeignete Entscheidungsoption für den Standort darstellt. Das Ergebnis der hierbei im Wesentlichen durchgeführten Frachtbestimmungen (mittels Immissionspumpversuchen) sowie einer konzeptionellen numerischen Modellierung des Ammoniumabbaues am Standort war, dass ein mikrobiologischer Abbau des Ammoniums zu Nitrat stattfindet (70-85 % Abbau innerhalb einer Distanz von ca. 450 m), dass allerdings aufgrund der diffusiv-/dispersiv bedingten langsamen Zufuhr von Sauerstoff in die Abstromfahne ein insgesamt ca. 550-680 m langer, stationärer Reaktionsraum existiert. Eine Gefahr für das Grundwasser im weiteren Abstrom der Deponie konnte ausgeschlossen werden. Eine gezielte Überwachung der NA-Prozesse kann am Standort an die Stelle einer aktiven Sanierungsmaßnahme treten. In groundwater downgradient of the former municipal landfill site ``Osterhofen'' concentrations of Ammonium much above the legal limit were detected. Based on detailed site investigations it was evaluated whether natural attenuation (NA) may be used as a contaminated land management option at the site. Investigations were mainly based on the determination of contaminant mass flow rates (by integral pumping tests) and numerical conceptual modelling of the ammonium degradation. As result it was found that biodegradation of ammonium is very effective (70-85 % degradation within a distance of approx. 450 m). Because oxygen supply into the plume is limited by transverse mixing a steady state plume of approx. 550-680 m in length exists. Since beyond this reactive zone no further risk for groundwater arises, monitored natural attenuation (MNA) is an appropriate contaminated land management option at the site.

In situ lifetimes and kinetics of a reductive whey barrier and an oxidative ORC barrier in the subsurface.

PubMed

Barcelona, M J; Xie, G

2001-08-15

Permeable reactive barriers (PRB) are being used to engineer favorable field conditions for in-situ remediation efforts. Two redox adjustment barriers were installed to facilitate a 10-month research effort on the fate and transport of MTBE (methyl tert-butyl ether) at a site called the Michigan Integrated Remediation Technology Laboratory (MIRTL). Thirty kilograms of whey were injected as a slurry into an unconfined aquifer to establish an upgradient reductive zone to reduce O2 concentration in the vicinity of a contaminant injection source. To minimize the impact of contaminant release, 363 kg of oxygen release compound (ORC) were placed in the aquifer as a downgradient oxidative barrier. Dissolved oxygen and other chemical species were monitored in the field to evaluate the effectiveness of this technology. A transient one-dimensional advective-dispersive-reaction (ADR) model was proposed to simulate the dissolved oxygen transport. The equations were solved with commonly encountered PRB initial and constant/variable boundary conditions. No similar previous solution was found in the literature. The in-situ lifetimes, based on variable source loading, were estimated to be 1,661 and 514 days for the whey barrier and ORC barrier, respectively. Estimates based on either maximum O2 consumption/production or measured O2 curves were found to under- or overestimate the lifetime of the barriers. The pseudo-first-order rate constant of whey depletion was estimated to be 0.303/d with a dissolution rate of 0.04/d. The oxygen release rate constant in the ORC barrier was estimated to be 0.03/d. This paper provides a means to design and predict the performance of reactive redox barriers, especially when only limited field data are available.

Perspectives on Wellness Self-Monitoring Tools for Older Adults

PubMed Central

Huh, Jina; Le, Thai; Reeder, Blaine; Thompson, Hilaire J.; Demiris, George

2013-01-01

Purpose Our purpose was to understand different stakeholder perceptions about the use of self-monitoring tools, specifically in the area of older adults’ personal wellness. In conjunction with the advent of personal health records, tracking personal health using self-monitoring technologies shows promising patient support opportunities. While clinicians’ tools for monitoring of older adults have been explored, we know little about how older adults may self-monitor their wellness and health and how their health care providers would perceive such use. Methods We conducted three focus groups with health care providers (n=10) and four focus groups with community-dwelling older adults (n=31). Results Older adult participants’ found the concept of self-monitoring unfamiliar and this influenced a narrowed interest in the use of wellness self-monitoring tools. On the other hand, health care provider participants showed open attitudes towards wellness monitoring tools for older adults and brainstormed about various stakeholders’ use cases. The two participant groups showed diverging perceptions in terms of: perceived uses, stakeholder interests, information ownership and control, and sharing of wellness monitoring tools. Conclusions Our paper provides implications and solutions for how older adults’ wellness self-monitoring tools can enhance patient-health care provider interaction, patient education, and improvement in overall wellness. PMID:24041452

Perspectives on wellness self-monitoring tools for older adults.

PubMed

Huh, Jina; Le, Thai; Reeder, Blaine; Thompson, Hilaire J; Demiris, George

2013-11-01

Our purpose was to understand different stakeholder perceptions about the use of self-monitoring tools, specifically in the area of older adults' personal wellness. In conjunction with the advent of personal health records, tracking personal health using self-monitoring technologies shows promising patient support opportunities. While clinicians' tools for monitoring of older adults have been explored, we know little about how older adults may self-monitor their wellness and health and how their health care providers would perceive such use. We conducted three focus groups with health care providers (n=10) and four focus groups with community-dwelling older adults (n=31). Older adult participants' found the concept of self-monitoring unfamiliar and this influenced a narrowed interest in the use of wellness self-monitoring tools. On the other hand, health care provider participants showed open attitudes toward wellness monitoring tools for older adults and brainstormed about various stakeholders' use cases. The two participant groups showed diverging perceptions in terms of: perceived uses, stakeholder interests, information ownership and control, and sharing of wellness monitoring tools. Our paper provides implications and solutions for how older adults' wellness self-monitoring tools can enhance patient-health care provider interaction, patient education, and improvement in overall wellness. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Characterization of an alluvial aquifer with thermal tracer tomography

NASA Astrophysics Data System (ADS)

Somogyvári, Márk; Bayer, Peter

2017-04-01

In the summer of 2015, a series of thermal tracer tests was performed at the Widen field site in northeast Switzerland. At this site numerous hydraulic, tracer, geophysical and hydrogeophysical field tests have been conducted in the past to investigate a shallow alluvial aquifer. The goals of the campaign in 2015 were to design a cost-effective thermal tracer tomography setup and to validate the concept of travel time-based thermal tracer tomography under field conditions. Thermal tracer tomography uses repeated thermal tracer injections with different injection depths and distributed temperature measurements to map the hydraulic conductivity distribution of a heterogeneous aquifer. The tracer application was designed with minimal experimental time and cost. Water was heated in inflatable swimming pools using direct sunlight of the warm summer days, and it was injected as low temperature pulses in a well. Because of the small amount of injected heat, no long recovery times were required between the repeated heat tracer injections and every test started from natural thermal conditions. At Widen, four thermal tracer tests were performed during a period of three days. Temperatures were measured in one downgradient well using a distributed temperature measurement system installed at seven depth points. Totally 12 temperature breakthrough curves were collected. Travel time based tomographic inversion assumes that thermal transport is dominated by advection and the travel time of the thermal tracer can be related to the hydraulic conductivities of the aquifer. This assumption is valid in many shallow porous aquifers where the groundwater flow is fast. In our application, the travel time problem was treated by a tomographic solver, analogous to seismic tomography, to derive the hydraulic conductivity distribution. At the test site, a two-dimensional cross-well hydraulic conductivity profile was reconstructed with the travel time based inversion. The reconstructed profile corresponds well with the findings of the earlier hydraulic and geophysical experiments at the site.

Hydrologic monitoring of a waste-injection well near Milton, Florida, June 1975 - June 1977

USGS Publications Warehouse

Pascale, Charles A.; Martin, J.B.

1978-01-01

This report presents the hydraulic and chemical data collected from June 1, 1975, when injection began, to June 30, 1977 through a monitoring program at a deep-well waste-injection system at the American Cyanamid Company's plant near Milton, about 12 miles northwest of Pensacola. The injection system consists of a primary injection well, a standby injection well, and two deep monitor wells all completed open hole in the lower limestone of the Floridan aquifer and one shallow-monitor well completed in the upper limestone of the Floridan aquifer. Two of the monitor wells and the standby injection well are used to observe hydraulic and geochemical effects of waste injection in the injection zone at locations 8,180 feet northeast, 1,560 feet south, and 1,025 feet southwest of the primary injection well. The shallow-monitor well, used to observe any effects in the first permeable zone above the 200-foot-thick confining bed, is 28 feet north of the primary injection well. Since injection began in June 1975, 607 million gallons of treated industrial liquid waste with a pH of 4.6 to 6.3 and containing high concentrations of nitrate, organic nitrogen and carbon have been injected into a saline-water-filled limestone aquifer. Wellhead pressure at the injection well in June 1977 average 137 pounds per square inch and the hydraulic pressure gradient was 0.53 pound per square inch per foot of depth to the top of the injection zone. Water levels rose from 36 to 74 feet at the three wells used to monitor the injection zone during the 25-month period. The water level in the shallow-monitor well declined about 8 feet. No changes were detected in the chemical character of water from the shallow-monitor well and deep-monitor well-north. Increases in concentration of bicarbonate and dissolved organic carbon were detected in water from the deep-test monitor well in February 1976 and at the standby injection well in August 1976. In addition to increases in bicarbonate and dissolved organic carbon, sulfate, total organic nitrogen, and total nitrogen concentrations have also increased substantially in samples from these wells. Nitrogen gas concentrations in water samples collected at the three deep-monitor wells ranged from 19 to 176 milligrams per liter, methane from 4.5 to 11.4 milligrams per liter, and carbon dioxide from 7.7 to 44 milligrams per liter. The most probable number of denitrifying bacteria in water samples collected at the three deep-monitor wells ranged from less than 2 colonies to 17 colonies per 100 milliliters. None of the water samples collected in April 1977 at the three deep-monitor wells showed positive concentrations of acetone, ethanol, methanol, or acrylonitrile.

The relative merits of monitoring and domestic wells for ground water quality investigations

USGS Publications Warehouse

Jones, J.L.; Roberts, L.M.

1999-01-01

The results of two studies of the effect of agricultural land use on shallow ground water quality indicate that monitoring wells may be a better choice than domestic wells for studies of pesticide occurrence or transport, or for use as early-warning indicators of potential drinking water contamination. Because domestic wells represent the used resource, and because domestic well water may be affected by historical rather than current pesticide and land- use practices, domestic wells would be the best choice for an investigation of drinking water quality. The key difference between the domestic and monitoring wells appears to be that the monitoring wells in this study were installed exclusively to sample the shallowest possible ground water. For these studies, 48 shallow domestic wells and 41 monitoring wells were located randomly within two land-use settings (row crops and orchards) in an irrigated agricultural region of eastern Washington and sampled for 145 pesticides (including nine pesticide degradates) and common water quality indicators. Constructing and sampling monitoring wells required approximately four times the resources (including manpower and materials) as locating and sampling domestic wells. Sample collection and quality assurance procedures and analytical techniques were identical except that a portable submersible pump was required for monitoring wells. In both land-use settings, no significant difference in nitrate concentration was found between well types; however, the average number of pesticides detected per well was significantly higher (p<0.05) in the monitoring wells. A greater variety of pesticides was detected in monitoring wells; many were detected only in monitoring wells. More than 60% of detections of pesticides that were found only in domestic wells were of compounds that are no longer in use. These differences in ground water quality found in this study relate to the depth of the well and are apparently related to the age of ground water in the two types of wells and the greater effects of sorption, degradation, dilution, and dispersion that accompany longer groundwater residence times. The decision to invest resources in monitoring wells should be made in light of the study objective and should consider these differences in results from the two types of wells as well as the relative costs.

Mechanisms of electron acceptor utilization: Implications for simulating anaerobic biodegradation

USGS Publications Warehouse

Schreiber, M.E.; Carey, G.R.; Feinstein, D.T.; Bahr, J.M.

2004-01-01

Simulation of biodegradation reactions within a reactive transport framework requires information on mechanisms of terminal electron acceptor processes (TEAPs). In initial modeling efforts, TEAPs were approximated as occurring sequentially, with the highest energy-yielding electron acceptors (e.g. oxygen) consumed before those that yield less energy (e.g., sulfate). Within this framework in a steady state plume, sequential electron acceptor utilization would theoretically produce methane at an organic-rich source and Fe(II) further downgradient, resulting in a limited zone of Fe(II) and methane overlap. However, contaminant plumes often display much more extensive zones of overlapping Fe(II) and methane. The extensive overlap could be caused by several abiotic and biotic processes including vertical mixing of byproducts in long-screened monitoring wells, adsorption of Fe(II) onto aquifer solids, or microscale heterogeneity in Fe(III) concentrations. Alternatively, the overlap could be due to simultaneous utilization of terminal electron acceptors. Because biodegradation rates are controlled by TEAPs, evaluating the mechanisms of electron acceptor utilization is critical for improving prediction of contaminant mass losses due to biodegradation. Using BioRedox-MT3DMS, a three-dimensional, multi-species reactive transport code, we simulated the current configurations of a BTEX plume and TEAP zones at a petroleum- contaminated field site in Wisconsin. Simulation results suggest that BTEX mass loss due to biodegradation is greatest under oxygen-reducing conditions, with smaller but similar contributions to mass loss from biodegradation under Fe(III)-reducing, sulfate-reducing, and methanogenic conditions. Results of sensitivity calculations document that BTEX losses due to biodegradation are most sensitive to the age of the plume, while the shape of the BTEX plume is most sensitive to effective porosity and rate constants for biodegradation under Fe(III)-reducing and methanogenic conditions. Using this transport model, we had limited success in simulating overlap of redox products using reasonable ranges of parameters within a strictly sequential electron acceptor utilization framework. Simulation results indicate that overlap of redox products cannot be accurately simulated using the constructed model, suggesting either that Fe(III) reduction and methanogenesis are occurring simultaneously in the source area, or that heterogeneities in Fe(III) concentration and/or mineral type cause the observed overlap. Additional field, experimental, and modeling studies will be needed to address these questions. ?? 2004 Elsevier B.V. All rights reserved.

Assessment of intrinsic bioremediation of gasoline contamination in the shallow aquifer, Laurel Bay Exchange, Marine Corps Air Station Beaufort, South Carolina

USGS Publications Warehouse

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

1996-01-01

Laboratory, field, and digital solute-transport- modeling studies demonstrate that microorganisms indigenous to the shallow ground-water system at Laurel Bay Exchange, Marine Corps Air Station Beaufort, South Carolina, can degrade petroleum hydrocarbons in gasoline released at the site. Microorganisms in aquifer sediments incubated in the laboratory under aerobic and anaerobic conditions mineralized radiolabeled carbon 14-toluene to 14C-carbon dioxide with first-order rate constants of Kbio = -0.640 per day and Kbio = -0.003 per day, respectively. Digital solute- transport modeling using the numerical code SUTRA revealed that anaerobic biodegradation of benzene occurs with a first-order rate constant near Kbio = -0.00025 per day. Sandy aquifer material beneath Laurel Bay Exchange is characterized by relatively high hydraulic conductivities (Kaq = 8.9 to 17.3 feet per day), average ground-water flow rate of about 60 feet per year, and a relatively uniform hydraulic gradient of 0.004 feet per foot. The sandy aquifer material also has low adsorptive potentials for toluene and benzene (both about Kad = 2.0 x 10-9 cubic feet per milligram), because of the lack of natural organic matter in the aquifer. The combination of this ground-water-flow rate and absence of significant adsorptive capacity in the aquifer permits toluene and benzene concentrations to be detected downgradient from the source area in monitoring wells, even though biodegradation of these compounds has been demonstrated. Solute-transport simulations, however, indicate that toluene and benzene will not reach the Broad River, the nearest point of contact with wildlife or human populations, about 3,600 feet west of the site boundary. These simulations also show that contamination will not be transported to the nearest Marine Corps property line about 2,400 feet south of the site. This is primarily because the source of contaminants has essentially been removed, and the low adsorptive capacity of the aquifer sediments has prevented the occurrence of an adsorbed, continuous source of petroleum hydrocarbons. Therefore, digital simulations of toluene and benzene transport at Laurel Bay Exchange indicate that intrinsic bioremediation could be a successful remediation alternative for prohibiting transport of dissolved toluene and benzene to the Broad River.

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.

Monitoring well utility in a heterogeneous DNAPL source zone area: Insights from proximal multilevel sampler wells and sampling capture-zone modelling.

PubMed

McMillan, Lindsay A; Rivett, Michael O; Wealthall, Gary P; Zeeb, Peter; Dumble, Peter

2018-03-01

Groundwater-quality assessment at contaminated sites often involves the use of short-screen (1.5 to 3 m) monitoring wells. However, even over these intervals considerable variation may occur in contaminant concentrations in groundwater adjacent to the well screen. This is especially true in heterogeneous dense non-aqueous phase liquid (DNAPL) source zones, where cm-scale contamination variability may call into question the effectiveness of monitoring wells to deliver representative data. The utility of monitoring wells in such settings is evaluated by reference to high-resolution multilevel sampler (MLS) wells located proximally to short-screen wells, together with sampling capture-zone modelling to explore controls upon well sample provenance and sensitivity to monitoring protocols. Field data are analysed from the highly instrumented SABRE research site that contained an old trichloroethene source zone within a shallow alluvial aquifer at a UK industrial facility. With increased purging, monitoring-well samples tend to a flow-weighted average concentration but may exhibit sensitivity to the implemented protocol and degree of purging. Formation heterogeneity adjacent to the well-screen particularly, alongside pump-intake position and water level, influence this sensitivity. Purging of low volumes is vulnerable to poor reproducibility arising from concentration variability predicted over the initial 1 to 2 screen volumes purged. Marked heterogeneity may also result in limited long-term sample concentration stabilization. Development of bespoke monitoring protocols, that consider screen volumes purged, alongside water-quality indicator parameter stabilization, is recommended to validate and reduce uncertainty when interpreting monitoring-well data within source zone areas. Generalised recommendations on monitoring well based protocols are also developed. A key monitoring well utility is their proportionately greater sample draw from permeable horizons constituting a significant contaminant flux pathway and hence representative fraction of source mass flux. Acquisition of complementary, high-resolution, site monitoring data, however, vitally underpins optimal interpretation of monitoring-well datasets and appropriate advancement of a site conceptual model and remedial implementation. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

The effects of artificial recharge on groundwater levels and water quality in the west hydrogeologic unit of the Warren subbasin, San Bernardino County, California

USGS Publications Warehouse

Stamos, Christina L.; Martin, Peter; Everett, Rhett; Izbicki, John A.

2013-01-01

Between the late 1940s and 1994, groundwater levels in the Warren subbasin, California, declined by as much as 300 feet because pumping exceeded sparse natural recharge. In response, the local water district, Hi-Desert Water District, implemented an artificial-recharge program in early 1995 using imported water from the California State Water Project. Subsequently, the water table rose by as much as 250 feet; however, a study done by the U.S. Geological Survey found that the rising water table entrained high-nitrate septic effluent, which caused nitrate (as nitrogen) concentrations in some wells to increase to more than the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter.. A new artificial-recharge site (site 3) was constructed in 2006 and this study, which started in 2004, was done to address concerns about the possible migration of nitrates in the unsaturated zone. The objectives of this study were to: (1) characterize the hydraulic, chemical, and microbiological properties of the unsaturated zone; (2) monitor changes in water levels and water quality in response to the artificial-recharge program at site 3; (3) determine if nitrates from septic effluent infiltrated through the unsaturated zone to the water table; (4) determine the potential for nitrates within the unsaturated zone to mobilize and contaminate the groundwater as the water table rises in response to artificial recharge; and (5) determine the presence and amount of dissolved organic carbon because of its potential to react with disinfection byproducts during the treatment of water for public use. Two monitoring sites were installed and instrumented with heat-dissipation probes, advanced tensiometers, suction-cup lysimeters, and wells so that the arrival and effects of recharging water from the State Water Project through the 250 to 425 foot-thick unsaturated zone and groundwater system could be closely observed. Monitoring site YVUZ-1 was located between two recharge ponds in the middle of site 3, and YVUZ-2 was located approximately 1,200 feet down-gradient and to the southeast in an area where septic systems have been in use since about 1960. Site YVUZ-3 only went to a depth of 42 feet and was used to sample the upper part of the unsaturated zone near a golf course. Prior to the start of artificial recharge at site 3, nitrate concentrations reported as nitrogen from the soil leachate below YVUZ-1 did not exceed 1.58 milligrams per kilogram. Nitrate-reducing bacteria concentrations of 4,300 most probable number were found at about 220 feet below land surface and at the top of the water table at YVUZ-1. Nitrate concentrations at YVUZ-2 reached a maximum concentration of about 25 milligrams per kilogram between about 100 and 121 feet below land surface; concentrations of nitrate-reducing or denitrifying bacteria were as high as 21,000 most probable number at 36 feet below land surface but did not exceed 40 most probable number below about 150 feet below land surface. Between June 2006 and September 2009, more than 9,800 acre feet of water from the State Water Project was released to site 3 ponds. The infiltration of the recharge water was predominantly vertical with limited lateral spreading to a depth of about 200 feet below land surface at YVUZ-1. Lateral spreading of the recharge water with depth was caused by geologic heterogeneities within the unsaturated zone, and resulted in varied arrival times of the recharge water to the instruments and slower rates of vertical movement with depth. No abrupt changes in soil moisture were observed at YVUZ-2, indicating that the recharge water had not reached that site by September 2009. Water levels from the monitoring wells at both sites and from five production wells nearby showed that the water table rose at a mean rate of about 0.08 feet per day between June 2006 and January 2009. The arrival of the water from the State Water Project caused relatively rapid changes in the stable-isotopic ratios from the lysimeters at YVUZ-1. The estimated average rate of infiltration of the recharge water through the unsaturated zone ranged from 3.7 to 25 feet per day. The recharge water arrived at the monitoring well below the recharge ponds between August 2007 and March 2008; the rate of vertical movement to the monitoring well was between 0.6 and 0.9 feet per day. By September 2008, a production well located 375 feet west of site 3 was producing almost 100 percent infiltrated recharge water. By contrast, the stable-isotope data from the lysimeters at YVUZ-2 showed that the recharge water had not reached this site by September 2009, but that septic effluent in the unsaturated zone likely had mixed with the native pore water to at least 154 feet below land surface. Assuming vertical infiltration, the minimum rate of infiltration of septic effluent since 1960 was about 3 feet per year. The isotopic data from the lysimeters at YVUZ-3 indicated two different sources of water to the upper 43 feet–irrigation-return flow and precipitation. Nitrate concentrations of the water from the State Water Project did not exceed 1 milligram per liter. Prior to artificial recharge, nitrate concentrations of the pore water at YVUZ-1 ranged between 6 to 18.2 milligrams per liter. After the arrival of the recharge water, the nitrate concentrations from the lysimeters and well at YVUZ-1 decreased to less than 1 milligram per liter, with the exception of samples collected at 205.5 feet, which did not exceed 4.12 milligrams per liter. The decrease in nitrate concentrations after artificial recharge indicated that the rising water table did not result in an increase of nitrates below YVUZ-1. At YVUZ-2, nitrate concentrations ranged between 12 to 479 milligrams per liter. The highest nitrate concentrations were at 92 feet below land surface and were almost seven times that of samples collected from a nearby septic tank. Nitrate concentrations from the lysimeter at 273 feet below land surface increased from 6 to almost 58 milligrams per liter after it was saturated by the rising water table in December 2007. These increases could be the result of the mobilization of high-nitrate water from regional sources of septic effluent after saturation, or the result of high-nitrate water present at the top of the water table that may be diluted deeper in the aquifer. Nitrate concentrations in groundwater from five nearby production wells and from both monitoring wells were less than 5 milligrams per liter before artificial recharge started. Nitrate concentrations decreased to less than 3 milligrams per liter in three of the production wells and the monitoring well below the recharge ponds after artificial recharge. Dissolved organic carbon concentrations were measured in the recharge water and groundwater because of the potential for dissolved organic carbon to react with chlorine to form trihalomethanes during the water-treatment process. The dissolved organic carbon concentrations of the recharge water were 3.1 milligrams per liter or less, and dissolved organic carbon concentrations of the groundwater were less than 1 milligram per liter. Even though recharge water was present in some of the wells by September 2008, the concentrations of both dissolved organic carbon and trihalomethane formation potential in the groundwater did not increase. Interpretation of these data suggests that the dissolved organic carbon from the recharge water is altered or metabolized in the unsaturated zone, either by absorption to the grain particles in the soil or by microbiological processes.

Groundwater monitoring of hydraulic fracturing in California: Recommendations for permit-required monitoring

NASA Astrophysics Data System (ADS)

Esser, B. K.; Beller, H. R.; Carroll, S.; Cherry, J. A.; Jackson, R. B.; Jordan, P. D.; Madrid, V.; Morris, J.; Parker, B. L.; Stringfellow, W. T.; Varadharajan, C.; Vengosh, A.

2015-12-01

California recently passed legislation mandating dedicated groundwater quality monitoring for new well stimulation operations. The authors provided the State with expert advice on the design of such monitoring networks. Factors that must be considered in designing a new and unique groundwater monitoring program include: Program design: The design of a monitoring program is contingent on its purpose, which can range from detection of individual well leakage to demonstration of regional impact. The regulatory goals for permit-required monitoring conducted by operators on a well-by-well basis will differ from the scientific goals of a regional monitoring program conducted by the State. Vulnerability assessment: Identifying factors that increase the probability of transport of fluids from the hydrocarbon target zone to a protected groundwater zone enables the intensity of permit-required monitoring to be tiered by risk and also enables prioritization of regional monitoring of groundwater basins based on vulnerability. Risk factors include well integrity; proximity to existing wellbores and geologic features; wastewater disposal; vertical separation between the hydrocarbon and groundwater zones; and site-specific hydrogeology. Analyte choice: The choice of chemical analytes in a regulatory monitoring program is guided by the goals of detecting impact, assuring public safety, preventing resource degradation, and minimizing cost. Balancing these goals may be best served by tiered approach in which targeted analysis of specific chemical additives is triggered by significant changes in relevant but more easily analyzed constituents. Such an approach requires characterization of baseline conditions, especially in areas with long histories of oil and gas development. Monitoring technology: Monitoring a deep subsurface process or a long wellbore is more challenging than monitoring a surface industrial source. The requirement for monitoring multiple groundwater aquifers across a range of depths and of monitoring at deeper depths than is typical for regulatory monitoring programs requires consideration of monitoring technology, which can range from clusters of wells to multiple wells in a single wellbore to multi-level systems in a single cased wellbore.

Hydrologic data for a subsurface waste-injection site at Mulberry, Florida; 1972-77

USGS Publications Warehouse

Wilson, William Edward; Parsons, David C.; Spechler, R.M.

1979-01-01

Since October 1972, industrial liquid waste has been injected into a brine aquifer of limestone and dolomite in Mulberry, FL., at a depth of more than 4,000 feet below land surface. During 1977, the injection rate was about 8.8 million gallons per month. To determine what effect the injected waste has on the ground-water body, water levels have been measured and water samples collected from two monitor wells that tap different permeable zones above the injection zone, and from a satellite monitor well that taps the injection zone. The monitor wells are in the annulus of the injection well, and the satellite monitor well is 2,291 feet from the injection well. This report updates previous data reports and includes all hydrologic data collected by the U.S. Geological Survey during 1972-77. Included is a table of well-construction data, a graph showing the volume of waste injected each month, and hydrographs of the annulus monitor wells and the satellite monitor well. (Woodard-USGS)

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.

Role of physical heterogeneity in the interpretation of small-scale laboratory and field observations of bacteria, microbial-sized microsphere, and bromide transport through aquifer sediments

USGS Publications Warehouse

Harvey, Ronald W.; Kinner, Nancy E.; MacDonald, Dan; Metge, David W.; Bunn, Amoret

1993-01-01

The effect of physical variability upon the relative transport behavior of microbial-sized microspheres, indigenous bacteria, and bromide was examined in field and flow-through column studies for a layered, but relatively well sorted, sandy glaciofluvial aquifer. These investigations involved repacked, sieved, and undisturbed aquifer sediments. In the field, peak abundance of labeled bacteria traveling laterally with groundwater flow 6 m downgradient from point of injection was coincident with the retarded peak of carboxylated microspheres (retardation factor, RF = 1.7) at the 8.8 m depth, but preceded the bromide peak and the retarded microsphere peak (RF = 1.5) at the 9.0 m depth. At the 9.5 m depth, the bacterial peak was coincident with both the bromide and the microsphere peaks. Although sorption appeared to be a predominant mechanism responsible for immobilization of microbial-sized microspheres in the aquifer, straining appeared to be primarily responsible for their removal in 0.6-m-long columns of repacked, unsieved aquifer sediments. The manner in which the columns were packed also affected optimal size for microsphere transport, which in one experiment was near the size of the small (∼2 μm) groundwater protozoa (flagellates). These data suggest that variability in aquifer sediment structure can be important in interpretation of both small-scale field and laboratory experiments examining microbial transport behavior.

Microbially mediated clinoptilolite regeneration in a multifunctional permeable reactive barrier used to remove ammonium from landfill leachate contamination: laboratory column evaluation.

PubMed

Nooten, Thomas Van; Diels, Ludo; Bastiaens, Leen

2010-05-01

This study focuses on multifunctional permeable reactive barrier (multibarrier) technology, combining microbial degradation and abiotic ion exchange processes for removal of ammonium from landfill leachate contamination. The sequential multibarrier concept relies on the use of a clinoptilolite-filled buffer compartment to ensure a robust ammonium removal in case of temporary insufficient microbial activities. An innovative strategy was developed to allow in situ clinoptilolite regeneration. Laboratory-scale clinoptilolite-filled columns were first saturated with ammonium, using real landfill leachate as well as synthetic leachates as feed media. Other inorganic metal cations, typically present in landfill leachate, had a detrimental influence on the ammonium removal capacity by competing for clinoptilolite exchange sites. On the other hand, the metals had a highly favorable impact on regeneration of the saturated material. Feeding the columns with leachate deprived from ammonium (e.g., by microbial nitrification in an upgradient compartment), resulted in a complete release of the previously sorbed ammonium from the clinoptilolite, due to exchange with metal cations present in the leachate. The released ammonium is then available for microbial consumption in a downgradient compartment. The regeneration process resulted in a slightly increased ammonium exchange capacity afterward. The described strategy throws a new light on sustainable use of sorption materials for in situ groundwater remediation, by avoiding the need for material replacement and the use of external chemical regenerants.

Analysis of trace neptunium in the vicinity of underground nuclear tests at the Nevada National Security Site

DOE PAGES

Zhao, P.; Tinnacher, R. M.; Zavarin, M.; ...

2014-11-01

A high sensitivity analytical method for 237Np analysis was developed and applied to groundwater samples from the Nevada National Security Site (NNSS) using short-lived 239Np as a yield tracer and HR magnetic sector ICP-MS. The 237Np concentrations in the vicinity of the Almendro, Cambric, Dalhart, Cheshire, and Chancellor underground nuclear test locations range from <4 × 10 -4 to 2.6 mBq/L (6 × 10 -17–4.2 × 10 -13 mol/L). All measured 237Np concentrations are well below the drinking water maximum contaminant level for alpha emitters identified by the U.S. EPA (560 mBq/L). Nevertheless, 237Np remains an important indicator for radionuclidemore » transport rates at the NNSS. Retardation factor ratios were used to compare the mobility of 237Np to that of other radionuclides. The results suggest that 237Np is less mobile than tritium and other non-sorbing radionuclides ( 14C, 36Cl, 99Tc and 129I) as expected. Surprisingly, 237Np and plutonium ( 239,240Pu) retardation factors are very similar. It is possible that Np(IV) exists under mildly reducing groundwater conditions and exhibits a retardation behavior that is comparable to Pu(IV). Independent of the underlying process, 237Np is migrating downgradient from NNSS underground nuclear tests at very low but measureable concentrations.« less

Transport of chromium and selenium in the suboxic zone of a shallow aquifer: Influence of redox and adsorption reactions

USGS Publications Warehouse

Kent, D.B.; Davis, J.A.; Anderson, L.C.D.; Rea, B.A.; Waite, T.D.

1994-01-01

Breakthrough of Cr(VI) (chromate), Se(VI) (selenate), and O2 (dissolved oxygen) was observed in tracer tests conducted in a shallow, sand and gravel aquifer with mildly reducing conditions. Loss of Cr, probably due to reduction of Cr(VI) to Cr(III) and irreversible sorption of Cr(III), occurred along with slight retardation of Cr(VI), owing to reversible sorption. Reduction of Se(VI) and O2 was thermodynamically feasible but did not occur, indicating conditions, were unfavorable to microbial reduction. Cr(VI) reduction by constituents of aquifer sediments did not achieve local equilibrium during transport. The reduction rate was probably limited by incomplete contact between Cr(VI) transported along predominant flow paths and reductants located in regions within aquifer sediments of comparatively low permeability. Scatter in the amount of Cr reduction calculated from individual breakthrough curves at identical distances downgradient probably resulted from heterogeneities in the distribution of reductants in the sediments. Predictive modeling of the transport and fate of redox-sensitive solutes cannot be based strictly on thermodynamic considerations; knowledge of reaction rates is critical. Potentially important mass transfer rate limitations between solutes and reactants in sediments as well as heterogeneities in the distribution of redox properties in aquifers complicate determination of limiting rates for use in predictive simulations of the transport of redox-sensitive contaminants in groundwater.

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.

Calendar years 1989 and 1990 monitoring well installation program Y-12 plant, Oak Ridge, Tennessee

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

Not Available

1991-10-01

This report documents the well-construction activities at the Y-12 Plant in Oak Ridge, Tennessee during 1989 and 1990. The well- construction program consisted of installing seventy-five monitoring wells. Geologists from ERCE (formally the Engineering, Design and Geosciences Group) and Martin Marietta Energy Systems (Energy Systems), supervised and documented well-construction activities and monitored for health and safety concerns. Sixty-seven monitoring wells were installed under the supervision of an ERCE geologist from March 1989 to September 1990. Beginning in September 1990, Energy Systems supervised drilling activities for eight monitoring wells, the last of which was completed in December 1990. 9 refs., 3more » figs., 2 tabs.« less

Y-12 Groundwater Protection Program Monitoring Optimization Plan for Groundwater Monitoring Wells at the U.S. Department of Energy Y-12 National Security Complex, Oak Ridge, Tennessee

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

None, None

This document is the monitoring optimization plan for groundwater monitoring wells associated with the U.S. Department of Energy (DOE) Y-12 National Security Complex (Y-12) in Oak Ridge, Tennessee. The plan describes the technical approach that is implemented under the Y-12 Groundwater Protection Program (GWPP) to focus available resources on the monitoring wells at Y-12 that provide the most useful hydrologic and groundwater quality monitoring data. The technical approach is based on the GWPP status designation for each well. Under this approach, wells granted “active” status are used by the GWPP for hydrologic monitoring and/or groundwater quality sampling, whereas wells grantedmore » “inactive” status are not used for either purpose. The status designation also defines the frequency at which the GWPP will inspect applicable wells, the scope of these well inspections, and extent of any maintenance actions initiated by the GWPP. Details regarding the ancillary activities associated with implementation of this plan (e.g., well inspection) are deferred to the referenced GWPP plans.« less

Lithology, hydraulic properties, and water quality of the Sandstone Aquifer in the northwestern part of the Bad River Indian Reservation, Wisconsin, 1998-1999

USGS Publications Warehouse

Dunning, Charles P.

2005-01-01

The Precambrian sandstone aquifer in the northwestern part of the Bad River Band of Lake Superior Tribe of Chippewa Indians Reservation, Ashland County, Wisconsin, provides much of the drinking water to area residents. A study was undertaken in cooperation with the Bad River Tribe to provide specific information about the lithology, hydraulic properties, and water quality of the sandstone aquifer. During 1998 and 1999, the U.S. Geological Survey installed three monitoring wells, collected and analyzed lithologic and water samples, and conducted geophysical logging and aquifer tests to characterize the sandstone aquifer. The two monitoring wells in the southeastern part of the study area, the Diaperville Monitoring Well #1 (Diaperville MW #1) and the Tolman Monitoring Well #1 (Tolman MW #1) , are believed to have encountered older Middle Proterozoic Oronto Group sandstones. The sandstone encountered in the Ackley Monitoring Well #1 (Ackley MW #1) is believed to be Chequamegon Sandstone of the Late Proterozoic Bayfield Group. This interpretation is based on previous studies, as well as thin- section analysis of sandstone core recovered from the Ackley Monitoring Well #1. Results of aquifer tests conducted in the Diaperville Monitoring Well #1 and the Tolman Monitoring Well #1 provide ranges for hydraulic param - eter values in the sandstone aquifer: transmissivity ranges from 83 to 509 square feet per day; hydraulic conductivity ranges from 1.6 to 4.5 feet per day; storativity ranges from 0.00019 to 0.00046; and specific capacity ranges from 0.22 to 0.67 gallons per minute per foot. Though high- and low-angle fractures are present in Ackley Monitoring Well #1 core, the hydraulic properties of the bedrock appear to be due largely to the matrix porosity measured in thin section (16–21 percent) and permeability of the sandstone. The aquifer test for the Diaperville Monitoring Well #1 resulted in observed drawdown in nearby glacial wells, evidence of a hydraulic connection between the sandstone aquifer and the glacial deposits. Major ion analyses indicate that the water sampled from the sandstone aquifer at the Ackley site is of the calcium-magnesium-sodium- bicarbonate type. Based on a single sampling set, volatile organic constituents were not detected in water samples from the Diaperville Monitoring Well #1 or the Ackley Monitoring Well #1. 

Parametric fate and transport profiling for selective groundwater monitoring at closed landfills: a case study.

PubMed

Sizirici, Banu; Tansel, Berrin

2015-04-01

Monitoring contaminant concentrations in groundwater near closed municipal solid waste landfills requires long term monitoring program which can require significant investment for monitoring efforts. The groundwater monitoring data from a closed landfill in Florida was analyzed to reduce the monitoring efforts. The available groundwater monitoring data (collected over 20 years) were analyzed (i.e., type, concentration and detection level) to identify the trends in concentrations of contaminants and spatial mobility characteristics of groundwater (i.e., groundwater direction, retardation characteristics of contaminants, groundwater well depth, subsoil characteristics), to identify critical monitoring locations. Among the 7 groundwater monitoring well clusters (totaling 22 wells) in landfill, the data from two monitoring well clusters (totaling 7 wells) located along direction of groundwater flow showed similarities (the highest concentrations and same contaminants). These wells were used to assess the transport characteristics of the contaminants. Some parameters (e.g., iron, sodium, ammonia as N, chlorobenzene, 1,4-dichlorobenzene) showed decreasing trends in the groundwater due to soil absorption and retardation. Metals were retarded by ion exchange and their concentration increased by depth indicating soil reached breakthrough over time. Soil depth did not have a significant effect on the concentrations of volatile organic contaminants. Based on the analyses, selective groundwater monitoring modifications were developed for effective monitoring to acquire data from the most critical locations which may be impacted by leachate mobility. The adjustments in the sampling strategy reduced the amount of data collected by as much as 97.7% (i.e., total number of parameters monitored). Effective groundwater sampling strategies can save time, effort and monitoring costs while improving the quality of sample handling and data analyses for better utilization of post closure monitoring funds. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

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.

Application of Mortar Coupling in Multiscale Modelling of Coupled Flow, Transport, and Biofilm Growth in Porous Media

NASA Astrophysics Data System (ADS)

Laleian, A.; Valocchi, A. J.; Werth, C. J.

2017-12-01

Multiscale models of reactive transport in porous media are capable of capturing complex pore-scale processes while leveraging the efficiency of continuum-scale models. In particular, porosity changes caused by biofilm development yield complex feedbacks between transport and reaction that are difficult to quantify at the continuum scale. Pore-scale models, needed to accurately resolve these dynamics, are often impractical for applications due to their computational cost. To address this challenge, we are developing a multiscale model of biofilm growth in which non-overlapping regions at pore and continuum spatial scales are coupled with a mortar method providing continuity at interfaces. We explore two decompositions of coupled pore-scale and continuum-scale regions to study biofilm growth in a transverse mixing zone. In the first decomposition, all reaction is confined to a pore-scale region extending the transverse mixing zone length. Only solute transport occurs in the surrounding continuum-scale regions. Relative to a fully pore-scale result, we find the multiscale model with this decomposition has a reduced run time and consistent result in terms of biofilm growth and solute utilization. In the second decomposition, reaction occurs in both an up-gradient pore-scale region and a down-gradient continuum-scale region. To quantify clogging, the continuum-scale model implements empirical relations between porosity and continuum-scale parameters, such as permeability and the transverse dispersion coefficient. Solutes are sufficiently mixed at the end of the pore-scale region, such that the initial reaction rate is accurately computed using averaged concentrations in the continuum-scale region. Relative to a fully pore-scale result, we find accuracy of biomass growth in the multiscale model with this decomposition improves as the interface between pore-scale and continuum-scale regions moves downgradient where transverse mixing is more fully developed. Also, this decomposition poses additional challenges with respect to mortar coupling. We explore these challenges and potential solutions. While recent work has demonstrated growing interest in multiscale models, further development is needed for their application to field-scale subsurface contaminant transport and remediation.

Implications of matrix diffusion on 1,4-dioxane persistence at contaminated groundwater sites.

PubMed

Adamson, David T; de Blanc, Phillip C; Farhat, Shahla K; Newell, Charles J

2016-08-15

Management of groundwater sites impacted by 1,4-dioxane can be challenging due to its migration potential and perceived recalcitrance. This study examined the extent to which 1,4-dioxane's persistence was subject to diffusion of mass into and out of lower-permeability zones relative to co-released chlorinated solvents. Two different release scenarios were evaluated within a two-layer aquifer system using an analytical modeling approach. The first scenario simulated a 1,4-dioxane and 1,1,1-TCA source zone where spent solvent was released. The period when 1,4-dioxane was actively loading the low-permeability layer within the source zone was estimated to be <3years due to its high effective solubility. While this was approximately an order-of-magnitude shorter than the loading period for 1,1,1-TCA, the mass of 1,4-dioxane stored within the low-permeability zone at the end of the simulation period (26kg) was larger than that predicted for 1,1,1-TCA (17kg). Even 80years after release, the aqueous 1,4-dioxane concentration was still several orders-of-magnitude higher than potentially-applicable criteria. Within the downgradient plume, diffusion contributed to higher concentrations and enhanced penetration of 1,4-dioxane into the low-permeability zones relative to 1,1,1-TCA. In the second scenario, elevated 1,4-dioxane concentrations were predicted at a site impacted by migration of a weak source from an upgradient site. Plume cutoff was beneficial because it could be implemented in time to prevent further loading of the low-permeability zone at the downgradient site. Overall, this study documented that 1,4-dioxane within transmissive portions of the source zone is quickly depleted due to characteristics that favor both diffusion-based storage and groundwater transport, leaving little mass to treat using conventional means. Furthermore, the results highlight the differences between 1,4-dioxane and chlorinated solvent source zones, suggesting that back diffusion of 1,4-dioxane mass may be serving as the dominant long-term "secondary source" at many contaminated sites that must be managed using alternative approaches. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of groundwater withdrawal on borehole flow and salinity measured in deep monitor wells in Hawai'i-implications for groundwater management

USGS Publications Warehouse

Rotzoll, Kolja

2010-01-01

Water-resource managers in Hawai`i rely heavily on salinity profiles from deep monitor wells to estimate the thickness of freshwater and the depth to the midpoint of the transition zone between freshwater and saltwater in freshwater-lens systems. The deep monitor wells are typically open boreholes below the water table and extend hundreds of feet below sea level. Because of possible borehole-flow effects, there is concern that salinity profiles measured in these wells may not accurately reflect the salinity distribution in the aquifer and consequently lead to misinterpretations that adversely affect water-resource management. Steplike changes in salinity or temperature with depth in measured profiles from nonpumped deep monitor wells may be indicative of water moving within the well, and such changes are evident to some extent in all available profiles. The maximum vertical step length, or displacement, in measured profiles ranges from 7 to 644 feet. Vertical steps longer than 70 feet exceed the typical thickness of massive lava flows; they therefore cannot be attributed entirely to geologic structure and may be indicative of borehole flow. The longest vertical steps occur in monitor wells located in southern O'ahu, coinciding with the most heavily developed part of the aquifer. Although regional groundwater withdrawals have caused a thinning of the freshwater lens over the past several decades, the measured midpoint of the transition zone in most deep monitor wells has shown only inconsequential depth displacement in direct response to short-term variations in withdrawals from nearby production wells. For profiles from some deep monitor wells, however, the depth of the measured top of the transition zone, indicated by a specific-conductance value of 1,000 microsiemens per centimeter, has risen several hundred feet in response to withdrawals from nearby production wells. For these deep monitor wells, monitoring the apparent top of the transition zone may not provide an accurate indication of water quality in the adjacent aquifer. Hence, the measured midpoint in boreholes is a better proxy for freshwater-lens thickness. Brackish water transported upward in a deep monitor well can exit the borehole in the upper, freshwater part of the aquifer and affect the water quality in nearby production wells. Piezometers installed at different depths will provide the best information on aquifer salinity because they are unaffected by borehole flow. Despite the effects of borehole flow, monitoring the midpoint in deep monitor wells is still useful to identify long-term trends in the movement of the transition zone.

Significant Association between Sulfate-Reducing Bacteria and Uranium-Reducing Microbial Communities as Revealed by a Combined Massively Parallel Sequencing-Indicator Species Approach▿ †

PubMed Central

Cardenas, Erick; Wu, Wei-Min; Leigh, Mary Beth; Carley, Jack; Carroll, Sue; Gentry, Terry; Luo, Jian; Watson, David; Gu, Baohua; Ginder-Vogel, Matthew; Kitanidis, Peter K.; Jardine, Philip M.; Zhou, Jizhong; Criddle, Craig S.; Marsh, Terence L.; Tiedje, James M.

2010-01-01

Massively parallel sequencing has provided a more affordable and high-throughput method to study microbial communities, although it has mostly been used in an exploratory fashion. We combined pyrosequencing with a strict indicator species statistical analysis to test if bacteria specifically responded to ethanol injection that successfully promoted dissimilatory uranium(VI) reduction in the subsurface of a uranium contamination plume at the Oak Ridge Field Research Center in Tennessee. Remediation was achieved with a hydraulic flow control consisting of an inner loop, where ethanol was injected, and an outer loop for flow-field protection. This strategy reduced uranium concentrations in groundwater to levels below 0.126 μM and created geochemical gradients in electron donors from the inner-loop injection well toward the outer loop and downgradient flow path. Our analysis with 15 sediment samples from the entire test area found significant indicator species that showed a high degree of adaptation to the three different hydrochemical-created conditions. Castellaniella and Rhodanobacter characterized areas with low pH, heavy metals, and low bioactivity, while sulfate-, Fe(III)-, and U(VI)-reducing bacteria (Desulfovibrio, Anaeromyxobacter, and Desulfosporosinus) were indicators of areas where U(VI) reduction occurred. The abundance of these bacteria, as well as the Fe(III) and U(VI) reducer Geobacter, correlated with the hydraulic connectivity to the substrate injection site, suggesting that the selected populations were a direct response to electron donor addition by the groundwater flow path. A false-discovery-rate approach was implemented to discard false-positive results by chance, given the large amount of data compared. PMID:20729318

Significant association between sulfate-reducing bacteria and uranium-reducing microbial communities as revealed by a combined massively parallel sequencing-indicator species approach.

PubMed

Cardenas, Erick; Wu, Wei-Min; Leigh, Mary Beth; Carley, Jack; Carroll, Sue; Gentry, Terry; Luo, Jian; Watson, David; Gu, Baohua; Ginder-Vogel, Matthew; Kitanidis, Peter K; Jardine, Philip M; Zhou, Jizhong; Criddle, Craig S; Marsh, Terence L; Tiedje, James M

2010-10-01

Massively parallel sequencing has provided a more affordable and high-throughput method to study microbial communities, although it has mostly been used in an exploratory fashion. We combined pyrosequencing with a strict indicator species statistical analysis to test if bacteria specifically responded to ethanol injection that successfully promoted dissimilatory uranium(VI) reduction in the subsurface of a uranium contamination plume at the Oak Ridge Field Research Center in Tennessee. Remediation was achieved with a hydraulic flow control consisting of an inner loop, where ethanol was injected, and an outer loop for flow-field protection. This strategy reduced uranium concentrations in groundwater to levels below 0.126 μM and created geochemical gradients in electron donors from the inner-loop injection well toward the outer loop and downgradient flow path. Our analysis with 15 sediment samples from the entire test area found significant indicator species that showed a high degree of adaptation to the three different hydrochemical-created conditions. Castellaniella and Rhodanobacter characterized areas with low pH, heavy metals, and low bioactivity, while sulfate-, Fe(III)-, and U(VI)-reducing bacteria (Desulfovibrio, Anaeromyxobacter, and Desulfosporosinus) were indicators of areas where U(VI) reduction occurred. The abundance of these bacteria, as well as the Fe(III) and U(VI) reducer Geobacter, correlated with the hydraulic connectivity to the substrate injection site, suggesting that the selected populations were a direct response to electron donor addition by the groundwater flow path. A false-discovery-rate approach was implemented to discard false-positive results by chance, given the large amount of data compared.

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.

Methyl tert-butyl ether biodegradation by indigenous aquifer microorganisms under natural and artificial oxic conditions

USGS Publications Warehouse

Landmeyer, J.E.; Chapelle, F.H.; Herlong, H.H.; Bradley, P.M.

2001-01-01

Microbial communities indigenous to a shallow groundwater system near Beaufort, SC, degraded milligram per liter concentrations of methyl tert-butyl ether (MTBE) under natural and artificial oxic conditions. Significant MTBE biodegradation was observed where anoxic, MTBE-contaminated groundwater discharged to a concrete-lined ditch. In the anoxic groundwater adjacent to the ditch, concentrations of MTBE were > 1 mg/L. Where groundwater discharge occurs, dissolved oxygen (DO) concentrations beneath the ditch exceeded 1.0 mg/L to a depth of 1.5 m, and MTBE concentrations decreased to <1 ??g/L prior to discharge. MTBE mass flux calculations indicate that 96% of MTBE mass loss occurs in the relatively small oxic zone prior to discharge. Samples of a natural microbial biofilm present in the oxic zone beneath the ditch completely degraded [U-14C]MTBE to [14C]CO2 in laboratory liquid culture studies, with no accumulation of intermediate compounds. Upgradient of the ditch in the anoxic, MTBE and BTEX-contaminated aquifer, addition of a soluble oxygen release compound resulted in oxic conditions and rapid MTBE biodegradation by indigenous microorganisms. In an observation well located closest to the oxygen addition area, DO concentrations increased from 0.4 to 12 mg/L in <60 days and MTBE concentrations decreased from 20 to 3 mg/L. In the same time period at a downgradient observation well, DO increased from <0.2 to 2 mg/L and MTBE concentrations decreased from 30 to <5 mg/L. These results indicate that microorganisms indigenous to the groundwater system at this site can degrade milligram per liter concentrations of MTBE under natural and artificial oxic conditions.

Chemical evolution of groundwater in the Wilcox aquifer of the northern Gulf Coastal Plain, USA

NASA Astrophysics Data System (ADS)

Haile, Estifanos; Fryar, Alan E.

2017-12-01

The Wilcox aquifer is a major groundwater resource in the northern Gulf Coastal Plain (lower Mississippi Valley) of the USA, yet the processes controlling water chemistry in this clastic aquifer have received relatively little attention. The current study combines analyses of solutes and stable isotopes in groundwater, petrography of core samples, and geochemical modeling to identify plausible reactions along a regional flow path ˜300 km long. The hydrochemical facies evolves from Ca-HCO3 upgradient to Na-HCO3 downgradient, with a sequential zonation of terminal electron-accepting processes from Fe(III) reduction through SO4 2- reduction to methanogenesis. In particular, decreasing SO4 2- and increasing δ34S of SO4 2- along the flow path, as well as observations of authigenic pyrite in core samples, provide evidence of SO4 2- reduction. Values of δ13C in groundwater suggest that dissolved inorganic carbon is contributed both by oxidation of sedimentary organic matter and calcite dissolution. Inverse modeling identified multiple plausible sets of reactions between sampled wells, which typically involved cation exchange, pyrite precipitation, CH2O oxidation, and dissolution of amorphous Fe(OH)3, calcite, or siderite. These reactions are consistent with processes identified in previous studies of Atlantic Coastal Plain aquifers. Contrasts in groundwater chemistry between the Wilcox and the underlying McNairy and overlying Claiborne aquifers indicate that confining units are relatively effective in limiting cross-formational flow, but localized cross-formational mixing could occur via fault zones. Consequently, increased pumping in the vicinity of fault zones could facilitate upward movement of saline water into the Wilcox.

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

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.

Hydrologic monitoring of a waste-injection well near Milton, Florida, June 1975 - December 1976

USGS Publications Warehouse

Pascale, Charles A.; Martin, J.B.

1977-01-01

Hydraulic and chemical data were collected through a monitoring program conducted by the U.S. Geological Survey at an industrial liquid-waste injection site 6 mi southwest of Milton, Fla., in Santa Rosa County. The injection system is described. Data include injection rates, volumes, and pressures; water-level data at three monitor wells and a standby injection well, and field and laboratory analyses of water samples from four wells. Hydraulic and geochemical effects of the waste-injection system at the plant as of December 31, 1976, have been detected only in the injection zone, the lower limestone of the Floridan aquifer. Increased pressures are evident at the three wells used to monitor the injection zone. Geochemical changes have been noted only at the deep-test monitor well closest to the injection well. (Woodard-USGS)

Three-dimensional DFN Model Development and Calibration: A Case Study for Pahute Mesa, Nevada National Security Site

NASA Astrophysics Data System (ADS)

Pham, H. V.; Parashar, R.; Sund, N. L.; Pohlmann, K.

2017-12-01

Pahute Mesa, located in the north-western region of the Nevada National Security Site, is an area where numerous underground nuclear tests were conducted. The mesa contains several fractured aquifers that can potentially provide high permeability pathways for migration of radionuclides away from testing locations. The BULLION Forced-Gradient Experiment (FGE) conducted on Pahute Mesa injected and pumped solute and colloid tracers from a system of three wells for obtaining site-specific information about the transport of radionuclides in fractured rock aquifers. This study aims to develop reliable three-dimensional discrete fracture network (DFN) models to simulate the BULLION FGE as a means for computing realistic ranges of important parameters describing fractured rock. Multiple conceptual DFN models were developed using dfnWorks, a parallelized computational suite developed by Los Alamos National Laboratory, to simulate flow and conservative particle movement in subsurface fractured rocks downgradient from the BULLION test. The model domain is 100x200x100 m and includes the three tracer-test wells of the BULLION FGE and the Pahute Mesa Lava-flow aquifer. The model scenarios considered differ from each other in terms of boundary conditions and fracture density. For each conceptual model, a number of statistically equivalent fracture network realizations were generated using data from fracture characterization studies. We adopt the covariance matrix adaptation-evolution strategy (CMA-ES) as a global local stochastic derivative-free optimization method to calibrate the DFN models using groundwater levels and tracer breakthrough data obtained from the three wells. Models of fracture apertures based on fracture type and size are proposed and the values of apertures in each model are estimated during model calibration. The ranges of fracture aperture values resulting from this study are expected to enhance understanding of radionuclide transport in fractured rocks and support development of improved large-scale flow and transport models for Pahute Mesa.

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.

Geologic Controls of Hydraulic Conductivity in the Snake River Plain Aquifer At and Near the Idaho National Engineering and Environmental Laboratory, Idaho

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

S. R. Anderson; M. A. Kuntz; L. C. Davis

1999-02-01

The effective hydraulic conductivity of basalt and interbedded sediment that compose the Snake River Plain aquifer at and near the Idaho National Engineering and Environmental Laboratory (INEEL) ranges from about 1.0x10 -2 to 3.2x10 4 feet per day (ft/d). This six-order-of-magnitude range of hydraulic conductivity was estimated from single-well aquifer tests in 114 wells, and is attributed mainly to the physical characteristics and distribution of basalt flows and dikes. Hydraulic conductivity is greatest in thin pahoehoe flows and near-vent volcanic deposits. Hydraulic conductivity is least in flows and deposits cut by dikes. Estimates of hydraulic conductivity at and near themore » INEEL are similar to those measured in similar volcanic settings in Hawaii. The largest variety of rock types and the greatest range of hydraulic conductivity are in volcanic rift zones, which are characterized by numerous aligned volcanic vents and fissures related to underlying dikes. Three broad categories of hydraulic conductivity corresponding to six general types of geologic controls can be inferred from the distribution of wells and vent corridors. Hydraulic conductivity of basalt flows probably is increased by localized fissures and coarse mixtures of interbedded sediment, scoria, and basalt rubble. Hydraulic conductivity of basalt flows is decreased locally by abundant alteration minerals of probable hydrothermal origin. Hydraulic conductivity varies as much as six orders of magnitude in a single vent corridor and varies from three to five orders of magnitude within distances of 500 to 1,000 feet. Abrupt changes in hydraulic conductivity over short distances suggest the presence of preferential pathways and local barriers that may greatly affect the movement of ground water and the dispersion of radioactive and chemical wastes downgradient from points of waste disposal.« less

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.

Selenium(IV) and (VI) sorption by soils surrounding fly ash management facilities

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

Hyun, S.; Burns, P.E.; Murarka, I.

2006-11-15

Leachate derived from unlined coal ash disposal facilities is one of the most significant anthropogenic sources of selenium to the environment. To establish a practical framework for predicting transport of selenium in ash leachate, sorption of Se(IV) and Se(VI) from 1 mM CaSO{sub 4} was measured for 18 soils obtained down-gradient from three ash landfill sites and evaluated with respect to several soil properties. Furthermore, soil attenuation from lab-generated ash leachate and the effect of Ca{sup 2+} and SO{sub 4}{sup 2-} concentrations as well as pH on both Se(IV) and Se(VI) was quantified for a subset of soils. For bothmore » Se(IV) and Se(VI), pH combined with either percentage clay or dithionite-citrate-bicarbonate (DCB)-extractable Fe described {gt} 80% of the differences in sorption across all soils, yielding an easy approach for making initial predictions regarding site-specific selenium transport to sensitive water bodies. Se(IV) consistently exhibited an order of magnitude greater sorption than Se(VI). Selenium sorption was highest at lower pH values, with Se(IV) sorption decreasing at pH values above 6, whereas Se(VI) decreased over the entire pH range (2.5-10). Using these pH adsorption envelopes, the likely effect of ash leachate-induced changes in soil pore water pH with time on selenium attenuation by down gradient soils can be predicted. Selenium sorption increased with increasing Ca{sup 2+} concentrations while SO{sub 4}2- suppressed sorption well above enhancements by Ca{sup 2+}. Soil attenuation of selenium from ash leachates agreed well with sorption measured from 1 mM CaSO{sub 4}, indicating that 1 mM CaSO{sub 4} is a reasonable synthetic leachate for assessing selenium behavior at ash landfill sites.« less

Optimization of water-level monitoring networks in the eastern Snake River Plain aquifer using a kriging-based genetic algorithm method

USGS Publications Warehouse

Fisher, Jason C.

2013-01-01

Long-term groundwater monitoring networks can provide essential information for the planning and management of water resources. Budget constraints in water resource management agencies often mean a reduction in the number of observation wells included in a monitoring network. A network design tool, distributed as an R package, was developed to determine which wells to exclude from a monitoring network because they add little or no beneficial information. A kriging-based genetic algorithm method was used to optimize the monitoring network. The algorithm was used to find the set of wells whose removal leads to the smallest increase in the weighted sum of the (1) mean standard error at all nodes in the kriging grid where the water table is estimated, (2) root-mean-squared-error between the measured and estimated water-level elevation at the removed sites, (3) mean standard deviation of measurements across time at the removed sites, and (4) mean measurement error of wells in the reduced network. The solution to the optimization problem (the best wells to retain in the monitoring network) depends on the total number of wells removed; this number is a management decision. The network design tool was applied to optimize two observation well networks monitoring the water table of the eastern Snake River Plain aquifer, Idaho; these networks include the 2008 Federal-State Cooperative water-level monitoring network (Co-op network) with 166 observation wells, and the 2008 U.S. Geological Survey-Idaho National Laboratory water-level monitoring network (USGS-INL network) with 171 wells. Each water-level monitoring network was optimized five times: by removing (1) 10, (2) 20, (3) 40, (4) 60, and (5) 80 observation wells from the original network. An examination of the trade-offs associated with changes in the number of wells to remove indicates that 20 wells can be removed from the Co-op network with a relatively small degradation of the estimated water table map, and 40 wells can be removed from the USGS-INL network before the water table map degradation accelerates. The optimal network designs indicate the robustness of the network design tool. Observation wells were removed from high well-density areas of the network while retaining the spatial pattern of the existing water-table map.

Monitored Natural Attenuation of ino9rganic Contaminants Treatability Study Final Report

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

Crapse, K

2004-05-19

The identification and quantification of key natural attenuation processes for inorganic contaminants at D-Area is detailed herein. Two overarching goals of this evaluation of monitored natural attenuation (MNA) as a remediation strategy were (1) to better define the availability of inorganic contaminants as potential sources for transport to groundwater and uptake by environmental receptors and (2) to understand the site-specific mechanisms controlling attenuation of these inorganic contaminants through tandem geochemical and biological characterization. Data collected in this study provides input for more appropriate site groundwater transport models. Significant natural attenuation is occurring at D-Area as evidenced by relatively low aqueousmore » concentrations of constituents of concern (COCs) (Be, Ni, U, and As) at all locations characterized and the decrease in groundwater concentrations with increasing distance from the source. The observed magnitude of decrease in groundwater concentrations of COCs with distance from the D-Area Coal Pile Runoff Basin (DCPRB) could not be accounted for by the modeled physical attenuation processes of dilution/dispersion. This additional attenuation, i.e., the observed difference between the groundwater concentrations of COCs and the modeled physical attenuation, is due to biogeochemical processes occurring at the D-Area. In tandem geochemical and microbiological characterization studies designed to evaluate the mechanisms contributing to natural attenuation, pH was the single parameter found to be most predictive of contaminant attenuation. The increasing pH with distance from the source is likely responsible for increased sorption of COCs to soil surfaces within the aquifer at D-Area. Importantly, because the sediments appear to have a high buffering capacity, the acid emanating from the DCPRB has been neutralized by the soil, and these conditions have led to large Kd values at the site. Two major types of soils are present at D-Area and were evaluated in this study: upland subsurface soils associated with a low pH/high sulfate/metals plume down-gradient of the D-Area Coal Pile Runoff Basin (DCPRB) and surface ash material discharged to the wetland from the D-Area Ash Basin (488-D). Sequential extraction studies were carried out to better define the availability of inorganic contaminant sources at D-Area.« less

Processes affecting transport of uranium in a suboxic aquifer

USGS Publications Warehouse

Davis, J.A.; Curtis, G.P.; Wilkins, M.J.; Kohler, M.; Fox, P.; Naftz, D.L.; Lloyd, J.R.

2006-01-01

At the Naturita site in Colorado, USA, groundwaters were sampled and analyzed for chemical composition and by culture and culture-independent microbiological techniques. In addition, sediments were extracted with a dilute sodium carbonate solution to determine quantities of labile uranium within the sediments. Samples from the upgradient portion of the contaminated aquifer, where very little dissolved Fe(II) is found in the groundwater, have uranium content that is controlled by U(VI) adsorption and few metal-reducing bacteria are observed. In the extreme downgradient portion of the aquifer, where dissolved Fe(II) is observed, uranium content of the sediments includes significant quantities of reduced U(IV) and diverse populations of Fe(III)-reducing bacteria were present in the subsurface with the potential of reducing U(VI) to U(IV). ?? 2006 Elsevier Ltd. All rights reserved.

Completion Report for Well ER-20-12: Corrective Action Units 101 and 102: Central and Western Pahute Mesa

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

Wurtz, Jeff

2016-08-01

Well ER-20-12 was drilled for the U.S. Department of Energy, Nevada National Security Administration Nevada Field Office in support of the Underground Test Area Activity. The well was drilled from October 2015 to January 2016 as an addition to the Central and Western Pahute Mesa corrective action units 101 and 102 the Phase II drilling program. Well ER-20-12 was identified based on recommendations of the Pahute Mesa Guidance Team as a result of anomalous tritium detections in groundwater samples collected from Well PM-3 in 2011 and 2013. The primary purpose of the well was to provide information on the hydrogeologymore » in the area downgradient of select underground tests on Western Pahute Mesa and define hydraulic properties in the saturated Tertiary volcanic rocks. The main 46.99-centimeter (cm) (18.5-inch [in.]) borehole was drilled to a depth of 765.14 meters (m) (2,510.3 ft) and the hole opened to 66.04 cm (26 in.); followed by the 50.80-cm (20-in.) surface casing, which was installed and sealed with cement; and a piezometer (p4) was set in the Timber Mountain welded-tuff aquifer (TMWTA) between the casing and the open borehole. The borehole was continued with a 46.99-cm (18.5-in.) drill bit to a depth of 1,326.53 m (4,352.16 ft), and an intermediate 24.44-cm (9.625-in.) casing was installed and sealed to 1,188.72 m (3,900.00 ft) A piezometer (p3) was installed across the Calico Hills zeolitic composite unit (CHZCM) (lava-flow aquifer [LFA]) in the annulus of the open borehole. Two additional piezometers were installed and completed between the intermediate casing and the borehole wall, one (p2) in the CHZCM and one (p1) in the Belted Range aquifer (BRA). The piezometers are set to monitor groundwater properties in the completed intervals. The borehole was continued with a 21.59-cm (8.5-in.) drill bit to a total depth of 1,384.80 m (4,543.33 ft), and the main completion 13.97-cm (5.5-in.) casing was installed in the open borehole across the Pre-Belted Range composite unit (PBRCM). Data collected during hole construction include composite drill cutting samples collected every 3.0 m (10 ft), geophysical logs, hydrophysical logs, percussion core samples, water-quality measurements (including tritium), and water-level measurements. The well penetrated 1,384.4 m (4,543.33 ft) of Tertiary volcanic rocks. The stratigraphy and lithology were generally as expected with one noted exception. A thick lava-flow and related ash-flow tuffs were identified as Calico Hills Formation (Th), and no Crater Flat units were noted. Additionally, many of the Thirsty Canyon and Timber Mountain units were thicker than expected. Fluid levels measured in the borehole during drilling are the following: (1) on November 2, 2015, Navarro measured the fluid level in the borehole at a depth of 492.33 m (1,615.25 ft) below ground surface (bgs); (2) Schlumberger and COLOG recorded fluid levels during geophysical logging on November 4 and 5, 2015, at a depth of 492.86 m (1,617 ft) and 492.25 m (1,615 ft) bgs, respectively; and (3) on December 4, 2015, COLOG and Navarro measured fluid level in the 20-in. casing with an open borehole to 1,326.54 m (4,352.16 ft) bgs at 575.77 m (1,889.00 ft) and 574.03 m (1,883.3 ft) bgs, respectively. These and subsequent water-level measurements indicate a potential head difference of greater than 76.2 m (250 ft) for groundwater in aquifers above and below the Upper Paintbrush confining unit (UPCU). As expected, tritium was occasionally measured above the Safe Drinking Water Act limit (20,000 picocuries per liter [pCi/L]). Lab analysis on four bailed samples and taken from the undeveloped well indicate that the tritium activities average approximately 36,545 pCi/L. All Fluid Management Plan (FMP) requirements for Well ER-20-12 were met. Analysis of monitoring samples and FMP confirmatory samples indicate that fluids generated during drilling at ER-20-12 met the FMP criteria for discharge to the lined sump and designated infiltration area. All sanitary and hydrocarbon waste generated was properly handled and disposed of.« less

Appraisal of ground-water quality near wastewater-treatment facilities, Glacier National Park, Montana

USGS Publications Warehouse

Moreland, Joe A.; Wood, Wayne A.

1982-01-01

Water-level and water-quality data were collected from monitoring wells at wastewater-treatment facilities in Glacier National Park. Five additional shallow observation wells were installed at the Glacier Park Headquarters facility to monitor water quality in the shallow ground-water system.Water-level, water-quality, and geologic information indicate that some of the initial monitoring wells are not ideally located to sample ground water most likely to be affected by waste disposal at the sites. Small differences in chemical characteristics between samples from monitor wells indicate that effluent may be affecting ground-water quality but that impacts are not significant.Future monitoring of ground-water quality could be limited to selected wells most likely to be impacted by percolating effluent. Laboratory analyses for common ions could detect future impacts.

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

LaFreniere, L. M.; Environmental Science Division

On September 7, 2005, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) presented a Scoping Memo (Argonne 2005) for preliminary consideration by the Kansas Department of Health and Environment (KDHE), suggesting possible remedial options for the carbon tetrachloride contamination in groundwater at Everest, Kansas. The suggested approaches were discussed by representatives of the KDHE, the CCC/USDA, and Argonne at the KDHE office in Topeka on September 8-9, 2005, along with other technical and logistic issues related to the Everest site. In response to these discussions, the KDHE recommended (KDHE 2005) evaluation of several remedial processes, either alonemore » or in combination, as part of a Corrective Action Study (CAS) for Everest. The primary remedial processes suggested by the KDHE were the following: Hydraulic control by groundwater extraction with aboveground treatment; Air sparging (AS) coupled with soil vapor extraction (SVE) in large-diameter boreholes (LDBs); and Phytoremediation. As a further outcome of the 2005 meeting and as a precursor to development of a possible CAS, the CCC/USDA completed the following supplemental investigations at Everest to address several specific technical concerns discussed with the KDHE: (1) Construction of interpretive cross sections at strategic locations selected by the KDHE along the main plume migration pathway, to depict the hydrogeologic characteristics affecting groundwater flow and contaminant movement (Argonne 2006a). (2) A field investigation in early 2006 (Argonne 2006b), as follows: (a) Installation and testing of a production well and associated observation points, at locations approved by the KDHE, to determine the response of the Everest aquifer to groundwater extraction near the Nigh property. (b) Groundwater sampling for the analysis of volatile organic compounds (VOCs) and the installation of additional permanent monitoring points at locations selected by the KDHE, to further constrain the existing contaminant plume. (c) Resampling of all existing permanent monitoring points for VOCs and biodegradation parameter analyses, at the request of the KDHE. On the basis of these studies (Argonne 2006a,b) and the CCC/USDA's past investigations at Everest (Argonne 2006c), the CCC/USDA concluded that groundwater extraction is not an effective remedial option for the main body of the groundwater plume, and the KDHE concurred (KDHE 2006); the KDHE later noted, however (KDHE 2007a), that this and other technologies might represent viable remedial options in the event of further downgradient migration of the plume toward the intermittent creek. In February 2007, the CCC/USDA presented preliminary analyses of (1) the AS-SVE remedial alternative, incorporating the use of LDBs, and (2) the risks to human health and the environment posed by the observed carbon tetrachloride plume in groundwater (Argonne 2007a). The results of these analyses demonstrated the following: (1) Neither groundwater extraction nor AS-SVE in LDBs represents a practical approach for effective remediation of the groundwater contamination at Everest (near the Nigh property). (2) Periodic sampling and analyses for VOCs conducted by the CCC/USDA documented that the areal extent and range of carbon tetrachloride concentrations detected in the groundwater plume at Everest had changed relatively little from 2000 to 2006. (3) Estimates of groundwater flow and contaminant migration times, based on the hydrogeologic properties of the groundwater flow system identified at Everest (Argonne 2003, 2006b,c), indicated that, at minimum, approximately 4 years would be required for the carbon tetrachloride plume (in the subsurface) to reach the vicinity of the intermittent creek directly west of the Nigh property, and more than 20 years would be required for the contamination to reach the identified groundwater discharge area southwest of the Nigh property. (4) The existing (January-March 2006) plume posed no immediate danger of contamination to the surface waters of the intermittent creek. In light of these observations, the CCC/USDA proposed a phased program--over approximately 2-3 years--of groundwater sampling, surface water sampling, and related monitoring activities at Everest to (1) identify locations where a phytoremediation system would be effective and determine that area's extent and (2) support the potential development of a phytoremediation treatment alternative for the site. The recommended elements of the monitoring program are summarized in Table 1.1. In conjunction with this program, both the CCC/USDA and the KDHE recommended the construction of several new monitoring wells, at locations along and near the intermittent creek west of the Nigh property (Argonne 2007b; KDHE 2007b).« less

Groundwater monitoring well assessment final work plan

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

Not Available

1993-10-01

Jacobs Engineering Group Inc. (JEG) has been contracted by Environmental Management Operations (EMO) to develop and implement a Groundwater Monitoring Well Assessment Plan for Canal Creek in the Edgewood Area of Aberdeen Proving Ground (APG-EA). The task will be performed under the provisions of Master Agreement 071914-A-D7, Task Order 142133. The project consists of assessing the condition of existing groundwater monitoring wells in the Canal Creek Area prior to a groundwater sampling program. The following Work Plan describes the technical approach that will be used to conduct field work for the project. Integrity of some monitoring wells installed at APG-EAmore » has come into question because of problems with well completions that were detected in wells at the O-field Study Area during a recent sampling event. Because of this, EPA and APG-DSHE officials have requested a well integrity assessment for a percentage of 168 monitoring wells installed at the Canal Creek Study Area(14 by USATHAMA, 152 by USGS). Results of the well assessment will be used to determine if these wells were completed in a fashion that minimizes the potential for either cross-contamination of aquifers or leakage of water from the surface into the well.« less

Monitoring of subsurface injection of wastes, Florida

USGS Publications Warehouse

Vecchioli, John

1979-01-01

Injection of waste liquids into Florida's subsurface is physically feasible in many places but should be accompanied by monitoring of the waste-receiving aquifer system in addition to the injection facility. Monitoring of the interaction of factors including hydrogeologic conditions, well construction, waste volumes and characteristics, and potable-water sources is desirable to assure that fresh-water resources are not being adversely affected. An effective aquifer-system monitoring program includes on-site wells located close to an injection well and open to the next-higher permeable stratum, satellite wells located hundreds to several thousands of feet from an injection well and open to the receiving aquifer, and regional wells located miles from individual injection wells and open to the receiving aquifer. An extensive aquifer-system monitoring program associated with two waste-injection facilities near Pensacola, Florida, has provided data which have aided hydrologists to understand the aquifer system's response to the injection and, accordingly, to evaluate the potential for affecting the area's fresh-water resources.

PASSIVE SAMPLING OF GROUND WATER MONITORING WELLS WITHOUT PURGING MULTILEVEL WELL CHEMISTRY AND TRACER DISAPPEARANCE

EPA Science Inventory

It is essential that the sampling techniques utilized in groundwater monitoring provide data that accurately depicts the water quality of the sampled aquifer in the vicinity of the well. Due to the large amount of monitoring activity currently underway in the U.S.A. it is also im...

Gulf Coast geopressured-geothermal program summary report compilation. Volume 2-B: Resource description, program history, wells tested, university and company based research, site restoration

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

John, C.J.; Maciasz, G.; Harder, B.J.

1998-06-01

The US Department of Energy established a geopressured-geothermal energy program in the mid 1970`s as one response to America`s need to develop alternate energy resources in view of the increasing dependence on imported fossil fuel energy. This program continued for 17 years and approximately two hundred million dollars were expended for various types of research and well testing to thoroughly investigate this alternative energy source. This volume describes the following studies: Design well program; LaFourche Crossing; MG-T/DOE Amoco Fee No. 1 (Sweet Lake); Environmental monitoring at Sweet Lake; Air quality; Water quality; Microseismic monitoring; Subsidence; Dow/DOE L.R. Sweezy No. 1more » well; Reservoir testing; Environmental monitoring at Parcperdue; Air monitoring; Water runoff; Groundwater; Microseismic events; Subsidence; Environmental consideration at site; Gladys McCall No. 1 well; Test results of Gladys McCall; Hydrocarbons in production gas and brine; Environmental monitoring at the Gladys McCall site; Pleasant Bayou No. 2 well; Pleasant Bayou hybrid power system; Environmental monitoring at Pleasant Bayou; and Plug abandonment and well site restoration of three geopressured-geothermal test sites. 197 figs., 64 tabs.« less

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.

Analysis of trace neptunium in the vicinity of underground nuclear tests at the Nevada National Security Site.

PubMed

Zhao, P; Tinnacher, R M; Zavarin, M; Kersting, A B

2014-11-01

A high sensitivity analytical method for (237)Np analysis was developed and applied to groundwater samples from the Nevada National Security Site (NNSS) using short-lived (239)Np as a yield tracer and HR magnetic sector ICP-MS. The (237)Np concentrations in the vicinity of the Almendro, Cambric, Dalhart, Cheshire, and Chancellor underground nuclear test locations range from <4 × 10(-4) to 2.6 mBq/L (6 × 10(-17)-4.2 × 10(-13) mol/L). All measured (237)Np concentrations are well below the drinking water maximum contaminant level for alpha emitters identified by the U.S. EPA (560 mBq/L). Nevertheless, (237)Np remains an important indicator for radionuclide transport rates at the NNSS. Retardation factor ratios were used to compare the mobility of (237)Np to that of other radionuclides. The results suggest that (237)Np is less mobile than tritium and other non-sorbing radionuclides ((14)C, (36)Cl, (99)Tc and (129)I) as expected. Surprisingly, (237)Np and plutonium ((239,240)Pu) retardation factors are very similar. It is possible that Np(IV) exists under mildly reducing groundwater conditions and exhibits a retardation behavior that is comparable to Pu(IV). Independent of the underlying process, (237)Np is migrating downgradient from NNSS underground nuclear tests at very low but measureable concentrations. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

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.

Uncertainties related to the representation of momentum transport in shallow convection

NASA Astrophysics Data System (ADS)

Schlemmer, Linda; Bechtold, Peter; Sandu, Irina; Ahlgrimm, Maike

2017-04-01

The vertical transport of horizontal momentum by convection has an important impact on the general circulation of the atmosphere as well as on the life cycle and track of cyclones. So far convective momentum transport (CMT) has mostly been studied for deep convection, whereas little is known about its characteristics and importance in shallow convection. In this study CMT by shallow convection is investigated by analyzing both data from large-eddy simulations (LES) and simulations performed with the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). In addition, the central terms underlying the bulk mass-flux parametrization of CMT are evaluated offline. Further, the uncertainties related to the representation of CMT are explored by running the stochastically perturbed parametrizations (SPP) approach of the IFS. The analyzed cases exhibit shallow convective clouds developing within considerable low-level wind shear. Analysis of the momentum fluxes in the LES data reveals significant momentum transport by the convection in both cases, which is directed down-gradient despite substantial organization of the cloud field. A detailed inspection of the convection parametrization reveals a very good representation of the entrainment and detrainment rates and an appropriate representation of the convective mass and momentum fluxes. To determine the correct values of mass-flux and in-cloud momentum at the cloud base in the parametrization yet remains challenging. The spread in convection-related quantities generated by the SPP is reasonable and addresses many of the identified uncertainties.

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.

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

Effective contaminant detection networks in uncertain groundwater flow fields.

PubMed

Hudak, P F

2001-01-01

A mass transport simulation model tested seven contaminant detection-monitoring networks under a 40 degrees range of groundwater flow directions. Each monitoring network contained five wells located 40 m from a rectangular landfill. The 40-m distance (lag) was measured in different directions, depending upon the strategy used to design a particular monitoring network. Lagging the wells parallel to the central flow path was more effective than alternative design strategies. Other strategies allowed higher percentages of leaks to migrate between monitoring wells. Results of this study suggest that centrally lagged groundwater monitoring networks perform most effectively in uncertain groundwater-flow fields.

Numerical Simulation of Borehole Flow in Deep Monitor Wells, Pearl Harbor Aquifer, Oahu, Hawaii

NASA Astrophysics Data System (ADS)

Rotzoll, K.; Oki, D. S.; El-Kadi, A. I.

2010-12-01

Salinity profiles collected from uncased deep monitor wells are commonly used to monitor freshwater-lens thickness in coastal aquifers. However, vertical flow in these wells can cause the measured salinity to differ from salinity in the adjacent aquifer. Substantial borehole flow has been observed in uncased wells in the Pearl Harbor aquifer, Oahu, Hawaii. A numerical modeling approach, incorporating aquifer hydraulic characteristics and recharge rates representative of the Pearl Harbor aquifer, was used to evaluate the effects of borehole flow on measured salinity profiles from deep monitor wells. Borehole flow caused by vertical hydraulic gradients associated with the natural regional groundwater-flow system and local groundwater withdrawals was simulated. Model results were used to estimate differences between vertical salinity profiles in deep monitor wells and the adjacent aquifer in areas of downward, horizontal, and upward flow within the regional flow system—for cases with and without nearby pumped wells. Aquifer heterogeneity, represented in the model as layers of contrasting permeability, was incorporated in model scenarios. Results from this study provide insight into the magnitude of the differences between vertical salinity profiles from deep monitor wells and the salinity distributions in the aquifers. These insights are relevant and are critically needed for management and predictive modeling purposes.

The Savannah River Site`s groundwater monitoring program. Third quarter 1990

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

Not Available

1991-05-06

The Environmental Protection Department/Environmental Monitoring Section (EPD/EMS) administers the Savannah River Site`s (SRS) Groundwater Monitoring Program. During third quarter 1990 (July through September) EPD/EMS conducted routine sampling of monitoring wells and drinking water locations. EPD/EMS established two sets of flagging criteria in 1986 to assist in the management of sample results. The flagging criteria do not define contamination levels; instead they aid personnel in sample scheduling, interpretation of data, and trend identification. The flagging criteria are based on detection limits, background levels in SRS groundwater, and drinking water standards. All analytical results from third quarter 1990 are listed in thismore » report, which is distributed to all site custodians. One or more analytes exceeded Flag 2 in 87 monitoring well series. Analytes exceeded Flat 2 for the first since 1984 in 14 monitoring well series. In addition to groundwater monitoring, EPD/EMS collected drinking water samples from SRS drinking water systems supplied by wells. The drinking water samples were analyzed for radioactive constituents.« less

The Savannah River Site's groundwater monitoring program

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

Not Available

1991-05-06

The Environmental Protection Department/Environmental Monitoring Section (EPD/EMS) administers the Savannah River Site's (SRS) Groundwater Monitoring Program. During third quarter 1990 (July through September) EPD/EMS conducted routine sampling of monitoring wells and drinking water locations. EPD/EMS established two sets of flagging criteria in 1986 to assist in the management of sample results. The flagging criteria do not define contamination levels; instead they aid personnel in sample scheduling, interpretation of data, and trend identification. The flagging criteria are based on detection limits, background levels in SRS groundwater, and drinking water standards. All analytical results from third quarter 1990 are listed in thismore » report, which is distributed to all site custodians. One or more analytes exceeded Flag 2 in 87 monitoring well series. Analytes exceeded Flat 2 for the first since 1984 in 14 monitoring well series. In addition to groundwater monitoring, EPD/EMS collected drinking water samples from SRS drinking water systems supplied by wells. The drinking water samples were analyzed for radioactive constituents.« less

Use of Low-Cost Acquisition Systems with an Embedded Linux Device for Volcanic Monitoring

PubMed Central

Moure, David; Torres, Pedro; Casas, Benito; Toma, Daniel; Blanco, María José; Del Río, Joaquín; Manuel, Antoni

2015-01-01

This paper describes the development of a low-cost multiparameter acquisition system for volcanic monitoring that is applicable to gravimetry and geodesy, as well as to the visual monitoring of volcanic activity. The acquisition system was developed using a System on a Chip (SoC) Broadcom BCM2835 Linux operating system (based on DebianTM) that allows for the construction of a complete monitoring system offering multiple possibilities for storage, data-processing, configuration, and the real-time monitoring of volcanic activity. This multiparametric acquisition system was developed with a software environment, as well as with different hardware modules designed for each parameter to be monitored. The device presented here has been used and validated under different scenarios for monitoring ocean tides, ground deformation, and gravity, as well as for monitoring with images the island of Tenerife and ground deformation on the island of El Hierro. PMID:26295394

Use of Low-Cost Acquisition Systems with an Embedded Linux Device for Volcanic Monitoring.

PubMed

Moure, David; Torres, Pedro; Casas, Benito; Toma, Daniel; Blanco, María José; Del Río, Joaquín; Manuel, Antoni

2015-08-19

This paper describes the development of a low-cost multiparameter acquisition system for volcanic monitoring that is applicable to gravimetry and geodesy, as well as to the visual monitoring of volcanic activity. The acquisition system was developed using a System on a Chip (SoC) Broadcom BCM2835 Linux operating system (based on DebianTM) that allows for the construction of a complete monitoring system offering multiple possibilities for storage, data-processing, configuration, and the real-time monitoring of volcanic activity. This multiparametric acquisition system was developed with a software environment, as well as with different hardware modules designed for each parameter to be monitored. The device presented here has been used and validated under different scenarios for monitoring ocean tides, ground deformation, and gravity, as well as for monitoring with images the island of Tenerife and ground deformation on the island of El Hierro.

Map of the approximate inland extent of saltwater at the base of the Biscayne aquifer in the Model Land Area of Miami-Dade County, Florida, 2016

USGS Publications Warehouse

Prinos, Scott T.

2017-07-11

The inland extent of saltwater at the base of the Biscayne aquifer in the Model Land Area of Miami-Dade County, Florida, was mapped in 2011. Since that time, the saltwater interface has continued to move inland. The interface is near several active well fields; therefore, an updated approximation of the inland extent of saltwater and an improved understanding of the rate of movement of the saltwater interface are necessary. A geographic information system was used to create a map using the data collected by the organizations that monitor water salinity in this area. An average rate of saltwater interface movement of 140 meters per year was estimated by dividing the distance between two monitoring wells (TPGW-7L and Sec34-MW-02-FS) by the travel time. The travel time was determined by estimating the dates of arrival of the saltwater interface at the wells and computing the difference. This estimate assumes that the interface is traveling east to west between the two monitoring wells. Although monitoring is spatially limited in this area and some of the wells are not ideally designed for salinity monitoring, the monitoring network in this area is improving in spatial distribution and most of the new wells are well designed for salinity monitoring. The approximation of the inland extent of the saltwater interface and the estimated rate of movement of the interface are dependent on existing data. Improved estimates could be obtained by installing uniformly designed monitoring wells in systematic transects extending landward of the advancing saltwater interface.

Compound-specific isotope analysis: Questioning the origins of a trichloroethene plume

USGS Publications Warehouse

Eberts, S.M.; Braun, C.; Jones, S.

2008-01-01

Stable carbon isotope ratios of trichloroethene (TCE), cis-1,2- dichloroethene, and trans-1,2-dichloroethene were determined by use of gas chromatography-combustion-isotope ratio mass spectroscopy to determine whether compound-specific stable carbon isotopes could be used to help understand the origin and history of a TCE groundwater plume in Fort Worth, TX. Calculated ??13C values for total chlorinated ethenes in groundwater samples, which can approximate the ??13C of a spilled solvent if all degradation products are accounted for, were useful for determining whether separate lobes of the plume resulted from different sources. Most notably, values for one lobe, where tetrachloroethene (PCE) has been detected periodically, were outside the range for manufactured TCE but within the range for manufactured PCE, whereas values for a separate lobe, which is downgradient of reported TCE spills, were within the range for manufactured TCE. Copyright ?? Taylor & Francis Group, LLC.