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At least 19 records

Anthropogenic Markers in Alta Irrigation District Water Supply Wells

In July 2016, LLNL produced a report for the Kings River Watershed Coalition Authority (KRWCA) entitled “Groundwater Age and Nitrate Isotopic Composition in Alta Irrigation District Water Supply Wells” (Esser et al., 2016). That report summarized groundwater age and nitrate isotopic composition data produced by LLNL for Alta Irrigation District (AID) groundwater wells sampled by KRWCA in a pilot project to test the utility of advanced isotopic methods for constraining the timing and source of nitrate in groundwater at selected sites in the Kings River service area. One section of that report made recommendations for follow-on study. The first and strongest recommendation was to measure a wider suite of source tracers including co-contaminants such as herbicides, pesticides, pharmaceuticals, personal care products, and food constituents and additives. KRWCA followed up on this recommendation in Phase II of the pilot study by re-sampling the original set of wells and submitting the samples to a commercial laboratory for analysis of a limited range of co-contaminants (including pharmaceuticals, personal care products , and food constituents and additives, but not including herbicides or pesticides). They have asked that LLNL review and interpret these data in the context of previous LLNL analyses and to evaluate the utility of such co-contaminant analyses in providing additional constraints on the source of groundwater nitrate contamination in Alta Irrigation District water supply wells. The goal of the second phase of this pilot project is to evaluate the utility of co-contaminant occurrence for constraining nitrate source in groundwater at selected sites in the Kings River service area, with special reference to the use of such data in conjunction with advanced isotopic methods such as nitrate isotopic composition and groundwater age. Nitrate isotopic composition alone cannot distinguish nitrate derived from animal manure from nitrate derived from human septic waste. The presence or absence of agricultural chemicals (herbicides, pesticides, veterinary pharmaceuticals) or chemicals associated with people (human pharmaceuticals, artificial sweeteners) can help make this distinction. Co-contaminant analyses using multi-analyte LC-MS-MS protocols are now commercially available and reasonably priced. The feasibility and utility of the using co-contaminants for nitrate source attribution can be evaluated by 1) determining the degree to which co-contaminants occur in distinct and easily attributable groupings (e.g. agricultural chemicals vs personal care products and food additives); 2) determining the degree to which co-contaminant occurrence is consistent with nitrate isotopic composition and groundwater age (e.g. no co-contaminant occurrence in very old groundwater; co-contaminants consistent with animal manure or human septic waste occurring in groundwaters having nitrate isotopic composition also consistent with animal manure or human septic waste); and 3) determining the degree to which co-contaminants provide additional constraint on nitrate source over and beyond nitrate isotopic composition and groundwater age (e.g. distinguishing between animal manure and human septic waste).

58 GEOSCIENCES↗

Cr(VI) Occurrence and Geochemistry in Water From Public-Supply Wells in California

Hexavalent chromium, Cr(VI), in 918 wells sampled throughout California between 2004 and 2012 by the Groundwater Ambient Monitoring and Assessment Program—Priority Basin Project (GAMA—PBP) ranged from less than the study reporting limit (SRL) of 1 microgram per liter (μg/L) to 32 μg/L. Statewide, Cr(VI) was reported in 31 percent of sampled wells and equaled or exceeded the recently established (2014) California Maximum Contaminant Level (MCL) for Cr(VI) of 10 μg/L in 4 percent of sampled wells. Cr(VI) data collected for regulatory purposes overestimate Cr(VI) occurrence. Ninety percent of chromium was present as Cr(VI), which was detected more frequently and at higher concentrations in alkaline (pH > 8), oxic water, and more frequently in agricultural and urban land uses compared to native land uses. Chemical, isotopic (tritium and carbon-14), and noble-gas data show high Cr(VI) in water from wells in alluvial aquifers in the southern California deserts result from long groundwater-residence times and geochemical reactions such as silicate weathering that increase pH, while oxic conditions persist. High Cr(VI) in water from wells in alluvial aquifers along the west-side of the Central Valley results from high-chromium abundance in source rock eroded to form those aquifers, and areal recharge processes (including irrigation return) that mobilize chromium from the unsaturated zone. Cr(VI) co-occurred with oxyanions having similar chemistry, including vanadium, selenium, and uranium. Cr(VI) was positively correlated with nitrate, consistent with increased concentrations in areas of agricultural land use and mobilization of chromium from the unsaturated zone by irrigation return.

54 ENVIRONMENTAL SCIENCES↗

Sitewide monitoring at Agra, Kansas, June 2011

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. Other public wells, outside the area of contamination, supply drinking water for the city of Agra. Both PWS-3 and PWS-4 remain available for uses other than drinking water.

LaFreniere, L. M.↗

CY2019 Annual Closure Monitoring Report for Corrective Action Unit 98, Frenchman Flat, Underground Test Area, Nevada National Security Site, Nevada (January 2019–December 2019), Revision 1

Three types of monitoring are performed for CAU 98: water quality, water level, and institutional control. These are monitored to determine whether the URs remain protective of human health and the environment, and to ensure that the regulatory boundary objectives are being met. Monitoring data will be used in the future, once multiple years of data are available, to evaluate consistency with the groundwater flow and contaminant transport models because the contaminant boundaries calculated with the models are the primary basis of the UR boundaries. Six wells were sampled for water-quality monitoring in 2019. Contaminants of concern were detected only in the two source/plume wells already known to contain contamination as a result of a radionuclide migration experiment. Tritium concentrations in both of these wells, RNM-2S and UE-5n, remain above the Safe Drinking Water Act maximum contaminant level of 20,000 picocuries per liter but declined in 2019 as compared to measurements in 2018. All other contaminants of concern are below the minimum detection level plus analytical error. The water-level monitoring network includes 16 wells. Depth to water measured in 2019 is generally consistent with recent measurements for all wells. Many wells continue to exhibit a long-term downward trend in water level, though changes from 2018 to 2019 are minimal. The sharp 2016 decline in water level in Well ER-5-3-2 remains unexplained, with the lower level persisting through 2019. Rising water-level trends continue to be observed in Well ER-5-3 deep piezometer and former water supply Well WW-5A. Water supply Well WW-5B experienced a rise in water level as a result of an absence of pumping in the first part of the year (due to a mechanical problem), whereas water levels declined in WW-4 and WW-4A in response to greater pumping in 2019. Institutional control monitoring confirmed the URs are recorded in U.S. Department of Energy and U.S. Air Force land management systems, and that no activities within Frenchman Flat basin are occurring that could potentially affect the contaminant boundaries. Survey of groundwater resources in basins surrounding Frenchman Flat similarly identify no current or pending development that would indicate the need to increase monitoring activities or would otherwise cause concern for the closure decision. The URs continue to prevent exposure of the public, workers, and the environment to contaminants of concern by preventing use of potentially contaminated groundwater.

54 ENVIRONMENTAL SCIENCES↗

CY2018 Annual Closure Monitoring Report for Corrective Action Unit 98, Frenchman Flat, Underground Test Area, Nevada National Security Site, Nevada (January 2018–December 2018, Revision 1)

Corrective Action Unit (CAU) 98: Frenchman Flat on the Nevada National Security Site was the location of 10 underground nuclear tests. CAU 98 underwent a series of investigations and actions in accordance with the Federal Facility Agreement and Consent Order to assess contamination of groundwater by radionuclides from the tests. A Closure Report completed that process in 2016 and called for long-term monitoring, use restrictions (URs), and institutional controls to protect the public and environment from potential exposure to contaminated groundwater. Three types of monitoring are performed for CAU 98: water quality, water level, and institutional control. These are monitored to determine whether the URs remain protective of human health and the environment, and to ensure that the regulatory boundary objectives are being met. Monitoring data will be used in the future, once multiple years of data are available, to evaluate consistency with the groundwater flow and contaminant transport models because the contaminant boundaries calculated with the models are the primary basis of the UR boundaries. Six wells were sampled for water-quality monitoring in 2018. Contaminants of concern were detected only in the two source/plume wells already known to contain contamination as a result of a radionuclide migration experiment. Tritium concentrations in both of these wells, RNM-2S and UE-5n, remain above the Safe Drinking Water Act maximum contaminant level of 20,000 picocuries per liter but declined in 2018 as compared to measurements in 2017. All other contaminants of concern are below the minimum detection level plus analytical error. The water-level monitoring network includes 16 wells. Depth to water measured in 2018 is generally consistent with recent measurements for all wells. Many wells continue to exhibit a long-term downward trend in water level, despite small increases in measured water levels in 2018. The sharp 2016 decline in water level in Well ER-5-3-2 remains unexplained, with the lower level persisting through 2018. Rising water-level trends continue to be observed in two relatively deep wells (ER-5-3 deep piezometer and ER-5-4-2), and also in former supply Well WW-5A. The current supply wells exhibit relatively erratic water levels associated with pumping activities. Institutional control monitoring confirmed the URs are recorded in U.S. Department of Energy and U.S. Air Force land management systems, and that no activities within Frenchman Flat basin are occurring that could potentially affect the contaminant boundaries. Survey of groundwater resources in basins surrounding Frenchman Flat similarly identify no current or pending development that would indicate the need to increase monitoring activities or would otherwise cause concern for the closure decision. The URs continue to prevent exposure of the public, workers, and the environment to contaminants of concern by preventing use of potentially contaminated groundwater.

54 ENVIRONMENTAL SCIENCES↗

Annual Report of Monitoring at Morrill, Kansas, in 2013

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 public water supply 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. Because the identified carbon tetrachloride contamination in groundwater could potentially be linked, in part, to historical use of carbon tetrachloride-based fumigants at its former facility, in 2003 the CCC/USDA assumed responsibility for 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. That investigation and subsequent investigations were performed by the Environmental Science Division of Argonne National Laboratory. The initial investigation by the CCC/USDA in 2003 determined that soils at the former facility were not impacted by grain fumigation activities. Neither carbon tetrachloride nor chloroform (the primary degradation product of carbon tetrachloride) was detected in nearsurface soils or in subsurface soils collected to bedrock. Because no identifiable human health risk was associated with either carbon tetrachloride or chloroform in shallow soils, the conclusion was that no further threat of contamination to groundwater was present. In September 2005, the CCC/USDA initiated periodic sampling of groundwater, in accord with a program approved by the KDHE (2005), to monitor carbon tetrachloride concentrations in the groundwater. The report presents the data generated during the 2013 monitoring period.

54 ENVIRONMENTAL SCIENCES↗

Annual Report of Monitoring at Barnes, Kansas, in 2015

This present report documents the results of monitoring conducted in 2015. Sampling of the approved monitoring well network and the two public water supply wells was conducted on October 1-5, 2015.

54 ENVIRONMENTAL SCIENCES↗

Utah FORGE: Groundwater Data

This submission includes two modeled drawdown scenarios with new supply well locations, a total dissolved solids (TDS) concentration grid (raster dataset representing the spatial distribution of TDS), and an excel spreadsheet containing well data.

15 GEOTHERMAL ENERGY↗

Model-assisted decision analyses related to a chromium plume at Los Alamos national Laboratory - 15449

?he chromium plume at Los Alamos National Laboratory is a complex contaminant-remediation site with spatial extent of several square kilometers. It is located in a regional aquifer near water-supply wells and other points of compliance. The plume originated on the ground surface and the contaminant migrated along complex pathways through a thick vadose zone (∼300 m) that includes intermediate lateral zones of saturation and vertical preferential flow paths. Here we discuss the development of a modeling computational framework for the site. The framework work incorporates data assimilation and model-results analysis tools including decision support techniques. The decision tools are demonstrated using synthetic problems consistent with the interpretation of existing site data and site modeling results. The analyses aim at robust and efficient environmental management of the plume and explore a series of alternative remedial options. The remedial options include natural attenuation (NA), enhanced attenuation (EA), contaminant source removal (in the vadose zone), contaminant extraction (in the regional aquifer at the plume centroid and peripheries), biogeochemical remediation (injection of fluids stimulating growth of organisms in the aquifer impacting chromium concentrations), as wells as hydraulic controls on the groundwater flow and transport in the vadose zone and the regional aquifer. The applied model analyses and decision-support algorithms are implemented in code MADS (Model Analyses for Decision Support; http://mads.lanl.gov). MADS is an open-source framework for model-based decision support employing system and physics simulation models. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Review of Time-Series Data for the Agra Interim Measure, Fall 2013

The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) operated a grain storage facility at Agra, Kansas, from the 1950s to the early 1970s. No structures remain on the property, and the land is used for agricultural purposes, specifically wheat production. The property is currently owned by the Kyle Railroad Co. and is leased to Mr. Herb VanEaton. The Pro-Ag Marketing grain storage facility is directly south of the former CCC/USDA facility. In 1985, carbon tetrachloride was detected in groundwater samples collected from Agra public water supply wells PWS-3 and PWS-4, located approximately 2,000 ft south of the former CCC/USDA facility and approximately 1,800 ft south of the Pro-Ag Marketing Facility, at levels below the maximum contaminant level of 5.0 μg/L. In 1986, in response to an increase in carbon tetrachloride to 12 μg/L in well PWS-3, the city was required to remove both PWS-3 and PWS-4 from service. The Agra public water supply system is served by three other wells (PWS-1, PWS-2, and PWS-5) that are outside the area of contamination. In 2005, the Environmental Science Division of Argonne National Laboratory conducted a comprehensive investigation of potential contaminant source areas at Agra, on behalf of the CCC/USDA. Data collected during the 2005 investigation identified three primary source areas for the carbon tetrachloride contamination (Argonne 2006). One source is located on the former CCC/USDA property, and the other two sources are on property owned by Pro-Ag Marketing. In 2008-2009, to address the carbon tetrachloride contamination detected on its former property, the CCC/USDA initiated source area cleanup as an interim measure (IM) in accord with the document Interim Measure Work Plan/Design for Agra, Kansas (IMWP/D; Argonne 2008). The cleanup employs five large-diameter boreholes (LDBs) that were excavated by auger drilling. The purposes of these borings were to (1) physically remove soils impacted by carbon tetrachloride from the most contaminated area for treatment by onsite land farming and (2) provide locations for the installation of coupled soil vapor extraction (SVE) and air sparging (AS) wells to facilitate in situ treatment of the remaining carbon tetrachloride in the soils and groundwater. Construction data for the SVE wells, the AS wells, and groundwater and soil gas observation points installed to monitor the progress of the cleanup (as reported on the Kansas Review of Time-Series Data for the Agra Interim Measure 1-2 Version 01, 10/24/13 WWC-5 forms for these installations) are summarized in Table 1.1. The locations of the wells are shown in Figure 1.1. The IMWP/D was approved by the Kansas Department of Health and Environment in November 2008 (KDHE 2008), and operation of the SVE/AS systems began in May 2009. With the approval of the KDHE (2009), landfarming operations to treat the contaminated soils excavated from the LDBs were completed on October 12, 2010. Since start-up, the IM activities have been documented periodically (Argonne 2009a,b,c; Argonne 2010a,b,c,d, 2011a,b,c, 2012, 2013a,b), in accord with the requirements of the KDHEapproved IMWP/D (Argonne 2008). Each of the reports primarily summarizes the operations and maintenance of the SVE and AS equipment and the results of sampling of the groundwater, soil gas, and system effluents for analyses for volatile organic compounds (VOCs) over a specific 3- to 6-month period. Hence, the focus is the incremental performance of the IM. To complement these documents, this report provides a broader perspective by examining the collective data acquired since start-up on May 29, 2009, and through June 2013. The objectives of this approach are to evaluate possible longer-term trends in (1) the operational characteristics of the remedial systems and (2) the corresponding responses in the subsurface environment and their potential relationships to the progress of the cleanup. To facilitate this investigation, time-series diagrams have been developed to illustrate key parameter data for the SVE and AS systems, as well as sampling and additional supporting data obtained from the monitoring program. An overview of the information compiled is in Section 2. In Section 3, observations drawn from these data are discussed. The principal findings of the evaluation and recommendations for consideration are summarized in Sections 4 and 5, respectively.

54 ENVIRONMENTAL SCIENCES↗

Southeast Carbon Sequestration Partnership (SECARB) Phase III Anthropogenic Test at Citronelle Field, Mobile Co., AL Surface and Shallow Subsurface Monitoring

The Southeast Carbon Sequestration Partnership Phase III Anthropogenic Test at Citronelle Field is one of the United States’ largest demonstrations of CO 2 capture, transportation, injection, storage and monitoring using CO 2 derived from a coal-fired electric generating unit. This report summarizes the background and initial injection phase groundwater and soil flux monitoring results. The purpose of the groundwater monitoring program, as prescribed in the Underground Injection Control (UIC) permits is to assure that the project’s activities do not harm Underground Sources of Drinking Water (USDWs). In particular, the objective of the program is to monitor for the release of injected CO2 into groundwater aquifers at the project site. Three shallow USDW monitoring wells were installed as part of the groundwater monitoring program. In addition, a water supply well located near the project’s deep characterization well was utilized for monitoring. Seventeen metals, general chemistry and field parameters (e.g. pH, specific conductance, turbidity) were sampled three times prior to injection and quarterly during the injection period to date. Changes in groundwater geochemistry potentially attributable to a release of carbon dioxide into the USDW from the injection activities are decreasing pH and increasing TIC. The change in pH may also accompany the mobilization of certain metals within the groundwater, but the changes are likely site-specific, based on the natural aquifer mineralogy (Wilkin and Diguilio, 2010). At this time, no downward trends for pH and increasing trends for TIC have been statistically determined in the monitor wells. Valid detections exceeding both the UIC discharge limit and the range of background concentrations observed as of the N=11 event include: Exceedance of the UIC permit discharge limit of manganese at D-9-7 MW-2S and D-9-9 MW-1, and exceedance of the UIC permit discharge limit of iron at D-9-9 MW-1. In addition, a statistically significant increase of barium and manganese has been observed at D-9-9 MW-1. However, Additional lines of evidence (namely, expected shifts in TIC or pH, per the research cited above) to interpret the cause (e.g., potential carbon dioxide influence) of the statistically determined exceedances and/or increases are absent at this time. Quarterly groundwater sampling and analysis will continue throughout the project. The UIC permit requires that soil CO 2 flux shall be monitored at the land surface at the injection site and at nearby locations. Twelve locations were chosen for surveys including a mix of near wellbore and offset locations. To date, 24 surveys have taken place with 12 occurring prior to the onset of injection operations in August 2012. Soil CO 2 flux appears to positively covary with soil temperature. A notably high soil CO 2 flux value (21 µmol/m 2 /sec) was observed from the D-9-9 #2 chamber location during sampling event #24 (9/24/2014). As a result of this finding, the frequency of soil CO 2 flux monitoring events will be increased to twice-monthly until this anomaly can be confirmed or determined to be an outlier. Soil CO 2 flux monitoring will continue for the duration of the project.

01 COAL, LIGNITE, AND PEAT↗

Integrated solid-state rapid thermo-cycling system

Techniques, systems, and devices are disclosed for implementing a portable lab system for PCR testing. An example method for operating an integrated thermal cycling system includes depositing samples into the integrated thermal cycling system that includes a thermal cycling device and an electronic interface. The thermal cycling device includes multiple wells to receive the samples to be thermally cycled, a thermoelectric cooling (TEC) element connected to the multiple wells, a substrate on which the TEC element is positioned, and a controller coupled to the TEC element. The multiple wells are positioned within the substrate that includes a thermally conductive ground positioned between adjacent wells. Supplying power to the integrated thermal cycling system, via the electronic interface, allows the multiple wells to exchange heat with the substrate and for each well to operate independently from other wells.

Beer, N. Reginald↗

Annual Closure Monitoring Report for Corrective Action Unit 98, Frenchman Flat, Underground Test Area, Nevada National Security Site, Nevada: (CY2017 January 2017–December 2017, Rev. 0)

Corrective Action Unit (CAU) 98: Frenchman Flat on the Nevada National Security Site was the location of 10 underground nuclear tests. CAU 98 underwent a series of investigations and actions in accordance with the Federal Facility Agreement and Consent Order to assess contamination of groundwater by radionuclides from the tests. A Closure Report completed that process in 2016 and called for long-term monitoring, use restrictions (URs), and institutional controls to protect the public and environment from potential exposure to contaminated groundwater. Three types of monitoring are performed for CAU 98: water quality, water level, and institutional control. These are monitored to determine whether the URs remain protective of human health and the environment, and to ensure that the regulatory boundary objectives are being met. Monitoring data will be used in the future, once multiple years of data are available, to evaluate consistency with the groundwater flow and contaminant transport models because the contaminant boundaries calculated with the models are the primary basis of the UR boundaries. Six wells were sampled for water-quality monitoring in 2017. Contaminants of concern were detected only in the two source/plume wells already known to contain contamination as a result of a radionuclide migration experiment. The 86,000-picocuries-per-liter (pCi/L) tritium concentration in one of the wells is about 12 percent higher than measured in 2016 but is over an order of magnitude less than the peak value measured in the well in 1980. The concentration in the other source/plume well is lower than measured in 2016. The water-level monitoring network includes 16 wells. Depth to water measured in 2017 is generally consistent with recent measurements for most wells. Water-level declines differing from long-term trends were observed in four wells. Three of these (WW-4, WW-4A, and WW-5B) are water-supply wells that experienced increases in pumping during the year. No definitive cause for the sharp decline in the fourth well (ER-5-3-2) in 2016 is known as yet. Institutional control monitoring confirmed the URs are recorded in U.S. Department of Energy and U.S. Air Force land management systems, and that no activities within Frenchman Flat basin are occurring that could potentially affect the contaminant boundaries. Survey of groundwater resources in basins surrounding Frenchman Flat similarly identify no current or pending development that would indicate the need to increase monitoring activities or would otherwise cause concern for the closure decision. The URs continue to prevent exposure of the public, workers, and the environment to contaminants of concern by preventing use of potentially contaminated groundwater.

54 ENVIRONMENTAL SCIENCES↗

Site Investigation Results, 2009-2011, Inman, Kansas (Final Report)

The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) operated a grain storage facility at the southern edge of the city of Inman, Kansas, from 1954 to 1965. During this time, commercial grain fumigants containing carbon tetrachloride were in common use by the grain storage industry to preserve grain in their facilities. In 1997, trace to low levels of carbon tetrachloride (below the maximum contamination level [MCL] of 5.0 µg/L) were detected in three private wells near the former grain storage facility at Inman, as part of a statewide USDA private well sampling program that was implemented by the Kansas Department of Health and Environment (KDHE) near former CCC/USDA facilities. No public water supply wells were identified in 1998 by the KDHE within 1 mi of the town. Carbon tetrachloride is the contaminant of primary concern at sites associated with grain storage operations. To determine whether the former CCC/USDA facility at Inman is a potential contaminant source and its possible relationship to the contamination in groundwater, the CCC/USDA agreed to conduct investigations at Inman. The investigations were performed by the Environmental Science Division of Argonne National Laboratory in accordance with the Intergovernmental Agreement between the KDHE and the Farm Service Agency of the USDA. Argonne, on behalf of the CCC/USDA, developed a Work Plan (Argonne 2007) and subsequently a Summary of Investigation Results and Proposed Work Plan (Appendix A) for a phased site investigation. The proposed work was approved by the KDHE (2007, 2011). The investigations were conducted from November 2009 to September 2011, as proposed in the two work plans. This report presents the findings of the 2009-2011 investigations at Inman.

54 ENVIRONMENTAL SCIENCES↗

FInal Report: Site Investigation Results, 2009-2011, at Inman, Kansas

The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) operated a grain storage facility at the southern edge of the city of Inman, Kansas, from 1954 to 1965. During this time, commercial grain fumigants containing carbon tetrachloride were in common use by the grain storage industry to preserve grain in their facilities. In 1997, trace to low levels of carbon tetrachloride (below the maximum contamination level [MCL] of 5.0 μg/L) were detected in three private wells near the former grain storage facility at Inman, as part of a statewide USDA private well sampling program that was implemented by the Kansas Department of Health and Environment (KDHE) near former CCC/USDA facilities. No public water supply wells were identified in 1998 by the KDHE within 1 mi of the town. Carbon tetrachloride is the contaminant of primary concern at sites associated with grain storage operations. To determine whether the former CCC/USDA facility at Inman is a potential contaminant source and its possible relationship to the contamination in groundwater, the CCC/USDA agreed to conduct investigations at Inman. The investigations were performed by the Environmental Science Division of Argonne National Laboratory in accordance with the Intergovernmental Agreement between the KDHE and the Farm Service Agency of the USDA. Argonne, on behalf of the CCC/USDA, developed a Work Plan (Argonne 2007) and subsequently a Summary of Investigation Results and Proposed Work Plan (Appendix A) for a phased site investigation. The proposed work was approved by the KDHE (2007, 2011). The investigations were conducted from November 2009 to September 2011, as proposed in the two work plans. This report presents the findings of the 2009-2011 investigations at Inman.

54 ENVIRONMENTAL SCIENCES↗

Final Monitoring Plan for Site Closure at Inman, Kansas

Inman, Kansas, is a rural town located in southwest McPherson County, in sections 8, 9, 16, and 17, Township 21 South, Range 4 West (Figure 1.1). There are 1,377 people in 513 households, as of the census of 2010. The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA), operated a grain storage facility at the southern edge of the city of Inman, Kansas, from 1954 to 1965. During this time, commercial grain fumigants containing carbon tetrachloride were in common use by the grain storage industry to preserve grain in their facilities. In 1997, trace to low levels of carbon tetrachloride (below the maximum contamination level [MCL] of 5.0 μg/L) were detected in three private wells near the former grain storage facility at Inman, as part of a statewide USDA private well sampling program that was implemented by the Kansas Department of Health and Environment (KDHE) near former CCC/USDA facilities. No public water supply wells were identified within 1 mi of the town by the KDHE in 1998. Carbon tetrachloride is the contaminant of primary concern at sites associated with grain storage operations. To determine whether the former CCC/USDA facility at Inman is a potential contaminant source and its possible relationship to the carbon tetrachloride contamination in groundwater, the CCC/USDA agreed to conduct a multi-phase investigation at Inman. The investigation was performed by the Environmental Science Division of Argonne National Laboratory in accordance with the Intergovernmental Agreement between the KDHE and the Farm Service Agency of the USDA.

54 ENVIRONMENTAL SCIENCES↗

Hexavalent Chromium Sources and Distribution in California Groundwater

Groundwater resources in California represent a confluence of high-risk factors for hexavalent chromium contamination as a result of industrial activities, natural geology, and, potentially, land use. Here, we examine state-wide links in California between groundwater Cr(VI) concentrations and chemicals that provide signatures for source attribution. In environmental monitoring wells, Cr(VI) had the highest co-occurrence and also clustered with 1,4-dioxane and several chlorinated hydrocarbons indicative of the metal plating industry. Additionally, hotspots of Cr(VI) co-occurring with bromoform result from volatile organic compound remediation using in situ chemical oxidation that inadvertently oxidizes naturally occurring Cr(III). In groundwater supply wells, which are typically free of industrial inputs, Cr(VI) correlates with dichlorodiphenyldichloroethylene (DDE), vanadium, and ammonia and clusters with nitrate and dissolved oxygen, suggesting potential links between agricultural activities and Cr(VI). Specific controls on Cr(VI) vary substantially by region: from the metal plating industry around Los Angeles and the San Francisco Bay areas to natural redox conditions along flow paths in the Mojave Desert and to correlations with agricultural practices in the Central Valley of California. Here, while industrial uses of Cr lead to the most acute cases of groundwater Cr(VI) contamination, oxidation of naturally occurring Cr affects a larger area, more wells, and a greater number of people throughout California.

54 ENVIRONMENTAL SCIENCES↗