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To Read About . . . See Page . . .

Groundwater at SRS 107. . . . . . . . . . . . . . . . . . . Description of Groundwater Monitoring Program 120. . . . . . . . . . . . . . . . . . . Groundwater Monitoring Program Changes During 2001 121. . . . . . . . . . . . . . . . . Groundwater Monitoring Results 121. . . . . . . .

Chapter 8

GroundwaterJohn ReedEnvironmental Protection Department

Bob HiergesellEnvironmental Sciences and Technology

Jen WilliamsExR, Inc.

URING the past 40 years, scientists havebegun to understand the complexity of thehydrologic system. Water on the land surface

and in the atmosphere is easily studied, but waterexisting in pores and fractures beneath the surface isless accessible. Water infiltrates into soils and rockbeneath the ground, then moves along pressuregradients—sometimes for short distances beforeemerging in streams and lakes; sometimes acrosshundreds of miles over many years. While water in asurface stream may flow many miles in a day,groundwater may move only a few hundred feet in ayear.

As scientists have come to understand thephenomenon of groundwater, they have come toappreciate the risks that come from contaminationfinding its way into this dynamic system. During the20th century, waste from industrial and publicactivities was discovered in groundwater, andscientists found that cleaning water underground wasmuch more difficult than removing contaminantsfrom surface water. As a result, federal and stategovernments enacted statutes designed to protect thegroundwater and to clean up contamination found ingroundwater. Understanding, using, protecting, andcleaning up groundwater are significant aspects of theSavannah River Site (SRS) groundwater program.

SRS is located atop sediments of the Atlantic CoastalPlain composed predominantly of sand and clay.Water flows easily through the sand layers but isretarded by less permeable clay beds, creating acomplex system of aquifers. Operations during thelife of SRS have resulted in contamination migratinginto groundwater at various locations on the site(figure 8–1), predominantly in the central areas of thesite. The ongoing movement of water into the ground,through the aquifer system, and then into streams andlakes—or even into deeper aquifers—continues tocarry contamination along with it, resulting inspreading plumes.

To address this problem, the site has developed, overseveral decades, a comprehensive network ofmonitoring wells that have helped SRS scientistsunderstand the physical groundwater system, locateplumes of contamination in groundwater, and monitorthe progress of cleanup efforts. In addition tomonitoring, the site has a comprehensivegroundwater protection and remediation program thatwill be described later in this chapter. The chapteralso will describe SRS’s physical groundwatersystem; its monitoring, protection, and remediationprograms; and—in summary form—the monitoringresults.

This chapter provides an overview of thegroundwater monitoring program at SRS; moredetailed groundwater monitoring results can beobtained by contacting the manager of theWestinghouse Savannah River Company (WSRC)Environmental Protection Department (EPD) at803–725–1728.

The Environmental Protection Department’s WellInventory (ESH–EMS–2000–470), which is availableto the public, contains detailed maps of the wells ateach monitored location.

Groundwater at SRSSRS is underlain by sediment of the Atlantic CoastalPlain. The Atlantic Coastal Plain consists of asoutheast-dipping wedge of unconsolidated sedimentthat extends from its contact with the PiedmontProvince at the Fall Line to the edge of thecontinental shelf. The sediment ranges from LateCretaceous to Miocene in age and comprises layers ofsand, muddy sand, and clay with subordinatecalcareous sediments. It rests on crystalline andsedimentary basement rock.

The hydrostratigraphy of SRS has been subject toseveral classifications. The hydrostratigraphicclassification established in Aadland et al., 1995, andin Smits et al., 1996, is widely used at SRS and is

D

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SRTC/ER Map

Figure 8–1 Facilities Monitored by the SRS Monitoring Well Network; Shaded Areas Indicate Extent ofGroundwater Contamination in 2001.

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A-Area/M-Area� A-Area/M-Area Recovery Well Network� A-Area Background Well Near Firing Range� A-Area Burning/Rubble Pits/A-Area Ash Pile� A-Area Coal Pile Runoff Containment Basin� A-Area Metals Burning Pit� A–014 Outfall� M-Area Hazardous Waste Management Facility

& M-Area Plume Definition� Metallurgical Laboratory Seepage Basin� Miscellaneous Chemical Basin� Motor Shop Oil Basin� Savannah River Laboratory Seepage Basins� Silverton Road Waste Site

General Separations/Waste Management (E-Area, F-Area, H-Area, S-Area, & Z-Area)� Burial Grounds Perimeter� Burma Road Rubble Pit� E-Area Vaults near the Burial Grounds� F-Area Ash Basin� F-Area Burning/Rubble Pits� F-Area Canyon Building/A-Line Uranium

Recovery Facility� F-Area Coal Pile Runoff Containment Basin� F-Area Effluent Treatment Cooling Water Basin� F-Area Retention Basins� F-Area Sanitary Sludge L& Application Site� F-Area Seepage Basins/Inactive Process Sewer Line� F-Area Seepage Basins Remediation Extraction Wells/

Tank� F-Area Seepage Basins Remediation Injection Wells/

Tank� F-Area Tank Farm� H-Area Auxiliary Pump Pit� H-Area Canyon Building� H-Area Coal Pile Runoff Containment Basin� H-Area Effluent Treatment Cooling Water Basin� H-Area Retention Basins� H-Area Seepage Basins/Inactive Process Sewer Line� H-Area Seepage Basins Remediation Extraction Wells

& Tank� H-Area Seepage Basins Remediation Injection Wells &

Tank� H-Area Tank Farm/Tank Farm Groundwater Operable

Unit� Hazardous Waste/Mixed Waste Disposal Facility� HP-52 Outfall/Warner’s Pond Area� Old Burial Ground� Old F-Area Seepage Basin� Old H-Area Retention Basin� S-Area Defense Waste Processing Facility� S-Area Low-Point Pump Pit� S-Area Vitrification Building� Waste Solidification/Disposal Facility� Wells Between the F-Area Canyon Building & the

Naval Fuel Material Facility� Z-Area Low-Point Drain Tank� Z-Area Saltstone Facility Background Wells

C-Area� C-Area Burning/Rubble Pit� C-Area Coal Pile Runoff Containment Basin� C-Area Disassembly Basin� C-Area Reactor Seepage Basins� Injection Wells of the C-Area Reactor

K-Area� K-Area Ash Basin� K-Area Bingham Pump Outage Pit� K-Area Burning/Rubble Pit� K-Area Coal Pile Runoff Containment Basin� K-Area Disassembly Basin� K-Area Reactor Seepage Basin� K-Area Retention Basin� K-Area Tritium Sump

L-Area� Chemicals, Metals, & Pesticides Pits� L-Area Acid/Caustic Basin/L-Area Oil

& Chemical Basin� L-Area Bingham Pump Outage Pits� L-Area Burning/Rubble Pit� L-Area Disassembly Basin� L-Area Reactor Seepage Basin� L-Area Research Wells

P-Area� P-Area Bingham Pump Outage Pit� P-Area Burning/Rubble Pit� P-Area Coal Pile Runoff Containment Basin� P-Area Disassembly Basin� P-Area Reactor Seepage Basins

R-Area� R-Area Acid/Caustic Basin� R-Area Bingham Pump Outage Pit� R-Area Burning/Rubble Pits� R-Area Coal Pile� R-Area Disassembly Basin� R-Area Reactor Seepage Basins

Sanitary Landfill & B-Area� B-Area Microbiology Wells� Sanitary Landfill/Interim Sanitary Landfill

Central Shops (N-Area)� Ford Building Seepage Basin� Hazardous Waste Storage Facility� Hydrofluoric Acid Spill� N-Area Diesel Spill� N-Area Burning/Rubble Pits� N-Area (Central Shops) Sludge Lagoon� N-Area Fire Department Training Facility� N-Area Heavy Equipment Wash Basin and Burning/

Rubble Pit

D-Area & TNX-Area� D-Area Burning/Rubble Pits� D-Area Oil Seepage Basin� D-Area Coal Pile, Coal Pile Runoff Containment

Basin, & Ash Basins� New/Old TNX Seepage Basins� Road A Chemical Basin (Baxley Road)� TNX-Area Assessment Wells� TNX-Area Background Wells� TNX-Area Points along Seepline� TNX-Area Operable Unit Wells� TNX-Area Floodplain Wells� TNX-Area Recovery Wells� TNX Burying Ground� TNX Intrinsic Remediation Piezometers� TNX Permeable Wall Demonstration Well Installation� TNX Outfall Delta

Other Sites� Accelerator for Production of Tritium Area� SREL Flowing Springs Site

Key for Figure 8–1

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regarded as the current SRS standard. This system isconsistent with the one used by the U.S. GeologicalSurvey (USGS) in regional studies that include thearea surrounding SRS [Clarke and West, 1997].Figure 8–2 is a chart that indicates the relativeposition of hydrostratigraphic units and relateshydrostratigraphic units to corresponding lithologicunits at SRS and to the geologic time scale. This chartwas modified from Aadland et al., 1995, and Fallawand Price, 1995.

The hydrostratigraphic units of primary interestbeneath SRS are part of the Southeastern CoastalPlain Hydrogeologic Province. Within this sequenceof aquifers and confining units are two principalsubcategories, the overlying Floridan Aquifer Systemand the underlying Dublin-Midville Aquifer System.These systems are separated from one another by theMeyers Branch Confining System. In turn, each ofthe systems is subdivided into two aquifers, which areseparated by a confining unit.

In the central to southern portion of SRS, the FloridanAquifer System is divided into the overlying UpperThree Runs Aquifer and the underlying GordonAquifer, which are separated by the GordonConfining Unit. North of Upper Three Runs Creek,these units are collectively referred to as the SteedPond Aquifer, in which the Upper Three RunsAquifer is called the M-Area Aquifer zone, theGordon Aquifer is referred to as the Lost LakeAquifer zone, and the aquitard that separates them isreferred to as the Green Clay confining zone[Aadland et al., 1995]. The Upper Three RunsAquifer/Steed Pond Aquifer is the hydrostratigraphicunit within which the water table usually occurs atSRS; hence, it is informally referred to as the “watertable” aquifer.

The Dublin-Midville Aquifer System is divided intothe overlying Crouch Branch Aquifer and theunderlying McQueen Branch Aquifer, which areseparated by the McQueen Branch Confining Unit.The Crouch Branch Aquifer and McQueen BranchAquifer are names that originated at SRS [Aadland etal., 1995]. These units are equivalent to the DublinAquifer and the Midville Aquifer, which are namesoriginating with the USGS [Clarke and West, 1997].

Figure 8–3 is a three-dimensional block diagram ofthe hydrogeologic units at SRS and the generalizedgroundwater flow patterns within those units. Theseunits are from shallowest to deepest: the Upper ThreeRuns/Steed Pond Aquifer (or water table aquifer), theGordon/Lost Lake Aquifer, the Crouch BranchAquifer, and the McQueen Branch Aquifer.

Groundwater recharge is a result of the infiltration ofprecipitation at the land surface; the precipitationmoves vertically downward through the unsaturatedzone to the water table. Upon entering the saturatedzone at the water table, water moves predominantlyin a horizontal direction toward local discharge zonesalong the headwaters and midsections of streams,while some of the water moves into successivelydeeper aquifers. The water lost to successively deeperaquifers also migrates laterally within those unitstoward the more distant regional discharge zones.These typically are located along the major streamsand rivers in the area, such as the Savannah River.Groundwater movement within these units isextremely slow when compared to surface water flowrates. Groundwater velocities also are quite differentbetween aquitards and aquifers, ranging at SRS fromseveral inches to several feet per year in aquitards andfrom tens to hundreds of feet per year in aquifers.

Potentiometric contour maps for this report werecontoured using 2000 data. An exception is theCrouch Branch Aquifer; its contours were updatedduring 2001 based on measurements in new wells inthe northwestern part of the site and offsite wells nearJackson, South Carolina. However, the currentpotentiometric surfaces of the aquifers are notsignificantly different from those depicted in maps inthis report.

Figure 8–4 illustrates the water table configuration atSRS for second quarter 2000; the contours wereinitially taken from the SRS long-term mean watertable configuration [Hiergesell, 1998]. Water levelmeasurements obtained in second quarter 2000 thenwere posted on this map and contours then wereadjusted to be consistent with time-specificmeasurements. Horizontal groundwater movement inthe water table aquifer is in a direction that isperpendicular to the contours, proceeding from areasof higher fluid potential (recharge areas) to areas oflower fluid potential, where it discharges along thereaches of perennial streams at SRS.

The potentiometric level contours for theGordon/Lost Lake Aquifer, Crouch Branch Aquifer,and McQueen Branch Aquifer are illustrated infigures 8–5, 8–6, and 8–7, respectively. Thesecontours are based on water level measurementsobtained from SRS regional cluster wells in secondquarter 2000; however, additional water levelmeasurements obtained from monitoring wells alsowere used to construct the Gordon/Lost Lake Aquifercontours in A-Area, M-Area, and the generalseparations area of SRS. As with the water table,horizontal groundwater movement is in a directionperpendicular to the contours and proceeds from

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Modified from Aadland et al, 1995, and Fallaw and Price, 1995

Figure 8–2 Hydrostratigraphic Units at SRS

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Figure 8–3 Groundwater at SRSThe groundwater flow system at SRS consists of fourmajor aquifers separated by confining units. Flow inrecharge areas generally migrates downward as wellas laterally—eventually either discharging into theSavannah River and its tributaries or migrating intothe deeper regional flow system.

Modified from Clarke and West, 1997

areas of higher fluid potential to areas of lower fluidpotential.

Monitoring wells are used extensively at SRS toassess the effect of site activities on groundwaterquality. Most of the wells monitor the uppergroundwater zone, although wells in lower zones arepresent at the sites with the larger groundwatercontamination plumes. Groundwater in areasindicated on figure 8–1 contains one or moreconstituents at or above the levels of the DWS of theU.S. Environmental Protection Agency (EPA).

Groundwater ProtectionProgram at SRS

The SRS groundwater program was audited by boththe U.S. Department of Energy (DOE) and WSRC

during 2000 and 2001. Findings of these assessmentsresulted in the early revision of the site GroundwaterProtection Management Program Plan (GPMP;WSRC–TR–2001–00379) to codify improvements tothe program. The GPMP described five functionelements of the SRS program that are designed tomeet federal and state laws and regulations, DOEorders, and site policies and procedures. Theseelements include

� investigating site groundwater

� using site groundwater

� protecting site groundwater

� remediating contaminated groundwater

� reporting the results of these efforts tostakeholders

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SRTC/EST Map

Figure 8–4 Water Table Contours at SRS

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SRTC/EST Map

Figure 8–5 Potentiometric Surface of the Gordon Aquifer at SRS

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SRTC/EST Map

Figure 8–6 Potentiometric Surface of the Crouch Branch Aquifer at SRS

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SRTC/EST Map

Figure 8–7 Potentiometric Surface of the McQueen Branch Aquifer at SRS

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SRS identified specific program goals in each ofthese areas to maintain its commitment to agroundwater program that protects human health andthe environment. Groundwater monitoring is a keytool used in each of the first four elements, andmonitoring results form the basis for evaluations thatare reported to site stakeholders.

Investigating SRS Groundwater

An extensive program is in place at SRS to acquirenew data and information on the groundwater system.This program is multifaceted and is conducted acrossdepartmental boundaries at the site because of thedifferent charters and mandates of theseorganizations. Investigations include both thecollection and analysis of data to understandgroundwater conditions on regional and local scalesat SRS. Research efforts at the site generally areconducted to obtain a better understanding ofsubsurface processes and mechanisms or to definenew approaches to subsurface remediation.

Investigative efforts focus on the collection andanalysis of data to characterize the groundwater flowsystem. Characterization efforts at SRS include thefollowing activities:

� the collection of geologic core material and theperforming of seismic profiles to better delineatesubsurface structural features

� the installation of wells to allow the periodiccollection of both water levels and groundwatersamples at strategic locations

� the development of water table andpotentiometric maps to delineate the direction ofgroundwater movement in the subsurface

� the performance of various types of tests toobtain in situ estimates of hydraulic parametersneeded to estimate groundwater velocities

Analysis of data on the regional scale is needed toprovide a broad understanding of groundwatermovement patterns at SRS that can be used as aframework to better understand the migration ofcontaminants at the local scale near individual wasteunits. Surface water flow characteristics also aredefined at the site on the regional scale and aresignificant to risk analyses because perennial streamsare the receptors of groundwater discharge—some ofwhich contains contaminants from SRS waste units.Because the site boundary does not represent agroundwater boundary, regional studies are helpful inunderstanding the movement of groundwater bothonto the site from the surrounding area and viceversa.

The collection and analysis of data describingsubsurface hydrogeologic conditions at or nearindividual waste units is needed to design effectiveremediation systems. Characterization embraces bothtraditional and innovative technologies to accomplishthis goal. The installation of monitoring wells andpiezometers is a traditional investigative method toallow the collection of (1) water levels, which areused to define flow directions, and (2) groundwatersamples, which are analyzed to monitor contaminantplume migration within the groundwater flow system.Electric logs acquired during well installation areused to delineate the subsurface hydrostratigraphy.Examples of newer technologies include the use of

� direct-push technology, such as the conepenetrometer, to collect one-time groundwatersamples at investigation sites and to helpestablish hydrostratigraphic contacts

� the “rotosonic” method for bore holes to collectcore and install wells

Various tests are also conducted, as needed, to obtainin situ estimates of subsurface hydraulic propertiesthat can be used to calculate groundwater velocities.

Numerical models have been used extensively as ananalytical tool at SRS for both regional- andlocal-scale investigations. Models have been utilizedfor a variety of reasons, but primarily to (1) definethe regional groundwater movement patterns at SRSand the surrounding areas, (2) enhance theunderstanding of contaminant migration in thesubsurface, and (3) support the design of remediationsystems. At SRS, major groundwater modelingefforts have focused on A/M-Area, F-Area, H-Area,the Burial Ground Complex, and several of thereactor areas where the most extensive subsurfacecontamination is known to exist.

Research on groundwater issues is conducted at SRSto obtain a better understanding of subsurfacemechanisms, such as (1) the interaction ofcontaminants with the porous media matrix, and (2)the factors that impact the rate of migration ofcontaminants within the groundwater flow system.Research to address relevant issues often is conductedthrough cooperative studies with investigators atvarious public universities and private companies,while other efforts are conducted exclusively by SRSemployees.

Using SRS Groundwater

SRS derives its own drinking and production watersupply from groundwater. The site ranks as SouthCarolina’s largest self-supplied industrial consumerof groundwater, utilizing approximately 5.3 million

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gallons per day. SRS domestic and process watersystems are supplied from a network ofapproximately 40 site groundwater wells in widelyscattered locations across the site, of which eightsupply the primary drinking water system for the site.Treated well water is supplied to the larger sitefacilities by the A-Area, D-Area and K-Areadomestic water systems. Each system has wells, atreatment plant, elevated storage tanks, anddistribution piping. The wells range in capacity from200 to 1,500 gallons per minute.

These three systems supply an average of 1.1 milliongallons per day of domestic water to customers inthese areas. The domestic water systems supply sitedrinking fountains, lunchrooms, restrooms, andshowering facilities with water meeting state andfederal drinking water quality standards. Processwater is used for equipment cooling, facilitywashdown water, and as makeup water for sitecooling towers and production processes.

The South Carolina Department of Health andEnvironmental Control (SCDHEC) periodicallysamples the large- and small-system wells for SafeDrinking Water Act contaminants. An unscheduledbiannual SCDHEC sanitary survey also is performed.

In 1983, SRS began reporting its water usageannually to the South Carolina Water ResourcesCommission (and later to SCDHEC). Since that time,the amount of groundwater pumped on site hasdropped by 50 percent—from 10.8 million gallonsper day during 1983–1986 to 5.3 million gallons perday during 1997–2000. The majority of this decreaseis attributable to the consolidation of site domesticwater systems, which was completed in 1997.Thirteen separate systems, each with its own supplywells, were consolidated into three systems located inA-Area, D-Area, and K-Area. Site facility shutdownsand reductions in population were also contributingfactors. The amount of groundwater pumped at SRShas had only localized effects on water levels in theCretaceous aquifers, and it is unlikely that waterusage at the site ever will cause drawdown problemsthat could impact surrounding communities.

The process water systems in A-Area, F-Area,H-Area, K-Area, L-Area, S-Area and TNX-Areameet site demands for boiler feedwater, equipmentcooling water, facility washdown water, and makeupwater for cooling towers, fire storage tanks,chilled-water-piping loops, and site test facilities.These systems are supplied from dedicated processwater wells ranging in capacity from 100 to 1,500gallons per minute. In K-Area, the process watersystem is supplied from the domestic water wells. At

some locations, the process water wells pump toground-level storage tanks, where the water is treatedfor corrosion control. At other locations the wellsdirectly pressurize the process water distributionpiping system without supplemental treatment.

The site groundwater protection program integratesinformation learned about the properties of SRSaquifers with site demand for drinking and processwater. SRS ensures a high level of drinking watersupply protection by performing (1) monitoringabove and beyond SCDHEC monitoring and (2)periodic evaluations of production wells. Additionalprotection will be realized under a site wellheadprotection program that meets the requirements of theSouth Carolina Source Water Assessment Programdescribed below.

Protecting SRS GroundwaterSRS is committed to protecting the groundwaterresource beneath the site. A variety of activitiescontribute to this goal, including

� construction, waste management, and monitoringefforts to prevent or control sources ofgroundwater contamination

� monitoring programs (both groundwater andsurface water) to detect contamination

� a strong groundwater cleanup program throughthe Environmental Restoration Division (ERD)

Monitoring provides the best means to detect andtrack groundwater contamination. To ensure that nounknown contamination poses a risk, SRS dependson a sitewide groundwater monitoring and protectioneffort—the site Groundwater SurveillanceMonitoring Program (GSMP). This new program isan upgraded replacement of the site screeningprogram.

Because aquifer conditions and groundwater qualityvary in the temporal domain, an ongoing groundwatersurveillance monitoring program is a fundamentalpart of any groundwater protection effort. SRS iscontinually improving its surveillance program,which meshes with the regulatory program thataddresses contaminated groundwater.

Whereas the remediation monitoring program isperformed for the purpose of regulatory compliance(e.g., defining contamination in a hazardous wastemanagement facility or solid waste management unit,assessing the effectiveness of corrective action, etc.),the GSMP addresses sitewide groundwater protectionin accordance with DOE Order 5400.1, “GeneralEnvironmental Protection Program.”

One goal of the GSMP is to protect potential offsitereceptors from contamination by detecting

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contamination in time to apply appropriate correctiveactions. SRS is a large site, and most groundwatercontamination is located in the central site areas(figure 8–1). However, the potential for offsitemigration exists, and the consequences of such anoutcome are serious enough to warrant acomprehensive prevention program.

SRS has evaluated groundwater flow and determined,for each aquifer, where groundwater flows across thesite boundary, since the location of groundwater flowwould be a conservative surrogate for any potentialcontaminant migration. Monitoring at those locationsis being strengthened by the addition of several newwell clusters to ensure early detection of anycontamination migrating toward the site boundary. Ifcontamination is ever detected, appropriate reportingand remediation efforts can be initiated by DOE.

Another pathway for existing groundwatercontamination to flow offsite is by discharge intosurface streams and subsequent transport into theSavannah River. SRS monitors site streams forcontamination, and new wells have been installed inrecent years along several site streams to detectcontamination before it enters the stream and toassess its concentration in groundwater.

Another function of the groundwater protectionprogram is to monitor groundwater around operatingfacilities to ensure that any potential contaminationemanating from any facility is detected in a timelymanner. This monitoring includes the tank farms andcanyon facilities in the central site area. In addition,surveillance monitoring is performed at various wellsaround the site to detect any new or previouslyundetected contaminant plumes.

A major challenge of the site groundwater program isthe careful evaluation of the hundreds of thousands ofnew data records generated each year. The GSMPincludes analysis using a combination of newcomputer automation tools and “hands on”groundwater expertise to screen all the recent recordsin the site groundwater database each year. Thisevaluation seeks unexpected results in any site wellsthat might indicate new or changing groundwatercontamination.

SRS is cooperating with SCDHEC to develop andimplement source water assessment and protectionprograms. After an assessment program has beenapproved and implemented, the SRS groundwaterprotection program will focus on protection efforts.The primary aspect of the source water assessmentand protection programs will be wellhead protection,given that SRS derives its drinking water exclusively

from groundwater. Other aspects will includestrategies for preventing contamination andcontrolling existing contamination through the SRSprogram. The program will evaluate wasteminimization, spill prevention and control, wellabandonment, and future land use. More informationabout this initiative can be found athttp//www.epa.gov/safewater/protect.html.

Remediating Contaminated SRSGroundwater

SRS has maintained an environmental restorationeffort for many years. ERD personnel managegroundwater cleanup of contaminated groundwaterassociated with Resource Conservation and RecoveryAct (RCRA) hazardous waste management facilitiesor Federal Facility Act units. ERD’s mission is toaggressively manage the inactive waste site andgroundwater cleanup program so that

� schedules for environmental agreements areconsistently met

� the utilization of financial and technologyresources are continually improved

� the overall risk posed by existing contaminatedsites is continually reduced

The strategy of ERD, which has developed amanagement action plan for groundwater, revolvesaround developing an appropriate regulatoryframework for each waste site, assessing the degreeand extent of contamination, and remediating thecontaminated groundwater to its original beneficialuse. In cases where that remediation goal isimpractical, ERD intends to prevent plume migrationand exposure and to evaluate alternate methods ofrisk reduction.

Reporting Results of GroundwaterProgram Activities

In addition to its annual environmental report, SRSpublishes several reports related to the sitegroundwater program. Some of these are referencedin this chapter, including (1) compliance andinvestigation reports developed for groundwaterremediation activities, (2) a sampling scheduledescribing annual monitoring activities (3) varioussite-specific groundwater monitoring reports forregulatory compliance (4) quarterly groundwatermonitoring reports, and (5) the biannual wellinventory. Beginning in 2002, an annual report of thesite Groundwater Surveillance Monitoring Programalso will be issued.

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Description of the GroundwaterMonitoring Program

The groundwater monitoring program at SRS gathersinformation to determine the effect of site operationson groundwater quality. The program is designed to

� assist SRS in complying with environmentalregulations and DOE directives

� provide data to identify and monitor constituentsin the groundwater

� permit characterization of new facility locationsto ensure that they are suitable for the intendedfacilities

� support basic and applied research projects

The groundwater monitoring program at SRS isconducted by the Environmental GeochemistryGroup (EGG) of EPD’s Environmental MonitoringSection (EMS). To assist other departments inmeeting their responsibilities, EGG provides theservices for installing monitoring wells, collectingand analyzing samples, and reporting results.

The WSRC Environmental Compliance Manual(WSRC–3Q1) provides details about the followingaspects of the groundwater monitoring program:

� well siting, construction, maintenance, andabandonment

� sample planning

� sample collection and field measurements

� analysis

� data management

� related publications, files, and databases

The remainder of this chapter presents overviews ofseveral of these topics, along with informationspecific to 2001.

Sample Scheduling and Collection

EMS schedules groundwater sampling either inresponse to specific requests from SRS personnel oras part of its ongoing groundwater monitoringprogram. These groundwater samples provide datafor reports required by federal and state regulationsand for internal reports and research projects. Thegroundwater monitoring program schedules wells tobe sampled at intervals ranging from quarterly totriennially.

Personnel outside EMS may request samplecollection as often as weekly. Constituents that maybe analyzed are commonly imposed by permit or

work plan approval. Those include metals, fieldparameters, suites of herbicides, pesticides, volatileorganics, and others. Radioactive constituents thatmay be analyzed by request include gross alpha andbeta measurements, gamma emitters, iodine-129,strontium-90, radium isotopes, uranium isotopes, andother alpha and beta emitters.

Groundwater samples are collected from monitoringwells, generally with either pumps or bailersdedicated to the well to prevent cross–contaminationamong wells. Occasionally, portable samplingequipment is used; this equipment is decontaminatedbetween wells.

Sampling and shipping equipment and procedures areconsistent with EPA, SCDHEC, and U.S. Departmentof Transportation guidelines. EPA–recommendedpreservatives and sample–handling techniques areused during sample storage and transportation to bothonsite and offsite analytical laboratories. Potentiallyradioactive samples are screened for total activity(alpha and beta emitters) prior to shipment todetermine appropriate packaging and labelingrequirements.

Deviations (caused by dry wells, inoperative pumps,etc.) from scheduled sampling and analysis for 2001are enumerated in the SRS quarterly groundwatermonitoring reports cited previously in this chapter.

Analytical Procedures

In 2001, General Engineering Laboratories ofCharleston, South Carolina; Recra LabNetPhiladelphia of Lionville, Pennsylvania; and SanfordCohen and Associates of Montgomery, Alabama,performed most of the groundwater analyses. Inaddition, the General Engineering Mobile Laboratoryperformed onsite analyses of volatile organics andsemivolatile organics and metals. EMAXLaboratories, Inc., of Torrance, California, performedanalyses for several sampling projects, andMicroSeeps of Pittsburgh, Pennsylvania, performednatural attenuation analyses. The contractedlaboratories are certified by SCDHEC to performspecified analyses.

The EMS laboratory at SRS screened potentiallyradioactive samples for total activity prior toshipment. General Engineering Laboratoriesperformed radiological analyses, and Thermo NUtechof Oak Ridge, Tennessee, subcontracted radiologicalanalyses from Recra LabNet Philadelphia.

Full lists of constituents analyzed, analytical methodsused, and the laboratories’ estimated quantitationlimits are given in the SRS quarterly groundwaterreports referenced earlier.

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Evaluation of Groundwater Data

EMS receives analytical results and fieldmeasurements as reports and as ASCII files that areloaded into databases at SRS. For 2001, logbookstrack receipt and transfer of data to the GeochemicalInformation Management System (GIMS) database orto the Environmental Restoration Data ManagementSystem (ERDMS), and computer programs presentthe data in a format that can be validated.

Quality control practices include the following:

� verification of well names and sample dates forfield and analytical data

� verification that all analyses requested on thechain-of-custody forms were completed by eachlaboratory

� identification of data entry problems (e.g.,duplicate records, incorrect units)

� comparison of analytical data to historical dataand review of the data for transcription,instrument, or calculation errors

� comparison of blind replicates and laboratoryin-house duplicates for inconsistencies

� identification of laboratory blanks and blindblanks with elevated concentrations

Possible transcription errors and suspect results aredocumented and submitted to the appropriatelaboratory for verification or correction. No changesare made to the database until the laboratorydocuments the problem and solution. Changes to thedatabase are recorded in a logbook.

The quarterly groundwater monitoring reportsidentify queried results verified by the laboratory andlist groundwater samples associated with blankshaving elevated results. These reports also present theresults of intralaboratory and interlaboratory qualityassurance comparisons (chapter 9, “QualityAssurance”).

Changes to the GroundwaterMonitoring Program during 2001

Well Abandonments and Additions;Changes to the Sampling Schedule

During 2001, two wells were abandoned—one inA-Area/M-Area and another in the A-Areaburning/rubble pits.

The following 212 wells were scheduled to bemonitored for the first time in 2001:

� Fifty-one new wells in the chemicals, metals, andpesticides pits in order to determine the natureand extent of contamination

� Two wells in the Jackson Wells project as wellsadded to the GSMP.

� Thirteen wells in the miscellaneous chemicalbasins for an Inductively CoupledPlasma/Remedial Action Implementation Plan

� Fifteen wells in the southern sector for theGroundwater Effectiveness Monitoring Strategyfor the proposed Southern Sector Phase 1Groundwater Corrective Action

� Twenty wells in the A-Area burning/rubble pitsfor Interim Corrective MeasuresImplementation/Remedial ActionImplementation Plan

� Twenty-four wells in the D-Area expandedoperable unit for the RCRA FacilityInvestigation/Remedial Investigation WorkplanAddendum

� Twelve wells in the F-Area Seepage BasinsInjection Study to provide information to beutilized in the evaluation of the Base InjectionStudy

� Seventeen wells for the A-Area/M-AreaCretaceous Wells project for A-Area/M-Areagroundwater

� Nine wells at the R-Reactor seepage basins toprovide additional field data to support thedevelopment of the Corrective MeasuresStudy/Feasibility Study

� Six wells at the H-Area groundwater treatmentunit to establish decontamination factors tofacilitate remedial decision making

� Thirteen wells at the Mixed Waste ManagementFacility for RCRA compliance sampling

� Fourteen wells in the General Site for the GSMP

� Thirteen wells in the sanitary landfill forcompliance with South Carolina HazardousWaste Management Regulations, Solvent RagSettlement (91–51–SW), GWQAP 1995; andcomprehensive monitoring evaluation auditESH–CGP–2000–00136

� Three wells in A-Area/M-Area for productionwell sampling at SCDHEC request

Groundwater MonitoringResults at SRSThis section summarizes groundwater monitoringresults during 2001 for each of the following areas atSRS:

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� A-Area and M-Area

� C-Area

� D-Area and TNX-Area

� General separations and waste management areas(E-Area, F-Area, H-Area, S-Area, and Z-Area)

� K-Area

� L-Area and chemicals, metals, and pesticides pits

� N-Area

� P-Area

� R-Area

� Sanitary landfill

Additional information about groundwatercontamination, monitoring, and cleanup in most ofthese areas can be found at the following internetaddress: http://www.srs.gov/general/pubs/fulltext/fulltext–2001.htm.

Groundwater Contamination atA-Area and M-Area

The administration and manufacturing areas (A-Areaand M-Area) are located in the northwestern part ofSRS and include a number of facilities associatedwith the site’s groundwater cleanup and monitoringprograms (figure 8–1). The area contains facilitiesthat were used for the manufacture of reactor fuel andtarget assemblies, support services, laboratories, andadministration. The manufacturing facilities wereoperational from the 1950s into the early 1980s.Major contaminants include volatile constituents,particularly trichloroethylene and tetrachloroethylene,used as degreasers in old manufacturing processes.Wastewater from the manufacturing operationsflowed into the M-Area Settling Basin and the LostLake, a shallow body of water that received runofffrom the settling basin; these two units make up thehazardous waste management facilities (HWMF).Additional details about the A-Area and M-Areagroundwater cleanup and monitoring programs canbe found in the SRS RCRA permit application andFFA documents.

Cleanup activities, focusing on both groundwater andthe overlying soil column, have substantially alteredthe groundwater flow and spread of contamination.These efforts have included the capping of basins andthe extraction of contaminants from groundwater. Tocontain the trichloroethylene and tetrachloroethyleneplumes in groundwater, SRS installed groundwaterrecovery systems in A-Area and M-Area. Thesesystems include pumping wells installed in the SteedPond aquifer and air stripper units for treating the

water. The clean water is discharged through apermitted outfall to an SRS stream. Groundwatermonitoring and numerical modeling tasks havedemonstrated the effectiveness of the groundwaterrecovery systems in controlling migration of thetrichloroethylene and tetrachloroethylene plumesassociated with the HWMF. Since the system beganoperating in 1984, almost a million pounds ofsolvents have been recovered via the groundwaterrecovery systems in A-Area and M-Area. Thecorrective action plan, approved by SCDHEC in1987, requires groundwater cleanup operation andmonitoring in A-Area and M-Area for 30 years.

Other technologies are in use at A-Area and M-Areato recover chlorinated solvent plumes and perform insitu remediation. These plumes are associated withindividual operable units or facilities, but also maycommingle or be in hydraulic communication withthe larger trichloroethylene and tetrachloroethyleneplume in the Steed Pond aquifer beneath A-Area andM-Area. Twenty-three vertical recirculation wells arein use at the miscellaneous chemical basin and in thesouthern sector of A-Area and M-Area. Also,phytoremediation is in use at the southern sector torecover the distal (low concentration) area of thegroundwater plume. Air sparging wells and shallowsoil vapor extraction units are operating at the A-Areaburning/rubble pits. Soil vapor extraction is in use atthe A–014 outfall, M-Area settling basin, andmiscellaneous chemical basin.

In September 2000, SRS began operation of atechnology known as dynamic underground stripping(DUS). DUS was deployed at the M-Area solventstorage tank area, which was known to have a densenonaqueous phase liquid source that released volatileorganic compounds (VOCs) to the A-Area andM-Area groundwater plume. The DUS technologyvaporizes VOCs in the permeable zones of thetreatment area by injecting steam into the subsurfacesoil and heating the VOC contaminants above theirboiling points. Contaminants are removed by physicaltransport to extraction wells and by in situ destructionof contaminants with a thermally acceleratedoxidation process. When DUS operations werediscontinued in September 2001, more than 70,000pounds of VOCs had been removed from thetreatment area.

Groundwater Contaminationat C-AreaSeveral groundwater contaminant plumes have beencharacterized by data collected from numerousmonitoring wells and cone penetrometer locations inthe C-Area groundwater operable unit (figure 8–1).Significant plumes of tritium and trichloroethylene

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have been identified in the area. Two distinct tritiumplumes have been identified—a northern tritiumplume and a southern tritium plume. These plumesare derived from several separate sources, some ofthem undetermined at this time. In addition, twodistinct plumes of trichloroethylene have beenidentified: a northern trichloroethylene plume, and asouthern trichloroethylene plume. The sourcelocation of the northern trichloroethylene plume hasbeen identified at the C-Area burning/rubble pit, andthe source of the southern trichloroethylene plume isan undefined area inside of the C-Area reactor fence.

The two tritium plumes and the southerntrichloroethylene plume, which emanates from theC-Area reactor, are administratively associated withthe C-Area groundwater operable unit. Thetrichloroethylene plume from the C-Areaburning/rubble pit is administratively associated withthe C-Area burning/rubble pit operable unit.

As indicated by the field-derived plumeconfiguration, groundwater originating from justbeneath the C-Reactor building (105–C) appears to beflowing south, southwest with eventual discharge toCastor Creek and Fourmile Branch. Groundwatermigrating from potential source locations of theC-Area burning/rubble pit trichloroethylene andtritium plumes appears to be flowing to the west, witheventual discharge to Fourmile Branch.

Groundwater Contaminationat D-Area and TNX-Area

D-Area, located in the southwest part of SRS,includes a large coal-fired power plant anddecommissioned heavy water facilities. TNX-Area,also located in the southwest part of the site, was usedto test equipment and develop new designs. Severalunits are associated with groundwater monitoring andcleanup in these two areas (figure 8–1).

Contamination at D-Area and TNX-Area occurs inthe Upper Three Runs aquifer, a shallow water table(figure 8–3). Volatile organic constituents,particularly trichloroethylene, are the primarycontaminants. In D-Area, there is substantialcontamination of the groundwater near the coal pile,coal pile runoff containment basin, and ash basins.This contamination is consistent with low-pHconditions, the leaching of coal and coal ash, and thedischarge of chlorinated degreasing solvents. Themost widespread contaminant at D-Area istrichloroethylene; other contaminants include heavymetals and tritium. A phytoremediation system isbeing tested for the treatment of groundwatercontaminated by trichloroethylene. A separate plume

of volatile organics (especially trichloroethylene) andlead has been associated with disposal activities at theD-Area oil seepage basin. A groundwater mixingzone application was approved by SCDHEC in 1998for chlorinated solvents.

There is a shallow plume of contaminatedgroundwater beneath much of TNX-Area anddowngradient into the Savannah River Swamp.Contaminants in the groundwater includeradionuclides, heavy metals, and VOCs—especiallytrichloroethylene. The highest concentrations oftrichloroethylene are found northwest and southeastof the TNX burying ground. A separate plumeappears to be moving to the southwest of the TNXoutfall delta toward the X–08 ditch. Groundwatercleanup at TNX-Area utilizes a groundwater recoverysystem and a soil vapor extraction system. Geosiphonwells have been installed in the lower swamp area forrecovering trichloroethylene that is moving towardthe Savannah River.

Groundwater Contaminationat the General Separationsand Waste Management Areas

The separations and waste management areas, whichinclude E-Area, F-Area, H-Area, S-Area, and Z-Area,are located in the center of SRS. Reactor-producedmaterials are processed in the chemical separationsplants, or “canyons,” at F-Area and H-Area. Theseparations and waste management areas, also calledthe General Separations Area (GSA), contain manyunits associated with the groundwater monitoring andcleanup programs (figure 8–1).

Both surface and groundwater divides run from eastto west between Upper Three Runs Creek andFourmile Branch. In the Upper Three Runs aquifer(figure 8–3), groundwater in the northern GSA flowsnorth into Upper Three Runs Creek, whilegroundwater in in the southern GSA flows intoFourmile Branch. The flow dynamics change in theGordon aquifer, where flow is to the northwest overmost of the GSA.

The most extensive groundwater monitoring andcleanup programs in these areas are associated withthree RCRA-regulated facilities—the F-Area HWMF,the H-Area HWMF, and the Burial Ground Complex.Tritium is the most common contamination at allthree facilities, but metals, other radionuclides, andvolatile organic constituents also are present. Acomplex groundwater cleanup system has beenoperating at the F-Area and H-Area HWMFs forseveral years, but work at the Burial GroundComplex now is directed toward plumecharacterization. Much of the cleanup emphasis is on

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constraining the flow of contaminant plumes intoFourmile Branch.

Groundwater Contaminationat K-Area

There are four known plumes of groundwatercontamination in K-Area (figure 8–1). Primarycontaminants include trichloroethylene,tetrachloroethylene and tritium. A small, isolatedplume of trichloroethylene and tetrachloroethylene isassociated with the K-Area burning/rubble pit andrubble pile, on the northeast side of the K-Areareactor. There is no continuing source, and the plumeis not discharging to surface water. A groundwatermixing zone application has been approved for thisoperable unit.

A tritium plume, termed “tritium anomaly plume,” islocated northwest of the reactor (figure 8–1). Thisplume has not been fully characterized, but extends atleast 2,000 feet from somewhere inside the reactorfence to a surface discharge point in Indian GraveBranch. It has been named the tritium anomaly plumebecause especially high tritium values have beenmeasured in monitoring wells and surface water. Thisplume is slated to be investigated under the K-Areagroundwater operable unit. In addition, the K-AreaGroundwater Operable Unit will include anothertritium plume emanating from the vicinity of theretention basin and discharging into surface water anda trichloroethylene plume intermingled with thetritium anomaly plume. These plumes will beinvestigated under the site RCRA/ComprehensiveEnvironmental Response, Compensation, andLiability Act program.

Groundwater Contaminationat L-Area and the Chemicals,Metals, and Pesticides Pits

L-Area groundwater contamination is associated withseveral units, including the chemicals, metals, andpesticides pits, the L-Area burning/rubble pit, andseveral units located next to and in the L-Area reactorarea (figure 8–1).

Contaminants above the maximum contaminant limitfrom the chemicals, metals, and pesticides pitsinclude tetrachloroethylene, trichloroethylene, anddaughter products; lindane; carbon tetrachloride; andchloroform. Groundwater flows north, northwestfrom the pits toward Pen Branch. Groundwatermodeling in this area is under way.

At the L-Area burning/rubble pit, carbon tetrachlorideis the only groundwater constituent of concern.

Groundwater in this area flows west toward PenBranch, downstream of the chemicals, metals, andpesticides pits. Groundwater flow and transportmodeling in this area has been completed.Contamination will not discharge to surface waterbased on modeling predictions. There is also anapproved groundwater mixing zone.

Contamination in the reactor area includestrichloroethylene, tetrachloroethylene and tritium.Groundwater in this area flows south toward L Lake.Groundwater modeling will begin for these plumes infiscal year 2002.

Groundwater Contaminationat N-Area

N-Area, also called the Central Shops area, is locatedin the central part of SRS and provides supply,maintenance, and other support services for the site(figure 8–1). Groundwater contamination in N-Areais associated with organic compounds, includingchlorinated solvents (trichloroethylene), as well asheavy metals.

Chlorinated solvents have been used throughoutN-Area. It is believed that most of the solvents endedup in floor drains that emptied into a drainage ditchnear the center of the area. Groundwatercontamination in N-Area has been detected only atthe SRL oil test site and at the heavy-equipment washbasin and Central Shops burning/rubble pit (631–5G).An effort is under way to administratively create anew groundwater operable unit in N-Area because itis believed that the source of the groundwatercontamination is the drainage ditch, not the surfaceunits.

At the SRL oil test site, groundwater contamination(tetrachloroethylene, trichloroethylene, and carbontetrachloride) has been detected in both shallow anddeep zones of the Upper Three Runs aquifer (figure8–2). The SRL oil test site was developed(1975–1977) to evaluate the natural biodegradation ofpetroleum waste or waste oil.

The heavy-equipment wash basin and Central Shopsburning/rubble pit was used to clean and maintainequipment until 1981. The highest concentrations oftrichloroethylene (6,500 parts per billion) exist in theshallow Upper Three Runs aquifer near the outfall. Inthis area, a competent clay layer just beneath thesurface supports a perched-water zone, which flowstoward the drainage ditch. The trichloroethyleneplume exists in two “lobes.” One movesdowngradient on top of a clay layer in the UpperThree Runs aquifer; the other has been drawn deeperinto the lower part of the Upper Three Runs aquifer

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toward a shallow groundwater production well (nowabandoned).

Groundwater Contaminationat P-Area

Groundwater in P-Area is discharging in the SteelCreek watershed (figure 8–1). The area is still in theearly stages of characterization, and groundwatermodeling has not yet begun. Current data suggest thattritium and trichloroethylene plumes exist above themaximum contaminant limit. No site-specificgroundwater modeling documents are available yetfor this area.

Groundwater Contaminationat R-Area

Groundwater contamination exists at concentrationsabove maximum contaminant limits in R-Area (figure8–1). Contamination includes tritium, strontium-90,tetrachloroethylene, and trichloroethylene. Threeoperable units in R-Area are geographicallyassociated with groundwater contamination—theR-Area reactor seepage basins, the R-Area Binghampump outage pits, and the R-Area burning/rubble pits.

The tritium plume is widespread, exceeds themaximum contaminant limit, and is poorly defined.This contaminant will be characterized under theR-Area groundwater operable unit. Strontium-90contamination has been discovered adjacent to theR-Area Reactor seepage basins in the very shallowgroundwater. Vadose zone modeling and flow andtransport modeling are in progress for this plume,which is not discharging to surface water. Finalreports are expected June 2002. Thetetrachloroethylene and trichloroethylene plumes areassociated with the R-Area Bingham pump outage pitand with the R-Area burning/rubble pits and rubblepile. These plumes will be addressed under theR-Area groundwater operable unit. The nearestpossible discharge area for the R-Area Binghampump outage pits plume is Joyce Branch, upstreamfrom PAR Pond. The likely discharge point for theplume near the R-Area burning/rubble pits and rubblepile is Pond 4 of PAR Pond.

Groundwater Contamination at theSanitary Landfill

The sanitary landfill is located in B-Area, south ofRoad C, about halfway down the slope of the Aiken

Plateau to Upper Three Runs Creek (figure 8–1). Thelandfill received general SRS wastes fordisposal—such as paper, cafeteria wastes, plastics,wood, cardboard, rags, scrap metal, pesticide bags,asbestos (in bags), and sludge from SRS wastewatertreatment facilities—beginning in 1974. The “trenchand fill” method of waste disposal was used, and thewastes were covered by natural soil or a fabricsubstitute. The natural water table is in or near thebottom of the waste trenches. The sanitary landfillceased operations in 1994.

Sanitary landfills are intended to receive onlynonradioactive, nonhazardous waste. However, untilOctober 1992, some hazardous wastes (specifically,solvent-laden rags and wipes used for cleaning,decontamination, and instrument calibration) wereburied in portions of SRS’s original 32-acre landfilland its southern expansion. Groundwatercontamination consists of low concentrations ofVOCs, but tritium, metals, and other radionuclidesalso are present.

Several remediation activities have been successful inaddressing groundwater contamination at the sanitarylandfill. A RCRA-style cap was installed over themain and southern expansion sections in 1996–1997.The cap has been effective in eliminating (1) therecharge effects of precipitation through the landfilltrenches and (2) the mobility of contaminants in thewastes.

A biosparging system consisting of two horizontalwells began operation in 1999. These wells areinstalled south and southwest of the landfill andintercept the vinyl chloride plume that extendsbeyond the point-of-compliance wells south of thelandfill. This remediation system involves theinjection of air and nutrients resulting in thevolatilization and degradation of trichloroethyleneand vinyl chloride.

Groundwater monitoring results have shown that thelandfill cap has reduced the migration ofcontaminants into the groundwater under the sanitarylandfill and has facilitated the reductivedechlorination of chlorinated solvents. Also, thebiosparging system has proven effective ingroundwater cleanup.