6. y-12 environmental monitoring programs · y-12 environmental monitoring programs 6-1 6. ......

Y-12 Environmental Monitoring Programs 6-1

6. Y-12 Environmental Monitoring Programs

Compliance and environmental monitoring programs required by federal and state regulation and byDOE orders are conducted at the Y-12 National Security Complex for air, water, and groundwater environ-mental media.

6.1 Y-12 COMPLEX RADIO-LOGICAL AIRBORNEEFFLUENT MONITORING

The release of radiological contaminants,primarily uranium, into the atmosphere at theY-12 National Security Complex (Y-12 Complex)occurs almost exclusively as a result of plantproduction, maintenance, and waste managementactivities. National Emission Standards forHazardous Air Pollutants (NESHAP) regulationsfor radionuclides require continuous emissionsampling of major sources (a “major source” isconsidered to be any emission point that poten-tially can contribute more than 0.1 mrem/yeareffective dose equivalent to an off-site individual).During 2001, 43 of the 55 monitored stacks werejudged to be major sources. Eighteen of the stackswith the greatest potential to emit significantamounts of uranium are equipped with alarmedbreakthrough detectors, which alert operationspersonnel to process-upset conditions or to adecline in filtration-system efficiencies, allowingthem to investigate and correct the problem beforea significant release occurs. As of January 1,2001, the Y-12 Complex had continuousmonitoring capability on a total of 57 stacks, 48 ofwhich were active and 9 of which were tem-porarily shut down. Two of these stacks that weretemporarily shut down, US-002 and UB-111, werepermanently shut down in 2001.

Emissions from unmonitored process andlaboratory exhausts, categorized as minoremission sources, are estimated according tocalculation methods approved by the U.S. Envi-ronmental Protection Agency (EPA). In 2001,there were 41 unmonitored processes operated byY-12. These are included as minor sources in theY-12 Complex source term.

Uranium and other radionuclides are handledin millicurie quantities at facilities within the

boundary of the Y-12 Complex as part of BechtelJacobs Company LLC (BJC), ORNL, and BWXTY-12 laboratory activities. Twenty-eight minoremission points were identified from laboratoryactivities at facilities within the boundary of theY-12 Complex as being operated by BWXT Y-12.In addition, the BWXT Y-12 Analytical Chemis-try Organization laboratory is operated in a leasedfacility that is not within the ORR boundary andis located approximately 1/3 mile east of the Y-12Complex on Union Valley Road. The emissionsfrom the Analytical Chemistry OrganizationUnion Valley laboratory are included in the Y-12Complex source term. Eight minor emissionpoints were identified at the laboratory. Thereleases from these emission points are minimal,however, and have negligible impact on the totalY-12 Complex dose.

Emissions from Y-12 Complex room ventila-tion systems are estimated from radiation controldata collected on airborne radioactivity concentra-tions in the work areas. Areas where the monthlyaverage concentration exceeded 10% of the DOEderived air concentration worker-protection guide-lines are included in the annual emission estimate.One emission point in Building 9212 wasidentified in 2001 where room ventilation emis-sions exceeded 10% of the guidelines. However,because this enclosure exhausted to stack UB-110,its contribution was not specifically identified andwas included in the stack emissions.

6.1.1 Sample Collection andAnalytical Procedure

Uranium stack losses were measured con-tinuously on monitored operating process exhauststacks in 2001. Particulate matter (includinguranium) was filtered from the stack emissions.Filters at each location were changed routinely,from one to three times per week, and were

Oak Ridge Reservation

6-2 Y-12 Environmental Monitoring Programs

Fig. 6.1. Total curies of uranium dischargedfrom the Y-12 Complex to the atmosphere,1996–2001.

Fig. 6.2. Total kilograms of uranium dischargedfrom the Y-12 Complex to the atmosphere,1996–2001.

analyzed for total uranium. In addition, thesampling probes and tubing were removedquarterly and were washed with nitric acid; thewashing was analyzed for total uranium. At theend of the year, the probe-wash data wereincluded in the final calculations in determiningtotal emissions from each stack.

6.1.2 Results

An estimated 1.44E × 10–2 Ci (3.4 kg) ofuranium was released into the atmosphere in 2001as a result of Y-12 activities. The specific activityof enriched uranium is much greater than that ofdepleted uranium, and about 87% of the curierelease was composed of emissions of enricheduranium particulate, even though approximately6% of the total mass of uranium released wasenriched material (Figs. 6.1 and 6.2).

6.2 Y-12 COMPLEXNONRADIOLOGICALAIRBORNE EMISSIONSMONITORING

The release of nonradiological contaminantsinto the atmosphere at the Y-12 Complex occursas a result of plant production, maintenance, wastemanagement operations, and steam generation.Most process operations are served by ventilationsystems.

In CY 2001, the Y-12 Complex had 36 indi-vidual air permits. Approximately two-thirds ofthe permitted air sources release primarily non-radiological contaminants. The remaining one-third of the permitted sources process primarilyradiological materials. Tennessee Department ofEnvironment and Conservation (TDEC) airpermits for the nonradiological sources do notrequire stack sampling or monitoring except forthe opacity monitors used at the steam plant toensure compliance with visible emissionstandards. For nonradiological sources wheredirect monitoring of airborne emissions is notrequired, monitoring of key process parameters isdone to ensure compliance with all permittedemission limits. In the future, when the Y-12Complex is issued its first-ever major source(Clean Air Act Title V) operating permit,reporting of key process parameters is expected toincrease. Also, it is anticipated that a future permitcondition for the steam plant will requirecontinuous emission monitoring for nitrogenoxides beginning in 2003.

The 2001 Y-12 Complex annual emission feewas calculated based on 10,033 tons per year ofallowable emission of regulated pollutants, withan annual emission fee of $130,429. In accordancewith TDEC regulations, Rule 1200-3-26-.02(9)(i),when there is no applicable standard or permitcondition for a pollutant, the allowable emissionsare based on the maximum actual emissions calcu-lations (maximum design capacity for8760 h/year). More than 90% of the Y-12 Com-

Annual Site Environmental Report


Table 6.1. Actual vs allowable air emissions from the Oak RidgeY-12 Complex, 2001

Pollutant

Emissions(tons/year) Percentage of

allowableActual Allowable

Particulate 20 931 2.2

Sulfur dioxide 1,954 20,803 9.4

Nitrogen oxidesa 900 7,718 11.7

Volatile organic compoundsa 2.4 37 6.5

Carbon monoxidea 33 543 6.1

aWhen there is no applicable standard or enforceable permit condition forsome pollutants, the allowable emissions are based on the maximum actualemissions calculation as defined in Tennessee Department of Environmentand Conservation Rule 1200-3-26-.02(2)(d)3 (maximum design capacity for8,760 h/year). The emissions for both the actual and allowable emissionswere calculated based on the latest EPA compilation of air pollutantemission factors. (EPA 1995. Compilation of Air Pollutant EmissionFactors AP-42, Fifth Edition, Volume 1: Stationary Point and Area Sources.U.S. Environmental Protection Agency, Research Triangle Park, N.C.January 1995.)

plex pollutant emissions to the atmosphere areattributed to the operation of the steam plant. Theemission fee rate was based on $13 per tonof regulated-pollutant allowable emissions. Theactual emissions are much lower than the allow-able amount; however, major sources are requiredto pay their annual emission fees based onallowable emissions until the issuance of themajor source operating permit.

6.2.1 Results

The primary source of criteria pollutants atthe Y-12 Complex is the steam plant, where coaland natural gas are burned. Information regardingactual vs allowable emissions from the steamplant is provided in Table 6.1. In addition, theannual toxic release inventory report (required bythe Emergency Planning and Community Right-to-Know Act, Sect. 313) provides information onother nonradiological Y-12 Complex air emissions(Sect. 2.2.16).

The east and west Y-12 Steam Plant stackopacity monitors were each operational more than99% of the time in 2001. Both systems were takenout of service for annual calibration/certificationon April 17 and 18, 2001. The annual opacity cali-

bration error test reports were submitted to TDECin July 2001. During 2001, there were two 6-minperiods of excess emissions and two occasionswhen the monitors were out of service. Quarterlyreports of the status of the Y-12 Steam Plantopacity monitors are submitted to personnel atTDEC within 30 days after the end of eachcalendar quarter. Table E.4 in Appendix E is arecord of excess emissions and out-of-serviceconditions for the east and west stack opacitymonitors for 2001.

6.3 Y-12 COMPLEX AMBIENTAIR MONITORING

In 1994, Y-12 Complex personnel issuedEvaluation of the Ambient Air MonitoringProgram at the Oak Ridge Y-12 Plant (MMES1994b) and worked with DOE and TDEC inreviewing the ambient air program forapplicability and usefulness of the data. There areno federal regulations, state regulations, or DOEorders that require this monitoring. All ambient airmonitoring systems at the Y-12 Complex areoperated as a best management practice. With thereduction of plant operations and improvedemission and administrative controls, levels of



Fig. 6.3. Locations of ambient air monitoring stations at the Y-12 Complex.

measured pollutants have decreased significantlyduring the past several years. In addition, majorprocesses that result in emission of enriched anddepleted uranium are equipped with stacksamplers that have been reviewed and approvedby EPA to meet requirements of the NESHAPregulations. ORR air sampling stations, operatedby ORNL in accordance with DOE orders, arelocated around the reservation. Their locationswere selected so that areas of potentially highexposure to the public are monitored continuouslyfor parameters of concern.

With agreement from TDEC personnel, theambient air-sampling program at the Y-12 Com-plex was significantly reduced, effective at theend of 1994. All sampling for fluoride, totalsuspended particulates, and particulate matter lessthan 10 microns in diameter (PM10) wasdiscontinued, and all but 3 of the 12 uraniumsamplers were shut down. Effective April 1, 1999,an agreement was reached according to whichTDEC personnel took over responsibility forsampling and analysis of the three remaininguranium samplers at the Y-12 Complex. Theuranium samplers were operated by the TDECduring 2001. On December 6, 1999, DOEsubmitted to TDEC a letter providing justificationfor reducing the number of on-site mercury-monitoring stations from four to two. EffectiveJanuary 1, 2000, operation of the two monitorslocated in the interior of the Complex (nearBuildings 9805-1 and 9422-13) was discontinued.

The two boundary mercury-monitoring stations(stations 2 and 8) remain in operation. The loca-tions of these monitoring stations are shown inFig. 6.3. During 2001, modeling was performed todetermine whether monitoring for fluorides wouldbe prudent commensurate with the restart of thehydrogen fluoride system at Building 9212. Thesedata are still being analyzed.

6.3.1 Mercury

The Y-12 Complex ambient air monitoringprogram for mercury was established in 1986 as abest management practice. The objectives of theprogram are to establish a historical database ofmercury concentration in ambient air at the Y-12Complex, identify spatial and temporal trends inmercury vapor concentrations at Y-12, anddemonstrate protection of the environment andhuman health from releases of mercury from Y-12to the atmosphere. Beginning in CY 2000, thenumber of program monitoring stations wasreduced from four to two (see discussion inSect. 6.3). The two stations, Ambient Air StationNo. 2 and Ambient Air Station No. 8, are locatednear the east and west boundaries of the Y-12Complex, respectively (see Fig. 6.3). Since theirestablishment in 1986, stations 2 and 8 havemonitored mercury in ambient air continuouslywith the exception of short periods of downtimedue to power or equipment outages. In addition to



Table 6.2. CY 2001 summary results for the Y-12 Complex mercury in ambient air monitoring programResults for the 1986 through 1988 monitoring period are shown for reference

Ambient air monitoring stations

Mercury vapor concentration (µg/m3)

2001Average

2001Maximum

2001Minimum

1986–1988Average

Station No. 2 (east end of Y-12) 0.0034 0.0136 0.0008 0.010

Station No. 8 (west end of Y-12) 0.0042 0.0100 0.0010 0.033

Reference Site, Rain Gauge No. 2 (1988a) N/A N/A N/A 0.006

Reference Site, Rain Gauge No. 2 (1989b) N/A N/A N/A 0.005

aData for period from February 9 through December 31, 1988. bData for period from January 1 through October 31, 1989.

the Y-12 Complex monitoring stations, a controlor reference site was operated on Chestnut Ridgein the Walker Branch Watershed (Rain GaugeNo. 2) for a 20-month period in 1988 and 1989 toestablish background concentrations.

At each of the monitoring sites, airbornemercury vapor is collected by pulling ambient airthrough a sampling train consisting of a Teflonfilter, a flow-limiting orifice, and an iodated char-coal glass sampling tube or trap. The flow-limiting orifice restricts air flow through thesampling train to ~1L/min, although actual flowrates are measured weekly with a calibratedflowmeter. The iodated charcoal sampling tubesare changed out routinely, every 7 days. Thecharcoal in each trap is then analyzed for totalmercury by using cold vapor atomic fluorescenceafter acid digestion. Average concentration ofmercury vapor in air for each 7-day samplingperiod is calculated by dividing the total quantityof mercury collected on the charcoal by the totalvolume of air pulled through the charcoal trapduring the sampling period. During the first fewyears of the program, the Teflon filters in thesampling train were analyzed for particulatemercury, but this practice was discontinued in1989 after results revealed very low toundetectable levels of particulate mercury.

As reported in previous annual site environ-mental reports, over the 16 years of the moni-toring program, average annual mercury vaporconcentrations at the Y-12 Complex mercurymonitoring sites have declined, especially sincethe initial 3 years of the monitoring program(1986 through 1988). Average mercury vaporconcentrations at Ambient Air Station 8 have

declined almost tenfold and threefold at Station 2since the 1986–1988 period. Recent averageannual concentrations at the two boundarystations located at the east and west ends of theY-12 Complex are comparable to those measuredin 1988 and 1989 at the Chestnut Ridge referencesite and are only slightly elevated above concen-trations reported for continental background (i.e.,~0.002 µg/m3). Annual average mercury concen-tration during 2001 at Station 2 was 0.0034 µg/m3

(N = 51; standard error = ±0.0003) and atStation 8, 0.0042 µg/m3 (N = 51; standard error =±0.0003). Table 6.2 summarizes the CY 2001mercury results and provides the results from the1986– 1988 period for comparison. Figure 6.4illustrates temporal trends in mercury concen-trations for the two active ambient air mercury-monitoring sites since the inception of theprogram in 1986 through December 2001.

In conclusion, annual average ambientmercury concentrations during 2001 at the Y-12east and west boundary monitoring sites are com-parable to reference levels measured on ChestnutRidge in 1988 and 1989 and approach the averagevalues reported for continental background. Theseconcentrations are well below the AmericanConference of Governmental Industrial Hygienistsworkplace threshold limit value of 25 µg/m3

(time-weighted average for a normal 8-h workdayand 40-h work week) and the EPA referenceconcentration of 0.3 µg/m3 for mercury forchronic inhalation exposure.



Fig. 6.4. Temporal trends in mercury vapor concentration for the four active airborne mercury monitoringsites at the Oak Ridge Y-12 Complex, July 1986 through July 2001. The dashed line represents the EPAreference concentration of 0.3 µg/m3.

6.4 LIQUID DISCHARGES—Y-12 COMPLEX RADIO-LOGICAL MONITORINGSUMMARY

A radiological monitoring plan is in place atthe Y-12 Complex to address compliance withDOE orders and the National Pollutant DischargeElimination System (NPDES) permit(TN002968). The permit, issued in 1995, requiredY-12 to reevaluate its radiological monitoringplan and to submit results from the monitoringprogram quarterly as an addendum to the NPDESDischarge Monitoring Report. There were no dis-charge limits set by the NPDES permit for radio-nuclides; the requirement is to monitor and report.A revised plan (LMES and H&R 1995) was fullyimplemented in 1995. The radiological monitoringplan was expanded at that time to allow sufficientcollection of data such that an assessment ofalpha, beta, and gamma emitters could be made.

The intent was to more appropriately identifyparameters to be monitored and to establishanalytical detection limits necessary for doseevaluations.

Based on an analysis of operational history,expected chemical and physical relationships, andhistorical monitoring results, the plan was updatedagain in October 1997 (LMES 1997b). Under theexisting plan, effluent monitoring is conducted atthree types of locations: (1) treatment facilities,(2) other point-source and area-source discharges,and (3) instream locations. Operational historyand past monitoring results provide a basis forparameters routinely monitored under the plan(Table 6.3).

The radiological monitoring plan alsoaddresses monitoring of the sanitary sewer. TheY-12 Complex is permitted to discharge domesticwastewater to the city of Oak Ridge publiclyowned treatment works under Industrial andCommercial User Wastewater Discharge PermitNo. 1-91. As required by the discharge permit,



Table 6.3. Radiological parameters monitored at the Y-12 Complex in 2001

Parameters Specific isotopes Rationale for monitoring

Uranium isotopes 238U, 235U, 234U, total U,weight % 235U

These parameters reflect the major activity,uranium processing, throughout the history ofY-12 and are the dominant detectableradiological parameters in surface water

Fission and activation products 90Sr, 3H, 99Tc, 137Cs These parameters reflect a minor activity atY-12, processing recycled uranium from reactorfuel elements, from the early 1960s to the late1980s, and will continue to be monitored astracers for beta and gamma radionuclides,although their concentrations in surface waterare low

Transuranium isotopes 241Am, 237Np,238Pu,239/240Pu

These parameters are related to recycle uraniumprocessing. Monitoring has continued becauseof their half-lives and presence in groundwater

Other isotopes of interest 232Th, 230Th, 228Th, 226Ra,228Ra

These parameters reflect historical thoriumprocessing and natural radionuclides necessaryto characterize background radioisotopes

radiological monitoring of this discharge isconducted and reported to the city of Oak Ridge,although there are no city-established limits.Potential sources of radionuclides discharging tothe sanitary sewer have been identified inprevious studies at the Y-12 Complex as part of aninitiative to meet the “as low as reasonablyachievable” goals. The radiological monitoringneeds for the sanitary sewer were reviewed andsummarized in the 1997 update to the plan (LMES1997b).

Radiological monitoring of storm water is alsorequired by the NPDES permit. A comprehensivemonitoring plan has been designed to fully charac-terize pollutants in storm water runoff. The mostrecent revision of this plan was issued inDecember 1998 (LMES 1998) and incorporatesradiological-monitoring requirements. There are77 storm water outfalls and monitoring pointslocated at the Y-12 Complex, and the NPDESpermit requires characterization of a minimum of25 storm water outfalls per year.

6.4.1 Results

Radiological monitoring plan locationssampled in 2001 are noted in Fig. 6.5. Table 6.4identifies the monitored locations, the frequencyof monitoring, and the sum of the percentages of

the DOE derived concentration guides (DCGs) forradionuclides measured in 2001. Radiological datawere well below the allowable DCGs.

In 2001, the total mass of uranium and asso-ciated curies released from the Y-12 Complex atthe easternmost monitoring station, Station 17 onUpper East Fork Poplar Creek, and the western-most monitoring station, at Bear Creek kilometer(BCK) 4.55 (the former NPDES Outfall 304), was218 kg, or 0.108 Ci (Table 6.5). Figure 6.6 illu-strates a 5-year trend of these releases. The totalrelease is calculated by multiplying the averageconcentration (grams per liter) by the averageflow (million gallons per day). Converting unitsand multiplying by 365 days per year yields thecalculated discharge.

The City of Oak Ridge Industrial and Com-mercial User Wastewater Discharge Permit allowsthe Y-12 Complex to discharge wastewater to betreated at the Oak Ridge publicly owned treatmentworks through the East End Sanitary SewerMonitoring Station, also identified as SS-6(Fig. 6.5). Compliance samples are collected atthis location. No single radionuclide in the Y-12contribution to the sanitary sewer exceeded 4% ofthe DCGs. Summed percentages of DCGs calcu-lated from the Y-12 contribution to the sewer areless than one. Results of radiological monitoring



Table 6.4. Summary of Y-12 Complex radiological monitoring plan sample requirements

OutfallNo.

LocationSample

frequencySample type

Sum ofDCGa

percentage

Y-12 Complex wastewater treatment facilities

501 Central Pollution Control Facility 1/week Composite duringbatch operation

2.8

502 West End Treatment Facility 1/week 24-hour composite No flow503 Steam Plant Wastewater Treatment Facility 1/week 24-hour composite No flow512 Groundwater Treatment Facility 1/week 24-hour composite 3.3520 (402)b Steam condensate 1/week Grab 2.4551 Central Mercury Treatment Facility 1/month 24-hour composite 2.3

Other Y-12 Complex point and area source discharges

S17 (301)b Kerr Hollow Quarry 1/month 24-hour composite 2.2S19 (302)b Rogers Quarry 1/month 24-hour composite 1.5

Y-12 Complex instream locations

BCK 4.55 (304)b Bear Creek, plant exit (west) 1/week 7-day composite 4.0Station 17 East Fork Poplar Creek, plant exit (east) 1/week 7-day composite 2.6200 North/south pipes 1/week 24-hour composite 3.3

Y-12 Complex Sanitary Sewer

SS-6 East End Sanitary Sewer Monitoring Station 1/weekc 7-day composite 83.6d

aDCG = the derived concentration guide found in DOE Order 5400.5. bOutfall identifications were changed by the National Pollutant Discharge Elimination System permit effectiveJuly 1, 1995. Former outfall identifications are shown here in parentheses. cGamma emitters are analyzed once per year. dValue due to one measurement with a high margin of error.

Fig. 6.5. Surface water and sanitary sewer radiological sampling locations at the Y-12 Complex.



Table 6.5. Release of uranium fromthe Y-12 Complex to the off-siteenvironment as a liquid effluent,

1997–2001

YearQuantity released

Cia kg

Station 17

1997 0.098 184

1998 0.076 127

1999 0.070 123

2000 0.063 126

2001 0.043 82

Outfall 304

1997 0.116 199

1998 0.091 148

1999 0.096 183

2000 0.093 168

2001 0.065 136

a1 Ci = 3.7E+10 Bq.

Fig. 6.6. Five-year trend of Y-12 Complexrelease of uranium to surface water.

were reported to the city of Oak Ridge in quarterlymonitoring reports.

Table 6.6 presents a summary of 2001 stormwater data that exceeded screening levels. Moredetailed results are given in EnvironmentalMonitoring on the Oak Ridge Reservation: 2001Results (DOE 2002a). (See http://www.ornl.gov/aser.) Uranium remains the dominant radiologicalconstituent and increases during storm flow. Thisincrease is likely due to increased groundwater

flow and storm water runoff from historically con-taminated areas.

6.5 NONRADIOLOGICALLIQUID DISCHARGES—Y-12 COMPLEX SURFACEWATER AND LIQUIDEFFLUENTS

The current Y-12 NPDES permit, issued onApril 28, 1995, and effective on July 1, 1995,requires sampling, analysis, and reporting forapproximately 95 outfalls. Major outfalls arenoted in Fig. 6.7. The number is subject to changeas outfalls are eliminated or consolidated or ifpermitted discharges are added. Currently, Y-12has outfalls and monitoring points in thefollowing water drainage areas: East Fork PoplarCreek, Bear Creek, and several unnamedtributaries on the south side of Chestnut Ridge.These creeks and tributaries eventually drain tothe Clinch River.

Discharges to surface water allowed under thepermit include storm drainage, cooling water,cooling tower blowdown, steam condensate, andtreated process wastewaters, including effluentsfrom wastewater treatment facilities. Groundwaterinflow into sumps in building basements and infil-tration to the storm drain system are also per-mitted for discharge to the creek. The monitoringdata collected by the sampling and analysis ofpermitted discharges are compared to NPDESlimits if a limit exists for each parameter. Someparameters, defined as “monitor only,” have nospecified limits.

The water quality of surface streams in thevicinity of the Y-12 Complex is affected bycurrent and historical legacy operations. Dis-charges from the Y-12 Complex processes flowinto East Fork Poplar Creek before the water exitsthe Y-12 Complex. East Fork Poplar Creek even-tually flows through the city of Oak Ridge to Pop-lar Creek and into the Clinch River. Bear Creekwater quality is affected by area source runoff andgroundwater discharges. The NPDES permitrequires regular monitoring and storm watercharacterization in Bear Creek and several of itstributaries.

http://www.ornl.gov/aser



Table 6.6. Summary of storm water data above screening levels at the Y-12 Complex

ParameterOutfalls

11 17 19 20 41 42 54 99 102 110 114 125 213 S06 S09

Fecal coliform X X X X X

Total suspended solids X X

Zinc X X X X X X X

Copper X X X X

Lead X

Cadmium X

Mercury X X X X

Manganese X

Phosphorus X X X X

Polychlorinated biphenyls X X

Nitrate (nitrogen) X X

Alpha activity X237Np X238U X

Fig. 6.7. Major Y-12 Complex NPDES outfalls.

The effluent limitations contained in thepermit are based on the protection of water qualityin the receiving streams. The permit emphasizesstorm water runoff and biological, toxicological,and radiological monitoring. Some of therequirements in the permit and the status ofcompliance are as follows:

• chlorine limitations based on water qualitycriteria at the headwaters of East Fork PoplarCreek (monitoring ongoing);

• instream pH limitations on tributaries to BearCreek and various other tributaries on thesouth side of Chestnut Ridge (monitoringongoing);

• a radiological monitoring plan requiringmonitoring and reporting of uranium andother isotopes at pertinent locations (seeSect. 6.4);



• implementation of a storm water pollutionprevention plan and sampling andcharacterization of storm water at a minimumof 25 locations per year (see Sect. 6.5.2.);

• a requirement to manage the flow of EastFork Poplar Creek such that a minimum flowof 7 million gal/day is guaranteed by addingraw water from the Clinch River to the head-waters of East Fork Poplar Creek (seeSect. 6.5.4);

• toxicity limitation for the headwaters of EastFork Poplar Creek (see Sect. 6.6); and

• quarterly toxicity testing at the wastewatertreatment facilities and storm drain locations(see Sect. 6.6).

An agreed-to consent order, dated September27, 1999, resolved outstanding appeals to theNPDES permit by deleting mercury monitoringrequirements and instream limits from the permitand deferring them to the ComprehensiveEnvironmental Response, Compensation, andLiability Act (CERCLA) program. The CERCLArecord of decision will define any mercuryremediation requirements for East Fork PoplarCreek. As required, an NPDES permit applicationwas submitted in October 1999, six months priorto the expiration date of the current permit(April 28, 2000). Since April 28, 2000, the Y-12Complex has continued operation under thecurrent permit.

6.5.1 Sanitary Wastewater

Sanitary wastewater from the Y-12 Complexis discharged to the city of Oak Ridge publiclyowned treatment works under Industrial andCommercial Users Wastewater PermitNumber 1-91. Monitoring is conducted under theterms of the permit for a variety of organic andinorganic pollutants. During 2001, the wastewaterflow in this system averaged about587,000 gal/day (2,218,860 L/day).

Compliance sampling is conducted at the EastEnd Sanitary Sewer Monitoring Station (SS-6,Fig. 6.5) weekly. This monitoring station is alsoused for 24-h flow monitoring. As part of the cityof Oak Ridge pretreatment program, city person-

nel use this monitoring station to perform com-pliance monitoring as required by pretreatmentregulations.

6.5.2 Storm Water

The development and implementation of astorm water pollution prevention plan at the Y-12Complex is designed to minimize the discharge ofpollutants in storm water runoff. This planrequires (1) characterization of storm water bysampling during storm events, (2) implementationof measures to reduce storm water pollution,(3) facility inspections, and (4) employee training.

Storm water outfalls at the Y-12 Complex arelocated in subbasins (drainage areas) and areroutinely sampled as required by the NPDESpermit. The outfalls are categorized into fourcategories based on characteristics of the dis-charged water and are grouped within eachcategory based on similarity as to land use of areadrained and possible pollutants. A full chemicaland radiological characterization of the dischargeduring a rain event is not required of all stormwater outfalls each year. Representative samplingis permitted due to similarity within the same out-fall groupings. A minimum of 25 storm wateroutfalls is required to be sampled and charac-terized each year during storm events, includingboth grab and composite sampling.

Each year approximately 1500 chemicalanalyses are conducted on storm water samples atthe Y-12 Complex. By assessing the quality ofstorm water discharges from the site and by deter-mining potential sources of pollutants affectingstorm water, effective controls can be identifiedand put into place to reduce or eliminate thesepollutant sources.

The storm water pollution prevention plan isreviewed at least annually and is updated asnecessary to reflect changes in operations and toincorporate revised monitoring strategies based ondata from past years. The most recent revision ofthis plan was issued in December 1998. The nextrevision is anticipated to be released in CY 2002.



6.5.3 Results and Progress inImplementing CorrectiveActions

In 2001, the Y-12 Complex experienced nineNPDES excursions. There were five excursions in2000, four excursions in 1999, and nine in 1998.Additional details on all Y-12 NPDES permitexcursions recorded in 2001 and the associatedcorrective actions are summarized in Appendix D,Table D.1. Table 6.7 lists the NPDES compliancemonitoring requirements and the 2001 compliancerecord.

During 2001, the Y-12 Complex experiencedno exceedances of the Industrial and CommercialUsers Wastewater Permit for discharge of sanitarywastewater to the city of Oak Ridge publiclyowned treatment works. Table 6.8 lists theIndustrial and Commercial Users WastewaterPermit compliance monitoring requirements andthe 2001 compliance record.

Review of storm water data from past yearsindicates that pollutant loads increase duringstorm events and that water quality may beaffected by uncovered scrap metal storage sites.For example, some outfalls are showing levelsabove screening limits of total suspended solids,fecal coliform, bacteria, polychlorinated biphenyls(PCBs), nitrates, and metals (Pb, Cd, Zn, P, Cu, U,Mn, and Hg) during storm events (see Table 6.6).However, some monitored pollutants are notpresent at specific outfalls. Detailed storm waterdata summary tables are given in EnvironmentalMonitoring on the Oak Ridge Reservation: 2001Results (DOE 2002a). (See http://www.ornl.gov/aser/.)

6.5.4 Flow Management (orRaw Water) Project

Because of concern about maintaining waterquality and stable flow in the upper reaches ofEast Fork Poplar Creek, the NPDES permitrequires addition of Clinch River water to theheadwaters of East Fork Poplar Creek (North/South Pipe-Outfall 200 area) so that a minimumflow of 7 million gal/day (26.5 million L/day) ismaintained at the point where East Fork PoplarCreek leaves the reservation (Station 17). The

permit required that this project be implementedby March 1997, but the work was completedahead of schedule (August 1996). With thecompletion of this project, instream watertemperatures decreased approximately 5EC (fromapproximately 26EC at the headwaters).

During CY 2001 the flow of upper East ForkPoplar Creek was maintained in accordance withthe permit conditions. The average daily flowduring CY 2001 was 8.5 million gal/day.

6.6 BIOMONITORINGPROGRAM

In accordance with the 1995 NPDES permit(Part III-C, p. 39), a biomonitoring program thatevaluates an East Fork Poplar Creek instreammonitoring location (Outfall 201), wastewatertreatment system discharges, and locations in thestorm sewer system is required. Table 6.9 sum-marizes the results of biomonitoring tests con-ducted during 2001 on effluent samples fromwastewater treatment systems and storm drainagesystems. The results of the biomonitoring tests areexpressed as the concentration of effluent that islethal to 50% of the test organisms (LC50) duringa 48-hour period. Thus, the lower the value, themore toxic an effluent. The LC50 is compared tothe effluent’s calculated instream waste concen-tration to determine the likelihood that the dis-charged effluent would be harmful to aquatic lifein the receiving stream. If the LC50 is much greaterthan the instream waste concentration, it is lesslikely that there is an instream impact.

Effluent samples from three of the fourwastewater treatment system discharges weretested at least three times during 2001 usingCeriodaphnia dubia; the West End TreatmentFacility did not release effluents and so was nottested during 2001. With LC50s greater than100%, effluents from the Central PollutionControl Facility were consistently nontoxicthroughout the year. With LC50s greater than100% in three of four tests, effluents from theCentral Mercury Treatment System weregenerally nontoxic as well. The LC50s for effluentfrom the Groundwater Treatment Facility rangedfrom 36.7 to greater than 100%. In all cases thecalculated instream waste concentrations of theeffluent were less than the LC50s, suggesting that

http://www.ornl.gov/aser



Table 6.7. NPDES compliance monitoring requirements and record for the Y-12 ComplexJanuary through December 2001

Discharge point Effluent parameter

Effluent limitsPercentage

ofcompliance

No. ofsamples

Dailyavg

(lb/d)

Dailymax

(lb/d)

Dailyavg

(mg/L)

Dailymax

(mg/L)Outfall 066 pH, standard units a 9.0 b 0Outfall 068 pH, standard units a 9.0 b 0Outfall 117 pH, standard units a 9.0 b 0Outfall 073 pH, standard units

Total residual chlorinea 9.0

0.5100100

77

Outfall 077 pH, standard unitsTotal residual chlorine

a 9.00.5

100100

1212


a 9.00.5

bb

00


a 9.00.5

bb

00


a 9.00.5

100100

1512

Category I outfalls (storm water, steam condensate, cooling tower blowdown, and groundwater)

pH, standard units a 9.0 100 69

Category I outfalls (Outfalls S15 and S16)


Category II outfalls (cooling water, steam condensate, storm water, and groundwater)

pH, standard unitsTotal residual chlorine

a 9.00.5

100100

13983

Category II outfalls (S21, S22, S25, S26, S27, S28, and S29)


Outfall S19 (Rogers Quarry)


Category III outfalls (storm water, cooling water, cooling tower blowdown, steam condensate, and groundwater)

pH, standard unitsTotal residual chlorine

a 9.00.5

100100

173136

Outfall 201 (below the North/South pipes)

Total residual chlorineTemperature, ECpH, standard units 8.5

0.011aa

0.01930.5

99100100

159157157

Outfall 200 (North/ South pipes)

Oil and grease 10 15 99 156



Table 6.7 (continued)



ofcompliance

No. ofsamples

Dailyavg

(lb/d)

Dailymax

(lb/d)

Dailyavg

(mg/L)

Dailymax

(mg/L)Outfall 021 Total residual chlorine

Temperature, ECpH, standard units

0.080a

0.18830.5

9.0

100100100

156158158

Outfall 017 pH, standard unitsAmmonia as N

a32.4

9.064.8

100100

5452

Outfall 055 pH, standard unitsMercuryTotal residual chlorine

a 9.00.0040.5

100100100

104104104

Outfall 55A pH, standard unitsMercury

a 9.00.004

bb

00

Outfall 550 pH, standard unitsMercury

a0.002

9.00.004

100100

5252

Outfall 551 pH, standard unitsMercury

0.002 9.00.004

10092

5252

Outfall 051 pH, standard units a 9.0 99 109Outfall 501 (Central Pollution Control Facility)

pH, standard unitsTotal suspended solidsTotal toxic organicsOil and greaseCadmiumChromiumCopperLeadNickelNitrate/nitriteSilverZincCyanidePolychlorinated biphenyls

0.161.01.20.261.4

0.140.90.4

0.41.72.00.42.4

0.261.60.72

a31.0

100.0750.50.50.12.38

0.051.480.65

9.040.0

2.1315

0.151.01.00.23.98

1000.052.01.200.001

100100100100100100100100100100100100100100

66066666666660

Outfall 502 (West End Treatment Facility)

pH, standard unitsTotal suspended solidsTotal toxic organicsNitrate/nitriteOil and greaseCadmiumChromiumCopperLeadNickelSilverZincCyanidePolychlorinated biphenyls

18.6

0.161.01.20.261.40.140.90.4

36.0

0.41.72.00.42.40.261.60.72

a31.0

10010

0.0750.50.50.102.380.051.480.65

9.040.0

2.13150

150.151.01.00.203.980.052.01.200.001

bbbbbbbbbbbbbb

00000000000000



Table 6.7 (continued)



ofcompliance

No. ofsamples

Dailyavg

(lb/d)

Dailymax

(lb/d)

Dailyavg

(mg/L)

Dailymax

(mg/L)Outfall 503 (Steam Plant Wastewater Treatment Facility)

pH, standard unitsTotal suspended solidsOil and greaseIronCadmiumChromiumCopperLeadZinc

12562.6

4.17

0.834.17

4.17

41783.4

4.17

0.834.17

4.17

a30.010

1.00.0750.200.200.101.0

9.040.015

1.00.150.200.400.201.0

bbbbbbbbb

000000000

Outfall 512 (Groundwater Treatment Facility)

pHIronPolychlorinated biphenyls

a 9.01.00.001

100100100

13013112

Outfall 520 pH, standard units 9.0 100 12Outfall 05A pH 9.0 b 0 aNot applicable. bNo discharge.

Table 6.8. Y-12 Complex Discharge Point SS6, Sanitary Sewer Station 6January through December 2001

Effluent parameterNumber of

samplesDaily average value

(effluent limit)aDaily maximum value

(effluent limit)bPercentage ofcompliance

pH, standard units 54 c 9/6d 100Silver 52 0.05 0.1 100Arsenic 52 0.01 0.015 100Benzene 12 0.01 0.015 100Biochemical oxygen demand 52 200 300 100Cadmium 52 0.0033 0.005 100Chromium 52 0.05 0.075 100Copper 52 0.14 0.21 100Cyanide 12 0.041 0.062 100Iron 52 10 15 100Mercury 52 0.023 0.035 100Kjeldahl nitrogen 52 45 90 100Methylene chloride 12 0.027 0.041 100Nickel 52 0.021 0.032 100Oil and grease 52 25 50 100Lead 52 0.049 0.074 100Phenols—total recoverable 50 0.3 0.5 100Suspended solids 52 200 300 100Toluene 12 0.01 0.02 100Trichloroethene 12 0.018 0.027 100Zinc 52 0.35 0.75 100 aUnits in milligrams per liter unless otherwise indicated. bIndustrial and Commercial Users Wastewater Permit limits. cNot applicable. dMaximum value/minimum value.



Table 6.9. Y-12 Complex Biomonitoring Program summary information for wastewater treatmentsystems and storm sewer effluents for 2001a

Site/buildingTestdate

Species48-h LC50

b

(%)IWCc

(%)

SWHISSd south of 9204-2 1/18/01 Ceriodaphnia 57.8 eSWHISS south of 9204-2 (dechlorinated) 1/18/01 Ceriodaphnia 68.7 eSWHISS south of 9201-4 1/18/01 Ceriodaphnia 70.7 eSWHISS south of 9201-4 (dechlorinated) 1/18/01 Ceriodaphnia >100 eCentral Mercury Treatment System 1/19/01 Ceriodaphnia >100 0.16SWHISS south of 9201-5, 9201-4 (dechlorinated) 1/23/01 Ceriodaphnia 52.1 eGroundwater Treatment Facility 1/23/01 Ceriodaphnia 93.8 0.06SWHISS south of 9201-5, 9201-4 1/23/01 Ceriodaphnia 25.5 eSWHISS south of 9204-4, 9201-5 1/23/01 Ceriodaphnia 70.7 eSWHISS south of 9204-4, 9201-5 (dechlorinated) 1/23/01 Ceriodaphnia >100 eCentral Pollution Control Facility 2/3/01 Ceriodaphnia >100 0.17Storm sewer south of 9201-4 4/19/01 Ceriodaphnia 33.5 eStorm sewer north of 9727-3 4/19/01 Ceriodaphnia >100 eGroundwater Treatment Facility 4/19/01 Ceriodaphnia 36.7 0.11Central Mercury Treatment System 4/20/01 Ceriodaphnia >100 0.14Central Pollution Control Facility 4/21/01 Ceriodaphnia >100 0.13Storm sewer 9215/9204-2E alley (dechlorinated) 4/24/01 Ceriodaphnia >100 eStorm sewer 9215/9204-2E alley 4/24/01 Ceriodaphnia 36.4 eStorm sewer west of 9204-2 (dechlorinated) 4/24/01 Ceriodaphnia >100 eStorm sewer west of 9204-2 4/24/01 Ceriodaphnia 40.9 eLithium Process Steam Condensate 5/24/01 Ceriodaphnia 6.4 eCentral Pollution Control Facility 7/14/01 Ceriodaphnia >100 0.17Groundwater Treatment Facility 7/18/01 Ceriodaphnia 70.6 0.09Storm sewer south of 9201-4 7/19/01 Ceriodaphnia 61.2 eStorm sewer north of 9727-3 7/19/01 Ceriodaphnia >100 eCentral Mercury Treatment System 7/20/01 Ceriodaphnia 60.6 0.18Lithium process steam condensate 7/20/01 Ceriodaphnia 13.0 eStorm sewer west of 9204-2 7/25/01 Ceriodaphnia >100 eStorm sewer west of 9204-2 (dechlorinated) 7/25/01 Ceriodaphnia >100 eStorm sewer 9215/9204-2E alley 7/25/01 Ceriodaphnia 70.7 eStorm sewer 9215/9204-2E alley (dechlorinated) 7/25/01 Ceriodaphnia >100 eLithium process steam condensate 10/2/01 Ceriodaphnia 14.9 eSWHISS south of 9204-2 10/18/01 Ceriodaphnia >100 eSWHISS south of 9201-4 10/18/01 Ceriodaphnia 46.4 eSWHISS south of 9201-4 (dechlorinated) 10/18/01 Ceriodaphnia >100 eSWHISS south of 9204-2 (dechlorinated) 10/18/01 Ceriodaphnia >100 eCentral Mercury Treatment System 10/19/01 Ceriodaphnia >100 0.12Lithium process steam condensate 10/22/01 Ceriodaphnia <6 eSWHISS south of 9201-5, 9201-4 10/23/01 Ceriodaphnia 87.1 eSWHISS south of 9201-5, 9201-4 (dechlorinated) 10/23/01 Ceriodaphnia >100 eSWHISS south of 9204-4, 9201-5 10/23/01 Ceriodaphnia 100 eSWHISS south of 9204-4, 9201-5 (dechlorinated) 10/23/01 Ceriodaphnia >100 eGroundwater Treatment Facility 11/6/01 Ceriodaphnia >100 0.11

aSummarized are the effluents and their corresponding 48-h LC50s and instream waste concentrations.Note: Discharges from treatment facilities are intermittent because of batch operations. bThe concentration of effluent (as a percentage of full-strength effluent diluted with laboratory controlwater) that is lethal to 50% of the test organisms in 48 h. cIWC = instream waste concentration based on actual flows at Outfall 201 in East Fork Poplar Creek. dSWHISS = Surface Water Hydrological Information Support System. eThis point is in the storm sewer system; therefore, an IWC is not applicable.



Table 6.10. Y-12 Complex Biomonitoring Program summary informationfor Outfall 201 for 2001a

Site Test date SpeciesNOECb

(%)96-h LC50

c

(%)

Outfall 201 1/17 CeriodaphniaFathead minnow

100100

>100>100


100100

>100>100


100100

>100>100


100100

>100>100

aSummarized are the no-observed effect concentrations and the 96-h LC50s for theinstream monitoring location, Outfall 201. bNo-observed-effect concentration (NOEC) as a percent of full-strength effluentfrom Outfall 201 diluted with laboratory control water. The NOEC must equal one ofthe test concentrations and is the concentration that does not reduce Ceriodaphniasurvival or reproduction or fathead minnow survival or growth. cThe concentration of effluent (as a percentage of full-strength effluent diluted withlaboratory control water) that is lethal to 50% of the test organisms in 96 h.

effluents from the individual treatment facilitieswould not be acutely toxic to the aquatic life ofEast Fork Poplar Creek.

Various locations in the storm drainagesystem upstream of outfalls 200 and 201 were alsomonitored during the year. When chlorine wasdetected in a storm sewer sample, side-by-sidetests were conducted with a sample that wasdechlorinated. In all cases where toxicity wasdetected in the dechlorinated sample (LC50 notgreater than 100%), survival was higher in thedechlorinated sample than in the nontreatedsample. The improvement in survival varied fromsample to sample (as indicated by an increase inthe LC50), indicating that the toxicity fromchlorine varied from sample to sample. In mostcases, the full-strength dechlorinated samplecontinued to reduce Ceriodaphnia survival,indicating sources of toxicity other than chlorine.Because flow is not measured at these storm-sewer points, it is not possible to know thecontribution of each to the total flow at Outfall201 (i.e, the instream waste concentration). It isnotable, however, that the results of thebiomonitoring tests at Outfall 201 (Table 6.10)demonstrated that when all discharges werecombined (treated effluent, storm sewercontribution, plus flow management water) theresult was a consistent absence of toxicity atOutfall 201.

Table 6.10 summarizes the “no-observed-effect concentrations” and 96-hour LC50s for theinstream monitoring location Outfall 201. The no-observed-effect concentration is the concentrationof effluent that does not reduce survival, growth,or reproduction of the biomonitoring testorganisms during a 6- or 7-day test. Thus, like theLC50, the lower the value, the more toxic theeffluent. Water from the instream monitoringpoint, Outfall 201, was tested four times in 2001using fathead minnow larvae (pimephalespromelas) and Ceriodaphnia dubia. The no-observed-effect concentrations were 100% for allCeriodaphnia and fathead minnow tests; the96-hour LC50s were consistently greater than100% for both Ceriodaphnia and fatheadminnows.

6.7 BIOLOGICAL MONITORINGAND ABATEMENTPROGRAMS

The NPDES permit issued to the Y-12National Security Complex in 1995 mandates aBiological Monitoring and Abatement Program(BMAP) with the objective of demonstrating thatthe effluent limitations established for the facilityprotect the classified uses of the receiving stream,East Fork Poplar Creek. The BMAP consists of



four major tasks that reflect complementaryapproaches to evaluating the effects of Y-12Complex discharges on the aquatic integrity ofEast Fork Poplar Creek. These tasks are(1) toxicity monitoring, (2) biological indicatorstudies, (3) bioaccumulation studies, and(4) ecological surveys of the periphyton, benthicmacroinvertebrate, and fish communities.

Trends of increases in species richness anddiversity at upstream locations over the lastdecade, along with similar but more subtle trendsin a number of other BMAP indicators, demon-strate that the overall ecological health of EastFork Poplar Creek continues to improve. How-ever, the pace of improvement in the health ofEast Fork Poplar Creek has slowed in recentyears, and fish and invertebrate communities con-tinue to be degraded in comparison with similarcommunities in reference streams.

6.7.1 Toxicity Monitoring

Toxicity monitoring employs EPA-approvedmethods with Ceriodaphnia dubia and fatheadminnows to provide systematic information that isused to verify biological water quality of EastFork Poplar Creek at intervals throughout theyear. Ceriodaphnia tests were conducted quarterlyin 2001 for one site upstream of Bear Creek Road[East Fork Poplar Creek kilometer (EFK) 24.1]. Inaddition, quarterly toxicity tests with both fatheadminnows and Ceriodaphnia were conducted atOutfall 201 as required by the Y-12 Complex’sNPDES permit. Because of the close proximity ofOutfall 201 (an instream NPDES location in upperEast Fork Poplar Creek) to EFK 25.1, the tests ofwater from Outfall 201 also met the intent of theY-12 BMAP Plan (Adams et al. 2000) to conductquarterly toxicity tests at the latter location.

No evidence for toxicity was observed in anyof the 2001 Ceriodaphnia tests (both East ForkPoplar Creek sites) or fathead minnow tests(Outfall 201). These results are consistent with thefindings of previous Ceriodaphnia and fatheadminnow tests conducted since flow managementbegan in the latter half of 1996. These resultscontrast, however, with the continuing toxicityevident in chronic tests involving fish embryosand clams, which appear more sensitive to waterquality conditions in East Fork Poplar Creek. Fish

embryo-larval test results are discussed inSect. 6.7.3; clam tests are discussed in Sect. 6.7.4.

6.7.2 Bioaccumulation Studies

Mercury and PCBs were historically elevatedin East Fork Poplar Creek fish relative to fish inuncontaminated reference streams. Fish are moni-tored regularly in East Fork Poplar Creek formercury and PCBs to assess spatial and temporaltrends in bioaccumulation associated with on-going remedial activities and plant operations. Aspart of this monitoring effort, redbreast sunfish(Lepomis auritus) were sampled twice during2001 from the mid to upper reaches of East ForkPoplar Creek and were analyzed for tissue concen-trations of these two environmental contaminants.Largemouth bass (Micropterus salmoides) werecollected once in 2001 from two sites in East ForkPoplar Creek (Lake Reality and EFK 23.4) tomonitor maximum bioaccumulation in largerpiscivorous fish of the system.

Mercury concentrations remained muchhigher during 2001 in fish from East Fork PoplarCreek as compared with fish from referencestreams. Elevated mercury concentrations inUpper East Fork Poplar Creek fish indicate thatthe Y-12 Complex remains a continuing source ofmercury to fish in the stream. Following signifi-cant decreases in the mid-1990s, mercury concen-trations in water in Upper East Fork Poplar Creekhave continued to fall, although less dramaticallyin recent years, while mercury concentrations infish have remained relatively constant over thelast several years (Fig. 6.8).

PCB concentrations in East Fork Poplar Creeksunfish fell during 2001 within ranges typical ofpast monitoring efforts at these sites (Fig. 6.9).Mean PCB concentrations were again highest inLake Reality and above Lake Reality, indicatinga continuing PCB source or sources within theY-12 Complex.

6.7.3 Biological IndicatorStudies

The biological indicator task is designed toevaluate the effects of water quality and otherenvironmental variables on the health and repro-ductive condition of individual fish and fish



Fig. 6.8. Semiannual average mercury concentrations in muscle fillets of redbreast sunfish andwater in East Fork Poplar Creek at Station 17 through spring 2001.

Fig. 6.9. Mean concentrations of PCBs in redbreast sunfish muscle fillets in East Fork PoplarCreek at Station 17 through spring 2001.



Fig. 6.10. Comparison of mean abundance of sensitive fish species collected during each yearfrom 1985 through 2001 from four sites in East Fork Poplar Creek and a reference site (Brushy Fork).Results for an additional site in Upper East Fork Poplar Creek (EFK 24.4) and a second reference site (HindsCreek) are not shown.

populations in East Fork Poplar Creek. Redbreastsunfish were sampled from three sites in East ForkPoplar Creek and from two reference streams inthe spring of 2001 prior to the onset of thebreeding season. Overall trends in many con-tamination-related bioindicators suggest that therehas been a distinct improvement in overall fishhealth in Upper East Fork Poplar Creek in recentyears. However, the health and reproductive con-dition of sunfish from East Fork Poplar Creeksites upstream of Bear Creek remains lower thanin fish from reference sites or even downstreamEast Fork Poplar Creek sites.

East Fork Poplar Creek water was toxic to fishembryos in the medaka embryo-larval test fordevelopmental toxicity during 2001, althoughtoxicity was significantly less than in previousyears’ tests. An explanation for this toxicity hasyet to be identified, but medaka embryos, like theembryos of other fish species, are quite sensitiveto many of the chemical constituents originatingwithin the Y-12 Complex, including variousmetals (particularly mercury), ammonia and other

nitrogenous wastes, and even the chemical by-products of chlorination/dechlorination watertreatment procedures.

6.7.4 Ecological Surveys

Periphyton were monitored quarterly during2001 from three sites along East Fork PoplarCreek. Algal biomass and photosynthetic ratesremained higher than in reference streams. Con-centrations of various metals continued to beelevated in periphyton.

Fish communities were monitored twice in2001 at five sites along East Fork Poplar Creekand at two reference streams. In recent years,overall species richness and the number of pollu-tion-sensitive fish species have increased at allsampling locations below Lake Reality(Fig. 6.10). However, fish communities in EastFork Poplar Creek continue to lag behindreference stream communities in these and otherimportant metrics of community health.



Fig. 6.11. Total taxonomic richness (mean number of taxa/sample) andtotal taxonomic richness of the Ephemeroptera, Plecoptera, and Trichoptera(mean number of EPT taxa/sample) of the benthic macroinvertebratecommunities in East Fork Poplar Creek and two reference sites, one onBrushy Fork and one on Hinds Creek (BFK 7.6 and HCK 20.6), spring dataonly. (EPT taxa include relatively pollution-sensitive species.)

Benthic macroinvertebrate communities weremonitored at three sites in East Fork Poplar Creekand at two reference streams in the spring and fallof 2001. The macroinvertebrate communities atEFK 23.4 and EFK 24.4 remained significantlydegraded as compared with reference communi-ties (Fig. 6.11). Increases in total richness and therichness of pollution-tolerant taxa continue at theEast Fork Poplar Creek sites, although the pace ofimprovement in benthic macroinvertebrate com-munities has slowed in recent years.

The effects of in situ exposure on clamgrowth and survival were tested during 2001 atthree sites in East Fork Poplar Creek and at three

reference streams. As in similar tests conducted inprevious years, clam survival was significantlyimpacted at EFK 23.4 and EFK 24.4, and growthwas decreased at all tested East Fork Poplar Creeksites.

6.8 Y-12 COMPLEX AMBIENTSURFACE WATERMONITORING

Routine surface water surveillance moni-toring, above and beyond that required by theNPDES permit, is performed as a best manage-



Fig. 6.12. Locations of Y-12 Complex surface water surveillance sampling stations.

ment practice. The Y-12 Environmental Com-pliance Department staff monitor the surfacewater as it exits from each of the three hydro-geologic regimes that serve as an exit pathway forsurface water (Fig. 6.12).

Monitoring is conducted in East Fork PoplarCreek at Station 17 (9422-1) near the junction ofScarboro and Bear Creek roads. The currentsampling program consists of two 48-h com-posites plus a 3-day weekend composite. Thesesamples are analyzed for mercury, ammonia-N,inductively coupled plasma (ICP) metals, and totalsuspended solids.

Monitoring is conducted in Bear Creek atBCK 4.55 (former NPDES Station 304), which isat the western boundary of the Y-12 Complex areaof responsibility. A surveillance sample (a 7-daycomposite sample) is collected monthly foranalysis for mercury; anions (sulfate, chloride,nitrate, nitrite); ICP metals; total phenols; andtotal suspended solids.

The exit pathway from the Chestnut RidgeHydrogeologic Regime is monitored via NPDESlocation S19 (former NPDES Station 302) atRogers Quarry. S19 is an instream location ofMcCoy Branch and is sampled monthly (a 24-hcomposite) for ICP metals. The NPDES require-

ment for this location is to monitor and reportmetals data only.

In addition to these exit pathway locations, anetwork of real-time monitors is located atinstream locations along Upper East Fork PoplarCreek and at key points on the storm drain systemthat flows to the creek. The Surface WaterHydrological Information Support System is avail-able for real-time water quality measurements,such as pH, temperature, dissolved oxygen, con-ductivity, and chlorine. The locations are noted inFig. 6.13. Not all locations or parameters are oper-ated on a routine basis.

For nonradiological parameters that aresampled and detected above the analytical methodreporting detection limit, the data are comparedwith Tennessee water quality criteria. The mostrestrictive of either the freshwater fish and aquaticlife criterion maximum concentration or therecreation concentration for organisms onlystandard (105 risk factor for carcinogens) is used.This comparison serves as a record of waterquality, and the comparison to state water qualitycriteria limits is for informational purposes only;as such, no attempt is made to achieve the lowestpossible detection limit for all parameters.



Fig. 6.13. Surface Water Hydrological Information Support System monitoring locations.

More than 5400 surface water surveillancesamples were collected in 2001. Comparisonswith Tennessee water quality criteria indicate thatonly mercury, copper, and zinc from samplescollected at Station 17 were detected at valuesexceeding a criteria maximum. Results are shownin Table 6.11. Of all the parameters measured inthe surface water as a best management practice,mercury is the only demonstrated contaminant ofconcern.

Additional surface-water sampling is con-ducted on Bear Creek in accordance with the Y-12Groundwater Protection Program to monitortrends throughout the Bear Creek HydrogeologicRegime (see Sect. 6.10.3.3).

6.9 Y-12 SEDIMENT SAMPLING

Historical data have shown that mercury,PCBs, and isotopes of uranium are present atdetectable levels in sediment. Therefore, as a bestmanagement practice, the Y-12 Complex main-tains an annual sampling program to determinewhether these constituents are accumulating in thesediments of East Fork Poplar Creek and BearCreek as a result of Y-12 Complex discharges.Results of the most recent monitoring activity aregiven in Table 6.12. The monitoring results indi-cate that the levels of mercury, PCBs, andisotopes of uranium and thorium have not signif-icantly changed.

This activity is also used to comply with DOEOrder 5400.5, which states in Chapter II.3.a.2 thatmeasures be taken to prevent the buildup ofradionuclides in sediments caused by releases of

waste streams to natural waterways. The orderlimits the amount of activity that may be presentin released settleable solids. Because wastestreams from the Y-12 Complex have very lowsettleable-solid contents, this sampling program tomeasure activity in the sediments of East ForkPoplar Creek and Bear Creek is used to determinewhether a buildup of radionuclide concentrationsis occurring.

6.10 GROUNDWATER MONI-TORING AT THE Y-12COMPLEX

More than 200 sites have been identified atthe Y-12 Complex that represent known orpotential sources of contamination to theenvironment as a result of past waste managementpractices. Figure 6.14 depicts the major facilitiesconsidered as known and/or potential contaminantsource areas for which groundwater monitoringwas performed during CY 2001. Because of thiscontamination, extensive groundwater monitoringis required to comply with regulations and DOEorders.

During CY 2001, routine groundwater moni-toring at Y-12 was conducted by two programs,the Y-12 Groundwater Protection Program, man-aged by BWXT Y-12 L.L.C., and the WaterResources Restoration Program, managed by BJC.Each program is responsible for monitoringgroundwater to meet specific compliance require-ments. In CY 2001, the Groundwater ProtectionProgram performed monitoring to comply with



Table 6.12. Results of Y-12 Complex sediment monitoring

Parameter 1999 +/– MDAa 2000 +/– MDA 2001 +/– MDA

Station 17226Ra (pCi/g) 2.4 0.31 0.026 –0.67 0.48 0.30 –0.020 0.91 0.065228Th (pCi/g) 0.57 0.082 0.022 0.072 0.15 0.27 0.039 0.056 0.098230Th (pCi/g) 0.50 0.074 0.008 0.79 0.3 0.16 0.11 0.064 0.062232Th (pCi/g) 0.48 0.077 0.003 0.10 0.099 0.13 0.042 0.043 0.062234U (pCi/g) 2.7 0.29 0.002 1.4 0.19 0.017 1.5 0.26 0.063235U (pCi/g) 0.11 0.025 0.003 0.078 0.03 0.007 0.050 0.041 0.023238U (pCi/g) 2.8 0.3 0.006 3 0.37 0.014 1.2 0.22 0.044Mercury (µg/g) 14.6 18.5 6.67Total polychlorinated biphenyls (µg/kg)

280 180 270

BCK 9.4226Ra (pCi/g) 2.5 0.24 0.057 0.92 0.5 0.41 1.0 0.77 0.075228Th (pCi/g) 0.52 0.065 0.009 0.54 0.19 0.16 0.51 0.13 0.038230Th (pCi/g) 0.24 0.034 0.004 0.38 0.15 0.11 0.21 0.075 0.016232Th (pCi/g) 0.41 0.058 0.002 0.28 0.13 0.078 0.41 0.11 0.016234U (pCi/g) 3.6 0.45 0.020 3.5 0.42 0.016 1.1 0.21 0.083235U (pCi/g) 0.20 0.059 0.010 0.16 0.047 0.0079 0.11 0.061 0.022238U (pCi/g) 7.6 0.89 0.008 6.7 0.77 0.0064 2.5 0.37 0.042Mercury (µg/g) 0.215 0.262 0.187Total polychlorinated biphenyls (µg/kg)

350 340 550

aMinimum detectable activity.

Table 6.11. Surface water surveillance measurements exceeding Tennessee water quality criteriaat the Y-12 Complex, 2001

Parameterdetected

LocationNumber of

samples

Concentration (mg/L) Water qualitycriteria(mg/L)

Number ofmeasurements

exceeding criteriaDetection

limitMax Avg

Copper Station 17 150 0.02 <0.08 <0.02 0.0177 2

Mercury Station 17 398 0.00021 0.0053 <0.0005 0.000051 369

Zinc Station 17 150 0.05 0.208 <0.05 0.117a 1

aThe standard is a function of total hardness. This value corresponds to a total hardness value of 100 mg/L.

DOE orders, while the Water Resources Restora-tion Program performed groundwater monitoringin compliance with CERCLA, RCRA, and TDECDivision of Solid Waste Management regulations.

Although the Groundwater ProtectionProgram and the Water Resources RestorationProgram have differing technical objectives andresponsibilities, considerable efforts are made tomaintain consistency in groundwater monitoring

activities at the Y-12 Complex. Communicationbetween the two programs has been crucial ineliminating any redundancies in monitoringactivities. In addition, communication and mutualcooperation provided for more consistent andefficient data collection, evaluation, and overallquality. All groundwater monitoring data obtainedby both programs is evaluated to provide com-prehensive reporting by the GroundwaterProtection Program.



Fig. 6.14. Known or potential contaminant sources for which groundwater monitoring was performedduring CY 2001.

6.10.1 Hydrogeologic Setting

The Y-12 Complex is divided into threehydrogeologic regimes, which are delineated bysurface water drainage patterns, topography, andgroundwater flow characteristics. The regimes arefurther defined by the waste sites they contain.These regimes include the Bear Creek Hydro-geologic Regime, the Upper East Fork PoplarCreek Hydrogeologic Regime, and the ChestnutRidge Hydrogeologic Regime (Fig. 6.15). Most ofthe Bear Creek and Upper East Fork Poplar Creekregimes are underlain by the ORR Aquitards. Theextreme southern portion of these two regimes isunderlain by the Maynardville Limestone, whichis part of the Knox Aquifer. The entire ChestnutRidge regime is underlain by the Knox Aquifer(Fig. 1.6).

In general, groundwater flow in the watertable interval follows topography. Shallowgroundwater flow in the Bear Creek regime andthe Upper East Fork regime is divergent from atopographic and groundwater table divide locatednear the western end of the Y-12 Complex. Theflow directions of shallow groundwater east andwest of the divide are predominantly easterly andwesterly, respectively. This divide defines the

boundary between the Bear Creek and Upper EastFork regimes. In addition, flow converges towardthe primary surface streams from Pine Ridge andChestnut Ridge. In the Chestnut Ridge regime, agroundwater table divide exists that approxi-mately coincides with the crest of the ridge.Shallow groundwater flow, therefore, tends to betoward either flank of the ridge, with dischargeprimarily to surface streams and springs located inBethel Valley to the south and Bear Creek Valleyto the north.

In Bear Creek Valley, groundwater in theintermediate and deep intervals moves predomin-antly through fractures in the ORR Aquitards,converging toward and moving through fracturesand solution conduits in the Maynardville Lime-stone. Karst development in the MaynardvilleLimestone has a significant impact on ground-water flow paths in the water table andintermediate intervals. In general, groundwaterflow parallels the valley and geologic strike.Groundwater flow rates in Bear Creek Valley varywidely; they are very slow within the deepinterval of the ORR aquitards but can be quiterapid within solution conduits in the MaynardvilleLimestone.



Fig. 6.15. Hydrogeologic regimes at the Y-12 Complex.

The rate of groundwater flow perpendicular togeologic strike from the ORR aquitards to theMaynardville Limestone has been estimated to bevery slow below the water table interval. Mostcontaminant migration appears to be via surfacetributaries to Bear Creek or along utility tracesand buried tributaries in the Upper East Forkregime. In the Bear Creek regime, strike-paralleltransport of some contaminants can occur withinthe ORR aquitards for significant distances.Continuous elevated levels of nitrate within theORR Aquitards are known to extend east and westfrom the S-3 Site for thousands of feet. Volatileorganic compounds at source units in the ORRAquitards, however, tend to remain close tosource areas because they tend to adsorb to thebedrock matrix, diffuse into pore spaces withinthe matrix, and degrade prior to migrating to exitpathways, where rapid transport for long distancesdoes occur. Regardless, extensive volatile organiccompound contamination occurs throughoutgroundwater in both the Bear Creek and UpperEast Fork regimes.

Groundwater flow in the Chestnut Ridgeregime is almost exclusively through fractures andsolution conduits in the Knox Group. Dischargepoints for intermediate and deep flow are not wellknown. Groundwater is currently presumed toflow primarily toward Bear Creek Valley to thenorth and Bethel Valley to the south. Groundwaterfrom intermediate and deep zones may dischargeat certain spring locations along the flanks ofChestnut Ridge. Following the crest of the ridge,water table elevations decrease from west to east,

demonstrating an overall easterly trend in ground-water flow.

6.10.2 CY 2001 MonitoringProgram

Groundwater monitoring in CY 2001 wasperformed to comply with DOE Orders and regu-lations by the Groundwater Protection Programand Water Resources Restoration Program. Com-pliance requirements were met by the monitoringof 153 wells, 18 springs, and 36 surface waterlocations (Table 6.13). Figure 6.16 shows thelocations of ORR perimeter/exit pathway ground-water monitoring stations as specified in the ORREnvironmental Monitoring Plan.

Comprehensive water quality results of moni-toring activities at Y-12 in CY 2001 are presentedin the annual Groundwater Monitoring Report(BWXT Y-12 2002).

Details of monitoring efforts performedspecifically for CERCLA baseline andremediation evaluation are published in the FY2001 and FY 2002 Water Resources RestorationProgram Sampling and Analysis Plans (BJC2000b and BJC 2001b) and the 2002 RemediationEffectiveness Report (DOE 2002b).

Groundwater monitoring compliancereporting to meet RCRA post-closure permitrequirements can be found in the RCRA annualreports (BJC 2002b, BJC 2002c, and BJC 2002d).



Table 6.13. Types and numbers of groundwater monitoring stations sampled at the Y-12Complex during CY 2001

Bear Creek Chestnut RidgeUpper East Fork

Poplar CreekTotal

Conventional wells 56 48 48 152

Multiport wells 0 0 1 1

Surface water 19 7 10 36

Springs 7 9 2 18

Total number of monitoring stations 82 64 61 207

Fig. 6.16. Locations of ORR perimeter/exit pathway well, spring, and surface water monitoring stations inthe Environmental Monitoring Plan for the Oak Ridge Reservation.

6.10.3 Y-12 GroundwaterQuality

Historical monitoring efforts have shown thatfour types of contaminants have affected ground-water quality at Y-12: nitrate, volatile organiccompounds, metals, and radionuclides. Of these,nitrate and volatile organics are the most wide-spread. Some radionuclides, particularly uraniumand 99Tc, are significant, principally in the BearCreek regime and the western and central portionsof the Upper East Fork regime. Trace metals, theleast extensive groundwater contaminants, gener-ally occur in a small area of low-pH groundwaterat the western end of Y-12, near the S-2 and S-3

Sites. Historical data have shown that plumesfrom multiple source units have mixed with oneanother and that contaminants (other than nitrateand 99Tc) are no longer easily associated with asingle source.

6.10.3.1 Upper East Fork PoplarCreek HydrogeologicRegime

The Upper East Fork regime contains conta-minant source areas and surface water andgroundwater components of the hydrogeologicsystem within the production complex and UnionValley to the east and off the ORR. Among thethree hydrogeologic regimes at Y-12, the UpperEast Fork regime encompasses most of the known



Table 6.14. History of waste management units and underground storage tanks included in CY 2001groundwater monitoring activities, Upper East Fork Poplar Creek Hydrogeologic Regimea

Site Historical data

New Hope Pond Built in 1963. Regulated flow of water in Upper East Fork Poplar Creek before exitingthe Y-12 Complex grounds. Sediments include PCBs, mercury, and uranium but nothazardous according to toxicity characteristic leaching procedure. Closed under RCRAin 1990

Salvage Yard ScrapMetal Storage Area

Used from 1950 to present for scrap metal storage. Some metals contaminated withlow levels of depleted or enriched uranium. Runoff and infiltration are the principalrelease mechanisms to groundwater

Salvage Yard Oil/Solvent Drum StorageArea

Primary wastes included waste oils, solvents, uranium, and beryllium. Both closedunder RCRA. Leaks and spills represent the primary contamination mechanisms forgroundwater

Salvage Yard OilStorage Tanks

Used from 1978 to 1986. Two tanks used to store PCB-contaminated oils, both withina diked area

Salvage Yard DrumDeheader Facility

Used from 1959 to 1989. Sump tanks 2063-U, 2328-U, and 2329-U received residualdrum contents. Sump leakage is a likely release mechanism to groundwater

Building 81-10 Area Staging facility. Potential historical releases to groundwater from leaks and spills ofliquid wastes or mercury

Rust Garage Area Former vehicle and equipment maintenance area, including four former petroleumUSTs. Petroleum product releases to groundwater are documented

9418-3 Uranium OxideVault

Originally contained an oil storage tank. Used from 1960 to 1964 to dispose ofnonenriched uranium oxide. Leakage from the vault to groundwater is the likely releasemechanism

Fire Training Facility Used for hands-on fire-fighting training. Sources of contamination to soil includeflammable liquids and chlorinated solvents. Infiltration is the primary releasemechanism to groundwater

Beta-4 Security Pits Used from 1968 to 1972 for disposal of classified materials, scrap metals, and liquidwastes. Site is closed and capped. Primary release mechanism to groundwater isinfiltration

S-2 Site Used from 1945 to 1951. An unlined reservoir received liquid wastes. Infiltration is theprimary release mechanism to groundwater

Waste CoolantProcessing Area

Used from 1977 to 1985. Former biodegradation facility used to treat waste coolantsfrom various machining processes. Closed under RCRA in 1988

Coal Pile Trench Located beneath the current steam plant coal pile. Disposals included solid materials(primarily alloys). Trench leachate is a potential release mechanism to groundwater

aAbbreviationsPCB = polychlorinated biphenyl.RCRA= Resource Conservation and Recovery Act.UST = underground storage tank.

and potential sources of surface and groundwatercontamination. A brief description of waste mana-gement sites is given in Table 6.14. Chemicalconstituents from the S-3 Site (primarily nitrateand 99Tc) dominate groundwater contamination inthe western portion of the Upper East Forkregime, while groundwater in the eastern portion,including Union Valley, is predominantly conta-minated with volatile organics.

Plume Delineation

The primary groundwater contaminants in theUpper East Fork regime are nitrates, volatileorganic compounds, trace metals, and radio-nuclides. Sources of these contaminants moni-tored during CY 2001 are the S-2 Site, the FireTraining Facility, the S-3 Site, the Waste CoolantProcessing Facility, the 9418-3 Uranium Oxide



Fig. 6.17. Nitrate (as N) observed in groundwater at the Y-12 Complex.

Vault, petroleum underground storage tanks, NewHope Pond, Beta-4 Security Pits, Salvage Yard,and process/production buildings throughout theY-12 Complex. Although it is located west of thecurrent hydrologic divide that separates the UpperEast Fork regime from the Bear Creek regime, theS-3 Site, now closed under RCRA, has con-tributed to groundwater contamination in thewestern part of this regime.

Nitrate

Nitrate concentrations in groundwater at Y-12exceed the 10 mg/L maximum drinking watercontamination level (a complete list of nationaldrinking water standards is presented inAppendix C) in a large part of the western portionof the Upper East Fork regime (Fig. 6.17). Thetwo primary sources of nitrate contamination arethe S-3 and S-2 Sites. In CY 2001, Groundwatercontaining nitrate concentrations as high as11,800 mg/L (Well GW-108) occurred in theunconsolidated zone and at shallow bedrockdepths just east of the S-3 Site. These results areconsistent with results in previous years. Theextent of the nitrate plume is essentially defined inthe unconsolidated zone and the shallow bedrockzone. From data collected from monitoring wellsand surface water outfalls during CY 2001 in the

aquitard and aquifer, nitrate concentrations abovethe drinking water standards are observed about4500 ft (1372 m) eastward from the S-3 Site. Thisis approximately 2000 ft (610 m) further east thanwas reported in CY 2000 annual site environ-mental report. This is not an indication ofdramatic migration over the past year, but rathera product of obtaining additional water qualityresults from Well GW-698 at the Building 81-10site during CY 2001. This well was sampled twiceduring CY 2001 with a maximum nitrate concen-tration of 221 mg/L. All of the nitrate resultsindicate that the nitrate plume at the Y-12Complex has remained relatively static.

Trace Metals

Concentrations of barium, beryllium,cadmium, copper, lead, mercury, nickel, selenium,thallium, and uranium exceeded drinking waterstandards during CY 2001 in samples collectedfrom various monitoring wells and surface waterlocations downgradient of the S-2 Site, the S-3Site, the Salvage Yard, and throughout the com-plex. In December 2000, the EPA promulgated adrinking water standard of 0.03 mg/L for uranium.Even though it will not go into effect until 2003,this standard was used to evaluate uranium con-centrations in groundwater and surface water at



Fig. 6.18. Summed volatile organic compounds in groundwater at the Y-12 Complex.

the Y-12 Complex. Concentrations of uraniumexceed this standard in a number of source areas(e.g., the production areas and the Uranium OxideVault) and contribute this trace metal to UpperEast Fork Poplar Creek. The trace metalstrontium, which has no drinking water standard,was also observed at significant concentrations.Elevated concentrations of these metals in ground-water were most commonly observed frommonitoring wells in the unconsolidated zone.Trace metals above standards tend to occuradjacent to the source areas due to low solubilityin natural water systems on the ORR. However,some metals, such as uranium and mercury, arebeing transported through the surface watersystem and have been observed in concentrationsabove the drinking water standards.

Volatile Organic Compounds

Because of the many source areas, volatileorganic compounds are the most widespreadgroundwater contaminants in the East Forkregime. Dissolved volatile organics in the regimeprimarily consist of chlorinated solvents andpetroleum hydrocarbons. In CY 2001, the highestconcentrations of dissolved chlorinated solvents(about 5460 µg/L) were found in groundwater atWell GW-656, near production facilities in thewestern portion of the Y-12 Complex (Fig. 6.18).The highest dissolved concentration of petroleum

hydrocarbons obtained in CY 2001 (about117 µg/L at Well GW-193) occurred in ground-water at a closed underground storage tank east ofBuilding 9201-1 in the central portion of Y-12.

Concentrations of chlorinated volatileorganics near source areas have remainedrelatively constant or have decreased since 1988(Fig. 6.19). Within the exit pathway, wells west ofNew Hope Pond (e.g., GW-605, GW-606)continue to show a shallow, decreasing concen-tration trend (Fig. 6.20). Some monitoring loca-tions (e.g., GW-151) south and east of New HopePond have shown increasing concentrations ofvolatile organics, while those farther to the east(GW-170) show a static trend or decreasingtrends. Evaluations of all of these concentrationtrends indicate a center of mass of the carbontetrachloride plume south of Building 9720-6 thatis moving east. Data show that volatile organicsare most extensive in shallow groundwater.However, when contaminants migrate into theMaynardville Limestone, they tend to concentrateat depths between 100 and 500 ft. The highestconcentrations of volatile organics at the east endof Y-12 appear to be between 200 and 500 ft, asexemplified by vertical carbon tetrachloridedistribution (Fig. 6.21).

The CY 2001 monitoring results generallyconfirm findings from the previous years of moni-toring. A continuous dissolved plume of volatileorganics in groundwater in the bedrock zone



Fig. 6.19. Volatile organic compound concentrations in groundwater in selected wells near source areasin the Upper East Fork Poplar Creek Hydrogeologic Regime.

extends eastward from the S-3 Site over the entirelength of the regime (Fig. 6.18). The primarysources are the Waste Coolant Processing Facilityand production areas throughout the Y-12Complex.

Chloroethene compounds (tetrachloroethene,trichloroethene, dichloroethene, and vinylchloride) tend to dominate the volatile organicplume composition in the western and centralportions of Y-12. However, tetrachloroethene andisomers of dichloroethene are almost ubiquitousthroughout the extent of the plume, indicatingmany source areas. Chloromethane compounds(carbon tetrachloride, chloroform, and methylenechloride) are the predominant volatile organics inthe eastern portion of Y-12.

Radionuclides

The primary alpha-emitting radionuclidesfound in the East Fork regime during CY 2001 areisotopes of uranium. Groundwater with grossalpha activity greater than 15 pCi/L (the drinkingwater standard) occurs in scattered areas through-out the East Fork regime (Fig. 6.22). Historicaldata show that gross alpha activity consistentlyexceeds the drinking water standard and is mostextensive in groundwater in the unconsolidatedzone in the western portion of Y-12 near the S-3Site. However, the highest level of gross alphaactivity (685 pCi/L) observed during CY 2001was observed in groundwater from Well GW-154,west of the Former Oil Skimmer Basin. Otherareas of elevated gross alpha activity are presentwithin the production areas in the western portion



Fig. 6.20. Summed volatile organic compound concentrations in selected wells near New Hope Pond andexit pathway wells.

of Y-12, near the S-2 Site, and east of the 9418-3Uranium Oxide Vault.

The primary beta-emitting radionuclideobserved in the East Fork regime during CY 2001is 99Tc. Elevated gross beta activity in ground-water in the East Fork regime shows a patternsimilar to that observed for gross alpha activity

(Fig. 6.23). In general, gross beta activity con-sistently exceeds the annual average screeninglevel of 50 pCi/L in groundwater in the westernportion of the regime, with the primary sourcebeing the S-3 Site.

Anomalous gross alpha and gross beta radio-logical results were observed in a single sampling



Fig. 6.21. Maximum carbon tetrachloride concentrations in Maynardville Limestone at depths between200 and 500 ft.

event at two locations east of Scarboro Roadduring CY 2001. These locations are sampled aspart of CERCLA monitoring efforts in UnionValley. The results ranged between 57 and366 pCi/L; it is not certain what the reason is forthese results. Historical and subsequent results,which are consistently much lower in activity(below the drinking water standards), support theevaluation of these results as anomalous.

Exit Pathway and Perimeter Monitoring

Exit pathway groundwater monitoringactivities in the East Fork regime in CY 2001involved continued collection and trending of datafrom exit pathway monitoring stations. Datacollected to date indicate that volatile organiccompounds are the primary class of contaminantsthat are migrating through the exit pathways in theEast Fork regime. They are migrating predomin-antly at depths between 200 and 500 ft and appear



Fig. 6.22. Gross alpha activity in groundwater at the Y-12 Complex.

Fig. 6.23. Gross beta activity in groundwater at the Y-12 Complex.

to be restricted to the Maynardville Limestone, theprimary intermediate to deep groundwater exitpathway on the east end of Y-12. A verticalprofile of volatile organic compound contamina-tion is depicted in Fig. 6.21. The distribution ofvolatile organics is shown in Fig. 6.18. Their con-centrations are typically higher at depth because

most dilution and mixing with rainfall occur in theshallow portions of the Maynardville limestone. Inaddition, most of the volatile organic con-taminants at Y-12 are denser than water; there-fore, they tend to migrate downward within thesubsurface. The deep fractures and solutionchannels that constitute flow paths within the



Maynardville Limestone appear to be wellconnected. The characteristics of the flow pathscombined with the chemical characteristics of thecontaminants have resulted in migration forsubstantial distances off the ORR into UnionValley to the east of Y-12. The EnvironmentalMonitoring Plan specifies monitoring of threewells near the eastern ORR boundary for this exitpathway (Fig. 6.16).

In addition to the intermediate to deep path-ways within the Maynardville Limestone, shallowgroundwater within the water table interval in thevicinity of New Hope Pond, Lake Reality, andUpper East Fork Poplar Creek is also monitored.Historically, volatile organics have been observedin the vicinity of Lake Reality from wells, adewatering sump, and the Lake Reality Spillway.In this area, shallow groundwater flows north-northeast through the water table interval east ofNew Hope Pond and Lake Reality, following thepath of a diversion channel for Upper East ForkPoplar Creek.

During CY 2001, the observed concentrationsof volatile organics at the Lake Reality Spillwaycontinue to decrease. This decrease may bebecause the continued operation of a groundwaterplume-capture system in Well GW-845 (Fig. 6.21)south of the spillway may be reducing the levelsof volatile organics in the area. The installation ofthis system by BJC was completed in June 2000.This groundwater plume capture system willpump groundwater from the intermediate bedrockdepth to mitigate off-site migration of volatileorganics. The well continuously pumps ground-water from the Maynardville Limestone at about25 gallons per minute, passes the pumped waterthrough a water treatment system to remove thevolatile organics, and then discharges to UpperEast Fork Poplar Creek.

Monitoring wells near Well GW-845 haveshown some encouraging response to pumpingactivities. The multi-port system installed in WellGW-722 permits sampling of ten discrete zoneswithin the Maynardville Limestone between 87and 560 ft below ground surface. This well hasbeen instrumental in characterizing the verticalextent of the east-end plume of volatile organiccompounds and is critical in the evaluation of theeffectiveness of the plume capture system.Monitoring results from some sampled zones inWell GW-722 indicate possible reductions in

volatile organics due to groundwater pumpingupgradient at Well GW-845. Other wells, such asGW-605 and GW-382, also show dramaticdecreases that may be attributable to the plumecapture system operation. These indicators showthat operation of the plume capture system isdecreasing volatile organics upgradient and down-gradient of Well GW-845.

Three wells, located in the large gap in PineRidge through which Upper East Fork PoplarCreek exits Y-12, are used to monitor shallow,intermediate, and deep groundwater intervals.Shallow groundwater moves through this exitpathway, and very strong upward vertical flowgradients exist; two of the three wells located inthis area are artesian (water flows from the wellcasing due to unusually high naturally occurringwater pressure). Monitoring of these wells sinceabout 1990 has not shown that any contaminantsare moving via this exit pathway.

In CY 2001, five sampling locations weremonitored north and northwest of Y-12 toevaluate possible contaminant transport from theORR (Fig. 6.24). These locations are consideredunlikely groundwater or surface water contamin-ant exit pathways; however, monitoring wasperformed due to recent concerns regardingpotential health impacts from Y-12 operations tonearby residences. Two of the stations monitoredtributaries draining the north slope of Pine Ridgeon the ORR and discharged into the adjacentScarboro Community. One location monitors anupper reach of Mill Branch, which discharges intothe residential areas along Wiltshire Drive. Theremaining two locations monitor Gum HollowBranch as it discharges from the ORR and flowsnext to the Country Club Estates community.Samples were obtained and analyzed for metals,inorganics, volatile organics, and gross alpha andgross beta activities. There were no results thatexceeded a drinking water standard, nor werethere any indications that contaminants werebeing discharged from the ORR into thesecommunities.

6.10.3.2 Union Valley Monitoring

Groundwater monitoring data obtained in1993 provided the first strong indication thatvolatile organic compounds were beingtransported off the ORR through the deep



Fig. 6.24. Surface water sampling locations north of Pine Ridge (NPR), 2001. (GHK = Gum Hollow kilometer.)

Maynardville Limestone exit pathway. The UpperEast Fork Poplar Creek remedial investigation(DOE 1998) provided a discussion of the natureand extent of the volatile organics.

In CY 2001, monitoring of locations in UnionValley continued showing an overall decreasingtrend in the concentrations of contaminantsforming the groundwater contaminant plume inUnion Valley.

Under the terms of an interim record ofdecision, administrative controls, such as restric-tion on potential future groundwater use, havebeen established. Additionally, the previouslydiscussed plume capture system (Well GW-845)was installed and initiated to reduce volatileorganic compounds in Union Valley (DOE2002b).

6.10.3.3 Bear Creek HydrogeologicRegime

Located west of Y-12 in Bear Creek Valley,the Bear Creek regime is bounded to the north byPine Ridge and to the south by Chestnut Ridge.The regime encompasses the portion of BearCreek Valley extending from the west end of theY-12 Complex to Highway 95. Table 6.15describes each of the waste management siteswithin the Bear Creek regime.

Plume Delineation

The primary groundwater contaminants in theBear Creek regime are nitrate, trace metals,volatile organic compounds, and radionuclides.The S-3 Site is a source of all four of these conta-minants. The Oil Landfarm waste managementarea, consisting of the Oil Landfarm, the BoneYard/Burn Yard, the Hazardous ChemicalDisposal Area, and Landfill I, is a significantsource of uranium, other trace metals, and volatileorganics. Other sources of volatile organicsinclude the Rust Spoil Area, and the Bear CreekBurial Grounds waste management area. Densenonaqueous phase liquids (DNAPLs), heavier-than-water solvents that have a low watersolubility, exist at depths as great as or greaterthan 270 ft below the Bear Creek Burial Grounds.The DNAPLs consist primarily of volatileorganics such as tetrachloroethene, trichloro-ethene, 1,1-dichloroethene, 1,2-dichloroethene,and high concentrations of PCBs.

Contaminant plume boundaries are essentiallydefined in the bedrock formations that directlyunderlie many waste disposal areas in the BearCreek regime, particularly the Nolichucky Shale.The elongated shape of the contaminant plumes inthe Bear Creek regime is the result of preferentialtransport of the contaminants parallel to strike inboth the Knox Aquifer and the ORR Aquitards. A



Table 6.15. History of waste management units included in CY 2001 groundwater monitoring activities,Bear Creek Hydrogeologic Regimea


S-3 Site Four unlined surface impoundments constructed in 1951. Received liquid nitricacid/uranium-bearing wastes via the Nitric Acid Pipeline until 1983. Closed andcapped under RCRA in 1988. Infiltration was the primary release mechanism togroundwater

Oil Landfarm Operated from 1973 to 1982. Received waste oils and coolants tainted with metals andPCBs. Closed and capped under RCRA in 1989. Infiltration was the primary releasemechanism to groundwater. Part of the Oil Landfarm waste management area

Boneyard Used from 1943 to 1970. Unlined shallow trenches used to dispose of constructiondebris and to burn magnesium chips and wood. Part of the Oil Landfarm wastemanagement area

Burnyard Used from 1943 to 1968. Wastes, metal shavings, solvents, oils, and laboratorychemicals were burned in two unlined trenches. Part of the Oil Landfarm wastemanagement area

Hazardous ChemicalDisposal Area

Used from 1975 to 1981. Built over the burnyard. Handled compressed gas cylindersand reactive chemicals. Residues placed in a small, unlined pit. Part of the OilLandfarm waste management area

Sanitary Landfill I Used from 1968 to 1982. TDEC-permitted, nonhazardous industrial landfill. May be asource of certain contaminants to groundwater. Closed and capped under TDECrequirements in 1985. Part of the Oil Landfarm waste management area

Bear Creek BurialGrounds: A, C, andWalk-in Pits

A and C received waste oils, coolants, beryllium and uranium, various metallic wastes,and asbestos into unlined trenches and standpipes. Walk-in Pits received chemicalwastes, shock-sensitive reagents, and uranium saw fines. Activities ceased in 1981.Final closure certified for A (1989), C (1993), and the Walk-in Pits (1995). Infiltrationis the primary release mechanism to groundwater

Bear Creek BurialGrounds: B, D, E, J, andOil Retention Ponds 1and 2

Burial Grounds B, D, E, and J, unlined trenches, received depleted uranium metal andoxides and minor amounts of debris and inorganic salts. Ponds 1 and 2, built in 1971and 1972, respectively, captured waste oils seeping into two Bear Creek tributaries.The ponds were closed and capped under RCRA in 1989. Certification of closure andcapping of Burial Grounds B and part of C was granted 2/95

Rust Spoil Area Used from 1975 to 1983 for disposal of construction debris, but may have includedmaterials bearing solvents, asbestos, mercury, and uranium. Closed under RCRA in1984. Site is a source of volatile organic compounds to shallow groundwater accordingto CERCLA remedial investigation

Spoil Area I Used from 1980 to 1988 for disposal of construction debris and other stable, nonradwastes. Permitted under TDEC solid waste management regulations in 1986; closurebegan shortly thereafter. Soil contamination is of primary concern. CERCLA record ofdecision issued in 1996

SY-200 Yard Used from 1950 to 1986 for equipment and materials storage. No documented wastedisposal at the site occurred. Leaks, spills, and soil contamination are concerns.CERCLA record of decision issued in 1996

Above-Grade LLWStorage Facility

Constructed in 1993. Consists of six above-grade storage pads used to store inert,low-level radioactive debris and solid wastes packaged in steel containers

aAbbreviationsCERCLA = Comprehensive Environmental Response, Compensation, and Liability Act.LLW = low-level waste.PCB = polychlorinated biphenyl.RCRA = Resource Conservation and Recovery Act.TDEC = Tennessee Department of Environment and Conservation.



review of historical data suggests that contaminantconcentrations near source areas within the ORRAquitards have remained relatively constant since1986.

Nitrate

Unlike many groundwater contaminants,nitrate is highly soluble and moves easily withgroundwater. The limits of the nitrate plumeprobably define the maximum extent of sub-surface contamination in the Bear Creek regime.The horizontal extent of the nitrate plume isessentially defined in groundwater in the upper tointermediate part of the aquitard and aquifer [lessthan 300 ft (91 m) below the ground surface].

Data obtained during CY 2001 indicate thatnitrate concentrations in groundwater exceed thedrinking water standard in an area that extendswest from the S-3 Site for approximately 12,000 ft(3,660 m) down Bear Creek Valley (Fig. 6.17).Nitrate concentrations greater than 100 mg/Lpersist out to about 3000 ft (915 m) west of theS-3 Site, indicating no significant change fromprevious years. Historically, the highest nitrateconcentrations are observed adjacent to the S-3Site in groundwater in the unconsolidated zoneand at shallow depths [less than 100 ft (30.5 m)below ground surface] in the Nolichucky Shale.Furthermore, elevated concentrations of nitratehave been observed as deep as 740 ft (226 m)below ground surface. Surface water nitrateresults exceeding the drinking water standardduring CY 2001 were observed as far as 15,400 ft(4,694 m) west of the S-3 Site (Fig. 6.17).

Trace Metals

During CY 2001, uranium, barium, cadmium,chromium, lead, beryllium, and nickel have beenidentified from groundwater monitoring as thetrace metal contaminants in the Bear Creek regimethat exceeded the drinking water standards.Historically, elevated concentrations of thesemetals were observed at shallow depths near theS-3 Site. Disposal of acidic liquid wastes at thissite reduced the pH of the groundwater, whichallows the metals to remain in solution. Elsewherein the Bear Creek regime, where natural geo-chemical conditions prevail, these trace metalsmay occur sporadically and in close association

with source areas because conditions are typicallynot favorable for dissolution and migration. InCY 2001, these trace metals were evident atelevated concentrations within the surface waterand groundwater downgradient of the S-3 Site, theBear Creek Burial Ground, and the Oil Landfarmwaste management areas.

The most prevalent trace metal contaminantobserved within the Bear Creek regime isuranium, indicating that geochemical conditionsare favorable for its migration. The BoneYard/Burn Yard site has been identified as theprimary source of uranium contamination ofsurface water and groundwater. Uranium istypically observed at concentrations exceeding thedrinking water standard of 0.03 mg/L in shallowmonitoring wells, springs, and surface water loca-tions downgradient from all of the waste areas.Uranium concentrations above the drinking waterstandard were observed in surface water moni-toring stations over 3.8 miles (6.1 km) from BearCreek Burial Ground, the westernmost waste area.

Other trace metal contaminants that have beenobserved in the Bear Creek regime are boron,cobalt, copper, selenium, and strontium. Concen-trations of these metals have commonly exceededbackground and regulatory levels in groundwaternear contaminant source areas.


Volatile organic compounds are widespread ingroundwater in the Bear Creek regime (Fig. 6.18).The primary compounds are tetrachloroethene, tri-chloroethene, 1,2-dichloroethene, 1,1,1-trichloro-ethane, and 1,1-dichloroethane. In most areas,they are dissolved in the groundwater, and non-aqueous phase accumulations occur in bedrockmore than 250 ft (76 m) below the Bear CreekBurial Ground waste management area.

Groundwater in the aquitards that containsdetectable levels of volatile organic compoundsoccurs primarily within about 1000 ft (305 m) ofthe source areas. The highest concentrationsobserved in CY 2001 in the unconsolidated zonein the Bear Creek Regime occurred at the BearCreek Burial Ground waste management area inmonitoring Well GW-046, with a maximum totalresult of 6400 µg/L. The extent of the dissolvedplumes of volatile organic compounds is greater inthe underlying bedrock. The highest levels in the



Bear Creek regime occur in bedrock, just south ofthe Bear Creek Burial Ground waste managementarea. Historical levels have been as high as7,000,000 µg/L in groundwater near the sourcearea. Well GW-627, which is downgradient of theBear Creek Burial Ground waste managementarea, has continued to exhibit an increase involatile organic compound concentration(Fig. 6.25). The increasing trends observed inwells GW-082, GW-627, and GW-653 indicatethat some migration of volatile organics throughthe aquitards parallel to the valley axis and towardthe exit pathway (Maynardville Limestone) isoccurring in the unconsolidated and intermediatebedrock intervals.

Significant transport of volatile organics hasoccurred in the Maynardville Limestone. Dataobtained from exit pathway monitoring locationsshow that in the vicinity of the water table, anapparently continuous dissolved plume extendsfor about 12,000 ft (3660 m) westward from the S-3 Site to just west of the Bear Creek BurialGround waste management area. Typical concen-trations observed in CY 2001 in the MaynardvilleLimestone range from 220 µg/L in the central partof the regime (Well GW-225) to less than detect-able levels approximately 12,000 ft (3,660 m) tothe west of the S-3 site.

Radionuclides

The primary radionuclides identified in theBear Creek regime are isotopes of uranium and99Tc. Neptunium-237, 241Am, radium, strontium,and tritium are secondary and less widespreadradionuclides present in groundwater near the S-3Site.

Evaluations of the extent of these radio-nuclides in groundwater in the Bear Creek regimeduring CY 2001 were based primarily on measure-ments of gross alpha activity and gross betaactivity. If the annual average gross alpha activityin groundwater samples from a well exceeded15 pCi/L (the drinking water standard for grossalpha activity), then one (or more) of the alpha-emitting radionuclides (e.g., uranium) wasassumed present in the groundwater monitored bythe well. A similar rationale was used for annualaverage gross beta activity that exceeded50 pCi/L. More volatile radionuclides (i.e., 99Tc,3H) are qualitatively screened by gross beta

activity analysis and at certain monitoring loca-tions are evaluated isotopically.

Groundwater with elevated levels of grossalpha activity occurs near the S-3 Site and the OilLandfarm waste management areas (Fig. 6.22). Inthe bedrock interval, gross alpha activity exceeds15 pCi/L in groundwater in the Nolichucky Shaleonly near the S-3 Site. During CY 2001, noobserved gross alpha activity results from shallowor bedrock wells in the Bear Creek Burial Groundor in the Oil Landfarm waste management areaexceeded the drinking water standard. Dataobtained from exit pathway monitoring stationsshow that gross alpha activity in groundwater inthe Maynardville Limestone exceeds the drinkingwater standard for 12,000 ft (3660 m) west of theS-3 Site (e.g., GW-683). Gross alpha activitiesabove the drinking water standard in surface watersamples were observed about 4.5 miles (7.2 km)west of the S-3 Site.

The distribution of gross beta radioactivity ingroundwater in the unconsolidated zone is similarto that of gross alpha radioactivity (Fig. 6.23).During CY 2001, gross beta activity exceeded50 pCi/L within the water table interval in theMaynardville Limestone from south of the S-3Site to the Oil Landfarm waste management area.Within the intermediate bedrock interval in theMaynardville Limestone, the elevated gross betaactivity extends approximately 12,000 ft (3660 m)from the S-3 Site (Fig. 6.23) to exit pathwaypicket B (i.e., Well GW-706). Surface water grossbeta activities above the drinking water standardwere observed 16,000 ft (4877 m) west of the S-3Site. Technitium-99 activities mimic the grossbeta activity distribution across the Bear Creekregime.


Exit pathway monitoring began in 1990 toprovide data on the quality of groundwater andsurface water exiting the Bear Creek regime. TheMaynardville Limestone is the primary exit path-way for groundwater. Bear Creek, which flowsacross the Maynardville Limestone in much of theBear Creek regime, is the principal exit pathwayfor surface water. Various studies have shown thatsurface water in Bear Creek, springs along thevalley floor, and groundwater in the MaynardvilleLimestone are hydraulically connected. The



Fig. 6.25. Volatile organic compound concentrations in Bear Creek Burial Grounds Wells GW-627,GW-653, and GW-082.



western exit pathway well transect (Picket W)serves as the ORR perimeter well location for theBear Creek regime (Fig. 6.16).

Exit pathway monitoring consists of con-tinued monitoring at four well transects (pickets)and selected springs and surface water stations.Groundwater quality data obtained duringCY 2001 from the exit pathway monitoring wellsconfirmed previous data indicating that contamin-ated groundwater does not seem to occur muchbeyond the western side of the Bear Creek BurialGround waste management area (Fig. 6.26).However, levels of nitrate, gross alpha and grossbeta activities, and uranium exceeding theirrespective drinking water standards have beenobserved in surface water west of the burialgrounds (BWXT Y-12 2002).

Surface water and spring samples collectedduring CY 2001 indicate that spring dischargesand water in upper reaches of Bear Creek containmany of the compounds found in the groundwater.The concentrations in the creek and springdischarge decrease with distance downstream ofthe waste disposal sites (Fig. 6.27). A long-termslightly increasing gross alpha activity in BearCreek (BCK-09.40 and BCK-04.55) may indicatethat the Oil Landfarm waste management area isa significant contributor of alpha-emitting con-taminants (i.e., uranium) to surface water.

6.10.3.4 Chestnut Ridge Hydro-geologic Regime

The Chestnut Ridge Hydrogeologic Regime issouth of Y-12 and is flanked to the north by BearCreek Valley and to the south by Bethel ValleyRoad (Fig. 6.15). The regime encompasses theportion of Chestnut Ridge extending fromScarboro Road, east of Y-12, to Dunaway Branch,located just west of Industrial Landfill II.

The Chestnut Ridge Security Pits area is theonly documented source of groundwater conta-mination in the regime. Contamination from theSecurity Pits is distinct and is not mingled withplumes from other sources. Table 6.16 sum-marizes the operational history of waste manage-ment units in the regime.

Plume Delineation

The horizontal extent of the volatile organiccompound plume at the Chestnut Ridge SecurityPits is reasonably well defined in the water tableand shallow bedrock zones (Fig. 6.18). Ground-water quality data obtained during CY 2001indicates that the lateral extent of the plume ofvolatile organics at the site is similar to that whichoccurred in CY 2000, as evidenced by detectablesignature volatile organics in wells GW-609, GW-796, and GW-798. Concentrations of tetrachloro-ethene have been steadily decreasing in Well GW-609 since monitoring began in 1990 (Fig. 6.28).

Nitrate

Nitrate concentrations were well below thedrinking water standard of 10 mg/L at all moni-toring stations.

Trace Metals

Groundwater concentrations of trace metalsexceeded regulatory standards during CY 2001 atfour locations. Concentrations above the drinkingwater standard for nickel were observed insamples from three monitoring wells. One surfacewater monitoring station showed elevated concen-trations of arsenic.

Nickel concentrations above the drinkingwater standard were observed from a well at theIndustrial Landfill IV and from two wells at theUnited Nuclear Corporation site.

Elevated concentrations of nickel above thedrinking water standard were also detected in twowells at the United Nuclear site. The source ofnickel within wells at both the Landfill IV and theUnited Nuclear site is probably due to corrosionof well casings. This is further supported by thehigh concentrations of chromium seen in one ofthe wells at the United Nuclear site. Nickel andchromium are both primary components of stain-less steel, and the presence of both potentiallyindicates the occurrence of corrosion and sub-sequent dissolution of stainless-steel well casingand screen materials (Jones 1999).

Elevated concentrations of arsenic (above thedrinking water standard) were observed in onesurface water monitoring location downstreamfrom the Filled Coal Ash Pond, which is moni-



Fig. 6.26. Concentrations of selected contaminants in exit pathway monitoring Wells GW-724, GW-706,and GW-683 in the Bear Creek Hydrogeologic Regime.



Fig. 6.27. Concentrations of selected groundwater contaminants in Bear Creek.



Table 6.16. History of waste management units included in CY 2001 groundwater monitoring activities;Chestnut Ridge Hydrogeologic Regimea


Chestnut Ridge SedimentDisposal Basin

Operated from 1973 to 1989. Received soil and sediment from New Hope Pondand mercury-contaminated soils from the Y-12 Complex. Site was closed underRCRA in 1989. Not a documented source of groundwater contamination

Kerr Hollow Quarry Operated from 1940s to 1988. Used for the disposal of reactive materials,compressed gas cylinders, and various debris. RCRA closure (waste removal) wasconducted between 1990 and 1993. Certification of closure with some wastesremaining in place was approved by TDEC 2/95

Chestnut Ridge SecurityPits

Operated from 1973 to 1988. Series of trenches for disposal of classified materials,liquid wastes, thorium, uranium, heavy metals, and various debris. Closed underRCRA in 1989. Infiltration is the primary release mechanism to groundwater

United NuclearCorporation Site

Received about 29,000 drums of cement-fixed sludges and soils demolitionmaterials, and low-level radioactive contaminated soils. Closed in 1992; CERCLArecord of decision has been issued

Industrial Landfill II Central sanitary landfill for the Oak Ridge Reservation. Detection monitoring underpostclosure plan has been ongoing since 1996

Industrial Landfill V New facility completed and initiated operations 4/94. Baseline groundwatermonitoring began 5/93 and was completed 1/95. Currently under TDEC solid-waste-management detection monitoring

Industrial Landfill IV Permitted to receive only nonhazardous industrial solid wastes. Detectionmonitoring under TDEC solid-waste-management regulations has been ongoingsince 1988

Construction/DemolitionLandfill VI

New facility completed and initiated operations 12/93. Baseline groundwaterquality monitoring began 5/93 and was completed 12/93. Currently underpermit-required detection monitoring per TDEC

Construction/DemolitionLandfill VII

New facility; construction completed in 12/94. TDEC granted approval to operate1/95. Baseline groundwater quality monitoring began in 5/93 and was completed in1/95. Permit-required detection monitoring per TDEC was temporarily suspended10/97 pending closure of construction/demolition Landfill VI. Reopened and beganwaste disposal operations in 4/01.

Filled Coal Ash Pond Site received Y-12 Steam Plant coal ash slurries. A CERCLA record of decisionhas been issued. Remedial action complete

aAbbreviationsCERCLA = Comprehensive Environmental Response, Compensation, and Liability Act.RCRA = Resource Conservation and Recovery Act.TDEC = Tennessee Department of Environment and Conservation.

tored under a CERCLA record of decision (DOE2002b). A constructed wetlands is being utilizedto prevent surface water contamination by effluentfrom the Filled Coal Ash Pond. The locationwhere elevated arsenic levels were detected is up-gradient of this wetland area. Downgradient of thewetlands, concentrations are noticeably lower(below the drinking water for arsenic).


During CY 2001, the volatile organic com-pound concentrations observed in Well GW-305,located immediately to the southeast of LandfillIV, do not appear to be increasing as seen inprevious years (Fig. 6.29). Concentrations of thevolatile organic compounds in Well GW-305 haveremained below applicable drinking waterstandards.



Fig. 6.28. Tetrachloroethene concentrations in Chestnut Ridge Security Pits Well GW-609.

Fig. 6.29. Volatile organic compound concentrations in Industrial Landfill IV Well GW-305.

Efforts to delineate the extent of volatileorganic compounds in groundwater attributable tothe Security Pits have been in progress since1987. A review of historical data indicates thatconcentrations of volatile organics in groundwaterat the site have generally decreased since 1988. In

CY 2001, trace levels of volatile organics (lessthan the drinking water standard) continued to beobserved in downgradient monitoring WellGW-798, east of Industrial Landfill V. Thevolatile organics detected are characteristic of theSecurity Pits plume constituents. The presence of



volatile organics coupled with their generaldecrease at other wells indicates that the plume atthe Security Pits is receding but that somemigration through the karst dolostone to the south-east is occurring.

Radionuclides

In CY 2001, Gross alpha activities werebelow the drinking water standard of 15 pCi/L atall monitoring stations. Additionally, gross betaactivities were below the screening level of50 pCi/L. at all monitoring stations except atmonitoring Well GW-205 at the United Nuclearsite. This location has consistently exceeded50 pCi/L gross beta activity since August 1999(the last five samples). Isotopic analyses do notshow a correlative increase in the known beta-emitting contaminant of concern at the UnitedNuclear site (e.g., 90Sr).


Contaminant and groundwater flow paths inthe karst bedrock underlying the Chestnut Ridgeregime have not been well characterized by con-ventional monitoring techniques. Tracer studieshave been used in the past to attempt to identifyexit pathways. Based on the results of tracerstudies to date, no springs or surface streams thatrepresent discharge points for groundwater havebeen conclusively identified for water qualitymonitoring.

Monitoring of one large spring south ofIndustrial Landfill V and Construction/ Demoli-tion Landfill VII was continued in CY 2001 asrequired under the Environmental MonitoringPlan. Eight other springs and seven surface waterlocations within the Chestnut Ridge regime weresampled as part of overall exit pathwaymonitoring for the regime. No contaminants weredetected at these natural discharge points.

6. y-12 environmental monitoring programs · y-12 environmental monitoring programs 6-1 6. ......

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