SITE INFORMATION AND CORRESPONDENCE

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Background on the Ground Water and Soil Contamination Past Practices and Discovery of mary components of solvents and tion range of all contaminants Problem degreasers used at the LLNL site in detected at LLNL above State and LLNL is a research and develop- the past.They have been found in Federal standards,and the corre- ment facility owned'by the U.S. concentrations that exceed State sponding remediation standards for Department of Energy(DOE)and and Federal drinking water stan- ground water. operated by the University of Cali- dards. Fuel hydrocarbons(FHCs), forma.Initial release§of hazardous chromium,and lead are also found Activities to Date materials occurred in the mid-to in ground water at levels that LLNL has conducted a number of late-1940s when the site was oper- exceed regulatory standards. investigation and cleanup activities ated as an air training base by the In the unsaturated soil(i.e., since the ground water problem first U.S.Navy.Localized spills,leaking above the ground water),FHCs was discovered in 1983.Between tanks,surface impoundments,and have been found in one small area 1982 and 1984,hazardous waste was landfills contributed to subsequent and VOCs have been found in two excavated and removed from two contamination after the site was small areas in concentrations high areas in the eastern part of LLNL. transferred to DOE. enough to adversely affect ground Between 1984 and 1990,LLNL con- In 1983,LLNL discovered onsite water quality if the chemicals were ducted in-depth investigations to and offsite ground water contamina- allowed to naturally migrate down- characterize the nature and extent of tion originating from the LLNL site. ward to the water. the problem.LLNL also evaluated LLNL took immediate action to pro- the health risks posed by the site P See the box on page 3 for a discus- contaminants if no cleanup were to tect nearby residents using ground sion of the levels of tritium that have occur(see the summary of health water for drinking by providing bot- been found in the ground water and risks on page 3).In December 1990, tled water and then sealing off con- unsaturated soil.Table 1 shows the LLNL completed a study that evalu- taminated wells.LLNL also notified current pre-remediation Concentra- ated the feasibility of potential the regulatory agencies. continued on next page In July 1987,the U.S. EPA began overseeing LLNL's investigation and cleanup activities as art of the Concentration limit for drinking waters Preremedtation P P concentration Disc�arge Federal Superfund program.The range at LLNL limit for SU erfund program addresses past Federal M March 1996- treated P P $ P MCL MCL Martlt 1991 water releases of hazardous materials at Constituent (ppb) (ppb) (ppb) (ppb) private and public facilities nation- PCE 5 5 <0.1-1,0.56 4 wide.LLNL's cleanupprogram is TCE 5 5 <0. 0o 5 P $ 1(1-DCE 7 6 <0.55-37-370 5 funded by DOE.Other regulatory ci ,2-DCE 70 6 <0.5-24 5(total) agencies overseeing LLNL's trans-1,2-DCE 100 10 <6.5-t 5(total) a $ $ 1,1-DCA 5 <05-60 5 cleanup include the California 1,2-DCA 5 0.5 <0.1-190 5 Carbon tetrachloride 5 0.5 <0.1-91 5 Environmental Protection Agency, Total THMc 100" 100c <05-270 5 Department of Toxic Substances Benzene 5 1.0 <0.1.4fa 0.7 Toluene 1,000 <OS-4,200 5 Control(DTSC-formerly Depart- Xylenes(total) 10,000 1,750d <03-3,700 5 ment of Health Services,Toxic Sub- Ethyl benzene 700 680 m2�to 5 RW B; Ethye dibromide 0.05 0.02 <0.1-51 5 stances Control Program); QC Tofallenvocs — — up to 5,808 5 and the Alameda County Flood Chromium.3e 50(total) 5B(total) 9150(total) 50 Chro ium+6 a 50(total) 5o(total) <10-140 11 Control and Water Conservation Lead 15 50 <2-10 5A District(Zone 7). Tritiumg 20,000 pCilL 20,000 pCi/L <200-33,100 a Human receptor.The more striTent concentration limits on this pad of the table are shown in blue to illustrate Out What are the Contaminants? LLNL will comply with the a% stringentrequirements . b From NPDES Permit No.CA0029289(revised 9/1/90)and RWQCB Order No.911406.VOCsmific State discharge limitsexistin RWppCB Order No.90-106 only for PCE Hpyb and benzene(0.7 pyb).OtherVOCslistedinthis 6ble The ground water contaminants are included intMppb total VOClimit.Discharge lrmds�ormetals differsligfitlyaccording todischarge location. Of rima concern at LLNL are c Total trihalomethanes;includes chlomfomy bromoform,chlorodibromomethane,andbromodichlommethane(Ca0- P primary fomia Drinking Water Requirement). trichloroethylene(TCE) and per- dMCL is for either a single isomer or the sum of the active,costs.and para isomers. chloroethylene(PCE).These chem- f National Interim Primary Drinking Water Regulation for total chromium is 50 ppb. }' National Primary Drinking Water Regulation Enforceable Action Level(Federal Register,volume 56,number 110, icals are called volatile organic June 7,1991,p.26ab01. $ B Thorpe et at.(1990)show that ground water in the one well that currently exceeds the tritium MCL will be naturally compounds(VOCs)due to their h remediatedlong before itmigrates offsite. There is currently no NPDES discharge limit for tritium.LLNL will use the MCL for tritium as the discharge limit. tendency to evaporate readily into the air.These VOCs were the pri- Table 1. Remediation standards and state discharge limits for compounds of concern in ground water at the LLNL site.