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5 FATE OF CALIFORNIA <br /> PETE WILSON. Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— Z,. <br /> CENTRAL VALLEY REGION <br /> 3443 ROUTIER ROAD, SUITE A <br /> SACRAMENTO, CA 95827-3098 <br /> PHONE: (916) 361-5600 <br /> FAX: (916) 361-5686 <br /> 22 November 1991 <br /> Mr. Abel Haines <br /> Director, Environmental Program Office <br /> Defense Distribution Region West, Tracy <br /> Tracy9066o <br /> 7_rno <br /> .racy, C <br /> V , JJ / JV <br /> OFF-SITE SAMPLING OF DOMESTIC SUPPLY WELLS AND INTERIM WATER SUPPLY, DEFENSE <br /> DISTRIBUTION REGION WEST (DDRW), TRACY, SAN JOAQUIN COUNTY <br /> On 6 and 14 November 1991, the Board with the Department of Toxic Substances <br /> Control (DTSC) , collected ground water samples from the domestic supply wells at <br /> 25516 (Rose residence) and 25080 (Robertson residence) South Banta Road. The <br /> ground water samples were analyzed for volatile organic constituents by the <br /> Board's laboratory. The results revealed that carbon tetrachloride was present <br /> in both wells in concentrations exceeding the California Primary Maximum <br /> Contaminant Level (MCL) and that trichloroethylene (TICE) was present in the <br /> samples collected at the Rose residence. <br /> We understand that DDRW, Tracy has supplied bottled water to the Rose residence. <br /> We have also been informed that DDRW, Tracy has not supplied bottled water to the <br /> Robertson residence because it believes that the site is not the source of the <br /> carbon tetrachloride ground water contamination. <br /> We concur with the DTSC that it is premature for DDRW, Tracy to conclude that it <br /> is not the source of the carbon tetrachloride contamination. The site-wide <br /> Remedial Investigation (RI) must be completed in order to determine whether <br /> uninvestigated on-site waste management units may be sources of carbon <br /> tetrachloride, or other volatile organic constituent (VOC) , ground water <br /> contamination. The enclosed memorandum discusses our position on this issue in <br /> more detail . <br /> We request that DDRW, Tracy supply the bottled water to the Robertson, as well <br /> as the Rose residence, until it is conclusively shown that DDRW, Tracy is not the <br /> source of the carbon tetrachloride contamination. The supply of bottled water <br /> is an interim measure. We concur with San Joaquin County that this supply should <br /> continue until a long term alternative water supply can be implemented. <br /> Therefore, we request that DDRW, Tracy submit by 15 January 1992 a time schedule <br /> for development of a long term alternative water supply for those domestic wells <br /> impacted by VOC ground water contamination emanating from the site. Ultimately, <br /> DDRW, Tracy, with further verification sampling, will need to install additional <br /> monitor wells to define the lateral and vertical extent of the VOC plume. <br />