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STATE OF CALIFORNIA-EmAronmental Protectilmency PETE WILSON, Governor CALIFORNIA REGIONAL WATER QUALITY CgfiffOL BOARQr�Ea�rH CENTRAL VALLEY REGION f tiiCE �� 3443 Routier Road,Suite ASacramento,CA ' PHONE:916)55-3000098 96 CrT _p PM 11 18 FAX:(916)255-3015 �J , 4 October 1996 Ms. Julie Raining Georgia Pacific Corporation P.O. Box 105605 Atlanta, GA 30348-5605 GROUND WATER REMEDIATION AT GEORIA-PACIFIC CORPORATION, TRACY, SAN JOAQUIN COUNTY Thank you for meeting with us on 18 September 1996 to discuss the status of ground water remediation at Georgia-Pacific's (GP) former facility in Tracy. As discussed at the meeting, I have reviewed the files. The attached memo summarizes the history of operations at the facility, the ground water investigation and remediation, and the Board's involvement with the site since 1984. The major issue at our meeting was the cleanup goal for chloroform. As we stated, the 100µg/1 maximum contaminant level (MCL)for chloroform is not appropriate as a cleanup goal for chloroform in ground water. Chloroform is a probable human carcinogen with a one-in-a-million cancer risk estimate ranging from 0.26 µg/1 (National Academy of Sciences) to 6 /..4g/1 (USEPA Integrated Risk Information System). The MCL for total THMs was based mainly on technologic and economic considerations associated with converting a water supply treatment system to some other disinfection methods. Such a cost/benefit balancing is not germane for protection of a source of drinking water which has not been chlorinated. The enclosed memo reviews the cleanup goals that have been used for the GP site. In 1985, the Board established a cleanup goal of 0.2 µg/1 chloroform for the GP site. In December 1991, staff updated the cleanup goal to 5 µg/1. As we discussed at the meeting, the ground water extraction and treatment system was shut down in 1991 and had not achieved the Board's cleanup goal for chloroform. While the system significantly reduced chloroform levels in the source area, the cleanup goal of 5 µg/1 chloroform was not achieved and the extraction system did not contain the full extent of the plume. Chloroform levels in the source area and at the monitoring well farthest downgradient are still greater than the cleanup goal.