SITE INFORMATION AND CORRESPONDENCE

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TATE OF CALIFORNIA - Environmental Proted&gency PETE WILSON, Governor _ a CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION _. 3443 Routier Road, Suite A Sacramento, CA 95827-3098 PHONE: (916) 255-3000 FAX: (916) 255-3015 53 3 April 1995 Ms. Catherine Whitworth Trustee, Cal Farm Supply P.O. Box 280 Davis, CA 95617 SUMMARY OF MEETING, ADDITIONAL INFORMATION REQUIREMENTS Thank you for meeting with me last week to discuss the status of the former Cal Farm Supply facility on West Washington Street in Stockton. This letter summarizes our main points of discussion and should provide general information about the additional work that will be required at the site. In the past, staff from three different units within two different agencies have been overseeing the cleanup. In an effort to reduce duplication, I have talked to Diane Hinson of San Joaquin County Public Health, and Beth Thayer of the Regional Board. We have agreed that I will be the lead staff person working on this site, and will oversee both the pesticide and underground tank cleanups. An additional round of groundwater sampling should be completed this month. Because you are between consultants, Regional Board staff will collect the samples and submit them for analysis at our laboratory. The sampling is scheduled for April 17, 18, and if needed, April 19. Please contact me to make arrangements for staff to gain access to the site, for the guard dogs to be locked up, and for obtaining the keys to the monitoring wells. Last week, I gave you the telephone number for the State Water Resources Control Board's Petroleum UGT Cleanup Fund (916-227-4307). This fund reimburses qualified applicants for costs directly associated with assessment and/or remediation activities which exceed a total of $5,000 to $10,000 (depending on the responsible party's filing status). An application package for the Cleanup Fund is enclosed. You asked what the cleanup levels for the petroleum products in the groundwater would be. According to the Board's Underground Tank Unit, benzene needs to be cleaned up to less than 0.001 mg/1, and TPH-diesel to less than 0.1 mg/1. When these two target chemicals meet their respective cleanup levels, then the other petroleum products should also be below levels of concern. For the pesticides, each chemical should be cleaned up to less than its appropriate water quality criteria, as follows: dinoseb below 7.0 µg/1, MCPA below 11 µg/1, atrazine below 0.2 µg11, alpha- BHC below 0.01 µg/l, beta-BHC below 0.02 µg/l, and gamma-BHC below 0.03 µg/1. Once we have the results of the April 1995 sampling, we should have a good idea of the magnitude of the contamination. At this point, it appears that there are two separate pesticide plumes and one petroleum plume in the groundwater beneath the site. It is almost certain that the pesticides