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lam♦ Q tl U Chevron kr1]{r1 Chevron 95:FF� -3 PH 30 Chevron USA Products Comping 8001:.Bollinger Canyon Rd:, Bldg. L January 30, 1995 P.O. Box 5004 San Ramon, CA 94583-0804 Site Assessment&•Remediation Group Ms. Mary Meays Phone(510)842-9500 San Joaquin County Environmental Health, P.O. Box A C Stockton, CA 95201 Re: Former Chevron Station#9-D18:45 East Harding Way 'Stockton CA i R Dear Ms. Meays: } In a letter, to your agency dated October 27, 1994, Chevron recommended-that no further remediation be performed at the subject site. Ina follow-up letter.dated December 1, 1994, your agency responded to Chevron's recommendation for no further remediation and established a deadline of January 31, 1995 for the submittal of a corrective action plan. Over the course of several telephone conversations it was leamed_that your agency would consider f` additional site-specific data in lieu of Chevron performing active remediation. Specifically,,if additional data demonstrated that residual hydrocarbons beneath the. subject site posed no immediate or potential threat to groundwater quality then, your agency would be willing to issue a statement indicating that no further remediation is required.'Therefore, instead of submitting a formal corrective action plan at this time;;I would like to present a description of the proposed actions which would be taken to demonstrate that.no threat to groundwater quality exists. ` A workplan will be submitted to your agency by February 28, 1995 which will describe the field 1 procedures, sampling protocol, and location of four confirmatory soil borings . The four borings will be located in all known and suspected hydrocarbon source areas. The collected soil samples will be analyzed for the presence of TPHG and BTEX constituents by EPA method's 8015 and 8020, respectively.The final boring and sample.locations will be subject to the approval of the San Joaquin County Public Health Services(SJCPHS).'The results-of BTEX-analyses will be used to better define the mass of hydrocarbons remaining and to provide input data to SESOILto model the transport of contaminants in the vadose zone. All SESOIL model input parameters will be pre- .. approved by SJCPHS. Similarly, the results of TPHG analyses will add definition to the mass of hydrocarbons remaining but, will also-be used to screen samplesfor additional leaching analyses by the Toxicity Characteristic Leaching Procedure (TCLP). - The soil analyses and modeling is being proposed to demonstrate that residual hydrocarbons in soil pose no present or potential threat to.:groundwater quality: If the results show that there is no source of groundwater contamination remaining; there'would .then be no need for active remediation and property development could proceed uninterrupted. Chevron would, continue monitoring groundwater to.vcrify .thai contaminants are contained and that there is no plume migrating. If you have any questions or comments, I can be reached at(510) 842-8695. fteryci�d f -