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Pacific Gas and Electric,Company Environmental Services <br /> P.0.Box 7640 <br /> San Francisco,CA 94120 <br /> 4151973-7000 <br /> Direct Dial 4151973- T <br /> June 6, 1996 Telecopy 4151973-9201 <br /> James L. Tjosvold, P.E. <br /> Chief, Site Mitigation Branch <br /> California Environmental Protection Agency <br /> r Department of Toxic Substances Control <br /> 10151 Croydon Way, Suite 3 <br /> Sacramento, CA 95827 <br /> Attention: Mr. Fernando Amador <br /> Dear Mr. Tjosvold: <br /> Re: Docket #HSA 90/91-08 -Stockton Former Manufactured Gas Plant <br /> Site <br /> Subject: Results of Meeting on May 22, 1996 and Proposed Feasibility Study <br /> Approach <br /> This letter briefly summarizes the results of our meeting with the Department of <br /> Toxic Substances Control (DTSC) and the Central Valley Regional Water Quality <br /> Control Board (RWQCB) on May 22, 1996 and presents our proposed approach for <br /> developing a feasibility study for the Stockton former Manufactured Gas Plant <br /> (MGP) site. Also presented is a proposed schedule for submitting the feasibility <br /> study which includes monthly working sessions while the feasibility study is <br /> being developed. <br /> During our meeting, PG&E presented 1) proposed groundwater objectives and <br /> goals, 2) the conceptual model of how constituents migrated to groundwater in <br /> the past, 3) modeling results for evaluating current conditions and how long it <br /> takes for COPCs to migrate to groundwater, and 4) treatability study results for <br /> in-situ soil stabilization. The conceptual model was agreed on and further <br /> sensitivity analysis work was discussed with respect to the VLEACH model. The <br /> treatability study indicated mixed results for stabilization of the site source area <br /> soils. <br /> At the meeting, PG&E requested agreement on proposed objectives and goals for <br /> groundwater to help in the development of the final Soil Operable Unit Feasibility <br /> Study for the site. Soil remedial alternative selection is based on how effectively <br /> each alternative protects groundwater. Specific groundwater objectives and goals <br /> were not agreed to at the meeting. Instead, the agencies requested that the <br /> alternatives evaluated in the feasibility study (FS) address a range of groundwater <br /> goals. DTSC also suggested that PG&E consider combining the soil and <br />