SITE INFORMATION AND CORRESPONDENCE 1995-2004

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Pacific Gas and Electric. Company Environmental Services /:rpt/� P.O.Box 7640 r' Pdj San Francisco,CA 94120 Fts/l jq � Q/Tr/ 73- July 24, 1996 TelecopDirect0y1al 415 9/73-9201 9� J(il 29 4N 6.S4 James L. Tjosvold,P.E. Chief, Site Mitigation Branch California Department of Toxic Substances Control r 10151 Croydon Way, Suite 3 Sacramento, CA 95827 Attention: Mr. Fernando Amador Dear Mr. Tjosvold: Re: Docket#HSA 90/91/08 - Stockton Former Manufactured Gas Plant Site Subject: Quarterly Summary Report (Second Quarter. 19961 Pacific Gas and Electric Company(PG&E) submits this second quarter(1996) summary report for the Stockton Former Manufactured Gas Plant Site (site) in accordance with Provision 3.7 of the above-referenced order. This report summarizes technical activities conducted by PG&E in compliance with the order from April 1, 1996 to June 30, 1996 and activities planned for the next quarter. I. Activities Performed During Previous Quarter: The draft Soil Operable Unit Feasibility Study(OUFS), submitted to the agencies on November 7, 1995, had recommended that a treatability study be conducted to further evaluate the effectiveness of the proposed soil remedial action, in-situ shallow soil stabilization. Details of the treatability study were discussed with DTSC and the RWQCB in a series of conference calls from December 7, 1995 to January 25, 1996. During the conference calls, agreement was reached on the leaching procedure to be used to evaluate the effectiveness of in-situ shallow soil stabilization. The treatability study, which evaluated several potential soil stabilization mixtures,began in late January, 1996. Soil samples for the treatability study were collected from the site on January 25 and 26, 1996 and sent to the laboratory performing the treatability study. The final results of the treatability study(which was conducted in several phases)were available in early May, 1996. These treatability study results were discussed during a May 22, 1996 meeting between PG&E, DTSC and the RWQCB. Results of fate and transport modeling conducted by PG&E's consultant, C112M Hill, were summarized in a report titled "Evaluation of Potential Groundwater Impacts from Residues in Soil" which was submitted to DTSC and the RWQCB on March 13, 1996.