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MS <br /> Californigegional Water Quality Cot�pl Board <br /> Central Valley Region <br /> Karl E.Longley,ScD,P.E.,Chair -- <br /> Linda S.Adams Arnold <br /> Secreta f or Sacramento Main Office <br /> 11020 Sun Center Drive#200,Rancho Cordova,California 95670-6114 Schwovernegger <br /> Environmental <br /> Protection Phone(916)464-3291 •FARC(916)464-4645 Governor <br /> http:/h+,Au.waterboards,ca.gov/centTalvalley <br /> 21 December 2007 DEC 2 6 2007 <br /> ENVIRONMENT HEALTH <br /> PERMIT/SERVICES <br /> Ms. Anne Conner <br /> Pacific Gas and Electric Company <br /> 375 N. Wiget Lane <br /> Walnut Creek, CA 94598 <br /> FOURTH QUARTER 2007 GROUNDWATER MONITORING REPORT, PG&E FRENCH <br /> CAMP GENERAL CONSTRUCTION YARD, FRENCH CAMP, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board — Central Valley Region (Regional Water <br /> Board) staff reviewed the 13 December 2007 Fourth Quarter 2007 Groundwater Monitoring <br /> Report (Report) submitted by SECOR International, Inc. (SECOR). SECOR submitted the <br /> Report on behalf of Pacific Gas & Electric Company (PG&E) for the general construction yard <br /> at 401 East French Camp Road in French Camp (Site). <br /> PG&E has used the Site since the late 1950s as a general construction yard, and in 1991 <br /> PG&E purchased the Site. In June 2005, PG&E performed a Phase 1 environmental site <br /> assessment (Phase 1 Report), which stated that in 1995, PG&E removed one concrete <br /> ConVault-style aboveground tank (AGT). The Phase 1 Report also stated that the ConVault <br /> had replaced older steel AGTs. <br /> In 2005 and 2006, PG&E completed two separate soil investigations near the former ConVault <br /> and steel AGT locations. Soil samples contained elevated levels of petroleum hydrocarbons. <br /> In February 2007, PG&E excavated about 40 cubic yards of petroleum contaminated soil. In <br /> April 2007, PG&E conducted an additional investigation, and in May 2007 installed three <br /> monitoring wells. <br /> On 13 November 2007, PG&E conducted the fourth quarter 2007 monitoring event. <br /> Groundwater flow was toward the north-northwest, whereas in May 2007, the groundwater <br /> flow direction was to the southeast. Petroleum hydrocarbons were not detected in any of the <br /> monitoring wells. <br /> The Report shows that PG&E used a silica gel cleanup procedure during analysis of total <br /> petroleum hydrocarbons as diesel (TPHd) and TPH as motor oil (TPHmo). Regional Water <br /> Board staff do not allow the use of silica gel cleanup before analysis. Silica gel cleanup is a <br /> tool that is used to separate polar organics from normally non-polar petroleum hydrocarbons in <br /> water samples, but silica gel can also filter out non-polar petroleum hydrocarbons. In addition, <br /> the polar organics may be early breakdown products of petroleum hydrocarbons and should <br /> not be ignored. PG&E may not use the silica gel cleanup for future sampling events. <br /> California Environmental Protection Agency <br /> �a� Recycled Paper <br />