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California . ?gional Water Quality Cor ' )1 Board-4101 <br /> L. %, `""� Central Valley Region 'lowiII�W; , <br /> Karl E. Longley,ScD, P.E.,Chair <br /> Linda S.Adams Arnold <br /> 11020 Sun Center Drive 8200,Rancho Cordova,California 95670-6114 <br /> Secretary for Sehwarzenegger <br /> Environmental Phone(916)4aterbo 1 •FAX(916RECIEVIED <br /> Protectionhttp://wµ�n,.waterboards.ca.gov/ce Governor <br /> 25 January 2010 JAN 2 6 2010 <br /> ENVIRONNPENT 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 /> OFFSITE INVESTIGATION LETTER REPORT, PG&E FRENCH CAMP GENERAL <br /> CONSTRUCTION YARD, FRENCH CAMP, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br /> Board) staff reviewed the 17 December 2009 Offsite Investigation Report (Report) submitted <br /> by Stantec Consulting Corporation (Stantec) on behalf of Pacific Gas & Electric Company <br /> (PG&E) for the general construction yard at 401 East French Camp Road in French Camp <br /> (Site). <br /> PG&E has used the Site since the late 1950s as a general construction yard and purchased <br /> the property in 1991. In June 2005, PG&E performed a Phase I environmental site <br /> assessment, which found that in 1995, PG&E removed one concrete ConVault-style <br /> aboveground tank (AGT). The ConVault tank had replaced older steel AGTs and consisted of <br /> separate vessels for storing diesel and gasoline. The French Camp Fire Department oversaw <br /> the 1995 removal of the ConVault AGT. It is unknown when the steel AGTs were removed. <br /> In July and August 2009, PG&E collected soil samples at the Site and a water sample from the <br /> nearby domestic well at 393 East French Camp (Gillit Property). The soil boring about two <br /> feet from the property boundary between the Site and Gillit property contained petroleum <br /> hydrocarbons. The domestic well did not contain any petroleum hydrocarbons. <br /> On 22 October 2009, PG&E drilled five soil borings on the Gillit Property to a depth of 20 feet <br /> below ground surface (bgs) and analyzed soil samples for petroleum hydrocarbons. The <br /> 14-foot bgs sample from boring SB-14 contained the maximum concentrations of total <br /> petroleum hydrocarbons as diesel (TPHd) and naphthalene at 202 milligrams per kilogram <br /> (mg/kg) and 5.7 mg/kg, respectively. The 20-foot bgs sample from the same boring did not <br /> contain petroleum hydrocarbons above laboratory detection limits. Three of the soil borings <br /> were converted to soil vapor probes, and PG&E collected soil vapor samples at five and <br /> 12 feet bgs. None of the soil vapor samples exceeded the California Regional Water Quality <br /> Control Board — San Francisco Bay Region Environmental Screening Levels (ESLs). <br /> Our comments are included below- <br /> 1. <br /> elow:1. Central Valley Water Board staff concurs with PG&E's recommendation not to excavate <br /> the contaminated soil on the Gillit Property. The soil concentrations are below the <br /> ESLs for gross contamination in deep soil (greater than 10 feet bgs) and are below <br /> California Environinental Protection Agency <br /> pra Recycled Paper <br />