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0 RECEIVED <br /> ` <br /> .........e <br /> FEB 2 2 2013 <br /> FNVIF()NA/.Fl<i P11n FF(:11:) <br /> Water Boards <br /> Central Valley Regional WaterJjJJkRYol Board <br /> Michael N. Oliphant 15 February 2013 <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> P. O. Box 6012 <br /> San Ramon, CA 94583 <br /> REVIEW-ADDITIONAL SOILS INVESTIGATION REPORT, 990 BEECHNUT AVENUE, TRACY, <br /> SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted an Additional Soil Investigation <br /> Report (Report) dated 25 September 2012, for the 990 Beechnut Avenue project (Site) in central <br /> Tracy. The Report was prepared on behalf of Chevron by AMEC Environment & Infrastructure, Inc. <br /> (AMSC). <br /> Based on the findings of a December 2010 Excavation Completion and Updated Screening Level <br /> Risk Assessment (SLRA) Report, 4,024 tons of polynuclear aromatic hydrocarbon (PAH) affected <br /> �11-nil n was mloved frn the Ci+Q AME C' then1 I^-ateA +he SLRA using the findings of a 2008 risk <br /> assessment. Accord ng to the 2010 SLRA findings, the Site was suitable for future <br /> commercial/industrial uses, with the exception of two other areas on the Site, where ethylbenzene <br /> and total petroleum hydrocarbon as crude oil (TPHc) remained in shallow soil. Chevron decided to <br /> conduct additional characterization to support possible closure with unrestricted use, for either a <br /> future commercial/industrial and/or residential use scenario. Central Valley Regional Water Quality <br /> Control Board staff approved a workplan for the additional work in correspondence dated 13 March <br /> 2012. The final AMEC Report concluded the Site characterization is complete, and the prior risk <br /> assessment can be updated and a revised SLRA submitted. <br /> Central Valley Water Board staff concur that the Site has been characterized and the risk <br /> assessment can be updated using the new information. By 30 September 2013, please provide the <br /> revised/updated risk assessment for the Site considering the likely future Site use risk exposure <br /> scenario(s). <br /> If you have any questions or comments, please contact Dean Hubbard at (559) 445-5179 or by email <br /> at dh,ubbard waterboards.ca. ov. <br /> S LTON R. GRAY <br /> Senior Engineering Geologist <br /> cc: San Joaquin County DEH, Stockton <br /> Mari Gilmore, AMEC, Oakland <br /> Caryn Kelley, AMEC, Rancho Cordova <br /> KAR_ E. '—ONOLEy SCD, P.E.. CHAIR. I PAMELA C. CREEDON P.E.. BCEE, ExecunvE OFFICER <br /> 1685 E Street,Fresno, CA 93706 www.waterooartls Ca-gov/Centralvalley <br />