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California &gional Water Quality Conj&l Board <br /> Central Valley Region <br /> Karl E. Longley,SeD,P.E.,Chair `mss" <br /> Linda S.Adams Arnold <br /> Secretaryfor Sacramento Main Office Schwarzenegger <br /> Environmental 11020 Sun Center Drive#200,Rancho Cordova,California 95670-6114 Governor <br /> Protection Phone(916)464-3291 •FAX(916)464-4645 <br /> http://www.waterboards.ca.gov/centralvailey <br /> 19 October 2007 <br /> DDJC-FA/Marshall Cloud <br /> Defense Distribution Depot San Joaquin <br /> P.O. Box 960001 <br /> Stockton, CA 95296 <br /> FOCUSED GROUNDWATER EXTRACTION TEST SUMMARY REPORT, SHARPE <br /> DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Regional Water <br /> Board) staff has reviewed the September 2007 DDJC-Sharpe Focused Groundwater <br /> Extraction Test Summary Report. The report was prepared by URS Group, Inc., on behalf of <br /> Defense Distribution Depot San Joaquin (DDJC) for work performed at the depot in Sharpe, <br /> San Joaquin County. <br /> As a component of the Operable Unit 1 Groundwater Response Action, the September 2005 <br /> Final DDJC-Sharpe Response Completion Plan specified the performance of focused <br /> groundwater extraction testing in two of the highest volatile organic compound concentration <br /> areas at the Sharpe site. Subsequently, URS Group, Inc., proposed focused extraction from <br /> monitoring wells MW418C and MW437C in the October 2005 Final DDJC-Sharpe Focused <br /> Groundwater Extraction test Work Plan. Historic concentrations of trichloroethene (TCE) in <br /> these two wells have been higher than other monitoring wells. Also, their concentrations <br /> have been higher than in nearby groundwater extraction wells EWC3 (near MW418C) and <br /> EECC1 (near MW437C). <br /> On 20 March 2006, groundwater extraction was stopped at EWC3 and started at MW418C. <br /> Likewise, extraction was stopped at EWCC1 and started at MW437C. This condition was <br /> maintained through 2 November 2006 at which time extraction was stopped at both <br /> monitoring wells. From 2 November 2006 through 8 March 2007, rebound monitoring was <br /> performed and groundwater was not extracted from any of the four wells. On 8 March 2007, <br /> extraction resumed from EWCC1. Extraction was to resume at EWCC1 during the third <br /> quarter of 2007. <br /> Before, during, and after the focused extraction period, water surface elevation, water <br /> sample quality, and system operating parameter data were collected from all four wells and <br /> other nearby monitoring wells. URS Group, Inc., summarized these data and recommended <br /> three measures to optimize the groundwater extraction system at the Sharpe site. The <br /> following text presents Regional Water Board staff comments on the measures. <br /> California Environmental Protection Agency <br /> C,p Recycled Payer <br />