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CaliforniAegional Water Quality Conftl Board <br /> a <br /> Central Valley Region <br /> Linda S.AdamsKarl E.Longley,ScD,P.E.,Chair Arnold <br /> Secretaryfor Schwarzenegger <br /> Environmental -11020 Sun Center Drive#200,Rancho Cordova,California 95670-6114 Governor <br /> Protection Phone(916)464-3291 •FAX(916)4644645 <br /> http://www.watcrboards.ca.govkentralvalley <br /> 3 November 2008 <br /> DESJC, M.BENSON <br /> Defense Distribution Depot San Joaquin <br /> P.O. Box 960001 <br /> Stockton, CA 95296 <br /> DRAFT WAREHOUSE 10 INVESTIGATION REPORT, DEFENSE DISTRIBUTION DEPOT <br /> SAN JOAQUIN— TRACY, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Regional Water <br /> Board) staff has reviewed the September 2008 Draft Warehouse 10 Investigation Report <br /> (Draft Report). URS Group Inc. (URS) prepared the Draft Report on behalf of Defense <br /> Logistics Agency Enterprise Support San Joaquin, California (DESJC) for the Defense <br /> Distribution Depot Tracy Site (Depot),located in Tracy, California. <br /> Warehouse 10 is scheduled for demolition in 2009. In October and December 2007, the <br /> U.S. Army Corps of Engineers (USAGE) conducted a video survey of the industrial waste <br /> pipeline associated with the warehouse and collected soil samples. USACE used a direct- <br /> push drill rig to collect eight soil samples from beneath the warehouse for screening of <br /> potential risks to construction workers during the demolition work. Also, USACE conducted <br /> the sampling to develop management plans for handling of contaminated soil encountered <br /> during demolition activities. USACE prepared a draft report of findings in February 2008. <br /> In April and May 2008, URS collected soil, soil vapor, and groundwater samples at <br /> 29 locations beneath and adjacent to Warehouse 10. The Draft Report summarizes the <br /> USACE investigation results and presents the April-May 2008 sampling results. Based on <br /> the results, DESJC proposes to leave the contaminated soil in place, install an asphalt cap <br /> over the soil, and enact institutional controls. <br /> BACKGROUND <br /> Warehouse 10 formerly contained an aboveground solvent tank, a paint spray booth, and a <br /> floor drain (Attachment A). The floor drain was connected to industrial waste pipelines and <br /> sumps adjacent to the north and east sides of the warehouse. The tank or the pipelines <br /> leaked trichloroethene (TCE) to soil, soil vapor, and groundwater. The April 1998 Site-Wide <br /> Comprehensive Record of Decision (ROD) designated the solvent tank and associated floor <br /> drains as Solid Waste Management Unit (SWMU) 20. The ROD estimated that 320 cubic <br /> yards of SWMU 20 soil were contaminated by the following constituents of concern (CDCs): <br /> volatile organic compounds, semi-volatile organic compounds, pesticides, herbicides, and <br /> California Environmental Protection Agency <br /> Qd Recycled Paper <br />