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`- Californiategional Water Quality Cony Board twil '."llCentral Valley Region <br /> Linda S.Adams Arnold <br /> Karl E.Longley,SO,P.E.,Chair Schwarcenegger <br /> Secretaryfor <br /> EnvironmentalGovernor <br /> 11020 Sun Center Drive ri200,Rancho Cordova,California 95670-6114 <br /> Protection Phone(916)464-3291 •FAX(916)464-4645 <br /> http://www.watert)oards.ca.gov/�central'vva^all`ey <br /> U ECQ <br /> 12 August 2009 AU1' <br /> ENVIRL <br /> DESJC, M.BENSON PERS " <br /> Defense Distribution Depot San Joaquin <br /> P.O. Box 960001 <br /> Stockton, CA 95296 <br /> DRAFT FEASIBILITY STUDY, SOLID WASTE MANAGEMENT UNIT 20 <br /> DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN— TRACY, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley <br /> Water Board) staff has reviewed the June 2009 Draft Solid Waste Management Unit 20 <br /> Feasibility Study(Draft FS). URS Group Inc. prepared the Draft FS on behalf of Defense <br /> Logistics Agency Enterprise Support San Joaquin, California (DESJC) for the Defense <br /> Distribution Depot San Joaquin (DESJC) facility located in Tracy, California. <br /> The Draft FS evaluates seven alternative remedies for cleanup of soil contaminated primarily <br /> with TCE beneath Warehouse 10 at the Tracy facility. Historically, this building contained an <br /> aboveground solvent tank and associated piping and sumps, and a paint spray booth. The <br /> remedial investigations conducted in 1993 and 1995 designated the contamination from <br /> these structures as Solid Waste Management Unit 20 (SWMU 20). Also, a contaminated <br /> soil area adjacent to the east side of Warehouse 10 was included in SWMU 20. The remedy <br /> selected for SWMU 20 in the 1998 Site-Wide Comprehensive Record of Decision was <br /> excavation and off-site disposal, soil vapor extraction (SVE), and natural attenuation. <br /> However, after excavations were completed in 1997 and 1999 at the north side of <br /> Warehouse 10, it was suspected that additional contamination remained under the building, <br /> as well as the adjacent area to the east. SVE was not expected to be effective for the <br /> remaining contamination. The DDJC-Tracy 2004 Explanation of Significant Differences to <br /> the Site-wide Comprehensive Record of Decision (ESD) deleted SVE from the remedy for <br /> SWMU 20 and added institutional controls (ICs) for the remaining contamination. Also, the <br /> ESD stated that additional actions or continued ICs would be evaluated when Warehouse 10 <br /> is demolished. <br /> DDJC has scheduled Warehouse 10 for demolition this year. The purpose of the Draft FS is <br /> to comply with the requirements of the ESD. DESJC has selected the following remedy for <br /> SWMU 10: SVE enhanced with pneumatic fracturing. We understand that DESJC should be <br /> able to secure necessary funds to design, construct, and begin operation of the remedy in <br /> fiscal year 2010 if expedited approval of a Final FS is received. With removal of the building, <br /> SVE will again become a viable remedy for soil cleanup. The Central Valley Water Board <br /> concurs with the remedy and has no requirements for changes to the Draft FS. <br /> California Environmental Protection Agency <br /> �a Recycled Paper <br />