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CalifornWegional Water Quality Cool Board <br /> �� .. <br /> Central Valley Region <br /> `\ Katherine Hart, Chair <br /> 11020 Sun Center Drive,#200,Rancho Cordova,California 95670-6114 <br /> (9 16)464-3291 •FAX(916)464-4645 I Eyrown dr. <br /> Matthew Rodriquez http;//www.waterboards.ca.gov/centralvalley E or <br /> Secretary for <br /> Environmental Protection f 1 C T 14 2011 <br /> ENVIRONMEWAL HEALTH <br /> 12 October 2011 PERMIT/SERVICES <br /> DESJC, M.BENSON <br /> Defense Distribution Depot San Joaquin <br /> P.O. Box 960001 <br /> Stockton, CA 95296 <br /> REVIEW OF DRAFT AREA 1/BUILDING 237 ENGINEERING EVALUATION/COST <br /> ANALYSIS, DEFENSE LOGISTICS AGENCY, DEFENSE DISTRIBUTION DEPOT <br /> SAN JOAQUIN— TRACY SITE <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br /> Board) staff has reviewed the Draft Area 1/Building 237 Engineering Evaluation/Cost Analysis <br /> (EE/CA), dated and received 19 September 2011. The EE/CA was prepared by <br /> HDR Environmental, Operations and Construction, Inc. on behalf of the Defense Logistics <br /> Agency (DLA) for the Defense Distribution Depot San Joaquin —Tracy Site depot. <br /> DLA believes that considerable reduction in risk to industrial workers exposed to pesticides in <br /> soil at Area 1/Building 237 (Site) of the Tracy depot can be accomplished by conducting a <br /> Non-Time-Critical Removal Action under the Comprehensive Environmental Response, <br /> Compensation, and Liability Act. The EE/CA presents a Streamlined Risk Evaluation using <br /> existing pesticide concentrations in soil data from the Site. The pesticides at the Site <br /> include 4,4-dichlorodiphenyldichloroethane, 4,4-dichlorodiphenyldichloroethylene, <br /> 4,4-dichlorodiphenyltrichloroethane, and dieldrin. In addition to the risk evaluation, the EE/CA <br /> presents the development and evaluation of remedial action alternatives for reduction of <br /> pesticide concentrations. The EE/CA-recommended alternative is to excavate contaminated <br /> soil with concentrations of pesticides estimated to be above a cumulative excess cancer risk to <br /> industrial workers of 1.11X10-5 and a health index of 2.67x10-2. <br /> Background <br /> In 2009, DLA installed vapor monitoring and extraction wells to enhance soil vapor extraction <br /> of TCE at the Site. Waste characterization analyses of soil cuttings from these wells detected <br /> pesticides at concentrations that exceeded hazardous disposal criteria. In October 2009, DLA <br /> hand augured soil borings and collected soil samples for chemical analyses from depths of <br /> 1, 3, and 5 feet below ground surface (bgs). At several locations, concentrations of pesticides <br /> were detected above screening levels in the 1-foot bgs sample. Concentrations generally <br /> decreased to below screening levels in the 3 and 5 foot bgs samples. In February and <br /> April 2011, DLA expanded the lateral and vertical characterization of pesticides in soil by <br /> drilling additional soil borings and collecting soil samples for chemical analyses of pesticides. <br /> In the EE/CA, DLA presents the results of these investigations, an evaluation of recently <br /> California Environmental Protection Agency <br /> Q*Recycled Paper <br />