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Department of Toxic Substances Control <br /> o <br /> Edwin F. Lowry, Director <br /> 8800 Cal Center Drive <br /> Winston H. Hickox Sacramento, California 95826-3200 Gray Davis <br /> Agency Secretary Governor <br /> California Environmental � <br /> Protection Agency u ll IEC EN E LTJ <br /> February 14, 2003 FEB 18 2003 <br /> ENVIR014MENT HEAi_TH <br /> PERMIT/SERVICLO <br /> Mr. Marshall Cloud <br /> Remedial Project Manager <br /> Defense Logistics Agency <br /> Defense Distribution San Joaquin California <br /> Building 100, Room 2, Ext. 4067 <br /> 25600 Chrisman Road <br /> Tracy, California 95376-5000 <br /> COMMENTS ON DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN CALIFORNIA <br /> (DDJC)-TRACY DRAFT SOIL VAPOR EXTRACTION OPTIMIZATION WORK PLAN <br /> DATED DECEMBER 13, 2002, TRACY SITE, TRACY, CALIFORNIA <br /> Dear Mr. Cloud: <br /> The Department of Toxic Substances Control (DTSC) has received the above- <br /> mentioned report on December 17, 2002. The work plan was prepared to recommend <br /> steps to optimize existing soil vapor extraction (SVE) systems and to devise an exit <br /> strategy for the SVE sites. DTSC has the following comments: <br /> General Comments <br /> 1.) Overall, the SVE system at DDJC-Tracy appears to be remediating the <br /> Volatile Organic Compounds (VOCs) effectively in the vadose zone because <br /> most of the post phase two sampling results are showing a 10-fold drop in <br /> contaminant concentrations over a period of less than eighteen months. <br /> 2.) Please discuss in the report how the current SVE results compare with the <br /> conceptual site model's predicted results by the VapourT program. <br /> Specifically, please discuss how the predicted migration of VOCs through <br /> dispersion and diffusion in the horizontal and vertical directions compares <br /> with the actual conditions. In addition, please discuss the estimated residual <br /> contaminant mass left in the vadose zone in each of the seven circuits and <br /> how that compares with the predicted modeling results. <br /> The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. <br /> For a list of simple ways you can reduce demand and cut your energy costs,see our Web-site at www.dtsc.ca.gov. <br /> 0 Printed on Recycled Paper <br />