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Department of Toxic Substances Control <br /> Maziar Movassaghi <br /> Linda S.Adams Acting Director Arnold Schwarzenegger <br /> Secretary for 8800 Cal Center Drive Governor <br /> Environmental Protection Sacramento, California 95826-3#WEGEE E0 <br /> J 1 2010 <br /> February 26, 2010 ENVINUNMENT HEALTH <br /> Mr. Maurice Benson PERMIT/SERVICES <br /> Remedial Project Manager <br /> Defense Distribution Depot—Tracy Site <br /> P.O. Box 960001 <br /> Stockton, California 95296-0320 <br /> COMMENTS ON THE DRAFT OFF-DEPOT PRIVATE WATER SUPPLY WELL <br /> CONTINGENCY PLAN FOR DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN <br /> CALIFORNIA (DDJC), TRACY SITE, TRACY, CALIFORNIA <br /> Dear Mr. Benson: <br /> The Department of Toxic Substances Control (DTSC) received the above-mentioned <br /> report on October 21, 2009, submitted by the URS Corporation on behalf of Defense <br /> Enterprises Support San Joaquin California (DESJC). DTSC did not provide comments <br /> initially due to staffs leave and the belief that the Contingency Plan's findings would be <br /> summarized and provided in the DDJC-Tracy Annual Monitoring Report. Unfortunately, <br /> the DDJC-Tracy 2009 Annual Monitoring Report, a primary document, did not include <br /> the Contingency Plan decision logic and rationale, thus prompting DTSC to provide <br /> comments on the Tracy Private Water Supply Well Contingency Plan. <br /> The report provides the framework for establishing response actions if contaminants of <br /> concern (COCs) originating from DDJC-Sharpe are impacting or could potentially <br /> impact down-gradient potable water supply wells (PWs) used by human receptors. <br /> Specifically, the Contingency Plan identifies three wells that fit into two categories: <br /> affected wells, and wells potentially in the flow path of contaminant plumes originating <br /> from DDJC-Tracy. The Plan establishes warning levels, equivalent to the Record of <br /> Decision's Aquifer Cleanup Level (ACL) for the contaminants of concern (CDCs) <br /> detected in these potable wells. If the COC warning level is exceeded in any of the <br /> PWs sampled, then a more aggressive sampling approach is adopted, including 30-day <br /> repeat sampling, quarterly sampling for one year, and a new response action adopted <br /> which may include continued quarterly sampling, adding wellhead treatment, or <br /> providing bottled water. <br /> ® Printed on Recycled Paper <br />