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1 <br /> (\� Department of Toxic Substances Control <br /> Maziar Movassa hi <br /> Linda S.Adams Acting Director Arnold Schwarzenegger <br /> Environmental Protection <br /> Secretary for <br /> 8800 Cal Center Drive Governor <br /> Sacramento, California 95826-3200 ����� �J _ I_� <br /> JUN O 1 2009 <br /> ENVIRONMENT HEALTH <br /> May 29, 2009 PERMIT/SERVICES <br /> Mr. Maurice Benson <br /> Defense Logistics Agency <br /> Defense Distribution Depot San Joaquin, Sharpe Site <br /> P. 0. Box 960001 <br /> Stockton, California 95296-0250 <br /> CONCURRENCE ON THE MONITORING WELL INSTALLATION WORK PLAN FOR <br /> OFF-DEPOT WELL CLUSTERS MW536, MW537 AND MW538 FOR DEFENSE <br /> DISTRIBUTION DEPOT SAN JOAQUIN CALIFORNIA (DDJC), SHARPE SITE, <br /> LATHROP, CALIFORNIA <br /> Dear Mr. Benson: <br /> The Department of Toxic Substances Control (DTSC) received the above-mentioned <br /> work plan on April 9, 2009. The work plan describes the planned well installation <br /> activities on off-site areas to delineate and monitor volatile organic compounds (VOC) in <br /> groundwater as a result of recommendations made in the DDJC-Sharpe <br /> Comprehensive Cone Penetrometer Testing Investigation Results Report. The three <br /> proposed monitoring well (MW) clusters in all cases will provide an additional monitoring <br /> point for the offsite VOC plumes west of the South Balloon, Central Area and North <br /> Balloon. Specifically, the work plan proposes installation of the following MW clusters, <br /> including rationale: <br /> o MW536 Cluster - Southeast of PW047 <br /> • Guard well up-gradient from Potable Well (PW) PW047; <br /> • Monitor the potential migration of trichloroethene (TCE) plume <br /> originating from DDJC-Sharpe from C to C/D-zone groundwater; <br /> • Provide hydraulic data to provide better understanding of <br /> groundwater gradients to assist fate and transport model. <br /> e Printed on Recycled Paper <br />