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CaliforneRegional Water Quality &ntrol Board <br /> Central Valley Region <br /> Katherine Hart, Chair >, <br /> 11020 Sun Center Drive,#200, Rancho Cordova,California 95670-6114 <br /> Linda S.Adams (916)464-3291 • FAX(916)464-4645 Edmund G.Brown Jr. <br /> http://www.waterboards.ca.gov/centralvalley Governor <br /> Acting Secretary for <br /> Environmental Protection <br /> 21 January 2011 <br /> DESJC, M.BENSON <br /> Defense Distribution Depot San Joaquin <br /> P.O. Box 960001 <br /> Stockton, CA 95296 <br /> OFF-DEPOT PRIVATE WATER SUPPLY WELL CONTINGENCY PLAN <br /> DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN— TRACY SITE <br /> The California Regional Water Quality Control Board, Central Valley Region (Central Valley <br /> Water Board) staff has reviewed the October 2009 Draft Off-Depot Private Water Supply <br /> Well Contingency Plan (Draft Plan). URS Group, Inc., prepared the Draft Plan on behalf of <br /> the Defense Logistics Agency Enterprise Support San Joaquin, California (DLA). <br /> The goal of the Draft Plan is to protect the users of offsite private water supply wells <br /> located directly down-gradient of the DLA Tracy supply depot that may be in the flow path <br /> of groundwater plumes containing the following constituents of concern (CDCs): the <br /> volatile organic compounds (VOCs) trichloroethene, tetrachloroethene, and <br /> 1,1-dichloroethene, and the organochlorine pesticide dieldrin. The Draft Plan establishes <br /> Warning Levels for the COCs, identifies private water supply wells for monitoring, and <br /> proposes response actions that will be taken if Warning Levels are exceeded. <br /> Central Valley Water Board staff has prepared the comments in this letter to assist DLA <br /> with development of an acceptable Final Plan. We will only approve groundwater sampling <br /> frequency changes that are presented in Annual Monitoring Reports required by the <br /> Record of Decision (ROD) documents for the Tracy site. As you know, DLA's next <br /> opportunity for change request approvals is our review of the Draft Final Well Monitoring <br /> Program 2010 Annual Monitoring Report, 4Q09 — 3Q10. DLA has scheduled completion of <br /> the report after 18 February 2011 . <br /> Central Valley Water Board Staff Comments <br /> DLA's Draft Plan proposes to establish private well Warning Level concentrations. If the <br /> concentration of a COC exceeds its Warning Level, additional evaluation or monitoring <br /> would be implemented. However, DLA has not also proposed Levels that would trigger <br /> evaluation of alternative water supplies or that would trigger immediate water supply <br /> replacement. Furthermore, the schedule and actions for replacement of impacted private <br /> well water supply, such as supply of bottled water, wellhead treatment, well replacement, <br /> or alternative water supply hookup, is not provided in the contingency plan. <br /> California Environmental Protection Agency <br /> ed Recycled Paper <br />