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f <br /> 0 <br /> Department of Toxic Substances Control <br /> Maureen F. Gorsen, Director <br /> Linda S.Adams 8800 Cal Center Drive Arnold Schwarzene er <br /> Secretary for 99 <br /> GovernorSacramento, California 95826-3200 IENED Governor <br /> Environmental Protection D RRC <br /> MAR 1 6 2009 <br /> March 12, 2009 ENVIRONMENTfEALTH <br /> QF4An7/cCglnrre <br /> Mr. Maurice Benson <br /> Defense Logistics Agency <br /> Defense Distribution Depot San Joaquin, Tracy Site <br /> Post Office Box 960001 <br /> Stockton, California 95296-0250 <br /> COMMENTS ON THE NORTHWESTERN CORNER DIELDRIN PLUME FEASIBILITY <br /> STUDY REPORT FOR DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN <br /> CALIFORNIA (DDJC) —TRACY, TRACY, CALIFORNIA <br /> Dear Mr. Benson: <br /> The Department of Toxic Substances Control (DTSC) received notice the <br /> above-mentioned study was available for regulatory review on November 21, 2008. <br /> The goal of the feasibility study was to determine whether the assumed remedy for OU1 <br /> groundwater contamination, pump and treat, would be technically and economically <br /> feasible to remove dieldrin mass from groundwater in the northwestern corner of DDJC- <br /> Tracy, including offsite plume. <br /> Background: <br /> Dieldrin entered the groundwater in the NWC area through the periodic operation of <br /> injection wells (IWs) IW001, IW002, and IW003 between 1992 and 1995. The injection <br /> wells were installed in late 1990 and early 1991 as part of the original pump-and-treat <br /> Interim Remedial Measure for groundwater contaminated with volatile organic <br /> compounds at DDJC-Tracy. 14 <br /> DTSC has reviewed the report and has the following comments: <br /> Comments: <br /> 1. Mass removal Test Area #1 occurred from September 9th through October 9th <br /> with Test Area #2 spanning September 12th through October 13th, 2008. During <br /> these operational periods both extraction wells (EW) EW056A and EW055B were <br /> 0 Printed on Recycled Paper <br />