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Department of Toxic Substances Control _ <br /> Maureen F. Gorsen, Director ". <br /> Linda S.Adams 8800 Cal Center Drive Arnold Schwarzenegger <br /> AgencyCal EPA Secretary <br /> Sacramento, California 95826-3200 Governor <br /> ECEWED <br /> April 24, 2007 MAY 02 <br /> 2007 <br /> ENVIRONM <br /> PERh1ITISFRVICEs 1 H <br /> Mr. Marshall Cloud <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 DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN (DDJC) <br /> TRACY SITE, HYPOTHETICAL RISK & HAZARD SCENARIO FOR DIELDRIN, <br /> TRACY, CALIFORNIA <br /> Dear Mr. Cloud: <br /> The Department of Toxic Substances Control (DTSC) received the above-mentioned <br /> document dated March 1, 2007. The letter report contained an e-mail, analytical data <br /> on dieldrin in ground water, and several tables summarizing risk calculations for <br /> residential exposure to ground water used for domestic purposes. DTSC's Human & <br /> Ecological Risk Division (HERD) has reviewed the documents and has the following <br /> comments: <br /> Comments <br /> 1. The risk assessment made by the Defense Logistics Agency (DLA) is incomplete <br /> because no analysis is presented using the maximum concentration of Dieldrin <br /> found in ground water as agreed to by all stakeholders and captured in an e-mail <br /> from Ms. Xuan-Mai Tran of the United Stated Environmental Protection Agency <br /> dated January 30, 2007. A risk analysis using the maximum concentration of <br /> dieldrin would have resulted in estimated cancer risk and non-cancer hazard <br /> index in excess of the "risk management range." Due to the present risk involved <br /> with dieldrin in ground water, dieldrin should remain a Contaminant of Concern <br /> (COC) for DDJC-Tracy. <br /> 2. The maximum concentration for dieldrin in ground water at DDJC-Tracy is <br /> presently 0.19 micrograms per litre (Ng/L), but DLA used 0.049 pg/L as their <br /> exposure point concentration. The exposure point concentration is also <br />