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Stbte of California • �rtment of Toxic Substances Control <br /> Memorandum <br /> To Date. August 14, 1992 <br /> Tracie Billington, P.E. , Acting Chief <br /> Federal Facility Unit <br /> From Department of Toxic Substances Control <br /> Site Mitigation Branch <br /> 855-7874 <br /> Sub]eckeview and Comment on the Draft Feasibility Study (FS) and <br /> Proposed Plan for Operable Unit No. 1, Defense Distribution <br /> Region West (DDRW) , Tracy <br /> The Department of Toxic Substances Control (Department) has <br /> reviewed the following reports: <br /> o "Draft Operable Unit No. 1 FS Report, DDRW - Tracy, <br /> -- - - California" prepared by Woodward Clyde Consultants, received <br /> on June 9, 1992 (hereinafter referred to as the FS) . <br /> o "Draft Proposed Plan for Contaminated Ground Water, Operable <br /> Unit No. 1, DDRW - Tracy, California" prepared by Woodward <br /> Clyde Consultants, received on June 9 , 1992 (hereinafter <br /> referred to as the Proposed Plan) . <br /> BACKGROUND <br /> DDRW Tracy has been in the midst of an RI/FS since 1980. It <br /> is a conclusion of their RI/FS that major health risks and <br /> impacts to the environment are from releases of hazardous wastes <br /> to the ground water. To respond to this threat and expedite <br /> remedial actions, Operable Unit No. 1. (OU # 1) has been <br /> established for ground water. <br /> OU # 1 is defined as the known ground water contamination at <br /> DDRW Tracy, both on and off-site. OU # 1 ' s boundaries are <br /> generally defined by the volatile organic compound (VOC) plumes. <br /> Tetrachloroethene (PCE) and trichloroethene (TCE) are the VOCs <br /> consistently detected via ground water monitoring. The vertical <br /> extent of OU # 1 is limited to the Upper Tulare geologic <br /> formation. Contamination has been detected down to 170 feet. <br /> The horizontal definition is not as precise, as there are several <br /> data gaps due to plume migration. It is projected that these <br /> data gaps can be filled through the quarterly monitoring program. <br /> The FS proposed remedial alternatives that would treat only <br /> s i <br />