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ATTACHMENT <br /> EPA COMMENTS ON THE <br /> DRAFT WORK PLAN AMENDMENTS (12 FEB 93) FOR PHASE I OF THE <br /> COMPREHENSIVE REMEDIAL INVESTIGATION/FEASIBILITY STUDIES (RI/FS) AT <br /> DEFENSE DISTRIBUTION REGION WEST (DDRW) <br /> TRACY, CALIFORNIA <br /> Comments are subdivided into four major sections following the major sections of <br /> the Work Plan Amendments. <br /> FIELD SAMPLING APPROACH <br /> I. DDRW-Tracy and EPA have discussed at past project manager meetings the need to <br /> address possible contamination in the confined aquifer (or the rationale to support a <br /> decision to not investigate the confined aquifer, as appropriate). Should DDRW- <br /> Tracy conclude that existing data support a decision to not investigate the confined <br /> aquifer, this decision needs to be substantiated in the Work Plan Amendment. <br /> 2. The data collected during excavations for the Subsistence Warehouse in August 1991 <br /> have not been adequately summarized. Fifty-five drums containing unknown <br /> substances were discovered when excavating for this warehouse. Soil samples from <br /> within each drum, as well as soil samples from beneath the drums, were taken and <br /> analyzed for various constituents. Contaminants detected in the soil samples <br /> included dioxins, pesticides, metals, some volatile organic compounds (VOCs), and <br /> semivolatiles. EPA has previously commented upon this issue; this important <br /> information on contamination, and any relevant conclusions, belongs in the <br /> Comprehensive Work Plan. <br /> • Please provide a quantitative summary of all pertinent data related to this <br /> solid waste management unit (SWMU) No. 13, including the Telic report, in <br /> the updated work plan. <br /> 3. The Defense Logistics Agency (DLA), during the DDRW-Tracy Project Managers' <br /> Meeting of June 15-16, 1992, agreed to sample the old drainage ditch to the <br /> northwest of the present Storm Pond. Two surface and near-surface samples were to <br /> be taken and analyzed for all analytes as at SWMU No. 4 (the Storm Pond). This <br /> sampling should be in the work plan amendments. <br /> • Please add this item to the work plan. <br /> 4. EPA has noted ambiguities in the Comprehensive Work Plan with regard to the <br /> stated objectives for Phase I sampling. At the project manager meeting of March 23, <br /> USEPA/R9 12 Apr 93 1/19 <br /> 1 <br />