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ATTACHMENT I <br /> REMEDIAL INVESTIGATION <br /> EPA COMMENTS ON <br /> DDRW-TRACY'S <br /> DRAFT LETTER REPORT OF 10/30/91 <br /> GENERAL COMMENT <br /> Response Nos. 2, 4, and 5 <br /> Adequate, provided EPA's Comments on DDRW-Tracy' s Draft Solid <br /> Waste Management Unit (SWMU) Engineering Report are properly <br /> addressed in the Comprehensive Site-Wide Remedial <br /> Investigation/Feasibility Study (RI/FS) , along with the pertinent <br /> EPA Comments on the Draft RI Report. This should include the <br /> selection of, say, a 10-foot by 10-foot grid with random sampling <br /> both horizontally and vertically. Statistical criteria for <br /> number of samples should be estimated, at a minimum. Clear and <br /> defensible rationale must be provided for selection of sampling <br /> locations. <br /> SPECIFIC COMMENTS <br /> Response No. 5 <br /> DDRW-Tracy must discuss how the degreasing components <br /> trichloroethene (TCE) and tetrachloroethene (PCE) are currently <br /> stored at the site. State what information source or sources was <br /> used in making this conclusion. Sources of information (e.g. , <br /> inventory records, manifests, aerial photographs or personnel <br /> interviews) and supporting analytical data are necessary to <br /> support these statements. <br /> Response No. 6 <br /> According to the Installation Assessment (IAS) of Defense Depot <br /> Tracy, "Before the IWPs were dug, one in 1972 and the other in <br /> 1979, most of the industrial wastes were drummed and disposed of <br /> by a contractor off-post. Some `may have gone into the sanitary <br /> or storm system. ' Before the second IWP was dug, there was `a <br /> small overflow to the sewage effluent pond' from the original <br /> IWP. " (Page 32) These statements from the IAS support EPA' s <br /> contention that the sanitary settling ponds (and also the storm <br /> pond) may have received at least some industrial wastes. <br /> Response No. 10 <br /> Perhaps the last sentence should read "Metals that may impact the <br /> risk assessment of the groundwater plume will be addressed in the <br /> I-1 <br />