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Mr. Robert Doss <br /> September 6, 1996 <br /> Page 2 <br /> 2 . The Agency' s comments concerning lack of <br /> recommendation' s to address contamination detected <br /> in Area II has not been addressed in your letter <br /> response. Instead the issue is deferred for <br /> discussion in our meeting on August 8, 1996 . DTSC <br /> understands the Phase IV workplan goals did not <br /> specifically include characterization of <br /> "additional" potential contaminant sources, <br /> nevertheless the overall investigation goals do. As <br /> stated and approved in the Remedial Investigation <br /> Report dated 8/93 , the objectives of the RI/FS/RAP <br /> are to: <br /> * Determine the nature and occurrence of <br /> hazardous substances . . . <br /> * Identify existing and potential migration <br /> pathways. <br /> * Determine the magnitude and probability of <br /> actual or potential harm. . . <br /> * Identify and evaluate appropriate response <br /> measures. . . <br /> Area II contamination was discovered during the <br /> phase IV workplan implementation activities, <br /> therefore, it would be appropriate to address the <br /> need for additional investigation work in the Phase <br /> IV report. The determination on data reeds would be <br /> based on the overall investigation goals listed <br /> above. <br /> 3 . The Agencies maintain that evidence exists to show <br /> that site groundwater gradients in Zone A have <br /> varied over time, likely resulting from local <br /> groundwater pumping over time. Summarized <br /> groundwater elevations reported in Table 4 of the <br /> July 1996 quarterly groundwater report show that <br /> zone A flow in the vicinity of MW-4 and MW-9 has <br /> varied from a western direction to a predominantly <br /> PA.1. <br /> 1 Adoee081o.vpd <br />