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DETAILED COMMENTS <br /> 9. Paragraph 1.1.0.0.1, 'Purpose", Page 1-1 <br /> The purpose of the Comprehensive RDFS, as stated in this paragraph, is "to investigate <br /> potential sources of environmental contamination at the DDRW-Tracy." No mention <br /> is made in this paragraph that the purpose of the Comprehensive RI/FS includes <br /> collection of data to support the feasibility study, the baseline risk assessment or the <br /> remedial design of the selected remedy. <br /> • Please amend Section 1.1.0.0.1 to indicate that the purpose of the RI/FS <br /> includes the collection of data to support the feasibility study, the baseline risk <br /> assessment and the remedial design of the selected remedy. For clarification, <br /> the purpose or objectives of the follow-on Phase II investigation should also be <br /> described. The text should also explain if the Phase I and II efforts are <br /> intended to collect all data needed to complete the remedial design or if a <br /> further data collection effort is anticipated following Phase 2. <br /> 10. Paragraph 1.1.0.0.2, 'Purpose", Page 1-1 <br /> It is stated that the primary objective is to confirm the absence or presence of <br /> contamination at each site. Sections 3.1.2.3 and 3.1.2.4 of the Comprehensive RDFS <br /> Work Plan states that statistical tests will be applied to all Phase I data. However, no <br /> tests have been proposed in this document. (See also EPA comment No. 7.) <br /> • What statistical tests will be applied to determine whether the data is adequate <br /> to confirm the presence or absence of contamination at each site? <br /> The second objective of Phase I is to identify sites that are potential sources of the <br /> OU-1 ground-water plume. This is not directly addressed in Section 8, <br /> "Recommendations", or elsewhere in the document. Further, the report does not <br /> graphically relate potential sources of contamination to the OU-1 groundwater plume. <br /> Such a comparison may provide insight on where additional Phase II sampling may be <br /> warranted. <br /> • Please clarify whether Phase I failed to satisfactorily identify these sources, and <br /> if so, include recommendations for Phase II that specifically deal with this <br /> objective. Such source areas may have been placed in the category for <br /> "expedited removal" in Table 7-1, but it is not clear if this has been done. <br /> Please explain the basis for the "expedited removal." <br /> • Please provide a map showing the known extent of the OU-1 groundwater <br /> plume and those SWMUs believed to be contributors to this plume. Determine <br /> if additional Phase If sampling may be warranted based on a comparison of <br /> EPA 14FEE94 4/10 <br />