SITE INFORMATION AND CORRESPONDENCE_1993-2003

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30%/Draft Submittals -4- 4 May 1993 DDRW, Sharpe 4. Groundwater Monitoring Plan, Page 3-1, Section 3.2.0. 1; We concur that the treatment system can be shutdown when the performance monitoring wells indicate that the aquifer has been restored to the proposed cleanup level (5 ppb for TCE) . However, the monitoring plan does not address when the North and South Balloon treatment systems will be shutdown. We assume that DDRW, Sharpe will use the same evaluation criteria for the North and South Balloon systems as for the Central Area system. DDRW, Sharpe must devise a comprehensive and consistent evaluation methodology for all three areas. 5. Groundwater Monitoring Plan, Page 3-2, Section 3.2.2.1; DDRW, Sharpe proposes to use a mean for four quarters of data to determine if the aquifer cleanup level has been achieved. We do not concur with this proposal . We will accept use of a mean, however, a minimum of two years of data should be considered in the calculation in order to eliminate any seasonal variations in the contaminant concentrations in all wells. We also will accept four consecutive quarters of 5 ppb or less of TCE in all the performance monitoring wells as a demonstration that the aquifer cleanup level has been achieved. Draft - Health and Safety Plan The Draft Health and Safety Plan was reviewed by State Water Resources Control Board, Associate Industrial Hygienist, Jose M. Boria. Mr. Boria's comments are included as an attachment to this memorandum. Draft - Remedial Action Work Plan 1 . Sections 2.0 and 3.0; These sections describe the Remedial Action Teams and Roles and Relationships for the duration of the remedial action. Clarification is needed on the role that AEC will have in the remedial action and how information will be coordinated between the two contracting agencies. 2. Page 9-1, Section 9.0.0.1; This section refers to Figure 9-1 , preliminary schedule for the RA. Figure 9-1 is missing or should refer to Figure 6-2. JDT:jt