SITE INFORMATION AND CORRESPONDENCE

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0 0 - Draft OU-1 ROD Memorandum -4- 4 June 1993 DDRW, Tracy reduced to semi-annually for the duration of the cleanup (28 years) . This monitoring plan is presented in several sections including Sections 7.1.1.1 and 7.1. 1.3 (page 7-2) , and 7.2.1.1 (page 7-5) . We believe that monitoring should continue to occur on a quarterly basis throughout the remedial action, with the flexibility of specific wells being monitored on a quarterly, semi-annual or annual basis. The identification of the performance monitor wells and the frequency of monitoring should continue to be presented in annual reports as part of a comprehensive site-wide ground water monitoring program already implemented by DDRW, Tracy. The ROD should reflect that the OU-1 Remedial Action groundwater monitoring will be part of a site-wide Comprehensive Monitoring Plan. This comprehensive plan will be annually evaluated to assure that cost effective monitoring is performed, and is sufficient to determine the effectiveness of the groundwater cleanup. The Draft ROD does not clearly state that monitoring will be required for Alternatives 3 and 4. Without monitoring, it would be impossible to determine the effectiveness of the cleanup or to determine when cleanup has been achieved. Monitoring of the remedial action must be included in discussions regarding these Alternatives and the appropriate sections in Chapters 7, 8 and 9. We are not opposed to the use of quarterly monitoring for the first two years and semi-annual monitoring in all of the monitor well for 28 years for the purposes of estimating costs. Sections 7.1.2.7 (page 7-4) and 7.2.2.7 (page 7-8) should be revised to state that this monitoring network was proposed for cost estimate purposes only. 5. Applicable or Relevant and Appropriate Requirements. ARARs are presented in Chapter 10 of the Draft ROD. In addition, the Board's ARARs are discussed in Section 4.2.5. We are pleased that DDRW, Tracy acknowledges State Water Resources Control Board Resolution No. 68-16 (Anti-Degradation Policy) as an ARAR and that use of BPT satisfies this ARAR (page 4-3) . We have reviewed Tables 10.2-1 and 10.2-2 which identifies and summarizes the federal and state ARARs and have several comments that should be considered for the Final ROD. Our specific comments are discussed below: State Board Resolution No. 92-49; Policies and Procedures for Investigation, Cleanup and Abatement of Discharges Under Water Code Section 13304. Resolution 92-49 is a To-Be-Considered (TBC) requirement until it has been formally promulgated. Table 10-2.2 (page 5) should be revised. One of the intents of this resolution, as well as portions of Chapter 15, is to cleanup to background if technically and economically feasible. Because the aquifer cleanup levels have been agreed be set at the Primary MCL we will require that DDRW, Tracy commit to an analysis to determine if it is technically and economically feasible to cleanup to lower concentrations than the Primary MCLS in order to meet this portion of the ARAR or TBC. This analysis may be done with a predictive model or may be done as data are gathered during the cleanup and as part of the five year review process.