SITE INFORMATION AND CORRESPONDENCE_1992

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r Draft Ground Water ROD Memorandum -2- 21 May 1992 DDRW, Sharpe produced. The UST investigation began only recently (within the last year) and additional investigation is needed for the fuel USTs. Therefore, BTXEs should not be included in this ROD or the ROD should reflect more stringent aquifer cleanup levels. Cleanup Levels Versus Treatment Standards. The ROD presents the aquifer cleanup levels in Table 8 (page 43) . The Table lists the cleanup levels as treatment goals. In addition, the text in the ROD uses the terms "cleanup level " interchangeably with "treatment goals" . These terms are not interchangeable. Cleanup levels refer to the concentration at which the aquifer must be restored. Treatment goals should be replaced with "performance standards" . In our 20 December 1991 letter on the Draft Proposed Plan and again in our 6 March 1991 letter on the Proposed Plan sent out during the public comment period, we addressed the issue of cleanup levels. Sharpe did not adequately address this concern and we did not approve the Proposed Plan. The Draft ROD should be revised to include two tables: one for the aquifer cleanup level and one for the treatment standards. We have previously written regarding our concern with the cleanup levels for xylene and bromacil . These cleanup levels are discussed in more detail below. The effluent limit for volatile organic constituents (VOCs) in the existing National Pollutant Discharge Elimination System (NPDES) permit is non-detect. Therefore, the performance standard for all VOCs would be the detection limit (0.5 micrograms per liter (µg/1 ) or lower, depending on the analytical method) . We will require that best available technology (BAT) be applied for any discharge to surface water or to land and whether through reinjection or to a percolation pond. We have enclosed the draft substantive requirements for a general discharge of the treated VOC contaminated ground water to land. We intend to tailor the requirements to site specific conditions and finalize these requirements prior to the final ROD. These substantive requirements can be attached as an appendix to the ROD and should be incorporated by reference in the appropriate section on ARAR compliance for the selected Remedial Action. Table 8 also lists the cleanup level for nitrates. An additional "cleanup level " of background must be added to the table for where the treated ground water is to be reinjected. Xylene and Bromacil Cleanup Levels. Table 8 lists the proposed aquifer cleanup levels for xylene and bromacil . We have previously written in our review of the Draft Final Ground Water FS Report (letter dated 2 January 1992) that the aquifer cleanup levels for xylene and bromacil should be 20 µg/l and 90 µg/l , respectively. In particular, we are concerned that 20 µg/l has not been accepted as the cleanup level for xylene. We require UST owners and operators to cleanup ground water to this concentration and will require that the military do the same. It is also unclear why 20 µg/l is unacceptable when the cleanup level for benzene has been proposed for 0.5 Ag/l which is more than two orders of magnitude less than 20 Ag/l for xylene. This cleanup level is anticipated to be technically achievable if benzene is removed to this concentration. Furthermore, a cleanup level of 40 µg/l for toluene, the Secondary Maximum Contaminant Level , has been proposed and accepted by the regulatory agencies. It is unclear then why 20 µg/l is an unacceptable cleanup level for xylene.