SITE INFORMATION AND CORRESPONDENCE_1992

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• Draft Soils FS Report Memorandum -2- 17 April 1992 DDRW, Sharpe investigation of USTs included non-fuel wastes that have contaminated soils and ground water. The existing data from the investigation of WMUs and fuel USTs is incomplete because insufficient data have been developed on which to base ground water protective soil cleanup levels. The Soils FS Report does not propose any additional investigation of the WMUs and USTs which is unacceptable. In addition, the level of investigation being performed at DDRW, Tracy far exceeds the level of investigation being performed at Sharpe when the level of investigation of WMUs and USTs should be similar at the two DLA facilities. 2. New contaminant source areas were identified in the UST Report. The UST investigation included tanks which contained wastes or liquids other than fuel : two solvent waste tanks, one pesticide waste tank and eight tanks of waste oils. The preliminary investigation of some of the USTs indicated that ground water has been contaminated by semi-VOCs, PCBs and heavy metals. These data are discussed in more detail in our memorandum on the UST investigation. Many of the USTs which contained non-fuel wastes have only been partially investigated, or not at all . The potential source areas as well as the newly confirmed source areas will require additional investigation and remediation of the ground water and soils. The non-fuel USTs should have been included in the site-wide soil and ground water remedial investigation (RI) . 3. The Draft Soils FS Report indicated that health based risk assessments were used to develop cleanup levels for soils. A health based risk assessment is inadequate to determine whether the contaminated soil will leach and degrade ground water quality and therefore, should not be the only consideration in development of a soil cleanup level . Soil cleanup levels are critical to the remediation of the ground water because unless the sources are adequately abated, contaminants will continue to leach throughout the unsaturated zone and degrade ground water quality. Soils should be remediated to background concentrations, if technically and economically feasible. An environmental fate analysis for each contaminant of concern is needed to determine whether a waste will impact ground water. 4. It appears that little to no analyses for soluble concentrations of contaminants in soils were performed in the investigation of the WMUs and USTs. The cleanup levels proposed in the Draft Soils FS Report appear to be based on total concentrations. Soluble concentrations are needed to determine whether the source areas and underlying contaminated soils will continue to leach contaminants. Soluble concentrations are also needed for use in an environmental fate analysis to determine whether the ground water will be impacted if the wastes remain in-place. Collection of additional soil samples is needed at the WMUs so that soluble concentrations of the contaminants may be determined. 5. Cleanup of soils contamination for any constituents other than lead was not proposed despite the fact that there are very high and often hazardous concentrations of other heavy metals and pesticides in the soils. Because the investigation of the WMUs and USTs is inadequate, it is premature to determine what cleanup level for a particular constituent, other than background levels, is appropriate to be protective of ground water quality. Additional investigation of WMUs and USTs are needed to determine the extent of soil