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Remedial Investigation Report -12- 8 March 1991 <br /> DDRW, Sharpe <br /> definition of extent of contamination, removal of contaminated soil , and <br /> confirmatory sampling of soil and ground water. <br /> RESPONSE <br /> 1. I concur with this recommendation. The work plan must include plans to perform <br /> an environmental fate analysis, such as the Designated Methodology, to determine <br /> the contaminant concentrations which pose a threat to water quality and to <br /> establish cleanup levels. Hazardous concentrations will not be acceptable as a <br /> cleanup level without an analysis to determine the potential impacts to water <br /> quality. The analytical results of the investigation to define the lateral and <br /> vertical extent of soil contamination must be used in the environmental fate <br /> analysis. We therefore recommend that the soil sample analyses be performed for <br /> soluble concentrations. <br /> RECOMMENDATION <br /> 2. Material from the two sumps should be removed and properly disposed of and the <br /> sumps removed if they are no longer used. Confirmatory soil sampling should be <br /> conducted after removal . <br /> RESPONSE <br /> 2. I concur with this recommendation. We recommend that confirmation samples be <br /> analyzed for soluble concentrations. These analytical results will indicate <br /> whether the residual waste constituents in the unsaturated zone beneath the SWMU <br /> pose a threat to water quality. <br /> RECOMMENDATION <br /> 3. The North Balloon Area Groundwater Treatment System should be operated for 6 <br /> months as planned and an evaluation made as to the need for additional wells. <br /> RESPONSE <br /> 3. I concur with this recommendation. In our letter 5 December 1990 we stated that <br /> the extraction system be monitored and that the existing pumping test data be <br /> reevaluated prior to the installation of any additional extraction wells. In this <br /> letter we raised several concerns with the evaluation of the pumping test data <br /> which must still be addressed. <br /> RECOMMENDATION <br /> 4. Confirmatory soil and ground water sampling should be conducted at the various UST <br /> sites as recommended in Sec. 6.1.2. <br /> RESPONSE <br /> 4. I concur with this recommendation. <br /> RECOMMENDATION <br /> 5. Wells 413A, 420A, 421A, 432A, 438A, 439A, and 456A should be sampled and analyzed <br /> for lead. <br />