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LM LEEDSHILL HERKENHOFF INC Based on procedures and recommendations established in the LUFT Manual , the leaching potential analysis score of 44 establishes the following maximum allowable concentration for BTX&E and TPH which can be left in place without posing a threat to groundwater resources. Benzene 0.3 ppm Toluene 0.3 ppm Ethylbenzene 1.0 ppm Xylenes I.0 ppm TPH as gasoline 100 ppm As presented in Table 1, only samples collected from T85 in the northwest corner of the site produced gasoline constituent levels in excess of the LUFT Manual guidelines to a depth of between 20 and 25 feet. In general , the northwest portion will require further investigation. Samples collected from all other soil borings indicated non detectable petroleum hydrocarbon concentrations or concentrations orders of magnitude below the LUFT manual guidelines. The second analysis in the LUFT Manual , the general risk appraisal , relies on generalized environmental fate and chemistry data and some site-specific information. According to the LUFT Manual instructions, the general risk appraisal is to be terminated at the depth where constituents are non-detectable, or below a level of 0 3 ppm. Since all of the samples with the exception of TB5 have levels below 0.3 ppm, the general risk appraisal also indicates that the cumulative impacts of these trace residual BTX&E and TPH concentrations remaining in the soil do not pose a threat to the groundwater resources of the area. 5.2 EVALUATION OF EXCAVATED SOILS As discussed above, based on the LUFT Manual leaching potential analysis performed in Section 5. 1, the following maximum residual gasoline constituent levels are allowable, and do not pose a threat to the groundwater resources of the area. Benzene 0.3 ppm Toluene 0.3 ppm Xylene 1 .0 ppm Ethylbenzene 1 0 ppm TPH as gasoline 100 ppm A presented in Section 2.2, samples collected by BCA from the former tank excavation below a depth of four feet indicated non-detectable concentrations of BTX&E and TPH. As illustrated in Table 3, all representative soil samples collected from the excavated soil stockpile and the BCA drums indicated either non detectable levels of petroleum hydrocarbons, or residual levels which were orders of magnitude less than maximum allowable concentrations. The second analysis, the general risk appraisal , was performed assuming that the excavated soil could be used as backfill material for the current open -24-