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collect four soil samples from each 50 cubic yards of stockpiled soil, composite the groups of four soil samples, and analyze for TPHG and BTEX using a state-certified analytical laboratory 1 dispose or treat excavated soll depending on volume excavated and petroleum hydrocarbon concentrations detected 3.2 Characterize Soil in the Vicinity of Tank E ff As documented previously, TPHD was detected in a soil sample collected f at a depth of 10 feet in exploratory soil boring BH-1 (see Drawing 1). ' When tank E was excavated and removed, a confirmation soil sample was collected and analyzed for TPHG and BTEX. Toluene at a concentration of 0.0113 mg/kg was the only compound detected in the confirmation sam- ple. Because the confirmation sample was not analyzed for TPHD, there is � still aardin uestion regarding g g possible diesel impact to sail beneath and adja- cent to the former location of tank E. EMCON Associates proposes exca- vating and segregating the soil used to backfill the tank excavation. The surface dimensions of the patch covering the tank excavation are reported to be 6 feet by 9 feet. No depth is reported for the confirmation sample collected from the tank excavation for tank E. Based on the reported ' capacity of the tank (550 gallons) and typical burial depths for tanks of this capacity, EMCON Associates believes that the confirmation sample was collected at a depth of 10 feet. Based on the reported surface dimensions and an estimated depth of 10 feet for the excavation, EMCON Associates estimates that roughly 20 cubic yards of backfilled soil will be removed from the tank excavation. EMCON Associates is assuming that this soil is clean imported fill and that chemical characterization is not necessary. Once the fill material is excavated and stockpiled, EMCON Associates ' proposes overexcavating the bottom and sidewalis based on visual and olfactory evidence, and on testing of selected soil samples from the exca- vation using a field test kit. This field test kit is the Hanby Test Kit. Based on the results of the field test kit, confirmation soil samples from the bot- tom and sidewalis of the excavation will be submitted to a state-certified laboratory for analysis of TPHD. At a minimum, one soil sample will be collected for analysis from each of the four sidewalls and from the base of the excavation. p#\f921f920201 a 6 Rev. 0 .tune 1, 1992