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A Mr. Ted Knowles February 6, 1.989 202/799-5027.04 ' SUBSURFACE CONDITIONS Soil encountered during the drilling operations at the site revealed zones containing various combinations of sand, silt, and clay (Figures 3 and 4) . Some of the zones are laterally con- tinuous across the site. The tank pit, as documented in the drill log for 58-1, contains a heterogenous mix of sand, silt, and clay (native backfill) . } The soil contamination at the site appears to be confined to � the tank pit and soil directly below (Figure 5 and 6) . The total volume of contaminated soil {approximately 4,250 cubic yards} was 4 . estimated from the maps and cross sections for the site. A summary of the laboratory results for the soils is presented in Table 1. The results for soil samples collected during the tank excavation revealed that ,the majority of contamination is at the l northwestern end of the tank pit (corresponding to the 12,000- - f gallon unleaded and regular gasoline tanks) . Soil samples analyzed during the. tank removal process revealed benzene concen- - c , trations.ranging between non-detectable (ND) and 41 parts per )! �j million (ppm} at depths between 21 and 34 feet below grade (fbg) Soil samples collected from SB-1 also revealed concentrations of Figasoline hydrocarbons. Analysis of the soil sample collected at 10.5 fbg from SB-1 indicated total petroleum hydrocarbons (TPH) as Si L gasoline concentrations of 3200 ppm. This soil sample was _ collected from native backfill material within the former tank i pit. The soil sample analyzed from 45.5 fbg (native soil) in SB-1 rea revealed TPH as gasoline concentrations of 100 ppm (Figures 5 and 4.# 6) . The majority of the TPH as gasoline components noted in the soil samples from SB-1 are miscellaneous hydrocarbons (Table 1 and } Appendit II) . Soil samples collected from MW-1 through MW-3 { la.#