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1 Mu1LiEfiS lIESGNEPS•W'SLyT1NT5 ' 2.3 CONCLUSIONS BH-13 was installed on the southern edge of the former tank excavation A cross section showing contaminant concentrations in BH-13 and two other soil borings completed prior to this ' investigation on the southern edge of the former excavation is presented on Figure 2-1 As indicated on the cross section high concentrations of petroleum hydrocarbons are present below the static water level at BH-13 at 45 5 ft to 60 5 ft bgs Groundwater or soil analytical data from below 30 ft bgs in the immediate vicinity of the former ' tank excavation is available from MW-2, MW-2A, and BH-13 High concentrations of petroleum hydrocarbons have been detected in groundwater samples collected from MW-2A ' which is screened from 40 ft to 60 ft bgs (Roy F Weston, Phase III Site Investigation Report, August 1995) High concentrations of petroleum hydrocarbons were also detected in a ' groundwater sample collected from MW-2 which is screened from 30 ft to 45 ft bgs, however MW-2 was only sampled once before it went dry (Roy F Weston, Results Summary and Final Work Plan Amendment, 22 June 1995) Groundwater analytical data from below 30 ft bgs downgradlent of the former tank excavation is available from wells MW-3A, MW-7 and MW-8 The last time these wells were sampled (July 1995) benzene (0 59 ug/L) and TPH-G (0 82 mg/L) were detected in well MW-8 ' However, since no petroleum hydrocarbons were detected in MW-3A and MW-7 the contaminants detected in MW-8 are not likely related to the former underground storage tanks ' In summary, high concentrations of petroleum hydrocarbons are present in groundwater and in soil collected from below the static water level (below 37 5 ft bgs) in the immediate vicinity of ' the former tank excavation High concentrations of petroleum hydrocarbons in groundwater likely extend downgradlent past MW-2 but do not reach MW-3A or MW-7 ' LWIMMOmlSJOVOI5A IST 9 Ocnober 19%