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A 1. 3 . A S S O C I A T E S 1 N C In August 1995, Smith Technology conducted a subsurface site investigation to further define the extent of contamination in groundwater at the site Smith Technology supervised the installation of monitoring wells MW4, MW-5 and MW-6 These three new wells were developed and sampled along with monitoring wells MW-I, MW-2, and MW-3 Analytical results of groundwater samples from the six monitoring wells indicated the presence of elevated concentrations of petroleum hydrocarbons in the vicinity of wells MW-3 and MW-6, on the northeast corner of the site In November 1998, ATC conducted a subsurface site investigation to evaluate the vertical and horizontal extent of hydrocarbon impacted soil ATC supervised the installation of three soil borings SBI, SB2, and SB3 from approximately 30 to 50 feet bgs Analytical results of soil samples indicated the vertical extent of soil contamination had been defined, but the horizontal extent of impacted soil was not fully defined on the northeast corner of the site Site activities are summarized in ATC's Summary Report of Additional Subsurface Investigation, dated January 27, 1999 SAMPLING ACTIVITIES On February 1, 2001, ATC personnel collected groundwater samples from morutoring wells MW- I through MW-6 The locations of the momtonng wells are shown on Figure 2 Prior to collection of groundwater samples, the depth to water, pH, electrical conductivity, and temperature were measured in the monitoring wells and recorded A minimum of three well casing volumes were purged from each well prior to sampling The wells were allowed to recover and samples were collected from each well using dedicated disposable bailers The groundwater samples collected from each well were submitted to State-certified Argon Laboratories (FLAP cert no 2359) for analysis of total petroleum hydrocarbons as gasoline (TPHg) utilizing EPA method 8015, benzene, toluene, ethylbenzene, and total xylenes (BTEX) utilizing EPA method 8020, and methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), dr-isopropyl ether (DIPE), tertiary butyl alcohol (TBA), and tertiary amyl ether (TAME) utilizing EPA method 8260 Groundwater well purge and sample logs are contained in Attachment I ANALYTICAL RESULTS The samples from wells MW-4, MW-5, and MW-6 contained no detectable concentrations of TPHg, BTEX, or oxygenate fuel additives TPHg and BTEX were detected in the sample from well MW-3 MTBE was not detected in the sample from well MW3 although the method detection linut in the sample was elevated due to dilution factors The sample from well MW-2 contained TPHg and very low concentrations of toluene, ethyl benzene, and xylenes Well MW-1 contained only MTBE at a concentration below the Maximum Contaminant Level (MCL) A summary of analytical results is presented in Table I Laboratory data sheets and chain-of- custody documentation are contained in Attachment 2 w 162605\quaAyugr-2001 doe 2