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1 7 L • L ) ATC A S S 0 C I A T E S I N C On February 18, 1999, a geologist from ATC Associates supervised the installation of three groundwater-monitoring wells from 39 to 41 feet bgs Soil borings MW 1, MW2, and MW3 were completed as two-inch monitoring wells One soil sample from each boring was collected and after the groundwater monitoring wells were developed one groundwater sample was collected from each well Soil and groundwater samples contained detectable concentrations of petroleum hydrocarbons Results are summarized in ATC's Summary Report of Additional Subsurface Investigation, dated June 1, 1999 SAMPLING ACTIVITIES On September 6, 2001, ATC personnel collected groundwater samples from monitoring wells MW1, MW2, and MW3 The locations of the monitoring 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 volume of three well casings was purged from each well prior to sampling The wells were allowed to recover and samples were collected from each well using disposable bailers The groundwater matrix samples collected from each well were submitted to State-certified Argon Laboratories (ELAP Cert No 2359) for chemical analysis of total petroleum hydrocarbons as gasoline (TPHg) utilizing EPA method 8015 modified, and benzene, toluene, • ethylbenzene, xylenes (BTEX) and methyl tertiary butyl ether (MTBE) utilizing EPA method 8020 Groundwater well purge and sample logs are contained in Attachment 1 ANALYTICAL RESULTS The groundwater analytical results measured at monitoring well MW 1 showed detectable concentrations of TPHg and BTEX The measured concentration of TPHg at MW 1 was 11,000 gg/L Benzene was detected at 27 gg/L, toluene was detected at 5 6 Vg/L, ethylbenzene was detected at 230 gg/L, and xylenes were detected at 83 µg/L The groundwater analytical results measured at monitoring well MW2 showed detectable concentrations of TPHg, benzene, and xylenes at 460 pg/L, 3 7 pg/L, and 0 6 pg/L respectively The groundwater analytical results measured at monitoring well MW3 showed detectable concentrations of TPHg at 1,100 µg/L, benzene at 2 2 pg/L, ethylbenzene at 11 gg/L, and toluene at 1 2 µg/L The Maximum Contaminant Level (MCL) for benzene, 1 µg/L, was exceeded at monitoring wells MW1, MW2, and MW3 which had detected concentrations of 27 gg/L, 3 7 gg/L and 2 2 Vg/L, respectively MTBE was not detected in any of the samples collected Analytical results are summarized in i Table 2 w lwordpro1149811Repods\3QR-01 doe 2