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tl A S S O C I A T E S I N C On September 21, 1998, an ATC geologist supervised the advancement of five soil borings, SB7 through SB 11, from 5 to 31 feet bgs A site plan showing soil boring locations is included as Figure 2 Sol] samples were collected at five-foot intervals and grab groundwater samples were collected from each boring Samples were analyzed for petroleum hydrocarbons and elevated concentrations of petroleum hydrocarbons were detected in soil and groundwater samples The September 1998 subsurface investigation results are detailed in ATC's Summary Report of Additional Subsurface Investigation, dated November 4, 1998 In January 1999, ATC supervised the advancement of three soil borings around the former excavation area The borings were completed as groundwater monitoring wells Analytical data indicated the soil and groundwater at the site are impacted with total petroleum hydrocarbons as diesel (TPHd) and as gasoline (TPHg) The January 1999 subsurface investigation results are detailed in ATC's Summary Report of Additional Subsurface Investigation, dated April 7, 1999 SAMPLING ACTIVITIES On June 1, 1999, groundwater samples were collected by ATC Associates personnel from monitoring wells MW1 through 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 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 Sequoia Analytical (FLAP Cert No 1210) for chemical analysis of TPHg and TPHd utilizing EPA methods 8015 modified, and benzene, toluene, ethylbenzene, and xylenes (BTEX) utilizing EPA methods 8020 Groundwater well purge and sample logs are contained in Attachment 1 ANALYTICAL RESULTS The groundwater sample collected from well MW2 contained elevated concentrations of TPHg, TPHd, toluene, ethylbenzene, and xylenes The TPHg concentration was 14,900 parts per billion (ppb), the TPHd concentration was 3,150 ppb, and toluene, ethylbenzene, and xylenes concentrations ranged from 16 7 to 3,260 ppb The analytical data for the groundwater sample from well MW2 indicated that the TPHd result contained diesel and an unknown fuel hydrocarbon The groundwater sample collected from well MW 1 contained TPHd at a concentration of 1,150 ppb The analytical data for the groundwater sample from well MW 1 indicated that the TPHd result contained diesel and an unknown fuel hydrocarbon The groundwater sample from well • MW1 did not contain detectable concentrations of TPHg or BTEX The groundwater sample from well MW3 did not contain detectable concentrations of TPHg, TPHd, or BTEX Analytical w\130991quaA1y12gr-1999 doc 2