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� v <br /> D <br /> A S S O C I A T E S I N C <br /> 3.0 BACKGROUND <br /> 3.1 UST Removal <br /> In March 1990, one 1,500-gallon unleaded gasoline underground storage tank (UST), one <br /> ' unleaded gasoline UST of unknown size, and associated piping and dispensing equipment were <br /> removed and transported off-site Laboratory analyses of soil samples collected from beneath the <br /> former 1,500-gallon UST location indicated the presence of detectable concentrations of total <br /> petroleum hydrocarbons Discoloration of the soil and a petroleum hydrocarbon odor were noted <br /> in the field After the tanks were removed, the excavation of the former tanks was backfilled to <br /> grade <br /> 3.2 Subsurface Investigation <br /> Initial Site Investigation <br /> ' On November 14, 1997, an ATC geologist supervised the advancement of two soil bonngs to <br /> 30 feet bgs Analytical results of soil samples collected from the bonngs indicated the <br /> presence of petroleum hydrocarbons. One groundwater sample was collected from each boring <br /> at the depth groundwater was first encountered, approximately 30 feet bgs Groundwater <br /> samples indicated the presence of petroleum hydrocarbons Results are summarized in ATC's <br /> Summary Report of Subsurface Investigation, dated January 14, 1998 <br /> ' Assessment of Hydrocarbon Impacted Soil and Groundwater <br /> On July 13, 1998, an ATC geologist supervised the advancement of four soil bonngs to 26 to 31 <br /> indicated the presence of <br /> feet bgs Analytical results of soil samples collected from the bonngs p <br /> ' petroleum hydrocarbons One groundwater sample was collected from each boring at the depth <br /> groundwater was first encountered Groundwater samples indicated the presence of petroleum <br /> hydrocarbons Results are summarized in ATC's Summary Report of Additional Subsurface <br /> ' Investigation, dated September 9, 1998 <br /> On February 18, 1999, an ATC geologist supervised the installation of three groundwater <br /> ' monitoring wells to 39 to 41 feet bgs Soil bonngs MW1, MW2, and MW3 were completed as <br /> two-inch monitoring wells One soil sample from each boring was collected pnor to completion <br /> of the bonngs as groundwater monitoring wells Soil and groundwater samples contained <br /> ' detectable concentrations of petroleum hydrocarbons Results are summarized to ATC's <br /> Summary Report of Additional Subsurface Investigation, dated June 1, 1999 <br /> ' On September 12 and October 4 and 5, 2001, a geologist from ATC Associates supervised the <br /> advancement of six soil bonngs, SB7 through SB12, to approximately 20 to 25 feet bgs and <br /> one CPT boring to approximately 45 feet bgs Analytical results of soil samples collected from <br /> the bonngs indicated no detectable presence of petroleum hydrocarbons or fuel oxygenates <br /> w 114981VVP0tisl--1080 a doc 2 <br />