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14 11 <br /> C A M B R I A <br /> i <br /> dispenser Soil samples collected from beneath the product lines and the new UST excavation <br /> did not contain detectable concentrations of TPHg or benzene Complete results of the tank <br /> removal are presented in Delta Environmental Consultants, Inc 's (Delta's) April 6, 1989 Tank <br /> Closure Report <br /> 1989 Site Investigation During August 1989, Delta drilled six soil borings and converted three <br /> of the bonngs to groundwater monitoring wells (MW-1 through MW-3) The three well bonngs <br /> and the two soil bonngs drilled near the northwestern (SB-1) and southern dispensers (SB-2) did <br /> not contain detectable concentrations of TPHg or benzene The soil boring drilled in the former <br /> UST excavation (SB-3) contained maximum concentrations of 0 3 ppm TPHg and 0 005 ppm <br /> benzene Investigation results are documented in Delta's October 20, 1989 Phase I <br /> Hydrogeologic Assessment Report <br /> 1990 Problem Assessment Report During October 1990, Delta submitted a Problem Assessment <br /> Report requesting case closure <br /> 1997 Site Investigation During December 1997, Cambria drilled two soil bonngs near the <br /> northwestern dispenser(B-1 and B-2) Soil samples from B-1 contained TPHg concentrations up <br /> to 2,100 ppm and benzene up to 0 57 ppm, with the highest concentrations at 17 feet below grade <br /> (fbg) Soil samples from boring B-2 did not contain detectable concentrations of TPHg or <br /> benzene, and neither boring contained detectable concentrations of fuel oxygenates Water was <br /> encountered in boring B-1 at approximately 14 7 fbg Because depth to groundwater beneath the <br /> site historically ranges from approximately 29 to 60 fbg, the water observed in boring B-1 is <br /> considered perched A grab water sample from this perched zone contained 110,000 parts per <br /> billion (ppb) TPHg and 260 ppb benzene Fuel oxygenates were not detected in this water <br /> sample The investigation is summarized in Cambria's March 10, 1998 Site Investigation <br /> Report <br /> 1998 Upgrade Activities During March 1998, Cambria inspected the site during fuel and waste <br /> oil UST overspill upgrade activities No soil samples were collected Cambria submitted a <br /> 98 Upgrade Site Inspection Report on October 15, 1998 <br /> Groundwater Monitoring Program There are currently three monitoring wells onsite (MW-1 <br /> through MW-3) that are sampled quarterly During the first quarter 2003 sampling event, <br /> 100 ppb TPHg were detected in MW-2, 0 5 ppb benzene were detected in MW-3, and 13 ppb <br /> methyl tertiary butyl ether (MTBE) were detected in well MW-1 MTBE was not detected in <br /> i <br /> wells MW-2 or MW-3 The groundwater flow direction during the first quarter 2003 was to the <br /> 0832 2 <br />