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, <br /> C A M B R I A <br /> the dispenser excavation contained 2 7 ppm TPHg Complete results of the UST removal <br /> are documented in the Fugro April 19, 1995 Underground Storage lank Closure Report <br /> During February 1996, Enviros, Inc (Enviros) drilled two GeoProbe® borings (GP-1 and <br /> GP-2) in the vicinity of the UST complex to investigate the extent of petroleum <br /> hydrocarbons detected during the December 1994 tank removal activities Enviros drilled <br /> one angle boring beneath the UST complex and one vertical boring adjacent to the UST <br /> complex Soil samples collected from GP-1 and GP-2 did not contain detectable <br /> concentrations of petroleum hydrocarbons but did contain MTBE at concentrations of <br /> 2 2 and 29 ppm, respectively This investigation is described in Enviros' May 8, 1996 Soil <br /> Boring Installation Report <br /> During January 1999, Cambria drilled five soil borings (SB-1 through S13-5) in the vicinity of <br /> the UST complex TPHg was detected only in boring SB-1 at a concentration of 3 17 ppm <br /> No benzene was detected in any of the soil borings MTBE was detected in all borings at <br /> concentrations ranging from 0 00807 to 92 9 ppm Groundwater samples were collected <br /> from borings S13-3 and S13-4 Groundwater samples from S13-3 contained 46,000 parts per <br /> billion (ppb) TPHg, 243 ppb benzene, and 28,400 ppb MTBE Groundwater samples from <br /> S13-4 contained 6,610 ppb TPHg, 63 6 ppb benzene, and 9,080 ppb MTBE These results are <br /> summarized in Cambria's June 9, 1999 Site Investigation Report <br /> Technical Rationale for Proposed Scope of Work <br /> • The source area of petroleum hydrocarbons and MTBE detected during the 1994 tank <br /> removal, the February 1996 soil investigation, and the January 1999 soil and <br /> groundwater investigation has not been identified <br /> • The vertical extent of petroleum hydrocarbons and MTBE in the source area has not <br /> been delineated <br /> • To identify the source area, four soil borings and three groundwater monitoring wells <br /> are proposed at the locations shown on Plate 2 Soil and groundwater samples will be <br /> collected and analyzed to delineate the extent of petroleum hydrocarbons and MTBE <br /> in the vicinity of the UST complex, dispenser islands and piping areas <br /> 241-0955 2 <br />