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approval of the SJCPHS-EHD Total petroleum hydrocarbons as diesel, TPHg, motor oil, <br /> halogenated volatile organic compounds (HVOCs), organic lead, and the gasoline constituents <br /> ' benzene and toluene were not detected in soil samples collected from the borings Low <br /> concentrations of the gasoline constituents ethylbenzene and total xylenes were detected in <br /> soil samples collected from borings MW-2 and MW-3 Total petroleum hydrocarbons as <br /> ' diesel and motor oil were not detected in groundwater samples collected from monitoring <br /> wells MW-1 through MW-3 TPHg was detected in groundwater samples collected from <br /> monitoring wells MW-2 and MW-3, but not from MW-1 BTEX were detected in <br /> groundwater samples collected from monitoring wells MW-1 through MW-3 (Balbi & Chang <br /> April 24, 1989) Balbi & Chang also identified large diameter pumping wells south and east <br /> of the site Balbi and Chang reported detectable concentrations of total petroleum <br /> ' hydrocarbons as gasolme (TPHg) and benzene, toluene, ethylbenzene, and total xylenes <br /> (BTEX) were present in soil and groundwater samples, but the conclusions contained <br /> conflicting information <br /> F From November 16 through November 21, 1989, LH performed an additional site <br /> assessment at the site LH observed the drilling of five six inch diameter soil borings (TB5 <br /> through TB9), and two four-inch diameter groundwater monitoring wells (MW-4 and MW- <br /> 5) This investigation verified the existence of elevated concentrations of gasoline <br /> ' hydrocarbons in soil from boring TB-5, and groundwater beneath the site Gasoline <br /> hydrocarbons were present in soil samples collected from boring TB-5 located on the <br /> northwest portion of the site, at a maximum concentration of 1.2,000 ppm, to a depth of <br /> approximately 30 feet below ground surface (bgs) Gasoline hydrocarbons were not detected <br /> in soil samples collected from boring TB-5 below 30 feet bgs Diesel hydrocarbons were not <br /> detected in soil samples collected from boring TB-5 Non detect to very low concentrations <br /> of BTEX were reported in soil samples collected from borings TB-6 through TB-9 TPHg <br /> ' were not detected in soil samples collected from borings TB-6 through TB-9 Elevated levels <br /> of gasoline hydrocarbons were detected in groundwater samples collected from previously <br /> installed monitoring well MW-2 and newly installed well MW-5 Trace levels of gasoline <br /> 3 hydrocarbons were detected to groundwater samples collected from previously installed <br /> monitoring wells MW-1 and MW-3, and from newly installed well MW-4 LH identified 14 <br /> municipal wells within a one-mile radius of the site Only 3 wells appear to be downgradient <br /> ' of the site, the closest well being approximately 1,300 feet downgradient Also, based on an <br /> F inspection of the excavation sidewalls, LH concluded that Balbi & Chang incorrectly <br /> ' determined the locations of the former USTs LH placed the locations of the former USTs <br /> 10 feet farther south and east than Balbi and Chang's estimated locations (Leedshill <br /> Herkenhoff, Inc January 1990) <br /> E In August 1990, LH drilled three additional soil borings (SB21 through SB23) near TB-5, <br /> located in the northwest portion of the site, in order to evaluate the lateral and vertical extent <br /> ' of petroleum hydrocarbons detected in soil samples collected from TB-5 during the previous <br /> phase of the investigation A 4-inch inner diameter monitoring well (MW-6) was installed in <br /> soil boring SB21 to a depth of approximately 76 feet in order to replace nearby well MW-1, <br /> which had gone dry LH concluded that the results of this phase of the investigation <br /> gronndzOrock lmp 2 <br /> s <br />