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petroleum hydrocarbons (TPHg) and benzene, toluene, ethylbenzene, <br /> and total xylenes (BTEX) were present in soil, but the conclusions <br /> contained conflicting information (Leedshill-Herkenhoff, September <br /> 1990) . <br /> TPHg were detected in soil samples collected from a depth of <br /> approximately 2 feet below ground surface (bgs) from boring TB-1, <br /> located near the area of the former USTs, at a maximum <br /> concentration of 196 parts-per-million (ppm) . soil in the former <br /> k UST cavity was then overexcavated to a depth of approximately 4 <br />'4 feet bgs and stockpiled on-site. The excavation was left open <br /> (Kennedy/Jenks, October 21, 1992) . <br /> I <br /> In January 1989, Balbi & Chang drilled four soil borings (MW-1, MW- <br /> 2 , MW-3, and B-4) and installed monitoring wells (MW-1 through MW- <br /> 3) in three of the borings. Total petroleum hydrocarbons as <br /> gasoline, diesel and motor oil were not detected in soil samples <br /> collected from the borings. Volatile organic compounds (VOCs) , <br /> organic lead, and the gasoline constituents benzene and toluene <br /> were also not detected in soil samples collected from the borings. <br /> Low concentrations of the gasoline constituents ethylbenzene and <br /> total xylenes were detected in soil samples collected from borings <br /> MW-2 and MW-3 . Total petroleum hydrocarbons as diesel and motor <br /> oil were not detected in groundwater samples collected from <br /> monitoring wells NW-1 through MW-3 . TPHg was detected in <br /> groundwater samples collected from monitoring wells MW-2 and MW-3 , <br /> but not from MW-l. BTEX were detected in groundwater samples <br /> collected from all three monitoring wells (Balbi & Chang April 24, <br /> 1989) . Balbi & Chang also identified water supply wells south and <br /> east of the site. <br /> From November 16 through November 21, 1989, Leedshill-Herkenhoff, <br /> Inc. (LH) performed additional site assessment at the site. LH <br /> observed the drilling of five six inch diameter soil borings (TB5 <br /> through TB9) and two four-inch diameter groundwater monitoring <br /> wells (MW-4 and MW-5) . This investigation confirmed the presence <br /> of petroleum hydrocarbons in soil and groundwater. Petroleum <br /> hydrocarbons were present in soil samples collected from boring TB- <br /> 5 (located on the northwest corner of the site) with a maximum <br /> concentration of 12,000 ppm at a depth of approximately 15 feet <br /> below ground surface (bgs) . Petroleum hydrocarbons were not <br /> detected in soil samples collected from boring TB-5 below 25 feet <br /> bgs. Elevated levels of gasoline hydrocarbons were detected in <br /> groundwater samples collected from previously installed monitoring <br /> well MW-2 and newly installed well MW-5. Minor levels of gasoline <br /> hydrocarbons were detected in groundwater samples collected from <br /> previously installed monitoring wells MW1 and MW-3, and from newly <br /> installed well MW-4 . LH identified 14 municipal wells within a <br /> one-mile radius of the site. In December 1989 the groundwater <br /> gradient on-site was due east with a magnitude of .005. Earlier <br /> measurements showed a gradient of . 006 ft/ft to the northeast in <br /> July of 1989 and . 005 ft/ft to the southeast in November 1989. <br /> 2 <br />