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0 0 <br />communication, March 1998). The purpose of this last study was to determine the lateral extent of <br />petroleum hydrocarbon impacts in vadose zone soils and in the first water -bearing zone. <br />During the previous site investigations, soil and groundwater samples were analyzed for petroleum <br />hydrocarbons in the gasoline, kerosene, diesel and motor oil ranges (TPH-G, TPH-K, TPH-D, and <br />TPH-MO), and benzene, toluene, ethylbenzene, and xylenes (BTEX). In addition, the April 1997 soil <br />and groundwater samples were also analyzed for glycol compounds. <br />The subsurface soils consist primarily of interbedded silts and sands. The depth to groundwater varied <br />between the three site investigations, from a low of 4 ft bgs in April 1997 to a high of 13 ft bgs in <br />November 1992. The preliminary data from the November -December 1997 study shows that <br />groundwater flowed to the west at a gradient of 0.002 ft per ft (CH2M Hill, personal communication, <br />March 1998). <br />A summary of the chemical analytical results is presented in Table 1 for the soil samples and Table 2 for <br />groundwater samples. In general, the highest levels of TPH and BTEX have been reported from samples <br />collected in the northeast corner of the facility (i.e., near a former reboiler and sump). Soil samples <br />collected from borings in this area contained TPH-G up to 880 mg/kg, TPH-K up to 1,600 mg/kg, and <br />BTEX up to 1.3 mg/kg, 4.9 mg/kg, 24 mg/kg and 35 mg/kg, respectively. Groundwater grab samples <br />collected from the northeast corner of the facility contained TPH-K up to 1,800 mg/L and BTEX up to <br />1.5 mg/L, 1.4 mg/L, 8.2 mg/L and 19.0 mg/L, respectively. The northwest corner of the facility also <br />contained elevated levels of petroleum hydrocarbons in soil with TPH-K up to 33,000 mg/kg, TPH-D up <br />to 79 mg/kg, and ethylbenzene and xylenes up to 2.1 and 4.6 mg/kg, respectively. A groundwater grab <br />sample collected from the northwest corner of the site contained TPH-G at 0.22 mg/L, TPH-K at <br />0.31 mg/L, benzene at 0.0011 mg/L, ethylbenzene at 0.0085 mg/L and xylenes at 0.023 mg/L. The <br />remainder of the facility contained non-detectable or very low levels of TPH and BTEX in soil and <br />groundwater. <br />402 331-98 63 1-6 <br />