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MAY '.$. 1 00 _0 27A14 .uJ NO. 384 I <br /> • V <br /> communication, March 1908). The purpose of this last study was to determine the lateral extent of <br /> petroleum hydrocarbon im;:acts in vadose zone soils and in the first water-bearing zone. <br /> During the previous site i[n,estigations, 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 consis-l: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(GH2M Hill,personal communication,' <br /> March 1998). <br /> A summary of the chemica;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 /> 1 collected in the northeast corner of the facility(i.e., near a former reboiler and sump). Soil samples <br /> y collected from borings in tfi is area contained TPH-G up to 880 mg/kg,TPH-K up to 1,600 mg/kg, and <br /> BTEC up to 1.3 mg/kg,4.9.mgAg,24 mg/kg and 35 mg/kg, respectively. Groundwater grab samples <br /> 1 collected from the northeas,corner of the facility contained TPH-K up to 1,800 mgfL 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 Ofpetroleum hydrocarbons in soil with TPH-K up to 33,000 mg/kg,TPH-D up <br /> to 79 mykg,and ethylbenzz-ne and xylenes up to 2.1 and 4.6 m&14, respectively. A groundwater grab <br /> sample collected from the rorthwest corner of the site contained TP14-0 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 co:itained non-detectable or very low levels of TPH and BTEC in soil and <br /> groundwater. <br /> 402 331.98_b3 1-6 <br /> 1 <br />