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L. <br /> 3.2 Groundwater Sample Collection <br /> Water samples were collected from M1V-? and MW-3 using new disposable plastic bailers. <br /> Samples were collected in three 40-mI EPA vials. Two ]-liter aniber bottles of water were <br /> also collected from MW-3. Samples were placed in a chilled container and transported <br /> under chain-of-custody to Alpha Analytical Laboratories, Inc. in Ukiah, California. Each <br /> sample was analyzed for TPH as gasoline and BTE&X in accordance with EPA methods <br /> 8015m and 602, respectively. The sample from IMM-3 «vas also analyzed for TPH as diesel <br /> and TPH as motor oil in accordance with EPA method 8015m. <br /> 4.0 FINDINGS <br /> 4.1 Ground%s,ater Elevation and Gradient <br /> LThe relative groundwater elevations for the monitoring wells were-calculated by subtracting <br /> the oroundwater depth from the sim,eyed relative casing elevation (Table 1). Groundwater <br /> at the site has dropped an average of 1.75 feet between September 1994 and December <br /> 1994. The drop in groundwater corresponds to normal seasonal fluctuations in the area. The <br /> groundwater .gradient and flow direction were calculated to be 0.004 ft/ft directed N 750 E <br /> (Figure 3). This is consistent with previous calculations. <br /> 4.2 Groundwater Sample Results <br /> No TPH as gasoline was detected in i•INV-2 or MW-3. Concentrations of benzene were <br /> detected in MW-2 and MW-3 at 0.46. ppb and 0.36 ppb, respectively. Concentrations of <br /> toluene were detected in 1111'-2 and M\V-3 at 0.79 ppb and 1.3 ppb. respectively. <br /> Co,rcentratioars of xylenes were detected in M% -2 and i\IW-3 at 0.58 ppb and 2 ppb, <br /> respectively. TPH as diesel was detected in .\1W-3 at 95 ppb: TPH as motor oil was detected <br /> Lin NIW-3 at 400 ppb. The analytical results of the Groundwater samples are summarized in. <br /> Table 2. The laboratory report and chain of custody are included in Appendix B. <br /> L <br /> 5.0 CONCLUSIONS ,k D RECOMMENDATIONS <br /> L5.1 Hydrocarbon Impacted Soil <br /> Petroleum hydrocarbons were detected in soil samples from three of the four borings drilled <br /> in October 1992 at concentrations up to 2,151 ppm. Low concentrations of hydrocarbons <br /> were detected in soil samples from the drilling of the three monitoring wells. Petroleum <br /> hydrocarbons were most recently detected in soil samples collected from beneath the USTs <br /> L at the time of the removal. <br /> LIN A vapor extraction pilot test was conducted on vadose well VW-1 in December 1993. <br /> d C obginl Audis Sema..Inc. 6 <br /> ARCO OR]2-?1!0-1.6 <br /> L <br />