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' 3.2 Groundwater Sample Collection Water samples were collected from MW-2 and MW-3 using new disposable plastic bailers ' Samples were collected in three 40-m1 EPA vials Two Miter amber bottles of water were also collected from MW-3 Samples were placed in a chilled container and transported under chain-of-custody to Alpha Analytical Laboratories, Inc in Ukiah, California Each ' sample was analyzed for TPH as gasoline and BTE&X in accordance with EPA methods 8015m and 602, respectively The sample from MW-3 was also analyzed for TPH as diesel ' and TPH as motor oil in accordance \lith EPA method 8015m ' 40 FINDINGS 41 Groundwater Elevation and Gradient ' The relative groundwater elevations for the nionitoiing wells were calculated by subtiacting the groundwater depth froni the surveyed ielative casing elevation (Table 1) Groundwater ' at the site has dropped an average of 1 75 feet between September 1994 and December 1994 The drop in gioundwatei coiiesponds to normal seasonal fluctuations in the area The groundwater gradient and flow direction «eie calculated to be 0 004 ft/ft directed N 75° E ' (Figure 3) This is consistent vt ith pre\nous calculations 4.2 Groundwater Sample Results as To TPH gasoline was detected iii ININV-2 or MW-3 Concentrations of benzene \sere No detected in MW-2 and MW-3 at 0 .16 ppb and 0 36 ppb, respectively Concentrations of toluene weie detected in MW-2 and MW-3 at 0 79 ppb and 1 3 ppb, iespectivel� Coacentrations of xylenes were detected in MW-2 and NNW-3 at 0 58 ppb and 2 ppb, respectively TPH as diesel was detected in MW-3 at 95 ppb TPH as motor oil \\as detected ' in NNW-3 at 400 ppb The analytical results of the groundwater samples are suminaiized in Table 2 The Iaboiatory report and chain of custody aie included in Appendix B ■ 5.0 CONCLUSIONS AND RECOMMENDATIONS ' 5.1 Hydrocarbon Impacted Soil Petroleum liydiocaibons were detected in soil samples fiom three of the four borings drilled ■ in October 1992 at concentrations up to 2,1$1 ppm Low concentrations of trydrocait)ons were detected in soil samples fiom the drilling of the three monitoring wells Petroleum hydrocarbons were most recently detected in soil samples collected from beneath the USTs at the time of the removal A vapor extraction pilot test was conducted on vadose well VW-1 in December 1993 C-&B-1 Aad I km- 6 AACO OR12 VIVO t t ■