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' 28 April 1995 AGE-NC-95-0103 Page 3 of i l ' 0 5 gallon Purge water was placed in 55-gallon drums and stored on-site Stabilization data are included in Appendix. A ' A water sample was collected from each .yell using a new disposable plastic bailer Each sample was collected in four 40-m1 VOA-vials presened with hydrochloric acrd, placed in a chilled container and transported to a state-certified laboratory ' 32 LABORATORY ANALYSIS OF GROUND 1VATER SAMPLES The Nvater samples were transported under chain-of-custody to Alpha Analytical Laboratories ' (AAL) in Ukiah for analysis The water samples i.+ere analyzed for TPH-g, BTE&X and halogenated volatile organics in accordance mth EPA methods 8015, 602 and 601, respectsely ' TPH-g was detected in MW-1 and 1.111'-2 at concentrations of S60 pgil (parts per billion ppb) and 62 ppb respects ely Benzene was detected in MW-2, M1V-3 and MW-4 at concentrations of 0 65 ppb, 0 67 ppb and 0 64 ppb, respects\ely Toluene was detected in NNW-2 at a concentration ' of 0 72 ppm Ethylbenzene and xylenes N\ere not detected in any of the water samples The anal tical results are summai ized in Table 3 The laboratory report and chain-of-custody are included in Appends\ B Se\eral halogenated \olatile organic compounds N\ere detected in each «ell including 1,1-Dichloi oethane 1,2-Dichloroethane, Ti iehloroeth\1ene and 1,1-DichloroetliN leve The laborator) report for the halogenated hydi ocai bons is included in appendrr B 3 3 GROUND WATER CONDITIO\`S At the time of monitoirng, the depth to ground \pater at the site was apprommately 78 feet Since Apr sl 1994, ground water depth has risen an aN erage of 1 43 feet at the site This is consistent with a regional rise in ground water between 1994 and 1995 Well casing elevations and ground water depth data are summarized on Table 1 The hydr aiilrc gi adient calculated from the 27 January 1995 measurements is 0 013 ft/ft, oriented S 60 E (Figure 3) This gradient is slightly steeper than the previous gradient (0 0071 ft/ft, April 1994) iIn October 1993 and January 1994, MW-3 was the dawn-gradient well However, the ground water flow dii ection has since changed to the southeast, resulting in MW-4 as the down-gradient well Historically, the flow direction at the site has varied from northeast to southeast It is uncertain whether the shift in ground water flow direction is the result of seasonal changes or localized agricultural or domestic water well pumping