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' 14 December 1998 AGE-NC Project No 96-0254 Page 2 of 4 Appendix A Purged water was stored on-site in labeled 55-gallon drums 27 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Water samples were collected from each well using a new disposable plastic bailer Each water sample was transferred into three 40-m1 VOA vials and one 1-liter amber bottle After collection, the samples were labeled and placed in a chilled container for transportation under chain-of-custody to McCampbell Analytical, Inc (MAI), a California Department of Health Services (DHS)-certified analytical laboratory in Pacheco, California Each sample was analyzed for • Total petroleumm hydrocarbons quantified as gasoline and as diesel (TPH-g and TPH-d) by EPA Method 8015 Modified, • Volatile aromatic compounds (benzene, toluene, ethylbenzene and total xylenes BTEX) by IEPA Method 8020 and • Oxygenated fuel additive, di-isopropyl ether (DIPS), ethyl tertiary butyl ether (ETBE), '• methyl tertiary-butyl ether (MTBE), tertiary amyl methyl ether (TAME) tertiary butyl alcohol (TBA) by EPA Method 8260 Modified 3.0 FINDINGS Ground water was inferred to be flowing toward the north, significant hydrocarbon concentrations were detected only in the ground water samples collected from one dual-completed monitoring well and a minor concentration of one fuel additive was detected in one ground water sample collected from the same well 3 1 GROUND WATER ELEVATION AND GRADIENT The ground water elevation in each well was calculated by subtracting the depth to ground water from the surveyed casing elevations (Table 1) Contours of the ground water elevation data suggest Ia flow direction toward the north, shifting down-gradient toward the north-northeast (Figure 3) The ground water gradient on 28 September 1998 was calculated to be an average of 0 007 foot/foot or 41 feet/mile directed toward the north from the area of the former USTs toward well MW-1 Ground water gradient was also calculated to be an average of 0 006 foot/foot or 31 feet/mile on the north end of the site and under Toste Road Ground water elevation data is illustrated on Figure 3 Advanced GcoEmiron mental Inc I