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. 27 November 2000 I AGE-NC Project No 98-0520 Page 2 of 3 I22 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-mI volatile organic analysis(VOA)vials contauuug 0 5 m1 18% HCl as a sample preservative and into one 1-liter amber bottle without preservative After collection, the samples were labeled and placed in a chilled container for transportation under chain-of-custody to McCampbell Analytical Laboratory(MAI) of Pacheco, California Each sample was analyzed for I • Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d) in accordance with EPA Method 8015 Modified and • Volatile aromatic compounds - benzene, toluene, ethyl-benzene and total xylenes (BTEX), Iand oxygenate compounds - di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), ethanol, methyl-tertiary butyl ether (MTBE), tertiary-amyl methyl ether (TAME), tertiary- butanol (TBA), methanol, ethanol, ethylene dbromide (EDB) and 1,2-dichloroethane (1,2- DCA) in accordance with EPA Method 8260 Modified • 3.0 FINDINGS I Ground water elevation and flow direction were calculated from field data, the hydrocarbon impact to ground water was assessed by laboratory analysis 3 1 GROUND WATER ELEVATION FLOW DIRECTION AND GRADIENT Depth to ground water at the site ranged from 11 41 to 12 13 feet below the well casing tops The ground water elevations at the site ranged from 87 21 feet to 87 41 feet above mean sea level(n sl) The ground water elevation decreased approxunately 1 64 feet since the last momtormg event The groundwater flow direction and gradient were determmed from the ground water elevation data Contours ofthe groundwater elevation data indicates that the groundwater flow was directedtoward the northeast from the former UST area The ground water gradient on site was calculated to be 0 0029 under the former UST Figure 3 illustrates the contoured ground water elevations I 3 2 HYDROCARBON-IMPACTED GROUND WATER Ile TPH-d was detected in ground water sample collected and analyzed from well MW-3 at a concentration of 77 micrograms per liter (µg/1) MTBE was detected in the ground water samples I collected and analyzed from wells MW-i and MW-4 at concentrations of 4 2 µg/1 and 1 3 µg/l, respectively