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� G 30 July 2003 • AGE-NC Project No 99-0584 Page 6 of 8 3 12 Collection and Analysis of Ground Water Samples Water samples were collected from each monitoring well using the dedicated, disposable polyethylene bailers after allowing the wells to achieve a mimmum 80%recovery of the pre-purge water volume, the bailers are disposed of after one use and require no decontaminating, thereby minimizing cross contamination due to sampling devices Each water sample was transferred into three 40-m1 EPA-approved VOA vials containing 0 5 ml 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 ELaboratory(NW,a State of California Department of Health Services-certified analytical laboratory in Pacheco, California, and analyzed for • Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d) in accordance with EPA Method 8015 Modified and • Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether (MTBE) in accordance with EPA Method 8020 32 FINDINGS Ground water elevation and flow direction were calculated from field data, the hydrocarbon impact to ground water was assessed by laboratory analysis 1 3 2 1 Ground Water Gradient and Flow Direction ' Depth to ground water at the site ranged from 12 92 to 13 60 feet below the well casing tops The ground water elevations at the site ranged from 85 67 feet(MW-5)to 85 86 feet(MW-2 and MW-3) above mean sea level (MSL) The ground water elevation increased approximately 0 75 feet smce the last monitoring event ' The ground water flow direction and gradient were determined from the ground water elevation data Contours of the ground water elevation data indicates that the ground water flow was directed toward the northeast, at a gradient of approximately 0 003 ft/ft Figure 7 illustrates the contoured ground water elevations ' Advanced GcoEnviroamental,Inc