ARCHIVED REPORTS_XR0006885- CASE 2

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1 ' 16 June 2000 AGE-NC Project No 97-0351 tPage 2 of 4 ' 1-later amber bottles The samples were labeled individually and placed in a chilled container and transported under chain-of-custody to McCampbell Analytical, Inc (MAI), a California Department of Health Services (DHS)-certified analytical laboratory located in Pacheco, California Each sample 1 was analyzed in accordance with • EPA Method 8015m for total petroleum hydrocarbons quantified as gasoline (TPH-g), i ' • EPA Method 8015m for total petroleum hydrocarbons Quantified as diesel (TPH-d), j EPA Method 8020 for volatile aromatic compounds benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether(MTBE), and • EPA Method 8260m for di-isopropyl ether(DIPE), ethyl tertiary butyl ether(ETBE), methyl tertiary'butyl ether (MTBE), tertiary amyl methyl ether (TAME) and tertiary butyl alcohol, (TBA) 3.0. FINDINGS '• Ground water flow direction and gradient were determined from field measurements, hydrocarbon impact on ground water was assessed from results of laboratory analysis 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT ' The relative elevation of ground water in each well was calculated by subtracting the ground water depth from the surveyed relative casing elevation The wells were surveyed relative to the top of well ' MW-1, assigned with an arbitrary elevation of 10 feet above mean sea level The relative ground water elevation data is summarized in Table 1 Ground water flow direction in the area of the western UST was toward the northeast at a gradient of approximately 0 0009 (ft/ft) and the flow direction appears to switch toward the northwest as observed in the area of Building E as depicted in Figure 3 ' The close proximity of the western UST area to the Stockton Deep Water channel may have a significant effect on the local flow direction and gradient Contoured ground water elevations are ' shown in Figure 3 1 • ' Advanced CeoEnvironmental,Inc 1