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18 August 1997 AGE-NC Project No 95-0128 Page 2 of 4 Samples were placed in a chilled container, under ice and transported under chain-of-custody to Mc Campbell Analytical, Inc , (MAI) in Pacheco, California Samples collected from wells MW-1 through MW-3 were analyzed in accordance with EPA methods 5030/8015m for TPH-g, and in I accordance with EPA methods 602 for BTE&X and 8260 for MTBE and other fuel additives All other samples were analyzed in accordance with EPA Methods 5030/8015m for TPH-g, TPH-d, and in accordance with EPA Method 602 for BTE&X and EPA Method 8260 for MTBE and other fuel Iadditives 3.0 FINDINGS 3 1 GROUND WATER ELEVATION AND GRADIENT The casing elevation of each well was surveyed relative to a City of Stockton bench mark of known elevation The elevation of ground water in each well was calculated by subtracting the ground water depth from the surveyed casing elevation The depth of ground water, casing elevations and ground elevations are depicted on Table 1 - Ground Water Elevations The hydraulic gradient was ( � determined by contouring the ground water elevation in each properly screened well Monitoring wells MW-1, MW-2 and MW-3 were not used for the gradient and flow direction calculations as the tops of the screened intervals in these wells are 10 to 14 feet below the top of the saturated zone,and I the ground water elevations in these wells are somewhat aberrant Ground water gradient was calculated to be approximately 0 00487 ft/ft directed approximately N 42° E The ground water elevation contours on the site are illustrated in Figure 3 - Ground Water Elevation I 3 2 ANALYTICAL RESULTS OF GROUND WAFER SAMPLES The highest concentration of TPH-g detected from the site was quantified in the water sample collected from well MW-5 TPH-g and TPH-d were detected in MW-5 at 95,000 and 9,200 ,ug/l (micrograms per liter or parts per billion ppb), respectively The sample also contained BTE&X compounds at concentrations as high as 26,000 ppb, and MTBE at a concentration of 2,100 ppb TPH-g and f PH-d were detected in monitoring wells MW-4 through MW-7 at concentrations as great as 21,000 ppb (TPH-g in MW-4, located at the western boundary of the site) BTE&X constituents were also detected in each of these samples wells at concentrations as high as 8,200 ppb (toluene, MW-4) MTBE was detected in these monitored wells, locally at concentrations as high as 8,400 ppb (MW-6) . TPH-g and TPH-d were quantified in the water sample collected from vapor well VW-1 at concentrations of 13,000 ppb and 11,000 ppb,respectively BTE&X compounds were also detected Advanced GcoEnvironmentai Inc I