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I10 December 2001 AGE-NC Project No 98-0448 ' Page 4 of 8 4.0. FINDINGS AGE determined ground water flow direction and gradient from the field data collected on 24 July 2001, the contaminant impact to ground water was assessed from the laboratory data From field data collected at the SVE remediation system between 01 July and 30 September 2001, I AGE determined the average TPH-g concentration, the average flow rate and calculated the approximate mass and volume of hydrocarbons removed 4 1 GROUND WATER ELEVATION AND GRADIENT The depths to ground water in wells MW-1, MW-4A, MW-4B, MW-6 and MW-8 were measured between 17 69 and 20 43 feet below the tops of the well casings Ground water elevations at the site were calculated to be between 8 97 feet and 11 02 feet below mean sea level, ground water elevations are depicted in Figure 3 Ground water elevation at the site decreased an average 0 34 feet between the April 2001 and the July 2001 ground water monitoring events lie The general ground water gradient at the site was calculated to be approximately 0 016 ft/ft or less, or approximately 85 feet per mile, directed towards the south-southwest (Figure 3) 1 4 2 LABORATORY RESULTS OF GROUND WATER SAMPLES TPH-g was detected in water samples collected from wells MW-1, MW-2, MW-4A, MW-4B and MW-6 at concentrations as high as 61,000 micrograms per liter (µg/1), the highest TPH-g concentration in the first water one was 25,000 ug/l in MW-2 The laboratory reported the MW-1, MW-2,MW-4A and MW-4B samples contained significant unmodified or weakly modified gasoline and the MW-6 sample displayed one to a few isolated peaks present in the sample chromatogram The inferred extent of dissolved TPH-g is depicted in plan view in Figure 4 Various BTEX compounds were detected in wafer samples collected from MW-1, MW-2, MW-4A, "�- MW-4B and MW-6 at concentrations as high as 7,800,ug/l, the greatest benzene concentration was detected in the sample collected from MW-4B at a concentration of 4,100µg/1 The highest benzene concentration in the first water zone was 400 ug/l in MW-2 IMTBE was detected in a water sample collected from MW-4B at a concentration of 25 µg/l No other fuel oxygenated or lead scavenger compounds were detected by laboratory analysis Previous Iand current analytical results of ground water monitoring well samples are summarized in Tables 2 IAdvanced GeoEnvironmentaI,Inc