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1 ' 25 November 2002 AGE-NC Project No 98-0448 Page 4 of 8 From field data collected at the SVE remediation system between 1 i June 2002 and 11 September ' 2002, AGE determined the average TPH- concentration and the aver g g age flow rate and calculated the approximate mass and volume of hydrocarbons removed 1 ' 4 1 GROUND WATER ELEVATION AND GRADIENT The depths to ground water were measured at between 17 61 and 21 85 feet below the tops of the ' well casings (Table 2) Ground water elevations at the site were calculated to be between 8 09 feet (MW-4A) and 12 44 feet (MW-4B) below mean sea level (Table 2), ground water elevations are depicted in Figure 3 Ground water elevation at the site decreased an average 1 23 feet between the ' May 2002 and the August 2002 ground water monitoring events The ground water flow direction was inferred to be southwest, at a low gradient of approximately ' 0 006 ft/ft north of well MW-4A, but steepening to approximately 0 02 ft/ft south of MW-4A (Figure 3) A ground water mound was interpreted at the IAS location based on the ground water elevation at MW-4A,however,there is the possibility that this very high ground water anomaly may '• be due to a depth measurement error 4 2 LABORATORY RESULTS OF GROUND WATER SAMPLES TPH-g was detected in water samples collected from wells MW-2, MW-4A and MW-4B at concentrations as high as 10,000 micrograms per liter(ug/l),the highest TPH-g concentration in first water was detected from MW-2 The laboratory reported that the sample chromatograms all contained significant unmodified or weakly modified gasoline The inferred extent of dissolved TPH-g is depicted in plan view in Figure 4 ' Various BTEX compounds were detected in water samples collected from MW-2, MW-4A and MW-4B at concentrations as high as 2,200 µg/1 xylene (MW-2), the maximum benzene concentration was detected in the sample collected from MW-2 at a concentration of 77µg/1 MTBE was detected in the water sample collected from MW-4B at a concentration of 2 4µg/l,DIPE was detected in the sample collected frorn MW-1 at a concentration of 96,ug/l, TBA was detected on the sample collected from MW-4A at a concentration of 9µg/1 No other fuel components were detected by laboratory analysis Previous and current analytical results of ground water monitoring well samples are summarized in Tables 3 and 4 The laboratory reports(McCampbell Analytical Inc Work Order 0208347) and chain-of-custody forms are presented in Appendix C • Advanced GeoEnvironmental,Inc