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22 April 2002 <br /> AGE-NC Project No 98-0448 <br />' Page 4 of 8 <br />' 4.0. FINDINGS <br /> AGE determined ground water flow direction and gradient from the field data collected on 01 <br />' November 2001, the contaminant impact to ground water was assessed from the laboratory data <br /> From field data collected at the SVE remediation system during the fourth quarter 2001, AGE <br />' determined the average TPH-g concentration and the average flow rate and calculated the <br /> approximate mass and volume of hydrocarbons removed <br /> 4 1 GROUND WATER ELEVATION AND GRADIENT <br />' The depths to ground water in wells MW-1,MW-4A, MW-4B, MW-6 and MW-8 were measured <br /> between 20 06 and 21 71 feet below the tops of the well casings Ground water elevations at the site <br /> were calculated to be between 10 54 feet and 12 30 feet below mean sea level, ground water <br /> elevations are depicted in Figure 3 Ground water elevation at the site decreased an average 1 51 feet <br /> between the July 2001 and the November 2001 ground water monitoring events <br /> The general ground water gradient at the site was calculated to be approximately 0 02 ft/ft or less, <br /> or approximately 125 feet per mile, directed towards the south-southwest (Figure 3) <br /> 4 2 LABORATORY RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in water samples collected from wells MW-1, MW-2, MW-4A, MW-4B and <br /> MW-6 at concentrations as high as 46,000 micrograms per liter (µg/1), the highest TPH-g <br /> concentration in first water was detected from MW-2 The laboratory reported the MW-1,MW-2, <br /> MW-4A, MW-4B and MW-6 sample chromatograms contained significant unmodified or weakly <br /> modified gasoline The inferred extent of dissolved TPH-g is depicted in pian view in Figure 4 <br /> Various BTEX compounds were detected in water samples collected from MW-1,MW-2,MW-4A, <br /> MW-413 and MW-6 at concentrations as high as 7,800,ug/l xylene(MW-2), the maximum benzene - <br />' concentration was detected in the sample collected from MW-4B at a concentration of 4,000,ug/l <br /> i <br /> MTBE was detected in water samples collected from MW-4A and MW-4B at concentrations of <br /> 9 lug/1 and 35 µg/1, respectively, DIPE was detected in a water sample collected from MW-1 at a <br /> concentration of 3 4,ug/l No other fuel components were detected by laboratory analysis Previous <br /> and current analytical results of ground water monitoring well samples are summarized in Tables 3 <br /> Advanced GeoEnvironmental,Inc <br />