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F r ' 02 Augusf 2000 AGE-NC Project No 95-0121 Page 4 of 7 ' were measured between 13 86 and 14 97 feet below the tops of well casings, ground water elevations were calculated to be between 7 51 feet and 8 08 feet below mean sea level (Table 1) Ground water elevation at the site increased an average 2 11 feet between the January 2000 and April 2000 ground water monitoring events The ground water elevation data for the April 2000 ground water monitonng event is depicted in Figure 3 ' Ground water flow direction at the site was inferred to be toward the northeast at a gradient of 0 004 ft/ft or less, or approximately 21 feet per mile (Figure 3) ' 4 2 LABORATORY RESULTS OF GROUND WATER SAMPLES ' ' TPH-g was detected in ground water samples collected from wells MW-1, MW-2, MW-3, MW-4 and MW-7 at concentrations as high as 37,000,ug/l (MW-3) TPH-d was detected in water samples collected from wells MW-1 through MW-7 at concentrations as high as 2,600 4g/l, however, the ' laboratory reported the diesel chromatograms from each sample chromatogram as having significant non-diesel patterns (lighter range gasoline compounds) ' • BTEX compounds were detected in ground water samples collected from wells MW-1, MW-2, MW-3, MW-4, MW-6, and MW-7 at concentrations as high as 8,600,Zg/l (benzene, MW-2) ' MTBE was detected in the ground water samples collected from wells MW-2 and MW-5 at concentrations of 650 and 6 3 4g/1 respectively Previous and current analytical results of ground ' water monitoring well samples are summanzed in Tables 2 and 3 The laboratory reports (Castle Analytical Laboratory Reference No 2972)and chain'of-custody forms are presented in Appendix C ' ' 43 RESULTS OFIN-SITU AIR SPARGING AND SOIL VAPOR EXTRACTION _ F ' Between 01 April 2000 and 30 June 2000, the SVE and IAS remediation systems were operational for 2,184 hours (Table 5) During the operational period, SVE inlet flow rates ranged from 39 to 48 cubic feet per minute (cfm), differential pressures ranged between 0 5 and 0 75 inches of water, and ' induced vacuum between 15 and greater than 25 inches of water Utilizing a photo ionization meter (PID), hydrocarbon concentrations were measured between 8 and 32 parts per million (ppm) at the SVE inlet, however a general concentration trend was not established from the PID field measurements Field measurements are summarized-in Table 5 , Advanced CeoEnwronmental,Inc I 5