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i W 18 December 1997 AGE-NC Project No 95-0173 ' Page 6 of 10 3 0. FINDINGS 3 1 QUARTERLY RELATIVE GROUND WATER ELEVATION AND GRADIENT On 16 October 1997, the depths to ground water in wells MW-1 through MW-9, VW-1 and VW-2 ranged between 31 80 and 34 57 feet bsg Between July and October 1997, general ground water ' elevation at the site decreased an average of 2 54 feet Relative ground water elevations, as measured on 16 October 1997, are depicted in Figure 3 In October 1997,the general ground water gradient at the site was calculated to be approximately 0 005 ft/ft or approximately 25 feet per mile and directed in a northeastward direction There has been no significant change of the approximate ground water flow direction at the site since April 1997 32 DISSOLVED OXYGEN MEASUREMENTS On 16 October 1997, dissolved oxygen measurements were recorded while purging wells MW1 liethrough MW9, VW 1 and V W2 Dissolved oxygen measurements ranged from 0 41 mg/l (MW-4) to 3 24 mg/1 (MW-5) Results of dissolved oxygen in ground water samples are summarized in Table No 2 3 3 ANALYTICAL RESULTS OF GROUND WATER SAMPLES During the October and November 1997 ground water sampling events, TPH-g was detected in samples collected from MW1 through MW4, MW6, MW8, MW9, VWI, AW1B and AW213 at ' concentrations as high as 250,000 parts per billion (ppb, reported as micrograms per liter) TPH-d was detected in samples collected from MW1 through MW9, VWI, AW1B and AW213 at concentrations up to 27,000 ppb The laboratory report noted that the sample chromatograms were not consistent with typical diesel patterns BTEX compounds were detected in ground water samples collected from MW1 through MW4, MW6, MW8,MW9, VWI AW1R and AW2B at concentratinnc ac hiph as 52,000 nnb The highest concentration of benzene was encountered from MW4 and V W I at concentrations up to 18,000 ppb MTBE was not detected in any of the ground water samples as analyzed by EPA Method 8020 analysis However, MTBE was detected from MW3, MW4, VWI and AW213 at concentrations as high as 190 ppb utilizing EPA method 8260 TBA and DIPE were detected from AW213 at concentrations of 23 ppb and 3 6 ppb, respectively TAME and ETBE were not detected in the laboratory analysis of any ground water samples Analytical results of selected ground water samples Advanced GeoEnvironmental,Inc