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*awl r.► 21 November 1996 AGE-NC Project No. 95-0106 Page 2 of 4 were transported in a chilled container, under ice, to MAI and analyzed for TPH-g, total petroleum hydrocarbons quantified as gas(TPH-g),BTE&X and methyl-tert-butyl ether(MTBE)in accordance with EPA method 5030/8015m, 602 and 602, respectively. 3.0. FINDINGS 3.1. GROUND WATER ELEVATION AND GRADIENT The ground water elevation in each well was calculated by subtracting the depth to ground water from the surveyed casing elevation (Table 3). Monitoring well casing elevations were surveyed relative to monitoring well MW-1. Ground water gradient on 05 November 1996 was calculated to be an average of 0.002 ft/ft(10.4 feet per mile)directed N 17°W. The relative ground water elevation at the site is illustrated in Figure 3 - Relative Ground Water Elevation. 3.2. LABORATORY RESULTS OF GROUND WATER SAMPLES The highest concentrations of hydrocarbons were detected in wells MW-1 and MW-4, located down- gradient (north) of the former UST excavation; TPH-g was detected at concentrations as high as 4,100 micrograms per liter: ,ug/l (part per billion: ppb, reported as micrograms per liter). Benzene was detected at concentrations of 11 ppb and 260 ppb in MW-1 and MW-4, respectively. The maximum toluene concentration detected was 35 ppb, encountered in MW-4. The maximum ethylbenzene and total xylenes concentrations of 140 ppb and 270 ppb, respectively, were encountered in MW-4.Neither TPH-g nor BTE&X were detected in the ground water samples from MW-2 and MW-3. MTBE was detected in samples collected from wells MW-1 and MW-4 at concentrations of 4.6 ppb and 45 ppb, respectively. Analytical results of around water samples are summarized on Table 2. All analytes detected in the ground water samples had declined by approximately one order of magnitude since the first round of sampling in July 1996 The laboratory report (MAI Laboratory ID 70993 through 70996) and chain-of-custody are in Appendix C.