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.r n • 28 March 1997 AGE-NC Project No 95-0143 Page 2 of 3 samples were transported under chain-of-custody in a chilled container to McCampbell Analytical, Inc , in Pacheco, California(MAI), and were analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-g), and for volatile aromatic compounds (benzene, toluene, ethylbenzene and xylenes BTE&X) with methyl tertiary-butyl ether(MTBE) in accordance with EPA methods 5030 and 602, respectively 3 0. FINDINGS 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT The relative elevation of ground water in each well was calculated by subtracting the depth to water from the surveyed casing elevation (Table 1) Ground water elevation increased an average of 4 88 feet between November 1996 and February 1997 The approximate gradient was calculated to be 0 0071 ft/ft north of the site, corresponding to gradients measured at the Madison site However, a shallower gradient of 0 0025 ft/ft was measured on the southern corner of the subject property The calculated gradients are steeper than those measured during previous monitoring events The flow direction was generally toward the north to northeast Relative ground water elevation contours for the February 1997 monitoring event are illustrated as Figures 3 32 ANALYTICAL RESULTS OF WATER SAMPLES TPH-g was detected at concentrations of 170,000 parts per billion(ppb, reported as micrograms per liter), 830 ppb, 6,700 ppb and 23,000 ppb, in samples from MW-3, MW-6, MW-7 and MW-9, respectively, during the February 1997 monitoring BTE&X were detected in the same wells at concentrations as high as 37,000 ppb (toluene, MW-3) Petroleum hydrocarbons were not detected in the samples collected from MW-10, MW-14, MW-15, MW-16 or MW-17 MTBE was not detected in any samples collected during the February 1997 monitoring event Free product was not encountered at the site Analytical results are summarized on Table 2 The laboratory report (MAI Laboratory I D Nos 73500 - 73508) and chain-of-custody forms are included in Appendix B 4.0. CONCLUSIONS & RECOMMENDATIONS 41 CONCLUSIONS Based upon data collected from the site, AGE has the following conclusions • Petroleum hydrocarbons were not detected in wells MW-1 W-14 - ' Y 0, M , MW 15, MW-16 and