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. 14 July 1997 AGE-NC Project No 95-0143 Page 2 of 3 Inc , in Pacheco, California (MAI), and 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 decreased an average of 1 98 feet between February 1997 and May 1997 The approximate hydraulic gradient was calculated to be 0 0066 ft/ft with a northerly flow direction, corresponding to gradients measured at the Madison site However, a shallower gradient of 0 0033 ft/ft was measured on the southern corner of the subject property Relative ground water elevation contours for the May 1997 monitoring event are illustrated in Figure 3 32 ANALYTICAL RESULTS OF WATER SAMPLES During the May 1997 monitoring, TPH-g was detected at concentrations of 190,000 parts per billion (ppb, reported as micrograms per liter), 1,200 ppb,4,500 ppb and 35,000 ppb, in samples from MW- 3, MW-6, MW-7 and MW-9, respectively BTE&X were detected in samples from the same wells at concentrations up to 51,000 ppb (toluene in sample from MW-3) MTBE was detected in MW-9 at a concentration of 85 ppb Petroleum hydrocarbons were not detected in the samples collected from MW-10, MW-14,MW-15, MW-16 or MW-17 Free product was not encountered at the site Analytical results of ground water samples 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. SUMMARY/CONCLUSIONS Based upon data collected from the site, AGE has the following summary and conclusions • Petroleum hydrocarbons were not detected in wells MW-10, MW-14, MW-15, MW-16 and MW-17, thereby defining the maximum horizontal extent of impacted ground water The plume of impacted ground water does not appear to be actively migrating Advanced GeoEnvironmental,Inc