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I 28 December 2001 • AGE-NC Project No 98-0511 Page 3 of 4 BTEX compounds were detected in MW-1 at concentrations of43 pg/l benzene, 19µg/1 toluene, 120 gg/1 ethylbenzene and 210 µg/1 total xylenes, Benzene and toluene were detected In MW-5 at concentrations of 9 3 pg/l and 3 3 µg/1, respectively Benzene (0 59 pLg/1) was also detected in the sample from MW-3 MTBE was detected in the ground water samples collected from MW-1 MW-3 and MW-5 at I concentrations of 3 4 µg/1, 39 gg/l and 160 µg/1 respectively No other fuel oxygenated compounds were detected at concentrations above laboratory reporting limits ' Analytical results of ground water samples are summarized on Table 2 Maps showing the lateral distribution of TPH-g,benzene and MTBE are provided in Figures 3 and 4 Copies of the laboratory report (MAT Laboratory ID 79468-79475) and chain-of-custody forms are in Appendix B I 4 0. SUMMARY AND CONCLUSIONS Based upon data collected from the site, AGE concludes the following • The ground water gradient was very gentle,calculated to range from less than 0 0001 ft/ft to 0 0009 ft/ft,the ground water flow direction appeared to be generally northwestward on the site, varying from nearly west to north-northeast 4 Samples from MW-2, MW-4, MW-6, MW-7 and MW-8 had less than detectable concentrations of all analytes • The MTBE concentrations in the ground water samples collected from MW-3 (39 µg/l) and MW-5 (160µg/1)are above California's Primary Maximum Contaminant Level(13 µg11)for MTBE ' e The plume of impacted ground waxen'has been delineated toward the south,west,southeast, and north, but has not been constrained toward the northwest or east to northeast I5.0 RECOMMENDATIONS Based upon data collected from the site, AGE recommends continued ground water monitoring at the site AGE recently advanced three soil borings at the site to define the vertical as well as the northwestern and eastern lateral extent of the contaminated ground water plume, the report for this investigation is in preparation I Advanced GeoEnvironmental,Inc I