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i 12 October 2000 • AGE-NC Project No 99-0637 Page 6of7 44 ANALYTICAL RESULTS OF GROUND WATER SAMPLES Grab ground water samples were collected from borings B 1 through B3, and were submitted to a DHS-certified laboratory for analysis as noted above TPH-g was detected in the ground water samples collected from B 1 and B2 at concentrations of 110 micrograms per liter (µg11) and 1,200 4g11, respectively TPH-d was not detected above laboratory reporting limits in the ground water samples collected from B 1 through B3 The only BTEX compound detected above laboratory reporting limits in the ground water sample analysis was benzene Benzene was detected in the ground water samples collected from boring B 1, B2 and B3 at concentrations of 28 µgll, 310µg/1 and 0 53 µg/1, respectively Dissolved MTBE was detected in the same ground water samples at concentrations of 430µg/l, 10,000 ug/l and 67 4g/1, respectively TBA was detected in the ground water sample collected from B 1 at a concentration of 400µg/1 INo other fuel oxygenated compounds were detected above laboratory reporting limits during the laboratory analysis of the ground water samples Analytical results of ground water samples are � . summarized in Table 2 The laboratory report(Alpha Analytical Inc Lab Order No A00032103)and chain-of-custody forms are included in Appendix B I5.0. SUMMARY AND CONCLUSIONS IBased upon data collected on 20 March 2000, AGE concludes the following • First encountered ground water is at approximately 20 feet bsg IMTBE was detected in the 20-foot soil sample collected from probe boring B2 at a concentration of 16 mg/kg No other analytes were detected above laboratory reporting limits in the soil sample analysis • Ground water is impacted on the site by TPH-g, benzene and MTBE • Laboratory and field data suggest that benzene-and MTBE-impacted ground water is present in the area enclosed by B 1, B2 and B3, and extends laterally past the borings Figures 3 and 4 show possible distribution models for dissolved benzene and MTBE • Laboratory and field data suggest that TPH-g-impacted ground water is present in the area between B i and B2, and extends laterally past the borings I The State of California drinking water standards, adopted under the Safe Drinking Water Act, have established maximum contaminant levels (MCLS) for benzene, toluene, ethylbenzene and xylenes at 1 ug/l, 150 µg/l, 700 µg/1 and 1,750 µg/l, respectively Advanced GeoEnvironmentai,Inc I