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• 05 September 2002 AGE-NC Project No. 95-0100 Page 6 of 9 ' 3.7.1. Analytical Results of Soil Samples r TPH-g and/or BTEX compounds were detected in 13 of the 18 soil samples analyzed from the soil ' borings. TPH-g was detected at concentrations as high as 2 1,100 milligrams per kilogram(mg/kg) in soil boring CB2 at a depth of 10 feet bsg. ' TPH-g concentration in soil boring CB 1 decreased with depth from 5,200 mg/kg to 5.4 mg/kg between 10 and 20 feet bsg. TPH-g concentration also decreased with depth in boring CB2 from 21,000 mg/kg to 35 mg/kg between 10 and 20-feet bsg. ' BTE&X were detected at concentrations up to 1,000 mg/kg (xylene) in soil boring CB I at a depth of 10 feet bsg. Xylenes were detected at a concentration of 4,400 mg/kg in soil boring CB2 at a depth of 10 feet bsg. Benzene was detected in one of the soil samples, CB2-25, at a concentration of 0.006 ' mg/kg. MTBE was detected in samples CB 1-45, CB 1-50 and CB2-15 at concentrations as high as 22 mg/kg in sample CB2-15. The analytical results of the soil samples are summarized in Table 3. 3.7.2. Analytical Results of Grab Ground Water Sample TPH-g was not detected in the "grab"water sample collected from boring CB 1. Toluene, l ie ethylbenzene and xylenes were detected at concentrations of 1.3 micrograms per liter(µg/1), 1.7µg/1 and 16 µg/1, respectively. MTBE was also detected in the water sample at concentration of 590 µg/l by EPA Method 8020 and at 790 µg/1 by EPA Method 8260 Modified. The analytical results of the "grab" ground water sample are summarized in Tables 4 and 4A. 3.7.3. Remediation Progress Comparisons of the pre- and post-remediation concentrations for TPH-g and BTE&X compounds are attached in Appendix B. ' Petroleum hydrocarbons were detected in the soil sample analyzed from the boring advanced at the site. The highest concentrations of petroleum hydrocarbons in soil remain at depths of 10 feet and 15 ' feet bsg below the former fuel dispenser area. The reduction of hydrocarbon concentrations ranged between 46 % and 77 % at a depth of 15 feet bsg and approximately 60 % in the soil above 10 feet bsg. ' Benzene was not detected in the samples collected near formers sampling g points of benzene detection. The reduction of benzene concentrations at a depth of 10 feet to 15 feet was virtually 100%, while the estimated reduction of benzene at a depth of 25 feet to 30 feet bsg is approximately 95%. MTBE was detected at a significant concentration(22 mg/kg) in-a soil sample_at a depth of 15 feet bsg; and - ---atlowerconcentrations 0.65 rn g/kg and 0.097 mg/kg) in soil above or near the ground water table. Advanced GeoEnvironmental,inc. 1