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04 October 2005 • AGE-NC Project No 98-0432 Page 3 of 6 The soil left in place was impacted by low to moderate concentrations of total petroleum hydrocarbons quantified as diesel (TPH-d) r The analytical data Indicated significant concentrations of TPH-d dissolved in the ground water Results of the September 1998 investigation were reported in the AGE-prepared Preliminary Investigation and Evaluation Report(PIER), dated 09 March 1999 Analytical results of soil samples are presented in Table 2,analytical results for the grab ground water sample are presented in Table 3 24 PREVIOUS SITE ASSESSMENTS On 03 December 1998, six soil probe borings (B 1 through 136) were advanced at the site to assess the lateral and vertical extent of petroleum-impacted soil and ground water (Figure 2) The oxygenated fuel additive methyl tertiary-butyl ether(MTBE)was detected in both grab ground water samples analyzed at concentrations as high as 760 micrograms per liter(µg11) No other fuel additives were detected in the analysis of the soil or grab ground water samples Analytical results for soil and grab ground water samples are presented in Tables 2 and 3,respectively On 12 and 13 January 2000, Monitoring wells MW-1, MW-2, MW-3, and MW-4 were installed at the site with screen Intervals between 10 feet and 30 feet bsg Total petroleum hydrocarbons quantified as gasoline (TPH-g), TPH-d, and benzene, toluene, ethylbenzene, and total xylenes (BTEX)were not detected at or above laboratory reporting limits in the nine soil samples analyzed from wells MW-1, MW-2, and MW-3 However, MTBE was detected In eight of the nine soil samples at concentrations ranging from 0 110 milligrams per kilogram (mg/kg) to 2 58 mg/kg (MW 1-20) Analytical results of soil samples collected from the January 2000 well installations are presented in Table 2 , On 12 October 2000, three soil probe borings (137 through 139) were advanced at the site to a total depth of 50 feet bsg Soil samples were collected at 5-foot intervals, beginning at a depth of 30 feet bsg MTBE was detected in two of the soil samples analyzed by EPA Method 8020 and in four soil samples analyzed by EPA Method 8260B The detected MTBE concentrations ranged from 0 0051mg/kg (138-50) to 0 052 mg/kg (138-30) MTBE was detected in the grab water sample collected from boring B8 at 50 feet bsg at a concentration of 29 µg/1 by EPA Method 8260 MTBE was not detected in the other grab ground water samples Analytical results of soil and grab ground water samples are presented in Tables 2 and 3, respectively On 11 December 2000, ground watci monitoring wells MW-5 and MVV-!i, screened from 10 feet to 30 feet bsg, were installed on-site to assess the lateral extent of MTBE-impacted ground water Soil samples were not collected during the well Installations • On 20 December 2000, ground water extraction well EW-1 was installed at the site for the Advanced GeoEnvnronmentai,Inc