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Site Background Information: Cherokee Truck Stop AGE-NC Project No. 97-0312 Page 4 of 9 piping/dispenser samples at concentrations as high as 1,200 mg/kg and 16,000 mg/kg, respectively. Excavation of approximately 400 cubic yards of hydrocarbon- impacted soil was performed after removal of the USTs. Excavated soil was stockpiled on site. Procedures and findings were summarized in the UST Removal Report - September 1997 prepared by AGE. • November 1997 - On 22 November 1997, the stockpiled soil was spread to a thickness of approximately three feet. On 24 November 1997, a total of 16 samples were collected from the stockpiled soil and analyzed for TPH-g, TPH-d, benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary butyl ether (MTBE). TPH-g and TPH-d were detected in the samples at concentrations as high as 1,500 mg/kg and 4,100 mg/kg, respectively. Stockpile sampling was summarized the AGE's Quarterly Report - December 1997, dated 13 February 1998. • June 1999-Soil borings B14 through B17 and monitoring well UST-6 were installed at the site and soil and grab water samples were collected. The borings were advanced to further define the hydrocarbon-impacted soil plume; UST-6 was installed to delineate the northern extent of hydrocarbon-impacted ground water. Borings B14 through B17 were advanced to a vertical depth of approximately 100 feet below surface grade (bsg); boring UST-6 was drilled to a vertical depth of 75 feet bsg. TPH-g was detected in samples B14-20 and B15-15 at concentrations of 570 mg/kg and 540 mg/kg, respectively. TPH-d was detected in six of the 24 samples analyzed (1314-20, B14-30, B15-15, B15-20, B17-25 and B17-40) at concentrations as high as 13,000 mg/kg(B14-20). Benzene was detected in sample B14-20 at a concentration of 4.1 mg/kg. Toluene, ethylbenzene and xylenes were detected in samples B14-20 and B15-15 at concentrations as high as 9.8 mg/kg. Other petroleum hydrocarbons were not detected in the 24 soil samples analyzed. MTBE was detected by EPA Method 8260 in samples B14-20, B17-25 and B17-40 at concentrations of 0.41 mg/kg, 12 mg/kg and 8.1 mg/kg, respectively.Tert-butanol was detected in sample B14-20 at a concentration of 0.3 mg/kg. Other oxygenates were not detected in these three samples or in sample B15-15. MTBE was detected by EPA Method 8020 in samples B14-30 and B17-50 at concentrations of 0.051 mg/kg and 0.54 mg/kg, respectively. Additionally, grab ground water samples were collected from borings B-14, B-15 and B-17. TPH-g, TPH-d, MTBE and BTEX were detected in each sample. MTBE concentrations ranged from 6.4 pg/I in the sample from B-14 to 9,700 pg/I in the sample from B-17. • September 1999 - Twelve soil borings were advanced at the site to further define the lateral and vertical extent of hydrocarbon-impacted soil. Borings B18 through B29 were advanced to vertical depths between 30 and 70 feet bsg. TPH-g was detected in only one sample (B21-10) at a concentration of 6.7 mg/kg. TPH-d was detected in 11 of the 39 samples analyzed at concentrations as high as 660 mg/kg (1321-10). Benzene was detected in four of the 39 samples at concentrations as high Advanced GeoEnvironmental,Inc.