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.,,� 11 . Site Background Information: Cherokee Truck Stop AGE NC Project No. 97-0312 Page 2ofII On 18 September 1998, six product USTs were removed from the site. A total of nine UST soil samples and thirteen piping/dispenser soil samples were collected and analyzed. Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d)were detected in the samples collected beneath the USTs at concentrations as high as 2,500 milligrams per kilogram(mg/kg)and 32,000 mg/kg, respectively. TPH-g and TPH-d were detected in piping/dispenser samples at concentrations as high as 1,200 mg/kg and 16,000 mg/kg,respectively.Excavation of approximately 400 cubic yards ofhydrocarbon-impacted soil was performed after removal of the USTs.Excavated soil was stockpiled on site.On 16 March 1998,approximately 180 cubic yards of impacted soil was disposed;the remaining clean soil was used as backfill. PREVIOUS SITE INVESTIGATIONS Site assessment activities summarized below were originally reported in quarterly reports prepared by Environmental Science&Engingeering,Inc. (ESE)between June 1990 and February 1997 and by AGE between March 1997 and May 2001.A list ofreports referenced in preparing this summary was presented in Appendix A of the AGE-prepared Problem Assessment Report, dated 16 August 2001. The following is a summary of significant assessment activities conducted to date at the Cherokee Truck Stop site: • May 1990 - Review of EHD files for the site indicated fourteen soil borings (B 1 through B 13,HA-1)were advanced near the UST,piping and dispenser areas to assess the lateral and vertical extent of impacted soil. Petroleum hydrocarbon compounds were detected in 15 of the 20 samples collected from the borings. Total petroleum hydrocarbons quantified as gasoline (TPH-g) and diesel (TPH-d) were detected at concentrations as high as 5,800 milligrams per kilogram(mg/kg)and 12,000 mg/kg,respectively. Petroleum hydrocarbons in soil were found to extend to a depth approximately 50 feet below surface grade(bsg)near the fueling island location. Soil boring locations are depicted on Figure 2. • September/October 1990-One ground water monitoring well(UST-1)was installed on-site to a depth of approximately 102 feet bsg to determine if petroleum hydrocarbons had impacted ground water. The screen of UST-1 was installed overlapping two coarse-grained intervals and may provide a vertical pathway for migration of impacted ground water. Laboratory analysis of soil samples collected from the UST-1 boring contained detectable concentrations of petroleum hydrocarbon compounds to a depth of at least 85 feet bsg. Laboratory analysis of the initial ground water sample collected from UST-1 also indicated the presence of hydrocarbons. TPH-g,TPH-d and benzene were detected at concentrations of 330 micrograms per liter(µg/1), 880µg/1 and 4.5 µg/l,respectively. • September/December 1992-Ground water monitoring was performed during the third and fourth quarter of 1992 at the site. High concentrations of petroleum hydrocarbons were Advanced GeoEnviron mental,Inc.