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T � ' 19 March 1999 AGE-NC Project No. 98-0471 Page 3 of 12 2.5. PREVIOUS INVESTIGATIONS At the request of Herum, Crabtree et al,AGE conducted a limited soil excavation assessment at the site. A total of nine trenches were established for sampling on the site and the findings are summarized below. The work performed on the site is detailed in the Excavation and Sampling Report, dated 10 August 1998, prepared by AGE. • In July 1998, trenching was performed at the site, in the two areas of concern, to assess whether or not hydrocarbon releases had impacted soil and ground water. The approximate trenching limits are depicted on Figure 2. The analytical results of soil and water samples described below are summarized in Table 1. • The soil profile generally consists of peat from the surface to approximately five feet bsg and sandy clay from five feet bsg to eight feet bsg. • Soil and ground water samples collected from the gasoline AST area trench T1 had the greatest concentration of total petroleum as gasoline(and benzene, as well as methyl tertiary butyl ether(MTBE). TPH-g,benzene, TPH-d and TPH-mo were detected at concentrations up to 19,000 milligram per kilogram (mg/kg), 180 mg/kg, 10,000 mg/kg, 7,800 mg/kg, respectively. • Impacted soils are limited to above a depth of eight feet bsg, based on analytical data of soil samples collected from trench T1. Soil data from samples collected from trenches established surrounding Trench T1 contained low concentrations of TPH-g and BTEX compounds. Soil impacted with hydrocarbons was limited by trenches established 20 feet north (T5), 45 feet east (T6) and 40 feet ea2t�T7) of the former gasoline AST. Hydrocarbon impacted soil is depicted in Figure 3. • Water samples collected from trenches established forty feet west(T7) and 90 feet east(T8) of the gasoline AST had little to no detectable concentrations of dissolved contaminants. Water samples collected from trench T5, 30 feet north of the gasoline AST had low concentrations of benzene and no detectable MTBE. The grab water sample concentrations are depicted on Figure 4. • Based on the laboratory analysis of the samples collected the extent of petroleum hydrocarbon impacts to soil and ground water has been delineated. • As a result of the trenching 52.5 tons soil were removed from the site. This volume soil contained an estimated 90 gallons of petroleum (Appendix A). Advanced GeoEnvironmental,Inc.