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1 ' 21 January 1999 AGE-NC Project No 98-0450 Page 5 of 8 ' 30 FINDINGS 31 STRATIGRAPHY tSilty clay was generally encountered ed from a depth of approximately 5 feet to 30 feet or 40 feet bsg across the site Light colored sands were encountered at a depth of 30 feet bsg in the former dispenser area and at 40 feet bsg in the former UST area The sand bodies thickness increased as viewed from the south to the north under the former UST ' Silty clay was encountered at a depth of 45 feet bsg in the dispenser area(boring SB7)and silty clay was not encountered until a depth of 55 feet bsg under the former UST excavation Silty clay was ' only encountered in the soil samples colleted north of the site Soil borings are depicted in Appendix A A stratigraphic cross section of soils at the site is depicted in Figure 3 ' Based upon soil samples submitted for geotechnical analysis, fine sand encountered below approximately 30 to 35 feet bsg have a permeability of 2X10 5 cm/sec and an average porosity of 40% The total percentage of organics calculated from the soil sample analyzed was 133% The soil material laboratory report (Cooper Testing Laboratory report dated 11 November 1998) and chain- of-custody form are included in Appendix D 32 HYDROCARBON-IMPACTED SOIL ' • TPH-g was detected in soil boring SB 1, located directly north of the former UST excavation, at a depth of 15 feet bsg at 14 milligrams per kilogram (mg/kg) BTEX compounds were ' detected in the same soil sample at concentrations of 0 066 mg/kg, 0 4 mg/kg, 0 28 mg/kg and 2 2 mg/kg, respectively • TPH-g was not detected in soil borings S132 nor SB3 BTEX compounds were detected in ' one soil sample from SB2, from a depth of 35 feet bsg at concentrations of 0 012 mg/kg benzene, 0 041 mg/kg toluene, 0 005 mg/kg ethyl-benzene and 0 043 mg/kg total xylene ' BTEX compounds were not detected in the analyzed soil samples from SB3 or any of the other analyzed soil samples collected from soil boring SB2 • TPH-g and BTEX compounds were detected in soil samples from boring SB4 from depths ' of 15 feet bsg to depths of 50 feet bsg Benzene was detected in soil boring SB4 from depths - -—of 15 feet bsg to depths of 30 feet bsg TPH-g was detected at a maximum concentration in this soil boring at 9,600 mg/kg in sample SB4-15 Benzene was detected in the same soil sample at 24 mg/kg • TPH-g and BTEX compounds were detected in soil boring SBS from depths of 15 feet bsg AdiancedGeoEn,,iron mental,Inc