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` 09 August.2000. • AGE-NC Project No. 95-0106 ; Page 2 of 10' 2.3. EXCAVATION OF UNDERGROUND STORAGE TANK AREA •The former UST area was excavated. in 24:August;1995 to remove impacted soil. Excavation procedures were supervised by a representative of AGE. Soil-was excavated to a depth of 12.feet' below surface grade (bsg). Approximately 100 cubic yards of impacted soil were removed from the former UST area. The.approximate limits of the August 1995 excavation'are-indicated on Figure 2.' I •,TPH-g was detected in the soil sample collected at a depth of 8 feet bsg from the sidewall of the excavation at concentrations as high as 5,800 mg/kg and benzene was detected in the samples at a' maximum concentrations of54 mg/kg. Petroleum hydrocarbons were not detected in soil samples collected from the-floor of the excavation at a depth of 12 feet bsg. TPH-g was detected in stockpile soil samples at a concentration of 440 rng/kg and volatile aromatic compounds benzene, toluene, ethylbenzene and total xylenes (BTEX) were detected at bo icentrations of I-I mg/kg, 12 mg/kg, 8.1 I mg/kg and 40 mg/kg, respectively.Laboratory results of excavation wall and floor soil samples are' included in Table 1. The excavated soil was stockpiled adjacent to the excavation on plastic sheeting. On 09 October 1996, approximately 100 cubic yards of stockpiled soil were transported to Forward iIncorporated, a Class II landfill located in Manteca, California: Soil was loaded into transport vehicles by Stokley Construction of Tracy,California and hauled to Forward by Bob Evans Trucking of Manteca, California. The disposal of the soils was summarized in the Quarterly Report prepared by AGE,elated 21 November 1996. 2.3• . ' INITIAL SOIL AND GROUND WATER INVESTIGATION ' I Six-soil 'robe borings were advan p g ced at the site on 20.December 1996. Soil and water samples were , collected-at discrete depth intervals'from the majority of the probe borings. Figure 2 depicts-the Ilocations of the probe•borings. 'TPH-9 was detected in three of the soil,samples analyzed at concentrations as high as 2,800'mg/kg (P3-6).'BTEX compounds were detected in the same three samples at concentrations as high as 93 mg/kg (total xylene, P 1=6), the maximum benzene concentration detected was 2.8 mg/kg (P 1 Table 1 summarizes the soil samples collected.from the.probe borings the site. TPH-g was detected in grab water samples at concentrations as.high ,as 210,000 mg/l.. BTEX I compounds were also detected in,four of five grab ground water samples at concentrations as high as 3 5,000 mg/l (toluene P6), the maximum benzene concentration'detected was 12,000 mg/l (P6): Analytical results of grab water samples are summarized on Table,2. The installation of the soil Iprobe borings was,summarized•in the PIER prepared by AGE, dated 10 September 1996: ' Advanced GeoEnvkonmental,Inc.