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T1& b 3.3.2 Pump Island Excavation During June 2004, soil sampling was conducted at the former pump island and associated fuel lines to determine if releases of petroleum hydrocarbons had occurred. Analyses indicated that releases had occurred, and soil was subsequently excavated using an excavator. Sidewall confirmation samples were collected on the north,west, and south walls, and in the bottom of the excavation. Analytical results for samples from previous borings CSB-4 and CSB-5 contained no or low petroleum hydrocarbon concentrations, which provided excavation limits for the northwest and southwest portions of the excavation. A sidewall sample was not collected from the east wall as this was a ramped area required for OSHA regulations. Elevated concentrations of TPH-g at 2,300 milligrams per kilograms (mg/kg), and TPH d at 700 mg/kg,were detected in the confirmation sample CPT-EXC-BT-19,which was collected from the deepest part of the excavation(19-feet deep)where the bottom intersected the water table. Because this was the maximum excavation depth possible without shoring the excavation, impacted soil below 19 feet was not removed. The pump island excavation and confirmation sample locations are illustrated in Figure 2, and analytical results are presented in Table 3. The final excavation dimensions were approximately 25 feet wide by 22 feet long with an average depth of 10 feet(Treadwell& Rollo,2004b). 4.0 PROPOSED REMEDIAL WORK 4.1 Summary of Identified Contamination The data indicate that concentrations of petroleum hydrocarbons are likely present in soil and groundwater below sample location CPT-EXC-BT-19. Sample CPT-EXC-BT-19 is located at 19 feet bgs,approximately 10 feet south of the West Fremont Street sidewalk, and 5 feet south of the limits of the former shored excavation. As described in Section 3.1,rising groundwater at the Site has resulted in a smear zone of soil with TPRg concentrations to at least 10 feet below the water table. Soil at boring CSB-2, located approximately 15 feet north of sample location CPT-EXC-BT-19, had TPH g concentrations greater than 1,000 mg/kg extending to 30.5 feet 4 25970122.DGD 14 February 2005