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Mr. Ray Von Flue San Joaquin County Environmental Health Department January 23,2003 Page 2 Soil Sampling Dispenser Islands and Product Piping On August 15, 2002, the dispenser islands and the associated product piping were excavated and removed. After the removal, Stratus Environmental collected one soil sample from below each of the four product dispensers (designated D-1-4 through D-44), and two soil samples from beneath the product lines (designated L-1-4 through L-2-3.5). Sample locations are shown on Figure 2. Samples were collected at depths of approximately 4 feet below ground surface (bgs) with a slide hammer. The slide hammer was thoroughly decontaminated between sample locations. Field and laboratory procedures are presented as Attachment B. Soil Sampling-USTs On August 20, 2002, URS collected a total of 12 soil samples (designated PB-1-N-16' through PB-12- S-17.5') from the bottom of the tank pit at the north, center, and south portions of each former UST location (Figure 2). The bottom of the tank pit was 16 to 18 feet bgs. Soil samples were collected by pushing a brass tube into a fresh backhoe bucket of soil collected from the locations shown on Figure 2. Soil Sample Analysis and Results Soil samples were analyzed for total petroleum hydrocarbons calculated as gasoline (TPHg) by EPA Method 8015; benzene, toluene, ethylbenzene, total xylenes (BTEX), and methyl tert-butyl ether (MtBE)by EPA Method 8021; and fuel oxygenates (tert butyl alcohol [TBA],MtBE,di-isopropyl ether [DIPE], tertiary amyl methyl ether (TAME), ethyl tertiary butyl ether ETBE, ethylene dibromide [EDB],and 1,2-dichloroethane [1,2-DCA])by EPA Method 8260B. No analytes were detected above reporting limits in the six soil samples collected from below the dispenser islands and the product lines. TPHg, ethylbenzene, and xylenes were detected at concentrations of 120 milligrams per kilogram (mg/kg), 0.44 mg/kg, and 0.92 mg/kg, respectively, in sample PB-10-N collected from the bottom of the northeast corner of the tank pit. MtBE was detected in 9 of 12 samples collected from the bottom of the tank pit with a maximum concentration of 0.41 mg/kg reported in PB-5-M. TBA was detected in two of the soil samples from the tank pit up to 6.8 mg/kg in PB-3-S. The results of soil samples collected from the UST excavation are presented in Table 1.Laboratory analytical reports and chain-of-custody documentation is presented as Attachment C. Remedial Activities-Over-excavation On August 23, 2002, approximately 45 tons of soil were removed from the bottom of the northeastern corner of the tank pit. The area (shown on Figure 2) was over-excavated to a depth of approximately 19 feet bgs. Over-excavation activities were conducted under the supervision of SJCEHD. Most of the soil encountered during the excavation was green-gray in color and had a strong odor of gasoline. Groundwater was not encountered during over-excavation activities. One soil sample was collected at approximately 18 feet bgs from each of the sidewalls of the over- excavation (SW-N-18.5, SW-W-18', SW-E-18', and SW-S-18.5'). An additional soil sample (PB-M- 19.5) was collected from the bottom of the over-excavation. Over-excavation soil sample locations are shown on Figure 3.Field notes are included as Attachment D. K:1J5 BP ARCO\00760\UST Removal\UST removal 2nd report.doe