SITE INFORMATION AND CORRESPONDENCE

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Ms. Mary Serra August 19,2002 Page 3 petroleum hydrocarbons in soil and groundwater appears to be limited to a relatively small area. Removal of TPH-containing soil above and below the water table is expected to reduce TPH concentrations in groundwater. Groundwater monitoring will continue after the excavation and if concentrations are reduced,no further action may be appropriate. Soil Remedial Activities The soil excavation includes the following(in the order in which they will be implemented in the field): Demolition and Removal The two underground utility lines located within the excavation limits,which are associated with the existing sump and are currently inactive (See Figure 2),will be abandoned and capped. The existing sump will also be removed. Disposal of the utility lines and sump will be in accordance with applicable regulations and PG&E protocols. Well Abandonment Four existing monitoring wells and one piezometer will be abandoned in accordance with San Joaquin County requirements prior to commencing excavation. The four monitoring wells are: MW-2,MW-5,MW-6,MW-7 and the piezometer is PZ-2. The wells are located within the proposed excavation limits. Soil Excavation and Disposal The proposed excavation is located in the area of known TPH-containing soil and groundwater adjacent to the former reboiler(Figure 2). Results from previous investigations indicate TPH-d and TPH-k concentrations in this area at depths between 5 and 12 feet bgs. The excavation footprint is irregular and covers approximately 510 square feet. The depth of the excavation is projected to be a minimum of 13.5 ft bgs. Approximately 700 cubic yards of soil will be removed(including anticipated over-excavation to facilitate side wall slope stability). Excavation activities will be conducted in accordance with applicable excavation and/or grading permits from San Joaquin County. The actual excavation limits will be determined based on visual observations and other field indicators (e.g.staining and odor). The east side excavation limit is based on receiving approval for offsite access. Due to the depth of the excavation,sloping requirements will be enacted,which will result in over-excavation. If offsite approval is not granted,shoring will be used to prevent extending the east wall of the excavation off-site. Verification sampling will be conducted along the excavation limits to document preliminary remedial cleanup goals. Excavation will proceed as needed unless constrained by existing underground utilities or other infrastructure that may pose safety hazards or by off-site access constraints. Excavated spoils will be transported and disposed in accordance with all applicable regulations and in an environmentally safe manner. Soil will be transported to Forward Landfill in Stockton,CA for disposal. All trucks will be lined with visqueen prior to loading and will the loads will be tarped after final loadout. A manifest for non-hazardous soil will be prepared for each truckload and handed to appropriate parties. Manifests will be kept on-site during construction activities and will be included with project files at the conclusion of the removal action.