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Analysis of the eight soil samples collected from the sidewall of the excavation detected petroleum hydrocarbons and BTEX constituents in three of the samples at concentrations of up to 53 mg/kg TPH in the gasoline range, 67 mg/kg TPH-D,440 mg/kg TPH-MO, and 0.065 mg/kg ethylbenzene. Analysis of the composite of the stockpiled soil samples detected up to 12 mg/kg TPH-G, 510 mg/kg TPH-MO, and 0.006 mg/kg toluene. Based on the results of the laboratory analysis, the stockpiled soil was used as backfill in the excavation. A work plan for additional soil and groundwater sampling was prepared in February 2002 at the request of PG&E to assess the extent of residual petroleum hydrocarbons and BTEX constituents in soil as well as dissolved-phase hydrocarbons in the groundwater,if any. 2.0 FIELD PROCEDURES After receipt of regulatory approval of the work plan and before performing field activities, a drilling permit was obtained from the San Joaquin County Environmental Health Department (SJCEHD). A copy of the permit is included in Appendix A. 2.1 Soil Boring On June 27 and 28,2002,seven soil borings, SB-7 through SB-13,were drilled to depths of approximately 14 feet using 4-inch-diameter hand augers at the locations shown on Figure 3. To prevent cross-contamination, all drilling equipment that may be in contact with potentially contaminated material was washed using a phosphate-free detergent followed by tap water and deionized water rinses between each use. Decontamination fluids were transferred into a tank truck for disposal at an appropriate disposal/recycling facility. Soil samples were collected using hand sampler lined with stainless steel tubes at three, six,and nine feet below grade,except in Boring SB-13,which was drilled at the location of the former excavation. As such,no soil sample of the backfill material was collected at 3 feet below grade in Boring SB-13. A slide hammer was used to advance the sampler to approximately six inches into the undisturbed soil. Soil sampling was performed following the procedures described in Appendix B and the soil samples were described in general accordance with the Unified Soils Classification System,including color,moisture, density and consistency. The soil boring logs prepared for SB-7 through SB-13 are included in Appendix C. After retrieval from the boring, the sampler was opened,the sample tubes were removed,and a soil sample was selected for chemical analysis. The sample was retained within the stainless steel tube, and both ends were immediately covered with Teflon sheeting and polyurethane caps. The caps were sealed with tape and labeled with the following information: Alisto's project number,boring number,sample depth interval,sampler's initials, and date of collection. The sample was immediately placed in a waterproof plastic bag and stored in a cooler maintained at 4oF. Possession of the samples was documented from the field to a state-certified analytical laboratory by using a chain of custody form. 2.2 Temporary Well Installation Soil Borings SB-7 through SB-13 were converted into temporary wells in accordance with the procedures described in Appendix B. During drilling and soil sampling, groundwater was encountered in each boring at approximately 10 feet below grade. After collection of soil f.\02\U1211\211-15\reportdoc 2 NINO