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Section 3 BACKGROUND PREVIOUS ACTIVITIES The locations of all previous soil borings and soil samples taken at the station are shown on the Site Plan, Figure 2. Analytical results of soil and water samples tested from the previous studies are summarized in Table 1 and the laboratory data sheets are included as Appendix A. In the spring of 1988, during the construction of a foundation pad for a new reboiler unit, PG&E personnel reported the presence of hydrocarbon odors in excavated soil removed from around the reboiler water collection sump and associated discharge line. The presence of these hydrocarbons in the subsurface soils adjacent to the sump and discharge line suggests that small quantities of petroleum hydrocarbons and glycol were inadvertently removed with the water from the gas during the dehydration process. PG&E subsequently removed approximately 100 cubic yards of soil from around the affected area. This material was stockpiled on site for later disposal or treatment. On March 11, 1988, at the request of PG&E, The Twining Laboratories, Inc. conducted a preliminary survey of the of soil and the reboiler water discharge line at the site. The survey consisted of taking and analyzing three soil samples and one discharge water sample. The soil samples (S-1 through S-3) were grab samples taken from the excavation in the area of the discharge line. A sample (S-4) was taken of the water in the discharge line. The soil samples and water sample were analyzed by the Twining Laboratories for total petroleum hydrearbons (TPH), and benzene, toluene, and xylenes (BTX) by EPA Methods 8015 and 8020, respectively. In addition, one of the S-4 water samples was transported to PG&E's chemical laboratory in San Ramon and analyzed for glycol compounds. The results of these analyses indicated that TPH were present in all four samples (Si concentration was very low). The only samples containing BTX were S2 and S3. Glycol compounds were detected in the S4 water sample in concentrations up to 11,110 ppm. On May 19, 1988, Groundwater Technology Environmental Laboratories, Inc. (GTEL) was requested by PG&E to conduct a follow-up soil survey in the vicinity of the reboiler discharge line. The purpose of this investigation was to evaluate the subsurface soil conditions and feasibility for performing in-situ bioremediation of the affected soils. Soil samples were taken from 3 exploratory borings located around the discharge line. 462891/42/PPU26 3-1