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pRELTMINARY REPORT AND TA CLOSURE REPORT Tracy Boulevard Shell 3725 Tracy Bou:eva 1,Tracy,Califurnia Delta Project No.40-89.012 Page 13 On June 4,1490,13 barrcls of sludge and water were pumped from the tank. The tank was then dismantled and removed on June 5, 1990. Appendix I contains analytical results on samples of the sludge. Although the analytical results did not indicate that the sludge was a hazardous material, it was manifested and transported as a hazardous material to a Class I landfill on August 17, 1910. On June 4, 1990,a Delta geologist collected two soil samples from the native material beneath the flow- through tank. The former tank location and sampling points are displayed in Figure 8. The samples where collected with a backhoe at each end of the tank excavation,8 feet below the ground surface. As requested by the County, the samples were shipped to a state-certified analytical laboratory and analyzed for BTEX and TPH as gasoline. Table 10 presents the laboratory analyses results, and Appendix H presents the laboratory data sheets. 4.7 Soil Conditions in Arens Beneath Farmer I'umts Blands On May 7,8,and 9,1990,Delta geologists directed overexcavation work in the eastern portion of the site in an attempt to remove all of the soil containing petroleum hydrocarbons. Figure 9 displays the location of the excavation work. At the end of each work day,verification soil samples were collected in the base and sidewalls of the excavation. The samples were shipped to a state-certified analytical laboratory and analyzed on a 12-hour tush basis for concentrations of BTEX and TPH as gasoline- Excavation work continued the following day based on the laboratory analytical results from the previous day. Excavation work proceeded in the sidewalls until all of the soil containing detectable BTEX concentrations and TPH concentrations greater than 10 ppm had been removed. Excavation work proceeded vertically until all of the soil containing petroleum hydrocarbons had been removed or until the ground water was encountered. A total of nine soil samples were collected on May 7, 1990,rive on May S. 1990,and two on May 9, 1990. Sample locations are shown in Figure 9. Table I I presents the laboratory analyses results,and Appendix H presents the laboratory data sheets. Soil containing petroleum constituents between the surface and approximately 9 feet below the surface(near the water table) has been removed. However, petroleum constituents have been identified in soil at the water table,approximately 14 feet below the surface. Figure 10 displays the soil sampling points where petroleum constituents have been identified at the water table