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T�N1C CL09URF�_EPORT 7910 Lo►ier 9aieraenento Bond atoctcton,CaEifarnin Delta-Project NO.40-88.147 Page b A Delta representative was present during the excavation of the underground storage tanks to ensure all soils being excavated were contained on site. Samples of the backfill material were noticeably �0 discolored and had a moderate petroleum odor. 1'$ 4 F0rmer Tank_l:xcaratia�Sart1 lu a 9 A total of eight soil samples were taken from approximately 2 feet below the bottom of the farmer tank excavation at the request of San Soaquin County,Environmental Health Department. Th--soil samples were analyzed for presence of the following constituents: BTX, TPH, EDB, and organic lead. A summary of the chemical analysis is presented in Table 2. Soil sample identification and locations are shown in Figure 2, and laboratory data'sheets are presented in Appendix A. Concentrations of TPH ranged from nondetected in samples T-1, T-2,T-3, and T-4; to 4,880 ppm in T-5;4,790 ppm in T-6; 1,500 ppm in T-7•and 120 PPm in T-8. i On January 20, 1989,the excavation was backfilled following verbal approval from the San Joaquin County,Environmental Health Department,with 100 cubic yards of soils excavated from the former tank excavation and with 228 cubic yards of soils excavated from the new tank excavation. Before placement of the backfill, the tank excavation was lined with gravel in order to delineate the placed . backfill from the natural soils. Soils remaining in the excavation and in the adjacent areas containing petroleum hydrocarbons will be remediated by soil venting. r . 4 Product Line andP'u 1 Bls n r am lio Three product lines supplied the northwest fuel island,and the two fuel islands located southeast of ' the new tank excavation. On January 7, 1989, the three sets of product lines were excavated. Approximately 60 cubic yards of soil and backfill were excavated and stockpiled with the 100 cubic i 1 j yards of soil excavated from the former tank location. Soil samples were taken from 2 feet below each fuel island,and were identified as T-4,T-2,and T-3,with sampling locations shown is Figure 2. Tho chemical analysis of the roil samples are presented in Table 3 with laboratory data sheets presented in _ -Appendix-B. _Chemical analysis of soil samples collected from beneath the dispenser - - t island (T-1, T-2, and T-3) indicated concentrations of TPH at 15.0, 24.0, and 1,510.0 ppm, t. } respectively.. 44 ` On January 15, 1989,six additional soil samples were taken at 20-foot intervals within the product k ,�. line trenche=s. The chemical analyses of the soil samples are presented in Table 3 with laboratory