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ri PRrt.IMINARY RFPOf2T ANO TANK Cl-45URC REPORT Tracy Boulevard Shelf 3725 Tracy Boulevard,Tracy,California Delta Project No.40-89.012 Page 11 A on May 4, 1990, after the former undergroand storage tanks were drained of water and removed, approadmately 2,700 gallons of ground water were pumped from the old tank excavation. The water was pumped to on-site holding tanks for later treatment and disposal. After the excavation was allowed to recharge for I hour,a ground water sample was collected with a Teflon bailer. Prior to sample collection, no evidence of floating product or a product sheen was observed. "Cha water sample was transferred to a volatile organic analyses vial and sent to an analytical laboratory for chemical analyses of BTEX,EDB,TPH, and organic Iead. 4.2 Ground Witter Conditions la the Former Tank Excavation Chemical results of the water samples collected from the former tank excavation and the space between the inner and outer walls of tanks T-6 and T-7 are presented in Table 7. The laboratory data sheets are presented in Appendix G. The results indicate that concentrations of TPH in the water from T-6 and T-7 were 21,000 and 19,000 ppb, respectively. Concentrations of BTEX ranged from less than the analytical method detection limits to 420 ppb- Included in Table 7 are the results of the chemical analyses on the ground water sample collected from the f= t former tank excavation. The results indicate that the.ITH concentration was 500 ppb and the BTEX W concentrations ranged from 5.4 to 58 ppb. The EDB and organic lead concentrations were below the analytical method detection limits. 4.9 Soil Cand[tlons in the Former Tank Fxcuvation on May 4, 1990, following the removal of the underground gasoline storage tanks, a Delta geologist collected soil samples from the sidewalk of the excavation adjacent to both ends of each tank at the soil/ground water interface. sample locations are shown in Figure S. The soil samples were collected 2 feet into the finished excavated surfaces of the sidewalk and approximately 9 feet below the ground surface followin;the methods recommended on page 13 of the Regional Board Staff Recommendations for Initial Evaluation and Investigation of Underground Tanks. The samples were shipped to a state-certified analytical laboratory and analyzed for BTEX and TPH as gasoline. In addition, the samples from the ends of the ---- ------------------------"------------former.leaded-gasoline._tank were analyzed for organic lead and EDB. Table 8 presents the laboratory analyses results,and Appendix H presents the laboratory data sheets. The results indicate that BTEX and TPH concentrations were below analytical method detection limits in - the soil samples collected near tha east and west ends of the unleaded regular tank(5W and 5E),and the west end of the leaded regular tank(6W). BTEX concentrations were below detection limits in tha sample from the east end of the[ended regular tank(6E)and the TPH concentration was 0.09 ppm Benzene and -�`