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!'RF1,IMINARY REPORT ANi3 TANK CLOSURE REPORT Tracy Boulevard Shell 3723 Trucy Boulevard,Tracy,California Delta Project No.40.89.012 Page 9 Three, soil borings were drilled at locations MW-lA, NfW-2A, and MW-3A and were converted to monitoring wells. Three soil samples,collected at depths of 5 feet below the ground surface,were sent to the laboratory for chemical analysis of BTEX and TPH. Concentrations of BTFX and TPH in samples collected from MW-lA and MW-3A were below the analytical method detection limits of 0.005 and 1.0 ppm,respectively. Concentrations of benzene and toluene in the sample collected from MW-2A were below 0.005 ppm;concentrations of ethylbenzene,xylenes,and TPH were 0.013,0.052,and 2 ppm,respectively. 3.7 Ground Water Chemist On September 26, 1989,monitoring wells MW-1,MW-2,and MW-3 were purged by removing seven well casing volumes of water from each well. Ground water samples were collected from each well and sent to a state-certified laboratory for analysis of BTFX and TPH. In addition,the ground water from monitoring well MW-1 was analyzed for oil and grease, metals,nitrogen as ammonia, cyanide,fluoride, total organic halogens, formaldehyde, fatty acids, semivolatile organic acids,pesticides, and polychlorinated biphenyls (PCBs). The additional analyses were performed in order to obtain a wastewater discharge permit from the City of Tracy. The results from the chemical analysis of petroleum constituents from the three monitoring wells are presented in Table 6. Copies of the certified laboratory reports are g;esented in Appendix F. On August 28,1990,monitoring wells MW-IA,MW-2A,and MW-3A were purged by removing three well casing volumes of water from each well. Ground water samples were collected from each well and se4nt to a state-certified laboratory for analysis of BTFX and TPH. The results from the chemical analysis of petroleum constituents are presented in Table 6. Copies of the certified laboratory reports are presented in Appendix F. Chemical analyses of the ground water samples for BTFX and TPH show that the concentrations were below the laboratory analytical method detection limits. 4.0 RESULTS OF TANK CLOSURE ACTMTTFS — Appro)dmately.1,700 cubic yards of soil were excavated during tank and product line removal, new tank excavation work,and the overexcavation of soil containing petroleum hydrocarbons. As excavation work proceeded, a Delta geologist was on site to segregate soils. Soils were segregated and stvckpi:ed on site based on subjective analyses and readings taken with a PID. If a PID reading was zero and there was no ~ staining of the soil,it was stockpiled in the'clean'pile;if a reading was below JOG ppm.or if the soil was stained,it was stockpiled in the"dirty'pile;if a reading was over 100 Qpm, the soil was stockpiled in the