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Mr Michael Walton 0 Walton Engineering ' August 4, 1998 • storage tanks were unearthed and then removed by Walton Engineering, Inc , on June 30, 1998 Prior to removing the storage tanks from the ground,the tanks were rinsed and evacuated by Norcal I Oil of Modesto, California, and then approximately 300 pounds of dry ice was placed in each tank The dry ice displaced oxygen(O2) to less than 4% in each of the tanks and lowered the LEL (lower ' explosive limit) to less than 8% in each of the tanks After removing the storage tanks from the ground, the tanks were inspected and found to be in good condition The three tanks were hauled from the site and disposed of by West Coast Equipment of Turlock,California A representative from ' San Joaquin County Environmental Health Division (SJCEHD) was present to supervise the tank removal and soil sampling operation ' SOIL SAMPLE COLLECTION Native soil strata encountered in the tank excavation at the site consisted of light brown silty sand and isand Field evidence for subsurface soil contamination was observed only beneath the eastern end of the former fuel dispenser island Minor soil contamination observed beneath the former fuel dispenser island was over excavated and removed from the subsurface prior to sample collection INative soil encountered in the tank excavation did not appear to have an odor of petroleum-based fuel hydrocarbons IAfter removing sandy tank backfill material from the open excavation, soil samples were collected from beneath each end of the three former underground fuel storage tanks (Figure 2) Native soil samples were collected from beneath each of the tanks (T1 through T3) at approximately 17 feet below ground surface by removing soil from the base of the excavation using an excavator and then immediately driving a clean sample sleeve into a relatively undisturbed part of the soil contained in ' the excavator bucket Each of these soil samples were collected by driving a stainless steel sample sleeve into the native soil using a hand-operated, AMS percussion core sampler Individual soil samples were collected in situ from beneath each end of the former fuel dispenser island (FD 1 and ' FD2 on Figure 2) Each individual sample sleeve containing a soil sample was sealed with plastic end caps,labeled with the project and sample identification numbers and date, and placed in iced storage immediately following sample collection The soil samples were delivered to the environmental laboratory, while adhering to the required chain of custody procedures (Appendix A) I STOCKPILE SOIL SAMPLE COLLECTION ' A total of four individual soil samples(representing one soil sample composite)were collected from every approximated 100 cubic yards of stockpiled soil material(Figure 2) Soil and backfill material removed from the open excavation during the tank removal operation was stockpiled on asphaltic- concrete adjacent to the open tank excavation Grayland collected a total of three soil sample composites from the soil stockpile (SP1) Each individual soil sample was collected using the percussion core sampler by first removing approximately 1 foot of soil/backfill material from the ' surface of the pile and then driving a clean stainless steel sleeve into the freshly exposed surface of . the pile Grayland collected two additional soil sample composites from the soil and backfill material I GRA YLAND ENVIRONMENTAL Grayland 022-140 trr 2