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Ms. Carol Oz August 12, 1999 Project 791700 Page 3 Representatives of the Stockton Fire Department (SFD), SJCPHS, and Pinnacle observed UST removal on June 17, 1999. Henderson personnel inerted the USTs with approximately 30 pounds of dry ice per 1,000 gallons of capacity. The SFD inspector approved UST removal when oxygen and lower explosive limit readings met UST removal guidelines. A Pinnacle geologist and personnel from the SJCPHS and SFD visually inspected the USTs after removal. The fiberglass USTs were in moderate to poor condition. The USTs were fractured in numerous locations. These fractures appeared to be caused by the bucket of the excavator during the uncovering of the USTs. Numerous small pin-holes and areas of discoloration were observed along welded seams of USTs T-1 and T-3. Each UST was marked with an identification number and loaded onto a flatbed truck for transport and disposal by Erickson, Inc., of Richmond, California. There was no evidence of hydrocarbon staining along the walls and the floor of the tank complex excavation. In addition, fill material below the USTs did not show any signs of hydrocarbon staining, although hydrocarbon odors were present. Groundwater was not encountered in the tank excavation. Product delivery line piping and vapor recovery lines were dismantled and removed the trenches after the UST removal activities were completed. Hydrocarbon staining of soil was observed beneath the fiberglass piping in the vicinity of vapor well VW-2 and in the soil below the northwestern pair of dispensers on the northern dispenser island (D-7 and D-8). Upon exposure of the product lines, it was observed that the duct tape was previously placed around piping in the vicinity of vapor extraction well W-2. Piping, dispenser, and sample locations are presented in Figure 2. Photographs were taken during UST and associated piping excavation and replacement. Photographs are presented in Appendix A. SOIL SAMPLING On June 17, 21, and 24, 1999, Pinnaclecollected soil samples from the gasoline UST excavation and piping trenches, and from beneath the former dispensers in accordance with the "Tri-Regional Board Staff Recommendations for Preliminary Evaluation and Investigation of Underground Tank Sites" (August 1992) and under the direction of the SJCPHS representatives, Carol Oz and Letitia Briggs. Soil sample locations are presented in Figure 2. CP\E:\ARCO\2186\R"ORTS\2186P105.DOC-9.51sg:1 P«titRCQe