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1 <br /> SITE CLOS M EVALUATION REPORT <br /> Ultramar Station No. 696 <br /> 2448 West Kettleman Lane <br /> Lodi, California <br /> ` Delta project No. D093-916 <br /> Page 2 <br /> ' 2.2 Site H'istor <br /> Prior to acquisition of the site by Ultramar in July 1990, the site was owned and operated by Conoco, <br /> ' Inc. The presence of petroleum hydrocarbons in soil and ground water beneath the site was detected in <br /> early 1985. Since that time numerous investigations have been conducted at the site. There have been <br /> 1 37 ground water monitoring or soil vapor extraction (SVE) wells installed at the site and on adjacent <br /> properties. A total of 21 of these wells, and an on-site domestic water supply, have been destroyed. <br /> Three single-walled underground fuel storage tanks were removed from the site in March 1989 and were <br /> replaced by the three existing double-walled tanks. Remedial activities have included installation of a <br /> ' ground water pump and treat system which was in operation from January 1986 until approximately Iate <br /> 1988, installation of a SVE treatment system which was in operation from December 1989 through <br /> April 1994, and excavation of soil from the tank pit and product line locations. <br /> 2.3 Site Vicinity Well Inventory <br /> ' An inventory of domestic and agricultural supply wells in the vicinity of the site was conducted by IT <br /> Corporation in May 1985. A total of 22 wells were located within an approximate one-half mile radius <br /> of the site at that time. Copies of the well inventory and well location map are presented in Appendix A. <br /> r3.0 SUMMARY OF INVESTIGATION RESULTS <br /> 3.1 Site Geology <br /> ' Soils beneath the site are predominantly sand and silty sand with relatively thin and discontinuous layers <br /> of silt and clay. Geologic cross-sections have been prepared to illustrate the inferred subsurface <br /> ' conditions at the site. A geologic cross-section location map is presented as Figure 4, and geologic cross- <br /> sections A-A' and B-B' are presented in Figures 5 and 6, respectively. <br /> 1 <br /> 3.2 Site Hydrogeology <br /> ' When the first monitoring wells were installed at the site in March 1985 ground water was reportedly = <br /> present at a depth of approximately 39 feet below surface grade (bsg). The depth to ground water has <br /> increased over the years and is now approximately 55 feet bsg. A summary of available ground water <br /> RPT134.ST5 <br />