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1 29 March 2004 S AGE-NC Project No. 97-0327 1 Page 9 of 12 On 15 November 2000, a representative of AGE conducted a search at the California Department 1 of Water Resources(CDWR)of well drillers reports for water wells located in the surrounding area. Drillers' reports for 15 domestic drinking water wells and one irrigation water well were located ' within a 2,000-foot radius were found. On 26 December 2000, a representative of AGE performed a reconnaissance of visually observable ' potential receptors within a 2,000-foot radius of the site. During the reconnaissance, AGE located potential domestic drinking water wells at nine separate locations. In addition, a total of 17 ground water monitoring wells were observed at one location. No other visible potential receptors were ' noted during the reconnaissance. On 26 December 2000, a representative of AGE conducted a search at the San Joaquin County Environmental Health Department for septic systems and well permits located in the surrounding area. Permits for three industrial water wells and one irrigation water well were located within a 2,000-foot radius were found. A location map depicting the results and a table summarizing the results of the sensitive receptor survey are included in Appendix 7.0. SITE CONCEPTUAL MODEL Based on the data collected to date from soil borings and ground water monitoring wells, AGE has ' developed a site conceptual model for the release,migration and distribution of the contaminants in the subsurface as described below: ' Release/s of petroleum hydrocarbons occurred from the.former USTs at the south-ends of the tanks (T1-A, T2-A and T3-A). Once released to the subsurface, the contaminants generally migrated vertically through semi-permeable sandy silt media and through more permeable silty fine sand 1 media(Vadose zone). At depths between 40 and 45 feet bsg, the contaminants appeared to spread laterally towards the northeast and southwest. Laterally, hydrocarbon-impacted soil is generally defined to the northwest by soil borings P-4, P-6 and P-12, and to the southeast by P-9 and MW-1, ' to the southwest by boring MW-4, and the north by boring P-7. The estimated total volume of petroleum (gasoline and diesel)-impacted soil is approximately 2 cubic yards. Since initiation of ground water monitoring in February 2000,ground water elevations have ranged from approximately 19.31 to 34.74 feet below mean sea level. Ground water flow direction at the site had been dominantly southernly(i.e. south-southwest to south-southeast).Representative maps ' of ground water elevations from years 2000 through 2003 are presented in Appendix A. i 1