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Nftpor Appendix A AGE-NC No. 04-1168 Page 2 of 5 SITE STRATIGRAPHY Based on previous investigations, the soil profile from 15 to 30 feet below surface grade (bsg)is characterized by an orange brown silt with little or no plasticity and low consistency. The soil profile from 35 to 40 feet bsg is characterized by an orange brown clayey silt and an olive brown silt is present at 45 feet bsg. Olive brown and blue grey silty clays were encountered from 50 to 70 feet bsg in boring MW1 and 63 to 70 feet bsg in boring MW3, whereas a silty sand was encountered at approximately 70 feet bsg in boring MW2. UNDERGROUND STORAGE TANK REMOVAL According to records on file with the San Joaquin County Environmental Health Department(SJCEHD),four underground storage tanks (USTs)were formerly located on the property. Three of the USTs were located in a common excavation,west of the on-site building; a fourth UST, presumably used for waste oil, was located south (behind) the on-site building. In 1998, the four USTs were removed by Paydirt Excavation. The USTs had been out of commission and empty at the time of removal. Soil samples were collected from the UST excavation,former piping areas and dispenser island area. Petroleum hydrocarbons were not detected in soil samples collected at the time of removal. SITE ASSESSMENT ACTIVITIES On 02 July 2004, AGE published Limited Subsurface Investigation Work Plan which reported all purposed investigative activities,installations,and findings for three preliminary soil borings. On 19 July 2004, three soil probe borings (B1 though 133) were advanced at the site utilizing a van-mounted Geoprobe 5400. Boring B1 was advanced in the former tank pit to a depth of approximately 30 feet bsg at which point probe advancement ceased due to subsurface refusal as the result of pea gravel falling into the boring from the overlying tank pit. Boring B2 was advanced as a continuation of B1, located 10 feet north of B1 just outside the tank pit. Samples were collected in boring B2 starting at 35 feet bsg to a total depth of 45 feet bsg. Boring B3 was advanced in the former dispenser location to a total depth of 20 feet bsg. Soil boring locations are depicted on Figure 2. Samples were collected from the borings at discrete five-foot intervals. A total of five soil Advanced GeoEnvironmental