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i SWOO Mr. Kenneth Earnest July 30, 1993 Page 3 samples will be submitted to the analytical laboratory for analysis of BTEX, TPHg, total lead concentrations, and EDB. If the total lead analysis for any one soil sample (from beneath the tanks or product lines) indicates a lead concentration greater than 13 mg/kg, that sample will also be analyzed for soluble lead. Previous soil sample analytical results indicate that overexcavation may not be necessary. However, upon receipt of results of the soil samples collected from beneath the product lines and the tank basin, soil at the limit of the excavation containing BTEX, TPHg, lead, or EDB above limits specified in the Tri-Regional Guidelines and Title 22 will be overexcavated and stockpiled on site until analytical results are obtained and transportation can be arranged for removal of the soil to the Ultramar refinery facility or to an appropriate landfill. The extent of soil overexcavation may be limited by the depth of the reach of the excavator (approximately 20 feet below grade), by property boundaries, or by the presence of existing structures. The maximum amount of soil to be overexcavated, if necessary, is approximately 1,500 cubic yards (Figure 3). If the volume of soil to be removed is economically unfeasible, other remedial alternatives will be explored. � Subject to the limitations discussed above, all areas of overexcavation will be sampled to confirm that only soil containing levels of petroleum hydrocarbon constituents below state action levels will be allowed to remain in place. Confirmation soil samples will be collected from the middle of each side wall (north, south, east, and west) at the intersection of the side wall and floor and at the center of the floor of the excavation (Figure 3). If the excavation is extensive, additional soil samples may be necessary to confirm that the removal of petroleum hydrocarbon constituents is complete. The locations of these confirmation samples, if necessary, will be determined by Ultramar's representative and confirmed with San Joaquin County's representative. San Joaquin County will be properly notified prior to commencement of work and kept informed as new information (i.e., soil sample results) is obtained. It is recommended that three copies of this letter report be forwarded to: Ms. Mary Maze Environmental Health Department County of San Joaquin 445 North San Joaquin Stockton, CA 95201 lrptoos.mj ACTON•NUCKEL,SON• van DAM,INC. Consulting Scientists,Engineers,and Geologists