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UPS July 15, 1992 Job No. 074-013 Page 3 gasoline, slight levels of all the BTEX substances, no EDB, no organic lead and 16 ppm total lead. The two samples obtained from soil removed during overexcavation of the gasoline tank excavation were analyzed for gasoline and BTEX only; none was detected in either sample. The stockpiled soil excavated during removal of the waste- oil tank does not appear to have been sampled. Based on excavation and overexcavation dimensions reported by Groundwater Technology, it appeared that stockpiled soil included about 240 cubic yards from the gasoline tank excavation and about 20 cubic yards from the waste-oil tank excavation. CURRENT WORK FIELD WORK ' Our field work has included the overexcavation, sampling and backfill of the waste oil tank excavation, as well as sampling of soil stockpiles. Mike lnfurna of the SJCEHD was on-site during field activities and directed sampling operations. Ramos Environmental provided subcontract excavation and backfill services. Because the excavation work was performed near existing building foundations, the work was directed by an engineer from our staff experienced in both geotechnical and ' environmental engineering. Following the earlier removal of the tank by others, the excavation measured about 5.5 by 11 by 10 feet deep. During our excavation work, competent sidewall soils were encountered (stiff clays underlain by variable cemented silts) and allowed for ' overexcavation to final dimensions of nine by 15 by 14 feet deep. At these limits, soil was obtained with the backhoe from the center of the excavation bottom and at the midpoint of each sidewali's intersection with the bottom. Samples were collected from the backhoe bucket by quickly hand driving precleaned brass tubes into the freshly excavated soil. The ends of the sample tubes were covered with foil and plastic endcaps. The samples then were labeled, logged onto a chain-of-custody form and placed on ice. Following the sampling work, the excavation was backfilled with aggregate base material. The material was placed and compacted in approximate ten-inch lifts. Compaction was performed with a hydraulically-driven vibratory plate attached to the end of the backhoe arm, Both prior to the excavation work and following backfill, elevations of targets chiseled . into the adjacent building panels were measured. The approximate plan locations of the settlement monitoring targets are shown together with the drain grate used as ■ Geotechnical cc ' c l6