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Sacramento Insulation Contractors Project No. EOC-96-028 LEOC personnel and Mr. Knoll also discussed the need to collect surficial soil samples from the area to the south of the warehouse where the soil removed during the tank removal was spread F on the ground surface. Since tank removal and spreading of the soil had occurred 8 years earlier and it was impossible to accurately locate the area where the soil had been spread, it was agreed by EOC and Mr. Knoll that sampling of the soil to the south of the warehouse was not f beneficial and would be considered unnecessary. �-- Following the excavation of Borings B1 and B2, West Hazmat filled each boring with bentonite pellets and grout and sealed the boreholes at the ground surface with concrete. At Mr. Knoll's direction, soil excavated from the boreholes was spread on the ground surface to the south of t.. the warehouse. { GEOLOGY ENCOUNTERED IN THE BORINGS Soils encountered during the performance of the boring activities included yellowish to olive to t dark brown silty clays to clayey silt, with a trace of fine sands. A silty fine sand layer was observed from approximately 32 feet to 35 feet bgs and below 50 feet bgs in Boring B1. Groundwater was measured in Boring B1 at an approximate depth of 56 feet bgs. Clayey fine sand fill soil was apparent from ground surface to approximately 10 feet bgs in Boring B2, indicating the probable former location of the UST. Discoloration of soils and petroleum hydrocarbon odors were not observed during the performance of the soil boring activities. A description of the soils encountered are presented on the boring logs in Appendix B. SUMMARY AND CONCLUSIONS r A review of the results of soil boring activity including the collection and analysis of soil and groundwater samples indicates the following: r Summary 1. Two borings were advanced at the site. Boring B1 was terminated at an approximate depth of 60 feet bgs and Boring B2 was terminated at approximately 36.5 feet bgs. r 2. Concentrations of TPH and BTEX were not measured above the detection limit in the 9 soil samples analyzed from Borings 81 and B2. 3. Groundwater was measured at approximately 56 feet bgs in Boring B1. A borehole groundwater sample collected from Boring B1 did not contain detectable concentrations of TPH and BTEX. 1 �- Conclusions Detectable concentrations of petroleum hydrocarbons were not measured in soil and groundwater samples collected from the site, indicating that continued petroleum hydrocarbon impact from the former operation of a UST on the site appears unlikely. Mitigation efforts performed during the removal of the tank appear to have addressed the release of petroleum L hydrocarbons from the UST. f L r L EnvirOmega Consultants 4 December 11,1996 t