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FARR ASSOCIATES 4.0 TANK AND SOIL REMOVAL ACTIONS ' 41 Tank Excavation In September 1989, the four tanks and associated piping at the site were removed from the site by SEMCO under permit and direction of PHS/EHD Soil sampling from the bottom of each tank excavation was performed to evaluate past potential leakage and/or over filling of the tanks The soil samples were analyzed for total petroleum hydrocarbons as gasoline (TPH-g), TPH as diesel (TPH-d), TPH as kerosene (TPH-k), and TPH as motor oil (TPH-o), BTEX, chlorinated hydrocarbons, organic lead, and ethylene dibromide A summary of the analytical results for these samples are included in Appendix A, Table A-1 Four soil samples were collected from beneath Tanks # 1 and 2 at an approximate depth of 12 feet bgs (WHF,November 1990) All four samples were non-detect for the constituents analyzed Three additional soil samples were collected adjacent to the product line at an approximate depth of 5 feet bgs (WHF November 1990) which was situated to the south of the two tanks Two of these samples were non-detect for the constituents analyzed The third sample contained 78 mg/kg TPH-d The soil sample collected from beneath Tank 43 detected 12,000 mg/kg TPH-o The soil samples collected from beneath Tank 44 was non-detect, although observations did note what appeared to be petroleum-affected soil within Tank #4 excavation 42 Soil Removals and Confirmation Sampling Results 4 2 1 Tank No 3 In January of 1990, petroleum-affected soil was excavated from the former Tank #3 area by WHF Environmental Consultants The excavation extended partially into Union Street encompassing a rectangular area of approximately 500 square feet to a depth of approximately 25 ft bgs (Figure 3) The excavation was terminated on the north to protect a utility pole and storm drain Approximately 550 cubic yards of soil were removed from the excavation and remediated off-site at another Union lee property located at 1320 West Wi,ber Street, Stockton Confirmation soil samples were collected from the north, east, south and west walls of the excavation at approximately 20 feet bgs, as well as on the northern and southern floor of the excavation at approximately 25 feet bgs (Figure A-1, Appendix. A) The samples were analyzed for oil and grease, TPH-o, TPH-g, TPH-d, TPH-k, lead, and BTEX The analytical results of the soil samples are presented on Table A-2, Appendix A Oil and grease (200 mg/kg) and ethylbenzene (57 ug/kg) were detected in the south floor sample,while 285 mg/kg oil and grease were detected in the northern wall sample Based on these soil concentrations and visual tobservations, WHF estimated the total volume of residual contamination to be 12 5 cubic yards of soil at 111 mg/kg oil/grease and 20 ug/kg ethylbenzene (WHI, February 1993) The excavation was backfilled with"clean" pea gravel • C\My�iles\AnnelwpwmlprojecislumonlClosureRpt wpd 5