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Used-Oil UST Sampling Two soil samples were collected from beneath each end of the used-oil tank, in native soil, at approximately 9 5 feet bgs and labeled T4-E-9 5 and T4-W-9 5 The used--oil tank excavation measured approximately 19 feet long by 8 feet wide and 9 feet deep The excavation and sample locations are shown on Figure 2 Soil sample analytical results and sample depths are presented in Table A 4 Product Piping-Sampling Soil samples P-1-6 0, P-2-6 0, P-3-6 0, P-4-6 0, and P-5-5 5 were collected in native soil from trenches beneath the former product lines at depths of approximately 5 112 to 6 feet bgs Soil sample locations are shown on Figure 2 and soil sample analytical results are summarized in Table A OVEREXCAVATION SAMPLING ACTIVITIES Used-oil UST Excavation Activities • On April 26, 1996, the used-oil UST area, encompassing soil samples T4-E-9 5 and T4-W-9 5, was overexcavated The dimensions of the overexcavation were approximately 25 feet long by 21 feet wide by 21 feet deep, bgs Confirmation soil samples, designated WOX-2-16 5, WOX-3-16 5, WOX-4-16 5, WOX-5-16 5, and WOX-13-210, were collected from the sidewalls and bottom of the overexcavated area An additional soil sample, WOX-1-18 0, was collected on April 16, 1996, to estimate the approximate depth of overexcavation needed Confirmation soil sample depths ranged between approximately 16 112 and 21 feet bgs Approximately 500 cubic yards (cy) of soil were removed during used- oil UST excavation activities and stockpiled onsite The overexcavated area was backfilled with drain rock to approximately 12 feet bgs and to ground surface using soil stockpiles SPA(A-D) through SP-4(A-D) Soil stockpiles SPA(A-D) through SP-4(A-D) were generated from the removal of gasoline USTs described above and were used as backfifl material with the approval of Harlin Knoll of the SJCPHS Material from soil stockpiles SP-2(A-J)) and SP-4(A-D) was used as backfill initially and was subsequently covered by soil from stockpiles SPA(A-D) and SP-3(A-D) This ordering of stockpile backfilling was requested by Harlin Knoll and is based on chemical analytical results of these stockpiles presented below The used-oil UST overexcavation extent and soil sample locations are shown on Figure 3 and soil sample analytical data are presented in Table B 9983 Page 2