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1 <br /> with clean fill dirt and compacted using construction equipment The <br /> backfill area was subsequently paved with asphalt cover <br /> ' 34.1 Soil Aeration <br /> Excavated soil was stockpiled on site with the Site #1 soil for aeration <br /> The aeration pile was covered with 6 mil polyethylene sheeting at all <br /> times, except when adding or removing soil The aeration pile was <br /> secured inside a padlocked fence A conventional tractor with disc-tilling <br /> attachment was used to aerate the Site #2 soil for a total of 16 days at a <br /> rate of 600 cubic yards per day The aerated soil was sampled for post <br /> treatment confirmation on 13 December 1993 by ERM personnel under <br /> San Joaquin County supervision Twelve confirmation samples were <br /> analyzed to confirm that the cleanup goals (100 ppm for TPH-g and 1 ppm <br /> for total BTEX) was attained and no further aeration was needed A letter <br /> describing the soil aeration process and the post treatment confirmation <br /> data was prepared by ERM and sent to the Unified Air Pollution Control <br /> ' District on 29 December 1993 <br /> After laboratory analyses confirmed that all chemical concentrations were <br />' below applicable detection limits, the treated soil was spread along the <br /> northeast corner of the property as proposed in the Final Remediation <br /> Plan (ERM, September 1993) <br />' 35 ADDITIONAL CHARACTERIZATION <br /> As discussed in Section 2, in September 1994 Catellus conducted <br />' additional soil sampling within the former excavation footprint and <br /> underneath the existing building to verify that residual hydrocarbon <br />' concentrations, if present in site soils, would not pose a significant risk to <br /> human health and the environment The results of the additional <br /> characterization activities were presented in the Environmental <br /> Conditions Report (ERM,July 3995) Four borings (S2-B1 through S2-B4) <br /> were completed to a maximum depth of 18 feet bgs Samples were <br /> analyzed from two depth intervals from S2-B1, three depth intervals from <br />' S2-B2 and S2-B4, and four depth intervals from S2-B3 The data collected <br /> during this investigation verified the accuracy of the 1993 excavation <br /> confirmation sampling and supported the 1993 confirmation sampling <br />' results that indicated that soils exceeding the TPH cleanup goal had been <br /> excavated A figure summarizing the TPH concentrations detected in <br /> soils in the former Tank Site #2 area is included in Appendix B <br /> The data indicated that a limited volume of soils containing TPH at levels <br /> higher than the 100 mg/kg cleanup goal were present beneath the <br />' ERM 16 CATELE US/2996 IU-1 U/13/99 <br />