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1 <br /> 16 Plastic, silty clay was encountered The product line buried at approximately 1 5 feet bgs, extending <br />' approximately 85 feet in the horizontal direction from the pump island towards the 10,000 gallon UST <br /> (Figure 4 5) On the June 19, 1991 the entire length was exposed and the overlying soil was placed <br /> adjacent to the trench Soil directly beneath the pump island was stained and contained a slight <br /> hydrocarbon odor <br /> 4 3 2 Soil Sampline <br /> Soil samples below the underground lines were collected every 20 linear feet of pipe as prescribed <br />' by PHS-EHD The results of the initial and subsequent soil samples are shown on Figure 4 5, and are <br /> attached in Appendix M Soil with TPH/D concentrations exceeding 10,000 mg/kg were encountered <br /> at a total depth of 3 to 4 feet bgs approximately where a 90 degree coupling connected the pump to the <br /> product line <br /> Soils were excavated to a total depth of 5 feet bgs from the length of the trench and pump island, <br /> and resampled as shown on Figure 4 5 All soil samples taken at 5 feet bgs from the excavation reported <br />' nondetectable TPH/D and BTXE <br /> 4 3 3 Soil Treatment <br /> Port Costa Materials Inc (PCM), a permitted soil treatment facility in Port Costa, California was <br />' contracted to treat the 160 cubic yards of excavated soils with their thermal oxidation treatment system <br /> which destroys the hydrocarbons rendering the soils useful for recycling as building material PCM has <br />' restrictions on accepting volatile hydrocarbons or treating soils with heavy metals so four soil samples <br /> were collected from the excavation and submitted for analysis of volatile, diesel and waste oil <br /> hydrocarbons Concentrations of diesel ranged from 2,000 to 3,400 mg/kg TPH, heavy oils were <br />' reported from 260 to 470 mg/kg TPH, and volatile hydrocarbons, benzene, toluene, xylenes and <br /> ethylbenzene were not detected Soil was accepted for treatment and was transported to PCM, with Bills <br />' of Lading (Appendix L) for transportation of non-hazardous soil on August 5 and 6, 1991 <br /> 4 3 4 Site Restoration <br /> 1 <br /> After the soil was excavated and the confirmatory soil analytical results indicated that the <br />' excavation was clean, the excavation was backfilled Approximately 150 cubic yards of pea gravel was <br /> backfilled into the excavated area, and eight inches of Class II AB aggregate was compacted to 95 percent <br /> of its maximum dry density, as specified by PHS-EHD After soil compaction was tested and <br /> documented by Applied Inspection Management, the backfill was paved with six inches of asphalt All <br /> ti barricades were removed and the site was broom-swept clean on August 9, 1991 <br /> SAC36 046 21 <br />