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/►�L'1��illNC <br /> pit should be refilled with noncontaminated soil from the excavation, as <br /> well as drain rock and imported fill material . <br /> To remove the contamination from the excavated soil , bioremediation, <br /> the use of naturally occurring bacteria to consume the hydrocarbon <br /> contamination 7s suggested as the method of choice. The process <br /> requires an on-site work area, preferably with controlled entry. The <br /> corner of the enclosed parking lot behind the Pacific Bell Stockton <br /> facility is ideal . Once the contaminated soil 7s moved to the parking <br /> area, the following steps would be involved in the bioremediation <br /> process. The contaminated soil would be inoculated with a <br /> nutrient/bacteria mixture, and evenly distributed throughout. The <br /> inoculated soil would then be heaped insitu, incorporating a PVC <br /> ventilation system powered by a electric blower to supply oxygen to the <br /> bacteria. The heap would be enclosed in plastic sheeting to protect it <br /> from the elements and maintained for approximately eight weeks. During <br /> this time period, the bacteria would be increasing in number and <br /> consuming the hydrocarbon contamination present. The soil would then be <br /> resampled for TPH If the resulting analyses are below 100 ppm TPH, the <br /> soil could then be disposed of at a sanitary landfill . If higher levels <br /> are still present, a reinoculation of bacteria and nutrients would take <br /> place and the soil resampled after four weeks. <br /> 5 3 Recommendations <br /> Based on the findings of the Stockton borehole samplings, the <br /> following recommendations are made: <br /> a 88-11-1 : The soil from the site of the UST should be excavated <br /> to remove all TPH contamination in concentrations of <br /> greater than 100 ppm. The excavation should be <br /> completed in a manner so as to ensure the structural <br /> integrity of the adjacent Pacific Bell facility and <br /> telephone transmission cables, while maintaining strict <br /> safety controls. The excavation would then be filled <br /> with noncontaminated soil from the excavation as well <br /> as drain rock and imported fill material . <br /> i 15 <br />