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PROBLEM ASSESSMENT F15KW <br /> 14800 West Frontage Road Manteca California <br /> 5.1.1 No Acton <br /> This alternative to sod cleanup involves one of the following 1) the completion of a health <br /> risk assessment indicating hydrocarbons in soil do not pose a threat to public health <br /> and/or groundwater A formal "Health Risk Assessment," prepared by a team of certified <br /> industrial hygienists, hydrogeologists, and engineers, discusses site-specific <br /> hydrogeologic, contaminant, and site features relating to existing and future biological <br /> receptors and groundwater, 2) a negotiated plan to monitor soil and/or groundwater <br /> quality without an active remediation system, 3) completion of a subsurface investigation <br /> that indicates hydrocarbons in soil are below required action levels <br /> All no-action options require horizontal and vertical definition of hydrocarbons in soil and <br /> I groundwater When the parameters have been defined, and no significant threat to the <br /> public health has been demonstrated, no action at a site may be considered a viable <br /> alternative <br /> 5.1.2 Soil Excavation <br /> Excavation of sod involves not only the physical removal, but physical and chemical <br /> characterization, disposal, and/or treatment either on or off site In general, excavation <br /> is performed to accomplish at least one of two objectives The first objective is to remove <br /> hydrocarbons from the subsurface This is feasible when hydrocarbon-bearing soil has <br /> been determined to be shallow enough for conventional excavation, site restrictions allow <br /> for the excavation, and the vertical and horizontal extent of hydrocarbons has been <br /> defined The second objective for soil excavation is to remove the source of potential <br /> impact to groundwater thereby either reducing or eliminating future monitoring and/or <br /> remediation requirements Before excavation is selected as an alternative, the site should <br /> be completely characterized and in-situ alternatives of soil remediation explored <br /> As mentioned above, once excavated, the soil must be treated and/or reclaimed or <br /> disposed of at an appropriate facility Restrictions on disposal of certain types of <br /> contaminants may increase the desirability of both on-site and off-site treatment options <br /> I5.1.3 In-Situ Bioremediation <br /> In-situ bioremediation consists of creating an environment in the subsurface to allow for <br /> organic compounds to be degraded by indigenous bacteria Creation of the environment <br /> is achieved by maintaining and monitoring adequate oxygen, pH, moisture, and nutrient <br /> levels in the soil Nutrient and hydrocarbon levels in groundwater should also be <br /> monitored Oxygen levels in the soil can be maintained with the use of air spargers, <br /> oxygen spargers, air infiltration (vapor extraction or injection systems), or hydrogen <br /> I peroxide infiltration To implement a bioremediation technology, the site must have soils <br /> with high intrinsic hydraulic conductivity to compensate for the decrease in hydraulic <br /> conductivity due to the increase in the bacteria population Typically, the hydraulic <br /> conductivity becomes a concern at a value less than 2 8 feet per day <br /> I90-097A PAR 9 <br />