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When the contaminated soil has been removed, a second on-site excavation <br /> will be used to generate fill for the first excavation to allow immediate <br /> closure and paving of the maintenance shop area. This on-site fill and the <br /> clean overburden soil will then be returned to the first excavation, graded, <br /> and packed. The excavated area will then be repaved with asphalt. <br /> Landfarming includes treating soils with nutrients and water in order to <br /> promote the natural aerobic bacterial degradation of hydrocarbon contaminants <br />' in the soil. Landfarming at the site will be carried out on approximately one <br /> acre of available space where the total amount of contaminated soil can be <br /> laid out in an even 1-foot thick layer. <br /> To prepare the site for the Landfarming operation, Dames b Moore <br /> recommends using the existing on-site clayey top soil to create a compacted 1 <br /> foot thick liner over the entire landfarming surface. Physical testing of the <br />' proposed soils will be conducted to determine suitability of on-site soils for <br /> use as a compacted liner. The compacted clay liner will be designed to have a <br /> permeability of no less than 10-6 cm/sec. The contaminated soils will be <br /> placed on the clay liner and disked bi-weekly, watered to maintain optimum <br /> 1 soil moisture and prevent excessive particulate emissions, and allowed to <br /> aerate for several months. An earthen berm will be constructed around the <br /> landfarm to control potential surface water runoff and erosion. <br /> Soil samples from the landfarmed soil will be collected and analyzed on a <br />' monthly basis for total petroleum hydrocarbons (EPA Method 8015, Modified). <br /> When soil concentrations decrease to below 100 ppm, the landfarm soil will be <br />' used to backfill the on-site excavation. After remediation is complete, the <br /> underlying clay liner will be tested. <br /> 8-3 <br /> GGA/0209b/276a <br />