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GEOSYNTEC CONSULTANTS <br /> Ms. Amy Terrell <br /> 25 August 2003 <br /> Page 5 <br /> Tarp,et Application Areas <br /> In the 150 ft by 50 ft former tank farm area at the site, HRC Primer would be <br /> injected vertically or horizontally in the unpaved areas (i.e. not where the new overhead <br /> bins are located). If vertical injection via GeoProbe were used, then the injections <br /> would be spaced on approximately 10 ft centers. If induced horizontal fractures are <br /> used, the spacing will be based on the radial distance of fracture, as estimated in the <br /> field. In either case, the injection grid would be identified in the field, and would be <br /> adjusted depending on the locations of the concrete pads and fertilizer bins. <br /> The injections would be targeted into two vertical intervals: an upper zone at about <br /> 2 ft bgs and a deeper zone at about 17 feet bgs. All injections would be at least 5 ft <br /> above the highest encountered groundwater. <br /> As a follow-up to the HRC Primer injections, soil samples would be collected from <br /> three locations at one-year intervals after the injections. Depth-discrete samples will be <br /> analyzed for nitrate as nitrogen by EPA Method 300.0 and ammonia as nitrogen by <br /> EPA Method 350.3. <br /> Implementation Sequence <br /> As mentioned previously, bioremediation is known to be effective for enhancing <br /> denitrification of nitrate-nitrogen. Denitrification occurs under reduced oxygen <br /> (anaerobic) conditions. The effect of this treatment on ammonium-nitrogen is less well <br /> understood. <br /> There is extensive literature indicating that nitrification (the two-step process in <br /> which ammonium is oxidized to nitrite, then to nitrate) plays a significant role in <br /> attenuating ammonium both in unsaturated soil and in groundwater (e.g. Buss, et al, <br /> 2003; Duthy, 1993). However, anaerobic ammonium oxidation to nitrate and <br /> subsequent denitrification has not been well studied or documented. Consequently, <br /> WFS proposes to complete a laboratory microcosm evaluation of the effects of carbon <br /> source addition to site soil before moving to a field application. <br /> PAPRJ2003REM\WFS\VER\Soi1 Plan 2003\RAP-Soil 8-25.doc <br /> RECYCLED AND RECYCLABLE <br />