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Highway 93. This is equivalent to about nine truckloads of mine waste per day transported over a <br />one -year period. Each load of material would involve two trips through Bear Tooth Ranch, totaling 18 <br />large haul trucks per day traveling through this residential community. Local residents may oppose such <br />disruption, particularly for such an extended duration, as it would introduce local traffic safety hazards, <br />potential for spillage of mine waste, and would increase local carbon emissions and noise pollution. <br />Conclusions <br />Field investigation and characterization methods employed under TR -14 produced reasonable estimates <br />of the levels and spatial distribution of potential source term materials residing within the alluvial fill at <br />the Schwartzwalder Mine site. Terrestrial gamma radiation at the ground surface is not a reliable <br />indicator of subsurface source term material, partly because a layer of clean fill from the adjacent Black <br />Forest Mine was once placed across the surface of the alluvial fill. Direct sampling of subsurface <br />materials from test pits and open trenches yielded direct information with respect to areas requiring <br />remediation. In general, there are two basic areas at the site with radiologically elevated materials <br />residing in the alluvial fill at depths that are continually, seasonally or episodically exposed to alluvial <br />groundwater, and thus have the potential to impact water quality in Ralston Creek. <br />Uranium is the only water quality parameter demonstrated to be significantly impacted by alluvial fill <br />source term materials under actual hydrological and geochemical conditions that exist within the alluvial <br />fill. The SPLP testing (EPA method 1312) produced highly variable results that in general, appear to <br />underestimate the leaching potential of source term materials with respect to uranium, and overestimate <br />the leaching potential with respect to molybdenum. This conclusion is based on comparisons with actual <br />in -situ field measurements of alluvial source term materials and associated impacts to alluvial <br />groundwater in an area of the site that is scientifically suitable for such assessments. These results <br />indicate that SPLP laboratory testing is unsuitable for remedial assessments at the Schwartzwalder Mine <br />site. <br />A site - specific assessment of uranium leaching behavior based on actual in -situ field measurements was <br />used to develop a conservative cleanup criterion for removal of source term material within the alluvial <br />fill. Because uranium concentrations at the site are well correlated with Ra -226, and because approximate <br />Ra -226 concentrations can be readily assessed in the field with gamma survey instruments during <br />excavations, a Ra -226 concentration of 7 pCi /g will be used as the cleanup criterion for source term <br />removal. Based on this criterion, along with subsurface depth profile sampling data, the volume of <br />alluvial fill expected to require removal is in the range of 33,000 to 54,000 cubic yards. <br />Disposal options include placement of excavated source term materials within the underground mine <br />workings (in the CV Glory Hole), placement in an engineered above ground repository (a capped waste <br />rock pile), and offsite disposal at an appropriate facility in Colorado (at the Canon City Milling Facility or <br />at the Foothills Landfill). A summary of advantages and disadvantages for each disposal option is as <br />follows: <br />23 <br />