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-8- <br />• <br />of numerous spoil piles at the existing Energy Fuels Mine. <br />When compacted to high density, fills constructed from the spoil <br />will be relatively impervious. Rock used to construct the fill will be <br />a combination of claystone, sandstones and occasionally some layers of <br />siltstone. All these materials tend to degrade with time and based on <br />performance of existing haul roads become quite slick during periods <br />of precipitation. We believe surfacing of the haul roads with gravel <br />should improve the performance of the subgrade and decrease operational <br />problems. Design of gravel surfacing was beyond the scope of this in- <br />vestigation. <br />CUT SLOPE STABILITY <br />• The upper stiff clay soils which are the result of weathering of <br />the underlying sedimentary bedrocks are capable of standing on a vertical <br />slope for a short duration. We also have experience with cutting these <br />slopes at 1:1 slopes for short-term construction periods. For a long- <br />term period we believe a 1.5:1 (horizontal to vertical) slope should be <br />used in the upper residual clays and softer phases of the sedimentary rock. <br />We estimate the factor of safety for these cut slopes will be on the <br />order of 3. No seepage or wet areas were evident in the high ridge areas <br />where the haul roads are planned. If ground water is encountered during <br />the construction of cuts for these roads, it may be necessary to locally <br />flatten some cut slopes to achieve the desired stability. Where cuts <br />extend into the underlying formation materials, the cut slopes can be <br />• made as steep as 60 degrees with a factor of safety on the order of 2. 3. <br />