2008-07-11_PERMIT FILE - M2007044 (7)

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SEAL DESIGN AND COST ESTIMATE 0 Whirlwind Hydrogeologic Setting Based on exploration drilling completed in 2007 and inspection of the Whirlwind decline, two schematic cross sections of the local lithology were developed. Figure Ll shows the location of the two cross sections. Figure L2 presents a northwest to southeast cross section (A-A') from four exploration drill holes to the lower level of the Whirlwind decline while Figure L3 shows a northeast to southwest cross section through the center of the decline. Known contacts are shown with a solid line while inferred contacts are shown with a dashed line. As shown on Figure L3, the decline for the Whirlwind Mine descends for 3,200 feet at a 6 percent grade through the Brushy Basin formation to the Salt Wash formation. The Brushy Basin formation consists of about 400 feet of low-permeable mudstones containing only a few sandstone lenses that are from 10 to 40 feet in thickness (see Figure L2). Limited volumes of unconfined, perched water are found in the lower portions of some of these sandstone lenses. The sandstone lenses were formed by fluvial processes, are lenticular in shape, and may not be continuous across the mesa. The recharge areas for these sandstone lenses are limited to short, steep outcrops on the southwest (i.e., updip) side of the mesa. The thick mudstone sequences prevent recharge from entering the sandstone lenses from above. Near the bottom of the Whirlwind decline, a sand lens within the Lower Brushy Basin is weeping ground water, which then flows down the decline into the mine workings. This lens historically made about 5 gpm, according to the records kept by the former operator. It currently makes about 1.5 gpm. As shown on the lower right-hand side of Figure L2, the lower sandstone lens of the Brushy Basin is very thin with numerous shale/mudstone partings where it intersects the Whirlwind decline. It does not appear that this lens, which is making water, continues much further to the southeast. Whirlwind Bulkhead At the time of closure, a bulkhead will be installed below the seepage in the decline to prevent this water from entering the mine. The water seeping into the decline is from an unconfined perched aquifer and will backup behind the bulkhead only to the point where the water is entering the decline. Water quality within this pool is expected to remain relatively stable because it will not be in contact with the mineralized zone of the Salt Wash. Although it is probably impossible to completely eliminate ground water inflow into the mine, it does appear that the inflows can be reduced to levels more consistent with what may have existed prior to historic mining operations in the area. The Whirlwind Decline was carefully evaluated to find a competent sandstone that is located below the entrance point of the water in the decline but before the start of the mineralized zone of the Salt Wash Formation, where the uranium ore is found. This evaluation was performed by Dick White, certified geologist for Energy Fuels. A