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RECEIVED <br />d. Whirlwind Bulkhead <br />JAN 16 2008 <br />vivia~~~~ ~~ rteaamation, <br />Mining and Safety <br />The Whirlwind Decline was carefully evaluated to find a competent sandstone that is <br />located below the entrance point of the water in the decline but before the start of the <br />mineralized zone of the Salt Wash Formation, where the uranium ore is found. This <br />evaluation was performed by Dick White, certified geologist for Energy Fuels. A <br />competent sandstone zone was found in anon-mineralized area at the very top of the <br />Salt Wash Formation. This proposed seal location is shown on Figure F1 and Map C2 <br />included in Attachments E and C, respectively. As is seen in Figure F1, the estimated <br />vertical distance from the seal location to the water entrance point is 23 feet. Figure 2 <br />of Attachment E shows a conceptual layout of the 1.6-foot thick bulkhead, including <br />forms, timber, piping, and the surrounding rock. <br />The sandstone was sampled and laboratory tests were conducted for compressive <br />strength and hydraulic conductivity. These test results are presented in Attachment B. <br />The compressive strength was found to be 8,490 pounds per square inch (psi). This is <br />about twice the compressive strength of cured, high-quality concrete and more than <br />adequate for the seal installation. The hydraulic conductivity was found to be 2.5 x <br />10"2 m/d (equivalent to 2.9 x 10"5 cm/s). Although not completely impermeable, it is <br />within the range of an aquiclude. The plan for the seal is to employ low pressure <br />grouting of the surrounding sandstone to ensure that water does not bypass the seal. <br />Mr. White also prepared an analysis of the sandstone beds of the Brushy Basin zone <br />based on his experience with drilling on Beaver Mesa and other similar areas within <br />the Colorado Plateau. His analysis, cross-sections and conclusions are presented in <br />Attachment A. He concludes that the expected water level above the seal would be no <br />more than 15 vertical feet above the water entrance point. Because the seal will be <br />located about 23 vertical feet below the entrance point, the total estimated head on the <br />seal will be no more than 38 feet. Using the Einarson and Abel (1990) template, this <br />would result in a theoretical seal concrete thickness of 0.40 feet Because a seal of this <br />thickness would be difficult to adequately anchor in the surrounding sandstone, <br />Energy Fuels commits to using a seal thickness of 1.6 feet. This seal would be <br />capable of handling 147 feet of head, which is very conservative for this site-specific <br />application. <br />Cost estimation for this seal as well as the Packrat contingency seal (see Attachment <br />H) are based on the As-built Report for the Terry Tunnel Bulkhead. The Terry Tunnel <br />Bulkhead was installed at the Sunnyside Mine in Silverton, CO and the DRMS <br />considers this design to be satisfactory. A revised bond estimate for the Whirlwind <br />seal in included as Attachment I. The seal estimates provided in both Attachments H <br />and I take into account the following differences between the Terry Tunnel Bulkhead <br />and the proposed bulkheads for the Whirlwind Mine. <br />• Labor costs have increased over time. A list of the current labor costs for Energy <br />Fuels is presented in Attachment I. <br />La1er~~ duels Resc~arces C~;c~rlac~ratitm 44 I.Tnic~~~ t3ctule~artl, Suite fi0{) 19 <br />1.,aketi~-c>t~~ci. C~`(:} 80123 ('ho~~~: 3(l3-t)7~k-214 <br />