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

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Packrat Contingency Seal The mine and reclamation plan calls for plugging the flows from the 10-Straight Shaft (3 gpm when last measured in 1994) and any historic drill holes with measurable flows. The 60-inch vent shaft that previously produced 0.4 gpm was backfilled by Umetco at the time of closure. The only other known significant source of ground water inflow is the water flowing into the Whirlwind Decline, which will be sealed off from the mine workings as discussed above. Energy Fuels believes that the evidence shows that there will be no water discharge from the Packrat Mine after mine closure. There has not been a discharge for many years from the Packrat Mine and Energy Fuels will be plugging the pre-existing shaft and drill holes that likely contribute most of the water currently present within the mine. Furthermore, any new vent shafts and exploration holes will be sealed/plugged to prevent migration of ground water from the upper water-bearing zones. Energy Fuels has agreed, however, to bond for a contingency seal in the Packrat Mine in the event that an area of the mine is opened where ground water inflow from above cannot be controlled with packers, grouting, or other less-costly measures. This seal would be placed as close as possible to the source of ground water to reduce the head requirement for the seal and to minimize the volume of water sealed within the Salt Wash sandstone. According to the evaluation performed by the DRMS using the Einarson and Abel (1990) template for bulk seal design, a concrete bulkhead seal of 1.6 feet can withstand a minimum head of 147 feet. This seal would be placed using low-pressure grout within the sandstone of the Salt Wash Formation. The Salt Wash sandstone is a competent rock with low hydraulic conductivity and high compressive strength (see Attachment A). Since the seal will be placed close to the source, Energy Fuels believes that the maximum head on the seal would be no greater than 147 feet; therefore, the contingency seal cost estimate has been based on a seal thickness of 1.6 feet. Bulkhead Costs The cost estimates for constructing the Whirlwind seal and the Packrat contingency seal are presented in Attachments B and C, respectively. The costs are very similar, as both seals would be 1.6 feet thick and constructed in the same manner. An additional cost for a coffer dam and extra piping is included for the contingency seal since it will be assumed that water may be flowing toward the seal from the updip mine workings. Cost estimation for the Whirlwind seal and Packrat contingency seal are based on the As- built Report for the Terry Tunnel Bulkhead. The Terry Tunnel Bulkhead was installed at the Sunnyside Mine in Silverton, CO and the DRMS considers this design to be satisfactory. This seal cost estimates provided in both Attachments B and C take into account the following differences between the Terry Tunnel Bulkhead and the proposed bulkheads for the Whirlwind Mine. 3