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Dustin Czapla <br />Loesch Pit, M-1981-068, Garfield County, CO. <br />Technical Revision - Pit wall liner <br />Page 5 of 7 <br />Oct. 4, 2010 <br />In addition to controlling seepage during operations an added benefit of lining the pit is to <br />minimize the potential for augmentation water post-operations. If the pit were to remain <br />completely dry, no groundwater would be intercepted, and no augmentation water would be <br />required, as there would be no evaporative loss of groundwater. Conversely, such a water <br />tight liner would be useful for the storage of water. <br />It is currently the Operator's plans to finish excavating Phase 11 as shown of Figure 1, and the <br />portion of Phase III that is on the east side of the access road. Upon completion, the <br />remainder of the exposed pit walls may be lined. It should be noted that the liner is not <br />needed around the entirety of the pit to control an inflow of groundwater. In areas that are <br />relatively dry, the benefit of the liner will be the possibility of better retention of water within the <br />completed pit. The Operator wishes to reserve the option of not placing liner in the existing pit, <br />or other pits, if it is deemed it is not necessary. <br />POST RECLAMATION CONDITIONS <br />There are two key questions regarding the liner as to its impact on the final reclamation plan. <br />First, does it affect the hydrology of the Colorado River, and secondly, does it have any impact <br />on slope stability? <br />Hydrology The presence of the liner has no material effect on groundwater. Groundwater <br />historically flowed through the site and directly into the Colorado River. With the pit in place, <br />groundwater either flows around the pit, or seepage into the pit is collected and returned to the <br />river via pumping. The liner is not installed as a completely impermeable barrier. During <br />mining operations the groundwater level in the pit is kept artificially low by pumping. Once <br />pumping ceases, the pit may slowly fill until the water level matches the groundwater level <br />outside of the pit. <br />As discussed previously, the controlling factors for the water level in the post-reclamation pit <br />will likely be boundary conditions, e.g., the drain ditch on the north and east side of the pit, or a <br />WATZR FUWURce coNSULLwrs, u.c <br />....i