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<br />• The confined overburden aquifer will be replaced as a result of the mining <br />operation by an unconfined aquifer that will be more permeable than the <br />overburden aquifer. In addition, the potential recharge capacity will be <br />greater in the mine plan area following reclamation. The increased recharge <br />capacity is not expected to have a significant impact on ground-water quantity <br />because only 5 percent of the Twentymile Park ground-water basin is recharged <br />from the affected area. The water discharged into the ground-water system <br />from the spoils aquifer will be higher in total dissolved solids and will be a <br />sulfate rather than the present bicarbonate type. This aquifer discharges <br />ultimately into Fish Creek. A state-of-the-art leaching study conducted by <br />Dr. Herbert Gardner (USDA, 1979) concluded that ground-water quality will <br />return to baseline conditions 74 years after reclamation is completed. <br />Similar information from the nearby Edna mine indicates that baseline <br />conditions will be reached 700 years after mining in an adjacent basin. <br />Because of this variable time period, OSM and the State requested that Energy <br />Fuels model solute transport to determine the decrease in water quality caused <br />by dissolved solids (primarily sulfate salts). The model showed that there <br />would be very little impact to ground-water quality in the Twentymile Park <br />ground rater basin, and that these impacts would lessen with time. In <br />addition, chemical analyses of the overburden and leaching tests performed on <br />the spoil indicate there are no toxic materials in the overburden. <br />Energy Fuels plans to open two box cuts at one year intervals. Water from the <br />overburden aquifer will be pumped from these box cuts at a maximum rate of <br />28,000 gallons per day during the second year of mining. Dewatering should be <br />• reduced to near zero in the fifth year of mining. The drawdown associated <br />with this pumping was projected and is not expected to be measurable more than <br />5,000 feet away from the box cut. Water pumped from the pits will be placed <br />in settling ponds to remove any sediment. Because dewatering is temporary, no <br />adverse impacts to ground-water quantity should occur. <br />Energy Fuels has installed 47 ground-water monitoring wells to detect changes <br />in ground rater levels and quality at the site and in the affected area. OSM <br />has determined that the company has enough wells to monitor any potential <br />effects of the proposed operation on the Twentymile Park ground-water basin. <br />OSMs analysis of the ground-water data submitted by Energy Fuels indicates <br />that there will be short-term effects to the ground-water system that include <br />increased postmining recharge rate, leaching of soluble ions in backfilled <br />areas, partial dewatering of the overburden aquifer, and temporary drawdown of <br />water levels in adjacent areas. The concentrations of dissolved solids will <br />be increased for a period of at least 74 years. This is not anticipated to be <br />a significant increase because of the dilution that will occur within the <br />Twentymile Park ground-water basin. The company owns enough senior water <br />rights in the general area to replace any water rights that might be injured <br />in the process of mining and have committed to this replacement in the mine <br />plan. Based on OSMs analysis, there will be no significant short- or <br />long-term environmental impacts to the ground-water system from the proposed <br />mining operation. <br />• <br />- 10 - <br />