Factors Affecting Efficient Aquifer Restoration at In Situ Uranium Mine Sites |
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| Authors: | James L Osiensky Roy E Williams |
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| Institution: | James L. Osiensky is an associate professor of hydrogeology in the College of Mines and Earth Resources at the University of Idaho. He currently is located in the Department of Geology and Geophysics at Boise State University in Boise, Idaho (Department of Geology and Geophysics, Boise State University, Boise, ID 83725) as a part of a cooperative agreement between the two universities. Osiensky was an investigator in a project to analyze the hydrogeologic and hydrochemical factors that control excursions from in situ mining facilities.;Roy E. Williams is professor of hydrogeology in the College of Mines and Earth Resources at the University of Idaho (College of Mines and Earth Resources, University of Idaho, Moscow, ID 83843). His responsibilities include directing the research of graduate students and conducting research on mine hydrology, mineral resource waste management, and related ground water problems. From 1972 to 1974, Dr. Williams served on Intergovernmental Agency Personnel Exchange Act appointment with the U.S. Bureau of Mines in Washington, D.C. From 1978 to 1980, he was director of the Idaho Mining and Mineral Resources Research Institute. Aside from these four years, Dr. Williams has been connected with the hydrogeology program at the University of Idaho in several capacities. He is an advisor to several federal and state agencies on ground water contamination and waste management. |
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| Abstract: | In situ mining of uranium typically requires the injection of a reactive leaching solution (lixiviant) such as sodium carbonate/bicarbonate, ammonium carbonate/bicarbonate, or sulfuric acid, and an oxidant such as hydrogen peroxide or oxygen into an ore-bearing, confined aquifer. It also requires the environmental restoration of the source aquifer. The stratigraphy of sandstone uranium deposits typically consists of interbedded layers of poorly consolidated sands and clays and gravels deposited in fluvial or coastal environments. The parameters that influence the migration of lixiviant during mining and restoration in these environments include induced hydraulic gradients, hydrodynamic dispersion, heterogeneity, anisotropy, physicochemical reactions, leakage into and/or through confining layers, and convergence of flow lines due to partial well penetration.
The effectiveness of the various methods of aquifer restoration is sit -specific and is dependent upon the site hydrogeology and hydrogeochemistry, and the chemistry of the lixiviant. Each method of aquifer restoration has advantages and disadvantages. Selection of the most effective and economically feasible method requires detailed knowledge of the site-specific hydrogeologic conditions. |
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