Aquifer restoration at uranium in situ leach sites
In situ mining of uranium involves injection of a leaching solution (lixiviant) into an ore-bearing aquifer. Frequently, the ground water in the mined aquifer is a domestic or livestock water supply. As the lixiviant migrates through the ore body, uranium and various associated elements such as arsenic, selenium, molybdenum, vanadium and radium-226 are mobilized in the ground water. Aquifer restoration after in situ mining is not fully understood. Several methods have been developed to restore mined aquifers to pre-mining (baseline) quality. Commonly used methods include ground water sweeping, clean water injection, and treatment by ion exchange and reverse osmosis technologies.
Ammonium carbonate lixiviant was used at one R&D in situ mine. Attempts were made to restore the aquifer using a variety of methods. Efforts were successful in reducing concentrations of the majority of contaminants to baseline levels. Concentrations of certain parameters, however, remained at levels above baseline six months after restoration ceased. Relatively large quantitites of ground water were processed in the restoration attempt considering the small size of the project (1.25 acre). More thorough characterization of the hydrogeology of the site may have enhanced the effectiveness of restoration and reduced potential environmental impacts associated with the project.
This paper presents some of the findings of a research project conducted by the Mineral Resources Waste Management Team at the University of Idaho in Moscow, Idaho. Views contained herein do not reflect U.S. Nuclear Regulatory Commission policy.
KeywordsUranium Ground Water Total Dissolve Solid Nuclear Regulatory Commission Vertical Hydraulic Conductivity
Unable to display preview. Download preview PDF.
- Anastasi, Frank S., 1984, An Analysis of Excursions and Hydrogeologic Testing Methods at Four In Situ Uranium Mines, Unpublished Master's Thesis, University of Idaho, 191 p.Google Scholar
- Hantush, M.S., and Jacob, C.E., 1955, Nonsteady Radial Flow in an Infinite Leaky Aquifer, Trans. Am. Geophys. Union, Vol. 36, No. 1, p. 93–100.Google Scholar
- Neuman, S.P., 1972, Field Determination of the Hydraulic Properties of Leaky Multiple Aquifer Systems, Water-Resources Res., Vol. 8, No. 5, p. 1284–1298.Google Scholar
- Weeks, E.P., 1969, Determining the Ratio of Horizontal to Vertical Permeability by Aquifer-Test Analysis, Water-Resources Res., Vol. 5, No. 1, p. 196–214.Google Scholar
- Williams, R.E., Osiensky, J.L., Anastasi, F.S. and Rogness, D., 1984, An Analysis of Excursions and Hydrogeologic Testing Methods at Selected Uranium Leach Sites in Wyoming and Texas, Draft Completion Report for Oak Ridge National Laboratory, Contract No. 7949.Google Scholar