Decommissioning and reclamation of the Beaverlodge mine/mill operations

After 30 years of nearly continuous mining at Beaverlodge, Saskatchewan, approximately 6 x 106 tonnes of uranium mill tailings had been deposited, using shallow lake disposal, in three natural lake basins. This paper discusses the engineering, environmental and radiological assessments undertaken by Eldorado Resources Limited to achieve an acceptable close-out plan. Since the tailings had been placed in natural lake basins, with exposed tailings deltas at each site, the choice of close-out concepts were limited to: water cover of all tailings to a nominal depth of 2 meters, vegetation, and physical cover. At one lake, removal of tailings with disposal underground was also evaluated. For each concept, realistic engineering options were selected in discussion with the regulatory agencies, and a feasibility study was conducted to determine methods and costs. An environmental data base was collected during the year prior to closure. These, together with routine water quality monitoring and meteorological data, were used to develop computer models to assess the close-out concepts from an environmental perspective. The data and model results also inputted into a pathways assessment of the concepts. ALARA optimization calculations were performed in order to aid in the selection of the preferred concept(s). In the end, the decision to reclaim the site was based on a code of practice which sought to minimize the migration of tailings through stabilization