Fifty Years Environmental Record at Elliot Lake

Abstract

Rio Algom Limited carries out care and maintenance of their uranium properties in the Elliot Lake area that were decommissioned and reclaimed during the 1990s. This included 10 underground mines, 8 metallurgical plants and 7 tailings areas. These historic mines were first developed in the mid-1950s to supply uranium to the United States and Britain for defence through Eldorado Mining and Refining. Seven were shut down by the early 1960s when the United States did not renew the contracts and did not reopen. Quirke, Panel and Stanleigh re-opened in the early 1980s to supply uranium for nuclear power plants. Stanleigh, the last operating mine, closed in 1996. Decommissioning and reclamation proposals were prepared for all sites and environmental assessments were completed for all of the properties in the late 1980s and 1990s. The decommissioning plans included the demolition of all surface facilities, sealing of the mine openings, and reclamation of the sites. The mine and mill sites were cleaned up, contoured and vegetated. Reclamation options were reviewed for each tailings area with the final closure plans including the flooding of 4 tailings areas, the covering and vegetation of 2 tailings areas and direct vegetation of 1 tailings area. In all cases, dams were either built or upgraded to meet Canadian Dam Safety Guidelines. Acid mine drainage has been curtailed at all of the flooded tailings areas with effluent treatment limited to polishing for radium 226 removal. The covered and vegetated sites are physically stable but continue to produce acidity which is treated at 2 lime treatment plants. The environmental assessments projected that for the selected reclamation plans, the area's ecology can be effectively protected, and that there are no impediments to the restoration of the entire Serpent River Watershed. Environmental monitoring has shown that the reclaimed sites are performing as expected, and that healthy aquatic communities are present in all major waterways in the region. This paper will describe the reclamation activities and environmental changes over the 50 years since the mines were first opened.