British Columbia Mine Reclamation Symposium

Giant Mine remediation project Wells, C.


Following the discovery of gold in the Yellowknife, Northwest Territories, Canada, area in the 1930s, Giant Mine officially opened in 1948. Gold at Giant Mine was found locked in minerals, which needed to be roasted at extremely high temperatures. Unfortunately, this roasting process also released gases with a highly toxic by-product, arsenic trioxide. Throughout the 1950s, controls were put in place that minimised emissions to the air; however, this also resulted in the collection of 237,000 tonnes of highly toxic arsenic trioxide dust. At the time, scientists and government agencies agreed that storing the waste in underground stopes and chambers was an appropriate long-term management alternative. When ore processing ceased in 1999, the care and control of the mine fell to the Department of Aboriginal Affairs and Northern Development Canada, and attention was focused on the environmental issues left behind, including the arsenic trioxide stored in underground chambers. The Giant Mine remediation project was created in 2005 with the overall goal to protect human health and safety, and the environment. To do so requires the long-term containment and management of the arsenic trioxide waste, ongoing water treatment and clean-up of the surface elements of the site. The main objectives of the Giant Mine remediation project are to minimise risks to public and worker health and safety, minimise the release of contaminants from the site to the surrounding environment, remediate the site in a manner that encourages public confidence, and implement an approach that is cost-effective and robust over the long term. The project has recently completed an environmental assessment process under the Mackenzie Valley Resource Management Act, the governing legislation in the Northwest Territories for projects with the potential to have an impact on land or water. The project team is now proceeding with a clearly defined list of requirements established through the process of the project, but faces many challenges going forward, including technical considerations, regulatory and jurisdictional constraints, consultation and engagement requirements and resource pressures. It will require a great deal of ingenuity, planning and collaboration to address these challenges and deliver a successful project for the remediation of the Giant Mine site.

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