Giant Mine covers 949 hectares and is situated within the city limits of Yellowknife, NWT. The site lies along the western shore of Yellowknife Bay, an arm of Great Slave Lake. This gold mine operated nearly continuously from 1948 until its closure in July 1999.
The site includes 237,000 tonnes of arsenic trioxide stored underground, as well as various buildings and surface areas contaminated with arsenic. If not managed properly, these site risks represent significant hazards to human health and the environment.
A remediation plan was completed by the site following extensive site characterization and community consultations. The plan has now entered the Environmental Assessment process, pursuant to terms of reference issued by the Mackenzie Valley Environmental Impact Review Board in March 2009.
Care and maintenance of the site is ongoing in order to ensure compliance with the environmental provisions of the federal Fisheries Act. It is anticipated that the Environmental Assessment process could take up to three years to complete. The current cost of care and maintenance and project management (including the Environmental Assessment process) is estimated at $30,000/ day.
In the interim, a Freeze Optimization Study has been initiated and funded by Canada's Economic Action Plan (CEAP) to inform the EA and assist in the final design of the remediation project. Once the Environmental Assessment process has been completed, remediation activities are expected to take approximately eight years.
Under the terms of a 2005 Cooperation Agreement, AANDC and the Government of the NWT agreed to maximize northern economic development opportunities in carrying out the Giant Mine Remediation Project (subject to the policies and legislation of each government). These benefits are already being realized as a result of a decision to contract care and maintenance activities to Deton'Cho/Nuna, a Yellowknives Dene and northern company joint venture.