Tundra Mine Remediation

History

Tundra Mine is a former gold mine located 240 km northeast of Yellowknife in the Northwest Territories. Mine operations began in 1964 and ceased in the mid-1980s. Tundra is one of three mines that reverted to the Government of Canada in 1999 when the owner, Royal Oak Mines Inc., went into receivership. This occurred before Canada implemented the Mine Site Reclamation Policy for the Northwest Territories. Implemented in 2002, this policy states that adequate security be provided by the operator of the mine to ensure the cost of reclamation in case of abandonment. The Government of Canada has therefore funded remediation of this site, as well as care and maintenance, from 1999 to present day.

This photo shows a flat area of rock and soil, separated by trees. Forest burnt by the 2014 forest fires is visible behind the structures.
 

Caption: This area has been cleared of ore residue called tailings. The tailings have been consolidated into an area that will be covered by a geomembrane liner and gravel. This engineered cap prevents contact with the tailings: fresh rain water flows over the gravel, separated from contaminates by the geomembrane liner.

Remediation Progress

1999Care and maintenance of the site included dam repairs, landfill repairs, geotechnical inspections of dams, water management and water quality monitoring.
2007Initial remediation was completed, including removal of buildings and hazardous waste, construction of a non-hazardous landfill, and capping of mine openings.
2009Water treatment was carried out on-site to treat the water in the Tailings Containment Area (TCA).
2010The contract for further remediation was awarded and water treatment of the TCA continued.
2011Full remediation of the site began in June 2011. This work included water treatment, excavation of hydrocarbon-contaminated soil and the consolidation of tailings solids and buried debris.
2012-2014Further remediation work occurred, including additional water treatment in the TCA, treating hydrocarbon-contaminated soil, covering tailings and waste rock, and decommissioning dams.
2014-2015In August 2014, the contractor informed the Government of Canada that it would be unable to complete the remediation contract. The Contract was terminated by mutual consent in April 2015. The site began to be managed through a care and maintenance contract in April 2015.
2016Care and maintenance activities at the site were completed and a Phase IIB remediation contract was tendered. Canada expects to award the remediation contract in the fall of 2016.
This image outlines the various sections of the Tundra Mine Remediation Site. From left to right: the lined portion of the Tailings Containment Area (TCA), the unlined portion of the TCA, the West Lower Pond Borrow Area, the water treatment plant, and the TCA cleared of tailings.
 

Caption: This diagram outlines the remediation activities at the Tundra Mine Remediation Site. To put the image in context, the Water Treatment Plant is roughly the size of 1.5 soccer fields.

More Information

The main concern at the site is the remediation of tailings and tailings-impacted water. These products have elevated levels of arsenic and other metals which could affect the downstream environment if left uncontrolled and untreated. Currently, all water runoff from the Tailings Containment Area is treated before being discharged into the environment. While approximately fifty percent of the engineered cap that will cover the tailings was completed in Phase II of remediation, the catchment area is enclosed and the discharged point is monitored during the open water season.

Future remediation activities include consolidating the remaining tailings, treating tailings-impacted water, completing the engineered cap, and excavating and treating hydrocarbon-impacted soils. If treated onsite, the contaminated soils must be treated to criteria set by the Mackenzie Valley Land and Water Board.

Finally, the West Lower Pond Borrow Area will be regraded to be more stable. A borrow area is similar to a quarry but does not require blasting. Regrading the borrow area will minimize the risk of erosion and sediment released to the environment.

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