Hearings into Diavik's dumping plans expected at end of July

Public hearings into the Diavik mine's plans to dump mine waste into old pits will take place this summer.

The Mackenzie Valley Environmental Impact Review Board will conduct at least two days of hearings at the end of July as part of its full assessment of the diamond mine's proposal.

"We haven't set the location yet. Probably there would be at least some of the hearings in Yellowknife or within driving distance in Behchoko," said Brett Wheler, senior environmental assessment policy adviser with the board.

He says groups and individuals can formally register to be part of the assessment and the hearings by submitting their concerns in writing now. There will also be time set aside for members of the public to walk in and have their say.

Diavik Diamond Mines Inc., the mine's operator, currently dumps processed kimberlite and a type of tailings known as slimes into a lined and dammed area at Lac de Gras, 300 kilometres northeast of Yellowknife. The tailings are more than 40 metres deep and the dam's walls have been extended six times to increase capacity.

The company says that storage area will be full by 2021 and will not last until the mine is set to close in 2025. It asked the Wek'eezhii Land and Water Board last year for a change in its water licence that would allow it to dump the waste into three mined-out pits. Diavik says that's a cheaper, safer alternative to above-ground storage.

Request triggered full review

The request has prompted a full environmental assessment because it is a radical departure from the way the mine had agreed to dispose of the waste when it was approved for development.

Processed kimberlite tailings, which range in consistency from fine dust to a toothpaste-like slurry that can act like quicksand, were to remain above ground. Interim closure plans are to cover them with a strong synthetic material that would be held down by waste rock.

The review board says depositing the waste into pits would be permanent and irreversible and could jeopardize the approved plan to reconnect the pit lakes to Lac de Gras after the mine closes. Right now, the pits are separated from Lac de Gras by dikes, which would come down after the mine stops operating.

Restoring the pits to productive fish habitat within Lac de Gras was part of the Canadian Environmental Assessment Agency's decision when it approved the mine for development in 1999.

Lac de Gras is the headwaters of the Coppermine River, which flows 520 kilometres north to the Arctic Ocean.

"Monitoring water quality to meet approved environmental standards is a key aspect of this application," Diavik says in a written statement to CBC North.

"Diavik Diamond Mines welcomes the opportunity for input from community members and expert review of the environmental assessment for this proposal," the statement reads.

The Mackenzie Valley Environmental Impact Review Board says its assessment will look at the potential impacts of Diavik's proposed activities on water quality and quantity; cultural use of the area; fish and fish habitat; and other wildlife — specifically caribou, aquatic and migratory birds, and species at risk.

The board aims to file its decision and report this fall. The N.W.T. minister of lands will then have five months to review it and consult with all other responsible ministers before giving a decision. After that, Diavik's water licence application will revert back to the Wek'eezhii Land and Water Board.