Diavik outlines next steps in mine closure at Yellowknife town hall

Diavik diamond mine managers say its closure remains on schedule, with major reclamation work expected to wrap up by the end of 2028 and the company planning to leave the site by 2030.

Representatives provided an update during a Yellowknife town hall on Thursday evening, outlining progress since commercial diamond production ended in March after nearly 23 years. 

“We’re quite happy to be on track and on schedule with our closure timeline,” general manager Gord Stephenson told Cabin Radio. 

One of the largest projects under way is filling three open pits with water from Lac de Gras. 

Diavik began filling the pits in July, using nine siphons to transfer lake water into the former mining areas. 

Closure manager Sean Sinclair said that process is approximately 50-percent complete, with the pits expected to be filled this winter. 

Once filled, the water will be tested to ensure it meets environmental and cultural-use criteria before the pits can be reconnected to Lac de Gras. 

The company expects to begin breaching the dikes separating the pits from the lake next summer, provided water quality meets the required standards. 

Demolition is also under way, with several major buildings already removed, including the mine’s crusher and backfill plants and a powerhouse. 

Stephenson said demolition began a year earlier than originally planned, putting that work slightly ahead of schedule. 

Most reclamation work is expected to be completed by the end of 2028, with a final cleanup continuing into 2029. 

Diavik expects to leave the site by 2030, although environmental monitoring could continue until 2050 for some areas. 

Jobs and Rio Tinto’s future in Yellowknife

The closure is also bringing significant changes to employment in the Northwest Territories. 

During operations, Diavik employed 1,100 to 1,200 people. That number has fallen to around 400, with 150 to 200 workers on site at a time. 

“We do have pretty steady employment in the closure context through 2028 and then, after that, it will drop significantly as the works are wrapped up,” Stephenson said. 

Asked whether Rio Tinto intends to maintain a long-term presence in Yellowknife, Stephenson emphasized that the closure team is locally managed and the company will continue overseeing the site after active reclamation ends. 

“Active closure through 2029, and then Rio Tinto closure will continue to monitor and oversee the site through eventual relinquishment,” he said. 

However, he did not specify how many Yellowknife-based positions would remain in the longer term. 

Stephenson acknowledged the closure will have economic consequences for the territory, but said the company continues to prioritize northern hiring and spending during reclamation.

Environmental oversight and Frame Lake

Questions also remain about environmental oversight as Diavik moves toward long-term monitoring. 

Earlier this year, the NWT’s environment minister approved the wind-down of Diavik’s independent Environmental Monitoring Advisory Board, known as Emab, by March 31, 2027.

Sinclair said the board’s closure does not mean environmental regulation will end. 

“The wind-down of Emab does not mean Diavik won’t be regulated,” he told Cabin Radio.

He pointed to continued oversight by the Wek’èezhìı Land and Water Board and a traditional knowledge monitoring program involving Indigenous partners. 

That program began this year and is intended to complement scientific monitoring by allowing communities to assess reclamation through traditional knowledge and observation of the land. 

Diavik also provided an update on its Frame Lake aerator project, intended to improve conditions for fish in the Yellowknife lake.

Earlier this year, Diavik delayed plans to reintroduce fish to Frame Lake while reviewing monitoring data. 

Sinclair said the aerator will continue operating through a third winter, with some progress being observed.

“We are seeing progress in terms of the performance,” he said. 

However, fish reintroduction remains on hold, with another update expected next year. 

Residents reflect on Diavik’s legacy

Former Diavik employees were among those attending Thursday’s town hall.

Tom Hoefer, who worked at Diavik for approximately 11 years, said he was pleased to see the company following through on commitments made decades ago. 

“I know what we said we would do back in 1998, and I’m really glad to see – this many years later – that they’re doing what they said they would do,” he told Cabin Radio.

“I think it’s textbook. It’s the way mining should be done.”

Yellowknife city manager Stephen Van Dine also attended, saying Diavik had played an important role in the community and had outlined a comprehensive cleanup and monitoring plan.

During the town hall, Diavik presented one of its last rough diamonds to the Yellowknife Historical Society.

Sinclair said he hopes the closure will serve as an example for other mining operations. 

“We’re very hopeful that over the next couple of years, once we wrap up the active closure phase, we’ll be an example of a successfully closed mine,” he said.