Diavik hits ‘significant’ reclamation step, begins filling open pits

Diavik Diamond Mine announced Thursday it has been filling three open pits over the last several weeks with water from Lac de Gras, following the removal of mining equipment.

A news release described the filling of pits A21, A418, and A154 as a “significant step in the site’s reclamation,” saying that work is expected to take six to 12 months.

“We are very pleased to have reached this milestone in the progressive reclamation of Diavik,” Gord Stephenson, the mine’s general manager, was quoted as saying.

“Our goal is to leave the mine site in a safe and stable state and taking this step towards reconnecting our mine pits to Lac de Gras brings us closer to that goal.”

The mine said nine siphons can fill the pits at a rate of up to 850 litres of water flow per second, but how much water flows through the siphons will depend on the water levels in Lac de Gras.

There are also fish screens on the siphons to protect fish and limit their impact on wildlife.

The open pits will only be reconnected to Lac de Gras once water quality meets “acceptable criteria,” Diavik said.

The mine said it is developing a Trigger Action Response Plan to ensure filling the pits does not negatively impact water levels or quality.

Diavik also said traditional knowledge monitors visited mine site to observe the mine’s closure operations, including the pit filling process.

The mine ended commercial production earlier this year.

Active closure work at Diavik is expected to be completed by 2030, followed by a monitoring period that could last into the 2040s before Rio Tinto relinquishes the site.

“Diavik remains on schedule to complete active closure activities by 2030,” the news release said.