2nd De Beers Snap Lake dissolved solid limit increase OK'd by N.W.T. board

De Beers Canada is one step closer to solving a costly operational challenge at its Snap Lake diamond mine by getting its water licence amended.

Board decision says diamond mine's closure 'undesirable'

De Beers Canada is one step closer to solving a costly operational challenge at its Snap Lake diamond mine by getting its water licence amended.

The Mackenzie Valley Land and Water Board has recommended that the limit for total dissolved solids (TDS), including chloride, in Snap Lake be increased to 1,000 milligrams per litre for the rest of the mine's life.

Tom Ormsby, De Beers' director of external and corporate affairs in Canada, said the company is happy with the decision by the Mackenzie Valley Land and Water Board. (CBC)

The current limit, raised two months ago, is 684 milligrams per litre.

"De Beers welcomes the decision," said Tom Ormsby, De Beers' director of external and corporate affairs in Canada, via email. 

"The board's recommended conditions appear to be achievable, appropriate, and protective of the environment."

De Beers was seeking the added increase because the company has encountered a larger than expected amount of TDS-rich groundwater at the mine, located 220 kilometres northeast of Yellowknife.

Water being stored

The company pumps, treats and releases that water into Snap Lake, but it has also stored some of that water underground, at a cost of at least $20 million, to avoid going over the current TDS limit.

The result? De Beers can't mine everywhere it wants to at Snap Lake.

"Mining has become difficult, and we've seen a significant decline in our production reserve," Glen Koropchuk, De Beers' chief operating officer in Canada, told the board in March.

The board's recommendation — if approved by N.W.T. Environment Minister Michael Miltenberger — should give the company some breathing room. It may also allay fears about the 800-person mine closing early, something De Beers has pointed to as a possibility if the TDS limit is not raised to the level the company is seeking.

The board acknowledged the potential economic impact of Snap Lake's closing played a hand in its decision.

"This is an undesirable result given the many economic benefits of the mine to date, as well as those benefits that will continue to be realized by the people of the Northwest Territories if the mine is able to continue operating until...2026-2028," it wrote.

Water taste will likely change

According to De Beers, 300 of Snap Lake's employees are from the N.W.T. But the board's recommendation was based on more than just economic considerations.

The board said that though zooplankton might see some minor effects, "there is no evidence that there will be any direct effects on fish or any unsustainable effects to the aquatic ecosystem."

The board also said that though the taste of the water from Snap Lake will likely change, "there is no evidence that this will result in additional impacts to traditional users of the land in that area."

The board pointed to evidence from De Beers stating that, within seven years of the mine closing, "TDS concentrations in Snap Lake are predicted to decrease back to levels below esthetic guidelines for taste."

Just because it's upping the TDS limit for Snap Lake doesn't mean that will be the limit for other lakes, the board added.

De Beers will have to report to the board on a quarterly basis about the results of its treating the mine water using reverse osmosis.

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