The NWT’s Snap Lake diamond mine will be flooded next month, more than a year after it was placed on care and maintenance.

Owner De Beers says the move will help preserve the long-term viability of the ore body, reduce costs and help mitigate environmental risks.

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Flooding should take six to eight weeks to complete. Once the project wraps up, the company expects to let 20 staff go.

“Snap Lake currently employs 55 people,” said De Beers. “The workforce required once the flooding project is complete will be approximately 35 people.”

De Beers says employees who are displaced will be considered for other jobs within the company or provided with a severance package.

More than 400 people were laid off last December when Snap Lake was placed on care and maintenance.

However, a quarter of those people are now working at the territory’s Gahcho Kué diamond mine, which is also operated by De Beers.

Once Snap Lake is flooded, the company says the mine will enter a long-term phase of care and maintenance primarily focused on environmental monitoring activities.

“[This] will preserve the significant diamond mineral resource in the ground … until market conditions and improved technical methods make the kimberlite more economic to operate,” said De Beers.

The decision to flood Snap Lake was made after De Beers said it couldn’t find an external party to purchase the mine off them.

Meanwhile, production continues to ramp up at Gahcho Kué, with the mine expected to reach a commercial level of production in early 2017.