Casino considers new tailings pond design

The president of Casino Mining Corporation says the company is looking at a new design for its tailings pond that would reduce the amount of water behind the dam.

The president of Casino Mining Corporation says the company is looking at a new design for its tailings pond that would reduce the amount of water behind the dam.

Paul West-Sells said using less water should reduce the environmental impact of a spill. But he insisted that both the old and new designs have a “negligible” chance of failure.

“The design we had before was fine. It would have been sufficient,” he said. “However, the failure of that design has a reasonably significant impact on the environment.”

Concern about Casino’s tailings pond was one of the major reasons the Yukon Environmental and Socio-economic Assessment Board bumped the project to a panel review, the territory’s highest level of assessment, in February.

As originally proposed, the dam would have been the highest tailings dam in the world, and the pond would have covered 11 square kilometres. According to YESAB, a dam failure could have released tailings into the Donjek, White and Yukon rivers.

West-Sells wouldn’t provide many details about the new design, as the engineering isn’t complete. He also wouldn’t say whether the new design would reduce the height of the dam.

But he did say that dry stacked tailings, a technology that doesn’t require tailings ponds at all, is not an option for Casino.

“Unless there’s a new technology developed, there will always be a portion of the waste out of Casino that needs to be flooded,” he said. Otherwise, there would be a risk of a flow of acidic water from the tailings into the environment.

YESAB finalized a set of guidelines for the Casino panel review in June, which has been sent to the mining company. Those guidelines set out an extensive list of information the company must provide before YESAB convenes a panel to review the project. Casino must provide a timeline for its response by Aug. 19.

The guidelines include a requirement that Casino look at alternative methods for tailings disposal, including dry stacked tailings. The company must also analyze the possible impacts of a tailings dam failure.

West-Sells said that last requirement marks a change from what was asked of mining companies in the past.

Traditionally, he said, proponents just had to show that their tailings dams had a very low chance of failure. But since the Mount Polley tailings dam failed in August 2014 and spilled 25 million cubic metres of contaminated water and waste into B.C. waterways, companies have been asked to look more closely at the effects of a possible spill.

“We’re being forced by regulators to explore what a failure really looks like,” West-Sells said.

He said he plans to present the new tailings pond design to the Yukon public, likely before it’s even submitted to YESAB.

The Casino mine would be the largest in Yukon’s history. But West-Sells insists that it’s a “standard, off-the-shelf operation.”

He said the mine shouldn’t have a problem getting permitted, provided the company does a good job of communicating with the public.

“What’s important is that we work with the governments and the First Nations and … the people of the Yukon … and really make them understand what the project is and the advantages of the project,” he said.

He pointed out that Goldman Sachs recently calculated that the Casino mine would be economical at a copper price of US$2,061 per tonne. Given that copper is currently sitting at US$4,862 per tonne, that means the mine could be profitable today.

West-Sells said he’s not worried about having enough money to get through the panel review. He said the company has $9 million in the bank right now.

“We’re sufficiently financed. We’ve never had a challenge with raising money, and the market’s a bit better now,” he said.

West-Sells said he hopes to respond to the YESAB guidelines in the second half of 2017, meaning the panel review could start late next year or in early 2018.

Contact Maura Forrest at

maura.forrest@yukon-news.com

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