Landslides near dam expected: Nalcor

Says North Spur will be well-stabilized before work is complete

James McLeod
Published on August 23, 2014
Gilbert Bennett, Nalcor’s vice-president in charge of the Muskrat Falls project. — Telegram File photo

Nalcor Energy wants people to know there will be more landslides around Muskrat Falls, and that it’s not a big deal.

In July, there was a landslide on the Churchill River downstream of Muskrat Falls, sending clay hundreds of metres out into the river.

The slide was about five kilometres from the falls, but it fuelled concerns among critics of the Muskrat Falls project — particularly a small number of people focused on the North Spur, at the site where the dam is being built.

The North Spur is a piece of land jutting out into the river which will essentially form part of the dam once Muskrat Falls is fully built. It’s partially made of something called “quick clay” and critics worry that once the dam is complete, the spur is liable to collapse.

 Nalcor isn’t worried. Gilbert Bennett, Nalcor’s vice-president in charge of the Muskrat Falls project, said they’re totally confident the July landslide had nothing to do with the work at Muskrat Falls.

“Five kilometres away is a long distance away,” Bennett said. “If we look at the conditions upstream and downstream, we know that those slides have happened at multiple locations, and we’re not too interested in those. They’re going to continue to happen.”

Following the landslide, The Telegram filed an access to information request for all briefing materials provided to Bennett and Nalcor CEO Ed Martin about the situation.

Nobody had emailed Martin about the issue and the handful of emails in Bennett’s inbox were largely dealing with media requests for information following the slide.

This week, Bennett sat down with The Telegram to explain why Nalcor is confident that the North Spur is not a cause for concern.

The plan involves flattening the spur by taking material off the top and adding material at the bottom, so that its steep sides are less likely to calve off into landslides.

Nalcor will also pile rocks at the base of the spur — essentially building a breakwater — both upstream and downstream of the Muskrat Falls dam to prevent waves from eroding it.

On top of that, the construction work at Muskrat Falls involves building a concrete and bromite wall in the ground along the length of the North Spur, which will extend 45 metres below the water level.

That wall will prevent water from slowly migrating through the spur from the reservoir upstream.

In one of the emails to Bennett following the landslide, Nalcor’s lead geotechnical engineer, Regis Bouchard, said that the North Spur is a unique case and there’s nothing exactly comparable to it anywhere in the world.

However, Bouchard pointed out that each of the measures being taken is proven technology which has been used elsewhere.

Bennett said it’s disappointing that people are so focused on the North Spur.

“It’s unfortunate. A small number of very vocal people have fixated on this issue,” he said.

Bennett said the North Spur has been studied since the 1960s, when Muskrat Falls was first identified as a potential hydroelectric resource.

Since 1970, there have been wells in place on the North Spur pumping water out, to keep the clay dry and shore it up.

More recently, the Muskrat Falls  engineer assigned to provide independent project oversight looked at the North Spur plans and concluded that they meet currently accepted geotechnical standards, and should stabilize the spur when Muskrat Falls is built.

Twitter: TelegramJames