Cleaning up Giant Mine will take longer and cost much more than planned

The Giant Mine remediation site with Yellowknife in the distance. Ollie Williams/Cabin Radio

Work to clean up Yellowknife’s Giant Mine will take at least seven years longer than initially planned and cost significantly more than the $1 billion already budgeted.

Officials on Wednesday stated active remediation at the toxic former gold mine will now take until at least 2038 instead of 2031. The delay had already been outlined in broader terms earlier in the year.

The federally led remediation project team says the extension is necessary partly because more work is required than originally planned and partly to avoid overwhelming northern contractors, especially as businesses in the NWT struggle to attract workers during a labour shortage.

“It seems like a long time but there is a lot of work to be done,” said Brad Thompson, regional project advisor for major projects at Public Services and Procurement Canada.



“What we didn’t appreciate are just the interdependencies, how one thing affects the other. We want to have a realistic schedule.

“We want to make sure northern businesses have the capacity to do this [and receive] maximum opportunities from what we’re doing.”

The current budget for remediation, $934 million, dates back to 2014. Officials said they had waited until now to update that estimate because the project’s scope had to be broadened after an earlier environmental assessment. Even figuring out how much work is required has taken years, while the work already completed has produced more waste than expected.

The new cost estimate is being kept secret until the federal treasury board considers it at a meeting currently scheduled for October 27. The project does not expect its new, larger budget request to be denied, adding recent inflation is also a factor.



“I would say the government appreciates the importance of this project,” said Thompson.

Employment to peak in 2031

In many respects, Ottawa doesn’t have a choice.

Giant Mine, which operated from the 1940s until abandonment in 2005, sits on 237,000 tonnes of toxic arsenic trioxide.

The federal and territorial governments have no real option but to pay whatever it costs to contain that lethal mining byproduct in chambers below the mine. For now, the chosen method is freezing the arsenic trioxide in place using thermosyphons, which act like heat pumps to cool the rock around the chambers, freezing water around the rock and ensuring arsenic trioxide cannot leave.

Thermosyphons at Giant Mine. Ollie Williams/Cabin Radio
A reporter takes a photo in front of Giant Mine’s former mill in September 2022. Ollie Williams/Cabin Radio

Even once active remediation ends in the late 2030s, the thermosyphon system is essentially tasked with doing its work indefinitely until scientists devise a better solution. At the moment, moving the arsenic trioxide out of the underground chambers is considered too risky and there is no other realistic means of eliminating it.

While the taxpayer may not appreciate the extraordinary cost, a ballooning budget for the cleanup is not entirely bad news for the Northwest Territories.

The new, extended timeline is designed in part to ensure as much work as possible reaches northern and Indigenous businesses, following previous criticism that Giant’s economic benefits were not reaching enough local people.

On Wednesday, officials briefing reporters at the mine site said $313 million, around 48 percent of the contracts awarded since 2005, had been directed to Indigenous contractors.



Under the new plan, employment at the mine is set to peak in 2031, when the equivalent of around 260 full-time jobs will be available.

The remediation has in the past been likened to the opening of a new, small mine, such is the anticipated impact on employment in Yellowknife. The Yellowknives Dene First Nation is now receiving more than $1.5 million annually through various initiatives, officials said on Wednesday, though the First Nation is in the process of seeking formal compensation and an apology from the federal government for the mine’s lasting toxic impact, which has caused multiple deaths, ruined the surrounding environment, and occurred on Canada’s watch.

Bundled rock is seen in front of the former Giant Mine mill. Ollie Williams/Cabin Radio
An abandoned home on the former Giant Mine town site. Ollie Williams/Cabin Radio

Yet despite the money and jobs the remediation promises, the timeline extension announced on Wednesday also acknowledges the pressures on the city’s labour supply – and housing – if too many workers are needed at once, even though much of the remaining work is seasonal.

Even in the past few years, the work schedule for some projects – such as demolition of the 40 or so buildings that form the mine’s old town site – has slipped as challenges arise.

Those buildings are now due to come down in the spring of 2023.

Long boarded up, the deserted homes form a reminder that what is today a toxic burden was for decades Yellowknife’s lifeblood.

A man driving a busload of reporters around the site on Wednesday pointed to one of the homes, second from the end of a lakeside road. He had lived there in the 1990s.

Work still to come

Another major project expected in 2023 is construction of a year-round water treatment plant, which will allow the cleanup team to stop storing water on-site for much of each year, in turn hastening the speed at which the site can be remediated.



A lot of the work still to come involves, at least in part, managing water and reducing the risk contamination of that water might pose.

An assortment of other projects will involve cleanup of waste rock and open pits, filling in underground voids using a cement backfill to keep the surface stable, and even remediating the likes of roads, bridges and fences.

But the primary focus will be installation of 858 thermosyphons to achieve the main objective of keeping the underground rock at -5C year-round, freezing the arsenic trioxide in place.

If water gets close to that cooled rock, said Thompson, “it freezes and creates a shell around there, so water can never touch or mobilize the arsenic trioxide.”

The system has already been tested at the site. Work to deploy the first 250 or so thermosyphons is under way.

The bulk of that work is expected to take a decade, beginning in 2025.

Brad Thompson rides through the Giant Mine site on a tour for reporters in September 2022. Ollie Williams/Cabin Radio
Hundreds of seacans containing contaminated material at Giant Mine. Ollie Williams/Cabin Radio
Hundreds of seacans containing highly contaminated material at Giant Mine. Ollie Williams/Cabin Radio

The scale of contamination at the site is immense.

Though workers have been here for years and full-scale remediation began last year, one reporter on Wednesday’s site tour summed up the task ahead in stating to a colleague: “Everywhere you look, there’s crap.”



In one section of the site, hundreds of neatly aligned seacans each contain parts from the mine’s roaster, a gold separation facility once considered the most contaminated building in Canada.

When the time comes, the material inside every seacan will be placed into an old open pit at Giant, buried, and frozen just like the arsenic trioxide, locking the toxic building’s bones underground – essentially forever.

The project team is still figuring out what to do with hundreds of empty, highly contaminated seacans after that.

Elsewhere, a landfill currently being built will hold some 96,000 cubic metres of non-hazardous waste like wood and metal as buildings are deconstructed (asbestos, decidedly more hazardous, will be specially contained in a segregated area of that landfill). A further 84,000 cubic metres of waste will be held in a sludge pool next door.

Hazardous material is handed over to environmental firm KBL, which ordinarily ships such waste out of the territory to the south.