Yukon mine poses environmental risk decades after being remediated under federal watch

Yukon’s government has been left to pay for the clean-up of a decommissioned mine that could leach toxic metals into Kluane River, raising questions about the federal government’s decision to let the owner walk away decades ago.

A nine-hectare tailings pond containing roughly 170,000 tonnes of tailings at the Wellgreen property, where rare earth metals such as copper, nickel and gold were mined in the 1970s, could be generating acid that reacts with metals in the tailings, making them toxic. This poses a risk to surface and groundwater in the area, as well as aquatic life.  

The mine site is made up of two leases, one of which is still being mined by Nickel Creek Platinum. The Yukon government issued an order in council in  2012 to block future staking  of the other parcel — containing an old tailings pond and mill previously used by Hudson Bay Mining — to prevent further environmental damage.

A portion of the Wellgreen Project site requires remediation to prevent toxic metals from potentially leaching into surrounding ground and surface water, while the other portion, seen here, is actively mined. Photo: mining.com / Flickr

Just who is tasked with cleaning up the site, which is located 27 kilometres northwest of Burwash Landing, harkens back to the transfer of power from the federal government to the territory in 2003 — known as devolution — which gave Yukon control over natural resources such as minerals. When this transfer happened, the site wasn’t classified as a Type II mine — an area deemed to pose significant liabilities that would be remediated with federal funding. Now that it has been deemed enough of an environmental liability to be a concern, the Yukon government and, by extension, Yukoners are on the hook for remediation. 

Paul Inglis, manager of the assessment remediation unit, a branch of Environment Yukon, said the clean-up tab could be $15 million based on recently contracted assessment work. According to the Yukon government’s contract registry, the territory has spent nearly $1 million related to inspection and reclamation work at the site over the past decade. 

“We’re not quite sure if the Yukon government is going to have to pay for the whole thing or if there’s going to be contributions from somewhere else,” Inglis said, noting that it’s unclear at this point where those other funds could come from.

“It needs to be cleaned up before it becomes an issue.”

Environmental concerns at the Wellgreen site 

There are three ingredients that make acid generation a very real prospect in the old Wellgreen tailings pond — sulphide, air and water, which, when they react, create acid. That acid then converts metals into a more active form that can pose a significant risk should it reach ground or surface water. 

“It’s those metals that are toxic to aquatic life,” Inglis said. 

Kluane River, home to fish such as chinook salmon and Arctic grayling, is roughly one kilometre east of the site. There’s a spillway from the tailings pond that leads to nearby Quill Creek, which drains into the Kluane River.

“We have the conditions that mean that, at some point, it’s likely that there would be acid generation into either the groundwater or surface water that flows over the tailings,” Inglis said. Though he added that it would be rare for surface water that comes into contact with tailings to reach the creek, as it usually dries up or goes into the ground before making it that far.

Wellgreen’s remediation history and why it still isn’t remediated

Hudson Bay Mining, now Hudbay Minerals, operated the Wellgreen mine until 1973, then the mill was shuttered and dismantled, leaving behind debris and thousands of tonnes of tailings. The company attempted to stabilize the site during the next three years by submerging the tailings and increasing the height of the tailings dam.

“The feds basically said make sure it’s covered by water and you’re good to go,” Inglis said. “It was effectively abandoned.”

While the company had met the standards of the day, it became clear that the plan wasn’t sufficient, with inflows not large enough to adequately cover the tailings pond with an even layer of water throughout the year, increasing the risk for acid generation, Inglis said. There’s also no liner on the tailings pond, he said, raising the possibility of metals leaching into groundwater.

The Wellgreen Project site is in southwest Yukon, near the Kluane National Park boundary. Photo: mining.com / Flickr

According to the remediation proposal, samples collected in the immediate area of the tailings pond had the highest concentration of metals, but those taken farther away, including in Quill Creek, had not been impacted by the metals. 

Nonetheless, seeing the risks, the Yukon government stepped in to complete remediation. While the predecessor of Hudbay Minerals — which remains in operation today with two mines in Canada and more abroad — had followed the rules, the rules have since changed, rendering the reclamation work inadequate.

Corporate responsibility and financial security

The Wellgreen property raises questions about how long companies are responsible for tidying up former operations, said Lewis Rifkind, mining analyst at the Yukon Conservation Society.

“Is there a legal responsibility or not? That doesn’t seem clear,” he said. “While I look at this through green goggles, old abandoned sites, when they become toxic hazards, you tend to go after whoever created the mess and ask them to clean it up. It’s an interesting legal question and it hasn’t been resolved.”

The undercurrent to this, Rifkind continued, is why this site wasn’t considered a Type II mine when devolution occurred. Rifkind pointed to the case of former asbestos mine Clinton Creek, which received Type II designation and in turn the funding attached to the  federal government’s Northern mine reclamation program. 

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“It seems unclear how sites are determined to be Type II,” Rifkind said, adding that the Wellgreen site appears to pose enough of an environmental risk to warrant giving it Type II status. Doing so, he said, would have insulated Yukoners from paying for its clean-up.

In a submission to the Yukon Mineral Development Strategy, an independent panel tasked with recommending improvements to the territory’s mining regime, Kluane First Nation says the Wellgreen site poses a risk to the environment and the nation’s traditional territory. The First Nation said that a long-term solution is needed to avoid repeat problems, including the potential for more unremediated mines to surface in the future.

The Yukon government “must implement a comprehensive system to deal with abandoned sites,” it says. “While Wellgreen is tied to the past and murky, future abandonment of sites will occur and [the Yukon government] must be prepared to address those issues with mechanisms such as increased security amounts.”

Chief Bob Dickson wasn’t immediately available for comment.

Where remediation of the Wellgreen property is at now 

The Yukon government’s remediation proposal, currently being assessed by the Yukon Environmental and Socio-economic Assessment Board, says the preferred clean-up option is  containing the tailings with a cover layered with clay and soil that will ultimately be revegetated, and using drainage ditches to divert surface water from the tailings area.  

But the project in front of the assessment board only accounts for 30 per cent of the remediation design, Inglis said. It will be the basis for continued work to fully reclaim the site.

Remediation work is slated to start in the spring of 2022, Inglis said.