Remediation, closure activities underway at abandoned Minto mine, Yukon government says
CBC
The Yukon government is in the first phase of closing and remediating the abandoned Minto mine.
Officials with the Department of Energy, Mines and Resources said during a technical briefing on Sept. 28 that contractors are removing equipment and other infrastructure from the underground portion of the mine, after which pumps will be removed and the space will be allowed to naturally flood.
It's a common closure and remediation practice, said Darren Stahl, director of assessment and abandoned mines.
"It's been done at Keno mine — it's been flooded and dewatered several times over its life," he said.
The water, according to Stahl, will remain contained in the underground space, which has a capacity of approximately one million cubic metres or the equivalent of 400 Olympic-size swimming pools. It won't overflow due to the water table in the area, and also isn't expected to contaminate that water table or the surrounding soil.
The flooding is set to begin in November.
Longer-term reclamation plans include placing unwanted surface material into two above-ground pits that also have water in them and, when the water hits a certain level, having it flow down an engineered channel to a treatment plant before releasing it into Minto Creek. As well, crews will need to cover waste-rock piles with a top-coat that vegetation can grow on and do other landscaping to return the site to a more natural state.
The reclamation and closure work is happening as receiver PriceWaterhouseCoopers is soliciting bids for the mine, which the now-defunct Minto Metals Corp. suddenly abandoned on May 12.
The Yukon government took over the site the next day.
Stephen Mead, the assistant deputy minister of mineral resources and geoscience services, said that while the government knew at the time that Minto needed to expand its operations to remain profitable, it had "absolutely no warning" that the company would leave.
"People, sort of, I think, perhaps are rightfully skeptical… But being the person in the room when that call came in, it was a complete surprise and we spent the rest of that first day on the phone trying to mobilize resources," he said.
Mead said it took several weeks to make sure the site's "daily needs" were taken care of, particularly with the heavy spring melt. By July though, he said the government and Selkirk First Nation, on whose land the mine sits on, were in a position to plan for the site's future.
On top of wanting to protect the environment, Mead said the decision to start closure and reclamation activities was influenced by how another recent mine abandonment played out.
"I mean, the lesson from Wolverine is that we act quickly," he said, referring to a mine in southeast Yukon that its owner gradually let fall into disrepair, forcing the territorial government to step in when its underground flooded and overflowed in 2017.