Victoria Gold's Eagle gold mine site, north of Mayo, Y.T., in this handout aerial photo taken July 3. Giant piles of cyanide-laced rocks collapsed June 24 at a heap leach facility at the Eagle mine operated by Victoria Gold Corp., triggering a huge landslide.HO/The Canadian Press
Significant levels of cyanide threatening fish populations have been detected in a water body downstream of a gold mine in Yukon that experienced a devastating heap-leach failure late last month.
Giant piles of cyanide-laced rocks collapsed June 24 at a heap-leach facility at the Eagle mine operated by Victoria Gold Corp. VGCX-T, triggering a massive landslide.
Up until Thursday, it was unknown how much cyanide had escaped the containment area, and how much the environment was threatened.
At a technical briefing on Thursday, John Streicker, Yukon’s Minister of Energy, Mines and Resources, said early testing had revealed “elevated levels” of cyanide at Haggart Creek, which is downstream of the mine. Permitted levels of cyanide are no more than 0.005 milligrams per litre, but 0.04 milligrams per litre was detected there.
The high cyanide levels mean fish populations are at risk. Toxicity tests are under way.
Mr. Streicker cautioned that much more testing is necessary to ascertain the true extent of the cyanide contamination.
“This is a serious and significant slide,” he said. “Over time, we will need to do a lot of monitoring to understand how, where and when those potential contaminants are moving through either the surface or the groundwater.”
Geotechnical engineer Mark Smith said further landslides could lead to more damage to mine infrastructure and additional leaching of cyanide into the environment, especially considering that around 100 millimetres of rain typically falls in both July and August at the mine site.
“That’s enough rainfall to make me worried,” he said.
He pointed to one extremely steep slope on the heap measuring between 50 and 60 metres in height.
“It’s too steep to be stable, he said. “That slope will come down. It will either come down in a big rainstorm, or we will find some way to safely bring it down.”
The original landslide measured 1½ kilometres in length and contained four million tonnes of material. Half of that, or two million tonnes, escaped the containment area, with roughly 300,000 cubic metres of solution containing cyanide seeping into the environment, according to Mr. Smith, who attended the Yukon government’s briefing on Thursday.
Wildfire activity in Yukon is complicating the efforts of both Yukon workers and Victoria Gold’s staff as they work to mitigate the damage. Fires have already set back efforts to gather more water samples, and reduced the number of essential personnel permitted on the mine site to roughly 60.
Victoria Gold had more than $230-million in debt at the end of March, and was holding only about $27.7-million in cash. The company currently has no cash flow as it halted its production after the landslide occurred. On Thursday, the company said it had received notices of default from its lenders.
The cost to fix the catastrophe is unknown, and may ultimately fall on the Yukon government. The territory holds surety bonds worth $103.7-million that are supposed to be used to reclaim and rehabilitate the site in the event the mine’s owner doesn’t have the financial wherewithal to do so.
The government has said the bonds are equivalent to cash and that there’s no chance it won’t get paid. But the funds were supposed to be used for a site that is in a normal end-of-mine state, and not the location of a landslide that now requires a massive cleanup effort.
The Eagle mine is located about 375 kilometres north of Whitehorse and 85 kilometres north of the village of Mayo, on the traditional territory of the First Nation of Na-Cho Nyak Dun.
The First Nation on Wednesday called for a stop to all mining activity in its traditional territory, saying all of the focus should be on the cleanup effort at the Eagle mine. For generations, Na-Cho Nyak Dun members have hunted, trapped and fished in the vicinity of the mine.
Mr. Streicker on Thursday in the briefing indicated he had no intention of halting mining in the territory.
Editor’s note: An earlier version of this story used an incorrect measure, cubic litres, in reference to the size of the spill of cyanide solution. The correct measure is cubic metres. This version has been corrected.