Yukon Zinc Corporation is staying mum about a cave-in that occurred inside the Wolverine mine last month.
Nobody was hurt by the collapse, which occurred between work shifts, sometime between 6 p.m. on February 15 and 6 a.m. on February 16, said Kurt Dieckmann with the Yukon Workers’ Compensation Health and Safety Board.
Workers were preparing to reinforce a section of tunnel with additional ground supports. When the next shift returned to the scene, they found a scissor lift partially buried by 500 tonnes of rock.
Yet the company did nothing wrong, as far as the board can tell, said Dieckmann. It was bolstering the tunnel supports to comply with stricter standards, introduced after a cave-in killed a 25-year-old mechanic in April of last year.
It appears that the scissor lift was parked on the edge of newly reinforced ground, and that caved-in rock “hit the front of the scissor lift and piled on top,” said Dieckmann.
It’s hard to say whether a worker would have been injured if the cave-in had occurred earlier, he said. “If someone was on it, it’s really hard to speculate whether they would have bailed off the back of it.”
Underground workers always ensure they’re standing beneath a properly reinforced tunnel, said Dieckmann, who spent two decades as an underground miner and has seen his share of tunnel collapses.
“You always work from good ground to bad ground. You don’t just drive under the bad ground and try to support it. You’d just never do that.”
The wet, crumbly rock inside Wolverine is held together with metre-long spikes, wire mesh and sprayed concrete. Miners upgrade tunnels with the help of far-reaching equipment.
Bolting machines, drills and shotcrete nozzles are all designed to reach shaky terrain while the operator stands under a stabilized tunnel.
Two men have died from accidents inside Wolverine. The first fatality occurred in October of 2009, when a 20-year-old apprentice was crushed by a Toyota Land Cruiser that rolled downhill after one of its emergency brakes failed.
The zinc, silver, copper and lead mine is located 190 kilometres northwest of Watson Lake. In the autumn it began sending its first shipments of ore to Stewart, BC, where it was then shipped to Asia.
Yukon Zinc Corporation, which is privately held by Chinese backers, declined to comment.
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