The owner of the Wolverine Mine has accepted the maximum possible fine following the 2010 collapse which killed a worker.

Meanwhile, the contractor involved insists it should be fined a lesser amount.

Both the mine's owner, Yukon Zinc Corp., and contractor Procon Mining and Tunnelling pleaded guilty to charges related to the collapse which killed 25-year-old Will Fisher.

In territorial court Tuesday, Yukon Zinc agreed to pay $150,000, the maximum amount possible in the Yukon.

Fisher, a mechanic and Procon employee, was buried under 70 tonnes of rocks early on the morning of April 25, 2010, about 190 km northwest of Watson Lake.

His body was recovered 10 hours later.

Fisher and two other employees were servicing a rock bolter, equipment used to install support in the walls and ceiling of the underground mine.

The two other employees were not seriously hurt.

During the night shift before the collapse occurred, water in the tunnel caused the ground beneath the bolter to become soft and the machine to get stuck, according to an agreed statement of facts between Yukon Zinc and the territory's director of occupational health and safety.

The soft ground had to be dug out.

"As a result of the mucking out, the floor of the slope was lower at the location where the ground fall occurred,” the statement says.

"Because of an earlier decision to vary the direction of the slope to follow the ore body, the width of the slope was increased.

"Thus, the dimensions of the slope at the location of the ground fall exceeded the recommended dimensions for the excavation.”

At the time of the collapse, the "back section of the rock bolter was located beside and under ground that was inadequately supported,” the statement says.

"The bolter was reinforcing unsupported ground at the face.”

At the time of Fisher's death, the determination of the direction the excavation was to take, was made by Yukon Zinc.

The company was also responsible for providing geotechnical support and a plan for ground support for the mine.

Yukon Zinc says it relied on Procon's safety program.

Any support was being installed based on a single-page diagram, as well as "an unwritten understanding that individual miners could install additional ground support if they felt it was needed,” the statement says.

"In practice, individual miners installed significantly more ground support than included in the diagram.”

Yukon Zinc admits that its practice was not consistent with recommendations in an earlier feasibility study or regulator requirements.

The mine now has an 87-page ground support plan signed by a geotechnical engineer certified in the Yukon.

An expert brought in after Fisher's death concluded that the mishap was caused by inadequate ground support, given that the tunnel had been widened and dug out.

Ground support decisions should have been made by a professional engineer or with the oversight of a professional engineer.

A second expert concluded that the safety program at the mine was not "robust or comprehensive enough for the type of operation or high hazard environment,” the agreed statement of facts reads.

This is not the first time an employee has died at the mine.

Six months before Fisher's death, 20-year-old Paul Wentzell, an apprentice mechanic with Procon, was crushed by a driverless Toyota Land Cruiser.

Procon pleaded guilty to two charges under the Occupational Health and Safety Act and was fined nearly $100,000.

In the six months before Fisher's death, there were three ground falls at the mine, the court heard.

According to the agreed statement of fact, after a ground fall on Feb. 7, 2010, Procon employees recommended the need for geotechnical expertise in their draft incident report.

"This draft incident report was received, reviewed and commented on by Yukon Zinc. No reviews or changes to the mining practices or safety program at Wolverine were implemented as a result of these ground falls.”

Judge John Faulkner will decide next week how much Procon will pay for its role in Fisher's death.

Lawyer Cindy Freedman, representing occupational heath and safety, is seeking the same fine for the contractor as Yukon Zinc received — $150,000.

She points to the three near-misses leading up to Fisher's death as signs that the safety program at the mine was inadequate.

But Procon's lawyer, James Sutherland, argued his client's employees were just "foot soldiers” in the operation.

Yukon Zinc was responsible for geotechnical support and ground support plans, he said.

The only thing Procon could have done with its concerns was stop work, Sutherland said.

But the company was reluctant to do that because ground support plans were not its area of expertise.

Stopping work would have meant shutting down the mine, which had 331 employees at the time, he said.

Looking back, halting work would have been the right choice, he said.

Sutherland insists the company is not hiding behind Yukon Zinc, but was trusting a company with more knowledge.

It should have been more assertive, but its mistakes were not deliberate, he said.

He suggests a $100,000 fine would be more appropriate in Procon's case.

After Fisher's death, the company spent more than $1 million to improve its safety program, he said.

A $100,000 fine is a sufficient deterrent which also sends a message that the company's positive steps have been acknowledged, he said.

Faulkner is scheduled to make his ruling Nov. 20.