The Yukon Supreme Court has approved a plan to clean up one of Yukon's abandoned mine sites, the contaminated Mount Nansen mine, 60 kilometres west of Carmacks.

The plan calls for the federal government to pay for the cleanup, but the mine site's court-appointed receiver, PricewaterhouseCoopers Inc., must first find qualified bidders who might agree to purchase the property and do the job.

As he approved the plan in Yukon Supreme Court on Friday, Chief Justice Ron Veale wondered aloud "how this was allowed to happen and why it's taken almost 20 years to fix it."

The Mount Nansen mine was abandoned in 1999 after the owner, Toronto firm BYG Natural Resources, was charged with numerous environmental violations.

Justice Veale was told it has cost taxpayers at least $25 million since then to monitor the site.

Owner will have 10 years to clean site

Now, after years of negotiation, the Little Salmon Carmacks First Nation, the Yukon Government and the federal government have endorsed a plan to sell the property to a qualified clean-up contractor.

The purchaser will be required to prepare a detailed design for the remediation plan, subject to peer review, and YESAA (Yukon Environmental and Socio-Economic Assessment Act) approval.

Required tasks include de-watering the Mount Nansen pit in preparation to accept 354,000 cubic metres of waste rock and more than 300,000 cubic metres of tailings and contaminated soil, then sealing the pit with a permanent liner.

The plan calls for a clean up "as close to walk away as possible," with nothing left on site that is not required for long term monitoring and maintenance.

The winning proponent will have up to 10 years to complete the tasks required, and could then acquire permits to mine any viable mineral deposits on the property.

Court was told experts who developed the plan have an idea what it might cost but won't speculate publicly, saying they don't want to prejudice the bidding process.

Justice Veale mused from the bench about the "lessons learned" from the process, and suggested an explanation is warranted for the time and expense involved. 

The Mount Nansen mine is one of four abandoned Yukon sites under federal government responsibility.