Some people believe the Carmacks Copper Project will leave behind a toxic mess.
The proponent, Western Copper, says that the site will be cleaned up and safe within four years of closure.
The Yukon Environmental and Socio-Economic Assessment Board has hired a consultant to sort out who’s right.
It’s nice to see the system working, said Gerry Couture of the Yukon Conservation Society.
“The board made a draft recommendation; they got some very serious comments on it, so they’re going back and looking at that recommendation and looking at the problems that the comments brought out,” he said.
“I look forward to seeing what they come up with.”
Western Copper Corporation has proposed an open-pit copper mine 38 kilometres northwest of Carmacks.
The proposed site is also nine kilometres west of the Yukon River.
To extract the copper, the corporation plans to use a technique known as acid heap leaching.
Crushed ore is piled up rubber liners and doused with acid.
This dissolves the copper out of the ore. It’s considered quick, easy and inexpensive.
The problem is that when the mine is finished, millions of tons of acid-laced ore will be left behind.
These toxic piles could continue to leach copper and other heavy metals into the ground for many years to come.
Western Copper proposes to rinse the heaps with water, and use a lime treatment to neutralize the acid.
Tests conducted by the company say that this treatment would allow the company to walk away from the site within four years.
However, information submitted by the Yukon Conservation Society suggests it might not be that easy.
Large-scale studies completed by Lionel Catalan of Lakehead University show that lime rinsing will not detoxify the heap.
Catalan’s study used five massive vats each containing 4,000 tonnes of copper oxide ore.
Western Copper’s study was conducted in a Vancouver laboratory, using 22.7-litre, plastic buckets.
The assessment board has asked Ron Nicholson, the senior environmental scientist at EcoMetrix Inc. to investigate the discrepancies between the two reports.
Nicholson has 25 years of experience in the mining industry and has worked with the Faro Mine cleanup.
He will review the documentation provided by the Western Copper, the Yukon government, Little Salmon Carmacks and the Yukon Conservation Society.
“We’ve asked him a couple of key questions,” said Stephen Mills, a member of the assessment board’s executive committee.
“Whether or not the heap can be detoxified as proposed by the proponent, and, if so, over what period of time.
“We’ve also asked him to answer some of the comments provided by the expert of the Conservation Society.”
The executive committee has 21 days to decide whether or not it requires more information from the proponent.
The second public comment period on the proposal ended on February 6, so a decision will have to be made by next February 27.
“We’re still concerned about the plan for that mine’s closure as it has been proposed,” said Couture.
“We’re looking forward to perhaps a recommendation that either something new will be done or that there’s some certainty that the closure will be safe.”
Contact Chris Oke at chriso@yukon-news.com