A controversial copper mining project has been recommended for approval.
The approval comes despite persistent concerns from environmental groups and First Nations that Western Copper Corporation’s ore piles will leach acids and heavy metals into the surrounding watershed long after the mine is gone.
The Yukon Environmental and Socio-economic Assessment Board released its 304-page report late Friday afternoon.
The report OK’d the project, but included several mitigating measures.
Western Copper wants to build an open pit copper mine 38 kilometres northwest of Carmacks.
The metal will be extracted using an inexpensive technique known as acid heap leaching.
Millions of tons of crushed ore will be piled onto rubber liners and doused with an acidic cocktail.
The toxic solution dissolves the copper, which is then collected from the bottom of the pile.
Those opposed to the mine are concerned about the fate of the acid-laced ore once the operation closes.
Western Copper is proposing rinsing the heaps with water and an alkali treatment to neutralize the acid.
However, some experts doubt whether the ore will ever be adequately neutralized and there are fears heavy metals from the site will drain into the surrounding watershed.
The minesite is nine kilometers from the Yukon River and it would be disastrous for salmon and other wildlife if copper leached into the water system.
“We’ve spent a lot of time on this assessment,” said executive committee member Stephen Mills.
“Closure and reclamation issues had to be reviewed in great detail; we had to be sure that the detoxification plan would prevent any toxic effluent from leaking into the Yukon River system.
“Numerous potentially significant adverse effects were identified during the screening and the terms and conditions recommended within the final screening report will mitigate or eliminate those effects.”
The report recommends 26 mitigation measures to deal with concerns, such as insufficient closure of the mine and post-closure runoff.
Western Copper will be required to treat its first cell of the heap as a field-scale trial of the heap-leach process and report the results to regulators.
And to minimize the likelihood of an insufficient closure, security deposits will be held.
The amount of this deposit will be reviewed and revised on an annual basis and will be calculated based on the estimated 10 years it will take to detoxify the heap.
Western Copper had originally told the assessment board a clean-up would only take four and a half years.
However, independent consultants hired by both the Yukon government and the assessment board found that it would take twice as long.
The Yukon government now has 45 days to issue its decision document based on the assessment board’s recommendations.
If approved, the mine could be up and running in as little as two weeks, according to the company’s website.