Giant Mine public forum in Yellowknife on Thursday

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If you have questions about the Giant Mine clean-up operation, there will be a public forum on Thursday evening in Yellowknife.

Head to Northern United Place between 6pm and 9pm to hear leaders of the clean-up project explain what’s been happening at the mine site and what’s next.

Giant Mine, a former gold mine, is one of the most contaminated sites in Canada.

The clean-up plan calls for more than 200,000 tons of arsenic trioxide – a toxic mining byproduct – to be frozen underground.

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Work on that plan began almost a decade ago. The federal government, which is in charge of the project, is inching toward beginning clean-up operations in earnest.

“Arsenic trioxide is toxic and poisonous so it is a big deal. However, we feel we have a really solid plan in place to address it,” said Natalie Plato, deputy director of the government’s Giant Mine remediation project.

“There are 237,000 tons of arsenic trioxide currently stored underground. In addition, there are a lot of contaminated buildings on site that are starting to deteriorate and fall down. There are contaminated soils, tailings ponds, and big pits left over from the mining operations.”

Plato told Moose FM that clean-up workers have now safely taken down and stored a number of highly contaminated buildings, including the mine’s roaster complex, where ore was once roasted to extract gold.

Next, the team will focus on making other buildings safe and ensuring nearby Baker Creek does not encroach on contaminated areas (which, if it happened, could cause contamination of Great Slave Lake).

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The C-shaft headframe is causing concern as engineers report its structure is deteriorating. The headframe may have to be dismantled in the near future.

More details: Giant Mine’s C-shaft at risk

To protect the creek, an empty mine chamber beneath the creek has been filled and the wall of one of the mine’s pits will now be buttressed, to ensure there is no risk of Baker Creek flooding the pit.

In the longer term, options to reroute the creek away from the mine are being examined.

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However, the biggest project will be freezing the many thousands of tons of arsenic trioxide dust and associated waste.

This work has yet to begin and is expected to take more than a decade to complete.

Watch: Giant Mine’s presentation to Yellowknife city councillors (item 3)

“Through the environmental assessment we went through, it was proven that the frozen block – freezing the chambers of arsenic in place – is the best solution,” said Plato. “We’re confident that will keep the environment and the nearby communities safe.

“The arsenic [trioxide] is stored underground in big chambers left over from the mining process, and some that were purposely built to store this.

“It’s like using a skating-rink technology where we put these pipes, called thermosyphons, around these chambers – so it actually freezes it and makes it into a solid block, like a giant ice cube. It can’t move, water can’t get in and it contains it in place.

“That’s the plan for now. It’s the best solution we have.”

Download: Giant Mine’s environmental assessment decision, June 2013 (pdf)

The federal government has committed to reviewing the available science every 20 years, in case new techniques offer a better solution to the problem.

Otherwise, the government has been granted the right to maintain its freezing program for at least a century.

If you want to hear more but cannot make Thursday evening’s forum, there are also drop-in sessions at Javaroma from 9:30-10:30am and 2:30-3:30pm on Friday.

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