Work to clean up contaminated former gold mine site to begin this year

Work to clean up one of the more contaminated former gold mining sites in Nova Scotia is on track to begin later this year, while work at a second site could get underway in 2026.

Donnie Burke, senior director of the environmental group with Build Nova Scotia, told reporters on Wednesday that engagement with the community about the work in Montague Gold Mines, near Dartmouth, is expected within days. The project should then go to tender next month.

"I'm quite confident that you'll see boots on the ground and construction happening in Montague this year," he said.

Burke spoke following an appearance at the legislature's public accounts committee to discuss an auditor general's report on contaminated sites.

Plans for the work were announced in 2018. Burke said it's taken so long to get to this point in part because of the size of the property to be cleaned up.

"Some of these are maybe a city block and some of them are seven city blocks. So it's like anything in construction — the bigger it is, the longer it takes," he said.

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A containment cell about half a hectare in size will be constructed to blend into the natural area, said Burke. It will have capping material to prevent leakage.

The work is expected to take up to three years, followed by long-term monitoring.

Burke noted that the sites in question are frequented by people who hike or use ATVs in the area.

"Some of these tailings have, like, 14 or 16 per cent arsenic in the tailings, so we want to make sure it's contained, confined and managed in a proper way that's environmentally friendly both to human health and ecological health."

A similar approach is being used at a former mine site in Goldenville, near Sherbrooke. The process will take about the same amount of time, said Burke, but is about a year behind the Montague effort due to preliminary work that involved private property.

The site measures between 500 and 600 hectares in overall area impacted over time by the former mine operation, he said.

"So we had to put boots on the ground and look at the whole site because tailings would have been just let go by gravity and carried by stream," he said.

Burke said First Nation consultation is ongoing for a third site, the former celestite mine in Lake Enon, in Cape Breton. When that is complete, the project will move to tender. Because the site is smaller, he said construction should only take about a year.

The province has identified 68 former mine sites to be remediated.

Cost estimates evaluated each year

The most recent update in government financial figures puts the liability for the cleanup of all known contaminated sites in the province at about $600 million, more than half of which is related to the work slated to happen at Boat Harbour.

The figure for abandoned mine sites is about $148 million, with the majority of that — $64.5 million — reserved for Goldenville and Montague. For the remainder, the estimated cost for work at sites rated as high risk is $5 million each, the budget for medium-risk sites is $500,000 and low-risk sites are pegged at $250,000 per cleanup project.

Officials at the committee told MLAs that the figures for cleanup of abandoned mine sites are reviewed and updated yearly. While some might not be remediated, there will be some work required to contain sites.