Cleanup of historical mines in Nova Scotia to begin next year

Decades after they were abandoned, some historical mines across Nova Scotia are set to be cleaned up starting next year.

Gold, coal, gypsum and limestone are among the rocks and minerals that were mined in the 19th and 20th centuries before there were environmental regulations. Toxic tailings were left behind, and continue to stand in the way of natural regeneration of the land.

"You do see it creeping in, but it would probably take a couple hundred years for Mother Nature to regrow and re-establish herself on the sites," said Donnie Burke.

Burke is a senior environmental director with Build Nova Scotia, the provincial Crown corporation that's been tasked with remediating 60 abandoned mines.

In an interview, he said he expects cleanup at the first three sites to start in 2025.

Those three are the Montague gold mine in Dartmouth, the Goldenville gold mine on the Eastern Shore, and a site next to Lake Enon in Cape Breton that was mined for celestite, and later used to process lead, barite and magnetite.

Burke said those three sites were prioritized based on an analysis of dozens of parameters including the location, who owns the land, and perhaps most importantly, the risk the contamination poses to humans and the environment. 

Each of the 60 sites were categorized as either low, medium or high risk.

Montague and Goldenville are both considered high risk. The mine at Lake Enon is considered medium risk.

'They're blights'

In many cases, contamination from historical mining has left the earth barren.

"They're blights," said Burke. "To get vegetation growing back on that and have those carbon dioxide sinks and have these areas remediated — it's the right thing to do," he added.

Linda Campbell, a professor of environmental science at Saint Mary's University in Halifax, said in the case of gold mines, toxic tailings containing arsenic and mercury were directly deposited in low-lying sites near freshwater.

Now those tailings are moving downstream to other water bodies and the ocean, and contaminants are being blown to other areas as windborne dust, Campbell explained via email.

She and her research team have been studying the effects of mine tailings on aquatic systems in historical gold districts around Nova Scotia for a decade.

Will cost $148M, at least

The province's latest cost estimate for cleaning up all 60 historical mine sites is $148 million, and that figure will almost certainly grow.

A dozen of the sites have been costed in detail:

• Montague - $30.2 million.
• Goldenville - $34.3 million.
• Lake Enon - $1.6 million.
• Goldbrook Lake and Seal Harbour (two sites combined) - $8.8 million.
• Ocean Street - $468,804.
• Mooseland - $15 million.
• Widow Point - $250,000.
• Miller Lake-Fleet Settlement - $1.1 million.
• Mill Village - $425,750.
• Lochaber - $250,000.
• Country Harbour - $5 million.

The rest have a generic figure attached while they await a complete assessment. High-risk sites have $5 million, medium-risk sites have $500,000 and low-risk sites have $250,000.

In all cases, the figures are still only estimates. No contracts have been signed with companies that will do the actual remediation work.

'It is time'

Campbell said it's worth the price. She noted that chemicals in old tailings are dangerous for both humans and animals. Arsenic is associated with some types of cancer and metabolic diseases, while mercury is neurotoxic.

"The human and environmental health risks from those highly contaminated historical gold mine tailings are elevated in many areas. It is time for us to resolve this 150-year-old issue," she said.

Burke said the Montague mine is the closest to the start line.

"We're making sure we do this right the first time so that it becomes the model for the other 60 sites that we may put through the process," he said.

So far, Burke said the project does not trigger the requirement for a provincial environmental assessment, but he expects there will still be some public and Indigenous consultation before work can begin.

He estimated there's about 15 years worth of work ahead to remediate all the former mines.