The Montague Gold Mine on the outskirts of Dartmouth, N.S., is full of toxic waste from historical mining that ended in the 1940s.

The mine produced more than two tonnes of gold in its day, but high levels of mercury and arsenic were the result.

With growing environmental concern, Build Nova Scotia promised to start to clean up 60 historical mine sites next year, which will cost at least $148 million. 

But one researcher says the best approach to remediation might be to leave some wetland tailings…