It’s water cannons vs. dust at Unimin mine site near Havelock
Mikhail Clarkson points to a 10-acre section of mostly flat, gray hardpan. A scattering of grasses and other vegetation that are taking hold grow thicker close to a pond at one end where a half dozen Canada geese swim.
A series of pipes supply an irrigation system and a few large water cannons.
“Five years ago we maintained this area just like a big desert. It was a beach,” says Clarkson, the assistant plant manager at Unimin Canada’s nepheline syenite mine north-east of Havelock in the heart of cottage country. “There was no grass at all.”
Dust was a real problem, especially on hot, dry windy summer days.
Nepheline syenite is an igneous rock that bubbled up to the surface as lava just over one million years ago. It crushes down to a bright, white powder that is used as a filler in almost all glass and ceramic products and in outdoor paint
The tailings left over after the rock is crushed and powdered had always been “slurried.” That is, mixed with water, pumped out over several flat areas that total about 100 acres and left to dry. Hence the dust.
Water was also a problem. Not technically a problem because the company had permits that allowed it to draw water from lakes on the mine property and discharge effluent back in.
However, like most modern corporations, Unimin no longer frames its environmental obligations as simply meeting the base requirements set by government regulators.
“I think that attitude started to change at about the same time that I was hired on, about 10 years ago,” says Clarkson. That was right after he graduated from Queen’s University with a degree in mining engineering.
“It’s something that’s happening in corporate Canada generally. You use the term ‘social licence to operate.’ You can’t be in industry any more without being conscious of the people around you and the environment in which you work.”
The dust problem came to a head in 2012. After a particularly hot, dry spell, high winds stirred a dust storm that affected cottages and homes on nearby Kasshabog Lake. The company was charged by the provincial environment ministry and eventually fined more than $400,000.
But long before the court case was settled, Unimin had begun a $1.5 million investment that would solve the dust issue, substantially reduce the amount of water the mine uses and completely end all effluent discharge.
One part of the solution was to use water that drains off the hillsides of the property as the mixing agent for slurry. Water is still taken from two lakes on the mine property, Barrette Lake and Big Mountain Lake, but substantially less of it.
A system of filtration ponds now filters the water so it can be re-used in the slurry process. That closed loop means the same water is used again and again. And any remaining water is used to irrigate the slurry fields, which will eventually go back to grass and vegetation.
There was a time when Unimin pumped 1.2 million litres of water out of Big Mountain Lake daily. That number is now down to 450,000 litres. And because rainwater that gathers in the huge open pit mine is pumped back into Barrette Lake in a two-stage process, the net effect there is an addition to the lakes system: on an average day 361,000 litres are pumped out and nearly 900,000 litres of rainwater go back in.
The entire mine site covers 3,000 acres but just 10 per cent of it is actively in use, including the 400-foot deep pit mine, slurry fields, roads and the Nephton and Blue Mountain processing plants.
One section of slurry field is now in the last stage of reclamation.
“We’re doing the final elevation and reclaiming it right now. Were putting down the final layer of grass and sod and we’re going to have a nice hill for the kids to play on,” Clarkson says.
Or maybe another option.
“They’re talking about a golf course. It would make a great golf course.”
This is one of a series of articles commissioned and paid for by Sustainable Peterborough and published in partnership with The Peterborough Examiner. By Jim Hendry, Peterborough Examiner, original article published Saturday, June 18, 2016.