Can turning waste into aggregate save agricultural land from turning into gravel pits? IG News

IG News Updates,

If approved, Wilmot Township could soon have a new gravel pit, which will be built on approximately 57 hectares of agricultural land. Despite protests from local activistsBut a Guelph, Ont., researcher says that turning waste into aggregate could provide an alternative to what farmland might lose in the future.

Rafael Santos, an environmental engineering professor at the University of Guelph, is researching how to use recycled concrete, mining waste or residues from steel making as a composite alternative.

He says it’s not perfect – but it has potential.

“There are still a lot of uncertainties,” Santos said. “Whenever you try to replace a natural material that has been optimized for a certain application over many years, you now come up with something that is similar but not exactly the same, it produces [some] Challenges.”

He said they are still working on how much recycled material can be used, the recipe of the mix and how long it will last once applied.

Portrait of Rafael Santos in blue shirt.
Rafael Santos is an environmental engineering professor at the University of Guelph, and conducts research into using recycled materials as a composite. (Submitted by Rafael Santos)

According to the Interactive Pit and Mine Map of the Province of Ontario, there are a total of more than 80 pits in the Waterloo region which equates to approximately 3,122 hectares of land. That’s more than 5,900 football fields, but only 0.7 percent of prime agricultural land in Ontario has a total license.

Most of the potholes in the Waterloo region are in North Dumfries – there are more than 40 in the township. There are also potholes in Kitchener, Wellesley, Wilmot, and Wuwich.

Current use of recycled aggregate

Products such as recycled brick and concrete are currently being used for aggregate, but Santos said the applications are limited.

“Basically what is happening is that with less fixed materials, you will find less resistance to using them for non-structural applications than for structural applications,” he said, citing examples such as sidewalks versus apartment complexes. Where did you go?

Waterloo Region has rules for how recycled aggregate can be used. It can only be used for road base or sub base and asphalt base, which will be under the road or asphalt surface.

Santos explained that the engineering of new forms of aggregates is still improving, and he expects that as it does the regulations will change to allow its use in more applications.

“It’s an inherent issue with construction,” he said. “We’re always building a bigger safety margin because of the types of applications these materials have, you know, bridges and tunnels and skyscrapers and so the safety margin is kept quite large.”

“I think as more pressure builds on when old infrastructure needs to be decommissioned and recycled, I think they will put pressure on finding more uses for it. As we better understand the durability of materials and other factors, things will move even further.”

A man is standing in the field.
Reser believes that resettlement can help save agricultural land if the laws are followed. (James Charney/CBC)

other options?

Mark Reiser, vice-president of the Ontario Federation of Agriculture, says another option for turning prime farmland into aggregate pits would be to obtain gravel from elsewhere.

“Wherever in all of Ontario there’s a limestone bedrock for goodness sake, or glaciers on top of it,” Reiser told the CBC.

“Is it more expensive perhaps to bring it a longer distance to where it’s needed? It could be, but the only reason it’s here in Ontario in the first place is because of a glaciation predicted 10,000 years ago.”

Sharon Armstrong, vice-president of the Ontario Stone, Sand and Gravel Association, doesn’t think moving long distances is the answer.

“We need a balance because the aggregate – to be environmentally responsible – has to be closer to the market,” she said. “So that means some of those sites are going to be on agricultural land and we need to be able to get the aggregate out, closer to the market to reduce truck traffic, but then turn that land into something productive.” Put it back in agriculture when we’re done.”

Sharon Armstrong stands in front of a toy dump truck filled with rocks.  There's a sign on the truck that says, "I'm building a highway."
Sharon Armstrong is the Vice President of Communications and Operations for the Ontario Stone, Sand and Gravel Association. She said that over time most of the composite potholes would be rehabilitated. (Submitted by Sharon Armstrong)


The Ontario Aggregate Resources Act mandates aggregate pits to undergo “progressive rehabilitation” as companies extract raw materials. This means that farm land needs to be moved back to the farm, and companies must do so as they go along versus waiting until all of the aggregate has been extracted.

Racer says it’s a good plan – if it’s followed.

“All the time I’ve spent visiting sites has been spent on visits by [Ontario Stone, Sand and Gravel Association] … I have never seen a site that has been brought back to its original productive potential. They don’t do that,” Reiser said.

“This is farm land. You take out the gravel, you restore it back into the field. It’s not being done. It’s never been done. I question whether anyone can do it.”

There is no time frame for when the licensee must rehabilitate the land, which Reser said he wants to see.

“For goodness sake, farmland is a non-renewable natural resource,” Reiser said. “It is a perpetual resource that if you treat it well it can continue to produce food forever. The aggregate resource is a one-time deal. Take it out, it’s gone forever.”

Portrait of Sue Foxton, North Dumfries Mayor.
Sue Foxton is the mayor of North Dumfries, the third largest aggregate producer in the province. (Kate Beuchert/CBC)

Sue Foxton, the mayor of North Dumfries, said her township is the third largest total producer in the province. He has also seen some total pits being converted back to farmland.

“Some of them are quite good at rehab and do amazing things,” he. “But it is not ideal.”

But Armstrong says gravel pit rehabilitation is the norm.

“I would say it’s 100 percent or close to 100 percent of the total sites licensed over the past 30 years will eventually be rehabilitated,” she said.

“It’s really important that all the content is removed because otherwise you’ll have more sites,” she continued. “So it’s really important that the sites stay open until all that content is gone, so that’s the reason why the sites stay open.”


Most Popular