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City, regional staff respond to recent aggregate study

Oshawa director of operations services Mike Saulnier stands in front of 5,000 cubic metres of crushed concrete. The city and Region of Durham have contended a study released by the Toronto and Area Road Builders Association stating the two municipalities are lagging behind in recycling aggregates. (Photo by Dave Flaherty)

By Dave Flaherty/The Oshawa Express

A study that claims the city and region are lagging behind in recycling aggregates has elicited strong reactions from both municipalities.
The study, commissioned by the Toronto and Area Road Builders Association (TARBA), compared the aggregate recycling performance of 20 GTA municipalities.
The City of Oshawa ranked second last, and Durham Region fourth last.
TARBA executive director Rob Bradford told The Express they want to exert some pressure on municipalities to recycle more aggregate materials like concrete and asphalt.
Bradford says Oshawa “simply falls into the category of those who do not allow it.”
“The only reason they got a few points is because they allow a bit of [recycled] materials into their hot mix.”
TARBA also stated that Oshawa was one of the five municipalities that didn’t respond to their survey, but information came from construction industry contacts.
Mike Saulnier, the city’s director of operations services, says the information in the study was “very misleading.”

He says he is personally unaware of exactly who the writers of the survey contacted at the city.

“I don’t know who it went to, or who they called. I’m not really sure what to answer there,” he says.

“We allow recycled materials. We just crushed 5,000 cubic metres of concrete into two piles.”

Saulnier showed The Oshawa Express these materials and said it cost about $100,000 to complete.

Scott Robinson, the city’s chief material inspector, says this shows TARBA is wrong.

“Why would we spend money to make the material, and not use it, it makes no sense,” he questioned.

In the mid-2000s, there was a big push in the industry for municipalities to use recycled aggregates.

“Prior to that, they were kind of waste heaps. Nobody was doing quality assurance or quality control of those piles,” Robinson says.

Initially, recycled materials weren’t high quality. But this is not the case today.

“It’s a great product now, it is quite comparable to a granular A mix we’d use on our roads,” he says. “It’s come a long, long way.”

However, recycled materials have caused issues with developments in the city’s north end.

“We’ve run into calcite issues…basically, the recycled concrete was reacting with the pH in the ground, essentially blocking people’s drain pipes and causing backups,” Robinson explains. “It changed the pH of the water, and once the pH gets too high, the calcite comes out of the solution and turns into a solid.”

Since then, city staff has consistently been told by consultants not to use recycled concrete in such projects.

“When I’m getting told you shouldn’t be using this or you’re going to have all these homeowners with flooded basements, well, I’m not going to use that,” Robinson says. “We are pretty innovative when we use this stuff, do we use as much as other places? Probably not – because we are limited.”

Construction project engineer Mike Harrington points out that while TARBA should be aware of the calcite issue, there aren’t many other municipalities that have been affected, so it may not be common knowledge.

Recycled aggregates are used by the city in a number of other ways. Robinson says examples include unpaved parking lots and road shoulders.

According to Harrington, the percentage of recycled materials the city allows in road resurfacing projects is much higher than provincial standards.

There have been few issues in these cases, except for when the product isn’t clean, Robinson says.

Saulnier points out all materials cannot be reused as some can be “contaminated.”

For example, in a case where there is rebar within the concrete, a recycling operator may be unable to process the material.

“You can damage equipment,” Saulnier points out.

Robinson adds there is a misconception that recycled materials are always a cheaper option.

“It’s a little bit of a fallacy; saying using crushed concrete is going to be a lot cheaper, not necessarily. From what we’ve seen it is the same price if not more,” he says.

Susan Siopis, commissioner of works for Durham Region, says the municipality is “very interested in continuing to work with industry to look at ways of reducing construction waste.”
“We continue to use reclaimed and recycled materials on a case-by-case basis to obtain a better understanding of performance and to improve specifications,” Siopis stated in an e-mailed response.
Siopis says staff believes recycled concrete and asphalt should comply with “stringent specifications” and be used in ‘select’ projects where performance is assured.
However, like Saulnier, Siopis observes using recycled materials does not always equal success.
“We have used recycled product on several projects with mixed results. For example, on a Type A arterial road, crushed concrete granular was used at a reduced price,” she says. “Contamination of the aggregate led to failure of some of the subdrains resulting in failure of the road base with seasonal heaving and settling.”

The region was forced to replace the drains, neglecting any costs savings from using the recycled material.
In another location, recycled concrete was used for road shoulder material and almost instantly presented a problem.
Crushed concrete products have been found to contain wood, brick, plastic or low-strength new concrete or cement mixed in on other occasions.
“These materials are not acceptable in the granular road base of an arterial road.”
In reaction to the region’s ranking, Siopis says the region does not apologize for “being conservative.”
“Long-term performance is essential. It is not environmentally or financially responsible to utilize recycled product if the lifespan of a project will be compromised.”
There are numerous examples of the region utilizing recycled materials successfully.
On major road construction projects, workers process the existing asphalt and granular road base to create a new ‘well-graded road base.’
When asphalt is being resurfaced, the waste goes to operation depots and recycled into material used for grading road shoulders.
“This significantly reduces our operating costs, reduces waste materials and provides us with a road shoulder material which are less susceptible to erosion,” Siopis says.
To her, there are flaws in the entire approach of the TARBA survey.
“The differences between municipalities were not taken into account,” she says.
She points out that four of the 14 survey questions were specific to municipal subdivision roads. Durham Region does not own or operate any of these types of roads.
“There was no ability in the survey to provide an answer of ‘not applicable’. There was no place in the survey to articulate comments such as these. In contrast, the City of Toronto would have a high percentage of local roads in their network. Local roads handle far less traffic and the volumes of heavy vehicles are negligible,” Siopis says.
Durham Region deals specifically with arterial roads, constructed to handle heavy truck and bus traffic.
“It will perform very poorly if the specifications for materials and methods are compromised. Reconstructing a road early in its life cycle does not save money or the environment,” she says.
The director suggests that in the future, TARBA should “allow for more dialogue that provides for fulsome responses and better overall data.”