Diversionary tactics

The construction industry is adopting an increasingly sophisticated approach to waste diversion in order to lighten the load on the province's landfills

By Joseph Caouette

sized-CD-Facility-2 high res

Two points does not always amount to much. It can be a single dunk in a basketball game, or the word "so" in Scrabble. But on a large construction project, two points can represent tonnes of waste saved from the landfill.

There are 110 points up for grabs on the LEED certification checklist, and just two of those points relate to waste diversion: one for diverting 50 per cent of project waste, and another for diverting 75 per cent. Yet, mixed construction and demolition (C&D) waste is usually a serious issue for any city. Current figures are not readily available, but Statistics Canada estimated C&D materials accounted for 25 per cent of the province's municipal solid waste less than a decade ago. As recently as 2012, 20 per cent of the waste sent to Calgary's landfills was still generated by the C&D sector. Diversion may have a modest impact on the scorecard, but its importance to the environment is huge.

So why, in a province rich with recycling options, is there still so much construction waste heading to landfills? In many cases, people simply don't know better.

Nancy Burton, chair of the Alberta chapter of the Canada Green Building Council, discovered this first-hand when she began working in the province. Now based in Calgary, she moved to Edmonton from Vancouver seven or eight years ago. While working on her first local job, she asked to look over the project's recycling receipts.

"I saw all these receipts saying that the drywall had gone to landfill and I was shocked, because in Vancouver you can't send drywall to landfill," she recalls. "The contractor said, 'I don't know what you're talking about—it always goes to landfill.'"

Since then, drywall has been added to Calgary's designated materials list—meaning commercial loads containing the material are charged higher dumping fees—while Edmonton's C&D waste recycling operations keeps the material from cluttering up the Clover Bar landfill. But this lack of knowledge remains one of the biggest challenges to improving waste diversion efforts. In particular, smaller businesses that cannot afford the sustainability departments seen in large companies like PCL and EllisDon may be unaware of many of the recycling alternatives on the market.

"I'm used to working with large contractors and large hauling companies, but there are a lot of smaller guys out there, and they might not even have a website or they may still work from a phone or fax," Burton says. "They don't have the resources to do the research, so they just do what they've done for the last 20 years." 

Looking out for the little guysized-CD-Facility-3 high res

Capturing waste from smaller projects has been one of the primary successes of the University of Calgary's campus-wide C&D waste diversion program, which covers not just large projects like the $158-million expansion of the Schulich School of Engineering, but all construction on campus. According to Adam Stoker, a consultant with the university's sustainability office, capturing the waste generated by these other projects has been one of the great success stories of the initiative.

"It's all the small- and mid-sized projects where historically the construction waste coming out was lost," he says. "It wasn't addressed by our operational waste program, and it wasn't given the same kind of rigour as some of our really big projects."

Over 400 tonnes from projects, ranging from retouching the finishes on a few classrooms to overhauling entire floors, have been diverted from landfills since the school began tracking the information in 2013. To help capture the waste, the university provides a commingled site on campus, which spares contractors the time (and cost) spent sorting materials on site before hauling everything to a landfill.

In Edmonton, these same smaller contractors can take advantage of the city's mixed C&D recycling facility. Before the facility opened in 2012, only 10–15 per cent of Edmonton's C&D waste was being recycled. Now the site is handling waste produced by everyone from independent contractors to construction giants.

"Basically, we're sorting the waste now for the customer," says Renee Rudy, a commercial waste specialist for the city's waste management services division. "Even the do-it-yourself resident can bring their construction waste."

And it seems many are taking advantage of the service. Last year, the facility sorted through 40,729 tonnes of mixed C&D waste containing cardboard, concrete, metal, drywall, ceramics, plastics and wood. On top of that, the city also took in 66,565 tonnes of segregated wood, drywall, asphalt shingles, concrete and metal.

Between both groups—sorted and unsorted—84 per cent of the waste was diverted from landfills. Materials like wood and drywall were used for compost amendment, concrete was crushed into roadway base, and other waste streams were sold to recyclers. Very little finds its way into Edmonton's landfill.

Still, the question remains: what about the 16 per cent that wasn't recycled or reused? These residual materials consist of the small pieces or odd items that simply do not fit into any existing recycling or composting program. Fortunately, the Enerkem biofuels plant will be able to process nearly all of these materials once it is fully commissioned. At that point, the city will be diverting nearly 100 per cent of the C&D waste brought to the site, Rudy says.

Despite receiving nearly 41,000 tonnes of mixed C&D waste last year, the facility did not even use half of its full capacity. It can actually handle 100,000 tonnes annually, or 40 tonnes per hour. Rudy suggests that much of the mixed C&D waste still heading to other landfills in the capital region could easily be handled by the Edmonton recycling facility—if only businesses were aware of the option.

No garbage in, no garbage out

Lessening the burden on landfills, however important that may be, is just one outcome of waste diversion. Any consideration of what is left behind at the end of a project must also take into account what happens at the beginning. In order to prevent waste, project owners need to rethink their design and building practices as well.

To help work toward this goal, the University of Calgary is gathering data on all its construction projects in an online tracking system—DARTT, or the diversion and recycling tracking tool—provided by Waste Management Inc. The school recently crunched the numbers on seven of the large LEED projects completed on campus between 2007 and 2014 to look more closely at the impact of its construction waste diversion efforts.

What the university discovered was a huge gulf between the most successful project (the Child Development Centre) and the least (our sources wouldn't reveal). Compared to the Child Development Centre, the worst offender produced 10 times as much waste per square metre. The university also calculated that the average construction waste produced by one of its buildings was equivalent to over 22 years of operating waste.

As it compares the waste outputs of different projects, the university has already begun to reconsider its approach to future demolitions on campus. The Nickle Arts Museum was almost entirely demolished to make way for the Taylor Family Digital Library, and the DARTT numbers have helped the university better understand the impact of that decision, Stoker notes. The data only adds to the argument to keep an older building around longer rather than reaching for the wrecking ball right away.

There is much more data that needs to be collected before the school can say why one project might produce 10 times the waste as another, but the influence of this information is already being felt on the university's approach to construction. Prefabrication is likely to become an increasingly important tool for improving sustainability efforts, while design choices will need to be considered more closely to ensure less unnecessary waste.

"If you've got a ceiling height of 12 feet instead instead of eight feet, and drywall comes in eight feet lengths, then you're always going to have cut-offs associated with that," Stoker says. "There are things you can do even at that scale to cut down on waste."

That's just one small detail perhaps, but it is also indicative of the increasing sophistication required of efforts to cut down on construction waste. The industry's approach to the challenge of waste diversion has evolved considerably since Burton was explaining to contractors that drywall could indeed be recycled. Like so many others, she now holds the industry to a higher standard, and she expects projects to be earning those two LEED points with relative ease.

"In a lot of cases it just takes a little bit of effort, and it typically falls on the contractor to avoid those one-off pieces of material that they need to avoid sending to landfill," she says. "But the fact that projects are hitting a 95 per cent diversion rate with more regularity tells you that it's not just doable, it's doable in a significant way." 

2015 ACM MMM Button

2015 ACM Email Button


Free account to gain access to ACM digital editions.