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Construction and demolition (C&D) debris represents a significant portion of the total solid waste stream in the U.S. According to 2018 statistics from the U.S. Environmental Protection Agency, the nation generates roughly 600 million tons of C&D waste annually, which is more than double the amount of municipal solid waste that is generated.

With demolition debris accounting for more than 90 percent of the nation’s total C&D debris, the disposal of this material can pose major operating expenses to contractors while also consuming valuable landfill space.

To save on disposal costs associated with C&D debris—and to generate income through the sale of salvaged material—source separation on-site can create high-quality, clean materials streams that can be processed and sold to end markets.

Source separating at construction sites is more common because the nature of construction phases allows for relative ease in separating scrap from waste, but this process can be more difficult during demolition projects.

“The [major] benefit of source separating materials is the higher percentage of material that can be diverted from the C&D landfill entirely,” says James Milburn, managing principal at Chicago-based Milburn Demolition. “This is something we strive for on all [demolition] projects but is oftentimes challenging given the site constraints of any given project.”

Site constraints can pose more significant challenges for interior demolition projects, where limited space and shorter time frames can sometimes make source separating impossible.

“One of the biggest issues we face is space constraints within existing buildings requiring interior demolition,” Milburn says. “For instance, there is often limited space at loading docks, allowing for only one dumpster to be placed at any given time. Sometimes there is no dock space available, and live loading of debris is required. In both cases, separating materials on-site is not an effective option since we do not have enough of each material once separated to provide full loads of various material types.”

Time constraints also are another common issue on interior demolition projects. For contracts with a short time window, the separation and loading of various materials would cause delays in the demolition schedule, which Milburn says isn’t an option unless the owner or general contractor demands on-site separation.

“In all cases, the added costs associated with on-site separation of materials oftentimes prevents us from separating materials. With the majority of projects being competitively bid, we can only perform sorting and separating in a manner that keeps our cost the same or less than commingling of materials,” he says.

Creating a plan

When creating a waste diversion plan that can facilitate source separating, Milburn says several factors can come into play, such as the location of the project, the type of materials being demolished, the price of disposal and the ability for a third-party vendor to sort and divert at an off-site location or sorting facility.

“In Chicago, we are lucky to have a few third-party vendors that make off-site sorting and diverting of materials an easy and cost-effective solution,” Milburn says.

“We always prioritize recycling and diverting of materials, however; cost is almost always the deciding factor. There are some owners that will knowingly pay more for higher recycling percentages, [but] these are few and far between,” he adds.

For contractors to fully prioritize maximizing diversion, Milburn says the financials need to be consistent across the board, which typically occurs when projects are identified with Leadership in Energy and Environmental Design (LEED) goals during the bidding phases.

In other instances, the feasibility of creating a cost-effective source separation plan depends on the end markets for those materials.

“It varies greatly on the geographical location of the work,” Milburn says. “In Chicago, our C&D landfills are allowed to use ADC (alternative daily cover) as a diversion method, making it very easy to divert interior materials, such as drywall and ceiling tiles, as part of the C&D landfill disposal process. In other locations, this is not an allowable diversion, thus making end markets more important to contractors,” Milburn adds.

While major strides have been made in developing recycling markets for ceiling tiles, drywall and carpet, in addition to the traditional paper, wood, metal and plastics, Milburn says they are not yet comparable with the price of traditional bulk removal.

“It will be hard for most contractors to validate time spent on end markets,” he says.

End market opportunities

Although end markets for recovered carpet are in their infancy, Milburn predicts more opportunities could be available in the future.

“The problem right now is there are only a couple types of carpet that [can be recycled] currently, and the other ones are just not economically feasible yet,” he says. “In California, there’s legislation that requires for all carpet to be recycled, but the problem is that everyone separates it, ships it to these people that buy it, or that charge to take it, and to my understanding, a lot of it sits in a warehouse waiting on the process to be affordable.”

However, most demolition contractors will separate a few materials regardless of end markets, including concrete and metals.

“Concrete is always getting separated on-site, and metals are the easy one because there’s value there,” Milburn says. “And then, a lot of times there is some value in separating carpet tiles because those are resalable, and they’re pretty easy in terms of time and money to palletize on-site and ship off by the truckload.

“[We see] the same thing with ceiling tiles. Armstrong Ceilings has a [ceiling tile] recycling program that [contractors] can use, but it’s a little bit tricky to navigate, which is why I think it doesn’t get done very often,” he continues. “It’s not necessarily a cost-benefit to us to participate but more of a net-zero kind of thing.”

Over the next decade, Milburn says he hopes to see end markets for these materials expand to make recycling during demolition projects more feasible.

“Once the market is there, you’re going to have nobody that’s going to push against it. Carpet is the biggest one I’m thinking of. Drywall, on the other hand, is a really tough one because … some states allow it to be used as ADC and some don’t. So, that market for drywall is tough because the people who are fully recycling it [want it] to be clean and not contaminated with any water or anything else.

“I can see in the future there being processes to make that easier. Not a separation processes, but the recycling potential becoming easier for us to accommodate with on-site separation.”

The author is the assistant editor of Construction & Demolition Recycling. She can be reached by email at hrischar@gie.net.