Mark Lennon - Recycling construction and demolition wastes // A Guide for Architects and Contractors: the Periodical of The Boston Society of Architects.

A Guide for Architects and Contractors: the Periodical of The Boston Society of Architects, April 2005 - P. 3-6.

RECYCLING CONSTRUCTION AND DEMOLITION WASTES

Mark Lennon

The Boston Society of Architects

WHY RECYCLE JOB SITE WASTES

The reasons to recycle construction and demolition (C&D) wastes are simple but compelling:
1. Construction and demolition wastes are one of the largest waste streams in the country.
2. Almost all job site wastes are recyclable.
3. It costs less – usually much less – to recycle job site wastes than to throw them away.

One Of The Largest Waste Streams In The Country
Nationwide, it is estimated that as much as 40% of the raw materials consumed in the United States – steel, concrete, glass, and so on – are used in construction. When building stock turns over, all of these materials become waste. This C&D waste stream is enormous: about 130 million tons per year, or about 25% of all of the solid waste that is discarded in the United States.
This waste stream is also very large considered building-by building. The waste that’s generated during construction of a new building is more than the occupants of that building are likely to throw out during one or two years of occupancy.

Almost All Job Site Wastes Are Recyclable
There is hardly a single waste material from a job site that cannot be recycled:
Architectural salvage (doors and door frames, windows and frames, millwork);
Ferrous Metals (structural steel, Steel framing members);
Non-Ferrous Metals (wiring/conduit, plumbing (pipes, fixtures), HVAC (ductwork, motors));
Gypsum Wallboard;
Roofing (shingles, commercial membrane, wood, metal, slate) etc.
In total, from almost any job site, 90% to 95% of all waste materials can be recycled. Appendix A provides additional information on recyclable materials from the C&D waste stream.
There are some materials that aren’t on this list, because markets remain undeveloped or contamination makes them difficult to recycle – for example, fiberglass and foam insulation, painted or papered gypsum wallboard. And some renovation or demolition job sites contain hazardous or special waste materials that need to be managed as such (lead-painted wood or plaster, asbestos floor tiles or siding).

Recycling Costs Less Than Throwing Away
In almost all cases, the cost of recycling is lower than the cost of throwing materials away. Occasionally it’s a near thing – a very small job, a tight site or schedule, an odd mix of materials. However, day in and day out, for the architect, owner, and contractor, recycling makes economic sense...

“SOURCE SEPARATION” OR “COMMINGLED RECYCLING”
As Figure 1 shows, the economic benefits of recycling are highest if waste materials can be separated from each other and recycled individually. This is called “source separation.”
Source separation means separating different recyclable materials at the job site. That is, workers keep metals separate from wood, and wood separate from concrete, and so on, and place each material into a different container. These containers are then transported to different markets.
Commingled recycling is the alternative to source separation. Commingled recycling means placing all recyclable materials into a single container, which is then transported to a processing facility, where different materials are separated by hand or by automated equipment.

Source separation and commingled recycling have distinct advantages and disadvantages.

Recycling Method	Advantages	Disadvantages
Source Separation	• Higher recycling rates • Lower recycling costs; revenues paid for some materials • Often a cleaner, safer work site	• Multiple containers on site • Workers must separate materials for recycling • More complex logistics • Multiple markets; more information to manage
Commingled Recycling	• Only one or two containers on site • No need for workers to separate materials for recycling • Easier logistics • One market; less information to manage	• Lower recycling rates • Higher recycling costs

The biggest tradeoff between source separation and commingled recycling is complexity vs economics.
Source separation is more complex because workers must separate waste materials before they throw them away, there are more containers on site, and there are more markets and haulers to work with and keep track of.
But in most cases, source separation is economically more advantageous than commingled recycling:
• Source separation produces materials that are ready to go directly to market; there is no need to pay a processor to sort materials.
• Source separated materials are generally of higher quality, with fewer contaminants, so they’re worth more in recycling markets.
On balance, source separation is generally preferable to commingled recycling. It costs less, and recycling rates are typically higher.
Complexity is usually not much of an issue. It’s no harder for workers to toss different materials into different containers than to throw them out mixed together. Being smaller, containers for source separated materials can often be placed close to work areas, so that source separation actually takes less time and effort than carrying wastes to a central container for mixed debris.
Nor does source separation imply that every material will be separated all of the time. There will always be a mixed debris container on site, and there will be some materials that are always disposed or recycled as mixed debris. Some materials will also be source-separated during one phase of a job, but handled as mixed debris at other times. For example, in a wood-framed building, wood would generally be source-separated while the structure is framed. But when the project moves on and the only wood waste is an odd pallet or pieces of blocking, these will be handled as mixed debris.
There are some jobs where commingled recycling is the only option possible, because of site limitations, job size, or schedule. In these cases the goal is to identify the commingled processor who can achieve the best combination of price and recycling rate. But where it’s feasible, source separation should be considered the best recycling option.

SOURCE SEPARATION PROCEDURES
The basics of source separation are easy: each recyclable material should be segregated as it is generated, and placed in the appropriate container.

A few additional rules make source separation work smoothly:
Keep as few containers as possible on site at any time. Containers take up space, and having too many containers increases the possibility of confusion and contamination. In general, aim to have one container on site for mixed debris, and one or two additional containers for the specific wastes generated during each phase of the job.
Match containers to the material. A wood container, for example, will typically hold 30 or 40 cubic yards. But scrap metal from wiring and plumbing may need only a 2- or 4-yard container. For something like concrete, you may have a lot of material, but container size may be limited by the weight that can be hauled over the road. Site layout and access also play a role in container selection.
Place containers close to work locations. An advantage of source separation is that it doesn’t rely on one big central container for all wastes. Smaller containers can often be placed close to the work. Also look for opportunities to use intermediate containers like hampers or rolling hoppers that can be placed right next to the work, then wheeled to a larger waste container at the end of the shift. Again, there may be surprising savings in labor and convenience.
What makes source separation work is the fact that it’s matched to the phase of the job. You only have on site the containers needed at a particular time for the specific wastes being generated. You collect, haul, and market these materials. When the job moves on, you recycle different materials, in different containers, and generally to different markets. It takes a little energy and thought to do this, but in most cases the financial savings and the advantage in recycling rates are more than worth it...