Recycling

Construction crew recycling carpet padding

In Minnesota, turning the 1.6 million tons of construction and demolition (C&D) waste into a valuable resource depends on the availability of markets. Some materials such as cardboard, metals, and plastics have established recycling markets. However other materials, such as sheetrock, do not. This poses a challenge and opportunity for C&D recycling.

Common C&D waste

Aggregate represents 15 percent of the waste stream. It includes concrete, asphalt, and brick materials. Aggregate is often crushed on-site or sent to a C&D Material Recovery Facilities for processing. This material is used in roadways, foundations, and parking structures.

Carpet and padding represents four percent of the C&D waste stream. It's also found in mixed municipal waste. To avoid contamination with other material, it's best collect and separate on-site during construction and renovation. At this time, opportunity to economically recycle carpet only exists in close proximity to the Twin Cities area.

Metals make up three percent of the C&D waste stream and consists mainly of aluminum, copper (non-ferrous) and steel (ferrous). If large enough volumes are generated on-site, metal recyclers will sometimes offer containers at a low or no cost cover transportation cost.

Paper, mostly comprised of corrugated cardboard, accounts for three percent of the waste stream. It is generated during the construction or renovation phase of a structure. Paper is either collected separately or mixed with other materials for separation at a C&D Material Recovery Facility and has well-established markets in Minnesota. Other paper materials are excellent candidates for mixed biomass fuel.

Plastic makes up approximately four percent of the C&D waste stream. It consists of PVC pipe, packaging, film, vinyl siding, HDPE buckets, and other plastic material. Plastics are predominately generated during construction, renovation, and demolition. As with all materials, the less contamination they are exposed to the better their marketability. Plastic would be better collected separately at the job site. Plastics that are contaminated or have no market are good candidates for mixed biomass fuel.

Roofing shingles are predominately found in residential projects and represents 15 percent of the C&D waste stream.  The primary economic driver for “tear-off scrap shingle” (TOSS) recycling is the virgin asphalt cost (i.e. asphalt binder oil) savings derived by hot mix asphalt producers. Minnesota Department of Transportation specification 2360 allows TOSS as an asphalt binder in plant mixed asphalt mixtures to a maximum of five percent of the total weight of mixture.

Wallboard, often referred to as sheetrock or drywall, account for about 12 percent of the C&D waste stream.  Currently, Minnesota does not have an economically viable market for wallboard.

Wood material can be recycled for a variety of uses. At 23 percent, it makes up the largest portion of C&D waste. There are two broad categories of wood:

  • Clean:  Includes tree waste and “non-treated wood” consisting of dimensional lumber and pallets.  Clean wood is used for animal bedding, landscaping material, and clean biomass fuel. 
  • Mixed: Includes manufactured wood products such as plywood, painted wood, particle board and furniture. Treated or manufactured wood can be used for mixed biomass fuel provided the solid fuel boilers meet the permitting requirements and air pollution control equipment.

Processing materials

Whether it’s a construction or a demolition project, there are several factors to consider before deciding on how to process the waste material, they include:

  • Size and location of project
  • Material type and volume
  • Market for waste material
  • Timeline

Depending on your project, there are two ways to process waste material.

On-site source separation

Some materials command better market prices if they are free of contamination. If sufficient volumes exist, it may be economical to hire a contractor or rent processing equipment (crusher, grinder, shredder). This type of processing can help to reduce transportation costs and enhance profitability by hauling the separated material directly to market. In some cases, the material is simply hauled to permitted disposal facilities and stockpiled until volumes warrant processing and marketing.

Mixed material collection

Other circumstances may prevent source separation, but rely on C&D material recovery facilities. These facilities can sort and process mixed materials such as metals, concrete, cardboard, carpet, asphalt, shingles, ceiling tile, vinyl and aluminum siding and wood. Unlike source separation at the job site, a higher frequency of contamination exists at these facilities. However they commonly recover 50 to 75 percent of all materials, by weight. Here's a list of C & D material recovery facilities in Minnesota: