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Recycle Construction and Demolition (C&D) Debris
Construction Waste Handbook
Worksheet Economics
C&D Resources
Education Program
Overview
Construction and demolition (C&D) waste accounts for an enormous amount of the waste stream in the United States. While most of this waste accrues to landfills, estimates are that 90 percent of the waste stream is potentially reusable or recyclable. There are two main approaches and a third emerging practice for systematically addressing the C&D debris cycle.
- Central Processing Facility: Transporting of mixed C&D waste to a central processing facility where high graded material is sorted from the debris. The mixing of the reusable materials with other debris such as nails, paint, oil or plastic can limit their potential to be recycled due to contamination.
- Job Site Material Recovery: Separation of selected materials at the job site followed by transporting the materials directly to the markets for those materials. This approach can result in a larger amount of material recovered but is a less common practice due to factors such as lack of experience with this method, lack of on site space and the timeline set for building completion.
- On-site Material Processing: This emerging method consists of processing selected materials for end of life use at the job site. It takes tactics from the two main approaches and deploys the technology to the site through on-site grinding using a portable residential scale grinder. This technique is inspired by the biological notion that waste equals food. The concept of waste equals food is exhibited by nature every day and human emulation of such concept can enhance natures abilities.
Cities and agencies throughout the United States have successfully employed numerous waste mitigation strategies for C&D waste. Contractor strategies, building code specifications, and a practice called "optimum value engineering" can all help to minimize the C&D waste stream. Methods such as deconstruction rather than demolition, "efficient framing" and city adoptions of reduction goals have also shown to greatly reduce the C&D waste stream. Most important perhaps is the policy prospective of the political jurisdiction that operates the landfills.
Reuse and Recycling Options for C&D Debris
There are many options and applications of the recyclable material generated by building sites. These include use as an industrial fuel source, mulch in composting operations, animal bedding, soil amendment and reuse as building materials. Material such as gypsum board (which many landfills are prohibiting from entering) can be ground up and used in many different ways such as in the making of Portland cement or as recycled content for new drywall. There are also many resale stores in the H-GAC area that accept building materials and salvaged parts for resale to the public. Also a nonprofit organization Historic Houston does the ultimate recycling by accepting a limited number annually of whole houses for redeployment.
C&D Debris Regulations
C&D waste is mainly regulated on a state-by-state basis with requirements and facilities varying widely. Because of growing awareness that C&D debris can contain hazardous materials, some states are in the process of revising their C&D debris regulations to minimize or eliminate the amount entering their landfills. Policies are also being implemented throughout the nation to encourage C&D recycling. A growing threat to C&D debris recycling is the increase in franchise agreements between demolition contractors and municipalities around the country. These agreements result in a decreased flow of C&D waste and other debris to waste recyclers. There are many best practices steps that local and state governments can take to encourage C&D debris recycling including (but not limited to) implementing policy, providing tax incentives, rebates, sales tax exemptions and low interest loans to recycling businesses.
Specifics for Texas
C&D waste comprises about 22% of the total Municipal Solid Waste (MSW) stream in the state of Texas and 38% of the total waste stream in the thirteen county H-GAC region. There is an abundance of land dedicated to solid waste disposal and so, if compared to the rest of the nation, it remains very inexpensive to own and operate a MSW facility in Texas. Texas has regulations for licensed landfills and effectively monitors them to the fullest of their capabilities. Left for municipalities to deal with is a large amount of non-licensed dumpsites.
The Houston Advanced Research Center (HARC) hosted a roundtable May 26, 2005 to discuss both the perceived barriers and disincentives to the implementation of C&D waste recycling programs and public outreach materials. In attendance were representatives from varied organizations, contractors, builders, engineers, the recycle and salvage industry, landfill industry, remodelers, architects and the community. Such barriers that arose were as follows: an abundance of inexpensive land, tradition, price and cost confusion, uneducated trades and builders, lack of communication with political representatives, big powerful lobbies, few positive public and private models and a lexicon of confusion.
C&D Waste Stream Audit
The Houston Advanced Research Center contracted with the Houston-Galveston Area Council (H-GAC) to conduct a residential waste study by performing waste stream audits of two sites. Working the Tom Cox Builders, Inc., HARC audited the waste stream of two large custom house projects and applied an on-site material processing technique to the second site. The two houses were of similar size and constructed by the same builder and sub contractors.
The project was documented photographically and a manual logging system was used to identify material and volumes. HARC utilized a calculator frequently cited by the Environment Protection Agency (EPA) which adapted it from a National Association of Home Builders (NAHB) research project to calculate predicted weights of waste container content. Found throughout the study was the varying weight of containers depending on the method used to pack them.
The audit for the first house began in earnest on May 26, 2004 when Browning Ferris Inc., (BFI) delivered the two large 30 cubic yard containers on the site. The plan was two fold, to first estimate the volume and weight of containers and then run the container over the scales full and empty to obtain the actual weights. A total of nine hauls were conducted between July 12, 2004 and January 5, 2005. Of the nine hauls, three consisted of wood material only, one of drywall only and five of commingled material. The total volume of the nine hauls combined was 266 cubic yards and weighed a total of 85,242 pounds.
The second house was approached from the onset with the plan of dramatically reducing the amount of waste going to the landfill. After evaluating different possibilities, the methodology of on-site grinding was chosen due to this house being a large custom home. The volume reduction from bulk waste to ground waste was a little more that a 3 to 1 ratio and the materials were applied as a soil or site improvement material. In house one the builder had to purchase crushed concrete, mulch and fill for the lot while in house two, the reuse of the ground material served this purpose and no extra material had to be bought.
Because on-site grinding can not address every need in the new construction waste stream, a 30 cubic yard container was placed on site to handle the material that could not be ground. A total of three hauls (as opposed to nine) were the result of the non-grindable material. The debris in these hauls consisted of packaging, sheathing, brush, TechShield, mortar and understory clearing. The total volume of the three hauls combined was 90 cubic yards and weighed a total of 13,220 pounds. Clearly the plan to reduce the amount of waste going to the landfill was very successful. The economics of C&D waste disposal in Harris County are such that at the present time using conventional cost benefit analysis it is not economically feasible to believe that on-site grinding is a viable option. Our landfill rates ($ 6.00 cubic yard) would have to basically double for the conventional cost benefit analysis to support on-site grinding.
The research demonstrated that the residential C&D waste stream is substantial for large custom homes. The research also demonstrated a manner in which the residential C&D waste can be diverted from the landfills. The research however was focused on the smallest sector of the smallest segment of the C&D waste stream. This doesn't imply that residential new construction is unimportant, but it does raise some serious questions about what is known about residential renovation and demolition practices, policies, barriers, and market-based potential solutions.
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