Monday, October 26, 2015

Construction Waste or Resource?

How we build is a both a sign of our affluence and effluence.  Spending on U.S. construction projects rose in August to the highest point in more than seven years, fueled by home building and government projects. It rose to a seasonally adjusted annual rate of $1.09 trillion, the highest level since May 2008. 

Construction has a significant impact on the environment, accounting for one of sixth of the world’s freshwater withdrawal, one-quarter of its wood harvest, and two-fifths of its materials and energy flow. These structures also impact areas beyond their immediate location, affecting watersheds, air quality and transportation patterns of communities.[2] Green Building is being embraced by the construction industry because of simple economic and environmental reasons. Also more sustainable building practices are evolving more effective design and operations because of competition and new performance requirements.

An estimated 136 million metric tons of building construction and demolition (C&D) waste was generated in 1996.  This equates to an estimated 2.8 pounds per person per day.   Forty-three percent of this waste is generated from residential sources and 57 percent from non-residential sources.   Building demolition accounts for 44 percent of the waste stream and renovation generate 44 percent and 8 percent was generated on construction sites[3]. Road and bridge debris, land clearing debris and other sources are not included in this estimate. 

According to the US Green Building Council there is as much C&D produced as municipal garbage. Buildings consume 40 percent of the raw stone, gravel and sand used globally each year. This material can be deconstructed into: rock, soil, concrete, asphalt, brick, block, woody debris, metals and other valuable recyclables during the demolition process. Also this scrap can range in size from dust or fines to huge concrete slabs. 

The largest portion of C&D by weight recovered is asphalt. Since it comprises 92 percent of our nation’s highways and roads, recycling asphalt occurs constantly since all you have to do is take it back to the plant, reheat it, and mix it with a new batch of asphalt. Certain adjustments are made so to make the chemistry of the recycled asphalt softer. This recycling is driven by bottom-line reasons--to cut road costs and meet limitations of landfilling this materials as hazardous waste. Byron Lord, deputy director of the Office of Pavement Technology states, “ For every ton of municipal solid waste, our nation generates 35 tons of non-hazardous industrial waste.”[4]

Transportation costs drive another major C&D recycled product, concrete. According to a United States Geological Survey study, “Crushed Cement Concrete Substitution for Construction Aggregates- A Materials Flow Analysis,” author Thomas Kelly sees advantages in recycling cement/concrete since its proximity and availability like a mine site located on a construction site (

Waste wood such as 2x4s, plywood and other dimensional lumber, old pallets, stumps and other debris can be transformed by tub and other type grinders that grind this woody debris into landscape mulch and wood chips for either ground cover or as fuel.

There are many other economically viable reasons that C&D should be recovered and not wasted. Metal related components are another small but significant recyclable in C&D waste. Depending on the site and local markets for metals, ferrous and non ferrous recovery of interior frames, shelves, wiring, pipes and electrical fixtures may be prevalent depending on the type of building newly constructed, renovated or torn down. Finally, old corrugated cardboard (OCC) is just another by-product that can be recycled back into new OCC.

C&D may contain hazardous materials depending on what type of structure was built or excavated. Adhesives, asbestos, lead-based and other types of paints, roofing cement, oils, lubricants, brake fluids, mercury lamps, PCB light ballast, formaldehyde in carpets, treated woods, oil-contaminated soils, and a variety of other toxins must be screened out.

C&D landfills may not have linear requirements similar to Subtitle D MSWL’s or muncipal ones.  C&D storage requirements may require contaminated debris be placed on impermeable material bermed to prevent ground and surface water contamination. Some states in this country do not have corrective action requirements, or require groundwater monitoring requirements, or comprehensive financial assurance requirements for closing these C&D landfills.

The Green Building Council is promoting a voluntary rating called Leadership in Energy and Environmental Design (LEED) that all building enterprises and construction firms must comply with to become certified. For example credits are earned for accommodation of at least a 75% recycling rate. 

Other opportunities also exist such as renovating old buildings by saving the masonry, concrete, steel, and wood building shell by modernizing the interior systems. Also selective demolition can conserve existing installations by exercising care in the design process--not only reducing the costs of waste removal but saving on the existing installation costs through repair. Many demolished structures offer such reusable materials as doors, windows, and wood framing materials, and beam, girders and other structural elements, as well as finishes and trims, fixtures and miscellaneous ornamentation.

Finally, construction waste may be prevalent when materials are cheaper to toss compared to the labor costs. In such a busy work setting the haste to finish the job may result in more waste. However, numerous cities in the US are becoming more active in C&D recovery because transportation costs and disposal fees tend to be higher. Active waste screening at C&D landfills is essential in protecting public health in the future. There is enormous recycling of C&D in the US, but still an enormous amount of C&D that needs to be recycled. Any new building or demolition project now can implement better planning, design, recycled product purchasing and frugal resources management as a way to improve business performance.

[1] National Science and Technology Council, Sunbcommittee on Construction and Buildings, Prelimnary Report (Washtington DC 1993)
[2] David Rodman and Nicholas Lenssen,” Builidng Revolution:  How Ecology and Health Concerns Are Transforming Construction,” Worldwatch Paper 124 ( Washington, D.C. March 1996)
[3] Franklin Associates, “Characterization of Building-Related Construction and Demolition Debris in the US,” USEPA, MSW, OSW, June 1998, pg ES-4.
[4] Brian Taylor,” The Daily Grind and Crush,”  Recycling Today,  July 2000, pg s48
[5] ICF Inc.,  “C&D Waste Landfills,”  USEPA/OSW, Draft report 2/95, pg. Es-1