Government Issue

Should local and county governments get more involved in C&D recycling efforts.

The economic downturn in America has not gone unnoticed by the government sector. Everyone, including solid waste managers, has felt the economic pinch. Given the task of trying to keep their recycling programs viable with ever-shrinking budgets, many of these managers have had an up-hill battle.

The fact is that, while most communities have programs in place to manage and recycle municipal solid waste (MSW), many are only now beginning to focus on the construction and demolition (C&D) debris stream. However, if efforts are put in place to focus on this untapped area, there could be relief in sight. After all, the C&D debris stream includes materials such as: concrete, asphalt, wood, gypsum drywall and metals generated from the construction, renovation or demolition of roads and structures. As America grows, so does the surplus of these materials, which is why C&D debris management is becoming very important to many communities.

Why does it make sense for recycling managers to focus on the C&D debris stream? Quite simply, the answer is because C&D debris represents a large percentage of the waste stream. According to the Construction Materials Recycling Association (CMRA), Lisle, Ill., the C&D debris stream accounts for between 25 to 45 percent of the overall North American waste stream. The percentage, of course, depends on the region being considered. Areas with heavy population growth are the likeliest to focus on the C&D debris stream because of the development that accompanies population growth.

There may be issues on the solid waste side pushing governments into C&D recycling as well. Due to concerns about ground water contamination, there is mounting interest in requiring C&D debris landfills to be lined. Recent studies have found that C&D debris leachate may not pass primary and secondary drinking water standards.

Some states, such as Florida and Minnesota, are rapidly beginning to consider liner requirements in order to protect ground water sources. To the extent that individual states pass legislation requiring liners for C&D debris landfills, the resulting increased cost of disposal would inevitably provide a boost to C&D recycling efforts.

Composition of C&D debris is another issue. It varies greatly across the country as well because the type of C&D activities and which building materials are being used impacts it. For example, the homes built in central and south Florida are generally built with concrete block frames due to the close proximity to concrete manufacturing plants. Conversely, houses in the northern part of the state are generally built with a wood frame due to their proximity to forests where the wood is harvested. Consequently, the C&D debris in the central and southern parts of Florida contains a large amount of concrete, while in the north there’s a large amount of wood. Thus, recycling efforts must be local and tailored specifically to each region’s characteristics.

There are several different materials generated within the C&D stream, and each presents different opportunities for government recycling coordinators to get involved.

Gypsum drywall typically represents anywhere from five to 15 percent of the C&D debris disposal stream. Until recently, there were very limited attempts – largely focused in the Pacific Northwest – to recycle this material. In recent years, however, drywall disposal and decomposition has caused odor problems at C&D debris landfills. Drywall is already banned from disposal in some parts of Canada. The odor issue has resulted in increased interest in methods and end markets for recycling drywall.

The Florida Department of Environmental Protection (DEP), for example, has recently provided a series of grants to Florida counties interested in drywall recycling. While the grants have resulted in some promising opportunities, the low cost of C&D debris disposal combined with a relatively inexpensive raw material (gypsum) continue to be major barriers to more widespread drywall recycling.

Pressure-treated wood made with chromated copper arsenate (CCA) has caused great concern due to the amount of arsenic in the wood, a known carcinogen. CCA-treated wood is frequently used in construction and ends up in C&D debris landfills as construction, renovation or demolition waste.

In C&D debris landfills, CCA leaches from the wood and mixes with the landfill leachate. Many C&D debris landfills in the country are not lined and, therefore, cannot prevent the leachate from entering the groundwater. Studies performed by the University of Florida in Gainesville, Fla., have shown that leachate from C&D landfills may exceed the primary drinking water standards for arsenic and, thus, may pose a threat to groundwater. Recently, the EPA and the pressure-treated wood industry have decided to phase out CCA-treated wood due to these concerns.

An alternative to disposing of C&D debris in a landfill is grinding the material on the job site. After a small, portable grinder grinds the material (with wood and drywall as two of the largest components), it is placed on the property as a layer on top of the ground before the sod is laid.

Studies are currently being performed in Georgia to test the environmental impacts that this method of disposal may have. A study performed in Indiana found this method to not have detrimental environmental impacts, and current state regulations permit contractors to grind up their untreated wood, cardboard and gypsum drywall from construction projects and place the finished material onsite.

Asphalt shingles are another component of C&D debris. The amount of this material that is recycled, however, is very small. In a recent study performed in Florida, asphalt shingles represented seven percent (283,000 tons) of the total building-related debris stream, while only one percent of that amount (3,000 tons) was recycled.

Asphalt shingles can be recycled into new hot-mix asphalt used in road construction. It can represent five percent of the total weight of asphalt pavement, though some studies have shown that as much as ten percent is possible. The study performed in Florida showed that the market for asphalt is so strong that all of the waste asphalt shingles generated in Florida could be recycled in this manner. (Current information on asphalt shingle recycliing can be found at www.shinglerecycling.com.)

To summarize, as communities continue to feel the budget squeeze, more attention will be placed on those waste streams that represent the largest fractions of total generation. C&D recovery will likely become increasingly attractive to those municipal program managers who are being pressured into maintaining recovery rates while decreasing costs.

Curbside and drop-off programs targeting traditional recyclables may fall out of favor, while streams such as C&D debris pick up steam. Therefore, as a result of this increased interest in C&D debris, technologies and end markets that result in increased efficiencies and higher diversion will continue to be developed. Environmental concerns and increasing difficulty in siting new landfills and/or expanding existing landfills will drive C&D disposal costs higher over time. Government recycling coordinators will need to stay tuned to see how it all develops. Kiim Cochran, Chuck McLendon, Tim Townsend, Ph.D.