BioCycle September 2009, Vol. 50, No. 9, p. 24
Findings from a recent U.S. EPA report indicate that large quantities of C&D materials are available for reuse and recycling.
THE U.S. Environmental Protection Agency (EPA) is making reuse and recovery of construction and demolition (C&D) materials a priority as a means to conserve landfill space, reduce the environmental impact of producing new materials (including greenhouse gas emissions), create jobs, and reduce overall building project expenses. EPA’s initiatives include promoting recovery of materials through outreach and education, recognition of successful recovery efforts and participation in green building and green highway programs.
To measure the progress of these recovery initiatives as well as design effective programs, EPA needs to be able to quantify the amount of C&D materials generated and recovered. As part of its measurement efforts, EPA recently issued a document entitled: Estimating 2003 Building-Related Construction and Demolition Materials Amounts (EPA530-R-09-002, March 2009; www.epa.gov/cdmaterials). This document seeks to determine the amount of building-related C&D materials generated and recovered in the U.S. during 2003, updating the findings of the 1998 EPA report Characterization of Building-Related Construction and Demolition Debris in the United States (EPA 530-R-98-010). The methodology used to estimate the amount of building-related C&D materials generated and recovered in the U.S. during 2003 was based on national statistical data and typical waste generation during building construction, renovation, demolition, or maintenance activities. The 2003 recovery estimate relies on data reported by state environmental agencies.
There are four stages in the C&D materials management process: 1) Generation at a job site; 2) Transport to the processor/user of recycled materials/landfill (if not used on site); 3) Processing/incinerating/disposing of the material; and 4) Using the recycled materials. Estimating the amount of materials used in any stage can be done by conducting surveys of the organizations involved during each stage. This can be challenging, depending on the sample size and the response rate, thus few entities collect this kind of information. EPA used limited data available to calculate the generation and recovery estimates.
ESTIMATING THE GENERATED AMOUNT
Methodology used in the new report focused on estimating the generation and recovery amounts from buildings only, not from other structures such as roads, bridges, water treatment plants and power generation plants due to a lack of data. The methodology used national statistical data and typical waste generation data from construction, renovation, and demolition sites. Land clearing materials were excluded from the C&D estimates in this report because the site materials composition studies used to estimate the amount of materials generated at a typical job site did not include land clearing.
Table 1 presents the results of this methodology; building-related C&D materials is broken down by source type (i.e. residential construction, nonresidential demolition, etc.). Figure 1 presents the contribution of each source of C&D materials to the total waste stream. The total amount of C&D materials generated in 2003 was estimated to be 170 million tons, a 25 percent increase in generation from the 1996 estimate of 136 million tons. During the same time period, total construction spending increased 50 percent; however, it was estimated that building construction increased only 32 percent, according to the U.S. Census Bureau. Construction spending increases can also reflect inflation, profit and other factors that do not necessarily correlate to increased materials use.
EPA is aware that, by only focusing on buildings, this estimate may miss a large amount of the C&D materials generated. For example, concrete is one of the most commonly used materials in construction; Portland cement is a key ingredient in concrete. As shown in Figure 2, the Portland Cement Association estimated that buildings consumed only 47 percent of cement produced in 2003.
Recovery of building-related C&D materials for recycling, beneficial use, reuse or waste-to-energy in 2003 was estimated using data reported by state environmental agencies. EPA looked at a variety of data sources regarding C&D materials management and found that state environmental agencies were the most reliable source. However, few states report the amount of C&D materials recovered, disposed and/or generated. Additionally, states vary in their definitions of “C&D materials,” “recycling,” “generation,” “disposal” and related terms, thereby adding further variability to data reported. Methods for gathering the data vary among the states as well. Thus comparisons of state reported numbers must be viewed with caution.
Table 2 lists reported disposed and recovery amounts. Approximately 48 percent was estimated to be recovered, based on state-reported disposal and recovery data. This recovery estimate is a 23 percent increase from the 1996 estimate. Comparison of these estimates should be viewed with caution because data limitations created the need for different methodologies in 1996 and 2003.
TREND TOWARD RECOVERY
While accurate measurements of C&D generation and recovery are critical to strategically increase C&D materials recovery, quantification is hampered by a general lack of data. C&D materials estimates presented to date by various entities, including those estimates here, have some level of uncertainty, and the results should be viewed in that light. EPA believes that these estimates for 2003 reflect and are based on the best data currently available.
Data uncertainties aside, it is evident that large quantities of recoverable and useful C&D materials are available in the U.S. Interest in green building techniques and, in some areas, the decrease of available landfill space, have had a positive impact on the rates of recovery of C&D materials; until recently, the rise in commodity prices had a similar impact. EPA will continue to work in partnership with state environmental agencies, the Associated General Contractors of America, the Building Materials Reuse Association, the Construction Materials Reuse Association, the National Association of Home Builders, the National Demolition Association, and other stakeholders to actively promote recovery of C&D materials.
Kimberly Cochran, PhD, is an Environmental Engineer with U.S. EPA Office of Resource Conservation and Recovery.
September 16, 2009 | General
C&D Generation And Recovery In The U.S.
BioCycle September 2009, Vol. 50, No. 9, p. 24