Recyclers of construction & demolition (C&D) materials are no strangers to C&D fines. While these byproducts of the C&D screening process account for a significant volume of what recyclers produce, the challenge of finding a home persists.
According to a 2017 survey conducted by the Construction & Demolition Recycling Association (CDRA), the total volume of C&D mass-generated in the U.S. in 2014 was 583 million tons, of which 73 percent was recycled. Conversely, in that same year, 15.1 million tons of C&D fines were generated, with only 44 percent being recycled.
The issue at hand is fear of contamination. Although some recyclers have been able to find homes for their fines as landfill cover for odor control, fill material for shaping and grading projects and as an agricultural amendment, concerns over concentrations of contaminants such as lead, arsenic, polycyclic aromatic hydrocarbons (PAH) and sulfate have impeded fines from being more readily accepted by would-be customers.
Making the issue more complicated is that what might be acceptable contamination thresholds in one state may differ entirely from the next. Pressure from regulators and environmental agencies to stay under these thresholds can hinder recyclers’ ability to successfully repurpose these materials, resulting in the need to pay to dispose of them in the landfill as waste.
However, despite some of the challenges of marketing fines, recyclers have the power to help reframe the narrative. According to a 2018 study titled “Guidance for Beneficially Reusing Construction & Demolition Debris Fines” conducted on behalf of the CDRA by Timothy Townsend, a professor of environmental engineering at the University of Florida, recyclers inability to market fines stems from a wide variance of products. He says that by controlling the materials entering the waste stream, such as by pulling out drywall or wood, recyclers can help mitigate some contamination concerns. He adds that proactively separating, washing and applying treatment applications to materials can also help improve fine concentrations.
By focusing on improving the stream coming into one’s facility, Townsend says recyclers can collectively cast fines in better light for regulatory bodies and commercial customers alike.
“Materials being proposed for beneficial reuse are often compared to the most conservative risk-based thresholds to determine if a material has the potential to harm humans or the surrounding environment,” Townsend’s report states. “If chemical concentrations are above certain risk thresholds, C&D facility operators can limit the risk of exposure by mixing C&D fines with clean soil, placing clean soil over the material, or using products in less populated areas.”
Although the need to treat fines is dependent on individual recyclers, the collective industry needs to come together to help ensure the products it produces are reflective of good faith operators interested in promoting safe, stable products.
Read “Pioneering a solution for C&D fines” on p. 50 to learn how one Pennsylvania-based recycler has worked to create a use for its fines as fill material in a non-active coal mine quarry.