Study Delivers “One-Two Punch” on Stormwater Runoff from Copper Roofs
By Joe Gorsuch, Copper Development Association (CDA), Manager, Health, Environment and Sustainable Development
A Towson University study that uses planter boxes and swales to reduce the adverse effects of copper in stormwater has provided a successful “one-two punch” in reducing the concentrations of the metal in roof runoff.
The CDA and the International Copper Association, are supporting a study that was launched in 2012 by scientists at Towson University, near Baltimore. The study is designed to determine how best management practices could reduce copper in roof runoff to aquatic and terrestrial organisms. The researchers built a copper-roofed picnic shelter with control measures to assess the amount, biological availability (bioavailability) and treatability (removal of copper) of stormwater runoff generated by the structure.
The researchers have found that the planters and swales (through which roof runoff is diverted) significantly reduce the amount of copper – some 83-99% — after collecting data on 19 storms. In addition, the bioretention and biofiltration systems alter the chemistry of the runoff as it passes through. Model calculations made using stormwater data indicate that the change in runoff chemistry makes copper less bioavailable. It also shows that treated runoff is less likely to cause terrestrial or aquatic toxicity. The study, now 90% complete, will be finalized by 2015.
The CDA and project team members are encouraged by these findings. We’re getting the word out to a variety of audiences, including the American Public Works Association, the SETAC (Society of Environmental Toxicology and Chemistry) and meetings of the Roofing Industry Committee on Weather Issues (RICOWI). This study is just one more example of the safe and sustainable use of copper.