First Results Find Evidence that Copper from Roof Runoff can be Controlled
By Joe Gorsuch, Copper Development Association (CDA), Manager, Health, Environment and Sustainable Development
Joe Gorsuch works with environmental regulations and the collection of ecological toxicity data. For 30 years prior to joining the CDA in 2009, he worked with Kodak, conducting environmental effects and stability studies on chemicals in the laboratory and outdoors to register chemicals for the photographic industry. From 2005 to 2009 he was President and Owner of Gorsuch Environmental Managements Services, Inc. [GEMS, Inc.] coordinating environmental studies. Go here for his earlier posts on stormwater and environmental issues.
The amount of copper in stormwater runoff from copper roofs and local waterways has been an environmental concern in some communities. Some state governments are responding to stormwater runoff questions by enacting regulations to monitor for potential contamination. There hasn’t been a definitive study that assesses the amount, biological availability (bioavailability) and treatability of copper in stormwater runoff from copper roofs – until now.
The CDA, in partnership with the International Copper Association, are supporting a study, Attenuation of the Potential Impacts of Copper Roof Runoff by Stormwater Best Management Practices, which was launched eight months ago by scientists at Towson University, near Baltimore. The university is working collaboratively with Mutch Associates, LLC, a New Jersey environmental science and engineering company. As part of the study, the university built a copper-roofed picnic shelter with storm control measures (also referred to as best management practices or BMPs) last summer to assess the amount, biological availability (bioavailability) and treatability of stormwater runoff generated by the structure. The value of the study is that researchers are addressing regulators’ concerns using scientific evidence to determine the removal efficiency and real impact of copper in the environment.
Researchers started collecting data in the last quarter of 2012 by examining the amount of copper in runoff from the copper roof, as well as ways to reduce the copper in this same runoff. Stormwater was collected from the copper-roofed picnic shelter and passed through bioretention planters (soil-filled containers with plants that act as a filter for stormwater runoff) and biofiltration swales (a flat-bottomed channel that uses grass or dense plants and soil to remove potential pollutants).
Natural filtration processes help researchers focus on the treatment of stormwater quality and volume, close to the point where it originates. Data collected from four storm events between December 18, 2012 and February 27, 2013 support two main conclusions. The researchers found that the planters and swales significantly reduced the amount of copper – some 88-99%. In addition, the bioretention and biofiltration systems altered the chemistry of the runoff as it passed through. Model calculations made using stormwater water quality data indicate that the change in runoff chemistry made copper less bioavailable and therefore less likely to cause toxicity.
These results were so encouraging we decided to share our experiences with key people in the Washington State regulatory, municipal, and scientific communities. Scott Tobiason, of Windward Environmental, LLC presented the preliminary findings of the Towson University copper roof runoff study at the local American Public Works Association Surface Water Manager’s Committee. The attendees, representatives from some 30 municipalities, were impressed with our results and found the research a valuable resource as they grapple with copper limits and regulations in their areas. Towson scientists will continue to collect data for another 18 months, but we don’t anticipate results to change much.
We are extremely pleased the data are showing that stormwater management practices will allow the control of copper released from roofing materials in urban environments. This study is just one more example of the safe and sustainable use of copper.