Home > Building, environment > Copper’s Benefits Supported by Scientific Research – Part II

Copper’s Benefits Supported by Scientific Research – Part II

Roof Runoff Study Shows Progress in Mitigating Copper’s Effects on the Environment

By Joe Gorsuch, Copper Development Association (CDA) Manager, Health, Environment and Sustainable Development and Kevin Rader, Project Manager at Mutch Associates, LLC.


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 in the laboratory and outdoors to register chemicals for the photographic industry.

Kevin Rader has more than twelve years of diversified experience in the environmental engineering field. He has conducted both experimental and modeling studies investigating the speciation, toxicity, transport and fate of metals and metalloids in surface waters and sediments. He has been with Mutch Associates since 2009.

In their 2013 article, Copper Roofing:  The Original Green Roof, architects Juan Kuriyama and William Hayes provide an overview of copper use in architectural applications.  Copper roofing is central to the article, and the authors highlight key benefits of the material beyond its aesthetic appeal.  These include:

  • longevity:  copper roofs can function for 100 years or more
  • recyclability:  architectural copper, salvaged copper, and cuttings can be recycled into new copper products
  • low embodied energy, that is, the amount of energy used during its lifetime

The article also describes the “Roof Runoff Scare” referring to concerns raised by the environmental impact study commissioned by the City of Palo Alto, CA that resulted in bans on the installation of copper roofs and gutters.  Subsequent research and updated U.S. Environmental Protection Agency (USEPA) copper water quality criteria support the concept that bioavailable copper in runoff — that is, the portion of the total amount available for uptake by organisms — is the true indicator of the potential for adverse impacts.  This prompts the question “How much of the copper emitted from roofs is available for uptake by organisms and how can that amount be mitigated by on-site management practices and by natural processes beyond the downspout?”  Once answered, architects and designers will be able to weigh the pros and cons of copper use in an objective fashion and make decisions informed by sound science.

With this in mind, in 2012, the Copper Development Association (CDA), in partnership with the International Copper Association (ICA), initiated a collaborative study with researchers at Towson University and consultants at Mutch Associates, LLC, an environmental science and engineering company.  The purpose of the study was to determine the environmental impact of copper roof runoff. Researchers built a copper-roofed picnic shelter on the Towson University campus (near Baltimore) to assess both the amount and quality of stormwater runoff generated by the structure. The university study is titled, Attenuation of the Potential Impacts of Copper Roof Runoff by Stormwater Best Management Practices.  The study was designed to address these concerns with data collected over a two-year period starting in December 2012.

Based on water samples collected from 26 storms, researchers found that diverting rain runoff through planter boxes and swales resulted in a significant reduction in the amount of copper:  94% in planter boxes and 97% in swales.

Towson scientists also conducted toxicity tests using runoff samples collected prior to and after treatment by the planters and swales. Prior to treatment, the survival rate of water fleas (Daphnia magna) added to the runoff samples was negligible.  After treatment, however, the average survival rate for the water flea drastically improved to 82% for planters and 94% for swales. These results are consistent with Biotic Ligand Model (BLM) predictions, a model that since February 2007 the USEPA has endorsed for use in water quality criteria for protection of aquatic life.  The BLM indicates that it is the combination of reduced copper concentrations and shift in the amount available for uptake (i.e., bioavailability) that are responsible for the observed increase in water flea survival.

The bottom line: Copper levels in runoff from copper roofs and the potential for adverse effects can be managed using relatively simple, aesthetically-pleasing, on-site landscape measures.

Towson University researchers are currently analyzing the last of the storm runoff samples.  Final study results will be presented atthe annual meeting of the North American Society of Environmental Toxicology and Chemistry in November 2014 and submitted for publication in one or more peer-reviewed journals by spring 2015.

We are pleased to support scientific research that shows copper isn’t harmful to the environment and continues to be a valued material to the building industry.

For more information about the Towson University study, please contact Joe Gorsuch, CDA Manager, Health, Environment and Sustainable Development, joseph.gorsuch@copperalliance.us.

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