Installing green infrastructure in residential areas can prevent stormwater from flooding sewer systems and significantly curb heavy metal pollution, suggests a new study.
Findings showed that communities that added green infrastructure - systems designed to protect the natural water cycle, such as rain gardens or constructed wetlands - saw a notable reduction in cadmium, copper, nickel and zinc being sent into local waterways. All of these are heavy metals harmful to human health in large concentrations.
Using these systems to manage stormwater flow at the source is imperative to preserving our environment, said Joseph Smith, lead author of the study and a researcher in food, agricultural and biological engineering at The Ohio State University.
"Humans cause a lot of alterations to the environment," said Smith. "So things like rain gardens allow nature to return to how it's supposed to work."
The study was recently published in the Journal of Hazardous Materials.
The project is part of Blueprint Columbus, a 30-year community effort to install green infrastructure into local neighborhoods. The goal is to address sanitary sewer overflows and reduce total suspended solids pollution in runoff by 20%.
After studying the performance of two watersheds in the Clintonville neighborhood of Columbus in managing stormwater pollution for about 3.5 years, researchers found that once installed, green infrastructure systems exceeded expectations, from mitigating peak storm flow rates and pollution to potentially improving residents' well-being and altering local biodiversity. In one particular neighborhood, researchers noted that rain gardens worked to prevent a good amount of heavy metal pollution from entering downstream waterways.
Additionally, because their results were compared to a control watershed - one without green infrastructure - the study was robust enough to determine that the changes the team saw in hydrology, water quality and heavy metals were due to the presence of rain gardens, not seasonal or annual fluctuations in climate, said Smith.
In short, implementing more of these systems in urban areas could make the city's ecosystems healthier and more resilient, said Smith. "Not only does green infrastructure improve water quality, but it also helps cities to be cooler because it adds more green space. The goal is to design spaces where people want to walk around and enjoy beautiful surroundings and experience the many ecosystem services created," he said.
According to the paper, many of these benefits can also be attributed to the design and continued maintenance of the city's connected green infrastructure systems.
"Ohio State's been involved in this project from multiple angles," said Smith. "But what made our study really special is that we could see changes that were happening at the pipe level leading to the stream."
Their results also suggest that engaging with communities to improve public acceptance and functionality of these green measures is of the utmost priority, said Smith. Notably, the long-term success of the project may be achieved by educating homeowners about the benefits of having and maintaining these systems, as some citizens have opposed the addition of green systems to their neighborhoods, raising concerns over safety and convenience.
"Being involved in this watershed-scale rain garden project has made me realize that while there are lots of benefits for the community, there's also more we can do to explain how these projects help individuals who live there," said Smith.
According to the Environmental Protection Agency, investing in green infrastructure also helps create jobs and other lucrative economic development opportunities for the public.
For the time being, Blueprint Columbus is expected to continue retrofitting more areas of the city with green infrastructure through at least 2043. Hundreds of rain gardens already exist across the city, but this work emphasizes how important and beneficial it is to protect the environment through proven, eco-friendly methods.
"Columbus is becoming a leader and model for other municipalities that are facing similar problems," said Smith.
Other co-authors include Kay Bernard, Kathryn Boening-Ulman, Jay Martin, R. Andrew Tirpak, David Wituszynski and Ryan Winston, all from Ohio State. This study was supported by the City of Columbus, Ohio.
