Hurricane Florence left Eastern North Carolina with $2 billion worth of damage and a pressing question: How to reduce the impact of flooding with the next hurricane? That was five years ago. Since then, local, regional and state governments are still building, repairing and renovating infrastructure in response, with an emphasis on green development. Bioswales are one such project popping up across Eastern North Carolina.
In Cape Carteret, a plan for a bioswale is moving forward in the flood prone neighborhood of Ardan Oaks. The neighborhood has suffered from flooding during heavy rains, and not just hurricanes. Most homes were built fewer than 20 years ago. There’s one road leading in and out of the neighborhood.
Over the last few years, a couple of heavy rainfall events flooded an empty lot and covered the road.
“It prevents access for people to get to their homes, prevents access by emergency vehicles, in addition to just being a colossal headache for everyone involved in it,” Frank Rush, the Cape Carteret town manager, said.
In response to previous flooding events, the town brought in portable pumps to remove the water. Bioswale are naturally vegetated areas used to convey stormwater. It’s a simple idea, but these projects are identified in some of the North Carolina Regional Resiliency Plans as low-cost, eco-friendly projects to address flooding in urban areas.
“It may not be as glamorous as maybe some people think it is,” Rush said.
There are three principles of designing stormwater systems, according to Clay Barber with Sound Rivers. He is finishing a bioswale project at Wayne Community College in Goldsboro. The water must be slowed down, spread out and allowed to seep into the ground.
Bioswales do just that. Compared to concrete gutters and storm sewers, bioswales slow water down and allow it to soak into the ground because they are filled with vegetation. Some swales are filled with native plants, but these projects plan to forego that due to maintenance and cost.
The average cost to build 1 linear foot of a bioswale is $58, while one linear foot of a newly constructed storm sewer can cost triple that.
The project at Wayne Community College is nearing completion. There, Barber is repairing an existing 1,700 ft. swale. Due to years of erosion and a lack of maintenance, it doesn’t drain well anymore. It collects but doesn’t move water.
“It was just kind of an eyesore,” Barber said. “It’s a bit hazardous to walk around and work in, and it’s not treating any water.”
For 7 years, Barber has been building natural stormwater projects for schools and colleges across Eastern North Carolina, including a swale at Nash Community College and a rainwater garden at the Epiphany School of Global Studies in New Bern. He shared the strategy behind any good stormwater project.
A bioswale can be installed in medians, cul-de-sacs, along sidewalks, or really anywhere rainwater collects. After it’s installed, Barber and Sound Rivers check up on it for a year afterward to ensure its functioning properly. They also take the time to inform groundskeepers and maintenance staff of how best to maintain it.
It’s just one type of project proposed in the Resiliency Plans. Others include completing assessments of cities’ drainage capacity, prioritizing green development on city properties and rainwater harvesting projects. As local governments look to construct green stormwater infrastructure, Barber says it’s important to not only build green infrastructure but also to maintain it.
“It’s fantastic that these destinations are taking the time to create thorough resiliency plans that include stormwater measures, but if they don’t maintain them, it doesn’t matter, and that’s a trap that everybody fall into.”
