Posted by Stephen Beach on January 30, 2012

Crucial Information for Engineers and Architects: What is a bioswale?

See other great resources on: Boardwalk Design, Boardwalk Construction

what is a bioswale crossing 1 what is a bioswale permatrak 

In November 2011 Rodgers Builders installed a PermaTrak boardwalk over a bioswale in Thomasville, NC. This elevated boardwalk connects the frontage sidewalk and main entrance of Piedmont Crossing Retirement Community.

During our daily ritual of running through our work day during dinner, I told my wife that the contractor had completed work on the Piedmont Crossing bioswale boardwalk. She stared back at me blankly. That's when it hit me. I was talking "consultant" again; she likens it to a foreign language. To help other folks, including my wife, I've decided to create a few blog posts to explain what in the world I am blabbing about all day.

So what is a bioswale?

A bioswale is a landscaping feature designed to capture pollutants and runoff when it rains. Generally, a bioswale is a linear "garden" that stores stormwater runoff in areas like parking lots.

You have probably seen vegetation or trees planted in small ditches in parking lots. It makes sense that the gradual sloping sides on these bioswales would help correct rainwater, preventing major flooding from occurring in the lots. Those bioswales are strategically engineered to keep you from having to slosh through inches of water on your way into the grocery store.

Bioswales are often a nice alternative to installing a number of storm sewers. Their natural appearance has a nicer aesthetic, and studies have shown if bioswales are properly built, they can protect the environment.

If designed correctly, a bioswale can trap a handful of pollutants, metals and silt picked up off cars, buildings, or surrounding and carried by the rain. Think of all the oil, grease and small bits of garbage that your car can drop off in a parking lot-where does it all go? A bioswale can capture this runoff and break up the pollutants before releasing any water into the environment. It acts as a natural filtering system.

A second use for a bioswale is to prevent contaminants such as pesticides from being carried into natural habitats including rivers. Once again, this filtering system protects the surrounding environment from absorbing this pollution.

Engineer-types may also refer to bioswales as vegetated swales, grassy swales, bioretention areas or filter strips. If you would like more information-check out Upper Des Plaines River Ecosystem Partnership's website:

bioswale crossing permatrak resized 600

bioswale crossing piedmont resized 600

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About This Blog

The PermaTrak boardwalk blog articles are written for landscape architects, engineers, and agency or municipality professionals.

We aim to provide educational resources for designing and building boardwalks, pedestrian bridges, trail and greenway systems. 

By reading our weekly posts, you will deepen your understanding of boardwalk design, cost estimates, and construction practices.