A Neighborhood Built Not To Flood

Jul 22, 2016

Civil engineer and designer Joshua Robinson says the vegetation in the marsh system also improves water quality.
Credit Alexandra Olgin

Beaten Path Lane looks like a typical suburban neighborhood street. Houses with square green lawns and large oak trees line the street. But upon closer inspection one realizes the James Island development is missing curbs, sidewalks and gutters. Instead civil engineer Joshua Robinson says there are native juncus grass, cypress trees, beautyberry plants, frogs and dragonflies – all things you would find in a marsh.

Robinson designed this neighborhood a few years ago.

“For many years in subdivisions and neighborhoods engineers have placed storm water management features in the back sort of tucked away,” he says.

Robinson intentionally placed the marsh which is in this case the storm water management system in the front. It follows the curvy narrow road along the nine homes and leads into a stream. This open drainage system was part of his plan to build a subdivision that wouldn’t flood. To do that, he engineered the homes to fit the land.

“There [are] a lot of things about the natural environment that we can’t out engineer,” Robinson says. “We can use our engineering knowledge of science and math to work with the natural world instead of always working against it.”

Houses are only on the left side of the street because it is higher ground. He planned for a curvy 18-foot paved road so he could dedicate more space to plants that soak up water.

“Wetland vegetation ends up doing a really good job of cleaning water and its really cheap,” he says. “Or we can go spend lots of money with concrete structures and lots of additives and chemicals and maybe have the same effect or maybe not”

Robinson's design was put to the ultimate test last October. Much of South Carolina was drenched with a storm system as a result of Hurricane Joaquin. The Charleston area had nearly two feet of rain coupled with unusually high tides. Many streets were inaccessible and water seeped into homes - but not in Robinson’s neighborhood.

“I think that was truly the test.” resident Carole Warrer says.

She lives in a three bedroom home at the back of the development. Her yard has a steep drop off directly into the path of the marsh draining system. She recounts the water flowing through very quickly by her yard into the stream.

““If we got through that, then we should be ok,” she says.    

Researchers at Clemson are interested in how this storm-water wetland works. Daniel Hitchcock and his team are studying how these types of natural systems handle storm-water up and down the South Carolina coast.  

“That natural wetland or marsh system is certainly a way to manage water quality and also manage water quantity, to keep flooding from happening, to give room for flood waters,” he says.  

Hitchcock has been analyzing data from several testing sites and hope to publish results within a few years.

 

Some municipalities are encouraging engineers and developers to work with the land on these low impact developments with faster permits and other incentives. The City of Charleston offers some of those benefits in parts of the peninsula but plans to expand the program.

While, the marsh draining system seems to be working well at Fox Hollow, civil engineer Joshua Robinson says it is important to remember this type of development is an emerging field.

“It’s not perfect. We are working with natural systems that are variable,” he says. “We are searching for a better way, because clearly the way we are doing this isn’t working, it is causing flooding, it is causing pollution.”

Robinson hopes his nine home neighborhood contributes to a more widespread sustainable building approach.

This story was updated Tuesday, August 9th at 11:40 a.m. to include additional audio and photos.