Wednesday, August 20, 2014
After withstanding its first summer on Isle of Palms, creators of the wave dissipation system say the wall is working according to plan.
“It's working great,” said Deron Nettles, inventor of the dissipation wall protecting the Seascape Villas on Isle of Palms. “We saw the nor'easter come through earlier this summer. There's only a foot or two of the system exposed now. The system is such a small footprint and is allowing the beach's natural ebb and flow.”
The 144-foot portable wall in place at the Wild Dunes resort is the second version of the system installed at the site and serves as an improved edition of its 88-foot trial predecessor.
Structures like seawalls have been banned under state beach management laws since 1988, but on June 6, South Carolina Governor Nikki Haley signed bill S.1032 to “allow the use of pilot projects to address beach or dune erosion and to allow continued use of these projects under certain circumstances.”
Nettles teamed up with Citadel engineering professor Tim Mays to tweak the system and collect results to verify its usefulness. The new wall is stronger, embedded up to 15 feet deep, while the original was closer to six. Nettles expects to release the summer's numerical results from the improved system later this week.
“First we confirm the structure hasn't been damaged and it hasn't,” Mays said. “We use surveys to look at the volumes of sand in front of the structure, charts and plot graphs to analyze the data. I could not be happier with the results.
“We can actually see the beach is lower around the sandbags and quickly goes up to the other side of the structure.”
The polyvinyl and polyethylene system is designed to break up the energy of storm waves that are causing the erosion while allowing water and fine sand to pass back through the wall.
The flow is intended to mimic that of a natural, unassisted beach. It also allows sand to slowly build behind the wall, another useful step in helping to preserve the eroding shores.
“Realistically, the beach will always need nourishment, but at times, that resource of sand isn't available for certain areas,” Nettles said. “If the resource isn't available, you can install the system to protect the structure until it is. This isn't a permanent alternative, but a tool to work in conjunction with nourishment. And a better alternative than sandbags.”
Following Hurricane Arthur and Tropical Storm Bertha that moved up the East Coast this summer, several of the sandbags that neighbor the dissipation system could be found empty, stuck in the sand and shoreline, while the dissipation system worked properly. Some who helped clean up the bags even placed them behind the dissipation wall, where they'd be protected from the ocean.
“I grew up on these beaches my whole life and I want to protect the area by whatever mean necessary,” Nettles said. “It gets to the point, seeing these bags out there all the time, where it's pretty discouraging. That's one of the reasons I came up with the system.”
The tip of Isle of Palms' extreme vulnerability to beach erosion made it an ideal test site for the system. Ocean and Coastal Resource Management is now encouraging the installation of the system in different areas to collect more data.
Nettles has begun marketing the system in target areas with erosion issues. Garden City, Pawleys Island and Daufuskie Island are among the possibilities. Nettles says one of the system's greatest features is its ability to conform to most any area's needs from the dunes to underwater.
“We're trying to allow homeowners in the state of South Carolina to have one more option to protect their properties,” Nettles said.