Why are so many fences going up at Folly Beach? Sand-trapping slats to help build dunes as part of renourishment

Debbie and Bobby Pinckney of North Carolina comb the sand for seashells Monday on Folly Beach. Construction is underway to build 5 miles of fencing designed to capture windblown sand and help build new dunes.

FOLLY BEACH — Construction is underway on nearly 5 miles of fencing designed to capture wind-blown sand and help build new dunes on the erosion-scarred island.

The work is the final phase of the $30 million renourishment project that pumped 1.5 million cubic yards of offshore sand onto the beach.

The sand-trapping system includes about 800 V-shaped structures made of wooden slats anchored by three posts. The open end of the “V” faces the beach. The design has proven very effective at growing a sand dune, officials said, and new dunes up to 2 feet tall can be seen in about a month. The west end of the island where the Charleston County park is located is an example of where fencing has built new dunes. “It’s really tremendous how quickly it works,” said David Warren, project manager for the Army Corps of Engineers.

More than 100,000 sea oats and bitter panicum will be planted behind the fencing to help stabilize dune growth.

The sand catchers are built just in front of the existing dune line.

Mayor Tim Goodwin said new dunes may grow 2 to 3 feet above the height of a sand fence. By this summer, the benefits will be apparent. “That’s the plan, if nature cooperates,” he said.

Some 26,000 linear feet of sand fences will be constructed from 10th Street East to the island’s west end at the county park. Completion is expected by the end of March. The same system was used in 2005 when Folly was last renourished, Goodwin said.

Sand fencing has proved its worth in Myrtle Beach, too, Warren said.

The work is happening now so that it will not interfere with turtle nesting and because there are fewer beach visitors.

Team Henry Enterprises of Newport News, Va., and Earth Balance of North Port, Fla., are the contractors for the $500,000 project.

Crews will work Monday through Saturday.

Under state law, sand fencing must be biodegradable and not impede public beach access.

Isle of Palms has had several projects to put in sand fencing and watched emerging dunes grow as a result, said Administrator Linda Tucker.

“Properly installed in the right locations, our experience has been positive,” she said.

“The downside is that if there is a significant storm or the sand fencing begins to degrade, it must be removed before the mesh and the poles with the fasteners get into the surf and become hazardous,” she said in an email.

Sullivan’s is not facing erosion problems like IOP and Folly but it has experience with the sand catchers.

“We have used sand fences in the past with great success,” said Town Manager Andy Benke.

Folly has the worst overall beach erosion in this area because of the effect of the Charleston Harbor jetties, which block the natural southerly flow of sand to the island.

As a result, the city and the federal government entered a 50-year agreement in 1992 for periodic beach restoration, with the city responsible for 15 percent of the cost. The projects happen about every seven years.

Although one renourishment project is drawing to a close, work already has begun on the next one. Goodwin said the new effort is now focused on finding the best source of sand, possibly in Stono Inlet.

Reach Prentiss Findlay at 937-5711