ISLE OF PALMS - Fast-moving dump trucks greet beach visitors to Wild Dunes at the east end of the island as the city wages another battle in its war against erosion.
This time, a new strategy is being employed. City Council authorized $130,000 to build a 100-yard-long natural bridge from the mainland to a sand-rich shoal exposed at low tide.
"You don't see that every day. It's worked out very well," said Dave Kynoski, chief operating officer for the Wild Dunes Community Association.
Trucks drive on the sand causeway to the shoal where a back hoe digs material to haul back to shore and dump in erosion hot spots. There, a bulldozer spreads the sand.
The project helps along Mother Nature by speeding up the process of the sand bar attaching to the beach. A shoal sitting offshore can exacerbate erosion, Kynoski said.
"The shoals have always been the real cause of the focused erosion," he said.
The shoal being tapped has an estimated 1 million cubic yards of sand, enough to fill thousands of dump trucks. But the giant mass of sand only moves 600 feet per year. It has been creeping shoreward for about six years and is just now beginning to attach to the island, officials said.
Instead of waiting for the beach-saving sand, the city, engineers and contractor built the causeway for trucks to reach the shoal. The operation happens within a few-hour window on either side of low tide.
The island from Dewees Inlet to 53rd Avenue is considered an unstable erosion zone because of the irregular way sand moves from the inlet delta to beaches down shore.
"There's not a whole lot that can be done to reduce that impact," Kynoski said.
Millions of dollars have been spent to repair the damage. The city spent $200,000 for the current $1.2-million project, which began in November and is expected to last another 30 days. The balance of the cost is funded privately by groups such as the Wild Dunes Community Association. The city manages the project.
Mayor Dick Cronin said erosion worsens as a sand bar approaches shore, but once it attaches to the coastline the sand spreads along the beach.
"What we're doing is enhancing that spreading of sand. We're making it happen quicker," he said.
In addition to the offshore work, enough sand to fill hundreds of dump trucks is being dug along 1,200 linear feet of healthier beach between 53rd and 56th avenues. It is also being dug from 1,600 linear feet of shoreline in front of Beach Club Villas, Mariner's Walk and Shipwatch Villas, according to a city project map.
Trucks haul the sand to be spread in front of Seascape, Ocean Club Villas and the 18th hole of the Wild Dunes golf course. Sand is also being carted to another hot spot in front of Beachwood East.
An off-duty police officer patrols the affected stretch of shoreline to keep beach walkers out of the work area.
The city has permits to dig and spread up to 500,000 cubic yards of sand at the eastern end of the island. A project that spread 87,000 cubic yards was completed in 2012. The current effort is expected to involve more than 150,000 cubic yards.
Even with the completion of the current project, erosion will continue until the shoal fully attaches to the shore in the next year or two.
In the meantime, there has been discussion of whether the city should begin the application process for another major beach nourishment project like the one completed in 2008 which involved offshore dredging and pumping sand ashore. Permits for that kind of work can take two years to acquire, Cronin said, but the city has made no move in that direction.
The city will have more revenue for erosion problems because its voters approved a November referendum that authorizes an additional 1 percent accommodations tax that is expected to generate $800,000 yearly for beach maintenance.
Voters at erosion-plagued Folly Beach also authorized a 1 percent increase in the accommodations tax in a referendum held Dec. 2. The new tax on overnight visitors is expected to generate $320,000 annually.
Folly Beach Mayor Tim Goodwin has expressed concern that the Charleston Harbor deepening project will worsen erosion on the island. Folly has suffered a significant loss of beach because the jetties block southerly sand flow that instead stacks up at Sullivan's Island, which has gained nearly 100 acres of "accreted" land, officials said.
Goodwin wrote letters to the U.S. Army Corps of Engineers expressing worries over whether the effect of extending the harbor entrance channel three miles seaward was being adequately considered in the project permit review process. An Army Corps spokesman has said it will address Goodwin's concerns in its final environmental impact statement on the project.
Because the jetties cause erosion at Folly, the federal government has authorized millions of dollars to renourish the island beaches including an effort completed last year.
Reach Prentiss Findlay at 937-5711