FOLLY BEACH — A rock- picking machine has been at work sifting out clumps of hard material mixed-in with the sand pumped from offshore for the city’s $30 million beach nourishment project.
The U.S. Army Corps of Engineers, which oversaw the project, says the “cemented material” may wear down over time and disappear. The project contractor, Great Lakes Dredge and Dock Co., will run the rock-picking machine at the beach for another two weeks, said Brian Williams, chief of the program and civil works management branch for the Corps Charleston District.
“We really don’t have the contract vehicle to keep Great Lakes out there indefinitely,” Williams said.
On Thursday, the machinery was idled near the pier next to a pile of sand and rocks. The machine digs sand and sifts out rocks that look like fossils, said Mayor Tim Goodwin.
Rock-like material mixed with the sand is a problem for the length of the renourishment completed last year. The city hopes to identify another, cleaner source of sand for its next beach restoration project, Goodwin said.
The rocky materials have shown up on the beach at the county park on the south end of the island. Sand in the ocean typically flows in that direction which could mean the rocks are from the city beach, said Tom O’Rourke, executive director of the Charleston County Parks and Recreation Commission.
“I think all of the (beach) stones on the entire island are the result of the city renourishment,” O’Rourke said.
The stones are “not a showstopper,” he said.
On Thursday, most of the rocks at the park beach were located past the high-tide line.
“I think it takes away from the beauty of the beach. You have to be a little more careful about where you are stepping. I was wondering if it was asphalt,” said Janice Hart of Boston.
The park commission completed a separate beach-restoration project that drew from the Stono River Inlet. The park beach had clean sand when that work was finished, O’Rourke said.
The county park has been named one of the nation’s “Best Restored Beaches” by the American Shore and Beach Preservation Association, an advocate for renourishment projects and other beach planning. It joins beaches in Port St. Lucie, Fla., Galveston, Texas and Santa Monica, Calif.
The PRC in 2013 dealt with environmental concerns and diverted $3 million from other funds to shore up the severely eroded and closed park when the mandated and overdue Folly renourishment was not funded because of federal budget crimps and divisive politics. The overall beach renourishment finally took place in 2014.
“The loss of the county park access was a loss to the whole community, said Lee Weishar, who chaired the committee that chose the best restored beaches. “This project gave them back their recreational beach and had the added benefit of adding sea turtle and pelican habitat.”
Before the city beach renourishment began, sample borings of the ocean site where sand was dug showed that it was good-quality material.
“Unfortunately it wasn’t as clean as we thought,” said Glenn Jeffries, Corps spokesman.
A decision to move forward with digging a new area of the ocean bottom to supply sand for the city beach renourishment was an “educated guess” based on available information obtained through a number of sample borings.
More extensive sampling would have added millions of dollars to the cost of the project, she said.
The federal government paid 85 percent of the renourishment cost and the city the rest.
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