Crews lay pipe, ready for beach fill and groin at island's eroding heel

tbarton@islandpacket.comDecember 17, 2011 

  • Question: Why renourish?

    Answer: A wider beach provides a better buffer to protect oceanfront homes, villas and businesses from coastal storms, and it's a recreational amenity for beachgoers. A wider beach also ensures a protected and sustained natural environment for endangered sea turtles and sea birds.

    Q: What is the beach renourishment process?

    A: Years before the start date, engineers surveyed the ocean floor off the island's coast to find "borrow" areas with the right sand consistency and quality for the beach. A spiral-tipped "cutterhead" dredge is placed offshore above the borrow site, cutting into the ocean floor and drawing sand into a pipe. Tugs move the dredge into position. The sand is pumped via a "jack-up booster" through an long pipeline that runs both under and above water and dumps the sand on the beach. The sand and sea water slurry is passed through a diffuser, spraying the mixture onto the beach. Dikes allow the water to return to the ocean while the sand settles on the beach. Bulldozers push the sand into the right spots and shape it to the proper elevation. Survey boats verify the quantities and placement of sand. More pipes are added to the line so the project can progress along the beach.

    Q: How will renourishment affect beachgoers?

    A: Construction will take place 24 hours a day for two months, and crews will work in 1,000-foot sections at a time. The site will be closed while work progresses, but beach access ramps will accommodate visitors to the beach. As soon as one section is finished, the equipment will move down the beach, and the newly renourished section will become accessible. The dredge picks up small amounts of shell and mud with the sand, which is why newly placed sand often appears dark. The sun oxidizes the non-sandy material within a few days, and the beach eventually turns as light as it was before.

    Q: How will the project affect sea turtles and sea birds on the beach?

    A: The project will avoid sea turtle nesting season on Hilton Head Island, which runs May 1 to Oct. 31. The piping plover, a small, threatened bird, winters on a section of the beach. Town staff will monitor, document and catalog the birds' activity on the island during the project to ensure the wintering population is maintained.

    Q: What happens after the project is complete?

    A: Beach renourishment is an ongoing process. The town has more than 50 beach-monitoring stations to keep track of how much sand has been lost or gained from recent projects, and aerial photos are taken annually to monitor changes to the coastline.



    Source: The Town of Hilton Head Island and Hilton Head Island-Bluffton Chamber of Commerce


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Crews began laying and submerging pipe and prepping machinery Friday for a $9.8 million project to rebuild and protect Hilton Head Island's heel.

This week, workers will begin pumping about 1 million cubic yards of sand from offshore onto a one-mile stretch between the Westin Resort and the Beach House in Port Royal Plantation, town public projects and facilities director Scott Liggett said.

The work aims to combat a decade of erosion that has claimed about 80 to 100 feet of beachfront a year. Left unchecked, the erosion could threaten oceanfront property, town officials said.

But keeping the shoreline in good shape isn't easy.

The town also will build a 700-foot-long wall made of granite boulders to stabilize the eroding beachfront. After bulldozers finish pushing sand into the right spots for the first 1,000-foot section of beach, crews will start hauling 12,000 tons of boulders for the groin. The $1.2 million structure will trap sand that normally would be lost to coastal drift, but it will also allow some sand to move over its top so as not to starve other areas of the beach, Liggett said.

"It doesn't mean the sand we place won't move -- it certainly will -- but we hope the groin will provide us a degree of stability and lower the loss rate we would otherwise see," he said.

The groin will be buried, so people won't have difficulty walking or biking along the beach, but areas jutting into the water will be exposed, Liggett said. Boaters and swimmers will need to beware. The town is discussing potential markings and lighting to alert people.

It will be the third groin the town has built but the first for the island's oceanfront.

The town built a groin in spring 2009 at the south end that worked faster than predicted and prevented more sand from being washed away. Liggett hopes that could bode well for the island's heel.

At the toe, the mound of granite boulders at the inlet to Braddock Cove near South Beach has moved the high-water line seaward almost 80 feet and stacked sand nearly four-feet high, he said. The sand would have otherwise built up at the entrance to the inlet, Liggett said.

Work at the heel was to begin in January 2010, but problems with permitting, moving equipment and weather delayed the project.

The postponement, though, might have been for the best.

"The beach will be less crowded now that it's winter," said Dan Davis, general manager of the Port Royal land owners association.

"We are looking forward to the project. It's a busy stretch of beach used by both our residents and visitors," Davis said. "There's about 100 to 150 feet of solid beach left. (Erosion) is not imminently threatening, but we wouldn't want to wait any longer. ... The sound of the bulldozers beeping in the night will be a welcome sound. It's music to our ears."

The beach fill is a 24-hour-a-day, two-month process. Construction of the groin is expected to be completed by May 1.

Follow reporter Tom Barton at twitter.com/EyeOnHiltonHead.

Related content:

High tides and winds erode Hilton Head beaches: Nov. 1, 2011

Island council awards contract for Port Royal beach renourishment, OKs borrowing: Aug. 2, 2011

On Hilton Head's heel, sand continues to be lost to nature, permit delays: April 16, 2011

Hilton Head officials encouraged by south end groin success as they plan new structure: Nov. 1, 2010

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