News

Bulldozers give a sense of the width and depth of the renourishment project.
Photos by Michelle Quigley/ Special to The Coastal Star            

More photos from the beach renourishment project  

By Cheryl Blackerby
    
A 355-foot dredge, the most powerful in the country, is pumping sand onto 1.9 miles of Delray Beach’s hurricane-ravaged shore, restoring 1,000 feet of beach at a time.
    Dredging started the first week in March, and even with a nine-day work stoppage due to high seas, the project is scheduled to be finished by mid-April.
    The $9.2 million project is part of a 10-year renourishment plan, which happened to coincide with the aftermath of Hurricane Sandy’s surges that took away sand and carved out chunks of beach, forming escarpments up to 5 feet high.
    By the end of the project, the beaches beginning 1,000 feet north of Atlantic Avenue and running south to several hundred feet beyond Atlantic Dunes Park — will be fortified with more than 1.6 million tons (1.2 million cubic yards) of sand.

Avoiding reef damage
    While there have been no reported problems with the Delray Beach project, state officials say they found damage to a reef 17 miles to the north. When the dredge was towed from Palm Beach Inlet to Delray Beach, tugboat cables dropped and were dragged across Flower Garden Reef, a popular dive site a mile off Palm Beach, according to the Florida Department of Environmental Protection.
    Two dive vessels and one local researcher reported the damage March 3 and the FDEP’s Coral Reef Conservation Program surveyed the damaged area March 6, said Mara Burger, FDEP spokeswoman. Jena Sansgaard, the agency’s reef injury prevention and response coordinator, is inspecting the damage.
    “The assessment of this injury is ongoing, therefore we do not know how much reef was damaged,” Burger said. “This is a long-term process and can take between six months to a year, or in some cases longer.”
    Barrel sponges were damaged, soft corals were displaced and some hard corals have abrasions, according to Jeanmarie Ferrara, spokeswoman for Great Lakes Dredge & Dock, the company that owns the dredge. The company has hired marine biologist Bruce Graham to give an assessment of damage and oversee repairs.
    The Army Corps of Engineers notified the company of  “pockets of reef injury within a three-mile area,” Ferrara said. The company and the FDEP began an “accelerated assessment recovery and remediation program on March 8 that involves collecting and attaching the sponges in a secure location on the reef and reattaching the barrel sponges to a suitable substrate so they can reestablish themselves.”
    Reef damage is unlikely in the Delray Beach project because the dredge and tow boats must pass through a gap in the limestone reefs, and not over the reefs, said Richard Spadoni, executive director of Coastal Planning and Engineering in Boca Raton, the company that is administering the project.
    CPE representatives have been on the dredge each time it was moved into the project area through the reef gap, he said.
    “We monitor the dredge tracking screen as movement occurs to see that the dredge stays within the designated corridor through the reef gap and also never goes over any of our reefs. In fact, we have a significant buffer zone around the reefs so that the equipment stays hundreds of feet away from the reefs,” Spadoni said.
    The sand for Delray Beach is pumped from “borrow areas,” between the limestone reefs and the beach, about 2,500 feet from shore. Project managers say they chose the areas after an intensive geotechnical investigation including surveys and analysis of sand extracted in “sediment cores,” taken up to 20 feet deep to show layers of sediment.
    The idea is to match the beach sand as closely as possible. It comes out gray but bleaches out over time and mixes with other sand. The FDEP has to approve the sand in the borrow areas.
    Some borrow areas have been previously dredged; the last major dredge was in 2002, though more sand was taken in 2005 in response to hurricanes. The deepest excavation is 57 feet from the ocean surface. There are buffered areas near the reefs and borrow holes that can’t be dredged because of scattered metallic objects — modern debris or metal from the S.S. Inchulva, a 386-foot British steel-hulled steamship that wrecked near the beach in 1903. The metal bits are buried in deep sand and can’t be identified.

Dunes best option so far
    Delray Beach is lucky to have abundant sand just offshore.
    “Miami doesn’t have our plentiful reserves of sand,” Spadoni said. “Miami may have to borrow from the Bahamas at some point. They are close to depletion.”
    But Delray’s sand reserves won’t last forever, he said. “Sand does not come back into the borrow holes, and we are depleting the sand. But Delray will be OK for the next 40 or 50 years.”
    Sand can’t be dredged east of the reefs because of the deep water.
    At a recent Delray Beach City Council meeting, Commissioner Al Jacquet asked Matt Jack, project manager for Great Lakes Dredge and Dock Company, if he knew of a permanent solution to the beach erosion problem.
    Jack didn’t have an alternative solution, and wasn’t expected to since he’s in the dredging business; but what Jack and his company are doing is as close as Delray Beach can get to a permanent solution.         

Other options were tried and failed. In the 1960s, Delray Beach had no beach, and the water often lapped the pavement of A1A. In desperation, the city installed “waffle revetment,” interlocking concrete blocks on the beach, which effectively kept people off the beach, didn’t help with erosion, and eventually collapsed after water undermined the structure.
    In late 1973, the city started pumping sand onto the beach, building dunes and planting sea oats and other vegetation. The beach grew wider because the dunes effectively captured sand. During Sandy’s surge, the dunes protected the beach and homes.
    “Delray Beach has one of the largest dune systems in South Florida,” Spadoni said.
    Calculating for regular dune and beach renourishment is the closest anyone has come to a permanent solution, he said.