The Florida Department of Transportation is wrapping up a $117 million secant seawall project to protect parts of the Jimmy Buffett Memorial Highway, a major coastal road, from future hurricane damage.
[Above photo by Florida DOT]
The highway, also known as State Road A1A, runs for 339 miles along much of Florida’s Atlantic coast. The project consists of two seawalls in Volusia and Flagler counties, areas where the highway was heavily damaged during Hurricanes Ian and Nicole in 2022.
That roadway serves as “a critical transportation corridor for residents and businesses, as well as a hurricane evacuation route,” said Cindi Lane, Florida DOT regional public information director.
Each seawall is 1.3 miles long, with the northern seawall straddling the two counties and the other about six miles south in Volusia County. They were built by drilling alternating and overlapping holes of about 38 feet and 18 feet into the beach. Concrete was pumped into the holes, and the deeper piles were wrapped with fiberglass cages, resulting in a solid wall that is expected to last at least 50 years.
Crews capped the piles with concrete before trucking in more than 123,000 tons of sand to form sand dunes to cover the walls. Florida DOT is planting more than 142,000 native plants on the dunes to give them a natural look and to prevent beach erosion, Lane noted.
“From the road, you wouldn’t know there’s a seawall there because all you see is a sand dune,” she pointed out. Even if a storm wrecks the sand dunes, the underground seawall should protect the road.
“Florida DOT has committed to placing new sand to cover the wall as needed as part of its maintenance program,” Lane added. “This will help to ensure the wall performs as expected well into the future.”
The agency chose to utilize secant wall construction instead of sheet piling because secant piles can be driven deep into bedrock to provide more stability, she noted. That also allows for a smaller design footprint with the secant pile construction process also quieter as well.
The eastern side of this part of A1A has no development, giving it “absolutely gorgeous ocean views,” but the direct exposure to the Atlantic also leaves the highway “more vulnerable to erosion and damage by hurricanes and northeasters,” Lane said.
Florida DOT repaired damaged portions of A1A immediately after those 2022 hurricanes, but the department recognized it needed a proactive approach to make the highway more resilient, Lane said. The agency put together a “Resiliency Strike Team,” which included experts from Florida DOT, the U.S. Army Corps of Engineers, Florida Department of Environmental Quality, and local government.
“The mission was to protect the road and protect the beach,” Lane noted.
After Hurricane Matthew in 2016 tore up A1A in northern Flagler County, Florida DOT built a seawall to protect the highway, and it seemed to be holding up well, she pointed out. The team explored several options and decided to pursue two projects – the seawalls in Volusia and Flagler counties, and a beach re-nourishment project on Flagler Beach.
The Corps of Engineers – with Florida DOT providing part of the local match money – headed up the beach re-nourishment project, which pumped sand from the ocean to the shore to widen the beach. Florida DOT then took the lead in the seawalls project.
The agency has finished building the walls and caps on both seawalls and is almost finished shaping the dunes and plantings.
One sea turtle nest in the construction zone has temporarily halted the dune shaping on the north seawall, Lane said.
During sea turtle nesting season, which runs from March through October, construction work can only begin each morning after an approved turtle nest inspector has surveyed the area to identify any nesting or hatching activity. If a nest is found, no work can occur within 10 feet.
Florida DOT added that the entire project is expected to be completed by early 2026.
