Posted on December 2, 2024
After the Atlantic Ocean breached the dunes and spilled onto Coastal Highway multiple times earlier this year, emergency dredging is finally underway to replenish the severely eroded north side beach in Delaware Seashore State Park.
The project will dredge up to 400,000 cubic yards of sand from the Indian River Inlet Flood Shoal, just west of the Charles W. Cullen Bridge, to replenish up to 5,000 linear feet of the north side beach, a Department of Natural Resources and Environmental Control news release said. The dredged material will be screened and then transported via pipeline to the north side beach, where it will be graded.
The replenished dune will be 25 feet wide and 16 feet tall, the news release said, while the beach will be about 100 feet wide and 9.2 feet tall (about 7 feet above the average high tide). Replenishment will begin along the jetty and extend northward.
The north side beach is expected to remain closed throughout replenishment. Mariners are urged to be cautious in the area of the inlet and to maintain a safe distance from dredging equipment.
Why emergency replenishment is necessary
The area of the Indian River Inlet, within Delaware Seashore, is highly complex. The inlet serves as a connection between the Atlantic Ocean and the Indian River and Rehoboth bays. Coastal Highway, a critical evacuation route, crosses the inlet via the Charles W. Cullen Bridge. On either side of the bridge, the road runs through narrow strips of land between the ocean and the bays.
The dunes are Coastal Highway’s only protection from the Atlantic, and they were breached multiple times this year on the north side of the inlet. Though the area of the highway that flooded was at the foot of the bridge, Department of Natural Resources and Environmental Control and Department of Transportation representatives have said the bridge itself is not at risk.
The north side beach is particularly susceptible to erosion because the jetties on either side of the inlet interrupt the natural flow of sand. Sand typically flows northward, but at the inlet, sand blocked by the jetties builds up on the south side.
For years, the Department of Natural Resources and Environmental Control relied on a bypass system to pump sand from the south side to the north side. Though the bypass was never intended to be the sole solution for the erosion on the north side, department representatives said, it broke down in 2019.
The decision was made to convert the pump from diesel to electric, but then the pandemic happened and delays ensued. The bypass system is finally set to be repaired next year, but since 2019, the department has spent hundreds of thousands of dollars, at least, to truck sand to the north side. It wasn’t enough to keep up with the erosion, nor was the decision to use riprap to fortify the dune.
The only option left was dredging and replenishment. The Department of Natural Resources could have requested federal funding for replenishment as early as January 2023, according to John Kane, the U.S. Senate Environment and Public Works Committee’s director of infrastructure, but the first time they did so was May of this year, and that request was denied, according to Department of Natural Resources spokesperson Nikki Lavoie.
It took a dune breach in August, the year’s second, for the state to come up with $15 million in funding for emergency replenishment. Shortly after Gov. John Carney made the announcement, U.S. Sen. Tom Carper announced $10 million in federal funding to “implement a long-term plan to secure the dunes and protect the infrastructure surrounding the Indian River Inlet Bridge.”
The U.S. Army Corps of Engineers expedited the permitting process and is now scheduled to perform additional dredging and replenishment at Delaware Seashore in 2025, the DNREC news release said.
