Absecon Island Beach Reourishment Brings Major Benefits (USA)
The communities along the New Jersey shoreline have suffered significant storm damages from nor’easters and hurricanes and are at risk to suffer further damages from coastal storms.
The project is designed to reduce the damages to homes and infrastructure from the waves, high tides and storm surges associated with these events.
Atlantic City and Ventnor City are important and economically vital coastal communities that serves as a national destination for tourism and recreation. The health and productivity of a coastal community and its beachfront are linked. This project will not only act to reduce the damages to the oceanfront infrastructure, but will protect the island from devastating erosion and damage. In turn, this will help the communities continue to thrive as a destination for beach patrons, surfers, fishermen, and wildlife enthusiasts.
Construction of the Brigantine Inlet to Great Egg Harbor Inlet, Absecon Island New Jersey Storm Damage Reduction Project, is authorized by the Water Resources Development Act of 1996. A Project Cooperation Agreement to construct the project was signed July 2003 with New Jersey Department of Environmental Protection.
In 2004, the U.S. Army Corps of Engineers’ Philadelphia District and the New Jersey Department of Environmental Protection completed initial construction at Atlantic City and Ventnor City. Periodic nourishment is scheduled for a 3 year cycle. The project scheduled to be constructed in the spring of 2012 represents the first full-scale renourishment of the project.
Additionally, in 2009, severe nor’easter events damaged portions of the constructed project. In June 2011, with funds from the Flood Control & Coastal Emergency, (FCCE), program, the Philadelphia District completed an emergency repair of the Atlantic City and Ventnor City beaches to the pre-storm conditions.
The current periodic nourishment involves placing 1,325,000 cubic yards of sand onto the beach across the entire municipalities of Atlantic City and Ventnor City. The project began in March and is slated for completion in June. The total cost of the project is $18.1 million and is cost-shared with the state and local governments.
To put the amount of sand in context, a full-sized truck bed is 2 cubic yards, so 662,500 truckloads of material would be required to provide enough sand to construct the project design template. The design template includes a berm (flat beach area) at an elevation of +8.0 NAVD, with a 10 horizontal on 1 vertical foreshore slope, (the incline into the water), and a new protective dune. The protective dune will have a crest width of 25 feet wide at an elevation +22.00 NAVD, or 14 feet higher than the existing beach berm elevation. The contract also includes pedestrian, vehicular and handicap dune crossover construction, dune grass planting as well as sand fencing.
The borrow area for the current project is located at the entrance to Absecon Inlet at the northern end of the project. Weeks Marine Inc. is the contractor for this project and will be using a hydraulic cutter head type of dredge to accomplish the beachfilling. This type of dredge is anchored in the borrow area and churns the material from the bottom and then the sand is pumped through pipeline onto the beach. This project will also employ at least one booster pump. After the fill is discharged, it is bulldozed into the design template developed by USACE. The Corps calculates the amount of cubic yards placed by completing before and after beachfill surveys.
Beachfill operations take place 24 hours a day and 7 days a week throughout the project. Weeks Marine will close approximately 1000 foot sections of the beach at a time while completing work in the area, and then move in a southerly direction as each section is completed. The project length is approximately 5.1 miles long stretching from Absecon Inlet to Fredericksburg Avenue.
• Dredge Ellefsen – hydraulic dredge (cutter section dredge; flat bottom barge with no propulsion, uses anchors and chains to pull itself through the borrow area)
Dimensions: Length: 206 ft
Breadth: 62 ft; Depth: 12.5 ft
Overall Length: 277
Draft: 9 ft
Dig Depth Range: 11 to 70 ft
Suction Diameter: 34 in
Discharge Diameter: 30 in.
Machinery & Power:
Total Installed Power: 13,350 hp
Cutter head screen: (1.25” diameter) to screen material before intake.
• Shore pipeline, 30 ft sections of metal pipe pushed together
• Multiple Large Bulldozers and Loaders
• Baskets to screen material at discharge end of piping. Screen is 0.75 inches x 0.75 inches.
Dredging Today Staff, June 7, 2012; Image: usace