Massive loads of mud, silt and sand are being used in a ‘design-with-nature’ project to restore a portion of New Jersey wetlands
By Andrew S. Lewis, for NJ Spotlight News
When the state began construction on the New Jersey Wind Port, an offshore wind marshaling and manufacturing hub located in Salem County, in 2021, it was faced with the question of what to do with some 600,000 cubic yards — about 45,000 dump trucks’ worth — of mud, silt, sand and other sediment that needed to be dredged from the bottom of the Delaware Bay.
In a previous time, the material would have been jettisoned into a distant confined disposal site or even barged out to sea and dumped overboard. For the Wind Port’s dredged sediment, however, the state’s departments of Transportation and Environmental Protection, along with the Economic Development Authority, looked five miles to the northwest, toward a 365-acre tract of severely sunken marshland within Abbotts Meadow Wildlife Management Area. Embracing a relatively new method of wetlands restoration, the state decided to pump the sediment onto the marsh to build it back up — like a Jersey Shore beach replenishment project, but for the benefit of nature.
Rebuilding a sinking wetlands
“The marsh platform had degraded and reverted to open water,” said Scott Douglas, dredging program director for the Transportation Department’s Office of Marine Resources. “We needed a place to put material, and [DEP] was actively looking for a partner to provide them with a large amount of sediment, so we went in, evaluated the hydrology, and figured out how much material we would need to bring the whole site back up to a level that would support healthy marsh.”
By the time the first parcel of Abbotts was sold to the DEP in 1994, centuries of salt hay farming, diking and other ad hoc attempts to hold back tidewater had altered the natural hydrology of the marsh. By 2021, some sections had subsided by as much as 6 feet. The Spartina grasses and other high-marsh habitat had been overwhelmed by saltwater inundation and had died back, taking with them nesting and foraging habitat for fragile species like the northern harrier, black rail and saltmarsh sparrow.
Largest wetlands project of its kind in NJ
The state partnered with WSP, a national environmental consulting and engineering firm, which began designing what is now the largest ever “beneficial use” project to date in New Jersey. Beneficial use takes a page from the “design-with-nature” philosophy, which is based on the idea that the human-built environment should be shaped to complement, rather than resist, the forces of nature, especially water. At Abbotts, that meant redistributing the Delaware Bayshore’s own marshland sediments to those areas that have not been able to keep up with the rate of sea level rise.
“This is the first time the state, with its partners, has been able to do such a large channel project in coordination with a restoration project,” said Katie Axt, WSP’s Abbotts project manager. “It’s great to see the state normalizing sediment as a resource.”
Pumping began last November. According to Douglas, two dredges equipped with 3,000 horsepower pumps steadily moved the slurry of sediment and water through a 24-inch pipeline for the next few months. By January, the project site had been graded into varying elevations to mimic the landscape that had once been there. The hope was that, by summer, the new marsh would begin to show signs of life. The goal, Axt said, was “to create a matrix of habitats.”
Related:
Abbotts Meadow Wildlife Management Area Marsh Restoration
Wetlands Institute video
Abbotts Meadow Wildlife Management Area
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