Dredge Material Use Being Tested to Rebuild Marshes

TRENTON – The Christie Administration, in conjunction with the U.S. Army Corps of Engineers and environmental and academic partners, has launched an $8-million pilot project that will evaluate the effectiveness of a new process that uses clean dredge materials to restore salt marshes to make coastal communities more resilient against future storms.
According to a release, the first phase of the project began recently on wetlands in Middle Township, west of Stone Harbor. This approximately one-acre project will be followed next year by larger restoration of 45 acres in Avalon and near the Delaware Bay town of Fortescue.
The project will also study the benefits of using this approach to create a much-needed option for disposal of materials dredged from waterways to keep them navigable. It will also create habitat for endangered wildlife.
“We are very excited about this project and believe it has the potential to provide many benefits in a cost-effective and environmentally responsible manner,” stated Department of Environmental Protection Commissioner Robert Martin. “It has the potential to make coastal communities naturally more storm resilient while helping to solve the problem of where to dispose sediment that builds up and impedes navigation in our waterways. As an added benefit, this will create places for birds to nest, in particular the state-endangered black skimmer.”
The project is made possible by $3.4 million from the U.S. Department of Interior Hurricane Sandy Coastal Resilience Competitive Grant Program. Interior is providing $103 million to help states impacted by Superstorm Sandy to develop strategies to bolster themselves against future storms.
In addition, the Army Corps is providing $2.9 million and nearly $2 million is coming from the state Department of Transportation. The DEP, The Nature Conservancy, Green Trust Alliance, and Rutgers University will provide monitoring and analysis of both ecological and economic benefits of the process.
While wetlands have been constructed and restored in the state for years, this is the first time the state is using a process known as thin layer placement, by placing several inches of dredged clean sediment to raise the level of degraded marshes enough to make them healthy again.
Coastal marshes have been degraded by a combination of subsidence and sea-level rise, making them more vulnerable to erosion, loss of marsh grasses and loss of nesting habitat for birds such as the state-endangered black skimmer. Areas that once were grassy are now open water.
One main goal of the project is to provide the Army Corps, state DOT and communities with a sustainable option to keep navigable waterways clear.
“The re-use of silt and sand in wetlands or on beaches can be a powerful tool in the management of dredged materials,” stated NJDOT Acting Commissioner Joseph Bertoni. “One of the biggest challenges in advancing dredge projects is identifying sustainable, cost-effective and environmentally appropriate locations for dredged material.”
“For the state of New Jersey to take this approach is very impressive,” said Monica Chasten, an Army Corps of Engineers project manager, who is responsible for keeping the Intracoastal Waterway navigable. “It is a sound approach. This is the right thing to do, keeping this clean material in the system
For decades, materials dredged from the back bays and channels have been placed in confined disposal facilities, creating unnatural island-like plateaus in coastal marshes. One such example is Site 103 in marshes southwest of Stone Harbor in Middle Township. It can be seen from Ocean Drive rising like a plateau.
With thin layer placement, several inches of clean sand are pumped onto the marsh, providing a foundation for marsh grasses to take hold. These grasses help to absorb flood waters and storm surge. Higher sand bars are also constructed to provide bird-nesting habitat.
All dredge materials are thoroughly tested and must be clean before being applied to the marshes, said Laurie Pettigrew, a DEP Division of Fish and Wildlife biologist overseeing the project. “If everything goes the way we expect it to go, this will be a big benefit to communities in many ways,” she said.
All of the restoration projects will take place on Wildlife Management Areas managed by the DEP.
The test site behind Stone Harbor, not Site 103, is part of the Cape May Wildlife Management Area and is using sand dredged from nearby Hereford Inlet. Environmental groups will play a key role in monitoring the effectiveness of this process.
“The Nature Conservancy and its partners will study marsh health at the site before and after the restoration to ensure that the expected benefits are occurring, and that the marsh is not negatively impacted,” stated Patty Doerr, director of Coastal and Marine Program with The Nature Conservancy in New Jersey. “We will monitor the effects on birds, fish, vegetation, elevation and hydrology, as well as determine the ability of the marsh to reduce flood damage to coastal communities.”
For information on the Department of Interior’s Hurricane Sandy Coastal Resiliency Grant Program, visit:
http://www.nfwf.org/hurricanesandy/Pages/home.aspx#.U-5mkmP5Qcs and the Governor’s Office news release at: http://www.nj.gov/governor/news/news/552014/approved/20140617b.html
To view photos of the current project in Stone Harbor, visit: http://www.nj.gov/dep/newsrel/2014/14_0085photos.htm