Posted on August 19, 2024
MOBILE, Ala. – The U.S. Army Corps of Engineers Mobile District has partnered with Mobile County to enhance coastal resilience and habitats using dredged sediments. This collaboration highlights the District’s commitment to sustainable dredged material management practices that benefit the environment and the community.
In February 2024, the District entered into a Memorandum of Agreement with Mobile County to beneficially use dredged material from the Mobile Harbor Deepening project. This agreement formalized their partnership for the Dauphin Island Causeway Shoreline & Habitat Restoration Project, a key initiative to protect and restore critical coastal environments.
“We continue to experience erosion and habitat loss along our coastline, and our coastal communities are susceptible to damages caused by severe weather events and hurricanes,” said Herbert Bullock, USACE Mobile District Dredge Material Project manager. “Beneficial uses of dredge material provide coastal resiliency and habitat restoration.”
Dredged material refers to the sediment, sand, silt, and other organic matter removed from the bottom of water bodies during dredging activities. Dredging is essential for maintaining navigable waterways, such as harbors, ports, and shipping channels, by deepening and widening these areas to accommodate larger vessels. The material removed during dredging was traditionally considered waste and often disposed of in designated disposal sites.
However, as environmental awareness and sustainable practices have advanced, dredged material is increasingly being repurposed for various beneficial uses. Instead of being discarded, it can substitute naturally sourced materials in projects such as land reclamation, beach nourishment, wetland restoration, and protective barriers like breakwaters. By repurposing dredged material, projects can reduce the need to extract new resources, minimizing environmental impacts and lowering project costs.
“The Dauphin Island Causeway Shoreline & Habitat Restoration project was identified early in the planning process for Mobile Harbor as a viable and feasible project for beneficial use due to its location, objectives, and importance to the community,” said Mary Beth Sullivan, USACE Mobile District project manager.
As a critical component of this effort, the District is set to place approximately 800,000 cubic yards of material dredged from the project into the designated containment area along the causeway. This massive volume of dredged material will serve multiple purposes, including constructing and reinforcing rock breakwaters.
Breakwaters are crucial for stabilizing the shoreline, protecting infrastructure, and enhancing local habitats. By repurposing a significant quantity of material, the project minimizes the need for traditional disposal methods and offers considerable environmental and economic advantages.
“Our current goal is to reach 70 percent of our dredged material being used for beneficial use,” said Bullock. “By finding ways to repurpose this material in projects like the Dauphin Island Causeway Shoreline Restoration, we can significantly reduce the overall costs associated with dredging operations. Transporting dredged material to distant disposal sites can be incredibly costly in terms of fuel and logistics. By reusing the material close to where it was dredged, we eliminate much of that expense, making our operations more cost-effective, accelerating project timelines, and reducing our environmental footprint.”
On August 14, 2023, the Mobile County Commission approved a contract to begin constructing the Dauphin Island Causeway Restoration Project. This project will restore tidal habitat along a 3.3-mile stretch of the Dauphin Island Causeway (SR 193), extending from Bayfront Park to Cedar Point. It will use the dredged material to build and reinforce these breakwaters, creating valuable marsh habitats and increasing the resilience of Dauphin Island’s only access road from storm impacts and erosion while safeguarding nearly 300 acres of productive salt marsh habitat, which is vital for the state’s fish, shellfish, and bird populations.
Carter Contracting Services, Inc. was awarded a $26 million contract to construct the rock breakwaters along the causeway. These breakwaters are designed to protect and enhance the marsh and oyster habitats next to the Dauphin Island Causeway, addressing critical habitat loss on the Bay side, where wetlands have been diminished. The Alabama Department of Transportation installed riprap revetment to safeguard this vulnerable transportation corridor.
The core objectives of this initiative include:
Shoreline Stabilization: Breakwaters constructed from dredged sediments will stabilize the shoreline along the Bay side of the Dauphin Island Causeway.
Wetland and Coastal Habitat Creation: The project will create and enhance wetland and coastal habitats, which will provide essential support for local ecosystems.
Resilience Improvement: Restored marsh and oyster habitats will strengthen the coastal environment’s natural resilience, reducing the impacts of erosion and storms.
Dredged material placement for this project began earlier this summer, marking a significant step toward these goals.
With funding from the National Fish and Wildlife Foundation’s Gulf Environmental Benefit Fund, Mobile County, along with coastal design consultants Moffatt & Nichol, has led the design and construction of rock breakwater structures to protect and contain the site. After placing dredged material, Mobile County will oversee the final phase, which includes constructing tidal creeks and planting vegetation to create viable marsh habitat and ensure the project’s long-term success.
This initiative stands as an example of local, state, and federal collaboration, drawing on multiple funding sources to create a project that enhances the environment, protects vital infrastructure, and benefits the local community. The successful implementation of this project sets a strong precedent for future endeavors that aim to balance the demands of infrastructure development with the need for ecological preservation and community well-being.
“As interest in the beneficial use of dredged material continues to grow, this partnership between the Mobile District and Mobile County is timely and forward-looking,” said Sullivan. “It reflects a broader commitment to sustainability and environmental stewardship, demonstrating how innovative approaches to dredged material management can achieve significant ecological outcomes. Using dredged material this way, the District and County set a new standard for future projects, showing that it can meet infrastructure needs while delivering substantial benefits to the environment and local communities.”
