Innovation is the key to success in finding balance between the relocation of dredged materials and ecosystem management.
The Lorain Harbor Section 204 Project Delivery Team (PDT) completed a Feasibility Study to identify geosynthetic containers (GSCs) as an alternative to beneficially use dredged material from Lorain Harbor for aquatic habitat restoration in the Lorain, Ohio area.
Section 204 of the Water Resources Development Act of 1992 authorizes the Corps to implement projects for the protection, restoration and creation of aquatic and ecologically related habitats, including wetlands, or to reduce storm damage to property, in connection with dredging for the construction or operations and maintenance of an existing authorized Federal navigation project.
Multiple design alternatives were developed during the Feasibility Study, which is 100% Federally funded prior to the start of a project.
“During the Feasibility Study, the PDT was struggling with developing an alternative that was implementable (able to be built) under the CAP Section 204 authority (permission)", said Toledo Program Manager Ashley Binion-Zuccaro.
A member of the Fairport and Huron PDTs, Geotechnical Engineer Cedric Wrobel said “The GSC reef concept is being investigated for implementation (buildability) under Section 204 in Fairport Harbor, Huron Harbor, and Lorain Harbor. Filling and deploying (setting up) of the GSCs utilizes the same marine equipment associated with mechanical dredging – making this alternative uniquely scalable (able to be resized) to the volume of material removed from the navigation channel at the time of construction. Placed GSCs are then capped (covered) with stone of various sizes to complete the reef.”
The Environmental Analysis Team worked hard analyzing environmental data to evaluate the GSC alternative and determine that it would stay below the 10 million dollar federal cost share limit set by Section 204.
A GSC is a Geotextile (human-made fiber) container custom created to fit a in split-bottom barge and can be filled with any type of dredged sediment. It’s typically constructed with high strength woven polypropylene (human-made material) geotextile and it may include an inner layer of nonwoven geotextile if needed for holding material. Polypropylene geotextile has a demonstrated history of performance in landfills where they are exposed to aggressive chemicals such as acids and hydroxides. They are not significantly broken down by living organisms or temperature extremes, and they have been placed in Lake Erie under revetments constructed by LRB at Lake County and Athol Springs.
GSCs have never been used as reefs on the Great Lakes; however, they have been successfully constructed as dikes or reefs in other areas of the United States, as well as worldwide. At Red Eye Crossing in Louisiana, a submerged dike was constructed in 1993/1994 at bottom depths of 43-69 feet beneath the surface of the Mississippi River. The Red Eye Crossing Submerged Dike was used to narrow river flow on the river and encourage friction, and it was a safer alternative then traditional rock breakwater that would have posed a hazard to fuel barges running around. At a Marina Del Rey, California location in 1994, 52,000 cubic yards of silty sand contaminated with harmful chemicals were mechanically dredged and placed into barges containing GSCs. They were placed in the shallow water habitat area of Los Angeles/Long Beach Harbor. Narrowneck Reef in Australia was constructed of GSCs in 1999 for erosion control and surfing enhancement. Then the reef was rehabbed/enhanced in 2018 with additional GSCs when some splitting of the original GSCs occurred due to boat anchor spikes.
The Feasibility Study completed by the Lorain Harbor Section 204 PDT has pointed us to a new tool to use for beneficial use of dredged materials. GSCs may one day be a major part of aquatic habitat restoration on the Great Lakes.