Lorain

Overview

Historically, rivers in Northern Ohio would move sediment through littoral and floodplain wetlands before reaching Lake Erie. Industrial centers and hardened shorelines from development have displaced historic wetlands and created a need for dredging.

Lorain, Ohio. Selected for a 204 wetland creation project, stakeholders found potential in nearshore placement in two general locations; several miles down shore, directly adjacent to a railroad site, and adjacent or within the harbor, itself.

Lorain, Ohio. Selected for a 204 wetland creation project, stakeholders found potential in nearshore placement in two general locations; several miles down shore, directly adjacent to a railroad site, and adjacent or within the harbor, itself.

Site Selection. Four sites were chosen based on desired criteria for further research and development.

Because open lake sediment disposal is illegal in the state of Ohio (Senate Bill 1, 2016), there was a need to devise new innovative and cost-effective options for sediment placement and wetland restoration.

Central Basin, Lake Erie. The mid-sized port cities of the Central Basin are located in historical drowned rivermouths, and as such, present similar challenges and opportunities in their sediment management plans.

Because open lake sediment disposal is illegal in the state of Ohio (Senate Bill 1, 2016), there was a need to devise new innovative and cost-effective options for sediment placement and wetland restoration.

Central Basin, Lake Erie. The mid-sized port cities of the Central Basin are located in historical drowned rivermouths, and as such, present similar challenges and opportunities in their sediment management plans.

Purpose

In the central basin of Lake Erie one dominant type of wetland, drowned rivermouth, has been almost completely replaced by industrial port landscapes. Loss of wetlands affects sediment management, nutrient processing, and flooding mitigation. It also results in the loss of important spawning and flyover habitat. Past practices either placed the sediment in confined disposal facilities (CDFs) or unconfined in the deep open water. Both practices remove the sediment from the nearshore system, preventing its potential use in coastal protection, habitat creation, wave attenuation, and sediment nourishment.
Rivermouth Changes. Based on historical maps, Lorain has undergone several, critical changes resulting from the industrialization of its rivermouth including; river channel widening and deepening, wetland loss, shoreline hardening, and sediment loss.

Concept

A hybrid approach combining both strategies of containment can produce a cost-effective approach to sediment management and wetland creation. Healthy Port Futures proposed the Crescent Sill, a semi-circle-shaped sill structure with a variable crest height that is open on the shoreside. It uses passive sediment management to create ecological complexity and maintain diversity while offering shoreline protection and the potential for recreation. The design allows for disturbances and the redistribution of sediment, seeds, and rhizomes while still protecting selected areas. It encourages wetland establishment and allows for a range of occasional natural disturbances.
Semi-Open Wetland Concept. A hybrid of the two current sediment management options, a semi-open cell wetland merges the ease and cost-effectively of open deep water placement, with wave protection of CDF.

Design

The Crescent Sill adapts to different environmental conditions. It is optimized to minimize stone used in the sill structure, maximize sediment placement and wetland surface area, and allow for variable protection. It can be altered to hold different amounts of dredged material, protect against various predominant wave directions, support different wetland habitat types, and create increased wetland complexity.

View from the Shore. The open-face of the wetland will face the shore, creating both visual interest and promoting recreational accessibility.

View from the Shore. The open-face of the wetland will face the shore, creating both visual interest and promoting recreational accessibility.

Process

We combined physical and computational modeling to test concepts through a process that was nonlinear and iterative, yet rapid. While modern advances in computational modeling open up new possibilities in design, we still find value in working with actual water and sediment to test concepts and simulate conditions on a small scale. We tested different submerged ridge variations against physical simulations of daily, storm, and post-storm conditions. Then, computational modeling helped calibrate the size, scale, and positioning of the design before installation.

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