At the City Commission meeting on April 13, 2016, the Mayor and City Commission referred a discussion to the Sustainability and Resiliency Committee (SRC) regarding how green infrastructure, including living or hybrid shorelines, can complement grey infrastructure in our on-going climate adaptation work. This item was sponsored by Commissioner Micky Steinberg. Following a presentation on January 18, 2017, the SRC requested quarterly updates on this discussion item.

Living shorelines use a combination of bank stabilization and habitat restoration techniques to reinforce the shoreline, minimize coastal erosion, and maintain coastal processes while protecting, restoring, enhancing, and creating natural habitat for aquatic plants and wildlife. Living shoreline projects are constructed using a variety of structural and organic materials, such as wetland plants, submerged aquatic vegetation, oyster reefs, coir fiber logs, sand fill, and stone. In addition to shoreline stabilization and erosion control, living shorelines provide added benefits, such as reduction of wave energy, absorption of storm surge, improved water quality via filtration, protection of riparian and intertidal resources, and creation of aquatic and terrestrial habitat.

Despite their multiple benefits, living shorelines are not effective in all conditions, especially in high energy environments where increased shoreline armoring is more effective in stabilization and erosion control. There are several considerations, including existing site conditions and future maintenance and monitoring needs, which must be taken into consideration when planning and implementing living shoreline projects. The City has several seawall projects in the planning and design phases that present an excellent opportunity to use green infrastructure to complement grey infrastructure solutions. Living shorelines created as part of this project will not only add habitat in Miami Beach, but can also help the City meet mitigation requirements for unavoidable impacts.

The Muss Park seawall design was recently completed and permitted to protect an existing mature red mangrove and to plant new mangroves and other wetland vegetation near shore.

There are a number of living shoreline projects that are currently in design or construction, in increased order of progress, include the Maurice Gibb Park seawall project, the Brittany Bay Park seawall and living shoreline project, and the Indian Creek Flood Mitigation project. The Maurice Gibb Park seawall project provides an enhanced living shoreline where mature mangroves currently exist. Through the city’s partnership with The Nature Conservancy and support of NextEra Energy, $150K were granted to the city to build Brittany Bay Park project’s living shoreline and overlook, as well as renovate needed areas within the park. The project is anticipated to go for bid within the next months and begin construction early in 2021.

Construction of the Indian Creek Flood Mitigation project required unavoidable impacts to existing wetland vegetation, a portion of which is required to be mitigated on-site in accordance with the project’s Miami-Dade County Division of Environmental Resources Management (DERM) permit. The City is in the process of designing and permitting a living shoreline with mangroves and wetland vegetation waterward of the new seawall along Collins Avenue between 25^th Street and 26^th Street.

The following is presented to the members of the Land Use & Development Committee for discussion.