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Waterfront AccessFeatured StoryWEDG

WEDG Insights: Implementing Living Shorelines in Miami

Over the course of the next few months, Waterfront Alliance will be sharing WEDG Insights, as a part of the WEDG Professionals platform, toexplore the techniques, policies, projects, and professionals who are driving the movement towards excellence in resilient, sustainable, and accessible waterfront design.

 Patrick Shearer, P.E., WEDG is a civil engineer with a degree in natural resources and environmental science concentrating on water resources, ecological restoration, and coastal resiliency. Mr. Shearer has over 13 years of coastal experience and 6 years with E Sciences, Inc. in its Miami office.  Patrick has planned, designed, and implemented many types of urban stormwater retrofits, living shorelines, coastal resiliency, water quality, and green infrastructure projects utilizing watershed-based approaches in the Chesapeake Bay, Indian River Lagoon, Tampa Bay, and Biscayne Bay watersheds. Patrick is currently involved with innovative urban retrofit projects such as the Adaptive Redesign for Jose Marti Park along Miami River and the Wynwood NW 3rd Avenue Woonerf in the art district.  Mr. Shearer regularly serves as the Engineer of Record for designs incorporating innovative stormwater retrofits, green infrastructure such as permeable pavements, urban forestry retrofits, bioretention, nutrient treatment, and stormwater re-use systems to increase resiliency and sustainability and pushing innovation using materials, construction techniques, creativity and knowledge to overcome today’s urban design challenges. 

Waterfront design is about managing tradeoffs: identifying opportunities, managing physical constraints, and satisfying stakeholders for the greater common good.  Miami’s waterfront, with its medium to high wave energy from wind and seasonal storms, robust redevelopment activity, and active waterways, has unique design opportunities and constraints—especially when it comes to living or naturalized shorelines. In light of recent storms and climate change, many people envision living shorelines as a major part of future-focused designs. Traditionally, living shorelines require more land to accommodate built and natural elements; however, new technologies, as we are piloting at Jose Marti Park along the Miami River, have the potential to manage tradeoffs for waterfront design and meet the needs of all stakeholders. WEDG® (Waterfront Edge Design Guidelines) can be used to show stakeholders how these new technologies can provide better service to Miami’s waterfront compared to traditional seawalls.

Historically, the edge of Biscayne Bay and the Miami River were dominated by mangroves, whose prop roots protected the land from erosion, provided habitat, and filtered water. The Miami Circle—the 2,000-year-old Tequesta’ tribal site at the mouth of the Miami River—is an acknowledgement to the cultural ties and balance with the natural water cycle. It is believed to have contained a wood-structure on stilts set in native limestone post-holes, which were aptly built above tidal flood elevations. This same porous oolitic limestone which supported the ancient structure today forms the foundation for many high-rise buildings. Highlighting how these historical elements shape the physical and sociological aspects of Miami’s waterfronts is a key part of WEDG.

Today, Miami’s waterfront is dominated by concrete seawalls, many of which were built too low, are in disrepair, or are failing due to crumbling concrete or corrosion of steel rebar within the concrete. Some seawalls have collapsed, risking parking lots and other infrastructure. These existing seawalls do not provide adequate water quality protection to meet the ecological goals of Biscayne Bay’s stakeholders and its protected Outstanding Florida Water designation.

With six feet or more of sea level rise projected by 2100, Miami is undergoing a massive public-private effort to reimagine its shoreline infrastructure. There is broad public consensus that a design renaissance is needed to preserve and adapt our local culture, real-estate values, and ecology of our waterways. Living shorelines are an increasingly popular call to action for addressing sea level rise when presented with options at public meetings.

That said, traditional living shorelines (i.e., wetland restoration) are challenging for Miami’s waterways due to wave energy, water depths for boat access, erosion control, sight vistas, flood considerations, and permitting constraints. New design criteria require shorelines to be protected to elevation 6.0 feet NAVD88 (North American Vertical Datum) and a future adaption height of 8.0 feet NAVD88. In many places this means a waterfront edge upgrade of up to six feet vertically just to meet the new standard. Filling waterward into the bay or river to construct a typical living shoreline is not easily permitted, and in many places not allowed, for accommodations such as wide living shorelines due to existing regulations protecting seagrass, corals, mangroves, and manatees.

 

Riverwalk shows standing water from King Tide Event. Boats can be passing by the site on the Miami River. Photo taken by Patrick Shearer, Senior Engineer at E Sciences, during September 30, 2019.

 

As WEDG helps designers discover, Miami still has opportunities to make shoreline edges greener and more resilient despite these constraints. Advances in materials and construction technologies which allow for hybrid type “living seawalls” that are better suited for Miami’s high-energy shoreline environment than traditional living shorelines.  Living seawalls allow a combination of hard infrastructure with nature-based technology to allow designers to adapt to the harsh urban coastal conditions in Miami and pursue the triple-bottom line of equity, economy, and ecology.  Ecological concrete can be used to build bio-armor over time, filter water, provide habitat for native ecosystems, and reduce carbon footprint – a key goal for the City as we reenter the Paris Agreement.  Non-metallic rebar has been pioneered locally by University of Miami engineers and affords the ability to side-step the corrosion limitations of steel-based rebar and this new breed of rebar can be utilized to produce seawalls with lifespans of 75+ years, typically considerably greater than today’s seawalls lifespans.  Additionally, non-metallic rebar allows for use of an innovative formulation of concrete batched from seawater and recycled concrete aggregate, allowing further reduction of carbon footprint and resiliency advantages.  Ecological concrete textured to resemble mangrove roots can further create the 3D habitat necessary for native species, improve water quality, and reduce wave energy, thus promoting resiliency.  These technologies allow the opportunity to be combined for complementary strengths to achieve more advanced resilient shoreline designs.  Additionally, narrow riprap benches, or breakwaters, can be planted with mangroves as a “living sill” to further enhance shoreline geometry, dissipate wave energy, and provide essential habitat.  This type of approach can complement a living seawall in a manner that is more practicable to permit and implement.

The cost-benefits of living seawalls compared to traditional seawalls are best realized when a life-cycle comparison is made. The living seawall can greatly outperform today’s antiquated concrete seawall designs—especially when comparing WEDG credits.  The living seawall outcompetes traditional concrete seawalls when comparing lifespan, permitting timeline, resiliency, water quality filtration, ecological habitat, benthic community recruitment, biomimicry, carbon footprint reduction, habitat mitigation/creation, nutrient reduction, wave attenuation, and maintenance. Maintenance costs for traditional concrete seawalls can include the “hidden” cost of full seawall replacement when the wall reaches disrepair, sometimes in as little as 20 to 30 years. Ecological living seawalls grow stronger over time, as bio-armor creates a hardened exterior which is further concreted by living organisms which help to strengthen the structure, while also providing water quality filtration and habitat.  When comparing an entire community of living seawalls or concrete seawalls, there is a vast impact on the ecological considerations and array of benefits that go beyond property protection and extend to neighborhood placemaking and eco-tourism, both increasing real-estate values and tax bases locally.

 

Mr. Shearer stands next to a grated inlet within Jose Marti Park Riverwalk which can be seen fully submerged due to a King Tide Event.

 

WEDG projects can identify and reduce the vulnerability to these every-day and sea level rise impacts by better design, and to supplement local building codes to promote these design guidelines instead of requiring – which can lead to better adoption.  As an engineer working in this field, I think WEDG will provide the structure and guidance needed to enact change in our policies, motivate urban design practitioners to innovate, drive more robust building codes better suited for climate adaptive development and to build more resilient coastal communities.

 

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Project Team:

Jose Marti Park Adaptive Redesign, City of Miami Forever Bond Project

 

ESciences, Inc: Civil and Stormwater Engineering, Tree/Bat Survey

CUMMINS │ CEDERBERG: Coastal & Marine Engineering, Benthic Survey, Environmental Permitting

Lead by CURTIS+ROGERS DESIGN STUDIO: Master Planning, Adaptive Redesign, and Landscape Architecture

 

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Image Credits:

Photo 1: Photo taken by Jennifer Artiles, Staff Engineer at E Sciences, during September 10, 2020.

Photo 2: Photo taken by Patrick Shearer, Senior Engineer at E Sciences, during September 30, 2019.

Photo 3: Photo taken by Jennifer Artiles, Staff Engineer at E Sciences, during September 23, 2020.

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