A fast-tracked plan to start armoring parts of Miami-Dade County around Biscayne Bay against powerful hurricane storm surge will soon be headed to Congress for authorization.
The $2.7 billion plan worked out between the U.S. Army Corps of Engineers and Miami-Dade County — and, now broken into phases — aims to create multiple lines of defense and tackles the easier work first. It also includes millions of dollars to study the effectiveness of reefs, mangroves and other nature-based solutions on shredding storm surge, which will help determine future features.
“We're trying to take bite-sized pieces,” said Col. Brian Hallberg, commander of the Corps’ Norfolk district overseeing the project. “We're going to solve a piece of the problem now in communities that really need some measures.”
The bulk of the work focuses on elevating 2,100 mostly residential structures, both single and multifamily in areas that planners identified as prone to storm surge flooding and financially vulnerable. About 400 structures, mostly government buildings, would be floodproofed with barriers. Those include police and fire stations, schools used as hurricane shelters, emergency operations centers and other facilities considered critical infrastructure. The costly elevation work is expected to cost nearly $700 million with flood-proofing costs estimated at $223 million.
(U.S. Army Corps Of Engineers)
A new plan for armoring Miami-Dade County from storm surge relies on a strategy of multiple lines of defense, starting with a hybrid reef to weaken powerful hurricane waves.
The revised strategy came after an initial Corps plan that relied heavily on engineered armoring, including towering flood walls and gates, drew criticism in 2018. The county rejected the plan and instead requested to submit a local alternative that provided more natural protection and didn’t wall off Miami from its treasured bay. The two groups also fast-tracked the work and set a year deadline.
“This is about how you can protect an urban community from storm surge. That wall of water that wiped out Fort Myers Beach is a hurricane vivid in our minds,” said Jim Murley, Miami-Dade County’s resilience chief. “We [had] to see if there's something that meets the requirements and we can live with it.”
Breaking the project into phases also eases the Corps’ workload in South Florida. The project is just one of several massive plans underway to better protect the region from flooding as climate change drives up sea levels and intensifies hurricanes.
In addition to the Back Bay plan, the Corps is in the midst of updating the sprawling Central & South Florida drainage system that stretches from north of Lake Okeechobee to the southern end of the state; a push to speed up Everglades restoration; and ongoing beach renourishment projects. That work comes with billion dollar price tags, with the C&SF expected to cost well over $2 billion and restoration work estimated at $23 billion. Multiple beach renourishment projects include work in Monroe, Miami-Dade, Broward and Palm Beach counties.
That work could also change how features are designed, Halberg said.
“It's not easy because you're going to make assumptions. And the assumption is, like the canal study. What does the future look like if that plan is approved,” he said. “When we do our feasibility study for the Miami-Dade Back Bay, we've got to make some assumptions.”
Determining what nature-based solutions work is also complicated. Once pilot projects are designed, they have to be modeled before engineering can happen, he said.
“Once we model it and we decide together with Miami-Dade County what that tentative selected plan looks like, then we’ve got to do the engineering behind it. And that's going to take years,” he said.
Landscape-scale projects can also be a moving target with climate change and continued development in South Florida.
The Corps launched an engineering with nature program in 2010 and has engineered work that incorporates nature across the country, from reef barriers off the Texas coast to dredging work in New Orleans. Nature-based solutions are being used to rebuild the Tyndall Air Force Base destroyed by Hurricane Michael. But the Miami work is intended to more precisely determine how much specific structures can counteract surge.
“We know there's value to nature-based solutions, right? It improves the water quality and helps with erosion control. But what we don't know is how does it help us in reducing damages,” he said. “Everybody wants nature based solutions. So it's like a playground here to test it and figure it out. And we’ll be able to apply what we learn here for the rest of the country.”
The draft plan can be viewed here. Public comment can either be emailed to the Corps at mdbb-csrmstudy@usace.army.mil or posted online here. A final report is scheduled to be released in June and scheduled to be approved by the Assistant Secretary of the Army in August. Officials then hope to have it authorized by Congress in the 2024 national water resources act now being hammered out in Washington.
This story was produced by WLRN, South Florida’s only public radio station at 91.3 FM, as part of a content sharing partnership with The Biscayne Times. Read more at WLRN.org.