Today's Opinions, Tomorrow's Reality
By David G. Young
Wilmington, Delaware, June 29, 2021 --
Florida's waterfront towers are at as much risk from a loss of faith as they are from rising tides.
A forest of concrete towers rises at Florida’s Atlantic shoreline beginning at Key Biscayne just south of Miami Beach. The towers continue in an almost unbroken line past Palm Beach over 70 miles to the north. More tower communities periodically dot the coast for the next 200 miles all the way to the northern city of Jacksonville.
The collapse of Champlain Towers South just north of Miami Beach shows the vulnerability of these developments that are the linchpin of Florida’s coastal real estate market. Starting with a few towers in Miami And Palm Beaches the 1920s, tower development exploded after the Second World War and has continued unabated ever since.
The oldest towers, built on high ground, are now a century old. Many of their more recent companions were built on landfill atop coastal marshes. These buildings are most vulnerable to saltwater intrusion that will inevitably corrode the support columns of the towers if left to nature’s wrath. Without expensive retrofitting that may rival the value of the towers, collapse is ultimately inevitable.
Reports from at least two maintenance workers1,2 point to standing salt water inundating the lowest garage levels of The Champlain Towers South, something that was allegedly going on for years with only cosmetic concrete patchwork as mitigation. If proven true, this suggest that the building suffered from foundation design flaws, improper concrete support construction, and a building management that turned a blind eye to urgent repairs. All three factors caused the building’s collapse. The doomed tower’s deterioration, in short, is probably not representative of of the thousands of other towers that line the coast.
But that is where the good news ends. The same natural forces that deteriorated the concrete supports of the doomed building threaten every single tower on Florida’s coast. Salt water permeates the porous limestone of South Florida under the foundation for all waterfront towers. Engineers have long know that chlorine ions slowly permeate concrete and corrode the iron rebar that adds strength to columns. Bridges with supports in salt water must be constructed with special less-permeable concrete mixes that are less permeable and steel reinforcing must be specially protected from exposure. But even if all known measures are taken, it will only delay the inevitable deterioration of the supports. Salt water will ultimately win.
This dark picture is true even with existing sea levels. Environmental alarmists who claim that climate change and sea level rise significantly contributed to the collapse of Champlain Tower are either dishonest or uninformed. While Florida’s sea levels have risen only six inches since the mid-1990s3, a minor change compared to the natural tidal variations that allegedly flooded the parking garage on a regular basis.
But while sea level rise did not cause this collapse, it most certainly will cause collapses in the future. Projections are that sea level will between one and eight feet by 2100.4 That’s an awful lot of seawater corroding the basements of thousands of concrete towers along the coast.
To be clear, this is a long-term threat that will take decades to affect most towers. But the value of real estate is not solely based on the structural soundness of most towers — it is based on human perceptions of what is safe, desirable and fashionable. Already, fears of similar collapses are spreading along the Florida cost like wildfire. There is a real risk that these fears will lead to a loss of faith in waterfront towers as investments. Such a loss of faith, if it materializes, could erode the foundation of Florida's real estate market faster than salt water ever could.
Related Web Columns:
Paradise Lost, November 2, 2020
4. NOAA, Climate Change: Global Sea Level, January 25, 2021