Just days after the
collapse of the condo tower in Surfside, an obscure study
emerged that the building had been sinking into the earth
It remains unclear whether the settling, or subsidence, of Champlain Towers South was a factor when the 12-story building crumbled to the ground in the middle of the night on June 24, killing 98 residents. But the phenomenon of subsidence occurs throughout South Florida and has been implicated in damage to structures, especially houses, from Key West to Palm Beach.
A home at 222 West Kelly Park Road in Apopka is swallowed by a sinkhole on Sept. 19, 2017. The sinkhole is a result of Hurricane Irma. In South Florida, where sinkholes are rare and smaller than those to the north, subsidence is more gradual. When it takes place unevenly, with one side of a building settling faster than the other, it can crack floors, distort window frames and generate lawsuits over insurance coverage.
Subsidence has damaged the home of Surfside’s former mayor. In Parkland, about a dozen homes required foundation repairs from subsidence in the past three years. In Palm Beach Gardens, sinking earth cost Constance Bonvechio her house, cracking the ceiling and foundation, and leading to a lawsuit against her insurance company.
“If the decision [of the court] was a sinkhole, I was covered for it,” Bonvechio said, “But I was not covered for organic matter.”
The damage to
Bonvechio’s home wasn’t from a sinkhole. Bonvechio says
inspectors drilled for sinkholes at least five times. The
last time, “they went with an auger underneath the garage
where the main problem seemed to be.”
They found pine trees, she said. “There were pine trees decomposing under the house,” causing subsidence.
Bonvechio and her insurance company ultimately settled the case for an undisclosed amount in January 2013, court records show. Unable to afford the cost of repairs. Bonvechio sold the house for its land value.
The house of Daniel Deitch, former mayor of Surfside, is settling. The subsidence has led to an uneven door.
“What happens is the guys didn’t do the preparation of the soil by the compaction methods that can be used or they did it half-baked,” said Richard Slider, president of Slider Engineering Groups of West Palm Beach, who investigates the causes of building damage.
That leaves homes with concrete slab foundations placed directly on the soil vulnerable to incorrectly prepared land.
“As a result [of the subsidence], it causes this differential settlement,” Slider says, “and that’s what causes the problem. If the house is settling three-quarters of an inch on one side and a half-inch on the other, that’s a problem because the house wants to bend or break, and that’s what causes the cracks.”
In 1981, a sinkhole in Winter Park opened up gulping down 250,000 cubic yards of soil, five Porsches at a foreign car repair shop, the deep end of an Olympic-size swimming pool, chunks of two streets and a three-bedroom home. Picture taken May 11, 1981.
“This is normally due
to the ground under the slab drying and shrinking over
decades.” he said, adding that the houses typically settle
in only a ½- to 1-inch range. Engineers sometimes repair the
slab using pressure-injected foam that levels the
foundation, according to documents provided by Tracy.
But getting an insurance company to pay to fix the foundation is another matter entirely.
‘Cautious homeowners’ need multiple insurance plans
Florida’s homeowner insurance regulations often can leave people with a sinking feeling when they realize that uneven subsidence — and even full-on sinkholes — might not be covered.
Now, if you want to protect your home from subsidence you have to purchase extra insurance.
That’s because Florida law once required homeowners insurance to provide sinkhole coverage, but not coverage for subsidence. Today, it covers only “catastrophic ground cover collapse.”
By about 2010, sinkhole claims across Florida were rising. So in 2011, Florida’s Legislature altered the law to restrict payouts for sinkhole claims to only the most catastrophic cases. That meant that many people whose homes were merely damaged by subsidence in Southeast Florida were often not eligible for payouts.
Stephen Marino, managing partner of Ver Ploeg & Marino, a Miami law firm that represents insurance policy holders, said insurance companies have spent years carving out exceptions to homeowners coverage to reduce their costs. Now, if a homeowner wants coverage for a specific risk like a flood or a sinkhole, they have to buy it separately, he says.
PIC In 1981, a sinkhole in Winter Park opened up gulping down 250,000 cubic yards of soil, five Porsches at a foreign car repair shop, the deep end of an Olympic-size swimming pool, chunks of two streets and a three-bedroom home. Picture taken May 11, 1981. (Red Huber, Orlando Sentinel file)
“In Florida, to be a fully covered homeowner in certain parts of the state, you now have to have a property insurance policy for liability coverage, a windstorm policy, a flood policy and a sinkhole endorsement or separate sinkhole coverage,” he said. “Florida is treated differently than other states because a cautious homeowner has to buy four separate insurance policies for the same structure.”
Not a lot of people do, says Paul Handerhan, president of the Federal Association for Insurance Reform, a consumer-focused watchdog group.
“The broader coverage is more expensive, and I don’t believe many people purchase it,” he said.
One reason might be the high deductibles.
Friedlander, from the Insurance Information Institute, points out that optional sinkhole coverage has deductibles set by law at either “1%, 2%, 5% or 10% of the property dwelling limit. So, if your home’s dwelling limit is $300,000, and you have a 5% deductible, the deductible would be $15,000 before a claim payout is made by your insurer.”
In 2010, sinkhole damage claims in Southeast Florida almost doubled, data from the Florida Department of Insurance Regulation shows. Between 2006 and 2009, Miami-Dade and Broward accounted for only 2.9% of all sinkhole claims state-wide. In 2010, the two counties accounted for 4.2% of all claims statewide.
Hernando, Pasco, Hillsborough, and Pinellas counties, known as “the sinkhole belt,” accounted for well over 85% of all sinkhole claims in and payouts in the early 2000s.
The 2011 laws also had predictable effects. In one 2017 lawsuit out of West Kendall in Miami-Dade, a judge found in favor of an insurance company simply because the house in question had not collapsed — even though the insurance company recognized that the “cause of distress to the property is related to non-engineered fill causing settlement of the soils which caused damage to the home,” court records read.
But not all sinkhole claims go unpaid.
“I myself have 30, 40 claims in the Hollywood area, in the Plantation area, South Miami area, where the engineers for the insurance companies have confirmed sinkhole activity,” says Howard Levine, an attorney who has represented Broward homeowners in sinkhole cases against insurance companies.
Rarer in larger buildings, but possibly more dangerous.
Subsidence has affected at least one other large building in the area. In downtown Miami, the opening of the 47-story building now called Miami Tower was delayed in 1988 after the building sank 5 inches on one side, disrupting the operation of its elevators. Engineers had to remove and reinstall the elevators after the building finished settling into its foundation.
In Surfside, the Champlain Towers building sank at a rate of about 2 millimeters a year in the 1990s, according to a study by Florida International University professor Shimon Wdowinski.
“Two millimeters per year is usually not a big threat,” Wdowinski said, unless the building was subsiding unevenly, though the data from his study cannot speak to that.
Wdowinski used satellite data to determine that the building itself was sinking. He also detected small pockets of land subsidence that were distributed along the western area of Miami Beach, a part of the city that was historically built on fill dredged from the bottom of Biscayne Bay.
But it appears that the Surfside building may have lacked design elements intended to prevent it from settling unevenly, say two independent civil engineering experts who reviewed the building’s plans.
Like most large structures in Florida, Champlain Towers South was built on piles — long concrete rods sunk or pounded deep into the earth that hold the building up in soft or mushy soil.
Atorod Azizinamini, dean of the Department of Civil and Environmental Engineering at Florida International University, says that the plans for the Surfside building lacked any indication that its support pilings were connected by grade beams, which can tie them together and prevent them from settling at different rates.
Mohamed W. Fahmy, a lecturer in engineering at the University of Miami who also runs a structural consulting firm, concurs with Azizinamini’s analysis about the building’s vulnerability to lateral movement caused by differential subsidence.
He points out that the building’s foundation — an almost foot-thick slab of concrete laid around all the piles — does not have rebar connecting it to the piles at both its top and bottom.
Both Fahmy and Azizinamini said that the design elements lacking from the building don’t prove that uneven settlement actually took place, just that the building lacked an element designed to prevent it.
“You’re going to find out many factors played a role in this thing,” Azizinamini said. “Not just one.”
Allyn Kilsheimer, the engineer hired by the Town of Surfside to investigate the collapse, is skeptical of theories that the building was vulnerable to differential subsidence.
“We’ve done close to a thousand buildings that we have on piles. We don’t have grade beams in any of those,” he said.