Florida sinkhole: Massive hole between two homes is plugged

Two homeowners in the Villages, a sprawling retirement community in Florida's Sumter, Lake, and Marion counties, are now breathing a sigh of relief.

A massive 50-foot wide by 60-foot deep sinkhole had opened up between two homes. The hole extended under one driveway and had gobbled up a chunk of the front yard. 

One of the homeowners had hired Helicon Property Restorations to stabilize and fill a smaller sinkhole two weeks ago, and the crew had almost completed the work. But it rained Friday night and a much larger sinkhole appeared overnight and continued to expand.

Workers spent Saturday dumping 15 truckloads of grout into the hole and "hadn't put a dent in it," Battalion Chief Pete Carpenter of The Villages Fire Rescue told the Sun Sentinel.

"It's just continuing to grow," he said.

But by Sunday, workers had successfully filled the hole with 40 truckloads of sand and cement and were expected to finish the landscaping work on Monday.

Sinkholes are common in Florida. They're so common that the state has county-by-county maps detailing their locations. The 2008 Sumter County map, where The Villages sinkhole appeared, includes at least five sinkholes more that 200 feet in diameter.

What's the geology behind Florida sinkholes? Last year, The Christian Science Monitor's Liz Fuller-Wright wrote about them after a sinkhole opened up near Disney World.

Sinkholes start with water and limestone, two things Florida has in abundance. Limestone dissolves in water, and the more acidic the water, the faster the limestone gets eaten away. What starts as a small hole, deep underground, can grow bigger and bigger until it's a cave you could walk upright in. Flowing ground water keeps dissolving away the top, sides, and bottom of a limestone cave, enlarging it in all directions. For people living on the surface above these caverns, there's no obvious sign that the ground beneath their feet is being eaten away from below....

Just because the state of Florida is almost entirely built on limestone, it doesn't mean that all Floridians are at equal risk of sinkholes. The northern part of the state typically has hundreds of feet of sand on top of the limestone, while much of southern Florida has a thick layer of clay protecting the surface, says  Boo Hyun Nam, an engineer at the University of Central Florida. Central Florida, however, has only thin layers of sand (to the east) or clay (to the west).

In fact, three central Florida counties to the west of Walt Disney World – Hernando, Pasco, and Hillsborough – have been dubbed "sinkhole alley," and are responsible for more than two-thirds of the state's sinkhole damage claims between 2006 and 2010.