What are the basic facts about sinkholes?

Wednesday, March 27, 2019

Sinkholes occur naturally throughout central and north Florida, where a limestone layer underlies the soil and can be easily dissolved by water. They can be the kind that swallow up houses and cars, or smaller “chimney” sinkholes like the one shown at right.

    Although newly formed sinkholes are a problem, especially when they occur under a home, old sinkholes that existed before land development and construction are protected by law from disturbance or filling. A vegetative buffer is required around a sinkhole site to preserve its natural condition and protect its connection to the drinking water in the aquifer below.

    Warning signs of a developing sinkhole include:

  • Structural problems in a home, including development of cracks in walls and floors, doors that won’t close properly, and sinking pavement outside.
  • Tilting posts or fencing in yard. 
  • Sediment or cloudiness in well water.
  • Depressions in yard that collect rainfall and were not there previously.
  • Sinkholes are most common under sandy soils, where the soil layer is less than 25 feet thick above the limestone. They are less common where there is a think layer of clay soil.
  • Although sinkholes are dramatic and feared soil subsidence (sinking) events, decay of tree stumps and roots, burial of tree debris during land development, leaking water pipes, cracked and leaking swimming pool, and heavy stormwater runoff from roofs and large paved areas can also cause soil subsidence.    Evidence of sinkhole formation should be taken seriously, since it can become a life-threatening situation. Only a licensed engineer or geologist is qualified evaluate any sinkhole that opens up, and a licensed sinkhole repair contractor should be used to mitigate it. 

    Also, see our blog posts How can homebuyers protect themselves against buying a house over a sinkhole? and What is a chimney sinkhole?

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

Here’s links to a collection of our other blog posts about SINKHOLES:

Why do so many more sinkholes open up after a hurricane?

What are the warning signs of a sinkhole? 

What causes sinkholes?

What is my chance of buying a Florida home over a sinkhole? 

• How does a repaired sink hole under a house affect its market value?

• Where are sinkholes most likely to occur in Florida? 

• Are sinkholes happening more often?

   Visit our SINKHOLES page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

Photo - Southwest Florida Water Management District

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