Real Estate Marketing & Beyond
The idea of your home disappearing into a sinkhole is something that seems utterly horrifying, and the recent increase in this kind of event has the experts scratching their heads.
photo credit: horslips5 via photopin cc
The problem is discussed in an article by CNBC, and scientists think it may at least partially be due to the fact that developers for extracting more water from the ground in order to develop land, or is down to water being pumped out for agricultural use. Apparently large areas of Florida are situated on limestone, and the stone can be dissolved by the natural acidity of water. However its presence also acts as a support. If it's removed then support is lost, and the problem can be exacerbated by heavy rains.
According to the experts in Florida real estate, the amount of development means builders are being forced to search for land further outside the cities. As a result homes may end up being built on sites that are less than ideal as developers struggle to meet the demand for competitively priced properties. This could make the sinkhole problem even worse in the future. It's very difficult for builders to know whether or not a sinkhole is likely to occur on a site, and even though they have to do some drilling in order to meet building codes this doesn't tell them whether or not a sinkhole will develop in the near future.
Insurance companies in Florida are required to cover homeowners against catastrophic ground collapse, and in recent years the number of insurance claims for damaged caused by sinkholes has increased significantly. In fact claims have increased so much that there are concerns that they could threaten the property insurance market in Florida. The costs for ensuring a home against sinkhole damage can vary dramatically depending on the location of the property. If the home is in an area that isn't considered to be particularly high risk then insurance can cost around $200, but this can easily increase to $2,000 for homes in higher risk areas.
Approximately a third of all sinkhole activity recorded in the last 50 years has occurred in the previous 13 years, and half of all that activity took place during the last three years. Not surprisingly, sinkhole remediation companies have seen an increase in business over the last five years, and point out the increase in activity could be down to a number of factors, and this is why it's so important to get an engineer to assess the area.
Re the issue of sinkholes, I believe the issue is loss of groundwater. Reduced flow of most of Florida's major springs - Silver, Rainbow, etc - is a surface expression of these losses. As people sink more and more straws in the form of wells into the shallow zones of the Floridan Aquifer, the hydraulic pressure of aquifer water is drained from the natural cavities of the underlying limestone aquifer formations. When developers come along and add tons of weight in the form of streets, curb and gutter and homes on top of the ground, the concentrated pressure from above simply collapses the limestone cap over the aquifer chamber.
This probably is too simplistic an explanation and certainly cannot explain all sinkhole formations, but I bet it's a factor in a number of cases.
What is needed, I believe, is a really comprehensive geotechnical survey - equivalent to a metes and bounds surface land survey - of all building sites in the regions where the Floridan Aquifer outcrops or lies close to the surface - and certainly in all aquifer recharge areas where a minimum of overburden materials may serve to buffer the development impact.
The result might well prohibit surface development in certain fragile areas where it is certain development investments would be lost, or enormously compromised by corrective remedies. But it would seem to me that would be preferable to losing those investments and conducive, perhaps, to protecting aquifer zones which certainly are lost or diminished by remedial activities.
Just a thought.
Allan Horton
Sarasota