The catastrophes caused by sinkholes have been in the news a lot lately. Here is an example that includes an entire gallery of sinkhole photos: http://www.huffingtonpost.com/2013/03/25/new-sinkhole-seffner-florida-video_n_2948846.html#slide=275941
If the ground that is built upon is unstable, porous, or above known caverns then the structure is susceptible to foundation problems, including something as devastating as a sinkhole. Some properties are built on slopes, landfill, or floodplains and are at risk of becoming unstable. How does a building owner avoid this problem? The answer is to hire a Soils or Geotechnical Engineer. These professionals evaluate the ground underneath the property and can provide recommendations about how to mitigate the conditions in order to build more safely. In some cases, they may recommend that the site is unsuitable for building. If so, the wise course of action is to choose another site.
Geotechnical Engineers are not the only engineers necessary for a project that is built in an area with known stability concerns. Structural Engineers provide the calculations necessary to create a building that can withstand natural forces such as earthquakes, slippage, and liquefaction to the extent that the problem can be foreseen. Obviously, some natural forces are unforeseen and cannot really be alleviated in advance.
My home is built on what is known as “adobe” or clay and the ground is hard and solid, but if enough wetness penetrates it then the ground expands. This can cause quite a bit of earth movement, and cracks in the interior drywall or in the exterior stucco are common in the neighborhood. Extra foundation work was required to allow the building to adjust to the seasonal expansion and contraction of the soil.
If you live in, or are building in, an area with ground stability concerns, please do not be penny-wise and pound-foolish. Hire a good geotechnical engineer to give you a report on the soil condition and also hire a good structural engineer to assist in the design process.
Lorianna Kastrop The Kastrop Group, Inc. Architects