Sinkholes are a common feature of Montgomery County and the surrounding areas. The following diagrams illustrate the most common sinkhole formation mechanisms for this area.
Sinkholes are the result of water movement through limestone rock formations. As water moves through the natural cracks in these formations, the limestone is slowly dissolved leaving open spaces in the rock structure. When enough limestone has dissolved to weaken the rock, the surface soil collapses into a cone shaped depression commonly called a sinkhole. The size of the sinkhole is dependent on several factors including groundwater level, surface water infiltration rate, overburden depth, and water chemistry (acidity). Once formed, a sinkhole can grow in size unpredictably, based on conditions specific to that area.
Sinkholes are difficult to stabilize permanently because they are chronic features that may grow or reform after filling. The process of filling sinkholes may also cause changes in the existing patterns of surface runoff and ground water flow that should be avoided. It is important that a licensed engineering or geotechnical professional be consulted before making any attempt to alter or "fix" a sinkhole.
In areas zoned for residential use, Montgomery County Storm Water Regulations require a 50 foot undisturbed buffer zone of deep rooted vegetation to help protect ground water quality. The buffer provides significant reduction of total suspended solids, nutrients, and other pollutants being transported into the sinkhole by storm water flows. The water quality buffer also acts to limit activities that might inadvertently increase a sinkhole's instability. This is necessary because the limestone underlying a sinkhole may be unstable, and vibration from construction activity and heavy equipment can result in increased personal and property danger.
Because sinkholes represent a direct path for pollution to enter area water resources, it is illegal to put any substance on the ground that can be washed into any sinkhole, or to dispose of trash, dirt, yard waste, garbage, building materials, animal wastes or chemicals by dumping them in or around a sinkhole. Landowners, farmers, businesses and industries are legally liable for accidental leaks that may result in contamination entering a sinkhole.
Care must be taken to prevent pollution from entering sinkholes. By taking a few basic precautions around sinkholes, you can help prevent water pollution. These precautions include:
· Establish a buffer zone of undisturbed, deep rooted, native vegetation around the sinkhole, which will act as a pollution filter. While the EPA recommends a 100 foot buffer, studies have shown that even 50 feet of vegetated buffer will significantly reduce the pollution that can be carried into a sinkhole by storm water runoff.
· Use fencing to keep livestock from the immediate vicinity of the sinkhole. This will limit the deposition of animal wastes near the sinkhole, which could be carried into the sinkhole and on to our streams by storm water runoff.
· Do not use fertilizers, pesticides or herbicides around sinkholes.
• Do not dispose of trash, dirt, yard wastes, garbage, building materials, animal wastes or chemicals by dumping them in or around a sinkhole.
For more information, please go to:
EPA's Office of Ground Water and Drinking Water Web Site
Tennessee Department of Environment and Conservation, Office of Water Pollution Control Web Site
Montgomery County Storm Water Management and Control Regulation Program Web Site
Also APSU has a great brochure with information on sinkholes
A word to For Sale By Owner's: I would suggest if you have any questions about your property, to get everything documented and in place before you try to sale on your own. You won't be having anyone representing you, because you are doing it on your own. You will be dealing with either a buyer who isn't represented or a buyer who is. It can get pretty stressful if you don't have everything checked out and in place. It can also come back to haunt you even after the closing, if those important features or defects were not disclosed.