NSN has assisted over 600 home owners, of previously denied insurance claims, acquire sinkhole coverage in the past ten years. We have developed a sound hydrogeologic testing protocol for mapping the subsurface geology and locating sinkhole features. We have performed sinkhole investigations for condominium complexes in Florida and Tennessee. We have mapped sinkhole features associated with highway road collapse in Florida and Maryland. A growing part of our business is the pre-construction mapping of sinkhole features for commercial and industrial clients. We have successfully utilized MER to map building sites for assisting foundation design in sinkhole environments, and assisted land developers in determining which properties to build on and which should be left as nature preserves. The use of our Multi-electrode Electrical Resistivity (MER) survey equipment permits us to rapidly map an entire site in one or two days. Our results are equivalent to the drilling of several hundred test holes that would take months to complete.
Winter Park, FL Sinkhole
Sinkhole Animation
A more common type, but less well known to the public is the cover subsidence sinkhole. These sinkholes are very slow moving. They may be small, or quite large in their aerial extent. Whereas the cavern collapse sinkhole leaves no question as to what the operation earth movement is, the cover subsidence sinkhole is often mistaken for other land subsidence factors such as compression and decomposition of organic sediments, shrink/swell clay, differential settlement or soil slump or creep. NSN has developed testing methodologies specifically designed to recognize the presence of cover subsidence sinkholes. The most common sign of this type of sinkhole is cracks on the interior or exterior of a building or house.
The following diagrams are examples of how NSN investigates and interprets sinkhole data:
Click on diagrams below to enlarge.
