Sinkhole Investigation

Sinkhole investigations are complex and may be subject to the interpretation of the project engineer.
When having property examined for causes of settlement, it is important that the engineer have experience both in locating and repairing sinkhole damage. Oftentimes, engineers will spend a majority of their time performing investigations and spend little time in actually repairing sinkhole damage. The result is an engineer who is prone to "false positives," providing the property owner with an inaccurate or incomplete solution. The property owner then finds themselves with a property subject to severe devaluation because it has now been tagged as a "sinkhole property," merely because the engineer wanted to offer a simple solution and provide services for litigation over the matter. As additional protection against this problem, make sure the engineer's investigation is complete and does not rely too heavily upon one testing method

Damages caused by sinkhole activity are routinely repaired by using modern, geotechnical engineering methods.

While these repairs may be costly, they are usually covered by insurance. Before attempting to hire any engineer to evaluate and/or repair your property, make sure the solution has been approved by a licensed, professional geologist. The decision on whether a particular property can be repaired depends on the nature and extent of the activity. A decision as to whether an attempt should be made to repair sinkhole damage should be made after consultation between the property owner, the insurance company, and the engineering company.

With any kind of professional service, it is important that you receive competent, comprehensive advice. If your engineer does not provide you with comprehensive information about the settlement problem, you will not be able to determine a complete and accurate solution.

There are specific licensed engineering companies that specialize in performing geotechnical investigations into what may be causing settlement damage. Because Florida requires property insurers to provide insurance coverage for sinkhole damage, there are a multitude of different geotechnical engineering firms that specialize in these investigations. However, there is no standard form procedure for evaluating the existence of sinkhole activity and many investigators fail to perform a complete analysis, resulting in incomplete conclusions for the insurance company and the property owner.

Although there are several sophisticated procedures available to engineers in evaluating the presence of sinkhole activity, the information gathered is only as accurate as the skill set of the engineer performing the test. A thorough and accurate investigation into whether sinkhole activity is present should include the following:

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• Site Investigation - A licensed professional engineer should evaluate the area in which the target property is located. Historical maps provide important information about the possible causes of settlement. Areas where mining has taken place nearby, for example, may suggest that reclaimed soils were deposited at the property location.
• Use of Geophysics Engineers will utilize several different forms of geophysical testing methods, enabling them to identify areas where inconsistent soil conditions are present, areas better known as "anomalies." These geophysical methods include procedures such as ground penetrating radar or another device that tests the soils electrical resistivity. These procedures, while increasing in complexity, are usually are just a first step as most engineers will not base their conclusions on them alone, preferring instead to use other tests in tandem.
• Site Drilling There are a variety of drilling techniques available. These include shallow drilling, often called "hand auger" drilling, which removes samples of soil to depths of around 7 feet. This kind of drilling alone, while it can provide valuable information, is usually incomplete because it does not penetrate to a sufficient depth. Sinkhole activity may occur much deeper and may not be observable at these shallow depths. The most reliable form of drilling includes standard penetration testing ("SPT" drilling), which is a form of drilling that reaches depths much deeper depths of 75 to 100 feet.
• Laboratory Analysis Once soil samples are removed by either hand augers or SPT, these samples should be analyzed for different characteristics. Studies may be necessary to determine whether the organic content is too high or whether clays found at the site are too expansive.
  

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