President's Message – Sinkholes "101"
Recent events have put sinkholes and the dangers they pose to the public back in the forefront of most people's minds. National media as well as local media have all been covering "sinkholes" and the psychological as well as the physical damage they cause the public. When talking about sinkholes, sinkhole activity and sinkhole claims, specific terms and references are made by engineers, geologists, contractors and adjusters.
This message is an attempt to enlighten the General Public about those terms and regulations and how they may affect your claim. It is titled "Sinkholes – 101" and is intended to be the starting guide for an understanding of what all the technical references mean and how they may relate to you and your claim.
Terms that are frequently used in talking and/or reporting about sinkholes and the insurance coverages that address them are as follows:
Sinkhole – a landform consisting of a depression or hole at the ground surface formed by the end result of sinkhole activity. Typically, sinkholes form from the movement (raveling) of soil downward into cavities or caverns located in the underlying limestone that is the bedrock formation for Florida and several other states. Limestone is the most soluble of the common rock types that form the bedrock layer underlying the United States. The three major types of rock are igneous, sedimentary and metamorphic, with limestone being a sedimentary rock and the most soluble by mildly acidic groundwater.
Sinkholes can be as large as several hundred feet in diameter or as small as a few feet wide when they first form. Their depths can also vary by the same amounts. The initial size and depth of a sinkhole is a function of the composition of the soils above the limestone, how far below the surface the limestone begins, how much soil has raveled into the rock and how large is the cavity, void or crevice that accepting the raveling soils. After initial formation sinkholes can "grow" due to continued soil migration into the cavities or from caving due to a function of slope stability along the exposed sides of the hole.
Statute language defines a sinkhole as ……. "Sinkhole" means a landform created by subsidence of soils, sediment, or rock as underlying strata are dissolved by groundwater. A sinkhole forms by movement or collapse of soils into subterranean voids created by the dissolution of limestone or dolostone or by subsidence as these strata are dissolved.
Sinkhole Activity – the geologic process that causes sinkholes to form. This process can be slow or rapid in its progression of moving soil into cavities already existing in the limestone through solution channels or crevices located in the surface of the limestone leading to the cavities. The process works in a bottom to top direction starting at the surface of the limestone and working its way upward through the overburden soils. Sinkhole activity is driven by either groundwater saturating the soils above the rock changing from being in a static condition to being in a dynamic condition. This is similar to a bath tub full of the water having the drain plug pulled. When the plug is pulled groundwater moves downward into the rock and transports soil along with it through a breach in the confining layer of low permeability clayey soils separating the sands from the porous limestone. As this soil movement continues a soil void or reduction in soil density develops along the rock surface and with time, may progress upward getting larger and/or weaker. When the overburden soils can no longer bridge or span over the developing soil void, the soils sag forming a depression or even a collapse resulting in a sinkhole at the land surface. The sagging is called a "Cover Subsidence Sinkhole" while the collapse is called a "Cover Collapse Sinkhole". The latter is the type of sinkhole that affected the Seffner property in March of this year and the Orlando property most recently in August. The warning time prior to the collapse can be very short as in the Seffner event or slightly more prolonged as in the Orlando event.
Florida Statutes define sinkhole activity as ……. "Sinkhole activity" means settlement or systematic weakening of the earth supporting the covered building only if the settlement or systematic weakening results from contemporaneous movement or raveling of soils, sediments, or rock materials into subterranean voids created by the effect of water on a limestone or similar rock formation.
Sinkhole Loss – typically insurance policies have language that reflects coverage when a "sinkhole loss" occurs. However, a "sinkhole loss" can be as complex as having to meet a specific definition given to "catastrophic collapse" which may require unrepairable damage to have already occurred in conjunction with a landform "sinkhole" to be present before coverage takes effect; or, a "sinkhole loss" may be as simple as physical damage to the covered structure or building caused by "sinkhole activity" regardless as to level of damage which has occurred at the time of the investigation. The latter or simple policy definition for a sinkhole loss is one of dwindling numbers that generally is found in policies dating prior to May of 2011.
By new statute language (post May 2011) the definition of a "Sinkhole loss" is "structural damage" to the covered building, including the foundation, caused by sinkhole activity. Contents coverage and additional living expenses apply only if there is "structural damage" to the covered building caused by sinkhole activity."
It is also important to understand what is meant by the "covered building". The term "covered building" is generally synonymous with "principal building" and has been left to the individual insurance carrier to define. It generally includes the main living area of the structure only with any and all appurtenances such as pool decks, in-ground pools, patios, and/or detached structures excluded from the definition.
Knowing which coverage you have is very important in determining if and how your home will be covered by your homeowner's insurance in the event that damage begins to occur. Knowing which type of coverage you have is also important in determining if a Professional Engineer or Professional Geologist can investigate your concerns and determine if sinkhole activity is present beneath your property and it can be determined to be a cause of damage within a reasonable professional probability before the damage becomes too significant to repair or before the potential of imminent collapse occurs.
The post May 2011 Florida Statute §627.706 defines “structural damage” to mean a covered building, regardless of the date of its construction that has experienced the following:
1. Interior floor displacement or deflection in excess of acceptable variances as defined in ACI 117-90 or the Florida Building Code, which results in settlement related damage to the interior such that the interior building structure or members become unfit for service or represents a safety hazard as defined within the Florida Building Code;
2. Foundation displacement or deflection in excess of acceptable variances as defined in ACI 318-95 or the Florida Building Code, which results in settlement related damage to the primary structural members or primary structural systems that prevents those members or systems from supporting the loads and forces they were designed to support to the extent that stresses in those primary structural members or primary structural systems exceeds one and one-third the nominal strength allowed under the Florida Building Code for new buildings of similar structure, purpose, or location;
3. Damage that results in listing, leaning, or buckling of the exterior load bearing walls or other vertical primary structural members to such an extent that a plumb line passing through the center of gravity does not fall inside the middle one-third of the base as defined within the Florida Building Code;
4. Damage that results in the building, or any portion of the building containing primary structural members or primary structural systems, being significantly likely to imminently collapse because of the movement or instability of the ground within the influence zone of the supporting ground within the sheer plane necessary for the purpose of supporting such building as defined within the Florida Building Code; or
5. Damage occurring on or after October 15th, 2005, that qualifies as “Substantial Structural Damage” as defined in the Florida Building Code.
When one or more of the above five items has been met then a comprehensive sinkhole investigation is required to be conducted. Generally, it will require a comprehensive sinkhole investigation to determine if sinkhole activity exists within the subsurface soils unless it already has progressed near to the surface. In rare instances, the finding of no "structural damage" per the statute definition can also be accompanied by the finding of "sinkhole activity" which cannot be eliminated as being at least a contributing cause of damage. In these instances, the claim does not result in a "sinkhole loss" but "sinkhole activity" has been acknowledged to exist and can be expected to continue to cause damage to the home. At some future point in time the ongoing damage most likely will increase to the level of "structural damage" and a new claim may be warranted. Keep this in mind that the results of the inspection and testing for a sinkhole claim are only specific to the time of the testing. Results in almost all cases cannot be backdated as to when the sinkhole activity began nor can they be forward dated as to never worsening.
As confusing as the above may be, interpretation of the above criteria and the determination as to whether one or more of the above criteria has been met is a point of contention among engineers, geologists and insurance carriers.
The criteria with the most differing opinions as to what it means is Item #4. One interpretation put forth by some engineers is that Item #4 of the "structural damage" definition requires that damage to the structure must be visible at the time of the initial investigation and that this damage must be so severe that the structure is likely to imminently collapse.
Another interpretation is that damage must be present in the structure but does not have to be so significant that visible imminent collapse is possible, but that movement or instability in the subsurface soils is present and this instability is significant enough to likely cause imminent collapse to the structure. These differences in the interpretation of Item #4 are significant to say the least.
The first interpretation or theory requires a visible inspection of the structure and its damage, however, minimal if any soil testing is actually needed as visible damage to the point of imminent collapse is all that is required. The second interpretation or theory requires a visible inspection of the structure to document damage and
sufficient soil testing to eliminate the potential for significant soil movement or instability which could then translate to imminent collapse of the structure at some reasonably short term future timeframe because of the thickness and/or weakness of the underlying soils. The difference between these two theories is huge when one considers which one could have possibly prevented the Seffner tragedy or forewarned of the Orlando building collapse. If either the Seffner or the
Orlando structures were inspected for a sinkhole claim a week before the event occurred, most likely neither claim would have a positive as to Item #4 if the first interpretation were used in the investigation.
Using the second interpretation, however, it is most likely that the soil arch or bridge beneath the structure and in "the ground within the influence zone of the supporting ground within the sheer plane necessary for the purpose of supporting such building"(statute language) was explored with sufficient soil testing it would have found the soil arch to be too thin or too weak for long term support and a reasonable conclusion of imminent collapse would have been determined before the damage became severe. A positive finding for Item #4 would have triggered the more comprehensive sinkhole investigation that would have determined or at least estimated the size of the underlying soil cavity and the depth to limestone, parameters that could have allowed engineering estimates as to the scope and cost of repairs to be made before the collapse actually happened.
The above differences of looking for instability in the structure and evacuating it after the damage has manifested itself to a severe level as opposed to looking for instability in the supporting soils and stabilizing them before the damage becomes unrepairable is synonymous in some ways with the old saying of "putting the cart before the horse".
Additionally, logic could be used to state that if Item #4 requires damage to the point of imminent collapse then Item #5, at least, would have been met or Catastrophic Collapse coverage (see below) would be triggered and there would be no need for an Item #4 in the first place. Conversely, if the intent of the ambiguous Item #4 language was to address concerns of imminent collapse resulting from an unseen threat in the supporting soils, then the second interpretation makes more sense and Item #5 should be included in the statute language to address the more visible damage concerns.
Since sinkhole activity begins at the surface of the underlying limestone and progresses upward through the overburden soils toward the land surface and is dependent upon time for this progression, the depth of the initial soils investigation is directly proportional to the early diagnosis of detection as well as the extent of remediation.
Too shallow of a soils investigation will reveal no meaningful problem with the underlying soils as the soil arch may not have been sufficiently measured, while too deep of a soils investigation is an oxymoron to some extent as the more data that is gathered by deeper borings and/or testing the more accurate the interpretation of the data can be. Again, the old adage, "it is better to be safe than sorry" appears to have been written with sinkhole investigations in mind.
Lastly, when the claim about suspected sinkhole damage has reached the point of no return where a hole has developed or the house or building has sustained significant damage and one would believe that it is a no-brainer in finding a "sinkhole loss" has occurred, there is a statute definition that still has to be met. This is the one for Catastrophic Collapse coverage.
Catastrophic Collapse – this type coverage is afforded by all insurance companies coming under the auspices of the Office of Insurance Regulation (OIR). This language per F.S. § 627.706 states…..
Sinkhole insurance; catastrophic ground cover collapse; definitions. –
(2)(a) Catastrophic ground cover collapse means geological activity that results in all of the following:
- The abrupt collapse of the ground cover;
- A depression in the ground cover clearly visible to the naked eye;
- Structural damage to the covered building, including the foundation, and
- The insured structure being condemned and ordered to be vacated by the governmental agency authorized by law to issue such an order for that structure.
Contents coverage applies if there is a loss resulting from a catastrophic ground cover collapse. Damage consisting merely of the settling or cracking of a foundation, structure, or building does not constitute a loss resulting from a catastrophic ground cover collapse.
The key word in the above definition is "all". If one, two or three of the events listed have taken place, but not all four, then the definition has not been met and insurance coverage is not available under the Catastrophic Ground Cover Collapse definition. That is not to say that all four events may occur at a later point in time after the claim has been submitted and/or investigated; however, at the time of the claim investigation all four events must be in place for it to be considered a covered loss.
This leads to the question that if you have damage caused by sinkhole activity, but it has not reached the level of catastrophic ground cover collapse, how long will your home remain safe to live in before the situation may change for the worse. With respect to safety, if you believe your home is unsafe to live in, contact your local Building Official to make a determination as to whether it should be condemned or deemed unsafe for Human Occupancy. Remember, the catastrophic collapse coverage cannot be met without Item #4 of the four criteria being met.
In summary, the above synopsis of terms, definitions and interpretation of statute language goes to show that insurance coverage for sinkhole claims are being limited by legislative action that was directed to decrease the number of frivolous claims, the expense of claim investigations, and the coverages being afforded by the policy. This legislation has done that to some extent, but it has also shackled the engineer and/or geologist from actually investigating for valid sinkhole activity, limiting the data used to develop conclusions as to whether sinkhole activity may be a cause of damage, and finally, limiting the general public as to coverage for legitimate damage being caused by actual sinkhole conditions.
In order to correct some of the problems associated with the legislation, the members of FAS3 recommend that you the General Public contact your State Legislators and voice your concerns.
George C. Sinn, Jr., P.E.