Research Report Sinkhole Insurance SinkholesSinkholes are a natural part of Pennsylvania's landscape but are a geologic hazard, particularly in the central and eastern parts of the state. Subsidence and collapsed sinkholes are found in limestone or dolomite bedrock, which is prone to dissolve over time. Open spaces within the rock allow water and soil to travel downward from the surface. Sinkholes can be a source of groundwater pollution and can become a large expense for property owners and businesses. What is a Sinkhole?A sinkhole is generally a circular hole or depression in the ground that serves as a drain for water and surface material. It can result from either gradual subsidence to form a depression in the landscape or by collapse to form an abrupt break in the soil. Sinkholes range in size from one to 30 feet in width and depth. Sinkholes in Pennsylvania are common where there are voids present in the rock below the soil. The voids were formed over thousands of years when the rock was dissolved away by rain or groundwater passing through small openings and making them larger.The occurance of sinkholes can be a dramatic event that swallows up cars, roadways and even homes. Sinkholes can also cause merely minor depressions in the earth’s surface, barely visible but highly destructive. Some sinkholes happen gradually over time while others are sudden and disastrous. A ground-shift of as little as a couple inches can be enough to severely damage the structure of a home or building, rendering it unsafe for habitation.What Causes Sinkholes?A true sinkhole is caused when the surface material collapses into a void space beneath the surface. Under natural conditions, this process occurs very gradually but can be hastened by human activities. The timing, location and extent of a collapse usually have many influencing factors.Sinkholes in Pennsylvania mostly occur in areas of limestone and dolomite bedrock. These types of rock are prone to dissolving and forming enlarged round or elongated cavities and pathways through the rock. The soil above can be lost downward into these openings, causing a sinkhole. In some places, sinkholes form in a line on the surface related to a central drain under the surface. Fractured and faulted rock may be extensively weathered, causing voids in the rock.Water is a key to sinkhole collapses. Taking water away from where it was or putting a new, concentrated source of water where it wasn’t before, can speed the development of sinkholes. Examples of new sources of water could be drainage from rain gutters, pavement, collection ditches and ponds. Treatment basins or lagoons must be carefully lined in karst terrain to prevent a sudden drainage out of the bottom and into the groundwater. Leaky water and sewer pipes can cause the soil underneath to wash away and are often the trigger for sinkholes. However, an existing sinkhole under a pipe can also cause the initial leak. Greater volumes of water moving fast into the karst system causes more soft material to be washed from the voids. Weather events can also trigger sinkholes. Sinkholes can “pop” when a heavy rain event comes after a prolonged drought.Natural or artificial lowering of the groundwater table can cause sinkholes to collapse. When the groundwater level goes down, the upper zone loses its support and can sink. When the water is lowered below the boundary between soil and bedrock, soft material is especially prone to movement into the voids in the rock below. Clay can temporarily stick together, spanning the void; but it may then fall in clumps or get washed out by surface water, resulting in a sudden, unexpected collapse. A change in surface drainage can often trigger sinkholes “primed” by changes in the groundwater table. Groundwater levels can be lowered by drought or pumping from quarries or wells.Any action that disrupts the karst system at or below the surface can accelerate the formation of sinkholes. Disrupting the surface layers by digging or construction can significantly change the waterproofing over a bedrock drain. Unsealed drill holes also allow water to enter the subsurface, possibly causing a later subsidence. Only very rarely is a sinkhole the result of a collapsed cave roof. Repaired sinkholes can reactivate and collapse repeatedly if the drain into the bedrock is not satisfactorily sealed off. A new sinkhole can appear next to one just repaired, utilizing the same bedrock drain.“False” sinkholes can appear for several reasons: mine subsidences; decaying, buried organic material such as tree roots or trash; collapse of buried relict structures; and wash-out of fill around pipes, especially due to a water main break.Dangers of SinkholesSafetySinkholes are considered a serious geologic hazard in Pennsylvania. They can appear very suddenly and without warning and may continue to grow after the initial collapse, making the surrounding ground unstable for curious onlookers. Sinkholes around gas lines can result in leaks and explosions if left undetected.Structural damageSinkhole collapse or gradual subsidence can cause structural damage and instability in buildings, roads and bridges. Repairing structures after the subsidence is difficult and expensive, and it requires specialized knowledge by the engineer and contractor doing the work. Even if a repair appears to be successful, it may not be permanent if the underlying cause of the holes remains.Groundwater contaminationGroundwater can travel very rapidly through an open karst system. Therefore, unfiltered or polluted water entering karst can affect groundwater throughout a large area in a short time. Historically, sinkholes have been used as trash dumps through which undesirable materials can easily enter the groundwater.What to do if you have a sinkholeHere are some basic guidelines to follow if you have a sinkhole on or near your property:1. Restrict access to the hole.2. Contact local police or emergency responders. Advise them if the hole is near utility lines or in a roadway.3. Take photographs for documentation, but do not get too close to the edges of a sinkhole.4. Do not allow unauthorized or inexperienced persons to investigate the sinkhole.5. Never go down into a sinkhole or attempt to fill the hole yourself.Who to contactIf you suspect that a sinkhole may be related to a DEP-regulated activity, call the DEP District Mining Office or Regional Office serving your county. If no regulated activity is suspected, you can report sinkholes to the Pennsylvania Geological Survey at 717-702-2017. Limits of DEP involvement: DEP is making an effort to prevent sinkholes resulting from permitted activities. If a sinkhole is not the result of DEP-regulated activity, the department has no legal recourse to help the landowner. There are no special organizations or funding that provide aid to those with a high sinkhole repair bill. DEP personnel will advise you to consult a geologic and/or engineering professional to assess the problem. Ultimately, landowners are financially responsible for sinkhole repairs on their property.What is Sinkhole Insurance?Many homeowners and business insurance policies offer special endorsements for sinkhole coverage. Without this additional coverage, sinkhole damage is frequently not covered. If your home or business is destroyed by a sinkhole and you do not have a sinkhole insurance policy, you will receive no compensation for your losses. This is a financial hit that most families cannot manage.Cars need coverage, too. You can get coverage for your vehicle simply by including comprehensive coverage with your car or truck insurance policy. This coverage will provide you with compensation for loss or damage caused by sinkholes as well as other common occurrences such as fire, inclement weather, falling objects and theft. Call us at Joyce, Jackman & Bell Insurors to get a quote on Sinkhole Insurance.What Does Sinkhole Insurance Cover?Sinkhole insurance will provide compensation for damages to your business or home, outlying property and personal belongings kept inside the building if they are damaged as the result of a sinkhole on your property. Even a small shift in the earth beneath the foundation of a building can cause severe structural damage. A major sinkhole can swallow up the entire building and its contents.Be certain to carry enough coverage to allow you to completely rebuild if your home or business is completely destroyed. This insurance will also cover necessary preventive measures, such as structural bracing, to keep an impending sinkhole from causing severe damage to your property.Your sinkhole insurance policy may not provide coverage for damages from mine subsidence. Call Joyce, Jackman & Bell Insurors and we will review your policy for you to make sure you are covered.