Sinkholes: Fact or Fiction?

    Sinkholes consume property, cars, and people. Though sinkholes are quite common and threaten many regions of the world. As explained in the documentary, fossils from sea level fluctuations compress as part of the soil over time creating soluble and soft soil. This soluble soil allows acidic water to enter the cracks and void spaces and reach the “eroded” limestone underneath. Globally limestone is very common and susceptible to water which in turn create many sinkholes near the surface. Sinkholes are destructive, their causes are relatively impossible to fix and have various economic impacts.

    First of all, Sinkholes create destruction in many ways such as the following. Structures, roads, and railroads built above are all susceptible to these sinkholes. In “sinkhole alleys”, symptoms start to appear as cracks, driveway collapse and floods resulting from water from the caves. Many homeowners don’t have a place to go if they were to leave their uninsured property and vehicles. As a result, these sinkholes become worse destroying property and killing homeowners that have little finance to arrange another place on a more habitable land. Hence, sinkholes not only destroy their properties but also claim many lives. Buildings built on gypsum a soluble rock dissolves even faster than regular soil surface in a sinkhole-prone land. Older structures develop cracks that are usually filled up with plaster to solve the issue. But in the long run, it only makes problems worse. Similarly, salt deposits underneath soil dissolve even faster as water for irrigation is pumped through and over these deposits. Salt caverns have created several sinkholes due to cavern fracture leading to just that much damage and lawsuits as a result of the damage. Sinkholes not only destroy land, property, roads but also derail railroads.

   Causes of sinkholes include poorly designed drainage systems, damming sea and melting snow. Globally, there are millions of acres in many countries that increase sinkholes due to soluble soils. Human created sinkholes due to mining in sinkhole-prone areas, oil, and natural gas drilling or even drilling for salt not only destroys properties and land but also brings lawsuits and ultimate business closures. In fact, they can create further hazards especially when flammable and explosive elements are involved. More relevant examples include gas stations built on sinkhole-prone soils as well as natural gas pipeline running through residential and commercial areas. Natural gas, petrol, diesel etc all add up a disaster when they react in an unpredictable way due to sinkholes.

    Economic impacts include more research and development teams to analyze sinkholes. Oil spill cleanup crews and fire trucks all come in to play. Insurance companies and Geotechnical teams all play a big role in bringing solutions to the sinkhole community. Ground penetrating radar maps are already being used to detect void spaces and displaced soils round properties and roads. Hence, sinkholes have various economic impacts.

    In conclusion, sinkholes are not only destructive but devastating.  As the documentary below suggests solutions from the viewers are open to debate, one of the solutions could be using concrete caisson type structure foundation that leads all the way to the limestone base instead of grout. The water in the tunnels underneath the limestone may be pumped out using flood water pumps which could prevent any dissolving of limestone from underneath. Sinkhole prone surface soils may also be spread with a base chemical that neutralizes the acidic water making its way through the cracks and caverns to the limestone below. Since the limestone now, is stable with water underneath removed as well as the acidic rainwater neutralized, the flood water or irrigation water simply hits the limestone and fills up the void soil spaces over it like a water tank. This could be a “recycling” type solution to the sinkhole problem. Finally, waterproof drones with cameras may be used instead of divers to map out a network of water tunnels that could be initially detected with a stronger ground penetrating radar device. The best solution is “prevention” rather than cure. Home buyers may decide to get the property land surveyed for slopes, change in height and ground elevations which increase water accumulation at the foundation and increases the magnitude and speed of the sinkhole. Home buyers may either get land surveyors or survey the land themselves with some basic survey knowledge and instruments like the theodolite to find point elevation. If the soil is tested for soil plasticity before building a home on top or buying one, it could save homeowners their life earnings and savings. If one is reluctant to go through a geotechnical lab for soil tests, he/she may also perform the same tests via labs and equipment available in colleges.



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