Sinkholes: Preventing a Sinking Site

understand what's underneath trademark trinity subsurface
Evan Mowbray

Sinkholes: Preventing a Sinking Site

It’s important to understand the full scope of a work site when it comes to knowing what’s underneath your projects. However, sometimes the underground sneaks up on unsuspecting areas, bringing the surface and subsurface together. I’m talking about sinkholes, which can happen anywhere where water meets the ground. Sinkholes are formed when the ground collapses due to water seeping through the soil and accumulating in cavities and voids. These cavities weaken the soil’s ability to hold weight, leading to collapses in the Earth through internal erosion. Sinkholes can be naturally occurring, or caused by human activity. There are a few signs of naturally occurring sinkholes, such as cracks in a foundation, the inability to close doors and windows, and increasing ground settlement. Overusing groundwater in times of droughts, building artificial ponds and drilling water wells can all result in sinkholes caused by human activity.

An image of a site plan showing ground penetrating radar data for sinkholes. The text reads "GPR data showed void spaces beneath the surface, indicating that there was a risk of subsidence. The exact location and depth of the sinkholes were identified from ranges from 2-6 feet and the data was used to create a map of the subsurface features.

Sinkholes have formed in unexpected areas in various sizes, both on the surface and in the water. The deepest sinkhole in the world, known as the Xiaozhai Tiankeng sinkhole in China, is over 2,100 feet and formed due to a flowing underground river thousands of years ago. Sinkholes can form anywhere, such as the more recent sinkhole formed at the Corvette Museum in 2014, which caused a partial floor collapse that led to over a million dollars in damages to eight unique Corvettes. They can occur both outside and inside, wherever water can get into the dirt. Oftentimes, the presence of sinkholes is often undiscovered until one forms and swallows up something important, such as a business parking area, construction site, or even someone’s house.

In order to locate potential sinkholes and understand the danger, we can utilize GPR technologies to get a better idea of potential sinkholes. Ground penetrating radar can be used to locate a number of underground features, including utilities, tanks, and graves, but can also be used to locate the voids and cavities. Our team at Trinity is familiar with ground penetrating radar and locating potential sinkholes. In one case, our team was called out after a sinkhole formed in a parking lot of a country club and swallowed a car. The client took action to repair the sinkholes and called on our team to determine the potential for more sinkholes. Through the use of ground penetrating radar, we were able to map out and confirm the presence of two additional voids underground in the parking area that would turn into sinkholes due to subsidence if not properly addressed.

An image of a truck sinking into stone at a construction site as a result of a sinkhole. The right side of the truck is sunken into the ground, and the left side of the truck is partially in the air.

Another sinking situation occurred at a construction site where a sinkhole had already formed. While the client was working on filling in the sinkhole, the truck carrying the stone sank into a different sinkhole due to its weight overwhelming the soil. In order to retrieve the dump truck safely, our team was called out to inspect for sinkhole activity before a tow truck was brought in. Our team was able to gather the scanning data necessary to determine the presence of potential sinkholes that would result in another sinking truck, allowing the client to repair and reduce their sinkhole risk. Our team at Trinity Subsurface is highly skilled at using ground penetrating radar to locate both sinkholes and other subsurface features, such as utilities, tanks, and graves. Call us today to find out more about how you can locate potential dangers and visit our website for further information.

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