Natural disasters can be devastating, often occurring without warning and leaving destruction in their wake. One of the most unpredictable and least expected is a sinkhole. These natural depressions or holes in the ground can range from small, unnoticeable dips to massive craters, capable of swallowing entire buildings and roads.   

Due to the potential damage they can cause, it’s essential to understand what triggers them, the different types that can form, and how they’re repaired.  

Various factors contribute to the formation of sinkholes. While many are naturally occurring, human activities can also play a significant role. Understanding these causes is key to recognizing high-risk areas and potentially preventing catastrophic collapses.  

Erosion is one of the most common causes of sinkholes. Over time, the bedrock beneath the earth’s surface can slowly erode, creating underground voids. When the surface can no longer support its own weight due to the loss of underlying material, the ground collapses. This is common in areas where bedrock is composed of materials like limestone, gypsum, or salt. Since erosion is a gradual process, it can take years or even decades before a sinkhole forms, making it difficult to predict.  

Water is a powerful force, and in areas with heavy rainfall or frequent flooding, sinkholes occur more frequently. Surface water can accelerate erosion, weakening the support structure beneath the surface. After storms, hurricanes, or long periods of rain, the saturated ground is more prone to collapse. In areas that experience tropical storms, hurricanes, or frequent downpours, this is a risk to be aware of.  

While many sinkholes are caused by natural processes, human activity can also play a significant role in their formation. Construction, mining, and drilling can disturb the ground and create instability. Leaking pipes, sewers, and water mains also play a role, as water can erode the surrounding soil and rock.   

In urban areas with a lot of development or aging infrastructure, it’s important to monitor the ground carefully to avoid the risk of sinkholes forming. One common cause for a sinkhole is a trash pit. To save time and money on disposal, contractors would dig large holes on construction sites and fill them with debris, such as tree stumps, leftover building materials, and other waste. Once the pit was full, they would simply cover it with dirt, grass, or even driveways, making it look like a stable surface. Over time, these pits can become unstable as the materials inside degrade or compact.  

Fixing a sinkhole caused by a trash pit requires the removal of all the buried waste. After the trash is excavated, professionals can then fill the void with stable materials like rocks or grout to prevent further collapse.  

Underground caves or cavities, created by the natural dissolution of bedrock, are another contributing factor. When erosion weakens the roof of these caves, there is less support for the ground above. This can lead to sudden and dangerous collapses, especially if the cavity is large.   

Sinkholes come in various shapes and sizes, and they can be categorized into three main types. Each type has distinct characteristics, which influence the speed at which it forms and the potential damage it can cause.  

Dissolution sinkholes form gradually over time as water slowly dissolves the bedrock beneath the surface. Rainwater becomes slightly acidic from absorbing carbon dioxide in the air, wearing away at the rock and creating a void. Over time, this void can cause the ground above to sink. These may appear as slight depressions in the landscape. In some cases, they go unnoticed for years as they expand. These sinkholes are common in areas where limestone is prevalent, as limestone is particularly susceptible to being dissolved by acidic water.  

These sinkholes form when loose, sandy soil gradually settles into voids created by the erosion of bedrock. These sinkholes tend to develop slowly, and the depressions they create are usually smaller and more gradual than other types of sinkholes. While they may not always be immediately noticeable, cover-subsidence sinkholes can cause structural damage over time, particularly to homes and buildings. Because they form so gradually, they are often found in areas with loose or sandy soil.  

Cover-collapse sinkholes are the most dangerous type. These large sinkholes form quickly and often without warning, resulting in large, sudden collapses of the surface layer. This is usually caused by the presence of a large underground cavity that can no longer support the weight of the overlying ground. When the surface collapses, it can cause significant damage to buildings, roads, and other structures in the area, and can pose a serious threat to safety. They’re more likely to occur in areas where there are thick layers of clay or soil above the bedrock.

Repairing a sinkhole is not a DIY task. It requires professional expertise and heavy equipment to ensure that the ground is properly stabilized, and the surrounding area is safe.  

Before any repairs can begin, sinkholes have to be assessed. Professionals will evaluate the size, depth, and condition of the soil around a sinkhole. This assessment helps determine the best course of action for remediation.  

Once a sinkhole is assessed, the next step is to clear the area and fill the void. This is typically done using a mixture of rocks, grout, and concrete. These materials help stabilize the ground by filling in the gaps created by erosion. In some cases, additional stabilization methods, such as concrete piers or steel anchors, may be necessary, especially for larger sinkholes.  

If the sinkhole has caused any structural damage to nearby buildings, roads, or other infrastructure, those areas will need to be repaired. This often involves repaving concrete and reconstructing any affected structures.  

After a sinkhole has been repaired, it’s important to take steps to prevent future collapses. Regular maintenance of pipes and drainage systems can help reduce the risk of soil erosion. Additionally, proper storm drainage should be in place to direct water away from areas prone to sinkholes. In some cases, municipalities may be responsible for maintaining storm drains and other infrastructure, so contacting your local authorities is a good idea if you suspect any issues.  

If you start to see signs of sinking or cracks around concrete surfaces like driveways, sidewalks, or foundations, it’s time to call in a professional. From repaving to replacement, Concrete Solutions of Atlanta specializes in sinkhole repairs for concrete, offering assessments and solutions to sinkhole damage. Contact us today to schedule our services!