A sinkhole is a cavity in the ground, especially in limestone or bedrock, caused by water erosion when water burrows through loose layers of soil or soil that is poorly compacted to create underground voids. When these voids become big enough, the “roof” of the hole sinks in, since it is hollow underneath, creating what we call a sinkhole. While some sinkholes can be extremely large (some even big enough to engulf a car), the sinkholes we typically see in parking lots range from about the size of a golf ball to about basketball size, and are usually near catch basins, walkways, or building foundations. Regardless of their size, sinkholes are a big potential liability and safety issue, so having them repaired immediately is important.
Difference between a sinkhole and a pothole:
Making the differentiation between a pothole and sinkhole is important, because the repairs will differ significantly for each. A sinkhole is a closed natural depression in the ground surface caused by removal of material below ground, whereas a pothole is usually caused by failure of paving materials (very common during/after winter).
How to repair a sinkhole vs. a pothole:
The most common pothole repair methods include patching and saw cutting and replacing. But, when dealing with sinkholes in your lot, this issue cannot simply be treated by filling in the hole or patching the asphalt around the catch basin. The reason why simply applying a “Band-Aid” to the sinkhole issue is not a permanent solution, is because the reason this sinkhole was created in the first place was due to erosion coming from the drainage structure and the surrounding base material and stability. This means that if the actual source of the problem is not fixed, then it will happen again and/or get worse. Essentially patching a sinkhole will not provide much benefit at all, other than temporarily masking the problem.
Sinkholes In Catch basins:
- It is not uncommon for your catch basins to need adjusting overtime to ensure that they are working properly and draining water from the surface of your asphalt. Just because the surface may look ok, it doesn’t necessarily mean everything underneath is all good. So, do not wait until you notice a major issue before having your drainage system or catch basin inspected.
- A sinkhole near a catch basin is often a sign of a damaged catch basin.
- Sinkholes can also form in areas adjacent to catch basins due to corrosion or collapsing of the pipes that carry the water, leading to destruction of the stone base.
- In this situation, we will likely need to fix the structure and replace your catch basin.
Sinkholes Near Or Under Walkways:
- If sinkholes are found in or under walkways, this is a serious tripping hazard.
- Finding the source of the issues is still key to an appropriate repair.
- If your walkway is concrete instead of asphalt, there are some things you can do to adjust sunken concrete slabs back to a normal level, like concrete jacking.
Sinkholes Near A Structure’s Foundation:
- This is extremely worrisome, because the structural integrity of your building is at stake.
- If sinkholes are occurring near the foundation of your commercial building, or your home, this is likely a sign that your drainage is not working correctly and not channeling where it should.
- It is important to have an immediate inspection done to determine whether being inside the building is safe or not, depending on the severity of the depression.
Preventing sinkholes before they happen:
As always, preventative and proactive maintenance and repair is the best way to sustain the life of your asphalt and to prevent big issues like sinkholes from occurring. It is important to regularly check around your catch basins in your lot to see if there are any major defects, depressions, or other potential weaknesses within 3-5 feet around the cover.
Protecting your property and the people that reside on it, or frequent it, is extremely important. The first step is installing your asphalt parking lot properly with a well and properly compacted base. From there, regular repairs and maintenance is the most important action is preserving your asphalt and keeping your lot safe and beautiful! If you think your lot may be suffering from a sinkhole, or you cannot tell if it is a sinkhole or pothole, EastCoat Pavement can help! We can also provide you with a regular repair and maintenance schedule that’s best for you and your lot. Contact us today for your free consultation!