As I majestically gaze into my backyard I notice that my perfectly flat lawn now appears to be digging a hole by itself… It seems that my yard has been sinking slowly. I decided to do a little research to stop it.
A sinking lawn is normally caused by either a developing sinkhole beneath your yard or by natural erosion due to flow of water over a given area. It may be easier than you think to distinguish the cause.
The risk of letting things lie rather than taking care of it immediately could be as simple as another inch gone by next years rainy season or as big as a crack in your foundation that could cause weakness in the stability of your home. Lets figure out if your home has a backyard river or is sitting on an underground cave.
Sinkhole Or Erosion
“A sinkhole is a depression in the ground that has no natural external surface drainage.”
United States Geological Survey
It can be caused by the slow erosion of subsurface rocks like limestone that are highly susceptible to rapid degradation. This may occur due to yard drainage in that exact spot or an underground flow of water beneath it.
It is also possible that you have a lawn depression that may not be caused by the natural erosion of stone and rather the decay of construction materials that were buried to reduce costs when building your home or any additions to the properties surrounding it.
Erosion, also called surface erosion, occurs when rapid flowing water pushes the soil from the surface to a lower point in your lawn. This may be caused by a natural grade in your lawn or by an area that water can quickly drain too. If the soil near the area is with stones, sand, or large clay particles it could be that water naturally drains to this area more readily than the other parts of the lawn. The easiest way to tell is to wait for a big rain and watch how the water drains.
A common cause of surface erosion is your gutter, and if this is your problem than check out our article about how to extend your gutter underground.
Bottom line is that if you can’t clearly diagnose it as erosion then consider the possibility that you may have a growing hole under your lawn and it warrants a little more investigation.
What Can Cause A Sinkhole?
How is this little cave growing in my yard? Lets look at some common and not so common causes.
Subsurface Rapidly Eroding Stones. All stones will eventually wear away from the constant beating of water. Take a look at river stones, they did not start off so smooth and good for skipping. Shales, sandstone, limestone, and certain volcanic rocks can rapidly erode from underground runoff(like a spring) or pooling water that will drain through the topsoil and wash over the stone.
Decaying Material. The most common culprit is buried building material that has done its time and is now plant food, however large trees, old compost mounds, old stumps, and other natural materials could be the cause of your sinkhole no matter the size. Not only does this material compress, but it also causes acidic run off when rain passes through it that can cause stone beneath to erode away even more rapidly.
Burst Pipe. A burst pipe could be filling your lawn with many gallons of water every minute without you even knowing about it. This can be noticed by either an odor near the area or by pooling water even when it is not raining. It is important that if you think a burst pipe is the cause that you call your county to figure this out, because it could cause a lot more damage or could get significantly worse.
Poorly Compacted Soil. Soil that was previously dug up from construction, installation of underground lines or any other reason could be the cause. This is less of a sinkhole and more of a slow compression of the lawn, however the results appear the same. This unfortunately demands just more soil and inherently more cost. It is important to compact the soil after you put it down to avoid the same problem in the future.
Old Utilities. This may be less common than the rest, however still important to consider. Old wells, septic tanks, or other abandoned utilities can deteriorate over time and cause large opening beneath the ground that can cave in at a moments notice.
Bottom line, that hole in your yard could very well be dangerous and if you can’t identify the cause that call a professional that can. It is important for your finances and more importantly your physical safety that you know what is happening. My intention is not to scare you, but with a little one of my own I could not help by imagine the worst case scenario as a 20ft deep hole opens in my backyard. If in doubt, just call a pro.
If a drainage system could help solve your problem by quickly and efficiently removing the water than check out this article to help you decide which drainage solution is best.
How To Solve Your Sinkhole Problem
According to the United States Geological Survey sinkholes in the United States cost on average $300 million per year over the past 15 years. There are a little under 330 million people in the US as of 2019 so you can do the math. Its important to take care of this problem before it becomes something out of one of those horror movies. Don’t worry though, there are solutions to the answers that you seek.
The most common solution to a sinkhole or depression is the fill it. It may seem obvious, but there are several non obvious things about it. Depending on the cause of your sink hole you want to follow along below:
- Remove Debris: If you have metal pieces, brick, or any other building material in your sinkhole then remove it. Likely this is the cause of your sinkhole in the first place and you want to remove it to rid yourself of any further problems. Removing an extra foot around the perimeter will help to find if there is more open area beneath the ground that has yet to cave in.
- Layer On The Soil: You, unfortunately, definitely need to fill it. Do not fret though because this is going to save you an incredible amount of effort in the long run and will stop you from incurring and extra costs on the back end. Unless you have an awkward mound somewhere else in your lawn(in this case you would be blessed), this will be the biggest out of your pocket cost of this project. Remember to mound it up a little, it is going to compress little by little as time goes on. Sometimes layering
- Compact It: Tamper it down so that this does not happen again. sinkholes are often caused by soil that already has a significant amount of air in it. Do yourself a favor and compress this soil so that you won’t have this problem later on.
- Water it. The point of this is not to get it to grow, but to get it to shrink. There is excessive amounts of air in the soil you just put in, watering it will allow it to settle more giving you a clearer picture of whether you actually need more soil or not.
- Watch It: Ensure it does not continue to sink. If it does, just fill in more soil. This, unfortunately, has one answer, even though it is an easy one. Just keep filling it in until it is level with the ground and stays that way.
- Seed It. No one wants a barren backyard. Seed it so it blends with everything else and soon you will not even know there was ever a sinkhole to begin with.
If you want to just level your lawn after your hole stops expanding and check out our article that describes how to level you lawn.
How To Stop Yard Erosion
I am sure you have been reading patiently as you want to get past the sinkhole section. Erosion is a significantly different beast in and of itself, but handle it well and you will be rid of it for the rest of your time at this property.
Dry Creek Bed: Dry creek beds can be made of stone, sand, pavers, or a combination of them. An area specifically made for rapid drainage or natural runoff is a perfect solution.
Drainage Solutions: Installing a drainage solution will not only solve you immediate problem, but will also solve the problem for years to come. A french drain, bubbler drain, or any other number of drainage solutions will improve your yards ability to disperse the water it receives.
There is any number of reasons your yard is eroding away. If this doesn’t give you some answer then please contact a specialist. Sometimes the only answer is a case by case basis and should be treated as such.