Sinkholes are the result of collapsing underground bedrock, leaving behind a hole. They occur in nature but also can be a result of humans cutting down trees and leaving rotting stumps behind, or because of buried construction debris. Sinkholes come in all sizes, causing safety hazards in your backyard, as people are likely to trip, twist an ankle or, in the case of larger holes, fall in. Because of these dangers, you should repair sinkholes as soon as you notice them. You must also distinguish a do-it-yourself sinkhole repair from a more complex problem, which only a professional can handle.
Inspect the inside of the sinkhole with a flashlight. Do not step directly on the edge of the hole, as the surrounding ground may be unstable. Look for rotting tree stumps or old construction debris. Remove any debris inside the sinkhole, using a shovel and staying a safe distance away from the edge.
Shovel away the outer edges of the sinkhole, opening it up and making the hole larger. This lets you know whether the sod is covering an even larger void beneath the surface. Continue to shovel away the edges of the sinkhole until the ground beneath the sod is solid.
Fill the sinkhole with a few inches of soil. Use an iron bar or the top of a sledgehammer to pack the dirt down firmly into the hole. Continue filling the hole with soil and firmly packing it until you reach the top of the sinkhole. At the surface, use a hand tamper to pack the topsoil in place.
Water the filled-in sinkhole thoroughly. Watering helps the soil to settle and lets you know whether you need more dirt to fill in the hole.
Wait two to three days, and check the filled-in sinkhole. If the soil has settled and a shallower hole is beginning to form, fill the hole in with more soil and pack it down. Repeat this process, as needed, until the soil has completely settled and the hole is filled in.
Things You Will Need
Iron bar or sledgehammer
Repairing large or deep sinkholes is not a job for the average handy homeowner or gardener. If a large sinkhole appears in your backyard or if the hole threatens the foundation of your home or other buildings, immediately rope off the area, and contact your homeowner insurance company. In some cases, sinkholes are fixable only with the help of a professional, such as a landscaper or geologist. Sinkholes might also be the result of plumbing and drainage issues. Call in a professional if you find that your sinkhole is filling with water.
Do not plant gardens, shrubs or trees in areas of your backyard where you’ve experienced sinkholes. Trees and shrubs run the risk of falling if the ground begins to settle. Lack of water and oxygen as the result of the ground sinking and settling causes damage to the plant’s root system.
Once a sinkhole is discovered and examined, the repair method depends on the size, stability, location, geological context, and the immediate cause of the sinkhole.
In general, a hole that’s very small and very stable in an open area can simply be filled with dirt and restored with ground cover.
A larger hole in an open area is likely to need excavation down to some sort of bedrock for stability, and then a filling operation with layers of rock, gravel, dirt, and possibly grout.
In open areas, it’s always important to determine the depth of the sinkhole and whether the bottom and sides are stable. These tests are carried out using a sturdy stick as a probe.
Initial evaluation is more difficult when a sinkhole occurs underneath any kind of structure. A geological engineer must use specialized equipment to determine the nature and extent of the sinkhole event. Once this is accomplished, the engineer develops a plan to stabilize and restore the building. This plan usually calls for grout of some kind to be pumped under pressure to fill voids and compact soil with rocklike material. This process will be carried out through various techniques of injection grouting that are appropriate to the situation.
Depending on geological conditions surrounding the hole, many different geotechnical approaches could be called upon. But in every case, the goal is to find or create a solid support underneath whatever is on the surface, including ground cover, homes, or buildings.
The repair process always begins with safety. You can learn some appropriate precautions here.
Sinkholes are defects or depressions in the ground’s surface which can be caused by natural or artificial processes. The major causes of sinkhole formation include:
that result from poor groundwater drainage
- Rechanneling activities that lower the water and leave overlying ground layer unsupported
Sinkholes will cause the loss of integrity of a ground surface and can have dire effects on overlying building and construction installations.
This article will detail ways to identify sinkholes, outline the various types and discuss the best sinkhole remediation techniques.
How to Identify a Sinkhole
When most people think of sinkholes, they imagine the type from movies that unexpectedly opens and swallows a car. In most cases, sinkholes appear gradually and give plenty of warning before their advanced onset.
There are ways to assess and predict the risk of a sinkhole occurrence. The key danger signs to watch out for are listed below.
For building structures:
- Jamming or increased difficulty opening and closing doors or windows
Within the property environment:
- Formation of gullies, small ponds following rainfall
- Re-emergence/exposure of previously buried structures e.g. tree roots, building foundations
- Poor growth/death of vegetation over the ground surface due to the erosion of nutrient-rich topsoil
3 Different Types of Sinkholes
Depending on the mechanism of formation, three major types of sinkholes are recognized. These are the solution, cover-subsidence, and cover-collapse sinkholes.
These sinkholes form in areas where water has dissolved limestone underneath the topsoil. With the onset of limestone dissolution, natural crevices in underground rock formations widen. The topsoil is then pulled by gravity into these defects, creating depressions in the ground surface where rainwater may collect, forming ponds.
This type of sinkhole is unlikely in the Greater Houston because of the soil content.
Poorly compacted topsoil with loose aggregation (especially sand soils) is at particular risk of this type of sinkhole formation. These soil particles track downwards into defects in the underlying bedrock formations leaving large defects on the ground surface.
These are also termed “dropouts” as the ground surface collapses, creating large breaches in the surface continuity. Although cover-collapse sinkholes appear dramatically, the process leading to their occurrence is more gradual.
When the thinned topsoil roof is no longer able to sustain its weight, a collapse occurs creating a large sinkhole. A sinkhole like a cover-collapse in Greater Houston is likely the effect of major leaks in underground infrastructure.
These are rare, and the URETEK team does not provide solutions for this type of sinkhole.
The kind of sinkholes we frequently see appear gradually and are typically caused by water leaks. It could be water from:
- An under-slab plumbing leak
- Water leaking from municipal storm/sewer lines and manholes
- Water from a lake/ocean that pulls soil into the lake/ocean because of a leak in the bulkhead
Can Sinkholes Be Repaired?
Depending on the extent of damage, various sinkhole repair methods can be utilized. While a small-sized sinkhole can simply be packed with dirt and covered with a soil layer, an extensive surface defect will require more specialized sinkhole remediation methods.
2 Common Sinkhole Repair Methods
Understanding how to repair sinkholes may depend on the type of sinkhole. The URETEK solution is generally to seal and fill the void.
- For leaks from under a concrete slab, we would locate and repair plumbing leak, then inject our expanding polymer to fill voids and stabilize soil.
- For a leaking municipal storm/sewer, we would inject our polymer to seal the leaking area and fill the void space created by the leak.
- For a leaking bulkhead, we would inject where the leak is allowing the polymer to fill the leaking joint and inject it to fill the void space.
The most popularly employed techniques to achieve these repairs are listed below:
Grouting involves the use of concrete or other chemical substances to fill subsurface defects. If expertly done, these solutions for sinkholes will seal off breaks in the continuity of the underlying bedrocks and restore stability to the affected areas.
Cement grout is used to fill the sinkhole defect. A significant drawback to this method is the fact that cement-based grout may be required in excessively large amounts as defect size may be underestimated.
Chemical grouting uses a stable expansive material to achieve sinkhole repair. An effective example of chemical grouting is void-filling foam. This unique polymer is pumped into targeted sinkhole cavities to eliminate dangerous voids. Polyurethane foam is particularly advantageous while filling voids under concrete slabs due to its expanding properties. It spreads into hard to reach cracks and crevices, resulting in a stable, more permanent grout layer.
Contact the foundation soil stabilization contractors at URETEK Gulf Coast today for help.
The use of underpins to support a building structure’s foundation is an effective way of tackling sinkhole under a house. These pins are driven beneath the ground surface to the point of refusal to achieve stability and prevent further settling of overlying structures.
This is the concept behind pressed pilings foundation repair, where concrete cylinders are used to stabilize your subsiding foundation at its perimeter. The pressed piling system used by URETEK Gulf Coast reaches a deeper soil base that isn’t as vulnerable to poor and inconsistent environmental conditions like sinkholes.
Who Fixes Sinkholes?
URETEK Gulf Coast provides the best foundation repair solutions for both residential and commercial buildings. Our unique sinkhole repair techniques will ensure that you get the most effective void elimination solutions.
If you’re in Houston and you’d like to learn more about our highly effective residential or commercial foundation repair, please contact us online today for a free estimate!
TORONTO – The presumed death of a Florida man who disappeared as a sinkhole opened under the bedroom of a house has people wondering how much of a risk such holes could be.
Sinkholes are common in seaside Florida, whose underlying limestone and dolomite can be worn away by water and chemicals, then collapse.
According to the Florida Geological Survey (FGS), “acidic ground water slowly dissolves cavities and caves in the limestone over a period of many years.”
“When the cavity enlarges to the point that its ceiling can no longer support the weight of overlying sediments, the earth collapses into the cavity,” explains the FGS website.
So what are some warning signs? Florida’s Lake County engineering department provides a list:
• Fresh exposures on fence posts, foundations or trees caused by the ground sinking
• Slumping, sagging or slanting fence posts, trees or other objects
• Doors and windows that stop closing properly
• Small ponds of rainfall where water hadn’t collected before
• Wilting of small, circular areas of vegetation
• Cloudy water instead of clear water pumped from nearby wells
• Cracks in walls, floors, pavement and the ground surface that’s different from a few hairline cracks normally seen between concrete blocks
But there may not always be warning signs.
Pierre Robin, a geology professor at the University of Toronto, says you cannot always predict when the ground will collapse.
“The rock under the ground has to be soluble, and the water has to be available to dissolve it and take it away in solution,” he told Global News. “It’s a small hole that progressively becomes a big hole….it occurs over thousands, tens of thousands, millions of years.”
So how can you fix a sinkhole?
If it’s a small hole, the FGS says to fill it with clean sand or soil. The FGS says not to use waste or anything that could potentially release toxins into the groundwater.
If the sinkhole is larger, broken limestone or a concrete plug in the bottom of the sinkhole is suggested to help create a foundation for the fill. Then add clayey sand to prevent water from seeping down and top it off with sand and top soil, says the FGS.
“Additional fill may be necessary over time, but most holes eventually stabilize,” reads their website.
Why Florida Sinkholes Should be Repaired ASAP
Sinkholes are a major issue for Florida homeowners. If one opens up, it could swallow part of your home, your car, your garage, or even yourself. Sinkholes pose a serious risk to both life and property.
Sinkholes also significantly lower the property value of your home. If one opens up beneath or near your foundation, it could cause serious structural damage to your home, and may lead to foundation sinking or settlement. Therefore, sinkholes need to be stabilized immediately as soon as they’re detected.
Sinkhole remediation is a complex procedure that only professionals should attempt. The sinkhole repair team at Foundation Professionals of Florida has the necessary expertise and equipment to make sure your sinkhole vanishes forever, and not your home.
Which is the Best Florida Sinkhole Repair Method?
The location and size of a sinkhole determines which repair solution is chosen. The main sinkhole repair method in Florida is pressure grouting with either a cement grout solution or a polyurethane grout solution. However, in some cases, underpinning with foundation piers is used along with grouting to stabilize foundations affected by sinkhole formation.
In most cases, the sinkhole will be filled using some kind of pressure grouting technique. However, whether or not piers are needed to stabilize the foundation depends on where the sinkhole is located and what kind of damage it has caused the foundation. If you have a sinkhole in your yard or driveway, grouting alone may fill in the void and stabilize the surrounding soil. However, if the sinkhole is underneath your foundation, you may need underpinning services as well in order to lift the foundation.
Our team at Foundation Professionals of Florida is skilled in both underpinning and grouting techniques, and will help you choose the right one. To learn more about the benefits of grouting or underpinning for sinkhole repair and stabilization in Florida, see Grout vs. Underpinning: Which Is Right For You?
Are you worried about a possible sinkhole on your property? Contact us today for a free estimate.
Sinkholes are commonly found in areas where a large portion of the sediment consists of salt beds, gypsum, and limestone rock. These dissolve once excess moisture sifts through the topsoil and into the sediment. Major sinkhole issues take a long time to develop. Sinkholes are often portrayed as massive, street swallowing disasters, but can be a simple foot wide safety hazard on your property. Minor sinkholes can be easily corrected by the proper contractor.
At Drainage & Erosion Solutions, we have performed numerous fill-ins and repairs involving cases of sinkholes. In our years of experience as the top waterproofing company in the Northern Virginia area, we’ve learned that sinkholes can cause serious damage when left unrectified. Below we’ve elaborated on some of the reasons it’s best to call in an expert to deal with your sinkhole issue.
Other Reasons Why Sinkholes May Form
- Poorly Compacted Soil: Soil that is improperly packed around the external structure of your home can end up forming a sinkhole, as water and pressure will eventually cause settling and create a depression.
- Debris That Is Buried/Rotted: Vegetation or stumps left aside after landscaping will also settle into the soil over time creating a void beneath the ground that can eventually form into a sinkhole.
- Leaky Water/Sewer Pipes: Excessive amounts of water beneath the ground can lead to surface depressions, which can be caused by a leak in your house’s water or sewer line. This is a major issue that would develop more rapidly than more naturally occurring sinkholes.
Why You will Need a Professional to Repair Your Sinkhole
Some sinkholes are easy to fix by simply filling them in and properly compacting them, others can be hazardous to deal with.
Whenever you see a sinkhole, you’re looking at it from the surface, depending on the extent of the damage, there could be more to the issue than meets the eye. Sinkholes of any size can be dangerous, especially to children or pets.
Sinkholes can form in the vicinity of highly sensitive infrastructure, such as your electrical lines, sewer pipe, or water line. This can make it difficult to perform the correct techniques to safely fill it in. DES would ensure that any plumbing or engineering consult would be called in to assess the problem from every angle before proceeding.
Lack of Required Equipment
In some extreme cases, a sinkhole will cause damage to your foundation, exterior wall, or exterior stairs due to its proximity to these structures.
For example, sinkholes that develop under sidewalks will tip the concrete at a pitch, where it will break or continue sinking. In this case the hazard created is one of falling/ injury towards pedestrians.
Drainage & Erosion Solutions: Quality Waterproofing Company in Arlington, VA
Sinkholes are a serious hazard for homeowners and should be addressed as soon as possible. They almost always form around the presence of excessive amounts of water within your property. Though you can fill in most minor sinkholes, for those that appear more problematic, call a professional sinkhole fill-in and expert waterproofing company like Drainage & Erosion Solutions of Arlington, VA. Our team has over 40 years of experience in the drainage, waterproofing, and erosion response.
Contact us at (703) 534-1949 to learn more about what makes us the best drainage and waterproofing company in Northern VA.
Sinkholes are a fact of life in many parts of Florida. Whilst professional assessment of an area’s geology and history can estimate the risk of a sinkhole forming, there are no guarantees.
Given this, what options for remediation are there if a sinkhole does occur? Do they carry on growing indefinitely? Can they be filled in?
Can you fix a sinkhole?
The good news is that sinkholes can often be repaired, although it is a bit more complex than just filling them in.
The aim in any sinkhole repair is to reduce the danger of further collapse, support any surface structures, and avoid promoting new sinkhole formation nearby. The process to achieve this is designed on a case by case basis and generally requires professional advice, as every sinkhole has a unique set of conditions including shape, depth, surrounding geology, connection to groundwater storage, and safety requirements on the surface.
In remote areas where the sinkhole is not endangering anything on the surface, the decision is sometimes taken to fence off the area and leave the hole open. As a sinkhole is a natural geological feature relating to water flow, by interfering with it, drainage pathways can be altered, potentially increasing the likelihood of sinkholes forming elsewhere.
However, in many cases, leaving a sinkhole open is not safe or practical. As sinkholes can link directly into groundwater, it may also be necessary to protect underground water stores from pollution – especially if people start using it as a place to dump their trash, or unwanted agricultural materials. To repair a sinkhole, engineers have a number of options available.
Safety is paramount with sinkholes, so after the discovery of a hole, the area is usually fenced off to keep people away, and properties affected may be evacuated (the Florida Department of Environmental Protection has advice on what to do if you find a new sinkhole).
Once a sinkhole is safe, it can be professionally assessed for size and stability, along with the likely cause of the collapse and the surrounding geology. Small shallow stable holes are sometimes simply filled in with clean sand and soil.
Larger holes that are not underneath a house or other structure on the surface are often excavated down to the bedrock at the base and sides to remove any material that could collapse further. They can then be filled, frequently using a graded fill working from larger rocks at the bottom, up to soil at the top. By using a fill made of separate pieces of rock, rather than a solid mass like concrete, natural drainage can continue.
If the sinkhole is under a house, or other structure, then assessment and repair is more complicated. First the depth and spread of the sinkhole is assessed using remote sensing and geophysical techniques. Then a case-specific plan is developed by specialist engineers. As excavation is not usually practical in these circumstances, fluid grout based on either special chemicals or cement is often used as the fill instead. In many cases this grout will be injected into the sinkhole under pressure, so that it fills not just the main hole, but also penetrates into other cracks and linked holes in the bedrock, and through the overburden and soil to create a solid, stable mass. Sometimes injection of the grout can show that one sinkhole is linked to a much larger underground network, as the liquid cement disappears down into the sinkhole drain.
Sinkholes are often directly connected to groundwater, which in turn is connected to local rivers and wetlands, as well as being used for drinking water supply. It is therefore important that they are fixed in a way that minimizes environmental damage. In Florida an Environmental Resources Permit may be required before filling a sinkhole, depending on its location and nature – the Department of Environmental Protection provides advice on this. It is vital that sinkholes are only filled with clean approved materials, and not trash, or anything that might cause pollution.
Can sinkholes be prevented?
Sinkholes are a natural part of the landscape in any region underlain by limestone or evaporites. However, some activities can cause sinkholes to form or collapse more quickly.
One of these is pumping too much water out from underground. Many of the underground voids that become sinkholes are normally filled with water, and the pressure from this keeps them stable and intact. If the level of groundwater drops, either due to a drought, or increased extraction for use, then the void can become unstable and collapse. Furthermore, removing water from one place can change the composition and flow of groundwater in another, making sinkholes more likely. A famous and spectacular example of this is the Dead Sea in the Middle East, where the salty waters of the sea are receding at up to 1 m a year, due to water extraction from the River Jordan. As the salty waters recede, fresh water is pulled into cracks in the rocks, where it dissolves new and larger holes.
Another cause of sinkhole destabilization is changing the way water flows or drains on the surface. If water from a wide area is diverted into a much smaller area, then this can increase the drainage into the rocks at a particular point and speed up sinkhole formation. Water is also surprisingly heavy, so the creation of new ponds on the surface, or really heavy irrigation can cause a sinkhole to suddenly collapse. Excavation for construction projects, and development of new buildings can also increase the risk of sinkhole development, both by changing drainage, and by increasing the weight on the ground surface.
It can be seen then that whilst sinkholes can’t be prevented, there are factors that governments, companies and communities can take into account to reduce the risk. This is one of the reasons that fixing a sinkhole needs careful professional assessment and planning – the aim is not just to fill the current hole, but to reduce the risk of further problems later.
Guest blogger Dr Alison Blyth is an earth scientist with a particular interest in karst.
The content in this blog is an overview provided for general information purposes only, and does not constitute professional advice. The author does not accept any liability arising from the use of the information provided here or from the omission of information.
The Atlanta and surrounding areas certainly have their fair of sinkholes. Sinkhole repair takes the expertise of someone qualified.
Sinkholes can develop anywhere on your property. The majority of the ones we see are in the front or back yard. It’s not uncommon to find a sinkhole under the driveway.
In rare cases, the sinkhole can go under the foundation of your house or garage. Sinkholes come in all shapes and sizes. The majority of them are rectangular shaped, averaging 30-40’ in length and 12-15’ wide. They average 15-20’ in depth.
Have you ever noticed a wide sinking area in your driveway or yard? There is a good chance it’s a trash pit that was used during the construction of your home.
Contractors use these to dispose of trees, stumps, and other trash when constructing your home. These holes can be costly to the resale of your home as well as dangerous for your family, friends, and pets.
Check out this news article from 11 Alive – New legislation could put teeth in trash pit sinkhole accountability
Sinkhole Repair Projects – What To E xpect
Typically, when we start excavating, we find decomposing tree debris. Occasionally we will find construction materials that were buried. Many times, the debris will be 8-10’ below the surface because over the years dirt has been added to the top to level off the area. We must remove all debris and organic material and install new structural fill (dirt, gravel, flowable fill) then properly compact the area. We also recommend a third-party inspection by an engineer. We work with several engineering firms around Atlanta and can help arrange this for you.
Signs of a sinkhole under a driveway. Sinkhole during process.
Can A Sinkhole Be Repaired?
Can I repair a sinkhole by myself?
Proper sinkhole repair requires an expert. Unfortunately, many people waste a lot of time, effort and money trying to repair a sinkhole themselves. Some homeowners will continue to pour dirt or other materials in the sinkhole.
This method is improper, dangerous, and will actually speed up the decaying process. This will not fix your issue. If dirt is simply added to the sinking area, it will only add more weight to the weakened surface and actually cause it to sink even faster, especially when it rains.
The only way to properly repair a sinkhole is to remove the source, which requires excavation and fully cleaning out all debris. New fill material must be properly installed and compacted. The sinkhole will not go away until the underground debris is fully cleaned out and removed.
Excavation of a sinkhole Professional Sinkhole Repair and Removal Sinkhole size perspective Proper procedure to fill and repair a sinkhole Sinkhole filled and repaired with final landscaping The process of excavating a sinkhole and the proper way to fix, fill, and landscape.
Why Choose Sinkhole Atlanta
The owner, Brandon Sewell has over 20 years of experience in sinkhole repair. You don’t have to worry about meeting a sales guy and then wonder who will show up to do the work. You will meet Brandon on your original estimate and deal with him throughout the entire process.
There are many landscape and concrete companies that attempt sinkhole repair but we are the only company in Georgia that specializes exclusively in sinkhole and trashpit repair. Our experience has shown us that any remedies other than complete removal off all debris is simply a waste of money. Unfortunately, many of our customers have attempted repairs or had an unqualified company remedy the situation only to have it show up again usually within a few months.
We are a full-service company. Depending on where the sinkhole is located on your property, if there is a need, we can replace your driveway and repair your landscaping. We pride ourselves on being as neat as possible during construction all the way through final cleanup.
We successfully remedied sinkholes under homes, businesses, pools, driveways and just about any other location you can think of. We offer a lifetime warranty against shifting or settling.
The best method of sinkhole repair varies with the size and stability of the hole. For a smaller hole with firm ground at its lowest level, replacing dirt and repairing ground cover will suffice. Larger holes where the landowner can excavate to bedrock can be repaired by layering varying sizes of stone topped by gravel and dirt. Sinkhole repair for very large holes with unstable sides or low points should be carried out by professionals.
A sinkhole is a depression in the ground caused when ground water erodes subsurface rock allowing the dirt above it to sink. These holes range in size from about 3 feet (0.9 meters) wide and deep to 300 feet (91 meters) wide. Sinkholes can occur almost anywhere, but are most common in the southeastern United States. Manmade sinkholes are common as well, occurring when a depression in a piece of property has been filled with trash, branch cuttings or other debris and does not provide adequate subsurface support. Sinkhole repair methods are the same regardless of the cause of the hole.
Begin the process of sinkhole repair by testing the width and depth of the sinkhole with a long, sturdy pole or stick. If the hole is very large, the best method of repair likely is contacting a professional contractor who can excavate to bedrock and fill or reinforce as needed. If probing the extremities of the sinkhole with the pole does not lead to a firm base and sides, a professional should be called as well.
A smaller sinkhole in a residential property of about 3 feet (0.9 meters) wide and deep with a firm base and sides can usually be repaired by adding dirt. The property owner should layer in a few inches of dirt and tamp it down firmly. Repeat that process until the tamped dirt has filled the hole to surface level. If ground cover was lost, it should be replanted.
Sinkhole repair for a large depression, one of about 3 feet to 6 feet wide and deep (0.9 meters to 1.8 meters) in which the property owner can excavate to bedrock, involves layering in rock, sand and dirt. Begin by covering the bottom of the excavated hole with a layer of stones about the size of cabbages. On top of these stones, place a layer of smaller stones, about the size of billiard balls. Fill in the layers of stone with a layer of gravel.
On top of the layered stone, place a synthetic construction fabric, also known as a geotextile, over the gravel. This is a sturdy, stretch-resistant fabric that will help prevent layers of sand and dirt from washing away through the stone layers. Layer sand on top of the construction fabric and layer soil on top of the sand to ground level.