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Plumber that repairs sinkhold drainage problems
A sinkhole should be repaired as soon as you notice it, it means the plumbing under the ground has failed and it could collapse even further if left unrepaired. This could cause damage to property or harm people walking past.

What is a sinkhole?

In the simplest terms a sinkhole is an area that opens up in the ground that literally creates a hole. For a home if your plumbing fails or collapses you might see a small sinkhole appear in the garden, around paving, or in a driveway. They can be small and other times they can be large enough for a vehicle to fall into. It just depends what plumbing has been installed under the ground and how big the damage is.

People get surprised about sinkholes appearing but they build up over time as the pipes under the ground begin to fail or the earth moves. In natural environments sinkholes occur when water travels through dissolvable rock such as limestone or gypsum. As more water travels through the rock, it creates voids underground that eventually become so big the ground above collapses, creating the sinkhole.

If this happens around a home then the results can be a disaster as it can shift or move your home’s foundations and cause a portion of it to sink in the ground. If the foundations move then so can the walls and this means tiles may fall off, waterproofing might fail or even a roof or wall collapse depending on the severity.

Under the surface of any suburb in Sydney are thousands of pipes and drains, some are for water, some are for sewerage and others are for stormwater. If these become too old or aren’t taken care of they can crack which leaks water into the surrounding soil. The soil in the area then quickly becomes oversaturated which leads to erosion and once this happens the area deteriorates quickly. Over days, months or even years, voids form and if they become large enough the ground above eventually becomes so weak it collapses, creating a sinkhole.

Sinkholes can also be created by;

  • Broken septic tanks
  • Buried rubbish
  • Soil that was not properly compacted after excavation work
  • Humans cutting down trees that leave rotting stumps and root systems the break down in the earth.
  • Buried construction debris that breaks down over time. 
In Sydney the most common type of sinkhole that a plumber will repair is one that was created from stormwater pipes or sewer pipes failing. You will notice it if you see wastewater or smell foul odours in a particular area. Either way a sinkhole is a safety hazard as people are likely to trip, twist an ankle or, in the case of larger holes, fall in. Therefore it is wise to get a sinkholes inspected as soon as you notice them. 

What types of sinkholes appear in Sydney?

As we mentioned a sinkhole is a hole or depression in the ground caused by some type of collapse of the surface-layer sediment into the ground. There are two main types of sinkhole;

  • Cover-subsidence sinkholes occur where a layer of soluble rock has been worn away underground, and the soil then fills it in – causing a large depression at the surface level. These are the types of large sinkholes that often create caverns and eventually turn into tourist attractions.
  • Cover-collapse sinkholes occur when storms, flooding, or drought quickly removes a material in the ground, causing the surface-level sediment to suddenly collapse into the void. These sinkholes can appear very quickly (within minutes), and can therefore be very dangerous.

These are naturally occuring ones, but most of the ones we see in Sydney are from human activity or poor or faulty sewer line repairs. You must also distinguish a do-it-yourself sinkhole repair from a more complex problem, which only a professional can handle. To get it repaired requires licensed professionals which may include an engineer, architect, builder or plumber depending on the location of the sinkhole and the type of damage it has caused.

Can you get a sinkhole near a home in Sydney?

Most of the time you might see a sinkhole appear on the news because the hole is so huge that a car or truck fall into it. Although believe it or not they happen all the time and are usually small ones around a home or building. If you are worried about a sinkhole near your home these are the things to keep an eye out for;
  • Fresh wall cracks forming inside and around your home
  • Cracks and/or holes suddenly appearing in the ground around your home
  • Trees and/or fences tipping over and/or falling
  • Depressions forming in the ground in the backyard or around a stormwater drain
  • Doors and windows becoming difficult to open or shut

Can you get a sinkhole inspected in Sydney?

Instaplumb can send out a licensed plumber to inspect your sinkhole in Sydney. Our team is available 24 hours for all types of plumbing emergencies and can visit a property to see what might be causing the sinkhole. Once we have assessed the site we can work out what is the best cause of action to get it repaired.

The way to ensure a man-made sinkholes doesn’t open up on your property is to have a local plumber in Sydney inspect your underground sewage pipes and your storm water system for any cracks, breaks or leaks. They can also make sure that the drain pipes from your roof are not emptying onto the ground and into the storm water system correctly. You have to keep an eye out for things like sagging trees or fence posts in your yard, as well as doors or windows that no longer close properly, as these might be signs of an imminent collapse and formation of a sinkhole

How can you get a sinkhole repaired in Sydney?

A property manager in Ramsgate needed a licensed plumber that could help repair the sinkhole damage on a strata managed property. The sinkhole had been created because of the stormwater plumbing collapsing. Instaplumb sent a local plumber to the location in Ramsgate to do an assessment and understand the extent of the problem. 

The strata body corporate had already engaged an engineer who had inspected the property and presented a set up plans that would require the removal of the collapsed plumbing system and the installation of new piping. We therefore didn’t need to conduct a CCTV camera inspection of the pipes.

There was no prior warning or evidence that the piping was about to collapse and because it was completely destroyed it meant it wasn’t possible to repair other than installing an entire new stormwater system to collect water run off as per the engineer’s hydraulic design.

So Instaplumb was engaged to install new stormwater pits to catch water run off and divert it to the main absorption tank at rear of property as well as repair the collapsed section of stormwater pipework at the front of the property. So to repair this sinkhole meant excavation of the existing ground, installation of brand new stormwater pits, installing new PVC piping with Geotec materails.

What steps does a plumber take to repair a sinkhole in Sydney?

Sinkhole repair plumber in Sydney removing old piping under ground

#1 Removal & excavation

Once we review the plans from the engineer we can being the work required to excavate and get access to the collapsed plumbing. Using our excavator we can get into tight spaces to dig plumbing out and also dig the trenches needed for the new pipes to be laid.

This step can take a few hours or a few days depending on the type of site it is and how extensive the plumbing repairs need to be.

Sinkhole repair plumber in Sydney trench ready for new pipes

#2 Trench preparation

Once all the old plumbing is removed and ready to be demolished we will go around and prepare all the trenches so they are ready for the new piping to be installed. These will run to all the required locations and the distance will vary based on the site & where the connecting stormwater lines are.

Sinkhole repair plumber in Sydney digging old piping out

#3 New plumbing and stormwater pit installation

After the ground is prepared our plumbers will then begin laying the new plumbing system and systematically connect it to downpipes etc.

In the case of this sinkhole repair we also installed new stormwater pits to help with improving drainage around the building.

#4 Connect stormwater plumbing to downpipes

Once all the pipes are installed in the ground our plumbers will then go around the property to make sure all the downpipes are connected and ready to send water into the new system.

Sinkhole repair plumber in Sydney downpipes replaced

#5 Clean up & check the installation

The last part of the process is to inspect the property to return everything back to a condition that is safe for people to walk on & ensure everything has been completed.

How much does a sinkhole repair cost in Sydney?

There is absolutely no way to provide a set price for sinkhole repairs in Sydney. Literally impossible because the size of the sinkhole & the underlying damage can vary so much. If a plumber in Sydney offers $195 inc gst repairs for sinkholes, then run a million miles.

It is impossible for any plumber to provide a set price for a repair and possible scope of work that can vary in size, complexity and time required.

For this specific job it took us 3 days to complete the repair work and a similar job would cost between $20,000 and $25,000 including labour and materials. We also provide a 15 year warranty on new PVC piping installations like this one.

Repairing large or deep sinkholes is not a job for the average homeowner. 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 a licensed professional. In many cases sinkholes are fixable only with the help of a professional, such as a plumber, engineer or builder. Also keep in mind that a DIY repair may lead to further issues or even void your home insurance.
Dean Doncevski
Dean Doncevski

Dean is the director of Instaplumb Pty Ltd and manages his team of licensed plumbers in Sydney who can diagnose, repair and take care of any type of plumbing problem you may have at your home or business.

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