Blog | Pipe Doctor

The Challenge: A Mysterious Sinkhole in a Backyard

When a homeowner contacted Pipe Doctor about a recurring drain blockage, they had no idea it was just the surface symptom of a much bigger issue. They had been experiencing ongoing drainage problems, which had been attended to by another contractor, but the issue persisted. Then, the situation escalated—a sinkhole suddenly opened up in the backyard, right in line with the sewer line.

Understandably concerned, the homeowner called us to investigate, mentioning that a similar issue had occurred before and had been backfilled at the time. With the problem reoccurring, it was clear that a more in-depth assessment was needed. Our team immediately mobilised to assess the situation and determine the best course of action.

The Investigation: Identifying the Root Cause

Upon arriving on-site, our team conducted a thorough assessment to determine the cause of the sinkhole. Given its location and the homeowner's history of previous collapses, we suspected a major structural issue within the underground sewer network.

We proceeded with a CCTV drain inspection, navigating through the pipes to uncover the problem. Our suspicions were confirmed—the sewer line had collapsed, causing the ground above to become unstable. Over time, soil had been gradually washed into the broken pipe, creating a void beneath the surface. Eventually, the weakened ground structure gave way, forming the sinkhole.

A collapsed sewer line can cause significant property damage if left unaddressed. The instability of the ground poses safety hazards, potentially leading to further collapses, foundation movement, and costly repairs. In this case, the homeowner was lucky to have caught the issue early, as prolonged neglect could have resulted in an even larger sinkhole and major property damage.

The Solution: Restoring Stability & Functionality

With the issue identified, our team quickly developed a plan to repair the collapsed sewer while minimising excavation risks and ensuring the long-term stability of the property. Given the instability of the ground and the potential risks of working in an open excavation, we opted for a trenchless rehabilitation approach. This method allowed us to restore the sewer line without the need for extensive digging, reducing disruption to the homeowner and maintaining the integrity of the surrounding landscape.

1. Minimal Hydro Excavation to Expose the Damaged Pipe

Instead of traditional excavation, which can further destabilise the surrounding soil, we used hydro excavation to carefully expose the sewer pipe's damaged section. This non-destructive method allowed us to remove soil and debris with precision, ensuring we could access the affected area without causing unnecessary disturbance. Hydro excavation is particularly effective in fragile ground conditions, as it prevents further erosion and minimises the risk of a larger collapse.

By limiting the excavation footprint, we maintained the safety of the property while still gaining the necessary access to carry out a proper assessment and repair.

2. Pipe Rehabilitation Using Advanced Relining Methods

Once the damaged section of the sewer was fully exposed and assessed, we determined that the best long-term solution was trenchless pipe relining rather than a full pipe replacement. This technique allowed us to reinforce the existing pipe by installing a structurally sound, durable liner within the collapsed section.

Using CCTV drain cameras, we carefully mapped the interior of the damaged pipe to ensure precise placement of the liner. The relining process involved inserting a resin-impregnated liner into the sewer and curing it in place, effectively creating a new, seamless pipe within the old structure. This method restored the full functionality of the sewer line while avoiding the risks associated with working in an unstable excavation.

By opting for trenchless relining, we:

✔ Eliminated the need for open-trench excavation, reducing the impact on the property.

✔ Ensured a faster, safer repair process, minimising downtime for the homeowner.

✔ Provided a long-term, durable solution, ensuring the sewer line remains structurally sound and fully functional for years to come.

3. Backfilling with Stabilised Material for Long-Term Ground Stability

Once the pipe rehabilitation was completed, restoring ground stability to prevent further collapses was the next crucial step. We carefully backfilled the sinkhole using a stabilised material, ensuring that the ground remained compact and structurally sound.

Standard soil backfilling can sometimes lead to further subsidence, especially in areas where the ground has already weakened. To prevent this, we used a high-strength, engineered backfill mix designed to:

Support the newly relined pipe and prevent further soil erosion.
Strengthen the surrounding ground to reduce the risk of additional sinkholes.
Promote long-term drainage stability, ensuring water flows properly without undermining the soil.

Proper compaction of the backfill material was essential to prevent voids from reforming over time. Our team ensured that the area was compacted in stages to create a solid, reinforced surface, giving the homeowner confidence that the problem had been permanently resolved.

4. Final CCTV Inspection & Testing for Quality Assurance

After completing the relining and backfilling, we conducted a final CCTV inspection to verify that the sewer line was fully functional and structurally sound. This step was critical in ensuring the following:

✔ The liner was properly installed with no defects.

✔ The pipe had full flow capacity, free from any blockages or obstructions.

✔ The surrounding area was stable, with no signs of movement or further damage.

By proactively monitoring their drainage system, they can prevent future blockages, subsidence, or unexpected failures.

This trenchless repair method allowed us to restore the sewer line efficiently and safely without the risks associated with working inside an unstable excavation. By combining hydro excavation, pipe relining, and engineered backfilling, we ensured that the property remained structurally sound and that the homeowner would not have to deal with the same issue again.

How Homeowners Can Prevent Similar Issues

This case highlights the importance of early intervention and proper diagnosis when it comes to drainage issues. What initially seemed like a simple blockage turned out to be a major structural failure—one that could have led to more severe property damage if left unresolved.

Here are some proactive steps homeowners can take to prevent similar issues:

Pay attention to recurring drainage issues – If you've experienced frequent blockages, slow drains, or unusual ground movement, it's essential to investigate further.
Schedule regular CCTV drain inspections – Routine inspections help identify hidden drainage issues before they become severe, reducing the risk of structural damage.
Look for signs of soil instability – If you notice sinking areas, cracks in pavement, or soil erosion around your property, it could indicate underlying drainage problems.
Act quickly if a sinkhole appears – If a depression or sinkhole forms, seek professional assistance immediately rather than attempting a DIY fix, which may not address the root.

Why Choose Pipe Doctor for Drainage Repairs?

At Pipe Doctor, we specialise in diagnosing and resolving complex drainage issues using industry-leading technology and expertise. Our team is trained to handle everything from routine drain cleaning to major sewer line rehabilitation, ensuring your property remains safe and structurally sound.

Here's what sets us apart:

Advanced CCTV Drain Inspections: Non-invasive technology allows us to assess underground pipes accurately and determine the best course of action.
Trenchless Pipe Rehabilitation: We use innovative relining techniques to restore damaged sewer lines without the need for disruptive excavation.
Preventative Solutions: We provide maintenance recommendations to help homeowners avoid costly repairs in the future.
Reliable & Transparent Service: From the initial assessment to the final repair, we keep our clients informed every step of the way.

Need Expert Drainage Solutions? Contact Pipe Doctor

If you're experiencing drainage issues, unexplained ground movement, or suspect a sewer problem, don't wait until a sinkhole forms. Pipe Doctor's expert team is equipped with state-of-the-art technology to diagnose and resolve drainage issues quickly and efficiently.

📅 Book an Inspection Today – Call us now or request a consultation to ensure your drainage system is safe, stable, and fully functional!

By investing in proactive drain maintenance and seeking expert assistance when needed, homeowners can prevent costly damage and ensure their property remains structurally sound for years to come.

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When you have a drainage disaster, you can count on us to get you back up and running.

“Knock, Knock, Pipe Doctor” 1300 747 337