Pipe Dive – Manly, Sept 2021 

This month, we were called to investigate, diagnose and ultimately repair the troublesome sewer system using a combination of pipe relining techniques at a complex of townhouses situated close to the lovely, Little Manly beach.

The tenants of this split level complex had been experiencing recurring blockages for some time and were in search of a long term solution that didn’t cost, or move the earth – as avoiding excavation was essential due to the intricate, heavily landscaped common areas. 

Tree roots had infiltrated the pipe system and were creating blockages at multiple sections of the sewer line. More critically, escaped wastewater had caused significant ground movement causing further issues for the plumbing system, impacting the structural integrity of the surrounding area. 

Following our investigation, we identified a total of 25m of sewer line that had to be repaired, spanning across 3 levels from a trapdoor to the boundary tap and Sydney Water’s connection. Due to the heavily landscaped area, access was extremely limited. This, in addition to the split-level nature of the property, meant that we had to split the reline into 3 phases, from top to bottom. 

To increase efficiency and reduce cost while ensuring the long-term health of the sewer line, we crafted a solution that involved two crews using multiple pipe relining techniques simultaneously. 

Using a combination of hi-tech inversion and traditional pull-in-place pipe relining, the teams were able to complete the job in less than two days with very little disturbance, ensuring this beachside community could enjoy the best of summer without having to worry about their sewer.

But why did you use both pull-in-place and inversion relining techniques? 

When used correctly, different relining methods have unique benefits. This project required us to reline a considerable length of pipe, over 25m, but also required intricate and precise execution due to a series of junctions and level changes. This is why we combined the straight-line power and efficiency of inversion relining, with the high level of control and precision it allows.

Below is a little more about each method, so you can really start to understand what is going on down below. 

The Pull-in-Place Method

drain during relining process

The pull in place method can be thought of as the most traditional of the relining methods and as such, requires much less equipment to execute than more modern relining methods.

As per the name, it is executed by saturating a tube with EPOXY Resin and pulling it in place, relining the section of the damaged pipe. The nature of the process allows for excellent control and precision in more complex pipelines that may include multiple traps, bends or junctions.

Typically pull-in-place relining requires two access points to the damaged pipeline, enabling the tube to be inserted from one and pulled-in-place from the other. This may be a consideration depending on access and the total length of the pipe to be reined. 

Due to its more analogue nature, this method can take a little longer to execute, however it is very much the preferred method for intricate relining projects and often used in tandem with other methods.

The Inversion Method

new pipes

The Inversion Method requires a more substantial investment in specialised equipment than pull-in-place. However, this does not necessarily mean it is more expensive, but that it is utilised in different ways to solve different problems.

As opposed to pulling the new pipe in place, inversion relining utilises an inversion drum to feed the resin-saturated tube into the damaged pipe whilst turning it inside out, therefore inverting it within the structure of the old pipe and restoring its integrity. With enough air capacity, virtually any length of pipe can be relined.

Inversion relining can be conducted from a single opening, simply shooting the new pipe to a stopping point either side of the damaged pipe. It is also a quicker method of relining, meaning that for long stretches of regular pipeline, inversion is typically economical and preferred to pull-in-place. 

However, when relining more complex pipelines, it can cause issues and require extra work meaning more time and potential costs.

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