When Auckland’s Orakei Main Sewer collapsed in September 2023, Watercare Services called on civil engineering company March Cato to respond.As one of the major city’s main sewer transmission lines, the task of repairing the pipeline demanded speed, precision and lasting quality.
And for that, March Cato and Watercare turned to Channeline.
Since the 1980s, Channeline has provided bespoke structural glass reinforced plastic (GRP) lining systems.
Channeline’s GRP solution is a fully structural rehabilitation solution for the trenchless rehabilitation of sewers, tunnels, culverts, stormwater and other buried structures. Its strength lies in its versatility and customisation, which is what made it a perfect fit for the Orakei Main Sewer Project.
To carry out the rehabilitation works, March Cato designed a custom 35-tonne reinforced workstation, which was lowered by crane over the location of the collapse.
Here, March Cato was able to clear the debris in the sewer, and then begin to rehabilitate 120m of sewer. This was done in two drives both upstream and downstream of the breach.
The sewer was a unique egg shape with a 2.3m by 1.5m diameter, which is where Channeline’s custom GRP lining truly shone.
“It was a totally bespoke solution that Channeline provided to us,” March Cato Project Manager Daniel Cato told Trenchless Australasia.
“That’s the beauty of Channeline liners – they were made to a custom profile with a very quick turnaround.”
Channeline can custom design and manufacture fully-structural lining systems in any shape and any size, making it an ideal partner for any contracting company working in the civil infrastructure space.
“The company was great to deal with, coaching us through the installation process and providing an on-site expert,” Cato said.
“The liners mated together nicely, and we were able to successfully line the sewer in live flow.”
Many trenchless operations take place in urban areas where space is limited. Indeed, the Orakei Main Sewer Project was no exception. This is where the lightweight construction of Channeline lining played a key role.
“One major benefit of using Channeline lining is that they are considerably lighter than typical liners,” Cato said.
“This meant we were able to use a smaller crane to lower these components down into the workspace.”
Despite the light weight, Channeline GRP lining sacrifices nothing in strength, and can return even the most heavily used pipelines to serviceability for many decades.
The first two layers of Channeline GRP lining, which are the surface and barrier layers, incorporate a corrosion barrier. This is manufactured from high-grade surface veil, precisely impregnated with resin, followed by several layers of multi-axial engineered fabric and glass fibres.
The next layer is a central core, composed of sand and resin, which is evenly applied to the exact thickness required.
The following layers are formed using multi-axial fabric, glass fibres and resin.
This outer surface is treated with a bonded aggregate to enhance adhesion to the annular grout.
All of this comes together to form a strong lining system that is resistant to chemicals, corrosion, UV and extreme temperatures.
With the successful repair of this 120m section of the Orakei Main Sewer, Watercare and March Cato now turn their attention to the subsequent stages of the renewal works, which includes a significant 720m drive.
Once again, the company will combine its engineering know-how with Channeline’s unique and versatile lining solution.
For more information, visit channeline.com
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