From the magazine, Microtunnelling, Pipe jacking, Tunnelling

Jacking under pressure

The Melbourne Main Sewer Replacement (MMSR) is an essential infrastructure project being delivered on behalf of Melbourne Water. The project will replace the existing 110-year old sewer, providing health and environmental benefits and increasing capacity to service Melbourne’s growing population.

One of the project’s many technical challenges was to develop a way to bypass the existing high-volume infrastructure while connecting it to the new system.

To accomplish this, the project team from Melbourne Water, John Holland, GHD and Aurecon developed a solution to create a bypass line that would safely handle the high volumes of Melbourne’s existing main sewer while establishing a long term vent between the two systems. This was achieved using a HOBAS DN600 pressure jacking pipe.

In an Australian first, the HOBAS pressure jacking pipe was installed along with the relevant joints and fittings. Due to the pipe’s innovative design, no additional pressure pipes were required to be installed within the jacked line, creating an economical solution for the MMSR project.

Because the vent will carry exhaust fumes containing corrosive gasses that are known to damage traditional pipe materials, such as concrete and steel, the HOBAS pipe was a suitable choice due to its corrosion-resistant properties and the pressure criteria.

The benefits of pipe jacking are widely documented across the globe, and HOBAS’ Australian-first case study for the MMSR provides a prime example of how to implement best practice in trenchless installation on Australian shores.

John Holland MMSR Site Manager Roger Soso said the DN600 CC-GRP Pipe was chosen for its cost-effective installation and its ability to satisfy all of the project requirements with a single pipe solution.

“As the vent pipe was required to carry corrosive gasses, concrete and steel piping were not suitable materials in this instance.

“The HOBAS pipe product suited the requirements and application of the project, and we were able to use it for the vent pipe installation and also as a bypass while the existing infrastructure was upgraded.”

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