Pezzimenti Trenchless has recently completed a challenging sewer diversion project in the heart of Melbourne city.
Pezzimenti Trenchless undertook a complex sewer diversion project at the Arts Centre in Southbank, Melbourne. The project was initiated by Harris Civil Pty Ltd, who were engaged by Lend Lease to oversee construction for the Arts Centre’s expansion.
The project officially began in April 2024, with a completion date of December 2024. Pezzimenti Trenchless was responsible for the installation of new sewer infrastructure using its advanced laser-guided microtunnelling system.
The project required Pezzimenti Trenchless to work closely with Harris Civil, who handled additional site works such as constructing launch and retrieval pits, supplying the pipes, managing traffic flow, building manholes, and performing necessary rectification works. Harris Civil also managed the connection to the existing sewer network.
A key challenge on this project was the need to vacate the site periodically for up to four weeks at a time to allow Harris Civil to build maintenance holes and complete other roadworks, adding a layer of complexity to the project timeline.
Despite these interruptions, Pezzimenti Trenchless was able to successfully carry out the essential trenchless operations without delay.
The scope of the project involved the installation of two large diameter Amiblu GRP jacking pipes – one with an outer diameter of 324mm and the other with 427mm.
In total, approximately 700m of microtunnelling was required, with installation depths varying between 4m and 6m.
The microtunnelling work was particularly critical in ensuring the efficient and safe diversion of the sewer line while keeping disruptions to the surrounding community to a minimum.
The project site presented significant challenges, especially the ground conditions, which consisted of Coode Island silt.
This type of silt is known for being unstable, prone to swelling, and not self-supporting, which can complicate traditional excavation techniques.
These conditions made trenchless methods, particularly Pezzimenti Trenchless’ laser-guided pipe jacking system, the ideal solution.
The system allowed for continuous ground support by installing the pipes directly behind the drill head, effectively stabilising the ground as the tunnelling progressed.
In addition to the challenging ground conditions, Pezzimenti Trenchless faced the added difficulty of managing groundwater.
Given the proximity to the Yarra River and the general instability of the silt, groundwater management was required around the clock to ensure a safe and effective work environment.
With the Arts Centre and Southbank Boulevard being high-traffic areas, traffic management was a critical element of the project.
Harris Civil took charge of ensuring traffic continued to flow smoothly around the construction site, which was paramount to the success of the project.
The team had to coordinate lane closures, detours, and other traffic measures to avoid disruption to local businesses, residents, and visitors to the Arts Centre.
One of the most notable achievements of the project was Pezzimenti Trenchless’s innovative solution for the retrieval of the microtunnelling head.
Due to space constraints and site restrictions, Harris Civil was unable to excavate the necessary three retrieval shafts to pull back the bore head. In response, Pezzimenti Trenchless developed a unique method to extract the bore head through the installed GRP jacking pipe itself. This innovation saved considerable time and resources while also adhering to the site’s limitations.
Trenchless technology was the only viable method for completing this project due to the combination of traffic restrictions, the need to drill under and along existing roads, and the challenging ground conditions at depth.
By utilising advanced microtunnelling techniques, Pezzimenti Trenchless was able to complete the project without the need for large-scale surface excavation, minimising disruption to the local area.
Pezzimenti Trenchless’s ability to deliver successful outcomes in such a challenging environment is a testament to the its expertise and commitment to innovation. Since its founding in 1957, the company has positioned itself at the forefront of the trenchless industry through its laser-guided microtunnelling system.
Director Joe Pezzimenti said the project was a testament to the use of trenchless methods in high traffic areas.
“It’s a perfect example of how trenchless methods can be used to overcome significant challenges, such as difficult ground conditions and the need to minimise disruption in urban areas,” he said.
“We are proud of the work we have done here and look forward to continuing to provide innovative solutions for complex projects.”
With the successful completion of the Arts Centre Sewer Diversion, Pezzimenti Trenchless continues to solidify its position as a leader in the trenchless construction industry, with a focus on safety, efficiency, and environmental sustainability.
For more information, visit pezztrenchless.com.au
This article was featured in the April edition of Trenchless Australasia.
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