The Donnybrook Road Branch Sewer will cater to an ever-expanding urban area in Melbourne’s north. The location of the pipeline has presented a number of challenges for construction, however, Pezzimenti Trenchless has brought more than 40 years of experience and expertise in trenchless technology to the project.
When it’s complete, the Donnybrook Road Branch Sewer will stretch 3km along Donnybrook Road, within a future services corridor, and provide sewerage services to more than 8,000 homes.
The location of the pipeline, which passes through privately and developer-owned properties, presented a number of challenges, including the presence of existing services and structures, depth, as well as cultural heritage and natural values such as native vegetation.
To overcome these issues, the construction of the pipeline relied on open cut excavation and trenchless construction methods. In order to complete the project within the January 2018 to late 2019 timeframe, Yarra Valley Water broke the project into three segments and engaged specialist contractors for each section.
Calling in the experts
Pezzimenti Trenchless and MFJ Constructions were awarded the contract to construct one of the sections, which stretches 1,705m and requires 1,060m of trenchless construction, 645m of open cut construction and the installation of eight maintenance holes.
Pezzimenti Trenchless first made a name for itself in pipeline construction in 1957 when G. Pezzimenti and Sons was contracted to the Melbourne Metropolitan Board of Works. Since then, the company has become the industry leaders in the installation of new sewer, water, storm water and conduits utilising their specially and locally built equipment.
Getting down to work
As part of the project, the company employed its Pezzimenti Lazer-Bore System, which uses vacuum extraction to remove spoil and rock cuttings and can achieve a range of bore diameters. This system ensured a small operational footprint and overcame challenges caused by other works in the area; in some cases the construction zone was reduced to 20-30m. It also ensured that bores were accurately installed.
Pezzimenti Trenchless also overcame the high-strength basalt that it encountered, by using specialist-built rock cutters that were fitted to the microtunnelling head; and the requirement to build deep shafts of up to 15.5m, which it achieved by using an 87-tonne excavator and a smaller one-tonne excavator that was fitted with a hydraulic hammer and lowered into the shaft. Groundwater was also an issue, but this was overcome by drilling upstream and using some of the industry’s most powerful vacuums.
Keeping it local
Pezzimenti Trenchless’s extensive local workshop facility provided back-up support to the project and ensured that repairs and modifications to the equipment could be completed without any delays to the project. This has contributed to the project being on target to be completed in September 2019.
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