Functional design and early investigative works
The Western Trunk Sewer, which runs from Brooklyn Pumping Station to the Western Treatment Plant in Werribee is 4.5 metres in diameter. It plays an important role in our sewer network, carrying over 57% of Melbourne’s wastewater for treatment in Werribee.
Why is this important?
The trunk sewer consists of 15.2 kilometres of deep tunnel from Brooklyn Pumping Station to Hoppers Crossing Pumping Station, and 7.2 kilometres of shallow tunnel from Hoppers Crossing Pumping Station to the Western Treatment Plant. It was constructed in the late 1980s and our regular inspection program has identified some sections coming to the end of their working life. That’s why at Melbourne Water, we will be relining the sewer to ensure a safe sewerage service for local homes and businesses today, tomorrow and for generations to come.
What's happening?
We will be relining 4.4 kms of the shallow tunnel between Hoppers Crossing Pumping Station to the Western Treatment Plant using a trenchless rehabilitation method. 14 maintenance holes will also be rehabilitated.
Project Timeline
Upgrading a sewer this size, while it is in use, is complex. We are currently completing preliminary investigation works to explore the best options for the sewer’s rehabilitation. The investigation results will ensure the sewer is upgraded efficiently and safely while minimising the impacts to the community as much as possible.
Now - Mid 2024
Late 2024 to Mid 2025
Tender and project award
Mid 2025 to Early 2026
Detailed design
Early 2026 - Mid 2027
Procurement and mobilisation
Mid 2027 to Late 2029
Sewer relining and maintenance hole rehabilitation
Late 2029 for Early 2030
Reinstatement
Project Completion
Early 2030
What to expect
Utilising 'trenchless' technology
To upgrade the sewer, we will use one of two trenchless technology technique. These allow us to reline the inside of the existing sewer with new plastic sleeving or pipe without having to dig it up, which has several benefits, including:
- Significantly reducing the impacts on the important cultural and environmental values of the landscape, we are working in.
- Ensuring that disruptions and inconveniences at street level are kept to a minimum, and residents and businesses don’t have to worry about open trenches on their doorsteps.
- Allowing upgrade works to be completed more quickly and efficiently compared to traditional trenching methods.
- Ensuring the structural integrity of the sewer is maintained for decades to come.
Access tracks to maintenance holes
Access tracks for construction vehicles and machinery need to be created to safely and efficiently get to the maintenance holes to complete the works. This may require earthworks in some areas due to the landscape. Some access tracks will remain in place to enable ongoing maintenance activities to be performed safely into the future.
All temporary access tracks will be reinstated and planted over with grasses.
Construction impacts
As a guide, we have listed a number of potential impacts that you may notice during major construction works:
- Night works are required for some of the relining works when sewage flows and traffic flows are at their lowest.
- Noise: There will be a short-term increase in noise in the area, but we will do as much as possible to reduce the construction noise. We will monitor noise and dust levels throughout works to ensure they don’t exceed Environmental Performance Agency thresholds.
- Odour: Some odour is expected when carrying out the works due to harmless gases escaping from the maintenance holes when they are opened. We aim to minimise and localise this as much as possible.
- Traffic, parking, cyclists, and pedestrians: There will be temporary changes to traffic conditions, including lane closures, road closures and parking restrictions. For your safety, work areas will be fenced, restricting access, while work is being completed. We encourage you to follow all directions and take care around work areas.
- Cultural Heritage: Cultural Heritage conservation is an important part of valuing and preserving our traditions and culture. Melbourne Water will comply with the Heritage Act for the delivery of each section of the works and engage with traditional owners throughout the project.
- Environment: To safely access maintenance holes, there will be some instances where trees and vegetation need to be trimmed or removed.
We will make every effort to minimise the impact of these works on the local community and the environment.
Reinstatement of affected areas
After the works are completed, we focussed on reinstating areas affected by our work activities, including re-grassing and re-planting in the local region to rehabilitate disturbed areas. This will be undertaken in accordance with revegetation and reinstatement plans approved by Council and Parks Victoria.
When will we be working?
Works will be undertaken between:
- Night works: 9 pm to 7 am, Sunday to Thursday
- Day works: 7 am to 6 pm, Monday to Friday
- Weekend hours: 9 am to 3 pm Saturdays (if required)
Thank you for your understanding and patience during these essential works.
On occasions, we may need to undertake works out of hours. We will notify you in advance if these works are required. The timings and dates are indicative and subject to change with no prior notice due to weather conditions and fluctuating sewer flows.
Keeping you informed
Before and during construction, we'll provide information in several ways:
- door knocking directly impacted businesses and residents
- bulletins/newsletters in the surrounding area
- community information sessions
- social media
- web page updates
Contact us
For more information, please contact the project team: