South East Water is a Victorian Government utility that provides water and wastewater services to 1.5 million people in an area stretching from inner south-east Melbourne to the Mornington Peninsula. To help manage and maintain its vital water infrastructure, South East Water set up a Design and Construct Pipe and Structures Consortium Panel. The Dromana Sewer Rising Main Renewals is one of the contracts that the ZJW Joint Venture (JV), comprised of Zinfra, Jaydo and WSP, delivered for this panel.
Supporting the Community
Situated on the Mornington Peninsula, Dromana has a local population of approximately 6,000 residents. This beachside community is in the heart of the summer holiday strip along the beaches of Port Phillip Bay and experiences peak summer demand. South East Water identified the need for a large-scale renewal of the sewer mains. The proposed works included the urgent renewal of two major sewer mains through the residential and commercial areas of Dromana.
As part of the ZJW JV, WSP delivered the Dromana Sewer Rising Main Renewals project. The challenges included:
- The project’s location in a residential and commercial area
- The sensitive coastal environment with sandy ground and a high water table
- The condition of the ageing infrastructure
The JV overcame these challenges by using innovative design and careful planning. After investigating different design options, a solution was proposed that enabled the existing mains to keep operating during construction and minimised the impacts on busy streets, such as Gibson Street. In addition, the trenchless construction approach used addressed some of the dangers of excavating in sandy soils, and a tight construction schedule minimised the necessary network shutdowns.
Services delivered included:
- Design of the rising main renewals
- Coordination and collaboration with South East Water, the local authorities and stakeholders to gain approval and acceptance of the proposed works
- 620 metres of 280mm HDPE pipeline that was slip-line installed from within the existing sewer main, by pushing the new pipe in from the ends
- 1.4 kilometres of 450mm HDPE pipeline installed using Horizontal Direction Drilling technology
- 800 metres of 300/375mm PVC pipeline installed via open-cut construction through residential streets
- 250 metres of 300mm PVC gravity pipeline, installed via open-cut construction
- Trenchless construction of the Nepean Highway crossing
- Upgrade works to three pump stations at Masons Avenue, Charles Street and Beach Street
- Bypass works to divert and control enormous flows during shutdowns of the network
- Tie-ins of the new pipelines during restricted and night-time shutdowns of the network
- Construction of the new outlet structure at the confluence of the renewed pipelines at Gibson Street
- Construction of the outlet structure on the realigned Mason Avenue main, which changed from a pressure to a gravity mains
- Reinstatement of the residential roads following construction
- Testing, commissioning and handover
Effective Project Management
Although the JV’s innovative solution required added preliminary planning, ultimately it resulted in a streamlined construction approach and a better end-product for the customer. Combined with the team’s effective project management, the design achieved significant capital expenditure savings.
By reducing the project’s construction footprint, the impacts on the community, the environment and the peak holiday season were reduced. Overall, the Dromana Sewer Rising Main Renewals project has increased the reliability and security of the wastewater system, particularly during the busy summer period.