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As Melbourne’s population continues to grow, maintaining and upgrading essential infrastructure is a must. More than 5 million people already live in the city, which means sewerage systems need to be able to handle a staggering amount of waste.

The Hobsons Bay Main Sewer is responsible for 30 per cent of Melbourne’s wastewater, by transporting it to the Western Treatment Plant. The sewer main was constructed in the 1960s, and is quickly approaching the end of its service life.

As such, the Hobsons Bay Main is sorely in need of an upgrade and will need to be cut off while works are underway, but the needs of Melbourne’s waste network can’t be put on hold so easily. To ensure everything keeps flowing smoothly, Melbourne Water is funding a $206 million duplication project to reproduce the sewer, which will support the network while the original main is upgraded to modern standards.

Early works for the project began in 2021 and construction is expected to be completed in mid-2024. Tunnelling works began in August of 2023, with Melbourne Water’s tunnel boring machine – named Lucey – operating at depths of between 24.5m and 27m below the surface of the Yarra, alongside the original sewer main.

The new 670m Hobsons Bay Main Sewer will stretch from Westgate Park, Port Melbourne to Scienceworks in Spotswood, under the Yarra River. Melbourne Water’s Managing Director, Dr. Nerina Di Lorenzo, said that this major project forms part of a broader Melbourne Water capital infrastructure program that will enhance the reliability of the city’s sewerage network and services for the benefit of Melburnians today and for generations to come.

A collaborative effort

The extensive project is a joint effort between the Victorian Government, Melbourne Water, John Holland and Museums Victoria. Dr. Di Lorenzo said that Melbourne Water is working hard to ensure that business as usual can continue for its neighbours, like Scienceworks and Grazeland, while considering the needs of the community and the impact these works have on everyone.

“We also have a close working relationship with the team at John Holland, who we appointed to construct the duplicate sewer,” Dr. Di Lorenzo said. “Melbourne Water and John Holland project teams have been working on this for three years. We’ve established two working sites at Spotswood and Port Melbourne, constructed four shafts and started tunnelling works.”

James Le, Melbourne Water’s Project Manager overseeing the Hobson Bay Main Sewer duplication, said that collaboration has been central to the company’s approach. “We’ve developed a strong partnership with our delivery partner, John Holland. Our partnership extends over three years on this project, but has been ongoing as our long term partner on the Major Capital Delivery Water Framework,” Mr Le said.

“Our commitment to safety is of utmost importance to both companies. On the ground we hold joint safety forums, and mental health and wellbeing toolboxes, and these serve as a platform where we mutually learn from each other’s experiences, refining our practices for a safer work environment.” John Holland Project Manager, Lucas Martinez, said that John Holland’s long-standing relationship with Melbourne Water spans over 20 years, including multiple tunnelling and deep sewer projects.

“With any project, it’s important to work directly with the client, and in all my experience I have found that open and transparent communication is the key to successful project delivery,” Mr Martinez said. “Working closely together we’ve been able to ensure that our efforts are aligned and that any challenges are addressed collaboratively.

This partnership approach has not only helped us better understand the project’s goals but has also allowed us to find innovative solutions together, some of which resulted in securing significant financial wins for the client and project.

“As a result of our collaboration, we’re now about to expand our scope of works to include an upgrade of the North Drop Structure and being engaged for Early Contractor Engagement works to provide an optimal solution to the surrounding sewer assets that require rehabilitation. “This approach allows Melbourne Water to maximise the efficiencies of having John Holland already mobilised onsite and tapping into the knowledge and experience of the team.”

Community engagement

Dr. Di Lorenzo highlighted the engagement with the local Spotswood Primary School, which selected the name ‘Lucey’ for the tunnel boring machine. “Lucey is named after Lucey Alford, the first female Bacteriologist and the first woman employed by the Melbourne Metropolitan Board of Works (now known as Melbourne Water) as a scientist at the Spotswood Pumping Station.

“We’re also working with Westgate Biodiversity and Parks Victoria – as part of our Construction Environmental Management plan – to ensure we’re looking after the flora and fauna around the construction sites. “We couldn’t successfully deliver the project without strong partnerships.”

Mr Le said that community engagement has been a key priority for the company. “Regular collaboration meetings, open communication channels, and a shared commitment to project success have facilitated smooth coordination,” Mr Le said.

“We’ve teamed up with Scienceworks to inspire young minds about tunnelling works, engaged a local primary school to involve the community, and partnered with the West Gate Biodiversity Group to enrich local ecosystems. “These collaborations go beyond construction, fostering a community-driven and environmentally conscious approach to the Hobsons Bay Main project’s success.”

MICHELLE NATION (GENERAL MANAGER, JOHN HOLLAND), WATER MINISTER HARRIET SHING, LOCAL MEMBER FOR WILLIAMSTOWN MELLISSA HORNE, LOCAL MEMBER FOR ALBERT PARK NINA TAYLOR, DR, NERINA DI LORENZO (MELBOURNE WATER) AND JONATHAN SHEARER (GENERAL MANAGER, SCIENCEWORKS/MUSEUMS VICTORIA), IN FRONT OF LUCEY THE HOBSONS BAY TUNNEL BORING MACHINE

A net zero carbon footprint

Dr. Di Lorenzo said that Melbourne Water is aiming for net zero carbon emissions on the project, which will be achieved via a number of initiatives. “The project has an integrated sustainable design to reduce carbon. For example, we’ve been able to reduce carbon emissions by decreasing the amount of concrete needed.

“We installed a solar energy system consisting of 250 panels and batteries that will power our construction site sheds – which traditionally would have been diesel powered. Further, this solar infrastructure can be packed up and used on other Melbourne Water projects, which is exciting from an environmental perspective.

Dr. Di Lorenzo said that electric vehicles are also being used to travel between work sites and rainwater tanks on both site compounds are reducing potable water usage. “We’re also reusing and recycling everything we can, like soil which is being diverted away from landfill, and we even have an edible garden on site supported with composting. The environment is a major consideration for us.”

Mr Martinez said that he is incredibly proud of John Holland and Melbourne Water’s commitment to sustainability. “Building infrastructure isn’t just about concrete and steel, for us, it is about ensuring a better and greener future for generations to come. “We have embedded sustainability into the core of this project with a commitment to achieving net zero, including solar power, sustainable concrete, alternative materials with reduced footprint, an electrical site vehicle and a comprehensive soil management program.

“We are very close to reaching carbon neutrality. This will be achieved by embedding sustainability in everyday operations and all decisions made by the whole team. “This has enabled us to reduce the footprint by approximately 30 per cent from the original design, and we are currently working with the most reputable climate consultants and Melbourne Water to secure the most reliable and traceable carbon offsets offered by the industry.”

A unique and challenging project

“It’s not every day that we tunnel under the Yarra River,” Mr Le said. “The fact that we’re leaving behind a significant legacy that improves Melbourne’s sewerage infrastructure for generations to come is definitely worth getting out of bed for. Mr Le said that the technical challenges associated with deep sewer construction need to be carefully considered and the complexity of working within a historically and culturally significant area makes every day interesting and enjoyable.

“This project has presented diverse challenges, each met with a strategic response. We’ve encountered the unexpected discovery of a culturally significant artifact during excavation, demanding careful preservation. “Additionally, international procurement quarantine delays have required adaptive scheduling and resource management.

Working around critical underground services throughout the construction period necessitated meticulous coordination and phased execution. “These challenges highlight the complexity of the project, but through collaborative solutions and agile planning, we’re able to successfully work through them.” Mr Martinez said each project delivers its own set of challenges which is part of what he loves about the industry.

“While John Holland has a history of delivering diverse infrastructure projects, this one stands out due to its highly technical nature, high-risk profile and demanding scope of works and our commitment to achieving net zero emissions,” Mr Martinez said. “My experience has predominantly centred around the water industry. However, this project affords me the opportunity to apply my expertise within a different context and do so with a range of sustainability initiatives including solar energy, sustainable concrete and soil management.

“Along with the complexities of tunnelling under the Yarra River and coordinating with project stakeholders, these sustainable measures set this project apart, reflecting our commitment to environmental responsibility and challenging the status quo. “This project has also delivered a number of successful social value initiatives – well beyond anything I have delivered in the past – as well as effectively achieving gender parity within the project team.”

Mr Martinez said that within a highly complex and challenging project, tunnelling works are the highest risk phase across the two-year construction. “Challenges to date have included complex ground conditions, including shaft excavation and tunnelling through seven distinct geologies from soft silt to hard basalt, ground improvement works at our Port Melbourne site (east of the Yarra River), working within a live sewer environment and in addition, we are doing all of this within the footprint of a fully operational children’s science museum with over 500,000 visitors annually.

“Our net zero emissions target has also pushed us to find innovative ways to prioritise sustainability. “We’ve worked to address challenges from the commencement of the project, from finding the right tunnel alignment and technical solution at tender time to secure the project, through recruiting and retaining top talent in an extremely competitive market, to managing and mitigating delays from international shipping delays in the post-COVID supply chain landscape.”

A lasting upgrade for Melbourne

Mr Martinez explained that once the tunnelling is completed, the John Holland team will proceed with the live connections to the existing sewers and the permanent works. “The live connections will involve working in the existing Hobsons Bay Main Sewer under live flows, which requires very detailed and careful planning in order to make sure there are no impacts to the existing sewer network and ensure the safety of everyone involved.”

Mr Martinez said that being a live asset, it’s critical to work in close collaboration with Melbourne Water Operations to ensure all their constraints and requirements are met. “The permanent work will involve the installation of the maintenance structures which will provide Melbourne Water with access to the new asset once in operation, as well as the mechanical works (penstocks, stopboards), electrical and control scopes (power supply, instrumentation, CCTV) which will provide the asset with the required functionality to ensure safe and reliable operation for many years to come.”

Dr. Di Lorenzo said that Melbourne Water invests hundreds of millions of dollars per year into a wide range of critical infrastructure projects.

“The Hobsons Bay main sewer duplication project is a great example of the work that we are doing in this space for Melburnians. “We’re looking towards the future and anticipating the evolving needs of a growing Melbourne. “This project ensures our infrastructure is keeping up with future demand.

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