Western Harbour Tunnel, Sydney, NSW, Australia
Aurecon is transforming Sydney Harbour, replacing dredging with TBM tunnel engineering to deliver a faster, safer and more sustainable second harbour crossing.
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In March 2024, the GEMCO (Milner Bay) Wharf was severely damaged, halting global exports of manganese ore, used in steelmaking and rechargeable batteries. As the world’s largest exporter of manganese ore, responsible for 10-15 per cent of global supply, expediting the recovery of the wharf was an urgent priority.
The wharf is also critical for its fuel import to Groote Eylandt – fuel that is used for all vehicles, plant, and electricity generation – adding to the imperative to return it to operation as rapidly as possible.
GEMCO appointed Aurecon to lead planning and design of the recovery effort. Drawing on deep expertise in marine infrastructure, multidisciplinary engineering, and disaster recovery. Aurecon enabled manganese exports to recommence in May 2025, transforming the facility from catastrophe to rebuilt and operational in just 14 months – a process that could have taken three to five years.
Aurecon’s scope covered every phase of the recovery, from damage assessment and environmental planning to full multidisciplinary design, construction support, and commissioning. We worked across maritime, structural, geotechnical, electrical, mechanical, fire protection, process safety and cathodic protection disciplines.
“This was a completely different approach to delivering a project, and it shows what’s possible when schedule is at the absolute forefront.”
Arne Nilsen, Design Director, Aurecon
With time the ultimate driver, Aurecon collaborated to develop cost-effective design solutions aligned with the client’s brief to minimise schedule and ensure efficient, rapid delivery within site constraints.
A technically complex project, the team’s initial priority was making the site safe: stabilising what could be saved, planning how to safely demolish what couldn’t, and determining the fastest path to restore operability.
Aurecon’s strategy for expedited recovery relied on reuse of the existing offshore electrical substation and shiploader. Both essential for operations, they were precariously supported upon severely damaged structures that required careful staging of stabilisation and demolition works. Extensive pre-construction works included securing the damaged shiploader, demolishing non-salvageable infrastructure, and conducting structural analysis of salvageable components.
A system of temporary works was developed to be safely installed from above to support the shiploader and substation, avoiding the need to work beneath structures of unknown integrity. Carefully determining what parts of the remaining structure could be relied upon to support this temporary works was key to the success of this strategy. This innovation saved many months of reconstruction.
Integral to rapid recovery was Aurecon’s design for the piles supporting the wharf. With over 100 piles destroyed, Aurecon decided the most reliable programme response for the new piling would be to minimise geotechnical risk, minimise the number of new piles, and to design around the large areas of seabed that had to be avoided because of the original piles’ locations.
Embracing a 21st century view to the design, just 28 new piles replaced the original 100. The new piles were larger and arranged in some unconventional configurations due to the original piles’ positions. This not only minimised disruption to the seabed but significantly accelerated reconstruction.
Also, a highly modular replacement structure was developed to facilitate rapid construction, with prefabricated components that could be quickly assembled onsite. The modularity of the structures was closely coordinated with the fabrication and construction teams to minimise site work and ensure equipment was readily available.
These smart build strategies reduced labour hours and allowed work to continue flexibly and responsively, even as designs evolved daily.
The project has won the following award:
Aurecon is transforming Sydney Harbour, replacing dredging with TBM tunnel engineering to deliver a faster, safer and more sustainable second harbour crossing.
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