Golder Celebrates the Opening of Sydney’s WestConnex M8

Leading global engineering and consulting firm Golder celebrated the opening of the new WestConnex M8 in July in Sydney, Australia. The project is part of the largest and most complex multi-disciplinary transport infrastructure project in Australia.

With Sydney experiencing rapid population growth, increasing road congestion, and transport challenges, road improvements were urgently needed for quicker, safer and more reliable travel. The WestConnex M8, connecting Kingsgrove to a new interchange at St Peters, is expected to reduce congestion and halve the duration of a peak-hour trip into the city.

The large-scale project is unique and multifaceted, with two new 9 km road tunnels and a multi-level road interchange constructed over a historical industrial landfill. Golder was involved throughout the design and construction process of the project supporting client CPB Dragados Samsung Joint Venture, who were responsible for construction of the project on behalf of the asset owner/ operator, WestConnex | Transurban. The firm’s wide-ranging involvement and cross-discipline interaction for over six years spanned geotechnical, contamination, water and waste management, as well as design and construction aspects.

“We are proud that our multi-disciplinary expertise has supported our client to safely and successfully complete as large and intricate a project as the WestConnex M8, which is a critical element in building a modern transport network across Sydney,” said Craig Curnow, Golder’s Regional Leader for New South Wales.

“Leveraging the technical excellence of our national and international experts, we have focused on solutions to drive the design and construction program, reducing risks and adding value to the project across an extensive range of activities,” said Curnow.

Thriving on challenges

To assess the ground conditions, Golder conducted extensive geotechnical, hydrogeological and contamination site investigations across more than 500 locations, at depths up to 90 m. The landfill investigation was particularly challenging, requiring penetration through as much as 40 m of historical municipal and construction waste.

“We modelled the results of the investigations and advised our construction and design partners of the implications for design and construction,” explained Golder’s Project Manager Tristan McWilliam. “In addition, our team designed and installed instrumentation for ongoing monitoring.”

“Due to the complex ground conditions, particularly over the landfill, we mitigated risk, working with our design partners Aurecon and Jacobs, to improve the foundations and earthworks, as well as cost-effective use of controlled modulus columns, rapid-impact compaction and surcharging.”

During construction, Golder continually reviewed ground conditions in the tunnel and surface excavations and designed and supervised temporary works (e.g. earthworks, foundations, retention systems, crane and piling platforms).

Sustainable solutions

An important sustainability goal was the incorporation of the historical landfill into the landform of the St Peters Interchange with minimal haulage of excavated materials and waste away from the site.

Golder worked with the project team to identify options to reduce waste and reuse clean tunnel spoil and excavated material for pre-load embankments, temporary works platforms and general earthworks.

The firm’s landfill specialists designed steep, reinforced batters to house existing contaminated material onsite. They also designed the capping system necessary for eventual closure of the landfill – including monitoring systems, geosynthetics, leachate drainage and treatment, and gas capture.

“As well as easing congestion for motorists along the M5 East corridor, this project resolves a landfill and waste challenge, and brings new green spaces and facilities to the community,” added McWilliam.

Golder continues to be involved in the broader WestConnex project, providing consulting services to the adjacent M4-M5 Link project, due for completion in 2023. The firm has more than 850 employees in Australia and New Zealand thriving on challenges across a range of nation-building projects. In addition to WestConnex in New South Wales, other transport infrastructure projects include Suburban Rail Link in Victoria, Inland Rail and Brisbane Airport in Queensland, METRONET in Western Australia – and many more.

Learn more about Golder’s role in the WestConnex M8 project here.