With freight container volumes predicted to triple in the next 30 years, and vessel capacity and size continuing to increase at pace, Australia’s major logistics infrastructure must remain ready to meet impending challenges without congestion. Sydney’s Port Botany container port is one of Australia's largest and is a critical part of the logistics chain for New South Wales. The original Port Botany facility opened in 1979, but a major expansion project to manage increasing demand was conducted between 2007 and 2012, adding a third container terminal and accommodating a greater number and size of ships. The AU$1 billion project was designed to provide significant extra capacity to meet projected long-term trade growth.
Golder provided geotechnical services for the design and construction of the Port Botany Expansion (PBE) - an infrastructure project on a massive, once-in-a-generation scale.
To create a third terminal, 60 hectares of land was reclaimed, with dredging of approximately 11 million cubic metres of material. Strong, stable foundations needed to be created to support the placement of more than 215 concrete counterfort units weighing 640 tonnes each. These units, created on site, formed a 1850 metre long, 21.5 metre high wall to accommodate five new shipping berths. The PBE extension and upgrade works also included new revetment edge structures, bridges, roadways, pedestrian and cycle paths, lookouts, boat ramp and amenities, as well as upgrades to the beach profile and shallow estuarine habitat for migratory shore birds.
Creating a safe, stable terminal on reclaimed land
Golder’s design team developed solutions to complex stability and serviceability challenges for the project. Understanding the geotechnical issues and risks on the site was essential, given the volume of dredging and reclamation and the scale and importance of new berth structures. Our expertise in managing geotechnical risk and quantitative risk assessment helped our client make informed decisions.
To improve confidence that the new works would be fit for purpose, we benchmarked the design of new works against historical performance of the original port structures and reclamation. This back analysis helped derive design parameters for the new port, in combination with geotechnical sampling and testing.
Dredging, backfilling and compaction commenced in 2008. Dredging was necessary to deepen the port for container vessel access, provide materials for the reclamation, create a new recreational boating channel and prepare for installing the counterfort wall units. Golder designed the reclamations and ground improvement, bringing innovative and practical solutions to soil-structure design and compaction, including onsite research into the influence of vibrocompaction on structures. This helped to reduce the risk of locking-in high earth pressure and wall stresses that could potentially lead to cracking of concrete wall panels.
We also conducted the detailed geotechnical design for the large blockwork and counterfort retaining structures. By tailoring the structural wall design for site-specific earth pressures, we were able to optimise the design to save time and materials, minimising the weight of the units and reducing the number of units to be placed by a third. Further efficiencies were achieved by casting the counterfort units onsite in a seamless production line. The units were carefully designed for a 100-year life in a high-exposure environment, including a 1/1000year aggregate exceedance probability (AEP) earthquake event.
Throughout construction, our team provided ongoing and responsive geotechnical advice, including monitoring, and providing behavioural recommendations relating to structural movements and forces. This increased confidence and safety and enabled the design to be optimised to reduce unnecessary time and cost. For example, monitoring data indicated that preload durations (the time during which an area is subjected to loading to minimise post-construction settlements) could be safely reduced. Our extensive monitoring program also indicated that earth pressures agreed well with design predictions, which provided our client with confidence in the modelled behaviour of the counterfort structures and surface infrastructure.
We completed our work on the design and construction of the PBE project on time and on budget. Since then, we have continued to provide services to support the port’s long-term performance. We have also undertaken geotechnical investigations, analysis and reporting for the NSW Ports Master Plan, including a rail capacity upgrade.
Port Botany’s third container terminal commenced operations in 2013 and was officially opened in 2014. The project provides significant long-term economic, environmental, and social benefits for the local community and the people of NSW. Today, around 1600 ships carrying over 2.5 million containers pass through Port Botany each year to support the largest population centre in the country.
The Port Botany Expansion project won ‘highly commended’ in the global Ground Engineering Awards in 2011.