Barangaroo South harbourside basement, Australia, challenges and solutions

At Barangaroo South on Sydney's central business district waterfront, Australia, Lend Lease is working with the New South Wales government on the A$6 billion (£4 billion) transformation of a former container port into a thriving business, residential and leisure precinct. The vision is that Barangaroo South will enhance Sydney's position as an internationally appealing, globally competitive, environmentally sustainable city. The development will be Australia's first large-scale carbon dioxide neutral precinct. Barangaroo South will feature three commercial towers ranging in height from 39 to 49 storeys, sharing a common, two-level basement to be retained around its perimeter by an approximately 770 m long diaphragm wall, socketed into Sydney sandstone. As the basement excavation will be below sea level, it is essential that the site retention wall for the basement also acts as a cut-off against groundwater ingress. This paper provides an overview of the design and construction challenges facing the installation of the diaphragm wall and the innovative solutions adopted to overcome these challenges.