The Barangaroo site is a major extension to the Central Business District (CBD) of Sydney, and represents an increase of over 15 % in the size of the CBD. The southern portion of the Barangaroo site has been developed into three main office towers and several low-rise residential/office blocks, linked together with podiums and a common three-level basement. The approximately 1,000 bored piles were designed to carry the building loads through rock shaft friction and end bearing. Groups of piles were designed beneath the raft cores with “mega piles” supporting the main tower columns carrying up to 10,000t each.

The site had a number of challenges required to be overcome. The historic industrial nature of the site meant that there was the presence of hazardous materials including asbestos in a number of areas. Piles in these areas were installed in designated contaminated zones, requiring specialist personal protective equipment.

The 2.4m diameter “mega piles” carrying the main tower columns were installed under bentonite with a short temporary top casing. To improve drilling stability through the fill material the pile locations had been pre-treated with a bentonite-cement-silicate grout prior to pile excavation.