Life extension strategy of Brotherson Dock wharf structures

Port Botany hosts New South Wales’ only dedicated container handling facility and services the largest population center in Australia. The Brotherson Dock wharf structures at Port Botany were commissioned in 1979 and features six out of the port’s eleven container berths.

Following the long term leasing of Port Botany to NSW Ports in 2013, it was essential to NSW Ports’ business to understand the capacity and condition of this asset and to ensure its longevity.

Infracorr Consulting was engaged to undertake a detailed condition assessment of the Brotherson Dock wharf structures. The wharf structures consist of a combination of reinforced concrete counterfort units, corner caisson units and capping beams.

Given the complexity of the assets, multiple inspection and testing techniques were performed over two years to determine the condition of the assets. These investigations were designed to complement historical condition assessments done under the previous ownership.

NSW Ports, in consultation with Infracorr Consulting, considered a range of repair and protection methods for the reinforced concrete structures. This life-extension strategy adopts a whole of life approach with an objective of extending the useful life of the wharf structures by another 50 years with minimum disruption to existing terminal operations.

The strategy adopted a novel approach to the protection of concrete structures through design and installation of a combination of water cathodic protection (Water CP) and hybrid corrosion protection (Hybrid CP) systems. The Water CP system provides protection to the structure up to high-tide and the Hybrid CP system provides protection for the structure from mid-tide to the deck of the structure. Full-scale trials were conducted to determine the level of protection that could be achieved by each of the systems and how these would interact in the upper tidal zone.

The system is currently being installed across Brotherson Dock.