Restoring a maritime structure at the largest naval base in Australia

Prior to a planned wharf extension, the Department of Defence required a full restoration of Parkes Wharf at HMAS Stirling, the largest naval base in Australia. This maritime structure, which berths both Navy ships and submarines, was suffering from corrosion and concrete cracking across the entire wharf deck and service tunnels.

As expected, in the 50 years since its construction many features of the wharf required attention. In order to complete a full restoration, the project required remediation of the concrete, new encasement of the 260 piles which support the wharf, servicing of fender chains, repairs to concrete soffits fixed beneath the wharf’s service duct and replacement of suckback fuel pumps.

JLL engaged structural engineering firm WGA and Duratec Limited as the Head Contractor for delivery of this project, which reached completion in February 2024.

The year-long construction stage of this project took place during live wharf operations. Coordinating construction works alongside the activities of a live site is a challenge enough, however the very nature of a wharf’s placement brings with it some additional unique obstacles. Tide timings had to be carefully considered as this affected when the supporting piles could be wrapped. To navigate this process underneath the wharf, diving works took place to erect scaffolding and a barge was also used to access the piles.

Staging the construction works was a vital process in managing these multiple challenges, especially with the location also being home to a penguin nesting site. The penguins in this area usually moult on Garden Island where Parkes Wharf is situated, rendering them land-bound as their feathers aren’t waterproof during this time. To help mitigate disturbance to the penguins, particular works were scheduled to align in the window after this moulting period and prior to their breeding season. Other measures included reducing machinery sound and vibrations during works by selecting plant with lower sound outputs where possible.

Protecting marine life was balanced with the threat of invasive marine pests in the area such as Didemnum Vexillum. This invasive species can smother native organisms and habitats, so efforts to prevent growth of this consisted of an intensive marine pest removal program involving water blasting.

The approach to complete this project was focused on creating a sustainable asset with reduced ongoing maintenance costs.

It was a great opportunity to utilise recycled materials where possible in the restoration works, with the new service walkway created using 1 tonne of 90% recycled plastic planks. Compared to timber planks, these are not prone to degradation and wear so will therefore be a more durable solution overall.

In addition, material waste created from the top deck, pile, sumps, headstock, rail and fuel pump repairs were all recycled, staying mindful of our penguin neighbours during the project and beyond.