Duratec recently completed repair works to Parkes Wharf and looks forward to continuing its presence at WA’s Garden Island.

Return to roots

In 2015, Duratec was awarded its first contract with the Department of Defence – concrete and steel repair works to the low-level bridge that connects HMAS Stirling, located on Garden Island, to mainland WA. Since then, the company has delivered Defence projects across the country – for both the Estate Works Program (EWP) and the Capital Facilities and Infrastructure (CFI) branch.

Recently, Duratec returned to where it all began and successfully completed remediation works to HMAS Stirling’s Parkes Wharf. Over the years, the company’s dedicated Defence division has become well acquainted with HMAS Stirling and has extensive knowledge not only of the base’s assets but also of Defence protocols and processes. Upon being appointed head contractor by project delivery services provider, JLL, Duratec was able to mobilise on site and begin works seamlessly and efficiently.

About the base

HMAS Stirling on Garden Island is part of Fleet Base West and is the largest naval base in Australia. Its primary purpose is to provide operational and logistics support to the Royal Australian Navy ships, submarines and aircraft based there. These vessels include Collins Class submarines, support vessels and numerous ANZAC Class frigates.

Parkes Wharf – ready for an upgrade

Parkes Wharf, which was built in 1976 and berths both ships and submarines, had experienced corrosion and concrete cracking across the deck and service tunnels. As is to be expected from a 50-year-old maritime structure, some features of the wharf had become redundant and needed to be removed. One example was a railing, embedded across the deck, which had once serviced ship-loading and crane operations.

What does a wharf restoration involve?

The project was broken down into the three key focus areas:

Wharf remediation

  • Remediation of concrete cracks, patch repair and spalling to top of wharf deck
  • Remediation of concrete cracks to soffit and walls within service duct
  • Remediation and replacement of steel members and grating in service walkways
  • Concrete repair of service duct sumps
  • Concrete repair of headstocks
  • Cleaning of corroding material from concrete soffit of service ducts
  • Replacement of bolts to 19 fenders
  • Replacement of chains on dolphin fenders
  • Installation of cathodic protection system to slow rate of corrosion and reduce ongoing maintenance

Structural pile maintenance

  • Concrete patch repair of pile encasements
  • Wrapping of steel piles below concrete encasement
  • Encasement of piles where concrete encasement could not be repaired

Fuel pump replacement

  • Replacement of quarantine and oil fuel installation suck-back pumps in service tunnels

Challenges faced and overcome

The construction stage of the wharf restoration took place over a year and the project team faced various challenges along the way. Duratec drew upon its experience and expertise in the remediation of marine infrastructure to tailor solutions that would overcome any hurdles. The main considerations were as follows:

Working around live operations

It was vital for Duratec to minimise disruption to live wharf operations. This required the implementation of a variety of measures, including:

  • Strong stakeholder engagement
  • Careful planning and programming of works
  • Use of construction techniques that allowed flexibility to move workfronts
  • Protecting marine life

Little penguins – the smallest species of penguin – use Garden Island as a breeding site during winter. Duratec staged the works to mitigate disturbance to the penguins, while works required close to nesting sites took place outside of breeding season. To further minimise disruption, the crew used equipment with lower sound outputs, thereby reducing noise and vibrations.

As well as protecting marine life, Duratec needed to manage the threat of marine pests, such as Didemnum vexillum. This invasive species can smother native organisms and habitats so efforts to prevent its growth consisted of an intensive marine pest removal program involving water-blasting.

Navigating tides

Works carried out underneath the wharf needed to be carefully timed in order to navigate tides. This meant there was a window of just a few hours each day when piles could be wrapped. As well as meticulous scheduling, Duratec employed divers to erect scaffolding and a barge was used to access some of the piles.

The next chapter

Following the successful delivery of the Parkes Wharf restoration project, Duratec, in a joint venture with Ertech (DEJV), has been awarded two more Defence contracts at HMAS Stirling. Both are for the early contractor involvement (ECI) phase of projects that are part of the base’s preparation for the Submarine Rotational Force – West (SRF-West).

SRF-West refers to the rotational presence of AUKUS partners at HMAS Stirling, beginning 2027. The base will host one UK and up to four US conventionally armed, nuclear-powered submarines on a rotational basis.

The first contract is for the planning phase of maritime infrastructure upgrades to accommodate visiting submarines. The works will involve piling and dredging. It is the fourth such project secured by the DEJV at HMAS Stirling over the last five years and a continuation of works for local teams that
have been on site since 2017.

The second contract is for the planning phase of a new, fit-for purpose controlled industrial facility to support the maintenance of submarines.

These contracts demonstrate Duratec’s marine infrastructure capabilities and recognise its ability to deliver large-scale Defence projects. Duratec looks forward to collaborating with all stakeholders on these and other upcoming projects at HMAS Stirling.

And so, Duratec’s journey with Defence at Garden Island continues.