Enhancing capability of Captain Cook Graving Dock: Thales team removes and replaces 20 tonne main flooding valve
The Captain Cook Graving Dock (CCGD) at Garden Island Sydney, is one of the largest ship repair and maintenance graving docks in the Southern Hemisphere, and is a critical strategic asset of the Australian Defence Force. The dock's two main flooding valves have been in continuous operation for over 75 years, necessitating a removal and replacement operation for them both, starting with 'Valve 10.' This project was years in the making and is a feat that represents the skills and capability of the Garden Island Team.
The CCGD is, to put it mildly, gargantuan. At 350m long, 45 metres wide, with a 230-million-litre reservoir that can be drained at the rate of an Olympic pool every 40 seconds, there needs to be incredible power behind the flooding and draining of the dock.
The two primary powerhouses that propel this activity are the main flooding valves. They average about 600,000 litres per minute, per valve, over the docking filling cycle, enabling it to be safely flooded in about 2 ½ hours.
As the CCGD has been in continuous operation for over 70 years, the primary valves, installed in 1943 by Scottish company, Glenfield & Kennedy Pty Ltd, were due to be replaced. The project itself kicked off in 2018 with a scoping and feasibility study to assess the intricacies and logistics of the project including safety considerations and delivery strategy.
In 2019, the detailed design phase for the associated valve pit infrastructure commenced, as well as casting of the new valve and, in 2020, although the project was steadily progressing, unavoidable delays caused by Covid associated restrictions impacted the project for the next two years.
Fast forward to July 2022, when the team received word that the valve was headed to Sydney. They kicked-off planning for the delivery phase works to determine critical activities including: HSE requirements, obtaining consensus on the sequence of tasks around docking movements and developing and testing of the Thales bespoke double isolation system.
While all elements of the project had their importance, the valve replacement works wouldn’t have gone ahead without the implementation of the double isolation system that stopped the pit from flooding while the team completed the replacement. Essentially, the double isolation consists of an inflated plug in the valve pit culvert with the stop log gate behind it to seal it off from the harbour. In the past, it was only the stop log gate that was installed to prevent any water ingress.
The physical removal and replacement of ‘Valve 10’ took place over two days and went seamlessly, with the 20-person team pulling together to execute the activity safely, efficiently and expertly.
Valve 10 is one of the largest critical infrastructure components in the Captain Cook Graving Dock. For some time, the valve has been inoperable, limiting the flooding efficiency to the dock during docking movements. With new valve 10 installed, the dock will be returned to near full operational capacity and capability in Thales’ ongoing support to the Commonwealth’s Defence readiness."
Phil Rogerson, Project Manager, Thales Australia Above Water Systems
The Dock at Garden Island is critical to providing the sustainment activities needed by the RAN to successfully achieve their mission. It’s important that it is operated and maintained to the highest standards possible, so that it continues to deliver the service required by the RAN. I am immensely proud of the team for having planned and executed this activity with excellence, including outstanding safety practices, and it’s a testament to their skill and the “capability” they represent at Garden Island to support the RAN."
Max Kufner, VP Above Water Systems