The federal Department of Defence plans to spend $738.1 million on Garden Island works in preparation for AUKUS’ arrival at HMAS Stirling, in support of nuclear submarines slated to arrive in 2027.

The price tag attached to the maritime infrastructure and facility upgrades required to facilitate nuclear submarines under the trilateral defence pact between Australia, the United Kingdom and the United States was flagged in a submission to a federal public works committee today.

The submission outlines a total cost less GST and including contingency of $738.1 million, to deliver project management and design fees, construction, ICT infrastructure, furniture and fittings and equipment at Garden Island.

In its submission, the Department of Defence highlighted the suboptimal conditions of the current facilities at the HMAS Stirling base off the Rockingham coast.

The facility, described as having remained largely “unchanged since the mid 1990s”, was described as aged and disconnected, and in need of additional works to meet the “stringent requirements for the operation of nuclear-powered submarines”.

“This project is the first step in progressively developing HMAS Stirling over the next decade to becoming an operating base for at least half of the future nuclear-powered submarines by the early 2040s,” the submission said.

The plan includes upgrades to berthing infrastructure to support nuclear subs, and a new pontoon for small boats.

A radiological controls field office would be built, with plans for a controlled industry facility, a power station, a pure water processing plant and upgrades to engineering services infrastructure also on the agenda.

The submission also highlighted the importance of nuclear safety – with a safety case to be developed for HMAS Stirling separate of that being undertaken by the Australian Submarine Agency.

A new independent statutory regulator will oversee the nuclear safety and radiological protection – to be called the Australian Naval Nuclear Power Safety Regulator.

Defence said the facilities dealing with nuclear aspects of the project would be held to stringent requirements for regulatory approvals and licensing, with qualified nuclear safety designers and assurance professionals to be engaged to support design and construction.

The department said it had conducted two rounds of community consultation on its plans and would continue to engage key stakeholders.

Submissions to a parliamentary committee on the plans opened this afternoon and will close on July 4.

Work to support new Arafura class offshore patrol vessels and Hunter class frigates at HMAS Stirling is already underway.

Defence hopes for construction to begin in 2025, with a delivery date of 2027.

The federal government announced its intention to spend $8 billion expanding HMAS Stirling over the coming decade in March last year, as part of its AUKUS vision.