Kier and BAM Land £600m Contract to Upgrade Devonport's 10 Dock

Kier and BAM have secured a £600m main works contract to upgrade Devonport's 10 Dock for submarine maintenance. Plymouth dockyard operator Babcock awarded the deal, moving the KierBAM joint venture from early contractor involvement into the main works phase.

The overhaul will prepare 10 Dock for deep maintenance of the Royal Navy's Astute-class attack submarines. It's one of the most significant defence infrastructure commitments in the UK's current construction pipeline, and it lands with a joint venture that has been embedded at the site for years.

What will the upgrade involve?

The engineering scope is concrete-heavy and precise. Existing dock walls will be strengthened, which narrows the dock itself, while part of the floor will be replaced with a reinforced concrete base supporting a new submarine docking cradle.

The wider redevelopment extends well beyond the dock basin:

• A heavy-lift gantry crane
• Five telescopic cranes
• New workshops and support buildings

Together, the works transform 10 Dock into a facility capable of handling the deep maintenance cycles that the Astute-class fleet demands.

Who is delivering the programme?

KierBAM first secured the main civils framework back in 2022, giving the joint venture a three-year footing at Devonport before this main works award. Costain and Mott MacDonald are also supporting Babcock on the wider programme.

The joint venture has been scaling up its presence on site. This summer, it launched a recruitment drive to bring in 120 people for the next phase of work at Devonport — a signal of how labour-intensive the main works will be.

Craig Small, managing director for energy & environment at Kier Infrastructure, framed the project in national terms. "This is a critical piece of infrastructure to support the UK's defence resilience, and builds on our experience across the UK's nuclear and defence sectors," he said.

Ian Hubbard, managing director of social infrastructure, nuclear and defence at BAM UK and Ireland, pointed to the long game. "Our ongoing work at Devonport serves the evolving requirements of the UK Royal Navy, helping to maintain and improve the availability of its current and future fleet," he said.

What does this change for Devonport?

For the Plymouth dockyard, the award confirms a sustained pipeline of heavy civil engineering work stretching years ahead, anchored by the Royal Navy's submarine programme. For the wider defence construction sector, it shows Babcock consolidating its delivery model around a joint venture that already holds the framework — continuity over competition.

And with 120 recruits joining the next phase, the project's footprint will be felt as much in Plymouth's employment figures as in the dock's reshaped concrete walls. The upgraded 10 Dock, once finished, will underpin maintenance capacity for the Astute-class fleet for the long term.