Posted on October 19, 2026
By Tom Pashby
US engineering and technology services contractor Amentum has been awarded a £22.3M, ten-year contract by Sizewell C’s main contractor the Civil Works Alliance (CWA) to design marine and tunnelling works for the nuclear power plant in Suffolk.
The CWA is formed of Balfour Beatty, Bouygues Travaux Publics, Laing O’Rourke and Sizewell C.
The contract covers a three-year design project followed by seven years of design support. The scope of works includes the design of three 3.5km offshore tunnels, marine shafts, tunnel-to-shaft connections, marine heads, onshore galleries, connections to the main civil works and a fish return system.
The fish return system is designed to return fish to the sea which are incidentally taken into the cooling system, which will circulate “enough water to fill 4,200 Olympic swimming pools every day”, Amentum said.
Amentum senior vice president Loren Jones said: “We will bring proven nuclear design experience, replicating and enhancing lessons learned from Hinkley Point C, where we led equivalent scope.
Amentum added it would subcontract major tunnelling design support to Jacobs and 3D reinforced concrete detailing to Adda.
Jones continued: “Working together again enables us to maintain continuity, leverage experience from Hinkley Point C to optimise the design, and reduce delivery risk on one of the UK’s most significant infrastructure projects.”
