This milestone marks the completion of Balfour Beatty’s sprayed concrete lining tunnel works.

Excavating through 600m of ground to create the tunnels, the team sprayed 9000m³ of concrete in order to stabilise the recently formed underground structures.

The job required over 1.6 million hours across the tunnels, with the programme of works completed to schedule.

The five onshore tunnels will now undergo secondary lining works, installing a number of reinforced rebar concrete structures to further stabilise the sprayed concrete.

In total, the team have successfully completed all five onshore tunnels for the critical cooling water system, responsible for transferring over 120,000 litres of water per second from the Bristol Channel.

Its four-year contract also includes the construction of three marine tunnels totalling over 9.5km in length and 7m in diameter.

Three portals have also been completed for launch of the tunnel boring machines needed to excavate the offshore tunnels for the main cooling water system.

The first TBM has already set off on its journey, having travelled over 2.5 kilometres, 33m under the Bristol Channel.

Alistair Geddes, Balfour Beatty Project Director for Hinkley Point C’s tunneling and marine project, said: “This is a significant step forward in the successful delivery of the first new nuclear power station in the UK for over 20 years.

“Achieving this incredible milestone is testament to Balfour Beatty’s unrivaled expertise in delivering projects of this scale and complexity.”