Balfour Beatty breaks through on final Hinkley onshore tunnel

Balfour Beatty has completed the breakthrough of the longest and final onshore-cooling water tunnel at new nuclear power plant Hinkley Point C.

The milestone marks the completion of Balfour Beatty’s
sprayed concrete linking works at the plant – a method for large-diameter
tunnel construction using mechanical excavation and the application of sprayed
concrete to provide ground support.

Balfour excavated through 600m of ground to create the
tunnels, spraying 9,000m3 of concrete.

A total of 1.6m working hours were spent on the five onshore
tunnels, which will now undergo secondary lining works and the installation of
a number of reinforced rebar concrete structures.

When complete, the tunnels will transfer over 120,000 litres
of water per second to Hinkley Point C from the Bristol Channel. 

The same Balfour team has prepared three portals to
facilitate the launch of the Tunnel Boring Machines (TBM) which will excavate
the tunnels for the main cooling water system. The first TBM has already set
off on its journey, having travelled over 2.5 kilometres, 33 metres under the
Bristol Channel.

Alistair Geddes, Balfour Beatty project director for Hinkley
Point C’s tunnelling 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.”

Balfour Beatty is contracted to three major packages of works at Hinkley Point C. It was first appointed to deliver the electrical package in a joint venture in 2015, the tunnelling and marine package in 2017 and most recently the 400kV overhead line project on behalf of National Grid in 2019.