CASE STUDY: Balfour Beatty

The onshore sprayed concrete lining (SCL) tunnels at Hinkley Point C

Balfour Beatty is contracted to deliver three major packages of works for EDF at Hinkley Point C.  We were first appointed to deliver the electrical works 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. The Reference Design for a total of 14 tunnels and shafts at Hinkley Point C included 300–600 mm thick sprayed concrete lining (SCL).  A sprayed concrete lining involves applying concrete onto the exposed surface to provide a strong and permanent lining.  The Reference Design would have meant c.8550m3 of concrete equating to 3506tCO2 (assuming 0.410 tCO2 /m3 ).

However, collaborative working between engineering and design teams over the application of innovative techniques the team resulted in achieve a significant reduction in the levels of embedded carbon. The SCL Manager and team worked closely with the designer to approve a Lean Design involving a much thinner layer of shotcrete supported by rock bolts. This meant c. 6410 m3 of shotcrete and c. 88 tonnes of steel.  This equates to 2784 tCO2 (assuming 0.410 tCO2 /m3 for concrete and 1.77tCO2/t for closed loop production steel) a 21% reduction in CO2