Hinkley C Marine Works

Project Details

Project Description

LBA Role

Project Highlights


Hinkley Point C Nuclear Power Station, Somerset




2010 to 2017

Project Type

Cooling water tunnels for new nuclear power station


Construction Planning
Bid Management



Project Description

Hinkley C is a new nuclear power station being constructed adjacent to the existing Hinkley A & B power stations. The power station comprises 2 EPR reactors with a 3200MW capacity. It will be the first nuclear power station built in the UK for over 20 years. The marine works element of the project comprises the cooling water intake and outfall structures, both onshore and offshore.  

NNB Genco, working on behalf of EDF Energy, issued an ITT in September 2010 for the main elements of the power station, including the marine works. A joint venture of Costain and Sir Robert McAlpine prepared a bid for the work and, after two stages of a competitive tender, was successful and appointed Preferred Bidder. Subsequently, due to corporate governance, Sir Robert McAlpine withdrew from the joint venture and Costain continued to progress the works as a sole entity supported by LBA.

The scope of the marine works comprises:

  • 2 no. 6m ID intake tunnels, 3.5km in length
  • 1 no. 7m ID outfall tunnel, 1.8km in length
  • 1 no. 17.5m ID launch shaft, 40m depth
  • 700m SCL tunnels, varying sizes and profiles to connect cooling circuits to the power station
  • 6 no. offshore shafts to link diffuser heads with outfall and intake tunnels, 2 no. per tunnel
  • 6 no. concrete diffuser heads, constructed onshore and floated into position
  • Manufacturing plant for the precast concrete tunnel segmental lining
  • Fish return system installed using Horizontal Directional Drilling

Once confirmed as Preferred Bidder, Costain undertook a series of Early Contractor Involvement (ECI) phases to develop the construction proposals to a suitable level of detail to inform a detailed target cost and ultimate sign-off for the project by the EDF board, which was granted in July 2016. The UK Government subsequently gave their approval in September 2016.

LBA Role

LBA supported Costain with technical support to both the bidding and ECI phases. During the bid, LBA’s role comprised:

  • Management of the two-stage bidding process to ensure a successful commercial and technical submission
  • Construction planning for the tunnelling works, leading to compilation of a fully working construction programme for the scheme
  • Logistics planning for the scheme
  • Writing the technical submission for the bid submission
  • Contributing to the commercial submission by engaging and managing the specialist supply chain. 

During the ECI Phase and early construction phase, LBA’s role comprised:

  • Engineering management of the works, determining and directing the design of the tunnelling work
  • Interface management with the client, NNB Genco, in technical meetings concerning the tunnelling works
  • Construction and logistics planning for the works 
  • Writing the documents that eventually supported the approval of the scheme by the EDF Board.

The LBA team on site transferred to working for Balfour Beatty who are responsible for the construction phase of the works.

Project Highlights

LBA were responsible for the successful bid submission and provided last minute resources to get the bid submitted in the requisite timescales.

The entire planning of the tunnel works and interface with the other civil works contractors was undertaken by LBA. LBA also acted as Technical Experts for the procurement process for the Tunnel Boring Machines that were purchased for the project and establishment of the precast tunnel lining factory.

Accreditations and Affiliations