132kV Electrical Distribution Network Upgrade

Large-scale distribution network upgrades to improve capacity and reliability

Highest available scores achieved for final design review, leading to contract extensions

Innovative and industry leading solutions developed to repurpose existing infrastructure

Client: Sellafield Ltd

Increasing capacity

A large-scale and bespoke project, the upgrade of the Electrical Distribution Network will enhance the reliability and capacity of the network that powers Sellafield Ltd’s processing plants, facilities and offices. It will see the installation of two new 40MVA step-down grid transformers (GTX and GTY) on an existing decommissioned substation site. The new step-down transformers will provide feeds to a new 11kV substation as well as being connected to an existing, dual circuit transmission tower located in the centre of the substation.

BakerHicks were appointed to deliver multi-disciplinary design services on this project, originally for the outline design but extended to include the provision of engineering support during the project procurement phase and client’s engineer services during the construction phase. Key services included:

  • Design of new, fully operational 132/11kV Grid Connection substation and two new 132kV cable circuits
  • Condition assessment, structural analysis and redesign of an existing 132kV Overhead Line (OHL) circuit and removal of a redundant 132kV OHL
  • Primary layout design including plant specification
  • Producing procurement specifications, an overarching specification and division of responsibility documents
  • Evaluation of contractor’s tender offers, technical reviews and providing support during the construction phase

Client-focused approach

A sustainable and innovative design, our engineers made use of the existing infrastructure wherever possible. The existing OHL terminal towers from the decommissioned route were reused and new downleads installed to concrete blocks, making cost and time savings by removing the need to construct two new tension towers and four gantries. As part of this process, our engineers developed industry leading 3D wire clearance check diagrams and conducted an options appraisal exercise, ensuring the solutions were the best fit for the site and client’s needs as well as being buildable. Further cost savings were made by carrying out in-depth cut and fill analysis of the ground, enabling excavated soil to be reused and avoiding expensive landfill charges.

With multiple stakeholders involved in the project, maintaining close communication with all parties was extremely important. Our team held regular design presentations and workshops, keeping all stakeholders involved as the design developed. This helped considerably with the multitude of different reviews, including individual discipline, multidiscipline, assistance, constructability and HAZCON, required to take place, each involving different stakeholders. By keeping all those involved up to date and engaged throughout the process, our engineers were able to fully understand each party’s specific requirements and ensure the design reflected these.

The client-focused and adaptable approach of our design team meant that the initial design received the highest available scores for the final design review. This resulted in BakerHicks being asked to provide further engineering support during the procurement and construction phases.

Once completed, the network upgrades will provide reliability of electricity supply, especially during increased load periods or changing demands, ensuring the Sellafield processing plants, facilities and offices within the site are kept operating.