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£400,000 project underway in Mendip

A £400,000 project is underway in Mendip, Somerset to divert our network in preparation for a new nuclear power plant. 

Linesmen Rob Kirkby (left) and Ben Slater preparing the ‘H’ pole ready to accept the 33kV cable termination.

The undergrounding of over 3km of 33kV and 11kV overhead line – part of the preparation work for Hinckley Point C power plant – will have a number of benefits. It will improve the visual landscape for customers near the bulk supply point at Churchill, facilitate the network for upgrades needed for the plant and provide additional supply security during bad weather. 

The new 3.2GW nuclear plant is being constructed to supply low carbon energy to around six million homes when complete. Work on the infrastructure has already had a significant impact on our network.

Radstock Team Manager, Steve Blackwell explained the complexities of the Mendip project: “As well as the undergrounding of the cables, a 132kV tower will be repositioned to accommodate the additional load needed for the power plant. The diversions enable the 132kV F route to be taken down with no live exposed conductor beneath the tower line, while maintaining supplies and keeping network security to its maximum.”

Steve said the work was situated on a fast stretch of road between Congresbury and Churchill, accessed via a farm gateway, which often caused access challenges for HGV deliveries and plant machinery entering and leaving the site.  “The scale of the job, which covers 36 acres, was always going to be huge due to the size of the diversion. What made it more challenging were the ground conditions, with floods at this time of year, plus the timescale of having to complete the works within one month. This was due to network constraints, other planned works and environmental issues.”

With unstable ground conditions, it was essential that a temporary road was put in place to avoid any permanent damage to land. This meant safe access routes for staff and it also enabled effective access for vehicles likely to use the site. “Another unexpected challenge was the fact that we had all seasons at once with snow fall, torrential rain, then two weeks of sunshine,” said Steve. Work will continue on the tower and overhead lines until November. 

The Project in Numbers

  • 2km of 33kV 300mm2 copper ethylene propylene rubber (EPR) cable and 1.2km of 11kV 185mm2 aluminium EPR cable were used during this project
     
  • 20 HGVs were used for delivering materials
     
  • £80,000 of temporary road was installed to avoid any permanent damage to land. This meant safe access routes for pedestrians and it also enabled effective access for vehicles likely to use the site
     
  • It took one month to complete the undergrounding work due to network constraints, other planned works and environmental issues
     
  • Hinkley C is one of the biggest projects to affect WPD’s network and is currently the largest construction site in Europe
     
  • The power plant will supply low carbon energy to around six million homes when complete.

A view of a tower, showing the temporary road and the scale of the job.