National Grid has announced that its work to lay underground cables through the Mendip Hills in Somerset as part of the connection of the Hinkley Point C nuclear plant to the transmission network is now 60 per cent complete.
The 400,000-volt cables are being installed along an 8.5-kilometre route from Loxton in the south to Sandford in the north to avoid the use of overhead power lines in the Mendip Hills Area of Outstanding Natural Beauty.
The cables are being placed in four trenches, approximately 2 metres wide, 1.8 metres deep and a few metres apart. Soil is carefully removed and stored, and the bottom of each trench lined with sand.
The cables are being laid in lengths of between 650 metres and 1 kilometre and connected in jointing bays, where a temporary tent is installed to make sure they are safely connected in a clean dry environment. They are then covered with cement-bound sand and a protective tile cover.
After the trenches are filled with the soil stored from the excavation, the land will be reinstated by December 2023. The entire project is due to be completed by 2025.
In an update on the project, National Grid said the cable pull is now more than 60 per cent complete, having pulled almost 64 kilometres of cables since it started in February, with most expected to be in place by the beginning of 2022.
The company said the removal of Western Power Distribution’s existing overhead lines between Bridgwater and Sandford is also due to be completed by 2022 and will leave part of the Mendip Hills pylon-free for the first time since the 1960s.
Robbie Griggs, project engineer for National Grid, said: “We’re delighted with progress and are really making the most of the better weather during the summer months when the ground conditions are most favourable. It’s great to be playing our part in meeting low carbon energy targets as well as transforming the Mendip Hills for all to enjoy.”
In addition to underground cables, the Hinkley connection project involves the installation of 49 kilometres of overhead power lines – mostly using the new “T-pylon” design rather than traditional lattice towers.
Last year, Ofgem revealed it had reduced the allowed budget for the connection project by £60 million. National Grid Electricity Transmission requested a budget of £716 million but was only allowed £656 million.