National Grid submits Snowdonia tunnel proposal
8 April 2020Great Britain – National Grid has proposed to move 3.5km of overhead power lines underground. If approved, a 4.4m-diameter, 3km-long tunnel will be dug in the area of the Dwyryd Estuary in Snowdonia, allowing for the removal of 10 pylons and significantly improving the aesthetic of the landscape.
The project forms part of a GBP 500M (USD 620M) programme to mitigate the visual impact of existing electricity infrastructure in nationally protected landscapes. National Grid has called the project the Visual Impact Provision (VIP).
The tunnel will probably be excavated by slurry machine and segmentally lined over a period of 280 days.
The tunnel crown will be at variable depths, but no less than -15m OD and of the 135,000m3 of excavated material, some 13,000m3 will be soft alluvium with the remainder being rock.
The project also calls for shafts and permanent access provision at each end of the tunnel. If approved, works would begin in 2021 with the pylons finally taken down in 2026.
Further information on the proposal, which has been undergoing various consultations for the better part of a decade, can be found here: http://snowdonia.nationalgrid.co.uk/planning-application/
