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National Grid going underground in Eryri: tunnelling under the Dwyryd Estuary

Event organised by ICE

24 January 2024

This event has now ended

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As part of its national Visual Impact Provision programme, National Grid is seeking to remove some of the most visually impactful of its existing overhead lines in AONBs and National Parks.

In the Eryri National Park, the only solution to enable the removal of 10 pylons and 3.4km of overhead line that spans the estuary near Portmeirion, is to place the 400kV replacement cables in a tunnel deep under the estuary.

Driven by stakeholders and with the support of the community, the team is nonetheless operating in a highly built up and populated area, very popular with tourists. The geology and associated groundworks are extremely challenging and the team will need all its experience gained from the Feeder 9 gas pipeline under the Humber to deliver the project.

Senior project manager, Steve Ellison’s talk will explore a number of technical aspects of the work including the tunnel design and the Tunnel Boring Machine (TBM); safety and risk management; geology and groundworks; the stages of project delivery; crossing under roads and railways as well as the estuary; collaborative working with main contractor, Hochtief UK, and environmental mitigation.

It will also reference lessons learned and applied to the project and how the team has worked to support the community along the way.


Steve Ellison

Steve Ellison

National Grid

Senior Project Manager

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Steve Ellison

Steve Ellison is a senior project manager working for National Grid and is a champion for safe delivery of major infrastructure projects with over 30 years of major project delivery experience. He has recently completed the World recording breaking River Humber pipeline replacement project that involved the design and construction of a 5km estuary tunnel.

The challenges faced during the Humber project and lessons learnt have been key to the development of the Eryri VIP project.

For more information please contact:

Sara Horrell