Subsea power cable scheme linked to Noss Head is making 'excellent progress'
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"Excellent progress" is being made on the Shetland subsea power project linked to the massive switching station currently under construction to the north of Wick – and scrap metal has been removed from the seabed along the way.
The £660 million high voltage direct current (HVDC) scheme by energy firm SSEN Transmission will involve the installation of a 260km subsea cable from Shetland to Noss Head.
The first phase of boulder relocating work along the proposed cable route has been completed by NKT, the lead contractor for all cabling works. This involved clearing a 100m-wide corridor to move any obstacles.
Subsea equipment deployed from a specialist vessel, Seawell, was brought in to help manoeuvre boulders away.
Prior to the boulder clearance work, a survey was carried out to identify whether any unexploded ordnance was on the cable route. This was described as "standard practice".
No UXO was identified, meaning work could continue as planned. However, the survey did locate some scrap metal and other debris along the route, and this was recovered by the vessel.
Back on land, the project team completed horizontal directional drilling to the south of Noss Head lighthouse where the subsea cables will make landfall. This drilling method is used to install ducts beneath the ground through which cables can be pulled, with the aim of causing minimum disturbance to the surrounding area.
The horizontal directional drilling took around three months to complete. It required diving operations and marine surveys in support of the land-based effort.
Teams are now preparing for the first subsea installations this summer. This will involve the specialist vessel NKT Victoria installing the first cable length.
SSEN Transmission lead project manager Chris Finnigan said: “We’ve made some really excellent progress in recent months with regard to the Shetland HVDC link which allows us to move forward on connecting Shetland to the mainland and opening up a clean energy corridor for transporting electricity to and from the islands.
“Completing the horizontal directional drilling work was a crucial milestone, and the team has worked tirelessly to overcome major challenges including working through the complex geological make-up of the ground conditions at the Noss Head cliffs, as well as safely mobilising and demobilising the drilling spread and the vessels required for the supporting marine operations.
"It’s a huge achievement and one that those involved with the works should be proud of.
“The first stage of subsea boulder clearance marks another integral step ahead of the HVDC cable being installed, and the team from NKT and its subcontractor Helix, including all those on board the Seawell vessel, did a fantastic job in creating a safe subsea corridor for the future cable.
“As is standard practice we carried out specific surveys in order to check for UXOs along the cable route, and we’re pleased that no UXO targets were identified within the cable installation route. The survey did, however, identify some scrap metal debris on the seabed, and although this would not have impacted our project we worked with NKT to remove these items and have them disposed of properly onshore.
"As a responsible developer we aim, where possible, to leave a positive impact on the environment in which we operate and small actions like this are something we aim to achieve whenever we can.
“In general the project continues to make great strides forward and we are now gearing up ahead of our first subsea installation campaign which is scheduled to begin this summer.
“We thank the local community and stakeholders for their cooperation and understanding while we continue with this crucial project, and as ever we’ll work to keep informed as we move through the pre-construction phases of the Shetland HDVC link project.”
The project is on track to be completed by 2024.
