#ExplainingEnergy: Land drilling on a £1.1 billion transmission project

The installation of four cable ducts through the rock beneath Noss Head, north of Wick, and almost 500 metres out to sea has been successfully completed as part of Scottish Hydro Electric Transmission’s (SHE Transmission’s) £1.1 billion Caithness-Moray project.

While the ducts were being drilled around 20 metres beneath the base of the cliffs, a specialist member of the site team regularly monitored wildlife in the surrounding area to minimise any disturbance.  The coastal environment at Noss Head supports a diverse range of species and is a popular haul-out area for both grey and common seals.  Occasional pauses in work when seals were close to the site ensured that the mammals were able to rest undisturbed by the steady progress of the drill through the rock below.

The transition between land and sea represents one of the most challenging elements in the installation of the 100 mile High Voltage Direct Current (HVDC) link between Spittal in central Caithness and Blackhillock in Moray, which will enable the efficient transfer of up to 1,200MW of renewable power beneath the Moray Firth.  Following the completion of the drill, cables will be pulled through the ducts on to land next year when the marine installation work is due to take place.  Two of the four ducts installed will carry the main electricity cables, a third duct will contain the fibre optic cable used in the operation of the system, while a fourth is available as a spare.

SHE Transmission’s Lead Project Manager for onshore cable works Michael Blake said:
“The successful completion of the drill at Noss Head is a major achievement for our project – and particularly for the team that has been working hard on site over the past few months.  

“Working in any coastal environment presents a range of practical and environmental challenges. At Noss Head, our site team has taken great care to protect local wildlife from disturbance.  The resident seals have kept a curious eye on proceedings, but have not let our activity get in the way of their relaxation time.  By the end of 2018, electricity equivalent to the output of a large power station will be transferred 20 metres beneath them in a tiny fraction of a second, while they sleep on."

“The main onshore cable works are now nearing completion in Caithness and the ducts at Noss Head will enable the first stage of the cable’s journey beneath the Moray Firth. I would like to thank residents at Noss, Staxigoe, Papigoe and Wick for their patience and understanding while we have been working in the area.”