Export cable surveys underway for Norfolk Vanguard & Boreas OWFs

The Haven Seariser 2 jack-up vessel has been deployed off the Norfolk coast in the UK to collect seabed data for Vattenfall’s Norfolk Vanguard and Norfolk Boreas offshore wind projects.

The work, along with other surveys currently being carried out, will shape the design of what will become one of the world’s largest wind farms.

Haven Seariser 2 is on the nearshore off Happisburgh, where its geotechnical engineering team is taking borehole samples down to a maximum of 30 metres, which will ultimately help decide the installation methodology for the main transmission cables at their landfall in Happisburgh.

The vessel, owned by Red7 Marine, is expected to be in place for about another two weeks, depending on weather, work progress, and operations.

“The information gathered during these site investigation surveys will be used to fine tune the design of the export cable and associated installation techniques”, said Andy Galbraith, Vattenfall’s Head of Geoscience. “Horizontal directional drilling will be considered for installing the cable underneath the beach and the area of the shore which is submerged at high tide and exposed at low tide. These surveys will help determine the best technique to use”.

Similar sampling work is ongoing further offshore, with several larger vessels deployed as part of Fugro’s four-month campaign that started in July.

Offshore data will feed into planning the most efficient turbine locations within the array, appropriate foundation design, as well as the final cable route from the turbines to connect into the National Grid at the onshore project substation. 

According to Vattenfall, onshore site investigations have also begun around where the onshore substation will be built near Necton.

Norfolk Vanguard and Norfolk Boreas will together have an installed capacity of 3.6 GW and will produce enough electricity to power 3.9 million homes in the UK.

The UK Department for Business, Energy, and Industrial Strategy (BEIS) awarded development consent (DCO) for Vattenfall’s application to build the 1.8 GW Norfolk Vanguard offshore wind farm at the beginning of July. The DCO examination period for the 1.8 GW Norfolk Boreas has been pushed to 12 October.

Onshore construction of Vattenfall’s Norfolk projects is due to start in 2022/2023, while offshore works are scheduled to commence in mid- to late 2020s.