Vessel on Norfolk nearshore for seabed tests to shape wind farm final design

The 500-tonne Haven Seariser 2 is on the nearshore off Happisburgh while its geotechnical engineering team take samples for Swedish energy group Vattenfall’s Norfolk Vanguard and Norfolk Boreas developments.

The rig is a 29-metre long barge fitted with long support legs jacked down onto the seafloor. It is gathering borehole samples, down to a maximum of 30 metres.

The process will build an understanding of seabed sediment layering to decide the installation methodology for the wind farms’ main transmission cables at their landfall at Happisburgh.

Several larger vessels are working further offshore carrying out similar sampling in a four-month campaign by geo-data experts Fugro.

Onshore site investigations have also begun around where the onshore substation will be built near Necton.

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. 

Teams are collecting samples to learn about the properties of soil types at the site and are also completing cone penetration testing (CPT).  

These samples will be sent for testing in Fugro’s world-class soil testing laboratories in Wallingford, UK, and Nootdorp in the Netherlands. Data collected will be used to shape a ‘ground model’ for the wind farm and final cable design. Other laboratories carrying out specialised testing include GEO’s laboratory in Denmark.

The Haven Seariser 2 is expected to be in place for about another two weeks, depending on weather, work progress and operations.

Andy Galbraith, Vattenfall’s Head of Geoscience, said: “The information gathered during these site investigation surveys will be used to fine tune the design of the export cable and associated installation techniques.

“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.

“A jack up vessel provides a very stable sampling environment compared to other offshore drilling rigs and this is important to preserve the quality of the samples. It also helps that the current weather conditions are favourable for the campaign.”

The Haven Seariser 2, owned by Red7 Marine, of Ipswich, is the first locally visible sign of progress on the Norfolk Vanguard project, which is a key part of the UK’s energy transition and journey to NetZero.

The east coast is the focus of sustainable and decarbonised energy generation. Together, Norfolk Vanguard and its coordinated sister project, Norfolk Boreas, will produce 3.6GW of energy – enough to power 3.9 million homes or 10% of UK homes.

Beachgoers and residents have the opportunity of a rare close up view of the jack-up as it works, with day and night shift crews transported by boat the 25 miles from and to Lowestoft harbour.

The 1.8 GW Norfolk Vanguard was granted consent on July 1. Huge turbines for both Norfolk Vanguard and Norfolk Boreas will be so far from the Norfolk coast, where the winds are strong and constant, they will not be visible from shore.

The Southern North Sea’s shallow depth, coupled with its wind supply, makes conditions among the most favourable in the world for offshore wind projects.

Onshore construction of Vattenfall’s Norfolk Projects is due to start in 2122-23, with the prospect of many local jobs supported in local construction companies and relevant contractors.

Offshore works are due to start in the mid to late 2020s.  

The east of England’s long experience of offshore energy projects, supply chain companies based there expect to support construction and 25-year operation of the Norfolk projects.

Fugro is a long-term partner of Vattenfall and has worked on most of the world’s wind farms providing geo data to de-risk sites. It is one of the many specialist companies involved providing services to the burgeoning offshore wind sector.

Vattenfall ‘met’ with supply chain businesses hoping to work on the projects at this week’s virtual Southern North Seas 2020 conference., organised by the East of England Energy Group (EEEGR), which attracted more than 450 delegates.

The event, focused on the energy transition, brought together energy stakeholders to discuss how they can collaborate to deliver necessary actions to halt catastrophic climate change.