Scottish subsea technology specialist Ecosse Subsea Systems (ESS) has completed a second major seabed clearance project for gas and oil producer and energy supplier DONG Energy on what will be one of the world’s largest offshore wind farms.

ESS cleared more than 3 000 boulders at the site of DONG Energy’s Race Bank offshore wind farm, located off the Norfolk and Lincolnshire coast of the UK.

Race Bank will consist of 91 turbines of 6 MW each. The £5-million contract followed the successful completion of a similar project by ESS on DONG Energy’s Westermost Rough offshore wind farm off the Yorkshire coast of the UK.
ESS teams mobilised several vessels in two campaigns, including the Siem Topaz and Siem Sapphire vessels, on a multiphased workscope which lasted about 175 shipping days.
The company deployed the latest version of its SCAR 2 Seabed System – a multipurpose plough capable of boulder clearing, trenching and various seabed route preparation works. Additionally, a multifunction remotely operated vehicle grab was used to remove boulders and debris, which were more sparsely located or situated in awkward positions.
The boulder clearing took place across the export corridor, array cable routes and turbine locations, with 30-m-plus clearance corridors created using multipass capability.
ESS commercial director Keith McDermott said: “With the SCAR Seabed System we have set the standard for technology which is reliable and robust in the delivery of fast and efficient seabed clearance projects. We were working in some very difficult environmental conditions and with a variety of soil conditions and the SCAR proved its worth on both counts.”
He noted that, while the company is constantly reviewing SCAR to introduce improvements that provide savings to the client, this latest version SCAR 2 has a 15-m-wide capacity, compared with earlier 10 m models.

“We have built up a wealth of experience in the renewables sector and the SCAR Seabed System is a pioneer in seabed and cable route preparation work scopes,” McDermott said, adding that ESS is targeting several planned European wind farm projects where the company believes it can add value to the construction phase.