Offshore wind farm target investigation

Supporting Ørsted Energy's Race Bank offshore wind farm project

SafeLane Global was contracted by Ørsted Energy (previously DONG Energy) to conduct the investigation of ferromagnetic and acoustic contacts identified during previously conducted UXO surveys at the Race Bank export cable site, located off the North Norfolk coastline.

These potential UXO targets were located between four and nine kilometres offshore.

The total number of potential UXO targets for investigation was 58.  35 targets were buried and 23 were surface targets, (literally on top of the seabed).  

All targets were to be investigated in order to determine if they were UXO or not.

Marine target inspection operations

The overall objectives of the target inspection operations for SafeLane's marine department were:

• Inspection of potential unexploded ordnance (UXO) locations.  The locations were based on previously conducted UXO surveys over the site.  Also, a number of potential UXO locations were provided by Ørsted Energy for inspection and potential explosive ordnance disposal (EOD).
• Excavation of buried contacts to approximately 1 metre below the seabed for visual identification of UXO, or other debris.
• Removal of any debris that proved to be non-UXO related within the potential UXO locations.
• Auditable documentation of the inspection in the form of reports, high-resolution colour video, and still photos for installation purposes.

Using UXO clearance divers

Examining the requirements for the target investigation, SafeLane proposed of the use of a diving spread; utilising the skills of UXO trained clearance divers was accepted by the client and works commenced.

Bureaucracy and tides created a challenge

Due to tidal conditions and the extensive amount of ongoing works on the site, a significant number of challenges were encountered - not least the permit requirements for the site issued by the Marine Management Organisation.

This all meant that initially only the surface targets could be investigated while environmental considerations were taken into account before the below seabed investigations could commence.

SafeLane worked with the client to ensure efficient cost effective diving operations were conduced while the environmentally sensitive permitting issues were resolved.

Each target investigation location was conducted in a 20m x 20m box, several of which contained a number of discrete potential UXO targets. 

From the investigation works, two principle items of ordnance were identified and safely dealt with:

• one WWII 500lb general purpose British bomb and
• one 3” rocket with a 60lb practice rocket head.