James Fisher Subsea has completed the location and excavation of unexploded ordnance (UXO) at the 111MW Nordergründe offshore wind farm located 16 kilometres off the North Sea coast of Germany.
Of the 224 targets identified, 72 were deemed to be UXO’s and had to be detonated with minimal impact to sea life, JF Subsea said.
“Due to the project’s potentially dangerous complexities- such as rough tide, heavily buried ordnance and inclement weather- the team was prepped to be ready at a moment’s notice whenever a suitable weather window opened up,” JF Subsea’s project manager, Max Clements , said.
“As with all UXO operations safety was of the upmost priority and from the planning stages we ensured we had project specific equipment, world-class expertise and encompassing method statements in place. These measures ensured the teams were safe, the UXO’s were removed efficiently and the client received a world class service.”
Due to the complex and unpredictable nature of the project, JF Subsea had to work within narrow weather windows and often in shallow waters with rough tides. Target location, ROVs, detonation specialists and bespoke UXO support vessels were all used as part of a turnkey solution, ensuring the precise and efficient delivery of the project.
Two vessels were deployed for the duration on the project, with specialist divers used to locate and remove the UXOs during the day and ROVs dispatched to detect and excavate through the night. This dual-pronged approach sped up the clearance process and reduced the delay to the client’s start date, JF Subsea said.
“Offshore wind turbine sites are often plagued with UXO’s and are a continual problem we come up against during construction. Due to the expertise JF Subsea showed throughout the excavation process we will most likely be using their services again,” Jan Patrick Daniel, offshore project manager at wpd Group, the developer of the wind farm, said.
Nordergründe is being constructed at a water depth of 10m, approximately 15km north-east of the island of Wangerooge.
The wind farm will feature 18 Senvion Type 6.2M126 turbines which are currently being installed and are scheduled for commissioning by the end of 2016.