Over 40 items of unexploded ordnance (UXO) from World War II have been safely detonated or removed from the Norfolk coast, having been discovered on the export cable route for DONG Energy's Race Bank offshore wind farm.
During a large scale offshore inspection campaign on the Race Bank site, 41 UXO items were discovered, ranging from small rockets to larger 1,000lb high explosive bombs. The most notable item discovered was a German Luftmine B ground mine containing a net explosive quantity (NEQ) of 698kg of hexanite.
36 live, high explosive-filled items were destroyed in their current locations at sea using highly skilled specialist contractors, while five items certified as free from explosives (FFE) were recovered to shore, where they were safely scrapped in approved facilities.
Eleftheria Melekou, Site Investigations Project Manager at DONG Energy, said:
"As a routine part of the preparatory work before construction of an offshore wind farm, seabed surveys are carried out to ensure the seabed is clear of obstacles including unexploded ordnance. This is standard procedure, although the number of items discovered was a surprise and the most we have seen on a DONG Energy project to date.
"We used the help of specialist and highly-skilled companies to ensure all of the 41 items of unexploded ordnance discovered at Race Bank were safely detonated or removed without risk to the local community."
A marine mammal observation protocol was followed during the operation, with a dedicated marine mitigation vessel accompanying the vessel performing the works to monitor for the presence of marine mammals around the detonation positions. A post detonation search was also performed to observe any evidence of injury of marine life, including fish. The marine mammal observation team reported very low fish kill from the disposal operations, while no cetaceans or other marine mammals were observed.
Klaus Skoust Møller, Programme Director for Race Bank at DONG Energy, said:
"We have closely cooperated with the Marine Management Organisation and Natural England to ensure the least possible impact on the environment during this work.
"This has been a big and important task due to the number of UXOs involved, and we are very happy that the authorities have supported us in progressing the project."
To assist in managing the UXO risk, vessel operations were performed by experienced UK-based companies in the field – MMT, Ramora and Dynasafe Bactec, and were supported and supervised closely by a dedicated and highly skilled site investigations team at DONG Energy. Ordtek, a Suffolk-based company which provides third party UXO consultancy services, was able to certify that the risk at the site was reduced to levels as low as reasonably practicable.
Lee Gooderham, Project Manager at Ordtek, said:
"It has been a pleasure to work with DONG Energy on Race Bank. Not only is it a large and important renewable project, the environmental conditions and military history make it very complex from a UXO risk management perspective.
"The way in which DONG Energy has adapted to address those challenges is very impressive. The right level of effort has been implemented at the correct time, ensuring that UXO risks are reduced to as low as reasonably practicable, as required by UK legislation, and the project remains on schedule."
Race Bank, when operational, will have a capacity of up to 580 megawatts (MW), providing enough green energy to power over 400,000 UK homes