DONG Energy says it has safely detonated or removed 41 items of unexploded ordnance (UXO) from World War II off the Norfolk, U.K., coast, after the explosives were discovered on the export cable route for the developer's 580 MW Race Bank offshore wind farm.
During a large-scale offshore inspection campaign on the Race Bank site, DONG found UXO items ranging from small rockets to larger 1,000 lb. high-explosive bombs. The most notable item discovered was a German Luftmine B ground mine containing a net explosive quantity of 698 kg of hexanite.
DONG says 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" were recovered to shore, where they were safely scrapped in approved facilities.
(A YouTube video of one of the planned explosions is available here.)
‘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," explains Eleftheria Melekou, site investigations project manager at DONG Energy. "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.’
A post-detonation search was also performed to observe any evidence of injury of marine life, including fish. DONG says the observation team reported very low fish kill from the disposal operations, while no cetaceans or other marine mammals were observed.
‘We have closely cooperated with the Marine Management Organisation and Natural England to ensure the least possible impact on the environment during this work," comments Klaus Skoust Mpller, program director for Race Bank at DONG Energy. ‘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.’
