Gwynt y Mor bombs: World War II explosives to be detonated 

Three World War II bombs found on the sea bed at a windfarm will be disposed of through a series of controlled explosions.

A plan has been drawn up for a series of detonations that will take care to mitigate any damage on fish, seals and the historic 19th Century Resurgam submarine wreck which lies nearby.

RWE Innogy UK is building 160-turbines about eight miles off Pensarn, Abergele, and its related company Gwynt y Môr Offshore Windfarm Ltd applied for the licence after the unexploded bombs were found. An exclusion zone has been set up since the discovery by a Remotely Operated Vehicle (ROV), which was surveying the seabed as part of an operation to lay cables at the wind farm on January 28.

The license has only been granted after a careful examination by Natural Resources Wales of the local environment with a view to public health, the health of other users in the sea and wildlife. A timescale has not been released, but a Natural Resources Wales spokesman said: (on Friday)“We have issued a marine licence application to Gwynt y Môr Offshore Windfarm Ltd to undertake controlled explosions of the unexploded bombs.

“We consulted with a number of technical advisors such as Cadw and Centre for Fisheries and Aquaculture Science to ensure that the risks to fish and protected wrecks in the area, such as the Resurgam submarine were effectively mitigated.

“A marine mammal mitigation plan has been developed to address potential impacts on the area’s mammals.”

Chris Holden, a diver from Chester Sub Aqua Club, knows the North Wales coastal waters well. On any detonation at sea, Mr Holden, of Higher Kinnerton in Flintshire, said: “They are going to have to be careful. The sea eight miles out will be between 15 and 35 metres deep. A gas pipe runs through the windfarm, there’s the protected wreck of the Resurgam two miles south east of the windfarm, and the wreck of the Ocean Monarch which teems with life such as fish, conger eels and lobsters.”

The 27-tonne Resurgam II, designed by a Manchester clergyman in 1879, was thought to be the world’s first powered working submarine. But it sank off Rhyl en route from Wallasey to the Royal Naval base in Portsmouth in 1880.

But Mr Holden, who has found practice bombs and equipment in Tremadog Bay, added: “You expect something ‘bomb-shaped’ with a tail fin but the tail fin tends to disintegrate.”

A photograph of a British “practice bomb”, taken by Paul Kay, of the Marine Conservation Society, and found off Aberdaron some years ago sheds some light on what the devices off Pensarn could look like.

Mr Kay, of Llanfairfechan, said: “Natural Resources Wales had legal requirements by the European Union and UK Government to follow over porpoises dolphins and turtles.”

He added spotted rays, skates and fish such as plaice, dab, flounder, sole and red gurnard are also found in Liverpool Bay. In 2012, one Ordnance disposal specialist called Kölbel demanded more guidelines about detonating old bombs. A spokesman had said: “To blow up a sea mine in situ is very difficult for us as we have to check before what animals are in the area and how we can protect these areas against the detonation .”

RWE has imposed an exclusion zone around the site but construction work is continuing as normal.

Once the bombs are gone, and the windfarm is fully operational later this year, RWE Innology expect it to employ more than 110 people long term, from the new multi-million pound operations and maintenance base, at the Port of Mostyn.