A SECOND World War mine threatening one of the UK’s most important gas pipelines is to be removed.
Oil giant Shell is calling in a subsea bomb squad to co-ordinate the operation in the North Sea, 62 miles off St Fergus, Aberdeenshire.
The 500-pound British-made mine lies beneath a pipeline responsible for 5 per cent of the UK’s daily gas supply.
The unexploded device has been monitored by the company since it was first discovered almost 20 years ago.
Last year, following a study of the mine, a “guard ship” was deployed to keep a watch on the area and warn away fishing boats.
A spokeswoman for Shell said: “Shell became aware of this unexploded ordnance in 1993.
“Since that time the company has regularly inspected the site and sought professional advice on how best to proceed.
“The consistent advice the company received was to leave the mine in position and continue to monitor it periodically.
“The development of new technology means that Shell believes it may now be possible to remove the mine.”
She continued: “Shell is considering technical options for the safe removal and disposal of the unexploded ordnance.” The company was initially unaware of the presence of the British-made mine – suspected to be an anti-submarine device.
The pipeline – known as FLAGS (Far North Liquids and Associated Gas System) – was completed in 1978 and commissioned in May 1982.
Liquids and gas from numerous platforms in the North Sea, including four Brent platforms, are transported through the pipeline every day to St Fergus.
Shell was initially advised to leave the device in place when the Royal Navy first inspected it in 1993. But the oil giant said it had always been keen to remove the mine and kept in close contact with Portsmouth-based unexploded-ordnance-disposal firm Ramora UK to find a solution.
Now, due to the new technology – known as a Remote Explosive Ordnance Disposal System, or REODS – Shell is looking to lift and dispose of the bomb safely in August.
It is understood that a bag will be attached to a lifting mechanism that is to be dropped to the sea bed.
The bag is designed to inflate around the mine and float to the surface. The bomb will then be towed to a safe area, lowered to the sea bed and detonated.
Ramora’s system has already played a key role in helping oil and gas operator Chevron North Sea deal with an unexploded mine found at a depth of 3,667ft, the deepest explosive ordinance disposal carried out to date.
The British Mk IV buoyant mine, the classic spherical design with protruding electrical switch horns, familiar from many films and documentaries, weighed 1,200 lbs in total with a NEQ (net explosive quantity) of 500lbs.
Before it could be made safe, the mine first had to be moved a distance of 1.5 miles and then detonated with a charge that was put in place using a remotely operated vehicle.
To carry out the procedure, Ramora UK made full use of its REODS system.
The delicate operation now faced at the FLAGS pipeline has seen executives from Shell meet with the Health and Safety Executive, Department of Energy and Climate Change, Grampian Police and the Royal Navy.
Numerous inspections were carried out.
Last September Shell commissioned a guard ship to keep watch over the unexploded mine because of the risk it posed.
A spokeswoman said that, while there was no platform or rig in the near vicinity, fishing vessels occasionally passed by the site making it necessary for additional safety measures.
The guard vessel has been ensuring that a safe distance is maintained between any passing vessel and the site.
Last August, a pipeline that delivers about 40 per cent of the oil produced in the UK into the country was shut down for five days so an unexploded mine could be removed.
The 105-mile pipeline system pipes some 500,000 barrels of oil ashore each day.
The BP Forties pipeline was closed off Peterhead for the German-built mine to be taken two-and-a-half miles away from the pipeline and detonated underwater.
It was found 25 miles off the coast of Peterhead last March.
A BP spokesman said at the time: “It didn’t pose any risks where it was, but we knew pretty quickly we didn’t want it there. It’s very rare that the whole system is shut down, but we are not taking any chances.”
BP shut down the pipeline while demand was lower.
The oil firm also made the most of the shut-down by carrying out maintenance on the pipeline.