• Renewable energy

Clearing the seas of unexploded wartime debris

James Fisher's bomb disposal expertise is once more in demand at wind farms off the coast of Germany.

James Fisher Subsea has been at work off the coast of Germany helping to clear unexploded ordnance (UXOs) from the site of the proposed Nordergrunde wind farm.

The contract, with German wind farm developer, wpd, required the JF Subsea team to locate, excavate, and identify targets so any unexploded devices could be safely detonated by German authorities.

Although the team is hugely experienced in this field, the job posed technical complications because the shallow water around the Nordergrunde site is tidal and can be rough meaning the teams had to work in zero visibility. Two vessels were deployed, both with ROV teams onboard. Specialist divers were used by day and ROVs worked at night to speed the clearance process.

Bob Macmillan, technical diving director at JF Subsea says,

'Although much of the ordnance we retrieved turned out to be normal debris (such as anchors, chains and wires), the area is littered with UXOs (shells and grenades from both world wars) and our search identified 37 positive targets - some with multiple devices.'

UXOs deemed safe to move were cleaned and identified then returned to the seabed for 'wet storage'. They could then be picked up later and transported to a designated sandbank which dries out at low water so they could be disposed of by officials. Provision for any deemed unsafe was to attach them to a large airbag and tow them (by aluminium vessel 'Fast Fisher') to a safe spot for controlled detonation.

Bob adds,

'Many wind farms in this area face these UXO problems, and the additional experience we are getting with this contract puts us in a great position to tender for more contracts of a similar nature in the future.'