Potential UXO identification at RTE’s Saint-Nazaire Offshore Wind Farm

James Fisher Renouvelables (formerly Mojo Maritime) was awarded a contract with Réseau de Transport d’Electricité (RTE) to identify potential unexploded ordnance (UXO) along the proposed route for the export cable at the Saint-Nazaire Offshore Wind Farm.

Located between 12km and 20km off the coast in the Loire-Atlantique region of France, the Saint-Nazaire Offshore Wind Farm comprises 80 turbines, capable of producing 480 MW of electricity.

The challenge

James Fisher Renouvelables was tasked with identifying potential UXO in water depths ranging from 0.3m to 25m, ahead of clearance work by the French Navy along the proposed route of the wind farm’s export cable.

The solution

The three core elements of James Fisher Renouvelables’ subsea services capabilities – diving, survey and remotely operated underwater vehicle (ROV) utilisation - were employed during the two-month project in June and July 2020.

Two vessels and 35 specialist personnel were mobilised to complete the work, including the DP2 vessel Pacific Worker, which was utilised on the offshore element of the project along with a Schilling HD WROV. For nearshore work, the TSM Dora was used by a team of experienced divers to carry out identification work.

Favourable tides meant the Pacific Worker was able to work as far inshore as possible, completing operations up to a depth of 9.5m.

The results and benefits

81 potential UXO targets were identified during the project, with two confirmed as UXO for removal by the French Navy.

James Fisher Renouvelables worked with RTE’s nominated UXO consultant and the local French authorities throughout to ensure all restrictions were adhered to, in light of the project taking place during the COVID-19 pandemic.