Rotech completes cable work at first French offshore wind farm

Rotech Subsea has completed export cable de-burial and re-burial work at the Saint-Nazaire project, which is to become the first commercial offshore wind farm in France.

Rotech Subsea carried out the de-burial and re-burial of two export cables using its RS2 controlled flow excavator (CFE) at the 480 MW wind farm off the Guérande peninsula.

The project comprised de-burying cables C1 and C2 situated at two meters below MSBL, with the cables re-buried to the same depth following jointing operations.

The subsea spread of equipment was mobilized on the Zwerver 1 in Q2 2021 and was deployed via crane to operate in water depths of between 8 and 30 meters LAT, experiencing soil conditions with dense sands with a hard layer present at two meters.

“With another successful high profile contract completed on time and on budget Rotech Subsea’s CFE suite of tools is firmly established as the method of choice for cable trenching in Europe and beyond,” said the director of Subsea at Rotech, Stephen Cochrane.

“The enhanced capabilities of our Suspended Jet Trencher RS tools mean they can provide deeper and narrower trenches than ever before, with trenching speeds more than double that of competing older Mass Flow Excavation or other methods tools such as contact trenching systems and ploughs.”

The Saint-Nazaire offshore wind farm, also known as Parc du Banc de Guérande, will comprise 80 GE Haliade 150-6MW turbines.

Italian cable manufacturer Prysmian started the installation of the export cables at the project in August using its cable-laying vessel Cable Enterprise.

The company is also in charge of the delivery and installation of the wind farm’s inter-array cables in consortium with Louis Dreyfus TravOcean.

Once fully commissioned in 2022, Saint-Nazaire will become France’s first operating commercial offshore wind farm.