Monopiles, transition pieces for western France wind farm reach La Rochelle

Sarens is supporting DEME Offshore with construction of the Îles d'Yeu and Noirmoutier offshore wind farm in western France.

The development, offshore the Vendée coast in the Atlantic Ocean, is 11 km from the island of Yeu and 16 km from Noirmoutier. When complete, it will have a generating capacity of 496 MW.

At the port of La Rochelle, Sarens is responsible for the load-in, onshore storage and load-out of 61 monopiles, each 62 m long and weighing up to 1,200 t, and 61 transition pieces (35 m tall and weighing up to 440 t).

The company’s engineering team commissioned local groundworks specialist Charier to prepare seven pairs of dunes for storage of the monopiles. To handle these structures, Sarens has sent 45 axle lines of Kamag K24 Self-Propelled Modular Trailers (SPMTs) to the site.

Monopiles built in China are arriving at the quayside onboard the Boskalis Blue and Black Marvin transportation vessels, for storage onshore via load-ins over link spans with the SPMTs.

The transition pieces have been arriving in 16 shipments on the UHL Fresh vessel from Vlissingnen in the Netherlands. They are lifted onto the quayside and picked up for storage using 24-axle lines Cometto SPMTs with a transition piece handler.

More than 100 x 500-mm elephant feet (stools) have been created for storage of the transition pieces.

Sarens’ transition piece handler has to accommodate the structures’ higher than normal height to diameter ratio. The engineering team has to ensure at all times that the maximum speed, inclination and wind speed during these movements are substantially lower than usual.

The company has applied learnings from its previous work at La Rochelle port supporting the offshore Saint-Nazaire wind farm development in the same region.