Van Oord’s jack-up Aeolus has left the bay of Saint-Brieuc and is en-route to her home port in Vlissingen, the Netherlands after the installation of foundations at the Saint-Brieuc offshore wind farm was halted due to a leak of hydraulic fluid in the drilling equipment.
Van Oord is in charge of transporting and installing 62 jacket foundations for the wind turbines, three pin piles each, and the four foundation pin piles for the offshore substation. A total of 190 pin piles will be installed at the 496 MW wind farm.
The installation work at the site some 16.3 kilometres off the coast of Brittany started in early May.
However, during the second round of borehole drilling, the installation work had to be stopped after it had been discovered that the drilling equipment used was leaking hydraulic fluid.
The sudden leak was detected by the electronic safety system of the jig serving as a guide for the drilling, Ailes Marines, the developer of the Saint-Brieuc wind farm, said.
The crews on board made dealing with the problem their priority immediatelly, halting all the ongoing drilling and installation activities, Ailes Marines said.
An ROV was deployed to confirm the leak and locate the source.
Once the location of the leak was identified, the inspection confirmed that repairs were not possible without reassembling the drilling jig on board the Aeolus.
It was therefore decided to stand down the vessel and recover the equipment. The drilling operations on three pin piles were in advanced stages at the time of the incident.
The template recovery phase, which required 24 hours, was carried out under the supervision of two support vessels, TSM Kermor and REM Trader. Their role was to identify any potential contamination during the lifting phase, Ailes Marines said.
Ailes Marines said that the leak of the hydraulic fluid was not caused by any damage to the structure of the jig, but by a hydraulic connection that loosened during the work.
48 hours after the incident, Van Oord estimated that 170 litres of PANOLIN HLP SYNTH hydraulic fluid leaked.
PANOLIN is classified as a “readily biodegradable fluid” according to the 301B international standards, with low environmental impact, Ailes Marines said.
The maritime prefecture confirmed in their press release ”…the evolution of the favorable situation […] since the iridescence of surface, clearly visible yesterday for several kilometers, has now completely disappeared.”
The investigation of the incident by the judicial police and the maritime gendarmerie is still in progress.
Local authorities have taken samples and will characterise the level of pollution more precisely in the coming days.
Ailes Marines, a wholly-owned subsidiary of Spain’s Iberdrola, plans to commission the Saint-Brieuc wind farm in 2023.