Wind energy – Saint Brieuc
The jack up vessel AEOLUS operated by the company Van Oord, in charge of drilling and installing the foundation piles for the offshore wind farm, left the Bay of Saint-Brieuc today for its home port in the Netherlands (Vlissingen), a decision that was approved by the authorities.
At the same time, Ailes Marines confirms the continuation of the pre-trenching activities currently underway on the site, carried out by the company Prysmian with the vessel AETHRA.
Ailes Marines provides details of the incident: on Monday 14 June 2021, at 6:30 am, an incident was reported by the Captain of the vessel AEOLUS to CROSS Corsen (Centre Régional Opérationnel de Surveillance et de Sauvetage) and to the maritime coordination of Ailes Marines (MCC).
This incident occurred during the second round of drilling since work began on 3 May 2021. The electronic safety system of the drilling jig detected a sudden leak of about 100 litres of hydraulic fluid.
Immediately, the teams on board made dealing with the problem their priority. All ongoing drilling and installation activities were halted. An ROV, a remotely operated underwater vehicle, was deployed to confirm the leak and locate the source.
Once the location of the leak had been identified, the inspection confirmed that it was not possible to repair it without reassembling the drill jig on board the AEOLUS. It was therefore immediately decided to initiate its recovery, while drilling operations on the three piles were already well advanced.
This extremely sensitive template recovery phase, which took 24 hours, was carried out under the supervision of the two support vessels, TSM Kermor and REM trader. Their role was to identify any potential contamination during this recovery phase and thus avoid a more serious incident.
The investigation into the incident by the judicial police and the maritime gendarmerie is still ongoing. At this stage, Ailes Marines confirms that the source of the leakage is not due to structural damage to the template, but to a hydraulic connection that became loose during the work.
The incident resulted in the release of PANOLIN HLP SYNTH hydraulic fluid into the marine environment. 48 hours after the incident, the contractor Van Oord estimates the volume lost at 170 litres.
The hydraulic fluids used by Van Oord
Van Oord uses hydraulic equipment for its drilling operations. These tools work with a hydraulic fluid that has been specially developed and designed for work at sea. PANOLIN is classified as a ‘readily biodegradable fluid’ according to the international OECD 301B criteria, with a low environmental impact. On 15 June 2021, after several overflights carried out by customs, the Préfecture Maritime confirmed in its press release: “the evolution of the favourable situation […] since the surface iridescence, clearly visible yesterday over several kilometres, has now completely disappeared”.
Close cooperation with the authorities
Hearings and samples were taken by officers of the judicial police and the maritime gendarmerie on 15 June 2021, on board the vessel AEOLUS. These samples were given to the Centre of Documentation, Research and Experimentation on Accidental Water Pollution (CEDRE) and will enable the pollution to be characterised more precisely. The representative of Ailes Marines met with the Minister of Ecological Transition, Barbara Pompili, on 15 June 2021 to explain the incident and the means implemented by Ailes Marines to resolve it. Ailes Marines reiterates its commitment to work with the authorities and all stakeholders during the construction phase of the wind farm and its operation.
Return of the AEOLUS to its home port and continuation of pre-slicing activities
The vessel AEOLUS left the bay of Saint-Brieuc today for its home port in the Netherlands (Vlissingen). As a result, Ailes Marines and Van Oord have decided to temporarily stop the drilling work to focus on analysis and improvement of the tools, in order to ensure an optimal resumption of the drilling work. As a reminder, in December 2020, Ailes Marines decided to use the sole technique of drilling to install the foundation piles, in order to reduce impacts, particularly noise emissions. This demanding choice required investments and innovative developments in the field of engineering and underwater equipment. At the same time, the pre-trenching operations of the inter-turbine cables are continuing with the multifunctional vessel AETHRA. In December 2020, Ailes Marines decided to fully enshroud all the inter-wind turbine cables. The complete sinking of the cables represents a major step forward for the safety of navigation and for the maintenance of fishing activities within the Saint-Brieuc wind farm.