Press release
Ailes Marines opts for the drilling method to install the foundation piles, a technique with less impact on the environment.
Saint-Brieuc / Paris – December 18, 2020 – To reduce the environmental impact, Ailes Marines decided to use the drilling technique to install the foundation piles. This decision was made after years of engineering studies and following the completion of onshore and offshore drilling tests to maximize safety and environmental protection. This decision concerns all the locations of the 62 wind turbine foundations and that of the electrical substation.
● The initial solution combining drilling and driving abandoned
The Saint-Brieuc offshore wind farm site is one of the most complex in the world due to the nature of the very heterogeneous seabed, including extremely hard rocks such as sandstone, but also a sedimentary basin over part of The area.
Given these characteristics, Ailes Marines had from the outset of the project considered installing the foundation piles using both drilling and driving techniques.
But, aware of the impact of piling in terms of noise on the marine environment, Ailes Marines finally worked on developing innovative solutions with less impact.
● A drilling test campaign
Ailes Marines therefore had the Van Oord company carry out a testing campaign for a drilling tool during the month of September. Indeed, Van Oord is the company which will be responsible for transporting and installing the park's foundations and their piles. The test campaign aimed to:
❖ Gain experience, in order to improve installation methods, tools and coordination of different contractors.
❖ Gain better experience of sea conditions on site.
In this regard, Van Oord and Ailes Marines have already learned from the test results and implemented improvements for the installation campaign which will start in spring 2021:
❖ Confirmation of the use of a “jack-up” vessel to improve the stability of drilling operations.
❖ Optimization of drilling systems and on-board spare parts.
● Drilling, a technique with less impact on the environment
Thanks to the engineering studies and the various tests carried out on land and at sea, Ailes Marines selected the drilling solution for the installation of the piles of the 62 wind turbine foundations and that of the electrical substation, i.e. a total of 190 piles anchor.
The choice of drilling technique for installing the piles will significantly reduce the impacts of the work on fish species and marine mammals.
In measurements show that drilling work will generate noise of a sound intensity comparable, among other things, to cruise ships or container ships, or even to small boats such as speedboats or jet skis. These noise levels are no longer likely to cause a risk of mortality or severe injury to marine mammals. Note that a group of dolphins hunting was observed 1.5 km from the work vessel by the SOMME design office during slicing tests this summer (sound levels equivalent to drilling), thus demonstrating normal behavior at close range. activities.
Furthermore, for the drilling tests, the measured turbidities were lower than 5-6 NTU. The NTU (Nephelometric Turbidity Unit) is the standard unit for measuring transparency, directly linked to turbidity (suspended matter content). If the NTU is less than 5 the water is clear, between 5 and 30 slightly cloudy and above 50 the water is cloudy.
December
About Ailes Marines
Winner in April 2012 of a national call for projects with the Saint-Brieuc Bay offshore wind farm project, AILES MARINES is in charge of the development, construction, installation and operation of the park. offshore wind farm. It is a simplified joint stock company (SAS), 100% owned by IBERDROLA.
The key figures of the Saint-Brieuc Bay offshore wind project:
- 75 km2 of area
- 62 Siemens-Gamesa 8 MW wind turbines
- 496 MW of installed power
- 1,820 GWh/year of production, i.e. the annual electricity consumption of 835,000 inhabitants (heating included)
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