Due to its special location within the nature protection area, the project Butendiek has to take care of environmental issues, especially of noise mitigation during installation of the wind farm. In order to protect marine mammals during the installation of the foundations, the emitted noise has to be kept below a limit value which is targeted by the BSH.
During construction of Butendiek different methods will be used to protect the mammals and to minimize the noise caused by pile driving into the seabed:
1. By means of the use of seal scarer and pinger shortly before pile driving, and a soft start procedure at the beginning of pile driving (starting with low energy and slowly increasing) marine mammals will be gently constrained to leave the nearby range of construction area in an adequate time.
2. For the used monopile foundations in Butendiek the noise mitigation system will consist of a double-walled tube, which encloses the monopile completely and lower the emitted noise below critical values.
3. For the jacket foundation of the offshore substation a big bubble curtain surrounds the whole structure in a closed ring at the seabed. Here compressed air is pushed through little holes in the hose and rises as bubbles up to the sea level.
wpd will monitor the performance and success of the chosen methods through an intensive measurement program installed during construction and each pile driving event.