The offshore wind farm Borkum Riffgrund 1 is located around 37km north of the isle of Borkum.
Lys Rhilinger, Offshore Installation Manager of the foundations, at DONG Energy, said: ”I’m very happy that we have successfully completed the installation work. The cooperation within the team was very good and has become more and more routine in the course of time. Together with the nice weather which we’ve had during the last weeks, we now had a turnaround* of the Pacific Orca loaded with four foundations in less than four days. This is almost half of what we had hoped for during the planning.”
(*A turnaround is the cycle from loading in Eemshaven, sailing to the construction site, installation of the four foundation and going back to Eemshaven.)
Storage of the more than 600 tones heavy steel foundations for the offshore wind farm.
All in all 77 of these monopile constructions were anchored to the seabed. At the same time, the connecting pieces, the so-called transition pieces, were also installed. The 78th foundation will be a suction bucket jacket. It is a prototype with a three-legged steel construction with bucket foundations which will use a vacuum-assisted installation method and will be installed for the first time in an offshore wind farm.
Preparing for the installation: A noise mitigation tool is being used. This silencer guarantees that all noise levels stipulated by the authorities are met. Søren Sørensen, the Foundation Project Manager responsible for the installation of monopiles and transition pieces, said: "We’ve made the right decision to use this optimised installation method in relation to mitigation of underwater noise during piling. It has never been used in this way before and we’ve received excellent results.”
As soon as the foundation was installed into the seabed, a crane lifted the approximately 330 tonnes heavy and approximately 25 meter high transition pieces on top of the monopile foundation. It contains a landing stage, ladders and internal and external working areas. Later on, the transition piece will support the tower of the wind turbine.
When fully operational in 2015, Borkum Riffgrund 1 will be able to supply green power corresponding to the annual consumption of approximately 320,000 German households.
