Nordsee One

Challenge

Nordsee One offshore wind farm is situated approximately 40 km north of the island of Juist between the traffic separation area Terschelling-German Bight and German Bight Western Approach, with water depths ranging from 25 m to 29 m. 
The wind farm comprises 54 WTG foundations, each consisting of a monopile, transition piece and lower boat landing. The foundations will be equipped with a 6MW turbine and once fully commissioned, Nordsee One will be able to provide power for approximately 400,000 households. 

Our solution

 

The foundations were loaded onto the Heavy Lift Vessel ‘Innovation’ near the fabrication yard in the port of Cuxhaven. GeoSea carried out the offshore installation in compliance with strict BSH requirements, and with a high focus on noise mitigation while driving the piles. To dampen the noise level during installation of the monopiles a single big bubble curtain and tailor-made Noise Mitigation System were deployed. 
A special feature about this project was the bolted connection between the monopile and the transition piece. This involved a procedure involving direct hammering on the flange in order to obtain a case specific approval certificate (the ‘Zulassung im Einzelfall’ or ZiE).

Furthermore, during the transition piece installation, the bolt holes had to be perfectly aligned. Thanks to GeoSea’s highly skilled engineering department, this was realised by deploying a specially designed, automated remote alignment tool. Per foundation 124 M64 bolts had to be installed and torqued to the right value. 
In addition to the transport and installation of the monopiles and transition pieces, GeoSea was responsible for the scour protection. Consisting of a filter and amour layer, the scour protection was designed and installed by GeoSea’s sister company Tideway.

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