Consultancy Cathie Associates carried out a study that helped to reduce the noise in the water column created by monopile installation at Eon’s 385MW Arkona offshore wind farm in the German Baltic Sea.

Monopile installation was wrapped up in January, with Cathie's study having been completed during the planning stage.

A hammer energy profile was developed that allowed monopiles to be driven at reduced energy levels, while still achieving required target penetration depth, the consultancy said.

Noise in the water column produced by the pile driving process was reduced as a result of the new profile, compared with a standard hammer energy profile, it added.

Cathie Associates senior engineer Rui Silvano said: “We had to ensure the recommended energy profile was optimised to drive the monopiles to the required depth within the 180 minute time restriction required by the BSH in Germany, while verifying that the monopile fatigue during driving remained low despite the increased number of hammer blows associated with reduced energy.”

All 60 EEW-manufactured monopiles were installed by Van Oord’s Swanen, while Jumbo’s heavy lift crane vessel Fairplayer tackled Bladt-built transition pieces.

The Arkona project is located 35km off the island of Rugen and will feature 60 Siemens 6.4MW turbines.

The project is scheduled to reach full commercial operation in 2019.

Image: an Arkona monopile (EEW)