Using a precision technique, the “Nordnes” will place small rocks in a ‘donut’ shape around the site of 77 of the 90 foundation locations of the wind turbines to reduce the likelihood of scour and protect the cables when they are installed.
Scour protection is needed for wind turbines foundations, as well as other types of marine structures, due to changes in water flow patterns that may cause a lowering of the seabed immediately surrounding them.
Dutch company Van Oord has been contracted to carry out the wind power work, which will be done in two phases. In the second phase, larger rocks will be placed in the same pattern after all the foundations and cables have been installed.
Project Director Rune Rønvik said that the arrival of “Nordnes” on the site of the wind farm means construction work has officially started on site.
“This work will prepare the site for the arrival of the first foundation for installation at the end of next month. Each foundation is made to individual specifications and will be between 50 and 55 metres long, with a 4.2-5.2m diameter and weighing from 400 to 600 tonnes,” he added.
The “Nordnes” will be on site at Sheringham Shoal, between 17 and 22km off the coast of North Norfolk, until March 18 when it will return to Norway to collect its second load of rocks. It will arrive back in the Greater Wash on March 22, working until March 30 when it will dock for its annual service. The final rock placement work will be completed around early June.
The Sheringham Shoal Offshore Wind Farm is owned equally by Statoil and Statkraft through the joint venture company Scira Offshore Energy Limited. Statoil is the operator for the wind energy project during the development phase. Scira will be the operator of the wind farm.