Work begins on Sheringham Shoal Wind Farm site

The vessel will position rocks at selected foundation location in preparation for the start of the installation of the giant monopile structures next month.

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 project during the development phase. Scira will be the operator of the wind farm.

Situated 10 to 15 miles off the north coast of Norfolk UK, the $1.7bn joint venture project will feature 90 wind turbines, each measuring 80m high. When it comes on stream in 2011 it will generate 315MW of electricity, enough to power 220,000 homes.

Using a precision technique, the Nordnes will place 2 to 9 inch filter rocks in a donut shape around the site of 77 of the foundation locations to reduce the likelihood of scour and protect the cables when they are installed.

Scour protection is needed for wind turbine 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 dredging and marine construction operator Van Oord has been contracted to carry out the filter layer work, which will be the first stage of a two phase process. In the second phase, larger rocks will be placed in the same pattern to act as armour to the filter layer after all the foundations have been installed. The appointment of the contractor to undertake the armour layer works has yet to be decided.

Project irector Rune Rønvik said that the arrival of Nordnes on the site of the wind farm means construction work has officially started.

‘This work will prepare the site for the arrival of the first foundation for installation at the end of next month, he said. ‘Each foundation is made to individual specifications and will be between 50 and 55m long, with a 4.2m to 5.2m diameter and weighing from 400 to 600 tons.’

The Nordnes will be on site at Sheringham Shoal until 18 March, when it will return to Norway to collect its second load of rock. It will arrive back in the Greater Wash on 22 March, working until 30 March. The final rock placement for the filter layer work will be completed around early June of this year.