Blyth Gravity Based Foundations

Strukton Immersion Projects and Geocon succesfully performed the marine works as a sub-contractor for BAM for the Blyth Offshore Wind Demonstrator project. Geocon provided all survey and monitoring data durnig; float-up, river-transport, mooring, offshore-transport, installation and ballasting operations.

Blyth / Newcastle UK
Number of elements:
Gravity based foundation


The project was owned by EDF Energies Nouvelles Group and operated by EDF Energy Renewables. Strukton Immersion Projects, as subcontractor of BAM JV, was responsible for the marine scope, the float and submerge of five GBFs, including the sand ballasting and installation of the GBFs. Geocon provided all survey and monitoring data durnig operations. Each GBF weighs more than 22,000 tonnes when fully installed. They were immersed at a water depth of 40-45 meters. The float out and transport of the GBFs was started in July 2017. The five GBF elements were moored at a mooring location were the final works were performed before transport over the river Tyne. The GBFs were then brought to their final destination where the immersion with water was completed. After this process, the GBF’s were ballasted with sand to make sure they are stable to receive the top parts of the windmill. For this last step, SImP constructed a pontoon of 100 by 30 meters, containing a sand storage (8000 m3) and two pump systems consisting of pumps and a mixing unit to mix sand with water. The pontoon is custom-made and exclusively used for this project. The technique developed by SImP to use sand for the purpose of immerging the GBFs, is innovative and unique. In general, a wind mill has a life span of approximately 25 years. By using sand instead of concrete, the GBFs can be dismantled by removing the sand, after which the structures can be recycled.