Blyth Offshore Demonstrator

We designed and construct the world’s first major float-in gravity base foundations (GBFs) for the Blyth Offshore Demonstrator Project located in the North Sea, 5km off the coast of Blyth, Northumberland.

The turbines are the world’s largest foundations, pushing the boundaries of civil engineering in offshore structures, using several innovative methods, including the float and submerge technique.

The five reinforced concrete gravity bases are unique in that they were constructed in a dry dock and floated to their final position. The bases were lowered onto the sea bed and filled with ballast before the wind turbines were added. This minimised the construction period in the open water and low installation noise reduced the pollution risk and disturbance to marine mammals. This is an environmentally sustainable solution and by reversing the process during the de-commissioning stage, the structure can be brought back to land where the materials can be reused and recycled after a 25 year life span.

The wind turbine blades each have a sweep of 165m, 30m more than the London Eye. The windfarm benefits the local community and the turbines are able to generate enough electricity to power approximately 34,000 homes in the UK.

The key features of the project:

• Number of GBFs: 5
• Turbines: Vestas V164, 8.3MW
• Water depth: 40m
• Overall height: 60m
• Base diameter: 30m
• On bottom weight: 15,000t

Building Information Modelling (BIM), an intelligent 3D model-based process was used extensively on the project with digitalised point cloud surveys used to position the roof panels.

Last year BAM were awarded the Institute of Civil Engineers (ICE) North East Robert Stephenson Award 2018 for ‘Large Project of the Year’ and the Civil Engineering Contractors Association (CECA) North East ‘Project of the Year’.