Both onshore and offshore surveys have been integral to the development of Sofia since early environmental impact assessment work to inform the original development consent application. As the projects moves through its construction phase, surveys will continue to remain an integral part of our activity.
In the lead up to construction and to finalise the wind farm design, a comprehensive six-month offshore site investigation was undertaken in 2020. Comprising geophysical and geotechnical surveys, the work included environmental grab samples, drop down video transects, sub-bottom seismic profiling, side-scan sonar, bathymetry and magnetometer surveys on the Dogger Bank array site along the 220 kilometre export cable. Likely the longest such cable route survey ever undertaken for an offshore wind farm, the information collected built up a comprehensive picture of the seafloor and sub seafloor conditions. The results informed the need for further surveys, the design of the final cable route, the exact landfall location and the most appropriate cable installation methodologies. Offshore surveys continue into 2021 with ornithological monitoring, seabed cone penetration tests and marine ecology research supporting our consents and engineering activity.
Onshore surveys have also been required pre-construction and will continue as the project's on-site works get underway including archaeology trial trenching along the cable corridor and at the converter station site, and site investigation surveys to check ground and other conditions.