Abstract
On the instructions of Offshore Design Engineering Ltd (ODE), acting on behalf of E.ON UK Solway Offshore Ltd and E.ON UK Offshore Energy Resources Ltd, Osiris Projects were commissioned to undertake a mid-construction geophysical survey covering the proposed Robin Rigg Offshore Wind Farm development site. The survey was undertaken using Osiris Projects own dedicated survey vessel, MV ‘Freja’ during the period 28th June to 6th July 2009.
High-resolution side scan sonar, swath multi-beam and single beam bathymetry and magnetometer data were acquired along all survey lines, in order to accurately map the
seabed within the wind farm development area. Main survey lines were run at 100m centres, with cross lines at 200m centres. Additional lines were run 25m either side of
individual turbine rows in both NNE-SSW and WNW-ESE orientations, giving four complete passes at each turbine location.
The primary objectives of the survey were to map bathymetry and seabed features, including the presence of any magnetic anomalies within the wind farm area and to
assess the condition of any recently installed inter-array cables.
The survey included detailed bathymetric data collection around each of the recently installed turbine bases, to monitor the extents of seabed scouring. More detailed
bathymetric data collection was also carried out around the location of the west and east sub-stations and their immediate surroundings, where inter-array cables will be more
densely concentrated. It was also necessary to carry out a number of infill multi-beam bathymetry lines, to ensure total coverage within this area, due to the shallow water
depths encountered. In addition, the export cable route was surveyed for the first 3km from the offshore substation, using a full survey spread. The cable route was surveyed at a 75m line spacing.