The survey area comprised three separate locations. Firstly, the Welsh inshore section of the project, secondly the Irish inshore section and thirdly the route development work.
The main objectives of the survey were as follows:
- To acquire side scan sonar and multibeam echo sounder data at the Irish end of the proposed cable route.
- To acquire side scan sonar and multibeam echo sounder data at the Welsh end of the proposed cable route.
- Confirm given locations of existing cable crossings utilising magnetometer data and detailed sea-bed condition within the crossing area utilising side scan sonar and multibeam echo sounder data.
Bibby HydroMap's own dedicated survey vessel Freja was utilised throughout the survey period on a 12 hour basis for the duration of the survey works.
Data acquisition involved multi-beam bathymetry, side scan sonar system and magnetometer data. For the majority of the acquisition, systems were run simultaneously, with the exception of a small amount of infill acquisition. Three parallel survey lines were run at each location, with a spacing of 40m along the length of the section, giving a corridor width of approximately 100m. Cross lines were generally acquired at 1km intervals. Multi-beam and magnetometer infill data was acquired at a line spacing of 20m where necessary.