EGS International Ltd (EGSi) were contracted by Centrica Renewable Energy Limited (CREL) to undertake a hydrographic, geophysical and UXO survey within the area of the Docking Shoal Meteorological Mast. A jack-up vessel will be used to remove the decommissioned Met Mast on Docking Shoal, with the platform and above section of the mast being removed and the remaining subsea section of the monopole being cut off to 1 metre below seabed level. Prior to the jack-up vessel’s arrival, a UXO site clearance survey was required to enable the vessel to safely jack up close to the Met Mast. An Acoustic Wave and Current Profiler (AWAC) seabed frame was also known to be located within the vicinity of the Met Mast. However, its position was not known and survey data was required to accurately locate this frame. The water depths across the site around the met mast range from 6.5 metres below LAT (eastern extent) to 12.5 metres below LAT (south and western extent). The mean sea level depth at the proposed survey area is 13.5 metres. The survey specifications were to: • Acquire bathymetric data with 100% coverage within the pre-defined survey area • Acquire high density magnetic data to allow UXO identification and analysis • Acquire high resolution side-scan sonar data with at least 100% coverage within the pre-defined survey area to identify targets on the seabed and, thereby, assist with UXO identification • Acquire high resolution shallow seismic data to identify buried objects • Acquire side-scan sonar, magnetic, seismic and bathymetric datasets to identify obstructions which could impede the arrival of the Jack up vessel, specifically, potential items of UXO, significant objects and man-made features on the seafloor • Acquire MBES data to determine the depth of the seabed relative to the met mast so that the mast can be removed from the correct level (at least 1m below the seabed).
Multibeam Echo Sounder and Bathymetry Data
Sub-bottom Profiler Data
Side-scan sonar Data and Derived Data