EGS Provides Subsea Cable Route Survey in Solent
- Operations & Maintenance
A-2-Sea Solutions Ltd, a company specialising in the installation and maintenance of subsea fibre optic telecommunication cable systems and on behalf of BT Plc, are developing two new submarine telecommunications cable routes connecting Lumps Fort, Southsea to Puckpool, Isle of Wight.
EGS were contracted to undertake marine geophysical and topographic surveys to provide detailed seabed information for use in cable system design, installation, survivability and subsequent maintenance plans, the company informed.
The investigation area posed 2 primary challenges to survey activities; namely the high traffic area of Portsmouth Harbour and the Port of Southampton, and long stretches of shallow water at either landfall. EGS worked to reduce the impact of these factors on operations through detailed preparations for project execution and line planning bearing in mind the highly variable tide to best use high and low waters, improving survey efficiency. This plan meant the topographic survey was undertaken on a low water spring tide whilst the geophysical survey was carried out during the high water spring tide to achieve optimum overlap between the topographic and geophysical surveys.
The survey was then split into three phases, the first being the topographic survey of the landfalls, secondly a multibeam and side-scan sonar survey of the marine section to identify hazards for route development was conducted. This was then used to design the third phase, a seismic and magnetometer survey for UXO identification.
To allow sufficient time for route development between the second and third phase of operations, data processing, reporting and charting was performed on a daily basis to reduce the turnaround time between completion of each phase of survey and submission of data, EGS said.