Cable Trenching

The Project

JBS were contracted by NSW and Fletcher Marine to provide Sea Axe Controlled Flow Excavation services at the Nordegrunde OWF in the German North Sea. The work scope was to assist client to identify and log the position of the cables transiting 70 metres out and up to the individual monopiles. Proof of cable lay and acceptable required protection depths for the cables was completed for a total of 19 monopiles and 38 cables.

The Challenge

Sea Axe was selected due to its ability to work in shallow tidal waters with strong currents in an environmentally challenging area. Depth from natural seabed was 5 metres transiting gradually to 1 metre depth, 2 cables per location with every transition route pre-surveyed.

The Solution

Data was recorded by Fugro and JBS Gemini Multi Beam Sonar equipment to produce a post operation proof survey report for the client. Seabed comprised mixed medium strength clay up to 3 metres below natural seabed with firm clay from 3 to 5 metres depth. JBS Sea Axe standard equipment was used with no requirement for the ancillary jetting system. Project was a success with the cables trenched to client specification at an average rate of 1m/min to 4m/min.