Rotech Subsea has completed cable de-burial and post-lay trenching works for the 630MW London Array offshore wind farm in the Outer Thames Estuary in south-east England.
The marine contractor said that its TRS1LD tool (pictured) was deployed from the vessel crane of the Forth Jouster and was used to complete the campaign in two passes, after which the cable was subsequently extracted.
This included the de-burial of 1000 metres of subsea cabling 1-1.5 metres below seabed.
The TRS1LD operated in depths of three to 10 metres and in soft sand soil conditions where currents ranged from 0-2.2 knots with general sea states between 1-1.5 metres Hs, Rotech said.
The subsequent post-lay trenching phase, carried out in October, saw the TRS1LD mobilised on the Nora B with the cable buried to a minimum of 1.5 metres below seabed, the company added.
A first pass excavated to 1.75-2.1 metre depth with a second survey pass confirming the cable had dropped to 1.5-2.6 metre depth below seabed.
Rotech Subsea director of subsea Stephen Cochrane said: “This London Array OWF assignment was another extremely successful deployment for our TRS1LD controlled flow excavator which is capable of delivering deep, narrow, precision trenches with speeds more than double that of competing mass flow excavation tools or other methods such as contact trenching systems and ploughs.
“All operations were carried out at speeds of 2-4m/min depending on the areas with each phase completed in two passes to the satisfaction of the client who we look forward to collaborating with again.”