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Rotech Subsea completes French Atlantic Coast duct de-burial and post-lay subsea cable burial

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21 February 2022

Rotech Subsea has completed an important HDD exit de-burial and post-lay burial of a key subsea cable off the French Atlantic Coast. Contracted by a leading submarine cable player, the sector-leader in Controlled Flow Excavation (CFE) and suspended jet trenching mobilised its specialised trenching and sand wave clearance TRS2 tool in late Q3 2021.

Deployed from a support vessel A-frame, the cutting edge TRS2 tool operated in water depths ranging from 5-12m with currents ranging from 1.0-2.0kts and maximum sea state of 0.5m Hs. Soil conditions were very fine sand.

The TRS2 successfully de-buried the HDD from 4m below seabed, excavating a 10x25m box section in a grid pattern. The two centre lines were exposed and kept open in three further passes.

For the cable burial the TRS2 was again deployed by A-frame off the stern of the vessel with two deck winches used to position the tool. The cable was successfully lowered to 2m TOP. 

Rotech Subsea Director of Subsea, Stephen Cochrane, commented: "The TRS2 jet trencher was selected for this project due to its unrivalled jet power and flow capabilities. In fact, it’s the only non-contact system available in the marketplace capable of carrying out the scope of work.

"With both phases of this vital duct de-burial project completed ahead of schedule with client specification for de-burial and burial achieved with ease, this marked another very successful deployment for the TRS2.”

With enhanced capabilities, Rotech Subsea’s CFE suite of tools is firmly established as the method of choice for cable trenching in Europe and beyond. The Aberdeen-based contractor’s in-house research, development and engineering team has created a suite of 15 non-contact CFE, Suspended Jet Trenching tools. Further game changing enhancements were unveiled in January 2022 with the introduction of the new RS1-3 jet trencher. This latest next generation tool has been purpose-built for cable trenching, boasting higher soil cutting capabilities than existing tools.