General – cable system
Aberdeen-based Rotech Subsea has completed a significant export cable de-burial and re-burial scope of work off France’s Atlantic coast for a global submarine cable system giant.
Having mobilised in Q2, 2021, CFE and suspended jet trenching specialist, Rotech Subsea successfully completed the de-burial and re-burial of two export cables, deploying its next generation RS2 controlled flow excavator (CFE) on the 480MW Saint-Nazaire offshore wind farm off France’s Guérande peninsula.
The project comprised de-burying cables C1 and C2 situated at 2m below MSBL, with the cables re-buried to the same depth following jointing operations by the client. Rotech Subsea’s RS2 controlled flow excavator was selected due to its high flow capabilities which deliver excellent de-burial performances. The ability to use varying nozzle sizes on the tool results in extremely efficient burial operations, whilst maintaining a narrow trench.
The subsea spread of equipment was mobilised for Saint-Nazaire on the Zwerver 1 in Q2, 2021. It was deployed via crane to operate in water depths of between 8-30m LAT, experiencing soil conditions including dense sands with a hard layer present at 2m.
The RS2 operated extremely effectively de-burying the cable to client spec with 1 pass at progress rates of between 2-3m/min. Burial depth was achieved in 1 pass at a rate of 1-2m/min with the client requesting a second flushing pass as a contingency.