Submarine installation was carried out by Prysmian’s cable-laying vessel Cable Enterprise. Roughly half of the length across the sea bed was jettable, here cable was buried using Prysmian’s Sea Mole jetting tool. For the remaining length, specialised trenching equipment was used. The project also required HVAC cables for a ten-kilometre route in the UK, linking two substations on the coast.
Crossing the channel, which has some of the world’s heaviest marine traffic, was a big challenge. Furthermore, this was a ‘fast track’ project, to be completed in a limited, tight time frame. However, several interesting challenges that weren’t part of the tender! The on-shore route demanded special attention to protection of wildlife including badgers, dormice and birds, for example. Furthermore, the converter station in the UK is near Solent Airport in Hampshire, which meant the cable had to cross the airfield. That meant factoring in height restrictions at the landfall interface with the runway, limiting use of cranes.
Owners of small aircraft were worried electromagnetic interference from cables might affect compass systems. Prysmian had already done a study into this during the tender phase, but the mathematical results were not clear for the aircraft owners. So several meters of cables were buried, and the aircraft owners were asked to pass over them and check whether they saw any effect on their compasses – which remained unaffected. A UK yacht club that sailed near where the work was being carried out was also visited, to explain the planned activities and which areas were to be avoided at certain times. Communities living near the shore were also taken into account as special measures were taken to avoid noise
What’s more, in Northern France measurements along beach had to carried out quickly without leaving a trace before June, when large number of tourists visit for D-Day celebrations.