Jan De Nul successfully reburies export cable at Eneco’s wind farm

To this purpose, Jan De Nul modified its in-house designed and fabricated intertidal trencher Sunfish and successfully reburied the nearshore section of the cable to a minimum depth of 2.5 metres below the seabed.

Due to morphological changes the export cable burial was over the last few years decreasing in depth within the nearshore section. To guarantee the cable will at all times remain sufficiently buried and thus protected, a reburial campaign was requested by Eneco.

Since the section of decreased burial depth was located in the nearshore zone, it was not accessible with typical offshore trenching vehicles nor could it be easily accessed from the beach. Jan De Nul offered Eneco the solution by mobilizing its intertidal trencher Sunfish. The Sunfish successfully lowered the nearshore part of the cable working up to 1 kilometre offshore and a water depth of 8.5 metres.

Tom Baguet, Project Manager at Jan De Nul Group:

“Deepening the live export cable in a challenging intertidal zone with our unique in-house designed trenching vehicle Sunfish proves our expertise in various operational fields.”

Specifically for this project, the Sunfish was modified to a suitable post-lay jet-trenching vehicle with 2 water pumps delivering each 1250 m³/hr jet water and 3.5 m long jet swords.

The Sunfish was initially designed as a ploughing machine suitable for working in tidal areas. In this configuration, the Sunfish successfully buried export cables on the Race Bank project in the UK in 2016. Jan De Nul engineers converted the machine later into an excavator with a chain cutter, a configuration which was used for the burial of the Rentel export cable in Belgium in 2017. Today, the Sunfish successfully completed the Eneco Luchterduinen export cable reburial in jetting configuration by using water under high pressure.

To accurately locate the cable, the Sunfish was further equipped with 2 sets of innovative cable tracker sensors of SMD’s innovative tracking system ‘Artemis’ using the live tone of the cable. As a result, Eneco did not have to switch off the wind farm during the entire campaign.

Lee Carden, SMD Head of Sales for Artemis:

“SMD very much appreciated this opportunity to continue to trial our Artemis cable tracking technology on live projects. Following a robust series of offshore trials, this project enabled live cable reburial operations to be completed without turning off windfarm power.”