Jan De Nul’s intertidal trencher Sunfish has reburied a section of the export cable at Eneco’s Luchterduinen offshore wind farm in the Netherlands.
For this purpose, Jan De Nul modified its in-house designed and fabricated intertidal trencher Sunfish and reburied the nearshore section of the cable to a minimum depth of 2.5 meters below the seabed.
The export cable burial was over the last few years decreasing in depth due to morphological changes, therefore Eneco requested a reburial campaign to guarantee it will at all times remain sufficiently buried and thus protected.
Since the section of decreased burial depth was located in the nearshore zone, it was not accessible with typical offshore trenching vehicles and could not be easily accessed from the beach. Sunfish lowered the nearshore part of the cable working up to 1 kilometer offshore and a water depth of 8.5 meters.
Ernest Diepstraten, project manager at Eneco: “Eneco greatly appreciated working together with Jan De Nul constructively in delivering this project in time and in budget. We are pleased that, thanks to the work of Jan De Nul Group, the cable to our Eneco Luchterduinen wind farm is buried deep enough again so that the wind farm can continue to supply power to our customers.”
Specifically for this project, the Sunfish was modified to a suitable post-lay jet-trenching vehicle with two water pumps delivering each 1250 m³/hr jet water and 3.5-meter long jet swords.
To accurately locate the cable, the vehicle was further equipped with two sets of cable tracker sensors of SMD’s 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, Jan De Nul stated.
The Luchterduinen offshore wind farm comprises 43 Vestas V112 turbines located approximately 23 kilometers off the coast between Noordwijk and Zandvoort. The 129 MW project was commissioned back in 2015.