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Jan De Nul successfully executes cable repair work for TenneT in the German Bight


  • Jan De Nul executed this cable repair as part of the framework agreement for repairs between TenneT and Jan De Nul Group.
  • Less than 50 days were needed to perform the engineering, vessel mobilisation, removal of the damaged and installation of the new cable.
  • Cable-Laying Vessel Isaac Newton and Multi-Purpose Vessel Adhémar de Saint-Venant executed the repair job simultaneously.

Jan De Nul Group has successfully repaired TenneT’s AC108 cable connecting the Trianel Borkum offshore substation with Tennet’s DolWin alpha convertor station. The repair job is part of the Service Level Agreement for cable repairs that Jan De Nul Group and TenneT entered into in 2019.

TenneT engaged Jan De Nul Group for the repair of a cable fault located within the 500-meter zone around the DolWin alpha platform, 75 kilometers off the German coast north of the island Borkum. This offshore platform connects three wind farms in the German North Sea to the German extra-high voltage grid, and is therefore vital for these wind farms to get the green energy ashore

Within less than 50 days, Jan De Nul performed the specific detailed engineering, the vessel mobilisation, the replacement of the damaged cable section, as well as the burial of the new cable and joint.

Benjamin Foubert, Manager Offshore Cables at Jan De Nul Group: We are very proud of this very well organized and swift repair. The extensive pre-engineering efforts we performed in view of this repair framework agreement clearly paid off. Achieving the full repair in such a short notice resulted in a minimal disruption of the offshore grid connection. Thanks to the close and pro-active cooperation between all parties involved we were able to complete this campaign successfully, which included our two vessels working simultaneously in close proximity of the offshore platform.”

Working simultaneously and close to the platform

For this repair job, Jan De Nul mobilised its Cable-Laying Vessel Isaac Newton and Multi-Purpose Vessel Adhémar de Saint-Venant. First, the Adhémar de Saint-Venant deburied the damaged cable section, including its cable protection system which was buried under large armour rock.

The Isaac Newton loaded the spare cable and repair joint in Emden, recovered the damaged cable section offshore and subsequently installed the new cable and joint with success. Jan De Nul’s jet-trenching vehicle PT1, installed on-board the Isaac Newton, completed the repair campaign by burying the new cable section 1.5 meters below the seabed.

Read more on the Service Level Agreement: https://www.jandenul.com/news/offshore-cable-repairs-ensure-uninterrupted-supply-electricity

About Jan De Nul Group
Design. Build. Connect. Jan De Nul Group shapes water and land. Worldwide. From complex services to the offshore energy and energy transition sector, over large dredging and defence works on the edge of water and land, to challenging civil and environmental works. Well integrated competences and investments lead to creative, sustainable and innovative solutions. In this way Jan De Nul Group delivers results that produce satisfied customers. Today, but also tomorrow. –
www.jandenul.com