JD-Contractor involved with the world’s biggest submarine cable project...

In connection with the modernization of the high voltage grid through Jutland, 6 new 400kV and 3 new 150 kV cables were to be pulled across the Mariager Fiord.

As the landscape around the little town Mariager has a very high scenic beauty it was decided to pull the cables through pipes on the seabed of the fiord. JD Contractor ApS who has a great experience in the laying of pipes on the seabed was chosen to plan and lay out the 9 pipes needed as protection for the cables.

The pipes have a diameter of 355 mm and they were delivered in lengths of 21 meter to the working area at Kongsdal Harbour, where JD Contractor ApS had established a place to work. There the tubes were welded together, 3 at a time, to a length of 650 meters. Concrete ballast blocks were attached to the pipes and kept the pipes together to a section of three pipes.

The end of the pipe section was pulled out on the water controlled and held in position by the diving vessel M/S Honte.

When one pipe section was finished it was towed down to the site between Katbjerg and Bramslev. It was done very early in the morning before daylight. Only the early risers were able to see the spectacular view of the 650-meter long pipe section being towed through the harbour of Mariager.

As the pipe section reached the destination the ends were pulled into the docking channels already dug into the beach. Out at the fiord the tubes were positioned very accurately supported by our vessels T/B Lillebjørn and M/B Buizerd. When the pipe section was above its position water was pumped into the centre pipe and the pipe section was submerged down to the seabed. At the seabed the last positioning was made and water let into the last two pipes.

The time schedule for the project was strictly followed and with intervals of 10 days the next two sections were manufactured and placed at the seabed, next to the first pipe section and with an accuracy of a very few centimetres.