Repair of the main cable at Utgrunden Wind Turbine Farm

The client: Energi E2

The place: Öland, Sweden

Excavator	Cable-snit	Jack-up platform Explorer	Cable trench

The work: In June and July 2006 JD-Contractor A/S exchanged and embedded the main cable from the shore and approx. 2 kilometres out to the Utgrunden Wind Turbine Farm in Sweden.

Earlier in 2004 and 2005 JD-Contractor A/S had made a successful exchange of all the submarine cables between the 7 offshore wind turbines at Utgrunden Wind Turbine Farm.

The seabed close to the beach at Degerhamn exists of extremely hard materials, which meant that the cables had to be laid in excavated trenches, which involved the use of 2 excavating vessels.

The following vessels were used during the work:

M/S Honte:
1. Laying of the new submarine cable.
2. Moving the existing cable into the bottom of the trench.

M/V Lille Björn:
1. Assistance for M/S Honte and towing of the jack-up platform.
2. Transport of cable jointers, personnel and equipment.

Stf. Helle Saj:
1. Excavating of the trenches for the cables at a depth from 2.5 to 10 metres.
2. Covering of the cables at a depth from 0 to 2.5 metres into the seabed.

Jack-up platform Explorer:
1. The cable jointers used the Jack-up platform for cable splicing at sea.

Excavating vessel from Per Aarsleff:
1. Excavating of the trenches for the cables at a depth from 0 to 2.5 metres into the seabed.
2. Covering of the cables at a depth from 0 to 2.5 metres into the seabed.

Furthermore a diving team assisted during the entire work. At first they marked the existing cable with buoys from the shore and out. Then later they inspected and approved the excavating and covering of the trenches.

Approx. 800 metres of existing cable were recovered and replaced by a new cable.

Approx. 2,000 metres of trenches were excavated into the seabed where the existing and the new cable were moved into.