Offshore Cable Installation - Lillgrund - Vattenfall

6.3 General comments on the inter-array cable installations
6.3.1 J-Tube Caps
In every foundation there was a j-tube from the seabed to the top of the foundation, which
was designed for the cable. One meter below the seabed, a bell-mouth with an enclosure
cap, was mounted on the j-tube. The enclosure cap had to be removed before the cable
pull-in, figure 23. Mud had filled in outside of the enclosure cap, requiring divers to vacuum
the space before every pull-in so the cap could be removed. Because of the water current
direction, clearing the space in front of the caps took 15 - 30 minutes each on the south
sides of the foundations and up to two hours on the north sides of the foundations.
6.3.2 Inter-array cable pull-in
Figure 23. The enclosure cap removed from the bell mouth.
At each foundation location, C/S Pleijel began the operation by pulling the cable through the
j-tube of the foundation, first, feeding the cable from the bell-mouth underwater up through
the shaft and out of the foundation top. The other end of the cable was floated towards the
second foundation, until it got within 30 - 40 meters from it, before the cable was pulled
through that second foundation, figure 24.
26 (30)