Western HVDC Link: Cable installation update, April 2016

[Update – the work described below has now been completed.  This notice remains as part of the historical record of notices issued for this project.  Please refer to the most recent notice for an up-to-date record of the notices presently in force for this project.  This can be accessed via the project description page here.]

Mariners are advised, further to the notice issued in March, that work on the installation of the second deep water cable of the Western HVDC Link in the Irish Sea is due to resume at the end of April 2016.

This installation campaign will take place over a distance of about 120km, starting in Liverpool Bay and finishing to the south of the Isle of Man.  A Notice to Mariners providing information about the campaign including the location of this campaign, the vessels involved, route coordinates and safety advice can be downloaded here.  A brief summary of the campaign is provided below.

Cable Installation Campaign 2: Programme

This cable laying Campaign will involve a pre-lay survey of the cable route, a pre-lay grapnel run, then the laying of the cable, and finally a post-lay survey.  All of this work will be carried out by the vessels Go Pegasus and Giulio Verne and is described below.  The work will be carried out between the following locations:-

  • Start: 53° 31.646’N 003° 33.464’W
  • Finish: 53° 54.900N 005° 01.332’W

The coordinates of the entire Campaign are listed in the Notice to Mariners.

Pre-Lay Survey and Pre-Lay Grapnel Run

In advance of the cable lay and burial operations, the vessel Go Pegasus carried out a survey along the route using a Remotely Operated underwater Vehicle (ROV) during March 2016.  This survey included a survey of the pre-lay mattresses that were installed at cable and pipeline crossings along the route during 2015.

After surveying the route, Go Pegasus carried out a Pre Lay Grapnel Run (PLGR).  This operation ensured that the cable route is clear from any obstructions that could hamper cable burial.  Sonar markers were installed at cable and pipeline crossings during the PLGR to ensure that the cable is layed across the mattresses at these locations.

Survey work: Campaign 5

During mid-April 2016, the Go Pegasus is scheduled to complete the pre-lay survey for the middle part of the cable route, to the west and south-west of the Isle of Man (cable KP 178 to KP231.5).  After completing this survey, the Go Pegasus will commence cable burial operations in Liverpool Bay.

Cable laying and burial

Cable laying and burial work will be carried out by the cable laying vessel Giulio Verne, accompanied by the vessel Go Pegasus.  During cable laying operations, the Go Pegasus will follow the Giulio Verne at a distance of approximately 500m, and will tow a cable burial plough, providing for simultaneous burial.

Exposed cable locations

The cable will not be buried where it crosses existing cables or pipelines, and also at locations where the seabed character prevents cable burial with the plough.  At crossing locations and other areas where the cable is exposed, guard vessels shall monitor the cable until appropriate post-lay protection can be carried out.  The cable crossings are all specified in the latest Notice to Mariners (available here).

Vessels are requested to pass at a safe speed and distance from these locations and fishing vessels are advised to remain a safe distance (approximately 1.5 nautical miles) from the areas identified to ensure the safety of the vessel and its crew.

Post Lay Survey

At the completion of the campaign a Post Lay Survey will be carried out by Go Pegasus using a ROV.  The sonar markers installed at the crossing points will be removed during this survey.

Vessel details

Details of the vessels involved in these operations, along with their present location can be found on MarineTraffic.com via the links below:-

Vessels will be monitoring VHF Channel 16 throughout the operation.

The vessels involved in this work will be restricted in their ability to manoeuvre and other vessels are reminded to navigate with caution in their vicinity and pay strict attention to instructions issued to them by navigation authorities.

Guard vessels

Guard vessels will be stationed as appropriate along the cable route during installation and burial to ensure the safety of marine users.  There are presently 4 guard vessels on station along the cable route.  The areas being covered by each guard vessel are specified in the notice to mariners.

Notices to Mariners

The Notices to Mariners currently issued for this project are:-

  • Deep Water Cable Installation (Campaign 2) – this is the notice described above.  It provides an update on progress during March 2016 and a reminder of plans for cable installation campaign 2, which is due to be carried out between April and June 2016.  The notice can be downloaded here.
  • Deep Water Cable Installation (Campaign 2) – this notice was issued in March 2016 and provides advance notice of the activities described above.  Cable installation campaign 2 is due to be carried out between April and June 2016.  The notice can be downloaded here.
  • Route clearance, Out of Service Cables – this notice advises of work being carried out at 7 locations along the cable route to remove out of service cables that would prevent the burial of the Western HVDC Link cable.  The notice can be downloaded here.  This work has now been completed.
  • Wet storage of cable – this notice advises of the surface laying of a 28km stretch of cable in temporary “wet storage” along part of the Western HVDC Link cable route.  The notice can be downloaded here .  This cable is still in place, and is due for recovery at the end of Deep Water Cable Installation Campaign 2.
  • Deep Water Cable Installation (Campaign 1) – this was carried out by the vessel Giulio Verne, starting in July 2015.  The most up to date Notice to Mariners can be downloaded here.  Further work is expected along this part of the cable route in June 2016.
  • Concrete mattressing – along the cable route concrete mattresses have been laid at crossings of existing cables and pipelines.  A notice to mariners about the mattressing campaign conducted earlier this year can be downloaded here.

If you have any queries about the Western Link project, please contact Jim Andrews, Fisheries Liaison Officer by e-mail or by phone on +44(0)7908-225865.

Posted in AWJ Updates, Fishery Liaison, Western High Voltage DC Link, Western Link Undersea Cable

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