A2SEA Story: Coastal Challenges Borkum Riffgrund 1
For CT Offshore, planning Borkum Riffgrund 1 from a cabling installation point of view has required more than a little creativity. For A2SEA, getting to and from DONG Energy’s Borkum Riffgrund 1 wind farm development, located 45 km off the German coast, is pretty much a straight-lined round trip from the port of Esbjerg in Denmark, to the wind farm 260 km away. But for cabling experts CT Offshore, things get a little more complicated.
The transit challenge
If you asked the project team at CT Offshore, they would probably tell you that the kind of port they prefer is a single, not-too-far-away one that can be used for load-out, as a site office location, and as a shelter if the weather should turn particularly rough. For the Borkum Riffgrund 1 project, however, a port like that just couldn’t be found.
Instead, the company has had to establish multiple locations, spread over a wide area, to fulfill each of these important requirements. Why? Take, for example, the nature of the coastal area closest to the wind farm.
As with any offshore wind project, time is of the essence. But just 10 or so nautical miles from the farm are a number of islands of varying sizes, complicating access for large vessels to the sea beyond. Combined with tidal conditions that rival those of the UK, the route from the client’s site office at Nordeich to the location far out to sea would be a lengthy one, adding unwanted delay to each journey.
Despite the desirability of locating its own site office close to the DONG Energy’s site office at Nordeich, the extended transit time required CT Offshore to review its options, looking for a site office as close to the wind farm location as possible.
The most obvious choice, at least from a distance perspective, was the island of Borkum, a tourist paradise known for its tidelands and protected wildlife park. While it would demand extra sensitivity to local conditions, locating on Borkum would cut transit time by at least an hour each way. And it would remove restrictions that would have been imposed if the load-out port had been Nordeich, which places speed limits on vessels for the first (or last) 10 nautical miles of each trip.
Disturbing the peace
Deciding upon Borkum turned out to be the easy part. Setting up a site office and finding accommodation for more than 20 seafarers at a time was anything but easy. Apparently, a tourist-oriented island prefers not to mix its holidaymaking atmosphere with heavy construction workers on a mission. But where accommodation can’t be rented, it has to be built, and 25-30 containers were shipped in to build a fully equipped container village that could do the job – entirely without the holiday feeling. When extra riggers were added to the project, a suitable house was found and rented, too.
There’s no feasible load-out port near the wind farm either, forcing this part of operations to be conducted at Nordenham, approximately 120 km away. And the most suitable shelter port was in yet another location – at the Dutch port of Eemshaven, around 55 km from the wind farm.
“We’ve never had to set up such a diverse, spread-out range of locations on any project before,” says Hans Peter Johannsen, Project Management Director for CT Offshore and A2SEA. “Normally, the load-out port is in the same location as our site office, which has lots of advantages.”
Hans Peter Johannsen points out that, while there are many small fishing villages in the nearby coastal areas, there are no suitable ports with sufficient water depths to handle larger vessels. This, he explains, will be a challenge for future wind farm projects, too, whenever there are intensive periods of work with more than one or two projects being built simultaneously.
Naturally, crew logistics are more complicated, too. So CT Offshore has chartered two 10-person planes able to land on Borkum.
“The use of planes has been popular with our crew, because instead of having to rely on commercial flights, it means they can get home on the same day they sign off and vice versa,” says Hans Peter Johannsen. “That’s a plus, but there are also time and cost savings for us, too.”
“One of the biggest challenges was that it was the first project for A2SEA and CT Offshore working together at full scale in Germany,” he explains. “So we have had to do our homework regarding German legislation, work hard to find new sub-contractors and so on.”
With the nearest large centre, Bremen, comparatively far away, very few supplies – and qualified labour – are within easy reach of Borkum, so everything has to be brought to the site office.
“The supply chain is limited in Germany and it is difficult to find industry expertise on a tourist island like Borkum. In fact, we have a whole new package of subcontractors. But everything’s in place now and things are going very well.”