Deep Dig-It trencher at work for TenneT

09.03.2020

The Hollandse Kust (South) offshore wind area in the Dutch North Sea is located 22 kilometres off the coast of the Dutch province of Zuid-Holland. TSCNET shareholder TenneT is responsible for connecting the wind farms under construction there via two corresponding offshore platforms to the onshore high-voltage substation in the industry and port area of Maasvlakte, from where the green electricity is transmitted further to the Randstad 380kV South Ring power line in the Dutch Randstad region, the most densely populated area in Europe, and further.

But there is a major challenge to be met by the Dutch-German transmission system operator (TSO): On the first ten kilometres of the offshore route, the four submarine cables to be laid are crossing the entrance to Europe’s busiest cargo port, the port of Rotterdam. To pass through the busy Rotterdam-Maasmond shipping lane, the cables here must be buried more than 5 metres deep into the seabed. For this specific job, the Dutch maritime contracting company Van Oord designed and built the Deep Dig-It trencher, a gigantic remote-controlled trencher.

Last Friday, final tests were carried out in the Aleksiahaven of Maasvlakte in preparation for the actual laying of the submarine cables in July. The innovative device is a so-called Tracked Remotely Operated Vehicle, which drives unmanned over the seabed, creates a deep trench for the cables, inserts the cables and closes the trench again. The Deep Dig-It is the largest and most powerful machine in its class. The trencher weighs 125 tonnes, is more than 17 metres long, well over 8 metres high and 11 metres wide. This makes it possible to bury cables in very hard ground, while the burial depth that can be achieved with the Deep Dig-It is well over 5 metres.

TenneT employs the powerful Deep Dig-It trencher to connect the Hollandse Kust (South) wind farms to the onshore grid (picture: Van Oord nv)

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