By means of two horizontal directional drillings of 1,350 metres and 1,450 metres, Visser & Smit Hanab installed a 48" gas pipeline under the Western Scheldt (river, which flows directly into the North Sea) for the 'Nederlandse Gasunie'. In particular, the artificial island in the Western Scheldt where the 450 ton drill rig was set, is unique.
The gas pipeline is part of the nationwide expansion of the main 48" transport pipeline of Gasunie, the North-South Route. The Western Scheldt Crossing between Ossendrecht (NL) and Zelzate (B) is part of the Wijngaarden - Zelzate section. For this unique crossing Gasunie called upon the expertise of Visser & Smit Hanab.
To ensure the passage of ships, this crossing was effected by means of a horizontal directional drilling technique through the seabed. Visser & Smit Hanab executed the 48" crossing by means of two horizontal directional drillings which meet in the middle (MIM).
An embankment with sand enclosed by sheet piles created an artificial island in the middle of the Western Scheldt, which measures 90 metres by 30 metres. From here the 450 ton drill rig executed the two drillings. The first drilling, HDD Groot Buitenschoor, led from the island to the Western Scheldt East shore with a length of 1,450 metres. The second drilling, HDD Vaargeul, ran 1,350 metres to the West shore of the Western Scheldt. Two additional 8" drillings were executed to transport the
drilling fluids and cuttings. The two pipe strings were prepared and welded on both shores. It took an entire day to pull both pipelines into the drill hole.
The sections were connected on the artificial island. For this purpose a second cofferdam of approx 50 metres by 8 metres was constructed on the island. After connecting the sections, the work island was dismantled which returned the environment to its original state. The time frame in which this project was executed was
limited due to nature restrictions.
Click HERE to see a video about this project.