„Neeltje Jans“ is an artifical island which was constructed towards the end of the nineteen sixties. It was the construction side for the main elements of the storm surge barrier. Nowadays the info center of the complex is here.
After the North Sea Flood of 1953 it was decided to close off the Oosterschelde by means of a dam and barrier. The nine-kilometre-long Oosterscheldekering (kering meaning barrier) was initially designed, and partly built, as a closed dam, but after public protests, huge sluice-gate-type doors were installed in the remaining four kilometres. These doors are normally open, but can be closed under adverse weather conditions. In this way, the saltwater marine life behind the dam is preserved and fishing can continue, while the land behind the dam is safe from the water.
Alltogether the construction consists of 65 pilons (18 000 tons and 65m high each). Huge plates hang between each, they can be closed by hydraulic within an hour.
The pilons were built as a hollow body in a dry-dock and brought afloat in its position. To ensure a stable baseplate special synthetic mats were developed, filled with rocks and brought to the seabed. The pilons were lowered to the mats, filled with sand and weighed around with stones.
The construction was completed in 1986. It is constantly tested and supervised and up till now no transformation has been discovered.
The 66th pilon was built as a replacement if something would go wrong during the mounting on the seabed. Fortunately it wasn’t needed and serves now as a climbing wall.