LIGHTWEIGHT MATERIALS :
The water barrier will float upwards as a result of the rising water level in the harbours. This water will fill the steel container holding the dam. The dam is made from a light weight plastic, with a steel cover. The incoming water will push up the dam.
The dam will be incorporated into the road surface surrounding the historical harbour (approximately 60 metres of the Turfwal and some 115 metres of the Oude Schans). The embankment lining the new harbour (Kerkemaat) is raised 60 centimetres; this elevation will hold the dam (about 160 metres). The park on the south side of the new harbour (Weikamp) will be redesigned, in order to fulfil its water containing function. There will be no new water barrier at the other length of the marina (Havendijk). This will remain ‘outside the dam’. The buildings there have been built to withstand high water.
HIGH WATER PROTECTION PROGRAMME :
As a result of the construction of the floating dam, the water barrier at Spakenburg will meet the current requirements, to withstand water levels that occur during north-western storms at wind force 12. This is the requirement that all dams alongside the Zuidelijke Randmeren and the Eem must meet. Because these dams protect a large area against high water levels, this construction is called the ‘primary water barrier’, and the requirements for these barriers have been determined by the State. The construction of the floating dam is funded by the national High Water Protection Programme, a cooperative body of the Dutch water boards and the Department of Waterways and Public Works.
EXAMPLE FOR OTHER CITIES :
The technique is supplied by the Belgian company Aggéres. Although the technique has been used before, on different locations worldwide, the Spakenburg project will be the first time it is constructed at such a large scale and as part of the primary water barrier. This will make this a good example for other historical city centres in the Netherlands, such as Dordrecht.