MAINTENANCE DREDGING-WORKS IN THE COASTAL MARINAS

Creating and maintaining sufficient draught in the Flemish coastal marinas of Nieuwpoort and Blankenberge and the marina docks of Ostend and Nieuwpoort is one of the core tasks of the Coastal Division.

In Nieuwpoort, Ostend and Blankenberge the Department carries out maintenance dredging-works every year. In Zeebrugge, this is done every three years. These works are carried out as much as possible outside of the sailing season so that the Coastal Division causes minimum disturbance for recreational navigation and seeks to maintain the various zones at the appropriate depth for the summer season. To that end, there is constructive cooperation with the marina operators. They clear the docks so the dredging works can be completed more quickly.

Dredging in the port channels is done using a trailing suction hopper dredger. This is an independently-powered sailing ship with an adjustable suction pipe that is trailed across the bottom during dredging. This pipe is fitted at the end with a drag head that works like a giant vacuum cleaner. Inside the ship, the suction pipe is connected to a pump that sucks up a mixture of sand and water and pumps it into the hold of the dredger. The heavier particles settle in the hold, while the remaining water flows overboard.

For dredging the docks, a cutter dredger is used. This allows for dredging to be carried out under the marina jetties too. The dredge spoil that is sucked up is pumped over into self-propelled containers that then transport the dredged materials to dumps at sea.

In the areas where sand is dredged, checks are carried out to see whether it can be immediately used again, for example to feed the dry beach or to reinforce the foreshore.