The construction of Maasvlakte 2 requires a gigantic volume of sand. In 2008, the section of the sea where Maasvlakte 2 is presently emerging was still some 17 m deep. Today, the new land lies over 5 m above New Amsterdam Water Level (NAP). The first phase of construction requires 240 million m³ of sand. Most of this sand comes from the North Sea. Research conducted in connection with the Environmental Impact Assessment showed that a sand extraction area some 12 km off the coast was the best option. The relatively short sailing distance to the construction site results in considerable energy savings, which in turn reduce the emission of harmful substances.
Of the 240 million m³ of sand required, 200 million m³ will be obtained from the sand extraction area. The remaining sand will be gained when the Yangtzehaven is deepened and cut through, the new port basins are dredged and during other projects in the existing port areas, such as the construction of the LNG Terminal. From 2012 on, the Yangtzehaven will form the access channel to Maasvlakte 2.
The sand is dredged up in the sand extraction area by trailing suction hopper dredgers. These sea-going dredging vessels can transport an average of 15,000 m³ of sand at a time. The ships use large suction tubes to suck the sand from the sea floor. The sand-water slurry ends up in the hold of the ship, called the bin. The water drains off again via an overflow. Hauling up one load of sand takes approximately one hour.
After this, the trailing suction hopper dredger sails to its destination. Depending on the depth of the site where the sand needs to be deposited, there are three methods to unload the sand. If the water is deep enough, the sand can be dumped via the bottom of the ship’s hull. This is also called ‘klappen’ in Dutch.
In areas where there is less depth because the new land is slowly rising from the seabed, the sand is sprayed onto the fill site using a gigantic nozzle fitted on the bow of the vessel. To allow for this, the sand in the bin must first be mixed with water again. Due to the arc of slurry projected by the nozzle, this method is also called rainbowing.
If the site has also become too shallow for rainbowing, the sand can be transported to the desired location via a floating pipeline. The pipeline is connected to the front of the trailing suction hopper dredger, after which the sand-water slurry can be pumped to the fill site. This method is called shore pumping.
To round off the first phase of Maasvlakte 2 on time, the dredgers need to extract some 200 million m³ of sand at sea from the start of the project. In the period 2009-2011, this equals over 13,000 full trailing suction hopper dredgers.