240 million cubic metres of sand will be needed up to 2013 for the construction of the seawall and the first phase of the sites available for release. In the cutting through of the Yangtzehaven, deepening the new port basins, and from other projects in the port area, some 40 million cubic metres of sand will be extracted. This sand will be reused in Maasvlakte 2. The rest of the sand needed will come from a sand extraction area in the North Sea.
Sand, sand and more sand
240 million cubic metres of sand - that's a lot: more than 160 times De Kuip football stadium brimful of sand. A large trailing suction hopper dredger transports 18,000 cubic metres of sand. That means roughly 11,000 trips back and forth to the extraction area in the North Sea. To transport this much sand by land you would need 1,200 trucks, or 216,000 wheelbarrows.
Sustainable sand extraction
Extensive research has revealed on what locations in the sea sand extraction will have the least effect on sea life. Based on this, sand extraction a short voyage away from Maasvlakte 2 was opted for, thus minimising the environmental impact. The sand extraction is taking place outside the Voordelta coastal delta.
The effects of the sand extraction on the life on and in the seabed and on fish and silt are described in the Construction Environmental Impact Assessment. There are two clear effects: damage to seabed life and silt production.
At the extraction site, the seabed life disappears along with the sand. This seabed life recovers a few years after the sand extraction by recolonisation (natural return). During the extraction, the negative environmental effects are limited as far as possible by creating deep extraction pits, as deep as twenty metres under the seabed. By specifically digging deep rather than wide, the total area of temporarily disturbed seabed is reduced considerably.
In sand extraction, water with silt (clay particles) is sucked up too. The water and silt run back into the sea from the dredgers. The suspended silt particles cloud the water, so that less light penetrates. A possible result of this is that algae grow more slowly. Algae are food for snails and shellfish that in turn are food for birds and fish. Cloudiness can thus lead to less food for a number of species and possible disruption of the food chain. Suspended silt is however also a natural phenomenon. Every storm disturbs silt from the sea bottom and rivers continuously supply silt. Through the Straits of Dover too, ten to forty million tons of silt come annually into the North Sea. On the sand extraction site chosen, the concentration of silt in the seabed is relatively low. The expectation based on the Construction Environmental Impact Assessment is that the extraction will only have slight and temporary effects.
Monitoring sea-life quality
Before construction of Maasvlakte 2, the condition of the sea-life was mapped out. Reference measurements on the seabed took place in 2006 and 2008. Samples were taken from a large area at 300 places up to fifty kilometres off the coast between Schouwen and IJmuiden. In 2007, reference measurements were taken of juvenile (young, not yet fertile) fish and silt at one hundred other locations up to 30 kilometres off the coast between Walcheren and Den Helder.
Now that construction is fully underway, repeat measurements are being taken regularly, which are then compared to the reference ones. The measurements will continue until around ten years after the sand extraction is finished. In this way, it can be checked in practice whether the environmental effects described beforehand in the Construction Environmental Impact Assessment do or do not happen. Such an extensive scientific investigation into the effects of sand extraction on seabed life, both before and during dredging activities, has never before been carried out in the North Sea.