Soft sea defence take shape at Maasvlakte 2
The sand dunes around the Maasvlakte 2 project are being planted with marram grass.
The Port of Rotterdam Authority in the Netherlands says around 190m cu/m of sand has now been put in place for the project to form new land which will be protected on its western side by some 6km of dunes.
Between February and the end of April 2011 contractor PUMA was due to be planting four kilometres on the seaward side of the dunes with marram grass, a project which will largely be done by hand. The marram grass will bind the sand of the new dunes, preventing erosion.
A total of 200,000 to 300,000 sq/m of dunes will be planted with marram grass. Eight to 10 people a day will perform the manual work. It is expected that the final two kilometres, including the stretch of dunes near the Slufter, will be planted in the autumn. When that work has been finished, the soft sea defences will contain around 1.5m marram plants.
Marram grass can withstand wind and salt spray. The roots can grow to a length of 6m to 9m and in this way will bind the sand in the dunes in place.
Marram can be planted in early spring or autumn. On flat areas or slight inclines a machine makes grooves in the ground. On steep slopes, this is done by hand, using a spade. The marram grass is then planted manually in the grooves and the base is pressed down with the foot.
The dunes are about 14m high and consist solely of sand. Most of the sand involved comes from a sand extraction area approximately 11km off the coast and is sprayed on by dredgers operated by contractors Boskalis and Van Oord. The dunes are then finished off and the dune top is created using dry equipment such as dumpers and diggers. As soon as the dunes are the right height and shape, they are planted with the marram grass.
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