Unique ‘Blockbuster’ crane to build block dam
The construction of Maasvlakte 2 is proceeding well. This month, the 120 millionth m3 of sand was sprayed on. This means that half of all the sand needed for the first phase of Maasvlakte 2 up to 2013 has been applied. The project is therefore well on schedule. The construction of the first quay wall began in February and the contractors’ consortium PUMA has started building the hard sea defences along the northwest side of the new land. Over the last few months, a peninsula stretching approximately 3km was sprayed on here. A unique crane, the ‘Blockbuster’, is currently under construction. It will be used to position large concrete blocks as part of these sea defences. In this way, the construction of Maasvlakte 2 is entering a new phase.
Virtually the whole of the new coastline has been sprayed on. For as long as possible, a gap will be kept open in the new sea defences so that the dredgers have free access to the area. On average, approximately eight of Boskalis and Van Oord’s trailing suction hopper dredgers are in operation for the project. Earlier this month, eleven trailing suction hopper dredgers applied 3.8 million m3 of sand in the area, in the space of one week: a new world record.
Monitoring effects on nature
Over the past few months, measurements have been carried out on a regular basis on the amount of silt in the North Sea and the possible impact of this on nature. After all, with the sand reclamation and sand spraying on Maasvlakte 2, extra sand and silt particles end up in the water. The quantity of particles in the water remains well within the EIR predictions. As yet, no effects on marine life have been observed. The total monitoring programme to measure such effects during the construction of Maasvlakte 2 carries a price tag of approximately €10 million.
Quay wall for container terminal
In February, construction of the quay wall for the first deep-sea container terminal on Maasvlakte 2, the one belonging to Rotterdam World Gateway (RWG), began. This quay wall is being built in the sprayed-on sand, using a 40-m diaphragm wall. Bit by bit, grabs dig a trench to this depth, whilst at the same time the liquid bentonite is pumped into the hole. This ensures that the sides of the trench do not collapse. The trench is then reinforced, after which the concrete is poured. While the latter is taking place, the bentonite is pumped out. Once the diaphragm wall is standing, it is anchored on the terminal side with so-called MV piles: a type of sloping pile. Afterwards, a floor is cast at ground level. Finally, the sand can be dredged away on the port side. Things are not at that stage yet though. At the moment, the work is still limited to the construction of the first section of the quay. The diaphragm wall technique for quay walls was tried out at the Euromax terminal. The construction of the quay wall for RWG is on schedule. The first phase of the deep-sea quay will have a length of 1000 m. In addition, there will be a 500-m quay for freight barges and feeders.
Block dam recycled
Maasvlakte 2 will get 3.5 km of hard sea defences on the northwest side, where the waves can be high and where there is limited space in connection with the proximity of the Maasgeul. These sea defences will be able to withstand such storms as occur once every 10,000 years and they consist of:
- a stony dune to a height of NAP (Amsterdam Ordnance Datum) + 14 m with a cobble beach: a body of sand with a thick covering layer of light rubble (20–135 mm);
- a block dam to a height of NAP (Amsterdam Ordnance Datum) + 2 m constructed on the slope of the stony dune.
The low block dam causes the waves to break and the stony dune only has to cope with a much reduced swell. The slope of the stony dune requires some maintenance, especially after heavy storms. The stony dune works in virtually the same way as a sandy dune. Maintenance in the form of beach suppletion will have to be carried out on the sandy dune if too much of the dune profile is washed away by the waves. With the combination of stony dune and block dam, the block dam ensures that maintenance work on the stony dune is kept to a minimum.
The existing Maasvlakte already has a block dam made of approximately 20,000 40-tonne concrete blocks. The blocks are 2.5 x 2.5 x 2.5 m. They are now being removed from the water one by one using a backhoe: a crane on a floating pontoon. The crane is fitted with a ripper and equipped with sonar so that it can clearly ‘see’ the blocks positioned under water. The blocks are temporarily stored on the sprayed-on sand and subsequently reused in the new sea defences. At present, 1000 blocks are lying there waiting for their second lease of life.
Stones from Norway
For the stony dune of the hard sea defences, 7 million tonnes of stone are needed. This stone comes primarily from Norway. Different sizes of stone are used (0.3-35 mm, 20-135 mm, 5-70 kg, 150-800 kg, 1 – 10 tonnes). The stone is imported by large bulk vessels and sorted and stored at a site on the Yangtzehaven. 1 million tonnes of stone have already arrived in the Yangtzehaven. From here, a so-called stone dumper (the HAM 602) laden with 2000 tonnes of stone sails to the slope of the new sea defences five times a day.
In order to position the 20,000 concrete blocks correctly, PUMA has developed a special crane that can move the blocks from the new sea defences to the right location. This Blockbuster can position the 40-tonne cubes up to 50m from the heart of the crane with up to 15-cm accuracy. The crane has a counterweight of 360 tonnes and moves on three double sets of caterpillar treads. Construction of the Blockbuster will be complete in May. The crane will start work at the end of June.
Meanwhile, a start has also been made on a number of so-called interface projects. These ensure that Maasvlakte 2 will be connected seamlessly to the existing port infrastructure. To this end, a start has been made, for example, on the construction of a viaduct over the future access road to Maasvlakte 2 near to the Distripark Maasvlakte. The road and rail hub near the bend in the N15 close to the Slufter is a complex project. A fly-over and a junction for road and rail will be built here. These alterations will start in the third quarter. A budget of approximately € 500 million has been earmarked for these interface projects.
A look ahead
All aspects of the construction of Maasvlakte 2 are on schedule. Now that a start has been made on building the quay wall for RWG and the hard sea defences, the next milestone is when the Blockbuster comes into operation at the end of June. In the first quarter of 2011, construction of the quay wall for the second container terminal, belonging to APMT, will begin. The last gap in the sea defences will be sealed in July 2012, after which a road and a railway will be built along the outside edge of Maasvlakte 2. When these are completed, a passage will be made through the Yangtzehaven to make Maasvlakte 2 accessible for ships from the existing Maasvlakte. In 2013, the first container vessel will be able to moor at the quay.