Posted on September 8, 2016
By Bert Visser, fairplay
On 21 August last year, the Rijkswaterstaat (part of the Dutch Ministry of Infrastructure and the Environment) awarded the ‘Zeetoegang IJmond’ project bcontract for the design, building, financing and maintenance (DBFM) of a new sea lock at Ijmuiden. The winner – Consortium OpenIJ – consists of BAM-PGGM, VolkerWessels and DIF.
The new lock will be part of the IJmuiden lock complex, which gives access to the North Sea Canal and the port of Amsterdam. At 500 m long, 70 m wide and 18 m deep, it will be the largest lock in the world.
It will replace the Noordersluis (Northern Lock), which is currently the largest in the IJmuiden lock complex. However, this lock is almost 100 years old and is reaching the end of its technical lifespan.
On top of that, it is too small to cope with modern vessels that continue to grow in size, particularly now that the Suez and Panama canals have been expanded.
The new lock will ensure that the port of Amsterdam remains accessible to the new generation of ships.
Consortium partners
Construction companies BAM and VolkerWessels will build the lock and each has partnered with a financial organisation to take care of the financing part of the contract, pension fund provider PGGM and fund management company DIF respectively. Together, they make up OpenIJ.
Having been awarded the DBFM contract, OpenIJ has finalised an EUR80 million cooperation agreement with BaggerIJ (consisting of Van Oord and Boskalis) to realise all the dredging and dry earthworks, as well as all revetment works on this project, including both the dismantling of existing shore constructions and the installation of new revetments.
In June 2016, IHS DPC visited the BaggerIJ office in IJmuiden and spoke with Lucien Nuijten of Van Oord, and Arjan Kroot of Boskalis.
As they explained, there are two important primary requirements for the project: neither the maritime nor the road traffic may be blocked at any time as a result of the construction activities.
The lock complex not only constitutes maritime access to the North Sea Canal, it also offers a road connection between the northern and southern parts of the community of Velsen, of which IJmuiden is a part.
In order to guarantee the continuity of maritime traffic, current navigation channels will need to be diverted, resulting in the need for large amounts of dry earth work and dredging to be carried out, mainly near the Middensluis (Middle Lock) which lies just south of the new one.
To provide enough capacity at the lock complex for local road traffic, OpenIJ and BaggerIJ have taken a highly unconventional decision – no construction traffic will make use of these roads in any way. That means all transport to and from the building site is by water.
Special ferries will be used for this purpose, with a logistics centre in Amsterdam. All transport to and from the construction site, such as the supply of building materials or the carrying off of waste and surplus materials, will take place from this centre by ferry and will be coordinated from there.
Starting the works
The first important part of the project – carried out by BaggerIJ – was the removal of a piece of land known as the ‘Zuidersluiseiland’ (Southern Lock peninsula). This needed to be removed to allow for the diversion of the navigation channel that leads to the eastern entrance of the Middle Lock. In its turn, the diversion was necessary to permit the new lock’s first construction activities to start on schedule on 7 July 2016.
This meant the removal of the ‘Zuidersluiseiland’ had to meet a tight strict deadline of 6 July.
Back in January 2016, BaggerIJ started the operation which, in the first instance, comprised remediation works and the dismantling of a sheet pile wall.
For a long time, the ‘Zuidersluiseiland’ has served as an area where lock gates were stored and maintained, and the peninsula was also the site of a service port. As a result, the area has become contaminated with all kinds of industrial waste products. So both ‘dry’ (above the water level) and ‘wet’ (below water) remediation had to be carried out.
The dry remediation amounted to some 20,000 m3 of material which was brought to Boskalis Environmental’s specialised soil-washing plant in Schiedam.
The wet part consisted of around 15,000 m3 of material that was dredged and brought on barges to the ‘Slufter’ – a large scale disposal facility in the port of Rotterdam – where the Ardea, Boskalis’ barge unloading suction dredger, deposited them.
During this phase, the crane vessels Anna Catherina and Parcival (belonging to Van Oord’s subsidiary Paans Van Oord) were deployed, the first for the remediation works and the second for the removal of the revetment. Once these works were completed, Van Oord’s new cutter suction dredger (CSD) Biesbosch (see IHS DPC June 2016) was brought in.
This CSD will continue to play a major role throughout the entire construction period of this project and will carry out several further specific tasks. Dredging the ‘Zuidersluiseiland’ – about 600,000 m3 of material in total – is just the first of these.
For this, BaggerIJ is using two other main pieces of equipment: the trailing suction hopper dredger (TSHD) HAM 317 and the spray pontoon HAM 1208.
Kroot and Nuijten explained the work method used by the trio of vessels for this operation:
- The Biesbosch, located at the eastern side of the lock complex (the canal side), dredges and pumps the material through a pipeline that includes a sunken section crossing the access to the Middensluis
- This pipeline ends north of Middensluis, on the sea side. Here it is attached to the spray pontoon HAM 1208
- This spray pontoon deposits the material in a temporary pit dredged just next to the western access channel to the Noordersluis
- The material is subsequently re-dredged from this pit by the HAM 317, which brings it to a designated storage site at sea, known as Q8G.
The dredging cycle of the HAM 317 is such that it more or less corresponds with the pace of the CSD Biesbosch, which means that the 50,000 m3 capacity temporary pit, is never completely filled up.
Progress
By mid-June this year, the Biesbosch completed its task at the ‘Middensluiseiland’ and the HAM 317 shifted its activities to this location to deepen the diverted channel to its required depth, an operation that represented another 200,000 m3 of dredged material.
Part of this was allowed to be relocated at sea, in a disposal site normally used for maintenance dredging. Non-permitted material was relocated in an underwater pit in the North Sea Canal, near the western sector of the port of Amsterdam.
As scheduled, on 6 July 2016, the diverted channel at the eastern site of the Middle Lock was ready for use by shipping traffic and the next day, Consortium OpenIJ could start the first activities for the actual new lock construction – the ramming of a sheet pile wall that will constitute the southern edge of the new lock’s building site.
Once this sheet pile wall is completed, BaggerIJ can start filling operations behind it, using the sand previously relocated at the storage site Q8G in the North Sea.
Next milestones
The next important milestone for Biesbosch is 17 March 2017. On that day, the CSD will be positioned in the spot where the future lock’s chamber will be dredged. Although actual dredging of this chamber will not start till March 2018, the Biesbosch needs to be brought in early as other lock construction activities will obstruct a later entry. So, the Biesbosch will have to remain idle for a year at this location.
Other dredging activities are scheduled for 2018 as part of the “Zeetoegang IJmond’ project, including dredging the tongue of land currently lying between the Middle and the Northern locks on the canal side, and a similar operation on the western (sea) side.
As Kroot and Nuijten explained, the project has several aspects that significantly add to its complexity.
First of all, the lock complex is part of the primary sea defence and this function may not be compromised, even for a moment, during the dredging and earth work operations. This entails careful planning of all dredging, digging and filling operations for every stage throughout the project’s duration.
Second, the soil composition in this area is highly heterogeneous, particularly with respect to the contamination levels; that makes planning of subsequent dredging and digging actions even more complex.
Finally, a large percentage of the soil found is at a substantial risk of fluidisation when subjected to digging or ramming. This poses a challenge to the engineers of both OpenIJ and BaggerIJ in order to guarantee the ground stability, particularly during the excavating and re-filling of the many construction pits that will be needed for the project, as well as during the ramming of sheet pile walls and foundation piles.
For this reason, an extensive monitoring system is being applied within the project area.
The entire build project is scheduled to be completed by the end of 2019, at which time BaggerIJ will have shifted some 4.5 million m3 of material, about 50% from dredging and the rest from dry earth works.
But work for both OpenIJ and BaggerIJ won’t finished at that point – the 26-year maintenance period will then start.
Source: Fairplay
