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The City is currently building drains connecting the water treatment plants in Bonnevoie and Beggen. The works owner – the Service Canalisation (Sewer Department) – will undertake this work together with various internal and external service providers.
The total length of the sewers will be 6,150 metres, and the average depth will be 10-15 metres. A reinforced concrete pipe of DN 2,000 mm and internal protection with PE coating will be used. There will be nine access points to the site. Installation will be carried out through underground passages.
Commencement of work: February 2012
Planned duration: 95 months
Planned completion: 2019
Why do we need new drains?
Following the promulgation of new European directives in the early 1990s, Luxembourg City faced the following choice: either the Bonnevoie water treatment plant had to be upgraded to be able to treat nitrogen as well, or the plant had to be connected to the Beggen water treatment plant, resulting in the permanent shut-down of the Bonnevoie plant.
Following a technical and financial study, Luxembourg City opted for the latter alternative. This led to the idea of drains to transport waste water from the capital's southern neighbourhoods (Bonnevoie, Cents, Hamm, Pulvermühl and Gasperich) to the Beggen water treatment plant. This would also make it possible to collect water from Luxembourg City's other neighbourhoods and thus take the load off the existing drains.
There are further advantages still. A collector of this kind can also serve as a water retention basin and thus regulate the flow of water into the Beggen plant, or as an emergency basin in the event of a breakdown at the plant.
A few important dates
As with all of Luxembourg City's major construction projects, the project to build the drains connecting the Bonnevoie and Beggen water treatment plants had to go through several stages before construction actually began:
1993: technical and financial study on combining the two water treatment plants.
16 October 2002: the municipal council votes in favour of the draft proposal.
6 May 2004: the Chamber of Deputies votes in favour (Law of 6 May 2004).
26 June 2006: the municipal council votes in favour of the final plan. Applications for authorisation (Services Voirie, Eau, Environnement, CFL, "commodo" operating permit, etc.) Agreements with property owners.
Studies (project, hydraulic, risk, geology, insurance, materials, etc.)
9 December 2009: outcome of the bidding process is announced. Legal appeal against the decision.
9 January 2012: work begins.
2015: the first water begins to run to the Beggen water treatment plant
2017: all construction is likely to be completed by 2019.
The work is currently taking place in different locations simultaneously. This enables us to make rapid progress, optimise the use of our financial and human resources, and minimise disruption for our residents and visitors.
Main work-site challenge: sheer size of the project
Building such a huge drain network is an extraordinary, technical challenge. How can over six kilometres of pipes be built in the heart of the capital? What construction method should be used to ensure minimum disruption and maximum efficiency? What equipment should be used for the job?
Selection of a route
During the planning stage, our Service Canalisation considered a number of different factors, such as how the current water treatment plants operate and the connection points of the existing drains.
Other criteria, such as respect for private property, also played a role. The route that was finally chosen prioritises the use of public land and property, avoids disturbing vehicular traffic to the extent possible, and takes the geology of the terrain into account.
Pipe jacking and construction principles
Drains located at great depth are installed by underground pipe jacking (Unterirdischer Rohrvertrieb). This means that over the 6.15 km, the site's teams dig nine trenches. These trenches are approximately 15 metres deep, and 10–15 metres in diameter. They are secured by concrete piles along their sides, and then excavated.
The pipe jacking machine is set up inside the trenches and digs the tunnels into which the reinforced concrete pipes, with an internal diameter of 2 metres, are installed.
Progress to date
As the teams are working at several access points simultaneously, progress varies from one site to the next.
No. 1: The clean-out incorporated into the trench located at the Bonnevoie water treatment plant is nearly complete.
No. 3: The third trench is located in the Pétrusse Valley at "Schlittenhiwwel". The trench is complete. The temporary pumping station currently pumps water from the Bonnevoie water treatment plant to Beggen, to treat water from the Bonnevoie sewer lines at the Beggen plant even before the main collector is complete. The pipe jacking at the trench at 4, Rue Laurent Ménager has been successfully completed. Final construction of the inspection hole is nearly complete. The interior installations are under way.
No. 4: Hilco is in the process of removing its equipment from the site, as the pipe jacking between Trench 4 and Trench 5 is complete. Keren will install a crane in February 2018 in order to build the inspection hole in the pipe-jacking trench. The work to build the trench will be complete (if no problems arise) in late autumn 2018. At that time, the Service Voirie can do the final repaving.
No. 5: Trench No. 5 is located on Rue Laurent Ménager near the Gaston Diderich Stadium. The pipe-jacking machine has been removed from the trench, and there is currently minimal activity on site while awaiting the arrival of the jacked pipe from Rue Munschen Tesch.
No. 5: On Rue Munschen Tesch, Hilco is in the process of installing the machines to begin pipe-jacking towards Trench 5 at the end of March. The pipe-jacking work is expected to continue until November 2018.
No. 7: The work is complete. All that remains to do is to repave Rue Raspert, which will be done as soon as weather conditions permit.
Nos. 8/9/10: The trenches on Rue Pierre-Joseph Redouté (No. 8), on Rue de Bastogne (No. 9) and at the Beggen water treatment plant (No. 10) are complete. The section of the drain network joining these three trenches is also complete.
Contacts for this work site
VDL – Service Canalisation
VDL – Construction Mediators