This project, known as the New water supply Oslo Project, is the largest investment ever undertaken by the City of Oslo, with NOK 26,8 billion
The project consists of three main parts. The new water transfer that’s being constructed will cover a distance of 19 km between Holsfjorden and Huseby in Oslo, which will involve the removal of approximately 400,000 cubic meters of rock by two Tunnel Boring Machines (TBM). The project also consists of a new water treatment plant at Huseby and new water mains for the distribution of clean drinking water.
Skanska Norway AS, the main contractor of this works, called for the international expertise of both Sarens and Herrenknecht AG to install the two TBMs in the shafts. Sarens has chosen an HG250 hydraulic gantry system, capable of lifting up to 1,000 tons. The two machines (TBMs) will construct the 19 km tunnel from the new water source in Holsfjord to the new water treatment plant being constructed at Huseby.
Oslo's new water supply system will ensure access to second source of drinking water for the Norwegian capital, in the event that the existing source Maridalsvannet and the water treatment plant supplying 90% of its inhabitants will malfunction. The population growth is also expected to be substantial in the next two decades adding to the demand for drinking water. This project will require the construction of a 19 km subway pipeline between Holsfjord and Huseby using two tunnel boring machines, in which Sarens, world leader in heavy lifting, engineered transport and crane rental, has played a key role.
Herrenknecht AG, one of the construction companies commissioned by Skanska to carry out the excavation work for the construction of the water pipeline, decided to call on the expertise of Sarens for the installation of the two tunnel boring machines, each with a diameter of 5.2 meters, due to the minimal space available in the shafts, both in Lake Holsfjord and in what will be the new water treatment plant in Huseby.
In total, the new pipeline constructed by two tunnel boring machines is expected to move approximately 400 000 cubic meters of rock, the equivalent of filling more than 160 olympic swimming pools, with raw material.
This project, known as New water supply Oslo, is the largest investment ever undertaken by the City of Oslo, with NOK 26,8 billion, and is part of the operations led by the Agency for Water and Wasterwater services. The main objectives of this strategic initiative are to guarantee the quality of the Norwegian capital's drinking water, reducing the risk of drought or access restrictions, and providing an alternative water reserve to supply the current 690,000 inhabitants in the event of any contamination of the Maridalsvannet or Oset treatment plants, on which it currently depends.
Once on site, the Sarens engineering team decided to modify the installation process for the 20 parts required to operate each TBM. While cranes are normally used to move parts weighing up to 200 tons to the shafts and, once inside, rotate them as necessary for the assembly specialists to carry out their work, on this occasion Sarens’ team decided to use a hydraulic gantry system due to the minimum operating space.
The model used for this project, the HG250, offers a load capacity of up to 1000 tons, which brings greater maneuvering agility in narrow spaces, thus minimizing the impact on the work environment and in the daily life of the citizens living in the area by not requiring larger shafts, also reducing the time required to assemble and dismantle the TBMs.
According to Sindre Vandbakk, Key Account Manager at Sarens, "if working with heavy loads is always a challenge in itself, projects like this one, where the space available for work is practically minimal in just 12 weeks, is even more so. Fortunately, at Sarens we are able to respond to any of our clients' needs and adapt to the magnitude of any project and load thanks to our team and the versatility of our machinery".
Sarens has extensive international experience in the erection and installation of tunnel boring machines. Among others, the company has carried out large-scale projects in The Hague (The Netherlands), in the construction of new metro stations in Crétiel and Algiers (France), or in the project for the installation of a new railway line in Lodz (Poland).
About Sarens
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With more than 100 entities in 65 countries operating without borders, Sarens is an ideal partner for small to large-scale projects. Sarens currently employs 4,543 highly qualified professionals who are ready to serve the needs of any client worldwide and in all market sectors. https://www.sarens.com/