Crown Bridges alliance, Helsinki
We construct multiple works for Stockholm Vatten, tunnels and the interior of the tunnels, equipment and systems. The operation of the existing plant will be ongoing throughout the construction period.
Stockholm is one of Europe's fastest growing cities, and with a steady population increase, it also imposes greater demands for water purification, while higher demands for cleaner water are imposed by the Baltic Sea Action Plan and the EU Environmental Directive. To cope with future wastewater treatment needs, the system needs to be renovated to maintain the water quality in Lake Malar and the Baltic Sea.
In light of this, Stockholm Vatten AB has decided to renovate the wastewater treatment plant in Henriksdal to accommodate future needs and environmental requirements. Stockholm's wastewater treatment thus urgently needs to be renewed. Henriksdal is one of the world’s largest wastewater treatment plants located inside rock.
We constructed a 400 metre long access tunnel for Stockholm Vatten in order to renovate the water basins for their future capacity improvements. The project is part of the groundwork for upgrading the treatment plant. The access tunnel was blasted beneath the plant's water basins and subsequently renovated with the aim of enhancing the capacity increase.
The construction of the tunnel was a complex infrastructure project because it took place in a vibration-sensitive environment. In addition to the plant's staff, all pumps and pipes in the vicinity, which includes residential areas, a protected historical burial site, day-care and schools must also be taken into account. This kind of work requires thorough risk analyses and the right knowledge of the work.
The access tunnel project started in January 2016 and was completed according to schedule in the summer of 2016. The rebuilding and capacity improvement of the Henriksdal wastewater treatment plant is expected to be completed in 2025. The initiative means above all that the water in the Lake Malar will be even cleaner and there will be fewer contaminants discharged into the Baltic Sea.
In February 2019 we started the interior works of the tunnel that will be the basis of the new wastewater treatment technology in the plant. YIT will also renovate and improve capacity of the entire sludge treatment process. The largest part of the contract includes the construction of a new sludge separation building including auxiliary equipment.
The contractalso covers earth works, concrete work, rock engineering of the plant as well as installation work for underground wastewater systems. The work will be completed in December 2023. The operation of the existing plant will be ongoing throughout the construction period.
In January 2020 we began E2 tunnel works as part of the development of Henriksdal wastewater treatment plant. The new contract covers tunneling works, concrete works, rock engineering for pumping stations and installation of pumping stations and pipelines. The main tunnel runs under the urban area between Bromma and Sickla in Stockholm and it will be approximately 14 kilometers long. YIT will construct 7.7 kilometers of the tunnel.