Helsinki’s stormwater filtration unit
Urban floods are identified as one of Helsinki’s most important climate hazards. Coupled with population growth and densifying urban structure, flood risk is likely to increase significantly. Apart from problems arising from the water being in the wrong place at the wrong moment, the poor quality of stormwater is a serious issue for the receiving water bodies. In the downtown Helsinki, the stormwater is discharged to the Gulf of Finland which is already suffering from excess nutrient load and other pollutants causing many harmful impacts in the ecosystem and reducing the recreational value. However, stormwater management requires space, which is very limited in the city. To meet this challenge, the City of Helsinki is testing a new nature-based solution in Taivallahti area, close to the city centre. The stormwater will be lead through a stormwater filtration unit to be purified before being discharged to the Gulf of Finland. The filtration unit will reduce the concentrations of solid substances, litter and different harmful substances such as microplastics. The pilot has been developed by by Olli Hakala from WSP Finland and Aalto University and it will be implemented in the Smart & Clean Stormwater project. The project has received funding from the Helsinki-Uusimaa Regional Council.
The filtration unit will be built in autumn 2018 and its schedule follows the construction of the separate sewage piping in Mechelininkatu and Eteläinen Hesperiankatu. The filtration unit will be located at an outfall of a stormwater pipe that gathers stormwater from heavily trafficked roads. Depending on the rain event, the filtration unit will capture part of the stormwater which would otherwise be discharged to the sea without a treatment.
Technology validated in relevant environment.
Fidelity of breadboard technology increases significantly. The basic technological components are integrated with reasonably realistic supporting elements so they can be tested in a simulated environment. Examples include “high-fidelity” laboratory integration of components.
Fidelity of breadboard technology increases significantly. The basic technological components are integrated with reasonably realistic supporting elements so they can be tested in a simulated environment. Examples include “high-fidelity” laboratory integration of components.
The innovation has been validated in lab: a prototype was built and flow measurements were taken. Different filter materials have been tested in another project by VTT. The filtration unit will be built in autumn 2018 and monitoring will be set up late 2018.
How does it work?
Objective of Helsinki’s stormwater filtration unit is to clean stormwater mechanically without input of external energy. The purification process is based on sedimentation (detention basin) and filtration.
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