New wastewater treatment plant to Blominmäki

​​​We are building a new wastewater treatment plant in Espoo’s Blominmäki bedrock. The caves to be excavated underground will host the wastewater treatment basins and the majority of other facilities.


 The above illustration shows the aboveground facilities of the Blominmäki treatment plant. Actual water treatment will take place underground. The aboveground structures include an administration and repair shop building, a building for sludge drying and power plant, upper parts of digestion silos, buildings for gas treatment, biogas storages, a garage, an exhaust air pipe and several other smaller buildings in the upper part of vertical shafts in caves. Flammable substances, such as methanol and fuel oil, will be stored above ground.

The abobe map shows where the Blominmäki treatment plant is located.

The new treatment plant will replace the current Suomenoja wastewater treatment plant. The capacity of the Suomenoja treatment plant is no longer sufficient to treat the entire area’s wastewater because the population and expectations for intensified wastewater treatment increase. After its completion in 2022, the treatment plant will process the wastewater of 400,000 residents from
  • Espoo and Kauniainen
  • Kirkkonummi
  • Siuntio
  • Western Vantaa.

The underground facilities of the treatment plant can be eventually expanded to cater for the wastewater of over a million residents, and so the new location of the treatment plant offers facilities for at least hundred years.

​By 2040, it is estimated that 150,000 m3 of wastewater will flow through the new treatment plant daily. The volume exceeds the current volume of wastewater flowing to the Suomenoja treatment plant by about half.

New wastewater treatment plant in Blominmäki - brochure