A 471,000 cubic meter rock field was excavated near the center of Turku for construction of the Kakolanmäki Wastewater Treatment Plant. When completed, the wastewater treatment plant replaced five old treatment plants and also reduced the region’s effluent load to the sea by 30–50%.
The sludge separated during the treatment produces biogas, which is used for district heating. The Kakola Heat Pump Plant also uses the waste heat from the treated wastewater.
The adjacent, valuable old buildings housing the Kakola Prison, created challenges for the excavation. Design and construction of the wastewater treatment plant particularly considered the location in the urban environment and near our valuable archipelago.