SWECO to plan expansion of the world’s largest underground wastewater treatment plant

The Henriksdal wastewater treatment plant in Stockholm, the world’s largest underground facility of this type, is to become even larger. SWECO has been commissioned by the Stockholm Water Company to plan and design the relocation of plant operations to underground caverns.

At present around 90 per cent of the plant is enclosed within rock caverns, and the remaining 10 per cent will now be moved inside in order to reduce traffic and unpleasant odours. This will also make it possible to build additional housing in the Henriksdal Harbour, Danvikstull and Lugnet areas. SWECO’s assignment includes design management and detail planning of the new mechanical equipment that will be installed inside the caverns. Among other things, the project will include blasting and excavation of 80,000 cubic meters of rock. ”We have carried out many planning and design assignments in connection with construction and rebuild projects, and have provided services to virtually all of the Swedish wastewater treatment plants over the years. This particular assignment will be something of a challenge since Sweden has few underground facilities in rock caverns,” says Per Managing Director of SWECO's Water and Environmental unit, SWECO VIAK. The total construction investment is estimated at over EUR 31.5 million, and will be co-funded by Stockholm Vatten and the City of Stockholm. SWECO’s contract is worth around EUR 315,000. The Henriksdal plant has a total area of 300,000 square meters and some 18 km of tunnels. The plant treats wastewater primarily from central and southern Stockholm and the municipalities of Nacka, Tyresö, Haninge and Huddinge.