A wastewater tunnel beneath Malmö

A wastewater tunnel beneath the center of Malmö enables protection of the local water environment, addresses the challenges of population growth and an obsolete wastewater system – allowing more people to live and work here.

The planned wastewater tunnel from Turbinen in central Malmö to Sjölunda wastewater treatment plant is a 5.5 kilometres long main tunnel with two connecting micro-tunnels totalling 2.4 kilometres. The main tunnel will be drilled at a depth of 20–35 metres, and the wastewater will be transported by gravity to the wastewater treatment plant. There, a large new pumping station will pump the wastewater from a depth of 35 metres up to the treatment plant.

Main tunnel
Location: from Turbinen in Malmö to Sjölunda wastewater treatment plant
Length: 5.5 kilometres
Placing: 20–35 metres below ground
Internal diameter: 5 metres
Storage capacity: 100 000 cubic metres
Technical lifespan: 100 years

Microtunnels
Length: a total of 2.4 kilometres
Placing: 15–25 metres below ground 
Internal diameter: 2 metres

Sjölunda pumping station
Capacity: 10 cubic metres per second
Location: next to Sjölunda wastewater treatment plant, and will pump the wastewater from a depth of 35 metres up to the treatment plant

Shafts
Number: a total of 11 shafts along the tunnel route
Size: usually 4–15 metres in diameter but the shaft closest to Sjölunda is 45 metres in diameter for building the new pumping station
Depth: 18–37 metres down into the ground
Application: tunnelling, evacuation during the construction phase, connection of the existing pipe network, construction of a new pumping station and access for operation and maintenance

Benefiting population growth and the environment

A wastewater tunnel beneath Malmö replaces the existing pressurised sewer system (pipes and pumping stations) and facilitates urban development and population growth. The wastewater tunnel also reduces the risk of disruption and overflow discharge from the combined pipeline network.

The community and environmental benefits:

• Robust, long-term transfer of wastewater from Malmö to Sjölunda wastewater treat-ment plant with higher capacity to cope with population growth
• Greater opportunities for urban development of Malmö as the wastewater tunnel will be built deep underground
• Less need for service and maintenance, reducing the risk of disruption in Malmö
• Less discharge of pollution into Malmö's canals, the Malmö port area and the Öresund from the wastewater treatment system
• Lower risk of basement flooding near Malmö’s canals
• A storage function that will relieve pressure on Sjölunda wastewater treatment plant, enabling optimisation of the plant's functionality

Learn more
Overflow discharge occurs when the pipes are overloaded. Untreated water is then released into the sea, rivers and canals.
We explain more about overflow discharges here