WastewaterInfrastructure MAXIMA Sweden UrbanDrainage

Major wastewater tunnel procurement begins in southern Sweden

*New wastewater tunnels to serve future generations in southwestern Skåne. Source: GlobeNewsInfo*

Swedish regional water utility VA SYD has launched the procurement process for the tunnel and shaft works forming part of the MAXIMA wastewater treatment system. The project will create a new underground wastewater transfer network serving several municipalities in southwestern Skåne and conveying flows to the rebuilt Sjölunda wastewater treatment plant.

The procurement covers two major tunnel contracts: the Northern wastewater tunnel and the Southern wastewater tunnel. Contractors are being invited to apply for prequalification, with qualified bidders expected to receive tender documentation by the end of 2026. Contract awards are planned for late 2027, with construction scheduled to begin in 2028 and finish around 2032. The full MAXIMA system is expected to become operational by 2035.

Proposed tunnel corridors for the MAXIMA wastewater system connecting Malmö, Lund and the Sjölunda treatment plant. Source: My New Desk (image by Maxima)

The Northern wastewater tunnel will run from Källby in Lund to the Sjölunda wastewater treatment plant. It will be approximately 10 km long, with an internal diameter of around 3 m. The tunnel will be constructed at depths of about 25 m to 30 m below ground and will include four shafts, ranging from 15 m to 40 m deep. Its storage capacity is expected to reach approximately 80,000 m³.

The Southern wastewater tunnel will extend from Turbinen in central Malmö to the Sjölunda plant. This section will include a 5.5 km main tunnel with an internal diameter of approximately 5 m, supported by two connecting microtunnels with a combined length of 2.4 km. The southern system will include 11 shafts, including a large shaft near Sjölunda with a diameter of about 45 m to accommodate a new pumping station. Its storage capacity is expected to reach around 100,000 m³.

The tunnels will be bored at depths of 20 m to 35 m, allowing wastewater to flow by gravity toward the treatment plant. From there, a new pumping station will lift the wastewater into the treatment process.

The MAXIMA tunnel system is designed to support the long-term wastewater needs of the Malmö and Lund regions while improving resilience during heavy rainfall. In addition to transferring wastewater, the tunnels will provide temporary storage capacity, helping reduce the risk of sewer overflows and urban flooding during intense storm events.

This function is increasingly important as cities face population growth, ageing drainage infrastructure and more frequent extreme rainfall. Deep tunnel systems can relieve pressure on existing sewer networks by storing large volumes of water below ground until treatment capacity becomes available.

The project presents significant challenges. The works involve deep shafts, long tunnel drives, microtunnelling, gravity flow design, major pumping infrastructure and strict requirements for durability. The tunnels are designed for a technical service life of 100 years, placing strong emphasis on construction quality, lining performance, hydraulic reliability and long-term maintenance access.

The procurement strategy also reflects the complexity of the works. VA SYD is procuring the two contracts as one package, allowing contractors to bid for one or both sections, with the final award based on the best overall combination. The works will be delivered through design-build contracts in close collaboration with the client organisation.

The launch of procurement marks a major step toward delivering one of Sweden’s most important wastewater infrastructure upgrades. Once complete, MAXIMA will provide a more robust, sustainable and climate-resilient wastewater system for future generations in southwestern Skåne.

Sources: mynewsdesk.com, globenewsinfo.com, tunnelsandtunnelling.com, maxima.vasyd.se, ted.europa.eu