By Ashley Karen
MAXIMA, named after an early Roman wastewater system, Cloaca Maxima (translated as ’Greatest Sewer’), is a €1bn wastewater project in Malmö, Sweden, which will see the construction of a new 5km-long wastewater tunnel together, with two shorter connection tunnels, 11 shafts, a central pumping plant and a treatment plant.
As expected, the project will be one of South Sweden’s most significant infrastructure projects.
Client VA SYD is due to submit its environmental application for the project by the end of May, with the authorization process taking about two years.
In the meantime, VA SYD is willing to talk to contractors regarding the project and how tenders might be procured. It has yet to determine how the project will be split up and what form of contract will be employed.
VA SYD program director, Gitte Isacsson, expressed: “It is about finding the right chemistry between the client and contractor and putting the risks where they can be best managed.”
She continued: “We are looking for companies that can work in cooperation, looking at solutions in a constructive and open-minded way.”
The area’s current sewage systems were constructed in the 1950s and are now over capacity, which means that there are frequent overflows of combined wastewater and stormwater into canals and the harbor, even after relatively small amounts of rainfall. Moreover, the population of this area, which is connected to Copenhagen by the Öresund Bridge, is rising quickly.
Magdalena Beck, representing the city of Malmö stated: “With the existing system, we are polluting our water and that needs to stop,”
“This is most of all about our children and their future.”
The central tunnel will be 5m in diameter and operate through Copenhagen and Bryozoan limestone. Swecohe, the client’s designer, with specialist Austrian tunnelling sub-consultant iC, is proposing that due to the high groundwater table and faulted rock, an earth pressure balance (EPB) TBM will be best for the position.
EPBs were employed to drive the twin tubes for Malmö’s City tunnel railway project. Gitte Isacsson who worked on the City tunnel project, claimed: “The two TBMs for the railway were completed in the same geological conditions, so we have a good reference project.”
She added: “We completed that one year ahead of schedule and €100m below budget.”
However, the two shorter tunnels, each 1km long and 2.2m in diameter, are said to be pipejacked. Pressurized pipes will carry water from the different municipalities through drop shafts, moving by gravity to the major 42m-diameter, 30m-deep shaft, where it will be pumped up to a new treatment plant.
As Gitte Isacsson argued, the treatment plant’s construction at Sjölunda will be a logistical challenge since the current treatment plant must stay completely operational throughout construction.
With the environmental application made, the next milestone will be the formal decision to go ahead with the project, anticipated at the end of 2023. As predicted, the new system should be operational by 2032.
