3.2 million cubic meters of concrete are to be cast for the Fehmarn Tunnel. For this, approximately 1,360,000 cubic meters of water will be needed. A significant portion of that water – 450,000 cubic meters – will come from Lolland’s groundwater reserves. However, when the tunnel is finished, and the element factory continues to operate, Lolland will no longer be able to supply groundwater.
In the future, the factory will have to cast concrete using technical water. This refers to water that has been treated to some extent. What kind of water that will be has not yet been determined.
– We are considering wastewater, seawater, and freshwater/surface water. It hasn’t been decided which direction we will take.
This was stated by Oliver Ries, team leader of the environmental department at Sund & Bælt, when Erhvervsfyrtårn Femern recently held a conference on sustainable construction of mega-infrastructure such as the Fehmarn connection.
Water on the roof
Together with Lolland Municipality and Lolland Forsyning, Sund & Bælt is working to resolve the issue of technical water for the factory. But securing enough technical water doesn’t have to be a problem, asserted Per Goltermann, a professor at DTU who specializes in concrete and structures.
– The concrete plant for the Fehmarn project uses 438,000 cubic meters of water. Do you know how much water lands on the roof of the factory during the construction period? 450,000 cubic meters. They wouldn’t have needed to draw so much from the tap if they had been collecting it throughout the construction and ensured there were no algae, he said.
However, he added a caveat to FemernReport:
– The problem is always storing such large quantities and being able to guarantee supply security – things that, in practice, made it impossible to do this on the tunnel project.
Drinking water is the easy solution
Ulrik Hindsberger, director of the Pipe Center at the Danish Technological Institute, confirmed that it could be a viable solution.
– There is a growing demand for water, and there’s no reason to use groundwater in industry. If you use technical water, it requires a thorough assessment of its quality, but rainwater that falls on a roof is fairly clean, he said.
– There’s no issue with supplying it if you think a bit outside the box. But we’ve been used to having super-cheap drinking water, and the easiest thing for a manufacturer is to say, ‘it has to be drinking water,’ because then it’s controlled. But when the facilities are in place, you can treat it for 20-25 kroner per cubic meter, Per Goltermann added.
He also mentioned that there are other ways to source technical water for the factory.
– If there’s two meters of sand, you can install drainage pipes and pump some of it up. You can also treat surface water, and I’ve heard there’s plenty here on Lolland. And at worst, you could desalinate seawater, he said, referring to the fact that this is an expensive and energy-intensive solution.
