english Climate balance in sewer rehabiliattion: Cologne leads the way

How can the sustainability of sewer rehabilitation measures be quantified? The Entwässerungsbetriebe of the City of Cologne can already provide comparatively concrete answers to this question.

"We put two students to work on the subject, who studied the data and checked all the procedures for their carbon footprint - from the use of vehicles to electricity consumption and materials," explains Caroline Körner, head of department for renovation and geodata management at Stadtentwässerungsbetriebe (StEB) Köln. The result: "We generate less CO2 in the entire year with our closed sewer renovation than with two small sewer construction measures." Each year, the StEB carries out renovation work on 80 kilometres of sewer.

SteB plans climate neutrality by 2030

Away from the figures, Körner emphasised the importance of sewer rehabilitation compared to new sewer construction at the VSB advisory day: "Sewer rehabilitation is sustainable in itself - we use the existing resources to the end". According to Körner, SteB wants to be climate neutral as early as 2030 - five years earlier than the city of Cologne is aiming for.

From the current point of view, there are not many possibilities to save even more CO2. "With the sewer rehabilitation, we are only a very small component in the overall process. Even if we were to make small changes to the material, this would not have a noticeable effect.

Worst-case scenario as a basis

Körner admitted that the results of the calculations are not yet available in detail for all procedures. "We started with a worst-case scenario and have made a lot of generalisations. We are still in the process of fine-tuning." It should be borne in mind, she says, that in addition to sewer rehabilitation with cured-in-place pipes, the City of Cologne pays for a large part of its remedial actions with repairs. "The manual repairs account for half of our carbon footprint. But you can see: If we have to drill a hole in the head, this has a completely different CO2 balance than injection," says Körner.

"Manufacturers are now under obligation"

In an interview with the RSV, the grid operator makes it clear that tasks now lie ahead for the entire industry: "Now the manufacturers of the systems are obliged to provide information about the materials and to make the transport chains visible." At the level of grid operators, she said, there is a clear trend for the carbon footprint to become an integral part of public procurement procedures - as is already the case in some countries abroad. "Just a few years ago, people thought that this would not be an issue for a long time. But now we know: It will happen quickly," says Körner.

This year, the RSV founded the Sustainability Working Group, which has set itself the goal of advancing the topic in terms of future developments.

Bildquelle: Oben: Adobe Stock

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