Cologne's wastewater system is to be relieved in the long term and operate more efficiently thanks to an investment of a century. In 2023, Stadtentwässerungsbetriebe Köln (StEB Köln), in collaboration with Züblin Spezialtiefbau GmbH, began construction of the new Rhine culvert. This wastewater pipeline transports the majority of the city's wastewater under the Rhine to the large sewage treatment plant in Cologne-Stammheim. After almost 100 years of service, the existing culvert can no longer be extended. The new culvert will increase the flow rate of the wastewater by a factor of 1.5 to 6,000 liters per second. Thanks to a hydraulic control system, the wastewater volume can be flexibly adapted to the capacities of the sewage treatment plant. Cameras and an inspection shaft also simplify the maintenance process for the pipes.
After the construction of the start, inspection and target shafts on the opposite sides of the Rhine, two culvert pipes will be laid 8 - 15 m below the river bed using the pipe jacking method and connected to the existing sewer system.
PohlCons FIBERNOX® V-ROD reinforcing bars made of glass fiber reinforced plastic were used in the construction of the bored piles and diaphragm walls. Thanks to their good machinability, they were the ideal choice for this, as the GRP-reinforced elements had to be drilled through during subsequent tunnel driving. The very high tensile strength of the reinforcement bars of over 1,000 N/mm² means that any wall loads are reliably transferred.
5,000 kg of GRP reinforcement was installed as straight rods with a diameter of up to 35 mm as well as curved rods as stirrups and continuous helical reinforcement.
Excavation of the construction pits and pipe jacking are scheduled to end in 2026. StEB Köln is targeting 2028 for the completion and commissioning of the new Rhine culvert.
