Mainz Installs 220-Metre Pipeline Under the Rhine Using Innovative Drilling

A major infrastructure project is set to begin in Mainz, where a new 220-metre supply and wastewater pipeline will be installed beneath the Rhine. The work, scheduled to start on 11 May, marks the first time Wirtschaftsbetrieb Mainz will use horizontal directional drilling for such an installation. The current pipeline, which connects the Ingelheimer Aue area near Gassnerallee to the sewer network at Mombacher Kreisel, has suffered partial damage. Instead of a costly full renovation, authorities have opted for a complete replacement. The new pipeline will have a diameter of 71 centimetres and will be laid up to ten metres beneath the riverbed for stability.

To enhance durability, the pipeline will be encased in a protective sleeve. This design choice aims to increase resistance to potential damage while simplifying future maintenance. The installation process involves horizontal directional drilling—a method that includes drilling a pilot bore, widening it, and then pulling the pipeline through the enlarged channel. Construction is expected to wrap up by the end of August 2026, ensuring a long-term solution for the city’s wastewater management needs.

The project will provide a modern, resilient connection between Ingelheimer Aue and Mombacher Kreisel. Once completed, the new pipeline will improve reliability and reduce the need for frequent repairs. Work begins next month, with completion targeted for late summer 2026.