Bau von Entwässerungskanälen – Bau Regenüberlauf und Rohrvortrieb

The City of Aschaffenburg awarded a contract to SONNTAG Baugesellschaft mbH & Co. KG for €12.47 million on 13 July 2026 to rehabilitate and reorganize the "Schloßberg" drainage system north of Johannisburg Castle. The scope includes decommissioning existing storm overflow systems, constructing a new overflow at Am Schloßberg, and building supply, throttle, and outlet channels with multiple shaft and special structures extending to the Main River, using primarily closed-pipe construction (pipe jacking/microtunneling) for DN 1600 main pipes and open-trench methods for supplementary lines. The project involves extensive earthworks, shoring systems including boreholes and steel sheet piles, reinforced concrete structures, and surface restoration, with particular complexity arising from groundwater conditions, heritage protection constraints at the city wall, and challenging ground conditions.