Renovation of a Sewer Main with 15 Tangential Shafts in Strasbourg

The project, coordinated by the Water and Sanitation Division of the Urban Community of Strasbourg, involved the renovation of an egg shaped main dimensioned 1,400 x 1,900 mm that functions as combined sewer for domestic and industrial effluents. 980 m DN 1500 CC-GRP pipe were lowered into a trench with a depth varying between 3 and 9 m. Over a stretch of 550 m the existing egg shaped structure was sliplined utilizing GRP NC Line panels with an internal dimension of 1230 x 1660 mm. The concept and implementation of mixed installation techniques for the project was particularly innovative and pragmatic. All pipe material was supplied by HOBAS. “We were looking for the best techno-economical compromise and this led us to selecting these techniques for this project. The performance of the 2 methods and the pipe material had to be taken into account while keeping environmental impacts to a minimum. Trenchless installation enabled the industrial roadway to remain open for use and us to comply with budget and safety considerations”, explains Marc Hunsinger, head of the CUS Water and Sanitation Networks department. This project was coordinated by a consortium where SMCE Réha was responsible for the trenchless section and EJL Alsace for the open-dig section.