Co-ordinated by the Water and Sanitation Division of the Urban Community of Strasbourg and contracted to SMC Réha, the reconstruction of the sewer main for the Rhine Harbour the project involved the renovation of a 1,400 x 1,900 mm egg shaped main that functions as a combined sewer for domestic and industrial effluents.

Of the total 1,530 metres of main to be rehabilitated, sliplining was used over a stretch of 550 metres of the existing egg shaped structure, using HOBAS GRP NC Line panels with an internal dimension of 1,230 x 1,660 mm. Sliplining provided the most economical way of rehabilitating certain sections of the main.

“Trenchless installation enabled the industrial roadway to remain open for use and for us to comply with budget and safety considerations,” said Marc Husinger head of the CUS Water and Sanitation Networks Department.

As the sewer main had a curved section, panels of differing lengths varying from 1 to 2.35 metres were required for the relining. The 25 mm thick NC line walls were calculated to ensure the optimal performance of the new line which will transfer vertical loads, including ground and heavy industrial traffic, and withstand aggressive substance from agronomical industrial plants’ effluent, with pH levels rising from 1 to 10.

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When discussing the benefits of using Trenchless Technology on such a project, Laurent Gerber Managing Director of SMC Réha said “trenchless rehabilitation was a good alternative installation method that allowed us to keep existing trees and moreover ensured open access to the industries of Strasbourg’s harbour.

“The sliplining only required three access pits over the 550 metre stretch that was rehabilitated and therefore kept disruptions of a strongly frequented road to a minimum.”