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Gotthard Base Tunnel North

Water treatment and drainage during con­struc­tion phase

Both drives for the 7.8 km Erstfeld section of the Gotthard Base Tunnel produced water flows. To meet the conditions for discharge into the River Reuss, this water first had to be treated. The quantity of water ingress fluctuated widely depending on tunneling method and geology. Driving into water-bearing fissures resulted in high short-term peaks. Some of the water exhibited high pH values and fluctuating concentrations of undissolved material with varying particle sizes. The tunneling operations led to contamination with mineral oils and greases while blasting added traces of nitrite and ammonium. In some cases, geological factors also resulted in contamination of the tunnel water with sulfates, chlorides etc. The high water temperatures caused by the deep rock overburden in the base tunnel necessitated cooling of the water prior to discharge into the outfall. These widely fluctuating parameters imposed heavy demands on the systems and their operators.

Project period: 2003 – 2006
Services: Project management for Erstfeld section (as consortium member), plans for public display, main design, detailed design, tendering procedure, support during construction, site supervision

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