Monitoring of a deep excavation for a new water treatment plant and spillway tunnel outlet adjacent to important Swiss railway line
Volume Title: ICASGE2025
Paper ID : 1045-ICASGE-FULL
Authors
Sisgeo SRL Italy
Abstract
Two wastewater treatment plants located near Zurich, Switzerland, are advanced in age and need complete renovation and capacity expansion to maintain performance. The two plants are therefore merged. The new, wastewater treatment plant will treat the wastewater of 78,000 inhabitants and industry from 2027 onwards.
In the event of extreme flooding of the river Sihl, located near Zurich, the damage to buildings in the city of Zurich could exceed 6 billion Swiss francs. The construction of a spillway tunnel will allow the flood peaks of the Sihlriver to be transferred to Lake Zurich from 2026 onwards. This will significantly reduce the risk of flooding in Zurich.
For both structures, the WWTP and the outlet of the spillway tunnel, deep excavation shafts are being built close to each other beneath to an important Swiss railway line, on steep terrain and directly adjacent to existing buildings.
Sisgeo supplied innovative instrumentation, comprising several types of in-place inclinometers (MD-profile, BH-profile for 12 boreholes) 30 load cells to control the tension of soil anchors, creating an innovative monitoring system. For data-acquisition, ‘Sisgeo OmniaLog’ and wireless ‘Sisgeo WRLog’ data loggers were installed, both with interfaces for data transmission to a Web platform for ‘real time’ data management.
The presentation describes the importance of geotechnical instrumentation, the challenges of this projects structural engineering, the usefulness of instruments for monitoring, and emphasises the importance of having an efficient system that can guarantee a high level of safety to geotechnical risks during the construction work.
In the event of extreme flooding of the river Sihl, located near Zurich, the damage to buildings in the city of Zurich could exceed 6 billion Swiss francs. The construction of a spillway tunnel will allow the flood peaks of the Sihlriver to be transferred to Lake Zurich from 2026 onwards. This will significantly reduce the risk of flooding in Zurich.
For both structures, the WWTP and the outlet of the spillway tunnel, deep excavation shafts are being built close to each other beneath to an important Swiss railway line, on steep terrain and directly adjacent to existing buildings.
Sisgeo supplied innovative instrumentation, comprising several types of in-place inclinometers (MD-profile, BH-profile for 12 boreholes) 30 load cells to control the tension of soil anchors, creating an innovative monitoring system. For data-acquisition, ‘Sisgeo OmniaLog’ and wireless ‘Sisgeo WRLog’ data loggers were installed, both with interfaces for data transmission to a Web platform for ‘real time’ data management.
The presentation describes the importance of geotechnical instrumentation, the challenges of this projects structural engineering, the usefulness of instruments for monitoring, and emphasises the importance of having an efficient system that can guarantee a high level of safety to geotechnical risks during the construction work.
Keywords
in-place inclinometer; geotechnical monitoring system; data management; geotechnical instrumentation; geotechnical risk mitigation; Waste water treatment plant; spillway tunnel; anchor load cell; Sisgeo OmniaLog; Sisgeo WRLog
Subjects