De-watering at the Finne Tunnel, Germany - Design and construction of a deep well system of 4.5 km length in a hard rock aquifer [Wasserhaltung am Finnetunnel - Planung und Durchführung einer 4,5 km langen tiefbrunnen-wasserhaltung in einem festgesteinsaquifer]
Muhlenkamp M.,Ingenieurburo Heitfeld Schetelig GmbH IHS |
Heitfeld M.,Ingenieurburo Heitfeld Schetelig GmbH IHS |
Klunker J.,Ingenieurburo Heitfeld Schetelig GmbH IHS |
Korndorfer C.,Wayss and Freytag Ingenieurbau AG |
Schetelig K.,Ingenieurburo Heitfeld Schetelig GmbH IHS
Geotechnik | Year: 2010
For the purpose of groundwater control during construction of the Finnetunnel 176 wells were installed along a stretch of 4.5 km length. Two separate cones of depression were established during the operation of groundwater control measures as both tunnels were driven by tunnel boring machines advancing in different stages. Groundwater was pumped through collection pipes to a central water treatment plant, and was then either reinfiltrated into the bedrock or discharged into the receiving water course. Drawdown characteristics of the extraction wells during the desanding process and results of a trial run were documented and evaluated in detail; on this basis, extraction wells were categorized and the groundwater control section was divided into six homogeneous areas of distinctly different hydrogeological and hydraulic characteristics. As a result, operation of the extraction wells and subsequently the extent of the depression cones could be adjusted according to the advancement of the tunnel. Pump operation times and groundwater extraction volumes were considerably reduced, thereby significantly contributing to the protection of groundwater resources as part of the tunnel is located within a groundwater protection zone.