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Limmern Power Station Pressure Tunnel (Contract Section A2), Linthal 2015

The Kraftwerke Linth-Limmeren (KLL) situated in Linthal were built between 1957 and 1968. These power stations are enormously important for generating electricity in Switzerland for as storage plants they first and foremost produce invaluable peak energy should demand be particularly great. In other words their contribution towards ensuring that power consumption and production are maintained in balance is a decisive one. As the need for peak energy is constantly growing, the KLL are to be augmented in the form of an additional, efficient pump storage station (Project Linthal 2015), which is to have a pump rate and a turbine output of 1,000 MW. This scheme, which makes great sense in both energy-producing and economic terms, will ensure that the supply of energy
in northeast and central Switzerland is safeguarded for years to come. Construction work is divided
into three contract sections (A1, A2, A3). Mechanised driving has a decisive role to play for this
major project and will be applied for contract sections A1 (access tunnel) and A2 (pressure tunnel Limmern power station). The access tunnel (contract section A1) will be produced from Tierfehd to develop the machine and transformer cavern planned within the scope of the construction project for the new Limmern pimp storage power station between Limmernboden and Muttsee. This will be provided with a funicular railway to transport personnel and large and heavy machine components. The access tunnel will be altogether 4,036 m in length and leads from the Tierfehd portal at a height of roughly 814 m ASL to the cavern centre at a height of some 1,700 m ASL. The valley station cavern forms the starting point for the roughly 3,764 m inclined tunnel with a constant 24% gradient. A hard rock gripper TBM is planned for this contract section. The KLL are planning a further extension and a hike in performance for their facllities in the form of the Limmern pump storage power station (contract section A2). With their current facilities the KLL can generate some 340 MW turbine output.
Thanks to the Tierfehd recycling power station that was recently commissioned this has been increased to about 450 MW. Following the expansion programme the KLL will be able to attain a maximum output of some 1 ,450 MW. The Limmern power station is a pump storage plant located underground, which pumps water from the Limmernsee lake into the Muttsee located some 630 m higher and if required makes use of it to generate power. The facility serves to provide for ba lancing power, energy production and its storage. A hard rock gripper TBM is to be applied for constructing
the pressure tunnel connecting the Muttsee with the cavern centre. lt will excavate 2 x 1 ,065 m long tunnels with a diameter of 5.23 m.

  • Country: Switzerland
  • Region: Linthal
  • Tunnel Use: Utility
  • Type of Use: Hydopower scheme
  • Client: Kraftwerke Linth-Limmern AG
  • Contractor: Marti Tunnelbau AG
  • Construction method: closed
  • Excavation: Hardrock TBM
  • No. of tubes: 1
  • Total length: 2130 m (Pressure tunnel Lot A2)
  • Diameter: 5230 mm (TBM)