Gampadels Unterstufe power station - general renovation, major construction work
Underground Mining Power station construction
Vorarlberger Kraftwerke AG commissioned the KGU consortium (Jäger Bau GmbH & HTB) with the renovation of the Gampadels power plant at the beginning of 2018. The refurbishment of the Bitschweil tunnel was carried out by the Jäger underground construction team as a sub-service for the consortium. The Gampadels power plant group, consisting of an upper and lower level, uses the hydropower potential of the Gampadelsbach stream from the Fischkalter reservoir to the point of its discharge into the Ill. The lower level (KGU) went into operation in 1925, and the upper secondary level (KGO) in 1989.
The existing 1,133 m supply tunnel underwent the following construction work in the course of the refurbishment of the Gampadels power station:
1) Demolition of the existing inner shell plus the excavation and shoring up of the mountain in two sub-areas with a total length of about 200 m.
2) New construction of the inner shell in the above-mentioned excavation zone using sulphate- and thaumasite-resistant lining material.
3) After completion of the extension work, injections were undertaken to bed the existing inner tunnel shell and in the area of the newly built inner shell.
The project was completed in March 2019 after a construction period of one year.
Key technical data for the refurbishment:
Existing cross-section (width/height) 1.20 to 1.40 m/1.60 to 1.70 m
Existing cross-sectional area 2.10 m²
Tunnel length 1,132.94 m
Cross-section after refurbishment 1.40 m/2.03 m
Cross-sectional area of new construction 2.60 m²
Total weight of demolished/excavated material 2,200 tonnes
Installed inner shell concrete 450 m³
Concrete for the floor 62 m³
Total length of injection bores 1,275 m
Total injection quantity 335,000 litres
Total length of discharge bores 457 m
Number of IBO anchors installed in the refurbishment area 32 pcs