Breakthrough has been achieved at the 3.5km Schrahnbach tunnel - part of Verbund's Limberg II hydro project in Austria - at a rate of up to 24m per day.
‘This could well be a new world record as tunnels are normally only excavated at a rate of 15m per day,’ said Herbert Schrofelbauer, chairman of the board of Verbund-Austrian Hydro Power. The fast breakthrough, which was achieved on the 12 January, was due to favourable rock properties.
A tunnel system with a length of 5.8km has been under construction since the beginning of March 2006. Schrahnbach is the third and last tunnel in the Alpine construction project. Approximately 300,000 tons of rock had to be removed during the excavation, with 40% used during the construction of Griesbach dam, built to protect the valley station of the Larchwand funicular from avalanches. A further 35% was used in the construction of access roads and 25% ended up in the rock beds opposite the station for the glacier railway.
Limberg II balancing and backup power plant, with an investment of approximately EUR 365M (US$473.8M), will be built underground and will more than double capacity of the Kaprun pumped storage plants from 353MW to 833MW.
When Limberg II is fully commissioned in March 2012, the Kaprun power project will provide approximately 10% of the grid capacity needed in Austria at peak consumption times.
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