ONE OF Europe's largest underground structures, a pumped storage scheme in Goldisthal, mid-Germany, is now half way through concreting after excavation finished earlier this year.
The scheme, just off the River Schwarza in the former eastern sector of Germany, should provide up to 1,060MW of extra power capacity during peak demand for the German grid.
Four reversible turbines will be powered by a 300m head of water from an artificial lake draining into a lower holding reservoir on the river. The same units will pump the water back up during low demand periods German consortium Walter Bau, Zublin, Heilit & Werner and Stuag began work on the underground complex in September 1997 with excavation of 1.3km long access adits to the two main chambers. The larger of these is the 138m long, 26m wide and 50m high machine cavern. A smaller 122m long, 15m wide and 17m high chamber will hold transformer units.
Two pressurized water tunnels from the upper reservoir, one 828m long and the other 817m, will also be built. The 7m diameter tunnels have 6.2m steel linings backfilled with concrete.
The underwater discharge tunnels are 9.6m excavated diameter running 279m and 275m respectively.
Some 60,000m 3structural concrete in the main hall and most of the lining concrete has been pumped using a Putzmeister pump unit. The scheme is for German utility Vereinigte Energiewerk and is due to start operations in late 2003.