Municipal power plant Inn, Prutz/Ried
Civil Engineering Underground engineering
A consortium with Jäger Bau built the power house for the Inn municipal power plant.
The power plant was built on the upper River Inn, in the Swiss-Austrian border area. This building was the largest hydroelectric power plant to be built in the Alps for many years, and will generate over 400 gigawatt hours of electricity from hydropower annually after its completion in 2018.
The power house is the heart of the power plant and was built almost entirely underground; only 4.5 m of the building protrude above the ground. The bulk of the equipment - such as turbines and generators - was installed in the approximately 26-m-deep shaft of the power house.
The excavation of the main construction pit was carried out entirely underwater and required the removal of several hundred thousand cubic metres of rock. The power house was executed in solid construction, and about 25,000 m³ of concrete used.
The contract includes the following services:
Construction of the entire road system (approx. 1.5 km of mountain roads)
Construction of the deep excavation pit (depth of up to 15 m, over 10 m of which is in the groundwater flow of the Inn) using diaphragm walls and prestressing anchors
Construction of deep sealing bases (gel soles) and anchored underwater concrete bases (using divers)
Construction of the entire groundwater drainage system for the power house, open drainage combined with a dewatering well
Construction of the underwater channel as a twin-cell cross section from the power house through to the Inn (length 300 m, section 22 x 4.5 m) including groundwater drainage
Implementation of the environmental measures prescribed in the EIA procedure