Mur power station, Graz

Work started immediately the contract was awarded: in January 2017, project teams began clearing the river banks and setting up construction site facilities. These included a gravel processing plant and a concrete mixing plant, containers for offices, foremen and site crews, and large machinery areas. Once this was done, the gas, water and electricity lines were relocated and diversions set up for the footpaths and cycle paths. At the same time, work began on the temporary diversion of the Mur itself, skirting the construction pit where the weir and sealing work would be done. The Mur was diverted right on schedule at the beginning of summer 2017 and as soon as the sealing work was completed, work could begin on building the power station.

Sealing activities for the upstream dams began while work continued in the central reservoir channel. According to the plans, the dams were to be sealed with membrane walls up to 30 m. However, since – for reasons that have not yet been resolved – this proved impossible, the majority of the sealing was completed using the jet grouting method. In parallel with the sealing work, the “Rudersdorf” riverside biotope was developed – an ecological mitigation zone comprising a 1.8ha riparian woodland with 7,000 trees and a stream running into the Mur. While one team was busy on the biotope, another project team was working on deepening the river bed, a scheme designed to maximise the effective drop height for the Mur water in the weir.

The river bed was deepened by an average of 2.5m using a backhoe excavator, and around 250,000m³ of spoil was transported to the gravel processing plant with articulated dump trucks and processed into various grain sizes for recycling. The majority of this material was used for concrete production for the weir and central reservoir channel. The weir construction work was running to schedule, and the two Kaplan turbines were installed and the Mur restored to its usual course in summer 2019. The power station started up in October 2019 and the 17.7 megawatt plant is now feeding 82 million kilowatt-hours of green energy into the grid each year, supplying the energy requirements of over 45,000 people in Styria’s capital city – or the consumption of over 20,000 electric cars – and reducing harmful emissions by over 60,000 tonnes of CO2.

The Covid-19 crisis caused minor delays to completion of the central reservoir channel and various project-related activities included in the tender that will transform the area around the power station into an attractive recreation zone for local residents. Completion is now scheduled for the end of 2020.