Excavation of a discharge channel for the new Mur-hydroelectric power station in Graz, Austria is now progressing well following installation of 100 props from Groundforce.
The new €80M (£70.6M) plant is being constructed by the TB Mur-Kraftwerk Porr-Granit consortium on behalf of Energie Steiermark and Holding Graz and is scheduled to be completed in 2019.
An essential part of the overall project is the installation of a new storage culvert constructed along the river wall which, as a continuation of an already existing discharge channel at high water, will absorb additional mixed water from the Graz sewer system and feed it to the sewage treatment plant. This is to prevent untreated sewage from reaching the river Mur as is often the case during periods of heavy rainfall.
The new storage culvert which will sit in the river bed with the roof below bed level, has a cross section 8m wide and 4m high, and will link the power plant to the existing sewerage treatment works.
To enable construction of the culvert, a cofferdam 10m wide by 7m deep had to be constructed. Using a combination of 15m-long steel sheet piles with conventional steel walers, supported by 100 MP150 Groundforce hydraulic props which have a maximum load capacity of around 150t. This solution ensured optimum protection for the workforce and limited the ingress of groundwater into the cofferdam.
Use of a proprietary propping system over the conventional approach of structural steel reduced the amount of materials used and also saved time on the construction programme.