The new plant is being constructed by the TB Mur-Kraftwerk Porr-Granit consortium, on behalf of Energie Steiermark and Holding Graz AG, both of which were appointed after a pan-European invitation to companies to tender.
The first groundworks for the €80 million project started in early 2017 and completion is scheduled for 2019.
Power plant will supply about 20,000 households with clean energy
Once fully operational, the power plant will supply about 20,000 households with clean energy, significantly improving the self-sufficiency of the region of Styria. With regard to the climate objectives agreed with the EU in Paris, Energie Steiermark and Holding Graz AG also expect an annual saving of about 60,000 tonnes of carbon dioxide.
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 x 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 about 150 tonnes. This solution ensured optimum protection for the workforce and limited the ingress of groundwater into the cofferdam.
Nedim Cetin, general manager at Groundforce, explained that the site in Graz demonstrates the advantages of a Groundforce solution.
'The use of resources is significantly lower overall'
"We have delivered a total of 100 MP150 hydraulic props with accessories such as clamping pieces and various extensions. Initially, this seems to be a significant amount but, compared with the cost of materials when using a traditional steel solution, significantly less material is used. In other words, the use of resources is significantly lower overall. And, of course, that is reflected in the calculation of the final costs," he said.
“There are also time advantages to using this system as the props are easily installed using a crane or excavator, aligned and then clamped hydraulically with the supplied shoring pump. This eliminates time-consuming re-lining and welding.
"While welds on steel columns have to be laboriously removed, with the Groundforce system you simply open a valve holding pressure released and the support can be lifted out of the supported area. It can then be used again at the new position and braced.
"Movable hydraulic units and various extensions and adaptors make the system even more flexible and offer countless additional options, such as angled and vertical supports. All in all, therefore, compared with the steel structure, significantly less material needs to be stored which can then be installed and removed in a considerably shorter time."
Convinced of the advantages of hydraulic bracing
Michael Metz, specialist in hydraulic engineering at Porr Bau GmbH and project manager of the ARGE TB Mur power plant in Graz, is convinced of the advantages of hydraulic bracing and said: "We are really pleased to be working with Groundforce. This type of excavation propping system is really unique. The handling of the props is very straightforward after a short instruction and works without any problems.”
Nedim Cetin said: "We are very pleased that, following our involvement on the Mur Power plant, we have had the opportunity to work with another internationally renowned client where the advantages of our system have saved time and costs. Looking forward, and building on our success in Germany, we are confident we will be able to further expand our services into neighbouring countries."
