4 KM Penstock for power plant Greith
Hydropower plant Greith in the Upper Styrian district of Mürzzuschlag went on-line in September 2015. It was the third project realised by forest manager Dl Georg Wippel. With the three-jet Pelton turbine at the power house already installed, work on the final stages of the 4 km penstock along the pipe route was continuing at full swing.
Hydropower plant Greith was originally built as an isolated power station by Georg Wippel’s grandfather in 1955 to supply electrical energy to the family’s off-site forestry business.With the extensive rebuild of the facilities, things have changed dramatically. Most importantly, in addition to the forestry's self-supply the facility now also generates clean energy for the public grid. "Our original water rights would have been in place until 2045, but keeping the existing structures would have required several extensive renovations. So, yo put everything on a sensible economic basis, i went for a complete rebuild", explains the plant's operator, Georg Wippel.
EVERYTHING IS NEW AT HYDROPOWER PLANT GREITH
A brand new power house with a new machine unit was put up in a different location.
The two forebays were also redesigned and relocated about 40 m uphill. Still, the greatest effort by far was spent on extending the penstock, 4 km of which were rebuilt from scratch. The material used were SUPERLIT glass fibre reinforced plastic pipes by Upper Austrian pipework specialist Geotrade, which has its offices in Ried in the Riedmark. Glass fibre reinforced plastic pipes have excellent flow properties while being low-weight and also easy to install, thanks to the use of socket joints.SIX BROOK CROSSINGS
Immediate beneficiaries of this user-friendly system included the construction engineers from Haider & Co Hoch-und Tiefbau GmbH, who had install the pipework along the penstock route, which includes six brook crossings. Geotrade provided the required specially molded pipes and arches. T-pieces were integrated at regular distances of 1,000 metres, allowing mobile cameras to be inserted for inspection and maintenance purposes.
Using DN500 pipe sections, the team instaled the penstock over a total distance of 3,660m. The 360m DN400 supply pipes from the forebays were connected to the main pipe by means of a Y joint. The energy is generated using a three-jet Pelton turbine by Andritz Hydro, which is designed for an annual output of 1,425 MWh and a maximum design flow rate of 265 l/s, providing a maximum power of 353 kW.
 ZekHYDRO, May 2016, pages 50-51