By Lynda Myer
In order to converting a storage and run-of-river power plant to a pumped storage power plant, preparations for tunneling are under way in Germany.
Including construction of mined caverns, water reservoirs and tunnels, the shell of the power plant cavern, construction of two pressure shafts, as well as foundation engineering work, the Lot 2 contract for the project at the Rudolf Fettweis plant in Forbach, in the Black Forest, was granted to Porr in July last year.
According to Porr project manager Torsten Schmuck: “In order for the mining work to start on time, several challenges needed to be overcome. We have to plan and organise up to four parallel tunneling operations in a complex tunnel, shaft and cavern system. Occupational safety is also very important. We are therefore setting up a rescue team with our own construction site staff that can act safely and quickly in the event of danger on the mountain. The permits for residential and explosives storage facilities as well as water law permits also involve considerable effort.”
Using shotcrete and soil nails, Porr is securing a slope under the B462 federal road on the factory site (construction site 1), whereas the main access tunnel to the cavern is due to be constructed from this site.
Additionally, the safety nets and safety fences are being installed in the slope areas north and south of the rubble tunnel (construction site 2) and the material resulting from the work in the mountain will later be transported away through this tunnel.
The value of Porr’s contract is €98.3m (US$107m) and it is part of a €280m investment by EnBW Energie Baden-Württemberg. The heritage-protected Forbach run-of-river power plant was commissioned in 1914 and converting it to a pumped storage power plant will significantly increase its efficiency.
