SELI has won a EUR23.7 million contract to build the Passirio hydroelectric plant in Bolzano province, including a bypass tunnel, a vertical penstock, a subhorizontal penstock, a piezometric pressure shaft, a turbine hall, and access adits. The bypass tunnel is 5,885 m long and the excavated cross section is 10.75 sq m. A TBM will be used. The penstock is approx. 218 m high, its inner diameter is 2.2 m and its outer diameter is 2.7 m. A subhorizontal penstock, to be excavated by traditional methods, is 366 m long, for an inner diameter of 2.2 m. The piezometric pressure shaft is 48 m high, for an outer diameter of 9 m and inner diameter of 8 m. The turbine hall is 11 m long x 8.5 m wide x 7 m high. The access adits for the TBM and the penstock are 51 m and 102 m long respectively. Traditional tunnelling methods will be employed.The geology will consist in majority of metamorphic sedimentary rocks and, to a lesser extent, metamorphic magmatic rock. Geologists expect to excavate in paragneiss and micaschists. Water ingress of 50 litres/sec is expected. Tunnelling of the bypass tunnel will be achieved by means of a Wirth double shield TBM, 3.7 m in diameter, belonging to SELI and previously used for the new Canale Viola scheme. The cutterhead will be equipped with 17" cutters, the maximum cutterhead thrust will be 5.280 kN, with a cutterhead speed of 0-14 rev/min and a cutterhead drive power of 1,120 kW (4 x 480 kW). Click here. Inside, the tunnel will be lined with precast segments produced by SELI. A SELI muck train will take the rock out of the tunnel. The TBM is scheduled to start its work on 9th February, 2007 for completion on 16th January, 2008. Visit www.selitunnel.com and www.wirth-europe.com 44/06.