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Italy, Arezzo - it/11

Water Transfer

Three separate 4.24 m-diameter drives totalling 4.1 km using Lovat with chromium carbide plating on cutterhead face and rim to resist abrasion. 3.6 m i.d. honeycomb segments. Tunnels are Saccione (2.9 km), Tondo (1.7 km), San Firenze (1.4 km). Fourth tunnel at La Giostra will be 1 km long. Contractor: Ferrocemento Recchi Spa commencing tunnelling May, 1999 on two year programme. April 1999.Condotte d'Acqua purchased a 4.24 m-diameter single shield rock TBM from Lovat to construct the 2.5 km Castellaccio water diversion tunnel for irrigation, in Chiana valley in central Italy. The client is Ente Irriguo Umbro-Toscano. Boring through rock, the Lovat TBM model RMP167SE series 21700 is to erect a honeycomb type tunnel lining, consisting of prefabricated reinforced concrete segments, having an outside diameter of 4.1 m and an internal diameter of 3.6 m. One special design feature of the TBM is its ability to be assembled and disassembled internally within the tunnel. More specifically, the assembly and launch will be inside a tunnel chamber at the end of an existing tunnel. The disassembly will take place in a blind tunnel with no chamber, followed by the complete removal of the TBM through the tunnel. Arrival of the TBM on site expected for the end of April 2005. Visit www.lovat.com and www.condottespa.it 40/04.Condotte is close to completing the Castellaccio tunnel, which forms part of the primary water conveyance from Montedoglio dam to Valdichiana. The owner is Arezzo-based Ente Irriguo Umbro-Toscana. More than 50% of the 2.6 km-long circular tunnel is finished. Condotte took over the project from another contractor who failed to finish the job after boring 1.3 km of tunnel. 'Paoletta', a Lovat TBM model RMP167SE, is used. The excavated diameter is 4.25 m and the internal diameter is 3.6 m. Support and lining with prefabricated honeycomb segments. The assembly chamber of the TBM, at the junction with the section already built by the previous contractor, has been drilled and blasted and supported with steel ribs and shotcrete. The TBM will be pulled apart underground, without excavating an exit cavern.The tunnel alignment crosses Londa formations, made up of an irregular alternation of marls and silts, sometimes intercalated with banks of limestone and sandstone. The joints between the different components of the geological formation are often moderately altered and frequently filled with clayish material. Generally slight cover although its thickness may range at some spots 5 to 10 metres.Schoema locos and Palmieri muck cars for mucking-out. Cost of the project: EUR8 million. Click it/11. Visit www.condottespa.it, www.lovat.com, www.schoema-locos.de and www.palmierirocktools.com 16/06.