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Lesotho, Mohale - ls/11

Water Transfer

  32 km-long, 4.1 m-diameter gravity-flow connection through basalts with occasional dolerite dykes between future Mohale reservoir and recently completed Katse reservoir using TBMs from each end and lined with concrete segments. Intake end will utilise existing 5.3 m-diameter Wirth TBM ex delivery tunnel north of previous contract and second TBM is 4.7 m NFM ex-Ecuador. Both machines are double-shielded. Hexagonal lining segments manufactured at site. Advances of 750 m/month per machine anticipated. High and low level intake tunnels 200 m long joining 100 m-deep gate shaft. Drill/blast operations at both ends to prepare TBM launch chambers. 800 m-long access adit at intake end for muck tippler and conveyor. Commenced February 1998 for completion January 2003. Design and construction supervision consultants: LHTP, a joint venture of Consult 4, Lahmeyer and Mott MacDonald. Contractors: joint venture of Hochtief, Concor and Impregilo. March 1999. Payments of $1.25 million bribes during 1988 by a number of participating companies to a former executive of the project have been traced and are under investigation by the Maseru court. Sept 1999.