The Lesotho Highlands Water Project (LHWP) is a multi-phased project intended to provide water to the Gauteng region of South Africa and to generate hydro-electricity for Lesotho. The project entails harnessing the waters of the Senqu/Orange River in the Lesotho highlands through the construction of a series of dams, for the mutual benefit of the two countries. Phase I of the project was completed in 2003 and inaugurated in 2004. Phase II is currently underway.
This phase comprises the construction of the Polihali Dam; an approximately 38km transfer tunnel to convey water from Polihali to Katse Dam; and all associated advance infrastructure.
SMEC South Africa, as a member of the Metsi a Senqu-Khubelu Consultants Joint Venture (MSKC) appointed by the Lesotho Highlands Development Authority (LHDA), is providing professional services for the design and construction supervision of the Polihali Transfer Tunnel.
Altogether, MSKC will carry out the design and construction supervision of approximately 8.3km of drill-and-blast tunnels, including intake tunnels, access adits, connector tunnels and outlet tunnels; approximately 34km of tunnel-boring-machine tunnels; approximately 230m of shaft sinking; a lake-tap outlet into the Katse reservoir; and all associated concrete work, access roads, site offices, storage /laydown areas and other related surface works and infrastructure.
“Training LHDA staff to operate and maintain the tunnel is part of the skills and technology transfer element of this contract”, states SMEC South Africa Project Director Chris Viljoen. “The contract also makes provision for the training of young professionals”.
Water from the LHWP is transferred in terms of the Treaty between Lesotho and South Africa, via the Katse reservoir, through a transfer tunnel and delivery tunnel, to the Ash River outfall between Clarens and Bethlehem in South Africa. Water flows from the Ash River into the Liebenbergsvlei, which joins the Wilge River near Frankfort before finally reaching the Vaal Dam in Gauteng, South Africa.
Phase II is expected to ensure another source of reliable water supply to South Africa that will meet the demands of the Gauteng region, increasing the current supply rate of 780 million m3 per annum from the LHWP to the Vaal System by approximately 465 million m3 to make a total of 1 255 million m3 per annum.