WATER INFRASTRUC TURE
The Polihali diversion tunnels outlet
Lesotho Highlands Water Project Phase II: Overview and Update KEY COMPONENTS OF THE PROJECT • Polihali Dam - This will be a concrete-faced rockfill dam. - The embankment will be 163.5 m high and 470 m wide (at its base). The crest is 921 m long and 9 m in width. - Over 13 million cubic metres of rock, which will be quarried locally within the dam basin and will be compacted to form the embankment. - The dam will create a reservoir on the Senqu and Khubelu rivers with a surface area of 5 053 ha and a full supply storage capacity of 2 325 million cubic metres. - Polihali Dam infrastructure includes a spillway, a compensation outlet structure and a small hydropower station. - The saddle dam will be 45 m high and will have a crest length of 603 m and a crest width of 6.5 m. Its function is to raise a low point on the reservoir margin to prevent water from bypassing the Polihali Dam. - The current supply rate of water from Lesotho to Gauteng will increase at the rate of 780 million cubic metres per annum incrementally to more than 1 270 million metres per annum, as a result of the water volume increase brought about by the construction of the Polihali Dam. • Polihali Transfer Tunnel - The Polihali Dam will be built downstream of the confluence of the Khubelu and Senqu rivers in the Mokhotlong district in the Eastern highlands of Lesotho. - A 38.2 km long and 5.2 m diameter water
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transfer tunnel will link the Polihali reservoir to the Katse reservoir. - Just as the water from the Mohale reservoir flows through the interconnecting Mohale Transfer Tunnel to the reservoir at Katse, so will water from the Polihali reservoir flow through the Polihali Transfer Tunnel on its way to Katse, increasing the supply of water to the Katse reservoir and the amount of water available for hydropower generation. • Hydropower - Feasibility studies are completed. It is decided that conventional hydropower is the best option. - Three potential sites have been identified: two on the Senqu River and a third site at Oxbow on the Malibamats’o River. - The plan is • 2021: begin the design of the preferred option • 2024: begin construction • 2027: commission at same time as water transfer component. • Advance infrastructure - T his will largely be completed before the construction of the dam and tunnel begins: • roads • bridges • housing • offices • workshops • bulk power • telecommunications networks – support project implementation and benefit Lesotho in the long term.
EMPLOYMENT • 1 123 people from villages within a 5 km radius of the advance infrastructure areas have been placed with different contractors for unskilled positions. • 1 764 skilled personnel are engaged on Phase II construction contracts, of whom over 80% are Lesotho nationals while the remainder are from South Africa and other countries. • At the peak of construction, Phase II is expected to create between 2 000 and 3 000 unskilled job opportunities for Lesotho nationals. Polihali Western Access Road
