The tender for the Polihali dam construction will follow shortly. The transfer tunnel will be 38 km long with a 5 m nominal bore. It will transfer water by gravity from Polihali to the Katse reservoir. Tunnel boring and drill and blast methods will be used to excavate the tunnel.
Polihali dam will create a reservoir on the Senqu and Khubelu rivers with an estimated surface area of 5053 ha and a full supply storage capacity of 2325 x 106m3. The flow from the Polihali reservoir through the transfer tunnel will increase the volume of water in the Katse dam. The current water transfer volumes of 780 x 106m3/year to the Gauteng region of South Africa; this will incrementally increase to 1270 x 106m3/year, and will simultaneously increase the electricity generation at the ‘Muela hydropower plant in Lesotho, a further step in the process of securing an independent power supply to meet the country’s domestic needs.
According to Tente Tente, CE of the LHDA: “Our objective is to attract firms with experience in the construction of major underground works under complex geological and geotechnical conditions, diverse environmental conditions, in remote areas and at high altitude. Equally important is to attract companies that have impeccable records in delivering projects of this magnitude within budget and the set timeframes.”
The Metsi a Senqu-Khubelu Consultants (MSKC) Joint Venture was awarded the contract for the design and construction supervision of the Polihali Transfer Tunnel and its secondary structures.
MSKC comprises Lesotho-based FM Associates (Pty) Ltd, and South African firms Zutari (Pty) Ltd, Hatch Africa (Pry) Ltd, Knight Piesold (Pty) Ltd and SMEC South Africa (Pty) Ltd.
The tender for the construction procurement of the transfer tunnel was launched on ten advance infrastructure contracts and is progressing steadily, with some contracts expected to be completed later this year, including the Polihali diversion tunnels.
Cumulative excavation progress to date in both tunnels is in the order of 1243 m of a total of 1810 m. Construction of the 33 kV line, which will provide temporary power supply to the Polihali village, was completed in 2020. Work on the 132 kV line has advanced with construction of access roads and 91 tower foundations and the erection of 84 towers of a total of 93. The Polihali and Katse civil works; access roads, pipe laying for potable water and sewerage lines have been completed, and construction on the Phase II main access roads is progressing well.
According to the current master programme, water delivery is scheduled for 2027. Construction of the dam and transfer tunnel being on schedule is critical to meet the water delivery deadline of the project.
Phase II of the Lesotho Highlands Water Project builds on the successful completion of Phase I in 2003, the main element of which was the 185 m-high Katse arch dam.
Interested construction firms for the transfer tunnel tender have until 30 August 2021, to submit bids. Specific information on the requirements and conditions of the tender is available on the LHDA website (see below)
For additional information, contact: The Public Relations Manager LHDA PO Box 7332, Maseru 100 Lesotho Tel: +266 22246000 Email: email@example.com or firstname.lastname@example.org Website:www.lhda.org.ls