Polihali Dam and Transfer Tunnel Contracts Awarded In Lesotho

The Lesotho Highlands Development Authority announced the contract awards in early November.

By Chriselle Moraes on
30th November 2022

The Lesotho Highlands Development Authority (LHDA) has announced the award of contracts for construction of the Polihali Dam and the Polihali Transfer Tunnel. 

These are two of the biggest Phase 2 contracts awarded by LHDA to date and are part of the Lesotho Highlands Water Project (LHWP). The award of the dam and transfer tunnel contracts marks the beginning of the final stage of the water transfer infrastructure construction for the LHWP. 

The Polihali Dam is a concrete-faced rockfill dam, like the majestic Mohale Dam which was constructed in Phase 1 of the LHWP.  It will create a reservoir on the Senqu and Khubelu rivers with a surface area of 5 053 hectares. The infrastructure also includes a spillway, a compensation outlet structure and a mini-hydropower station.

The Polihali Transfer Tunnel will transfer water by gravity from the Polihali reservoir to the Katse reservoir, the centrepiece of the LHWP. From Katse, water is transferred via the delivery tunnel to the Muela Hydropower Station constructed in Phase 1, and then on to the Ash River outfall outside Clarence in the Free State on its way to Gauteng.

The Polihali Transfer Tunnel works also includes the intake works and gate shaft at the Polihali reservoir; outlet works and gate shaft at the existing Katse reservoir, with underwater connection to the lake; access adits to the waterway and associated construction infrastructure.

The transfer tunnel will be approximately 38 kilometres long with a nominal bore of five metres. Both tunnel boring and drill and blast methods will be used to excavate the tunnel.

The contract amount for the Polihali Dam is M7.68 billion (Maloti), approximately US$452 million.

The contract for the Polihali Dam was awarded to the SUN Joint Venture, comprising Sinohydro Bureau 8 (China); Sinohydro Bureau 14 (China); Unik Civil Engineering  (South Africa) and Nthane Brothers (Lesotho) as the main joint venture partners. Subcontractors include Melki Civils and Plant Hire (South Africa); MECSA Construction (South Africa); SIGMA Construction (Lesotho) and Kunming Engineering (China).

Construction of the dam will be supervised by the Matla a Metsi Joint Venture, comprising GIBB (South Africa); MPAMOT Africa (South Africa); Tractebel Engineering SA/Coyne et Bellier (France) and LYMA Consulting Engineers (Lesotho).

The contract amount for the Polihali Transfer Tunnel is M9.2 billion (Maloti), approximately US$542 million.

The contract for the Polihali Transfer Tunnel was awarded to the Kopana Ke Matla Joint Venture, comprising Yellow River Company (China), Sinohydro Bureau 3 (China), and Unik Civil Engineering (South Africa) as the main joint venture partners. Subcontractors include Nthane Brothers of Lesotho, Esor Construction and Mecsa Construction of South Africa.

Construction of the tunnel will be supervised by Metsi a Senqu-Khubelu Consultants (MSKC) joint venture, comprising Lesotho-based FM Associates and South African firms Zutari South Africa, Hatch Africa, Knight Piesold, and SMEC South Africa.

Construction works are expected to begin in November and December for the dam and tunnel respectively. Commissioning of the facilities is expected to take place in 2028.

Phase 2 of the Lesotho Highlands Water Project builds on the successful completion of Phase 1 in 2003. Phase 2 adds 2,325 million cubic metres in storage capacity to the LHWP and will increase the current annual supply rate capacity from 780 million cubic metres to 1,270 million cubic metres, contributing towards meeting South Africa’s increasing water needs. The additional flow of water from Polihali will simultaneously increase power generation within Lesotho towards meeting Lesotho’s domestic needs and reducing the country’s dependence on electricity imports.

“This is an exciting moment for the Project and the LHDA. With our experience in successfully delivering large and complex infrastructure projects, we are confident that we will deliver quality engineering showpieces even as we carefully manage impacts on people and the environment,” confirmed Tente Tente, Chief Executive, LHDA. “Both joint ventures include Lesotho, South African, and international companies in keeping with Article 10 of the Phase II Agreement.”

The procurement process for the design and construction supervision of the Oxbow Hydropower Scheme, a critical component of Phase 2, has also begun. March 2023 is the deadline for submitting bids for engineering, environmental and social consultants. 

The project will help in direct and indirect job creation during the development phase. The construction sector will benefit from the project during 2022-23. Most economic benefits will be acquired only by 2028 once the project becomes operational. After LHWP Phase 2 starts generating electricity and exporting water, Lesotho is expected to see an increase in revenue generation.

Top Photo: Katse dam wall in Lesotho (Tjkphotography | Dreamstime)

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