Infrastructure
$1.6B Water and Dam Project Breaks Ground in South Africa
Second phase of massive water-transfer effort gets underway
The Katse Dam in Lesotho, part of the completed first phase of the Lesotho Highlands Water Project. The new Polihali Dam will deliver water to the Katse Reservoir.
Photo Courtesy Lesotho Highlands Development Authority
The second phase of Africa’s largest water transfer scheme—the Lesotho Highlands Water Project—has broken ground paving way for construction of a $856-million dam and water transfer tunnel. LHWP is a binational undertaking by South Africa and Lesotho.
The project is a network of dams and water tunnels in Lesotho’s Senquanyane river basin that delivers water to South Africa’s Vaal River System. It is biggest system in the nation, with 14 dams in four provinces.
South African President Cyril Ramaphosa led Lesotho’s King Letsie III and Lesotho’s Prime Minister Samuel Matekane on May 23 in launching the phase that involves construction of Polihali dam and a 38-km water transfer tunnel expected to be commissioned in 2028.
Completion of this phase, estimated to cost $1.7 billion, will increase the volume of water transferred from Lesotho to South Africa from the current 780 million cu meters to 1260 million cu m.
The Polihali dam is a 163.5-m-high concrete-faced rockfill dam and has an associated 50-m-high saddle dam, with a water storage capacity of 2,200 million cu m, covering 5,053 hectares, downstream of the confluence of Khubelu and Senqu (Orange) River.
The Polihali water tunnel will deliver water by gravity from the new Polihali Dam to Katse Reservoir—completed in phase one of LHWP in 2003—before the water is transferred via the delivery tunnel to the 72-MW Muela hydropower station in Lesotho, also constructed in the first phase, and subsequently to South Africa.
The water tunnel will be excavated by a tunnel boring machine, though significant lengths of the work will also involve drill and blast tunneling, according to Australian-based construction engineering firm SMEC Holdings, headquartered in Melbourne.
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The tunnel design includes two gate shafts for future management of its operations. Each gate shaft has stoplogs, gates, dewatering pumps and filling valves, according to SMEC. “A notable technical feature of the project is the Katse lake tap, where the tunnel is designed to be excavated into a dam basin below water level,” SMEC says.
SMEC had in 2021 completed the excavation of two 1,870-m, 7-m-dia and 9-m-dia water diversion tunnels to create dry areas for the construction of the Polihali dam.
Contracts for both the Polihali dam and water transfer tunnel were awarded by Lesotho Highlands Development Authority (LHDA) in the fourth quarter of 2022. The Authority is the implementing agency for LHWP while South Africa’s Trans-Caledon Tunnel Authority provides the financing.
The SUN Joint Venture, made up of Chinese, South African and Lesotho-based companies was awarded the approximately $390-million Polihali dam contract. Kopana Ke Matla JV comprising French, South Africa and Lesotho contractors was awarded the $467-million water transfer tunnel contract.
The project management contract was awarded to Metsi a Senqu-Khubelu Consultants JV, comprised of Lesotho-based FM Associates and South African firms Zutari South Africa, Hatch Africa, Knight Piesold and SMEC South Africa, the main joint venture partners.
“We are confident that we will deliver quality engineering showpieces even as we carefully manage impacts on people and the environment,” says Mr Tente Tente, chief executive, LHDA.
The LHWP phase two also includes construction of the 80-MW Oxbow hydropower station. There also are plans to divert the course of Malibamatso River, the main branch of Senqu (Orange) River, through a tunnel before construction can begin.
The Trans-Caledon Tunnel Authority said in 2021 it had concluded funding agreements for the project to the tune of $782 million, working with financial institutions such as Absa, the African Development Bank, Development Bank of Southern Africa, Investec, the Industrial Development Corporation, Nedbank, New Development Bank, Rand Merchant Bank and Standard Bank.
At least 6,000 temporary jobs will be created for the construction phase with another 5,500 direct and indirect new jobs expected during operation of the water transfer infrastructure.
