Progress is being made on the maintenance and repair of the Lesotho Highlands water tunnel, which was shut down more than a month ago to undertake the critical work that will ensure the infrastructure’s longevity.

Since the total shutdown on October 1 for six months, the tunnel, which transfers a contracted 780-million cubic metres of water a year into South Africa, has been emptied of water and general inspections have been conducted – essential activities required before repair works started on November 1.

The Trans Caledon Tunnel Authority (TCTA), responsible for implementing the maintenance in conjunction with the Lesotho Highlands Development Agency (LHDA), appointed a contractor to execute maintenance operations on the 38 km of the Lesotho Highlands tunnel in South Africa.

The LHDA is focusing on the transfer tunnels at the Muela hydropower station in Lesotho.

Both implementing agents will conduct the maintenance work concurrently until completion on March 31, 2025.

Maintenance work on the tunnel takes place every five years to ensure longevity, reliability and integrity of the tunnel for continuous transfer of water from the highlands of Lesotho into South Africa.

TCTA CEO Percy Sechemane says that this maintenance period is the longest since the tunnel came into operation in 1998. As the infrastructure was relatively new, it did not need extensive maintenance until now.

The tunnel is still in good condition and the TCTA does not foresee any challenges in meeting the targeted completion date, he told Engineering News & Mining Weekly during a media tour of the dewatered tunnel in the Ash River Outfall, in Clarens, Free State, earlier this month.

TCTA project management and implementation executive manager Johannes Mavuso explains that the repair work on the tunnel started on November 1 and is scheduled to end on February 28, 2025, to enable the release of water from Lesotho to reach South Africa by March 31.

The work under way includes various technical, civil, mechanical, electrical engineering work, as well as sand sandblasting, recoating of the tunnel's steel lining and removing corrosion that has built up over many years.

Repair work will also be done on the precast concrete segment lining within the tunnel.

During the media tour, Water and Sanitation Deputy Ministers David Mahlobo and Sello Seitlholo expressed satisfaction with the progress made so far.

“The maintenance will enable the parties to sweat the asset for the next 20 years and guarantee assurance of supply. It is a necessary inconvenience, a small pain over a short period,” said Mahlobo, commending the progress made regarding the maintenance work.

Water from the Katse dam in Lesotho flows through the tunnel into the Ash and Liebenbergsvlei rivers in the Free State, then into the Wilge river, eventually spilling into the Vaal dam. The Ash and Liebenbergsvlei rivers supply water to the local municipalities of Dihlabeng, Nketoana and Mafube in the Free State, as well as to the agricultural irrigators in the area.

“I must add that we are proud of the TCTA, which has employed South African expertise in the maintenance operations of this nature, both engineering and technical in nature. We are confident that the operations will take place as planned until the tunnel is reopened again next year in March,” he adds.

While there are risks that could delay the project – such as rain, poor performance by contractors and local labour expectations – Mavuso said work in the tunnel is being carried out in a controlled environment, with only work on the Ash river expected to be affected by rain. Several control measures are in place, including a war room to monitor progress, daily progress meetings with contractors, weekly progress updates against baseline schedules, monitoring of deviations from schedules, implementing recovery plans if required, monthly interface meetings between the TCTA and the LHDA, and on-site quality assurance.

The war room, which includes the Free State Department of Cooperative Governance and Traditional Affairs, the TCTA and municipal managers from the Mafube, Nketoana, Setsoto, Dihlabeng and Mantsopa local municipalities, tracks progress on the tunnel maintenance work.

The war room also constantly monitors the progress made by municipalities on dam levels, leak repairs, construction of water infrastructure and drilling of boreholes to ensure sustainable water supply to communities, particularly those affected by the tunnel shutdown.

“There was proper planning before the tunnel shutdown and the assessment was made for the affected municipalities in the Free State as well as in Gauteng province,” Mahlobo comments.

About 700-million cubic metres of water had been transferred in anticipation of the closure, with 2024’s balance of 80-million cubic metres of water to be transferred once maintenance has been completed.

This enabled South Africa to receive most of its yearly water deliveries, ensuring that both the water supply and the royalties revenue that Lesotho receives from those deliveries are minimally disrupted.

Mahlobo assured that there will be enough water supply until the completion of the maintenance operations – with a three-month buffer beyond the initial six months – as the Sterkfontein dam will be on standby to release water into the Vaal dam should it drop to 18%.

“There are contingency measures in place to ensure that the Vaal dam, which mainly supplies Gauteng, will be topped up from other storage dams within the Integrated Vaal River System (IVRS), if it reaches critically low levels.”

The DWS-managed IVRS, which comprises 14 interconnected dams through a system of rivers, canals, tunnels, pipelines and pump stations, has enough water for the duration of the maintenance period, and, if needed, water can be transferred from one part of the system to another.

The IVRS includes the Vaal, Sterkfontein, Grootdraai and Bloemhof dams, besides others, which are augmented by the Katse and Mohale dams in Lesotho.

Seitlholo says that, although the municipalities are taking a strain, the Department of Water and Sanitation (DWS) will continue to provide support to ensure sustainable water supply to communities. He has, however, encouraged municipalities to be responsive to issues of water supply and also address the problem of water loses owing to illegal connections and aging infrastructure.

“Issues of water supply challenges in municipalities should receive urgent attention and there should be continuous conversations about them. Loss of water to the ground before it even reaches our communities needs to be tackled in most municipalities because it results in unsustainable service delivery, particularly that we are a water-scarce country.”

“If we do not fix local government, there will be more problems that will continue to persist in the country,” he warns.

Free State acting Premier Jabu Mbalula acknowledges the support the that the province has been given by the DWS in matters of water security within the province.

“Today, we were exposed to the beauty of engineering and through our intergovernmental relations we are certain that Free State province will not suffer in terms of sustainable water supply to our communities.”

“As Free State, we reiterate the call for our communities to continue to use water sparingly, as we all know that water is a scarce resource. We are happy with the progress of the maintenance work which had minimal effect on water supply to our residents in the Free State,” he says.