The second phase of the Lesotho Highlands Water Project (LHWP) continues to advance steadily, maintaining its momentum after overcoming a range of challenges.

The LHWP Phase II experienced initial delays owing to leadership transitions in both South Africa and Lesotho, complex decision-making processes, procurement adjustments, lengthy regulatory approvals, labour negotiations and the global disruption caused by the Covid-19 pandemic, among others.

Since gaining momentum in 2023, a year described as a milestone for the project, progress – a testament to resilience, innovation and collaboration – remains on track, bringing the ambitions of increased water supply to South Africa and energy security for Lesotho one step closer to realisation.

“From overcoming delays and logistical challenges to fostering community engagement and environmental stewardship, the project reflects a commitment to balancing technical excellence with social responsibility,” the Lesotho Highlands Development Authority (LHDA) said in a statement sent to Engineering News & Mining Weekly.

Navigating these complexities with strategic foresight – through proactive planning, stakeholder engagement and adaptive execution – the LHDA likens the progress to an intricate symphony of “maths and music” that serves as a model for large-scale infrastructure projects worldwide.

“Executing large-scale infrastructure projects combines maths and music: the maths of delivering multiple highly technical engineering components within a specific timeframe and budget, and the music of the softer skills of diplomacy, communication, social responsibility, environmental and community safeguarding, while at the same time considering the interests and expectations of multiple, diverse stakeholders. The LHWP is no exception.”

This critical project includes the Polihali dam, where the upstream cofferdam was completed to design height in early 2024, with work completed by the end of the year to elevate it further to mitigate flood risk.

According to the LHDA, excavation of the main dam abutments, plinth areas, intake tower, saddle dam and spillway approach is advancing steadily, alongside rockfill placement on the trial and main dam embankments.

In the early part of this year, the project’s activities are focused on the main dam rockfill placement, construction of the main dam plinth and excavation of the intake tower.

“The first major 2025 milestones expected are rockfill to EL 1977, construction of the main dam plinth to EL 1980 and excavation of the intake tower to reach the bottom EL 1980 by mid-2025, according to the current construction programme.”

Meanwhile, major milestones in the Polihali transfer tunnel construction included the August 2024 breakthrough of the upper intake tunnel into the lower intake tunnel after seven months of tunnelling.

By the end of 2024, significant progress had been made on the construction of the Polihali access adit and the Polihali gate shaft.

Construction of the Polihali connecting tunnel and the Katse access adit are under way.

In January, tunnel boring machine (TBM) excavations started from the Katse end of the tunnel, and had covered a distance of 100 m by mid-February.

This followed the arrival, in September last year, of 126 pieces of the first of two double-shielded TBMs designed to excavate the 38 km Polihali transfer tunnel, in Lesotho.

After successful factory acceptance tests in China, the TBM, named Khoiti ea ‘Ngoaha Kholo2 (the rat mole of 200 years), embarked on a month-long voyage to Durban, which saw a convoy of 90 heavy-duty trucks transporting the TBM parts by road through the South African provinces of KwaZulu-Natal and the Free State and through the Calendonspoort border post into Lesotho.

The second TBM is expected to arrive at the Polihali site in July, where it will be reassembled and named, as is customary, ahead of the start of excavation from the Polihali end of the tunnel.

Excavation of the tunnel is expected to take two-and-a-half to three years.

Further, the LHDA awarded two contracts for the engineering design and construction supervision and environmental and social impact assessment (ESIA) for the Oxbow hydropower scheme in late 2024.

Work on the R842-million design and construction supervision contract started in early January and is expected to take 92 months to complete.

The successful bidder is a joint venture (JV) comprising Lesotho, South African and international firms, including France’s Artelia, Australia’s SMEC International, South Africa’s SMEC and Lesotho’s GWC Consulting Engineers.

The R12.5-million ESIA contract, which started in January and is expected to be completed within a year, was awarded to the ELC, Greenway and Green Gold JV, which comprises Italy’s ELC Electroconsult, Lesotho-based Greenway Consultancy and South Africa-based Green Gold Group.

Meanwhile, roads and bridges are critical components of the Phase II infrastructure.

The three main access roads, the Polihali western access road, the Polihali north-east access road and the Northern access road, which were constructed as part of the advance infrastructure and have been in use for several months, are now nearing final completion.

The access roads facilitate the transport of heavy equipment, including the TBMs, and ensure efficient connectivity to Maseru through the A1 road.

In addition, the Senqu bridge, the largest of three bridges spanning the Polihali reservoir, is now more than 70% complete.

“All 15 piers and pier heads have been completed and, by the end of 2024, about 25% of the deck, which is being constructed incrementally from both abutments, had been completed,” the LHDA explains.

The second deck of the Senqu bridge was launched in mid-February to reach Pier 14 – the first time the deck spanned 50 m.

Hydraulic jacks pulled the deck forward 30 cm at a time, extending the deck across the span by about three metres an hour.

“A delicate operation, every millimetre of movement of the deck, cables and the piers was carefully monitored by tilt meters, strain gauges, lasers and theodolites and the watchful team of engineers, technicians and surveyors,” the authority points out.

“Stacked ultra-smooth Teflon pads at all of the load-bearing points ensured the deck slid smoothly, despite its massive weight.”

The 880-m-long, 110-m-high Senqu bridge is the first extradosed bridge in Lesotho.

It is expected to be open to traffic in the first quarter of 2026, according to the current construction programme.

The Mabunyangeng and Khubelu bridges have also progressed steadily.

Construction of the eight piers of the Khubelu bridge and the piling for the Mabuyaneng bridge piers was completed at the end of 2024, and the combined progress at mid-January was 47.38%.

A feeder roads and bridges programme, comprising 94.2 km of feeder roads, one-third of which are paved, and are a mix of greenfield and brownfield roads, four pedestrian bridges between 250 m and 750 m long, and six vehicle bridges with lengths between 72 m and 422 m, complements the access roads and the major bridges.

“Its purpose is to mitigate the impact of the Polihali reservoir on local communities, restoring accessibility to affected communities, restoring or improving access to community facilities such as schools, markets and clinics as well as integrating existing and resettled villages into the national road network.”

According to the LHDA, the layout and location of these new or improved roads and bridges were determined through an extensive master plan study to identify the current movement patterns around and across the river valleys to be inundated.

The new bridges will provide strategic crossing points across the future reservoir linking to the feeder roads so as to retain and improve the identified existing or required vehicle and pedestrian mobility routes.

The LHDA awarded the design and construction supervision contract for the feeder roads and bridges programme to the Khubelu JV in January.

The JV, under Lesotho’s Pemahn Consulting as the lead partner, includes South African partners KBK Engineers and Bosch Projects, as well as subconsultants Lesotho-based Nala Environmental Services and South Africa-based Strutie Group.

Design work has already started, with construction work set to begin towards the end of 2026.

Progress has also been made on project housing, constructed as part of the Phase II advance infrastructure by Lesotho and South African construction firms.

The Polihali Operations Centre, which houses the LHDA’s Polihali office and consultant offices, was completed towards the start of 2024.

The refurbished Katse Lodge and Katse Village offer enhanced visitor experiences, while the Polihali Commercial Centre will soon host retail businesses, benefiting local communities.

Meanwhile, one of the recent project management achievements is the formation of a project-wide Bargaining Forum, which was launched in early March and its constitution signed.

The forum includes the LHDA, all project contractors and trade unions in Lesotho.

Its purpose is to address labour-related challenges that can lead to work stoppages, and to ensure better engagement between workers and their employers, and understanding of the contracts and projects.