Phase II of Lesotho Highlands Water Project Roars to Life

Writes Manyathela Kheleli

The commencement of Phase II of the Lesotho Highlands Water Project (LHWP), does not only bring to fruition, the aspiration of watering the economic aspirations of both Lesotho and South Africa, but also continues to cement the bilateral bond between the two neighbours. Lesotho continues to project itself as a hub for sustainable freshwater resources in the region. This has rendered the country to become a strategic ally in the economy and geopolitics of the SADC region, as Lesotho’s water wealth has the potential to bring change and influence the economy of the SADC region.

On 23 May 2023, King Letsie III and the President of the Republic of South Africa, Cyril Ramaphosa officiated the sod turning of the estimated M42 billion Lesotho Highlands Water Project Phase II at Polihali in Tlokoeng, in the Mokhotlong district. The project is the second phase in the implementation of a treaty that was signed by the two countries in 1986 for the construction of infrastructure to provide water to the industrial hub of South Africa, Gauteng, whilst simultaneously generating hydroelectricity for the Mountain Kingdom. President Ramaphosa says the project is a beacon of hope, a symbol of progress, a symbol of international cooperation and a testament to the strength of bilateral relations between the Kingdom of Lesotho and the Republic of South Africa. 

When complete, Phase II will deliver the third dam of the multibillion project at the confluence of Khubelu and Senqu rivers, which will pump an additional 400 million cubic meters of water to the Vaal dam. Phase I made up of Katse and Mohale Dams commissioned in 2004 currently delivers about 780 cubic metres of water per annum. This export of water, aptly referred to as Lesotho’s ‘white gold’, earned the national fiscus royalties amounting to M1.33 billion as at the end of 2022.

With tenders for the main works valued at approximately M20 billion, the construction at Polihali marks yet another milestone that will change the fortunes of Lesotho. Currently reeling from massive unemployment and slow economic growth, Phase II presents an opportunity for Lesotho to get out of the woods and to improve its infrastructure.  In the short term, the construction will spur economic growth and create about 6 000 jobs for the next five years, while in the long run, the country will benefit from ancillary roads and other developments created by the project. Lesotho will also earn more royalties and become self-sufficient in power generation.

The construction of Polihali Dam, which is the ultimate objective of LHWA Phase II, was preceded by the building of advance infrastructure that included the construction of access roads, bridges, power lines, two diversion tunnels and accommodation facilities for the contractors. The historic sod-turning ceremony at the damsite on 23 May 2023 marked the beginning of the multi-billion project.

The construction at Polihali entails the building of the dam wall, a tunnel that connects Polihali to the main Katse reservoir and the construction of bridges, the main one being the Senqu bridge. Billions of maloti worth of tenders have been awarded to international, regional and local sub-contractors for the works that will see the creation of about 6 000 jobs in the country in the next five years. During this period, the construction is expected to provide an economic stimulus that is projected to contribute about 5% of annual year on year growth to the country’s GDP,

Similar to the Mohale Dam, the Polihali Dam wall will be a 166-meter Concrete Face Rockfill Dam (CFRD). The dam will create a reservoir on the Senqu and Khubelu rivers with a surface area of 5 053 hectares and a full supply storage capacity of 2 325 million cubic meters.  The dam embankment will be constructed in compacted layers from free draining rockfill, sourced locally in the Lesotho highlands, very close to the dam. The main dam embankment will contain 15 million cubic meters of rockfill together with the 43m Saddle Dam (also a Concrete Face Rockfill Dam) which will be made up of a total of 1.25 million cubic meters of rockfill. Using rockfill has a further advantage in that, placement can continue during periods of heavy rainfall, which is a frequent occurrence in Lesotho. Polihali Dam is designed to be constructed in stages to allow overlapping of the major activities on the critical programme path. This method also shortens the construction period and has a further advantage in that impoundment can be initiated during the construction period. The dam will also include a spillway, a compensation outlet structure and a mini-hydropower station.

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

At the time of the award, the contract was valued at approximately M7.68 billion. The construction of the dam wall is projected to be completed in 2029. Depending on the climatic conditions, the Polihali reservoir could be filled to capacity between two to seven years after the start of the impoundment of water. However, based on the experience of Katse and Mohale dams that were filled in record time, it is expected that Polihali will also reach its storage capacity ahead of time.

The second key deliverable in the implementation of Phase II is the Polihali Transfer Tunnel which is intended to transfer water by gravity from the Polihali reservoir to the main Katse reservoir, the centrepiece of the LHWP. From Katse, water is further transferred through the delivery tunnel to the ‘Muela Hydropower Station constructed during Phase I, and then on to the Ash River outfall outside Clarence in the Free State on its way to Gauteng. The transfer tunnel from Polihali to Katse is five meters in diameter and will cover 38 kilometers. Both tunnel boring, as well as drill and blast methods will be used to excavate the tunnel.

The Polihali Transfer Tunnel construction 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 tunnel boring machine to be used is a double-shield gripper TBM, with precast concrete segmental lining, erected and grouted at the rear of the TBM.  A double-shield machine is able to simultaneously excavate the rock and erect the segments, while the machine is fully protected by the shield. With shield and segments, the tunnellers are never exposed to unsupported ground, and in effect, never see the rock, except for the spoil emerging from the cutter head.

With a total contract value of approximately M9.2 billion, the tender for the construction of the tunnel has been awarded to the Kopano Ke Matla joint venture made up of Yellow River Company (China); Sinohydro Bureau 3 (China) and Unik Civil Engineering (South Africa) who are the main joint venture partners. Subcontractors include Nthane Brothers of Lesotho, Esor Construction and Mecsa Construction of South Africa.

The tunnel is expected to be completed in 2028, almost a year ahead of the completion of the dam wall.The project also includes the construction of three major bridges under Phase II. The first of the three major bridges is the Senqu Bridge. Almost a kilometer long (825m) and at a height of 90m, the Senqu Bridge will be the first extradosed bridge in Lesotho and is larger than the Mphorosane Bridge on the Malibamatšo River which spans the Katse Dam and was constructed under Phase I of the Project. Mphorosane is only about 465 meters with a height of 86 meters. When complete, Senqu bridge will set a new record as the longest and tallest bridge in Lesotho. It is also the largest of the three bridges that will be constructed under Phase II to span the Polihali reservoir. The bridge design has taken into consideration the Mokhotlong highlands’ long, cold and harsh winter conditions.

Due to the deep valley and the terrain of the area, the deck will be constructed incrementally from both abutments. This construction method will minimise disturbance to the surrounding work area and increase workers’ safety.  An in-situ segment midspan of the centre span will connect the two parts to form a continuous deck. The pier shape has been preferred as ideal to be constructed with sliding formwork. The bridge was designed by Zutari, formerly Aurecon Lesotho, who will also oversee the works. The two other bridges to be constructed are Mabunyaneng and Khubelu bridges.

The tender for the construction of this major bridge was awarded to the WRES Senqu Bridge Joint Venture at the approximate value of M2 billion.  The WRES Joint Venture includes South African, Lesotho and international companies as per the requirements of the Phase II Agreement.  The primary partners are:  Webuild S.p.A. (Italy); Raubex Construction (Pty) Ltd (South Africa); Enza Construction (Pty) Ltd (South Africa) and Sigma Construction (Pty) Ltd (Lesotho). Sub-contractors include:  EXR Construction (Pty) Ltd (South Africa; Gleitbau-Geselschaft (Austria); Post Tensioning and Structural Solutions (Pty) Ltd (South Africa) and Freyssinet International et Cie (France).

The procurement of all works was guided by Article 10 of the Phase II agreement between the governments of Lesotho and South Africa. In particular, Article 10 (b) states that preference for contractors and consultants shall be given in the order of Lesotho, South Africa, SADC Member States, and international in the awarding of the contracts provided that such suppliers meet the requirement in terms of cost and quality in the manner that advocates for competitiveness and transparency. At close analysis, the magnitude of the project has dictated that major contractors will be drawn from international players, predominantly from China, Austria and France. South African companies have also featured considerably and Lesotho Companies have also been a party to the joint ventures. Nthane Brothers is one such beneficiary, the company is part of the main contractors in the SUN joint venture awarded the tender for the construction of the dam wall. As a rough estimate, in the tender for the tunnel contract, the minimum participation for Lesotho contractors is 14.3%, which in monetary terms is over M1.3 billion according to the LHDA.

With regard to employment, all unskilled labour will be sourced from the project area and other areas within Lesotho. Recruitment is managed off-site by an independent labour recruitment consultant, in collaboration with local community structures and oversight by the Department of labour. Phase II construction is expected to create approximately 3 000 unskilled jobs. All unskilled jobs are reserved for Lesotho nationals. Data on the number of jobs that will be created during the construction of the Senqu Bridge, the Polihali Dam, and the Polihali Transfer Tunnel specifically is estimated at around 6 000 jobs.

The impact of Phase II of the LHDA on the economy of Lesotho cannot be overemphasised. Indicative estimates that are yet to be ratified by the Central Bank report project that Phase II contributes to about 5% of GDP and 10% of annual government revenue year on year. Much of this trend has already been evident in the construction works of the advance infrastructure, and indications are that the trend is going to surge with major works underway. The economic spillovers from the dam infrastructure construction will also affect other industries such as transport and fuel, tourism and the retail sector. At the household level, the quality of life for Basotho employed in the project will make a huge difference in transforming lives.

During the conceptualisation of the Polihali Project, the LHDA also factored the facilitation of other downstream economies for the benefit of Basotho. The Authority has recently approved its new 10-year strategy which, unlike previous times, explicitly spells out the maximisation of commercial opportunities and development of business enterprise as a key strategic goal. In that goal, is the intent to explore tourism and fisheries as a key commercial opportunity and business area that the project intends to develop for the benefit of Basotho in the project area and beyond.

The amount of water delivered each year is agreed upon by both governments and is managed in terms of an approved water schedule. The current supply rate is 780 million cubic meters per annum. The Polihali Dam will add another 2 322 million cubic meters in terms of storage capacity enabling an incremental increase in water transfer volume to 1 270 million cubic meters per annum. Water delivery from Polihali is expected to start as soon as the commissioning is done in 2028.

On the generation of hydropower for consumption in Lesotho, the government confirmed the Oxbow Hydropower Scheme on the Malibamatšo River in November 2021. Procurement for the design and construction supervision of the Oxbow Hydropower Scheme commenced in late October 2022 and is underway as is the procurement of consultants for the environmental assessment (ESIA) and the resettlement action planning (RAP) associated with the Oxbow Scheme. According to the current master programme, construction of the Oxbow scheme is expected to commence in 2026. The scope of the Oxbow Hydropower dam includes a 100-metre high dam, two tunnels and a high-pressure steel pipeline as well as a power station that will produce an installed capacity of 80 MW of power from four turbines to ensure the country’s self-reliance with electricity. The capacity of Oxbow will add a total of about 40% to the grid. There will also be an additional 40% to the electricity generation capacity of ‘Muela as a result of the increased flow of water from Polihali. Power generation is expected to commence in early 2030. The Oxbow Hydropower Scheme will significantly increase the security of power for Lesotho and possibly render the country self-sufficient in power when added to the output of the solar power generation project at Ha-Ramarothole.