Name and Location
Lesotho Highlands Water Project (LHWP) – Phase II, Lesotho to South Africa.

Client
The Lesotho Highlands Development Authority (LHDA) and the Trans-Caledon Tunnel Authority (TCTA) are the implementing authorities.

The Lesotho Highlands Water Commission has an oversight function, advises the two governments and monitors the activities of the LHDA and TCTA.

Project Description
Phase I of the LHWP was officially completed in 2004.

Phase II of the LHWP will be implemented in terms of two distinct components: a water delivery system to augment the delivery of water to South Africa and a hydropower generation system.

Polihali dam
The Polihali dam will be built downstream of the confluence of the Senqu and Khubelu rivers and will be a 163.5-m-high concrete-faced rockfill embankment dam wall.  The crest length will be 915 m, with a full supply level of 2 075 m above sea level.  A 49.5-m-high saddle dam and a side-channel spillway will also be built.

Polihali to Katse tunnel
The 38.2-km-long, 5-m-diameter Polihali to Katse dam tunnel will be constructed to transfer water from the Polihali reservoir to the Katse dam. The tunnel is sized to convey a peak power generation flow of 35 m3/s. Water will be abstracted from the Polihali reservoir through two separate concrete bell-mouth intakes on the western side of the Polihali reservoir, in the Khubelu river, 3 km upstream of the confluence with the Senqu river. Water will be transferred through the lower and upper intake tunnels to the intake gate shaft. Both tunnels will be constructed using drill-and-blast methods and will be fully concrete-lined. Hydraulic control will be effected by the valves in the intake structures.  The Polihali intake gate shaft will be used only for maintenance and water-quality control functions.

Advance infrastructure
Where possible, the existing infrastructure constructed during Phase I, including access roads, power supply, telecommunication systems and camps, will be used. .

Significant additional works contracts will be awarded for the construction of all-weather access roads, a bulk power supply network, telecommunications systems and project housing, as well as labour camps on both ends of the transfer tunnel.

A permanent housing development will be established near the Polihali dam and transfer tunnel, which will consist of project offices, and residential and community facilities. This will require extensive infrastructure development before the mobilisation of contractors for the two main works contracts of the Polihali dam and transfer tunnel.

The Polihali intake site will use the infrastructure required to construct the Polihali dam and the transfer tunnel. This includes feeder roads and bridges around the reservoir to connect affected communities, power supply systems, construction camps and communications.

The facilities at Katse dam will be used for the Polihali-to-Katse tunnel construction. Existing facilities will be used to house consultants and construction management teams. Improvements to the water and sewage treatment plants, clinic and lodge will be undertaken. A primary school will be built.

The existing camp for construction workers at Mphorosane will be refurbished for use by the Polihali-to-Katse tunnel contractors. Improvements and expansions to the existing water and sewage treatment plants will be required. Other ancillary services will be constructed as determined during the design phase.  A satellite police station and accommodation facilities will be built and manned by Lesotho.

The upgrading of the existing hospital facilities at the Mamahau mission will be investigated and implemented to serve as a jointly managed project hospital, if deemed feasible.

Other infrastructure
In addition to the main access roads to service the construction phase, other access and feeder roads will be constructed around the reservoir to connect affected communities using pedestrian and light-vehicle bridges, while a pair of major road bridges will be built over the Polihali reservoir at Tlhakola, crossing the Khubelu river and near Mokhotlong, crossing the Senqu river.

Environmental measures
Environmental mitigation measures, including flow matters and baseline studies, will be implemented.  The full extent of which is being studied in detail for implementation.

An environmental and social management programme is being implemented to address potential environmental and social impacts associated with Phase II activities. The programme comprises baseline studies, including those pertaining to environmental flow requirements, biological and archaeological (including heritage) studies, as well as socioeconomic and public health studies. The programme also includes environmental- and social-impact assessments, and the implementation of the subsequent environmental and social management and action plans.

Social development programmes
Social development programmes, mitigation measures, resettlement requirements and baseline studies, as well as public relations and awareness campaigns, will be implemented. The full extent of these measures are being studied and discussed. Their implementation will soon be agreed to by the parties to impose the absolute minimum disruption on the affected households and communities.

These infrastructure developments might include medical clinics, feeder roads and bridges around the reservoir to connect affected communities, and social development projects such as schools, churches and community halls.

Pumped-storage scheme
Phase II might also include a pumped-storage scheme, associated transmission lines and works using the existing Katse reservoir as the lower reservoir, and a new upper reservoir in the Kobong Valley. The implementation of the scheme, which is still being debated, is subject to a joint decision by the two governments.

Value
The project is expected to cost R17.5-billion on completion.

Duration
Phase 2 of the LHWP is expected to start supplying South Africa with water by 2023.

Latest Developments
The procurement of consultants for the four-phased, multibillion-rand binational LHWP has signalled the official start of the physical work component of Phase 2 of the project, says LHWP implementing agency the Lesotho Highlands Development Authority CEO Refiloe Tlali, adding that three contracts have thus far been awarded.

Contract 3017, valued at R8-million for the demarcation of the Polihali reservoir, was awarded to the Maseru-based Maleka, Ntshihlele, Putsoa Joint Venture (JV).

Tlali explains that the demarcation entails surveying and constructing beacons around the 250 km perimeter of the Polihali reservoir, 5 m higher than the full supply level. This level allows for a safe margin above the full supply level of the reservoir.

Demarcating the reservoir area is critical for the acquisition of land, resettlement and the compensation of people in the catchment area whose homes and livelihoods will be affected by the construction of the dam. It is also essential for the planning of the Phase II activities, she adds.

Contract 3014, valued at R16-million for the construction of the Polihali north-east access road, was awarded to the SMEC-FMA JV between the South African office of international engineering consultancy SMEC and Lesotho-based civil and structural engineers FM Associates.

This contract involves upgrading the existing road to a standard that allows for the safe movement of construction vehicles during the mobilisation of machinery and facilities for other advanced-infrastructure contractors who will require unhindered access to the Polihali dam site.

Contract 3015, valued at R15.9-million for the supervision of the geotechnical investigations for the Polihali dam and the Polihali-Katse transfer tunnel, was awarded to South Africa-based civil and structural engineering consultants Jeffares & Green, in association with Lesotho-based engineering company GWC Consulting Engineers, says Tlali.

The geotechnical investigations involve the extraction of rock and soil for testing purposes to provide comprehensive data for the dam and tunnel-design consultants. The investigations will also identify the suitability, quality and quantity of construction material at all investigated quarries.

Timeline
Phase II of the LHWP officially started in August 2011, when the governments of Lesotho and South Africa signed the agreement to implement the phase. The agreement was subsequently ratified by South Africa in November 2012 and by Lesotho in May 2013.

“In July 2013, engineering firm CDM International was appointed as the Phase II project manager, which prompted the start of preparatory work for the implementation of the Phase II components,” Tlali elaborates.

She explains that Phase II will include the construction of water-transfer and hydropower components, comprising the construction of the Polihali dam, a 38-km-long water transfer tunnel from the Polihali reservoir to the Katse reservoir, as well as a pumped-storage hydropower scheme. The Polihali dam is the third of five dams proposed for the LHWP.

“The estimated cost of the water-transfer component on completion is R17.5-billion. Further studies for the hydropower component are under way; therefore, the hydropower cost is not confirmed,” Tlali points out.

Advanced infrastructure for the second phase also includes establishing the project housing and dam site, and establishing the Polihali western access road and Polihali reservoir feeder roads, she adds.

Tlali further notes that the dam works of the project will comprise the construction of the Polihali dam. This will entail the construction of a 163.5-m-high concrete-faced rock-fill dam (CFRD) on the Senqu river, a 50-m-high CFRD saddle dam and a concrete side-channel spillway, with an uncontrolled crest length of 100 m, transitioning into a reinforced concrete chute and flip bucket.

The dam works will also include the construction of a compensation outlet, comprising a freestanding reinforced-concrete tower containing a dry well, an access bridge connecting the left abutment with the inlet tower, a compensation outlet house with a potential hydropower station of between 3 MW and 8 MW of installed capacity and a low lever outlet, to be constructed in one of the two river diversion tunnels, says Tlali.

Environmental and Social Management
Phase II of LHWP will also include environmental and social management initiatives to address the potential environmental and social impacts of the project’s construction activities, says Tlali.

This includes baseline studies, such as environmental flow requirements, biological and archaeological studies, as well as socioeconomic and public health studies, which have been completed.

Tlali tells Engineering News that it was necessary to include the social and environmental component in Phase II of LHWP, as a project of this size and complexity has the potential to negatively impact on its surrounding environment, which means proper care has to be taken.

“Lesotho and South Africa need to take all reasonable measures to ensure that the implementation, operation and maintenance of the project are compatible with the protection of the existing quality of the environment and that they pay due regard to maintaining the welfare of the communities immediately affected by the project.”

She adds that households – the exact number of which will be determined during resettlement planning – will be affected by the construction and impoundment of the dam.

Further, it is expected that five villages will fall below the demarcation line and that all households from these villages will need to be resettled.

“However, no families have been relocated as yet,” says Tlali, adding that relocation will begin only once the demarcation of the dam and a health-impact assessment, as well as the environmental and resettlement studies, have been completed.

She adds that there has been extensive engagement with communities in the development of the compensation policy, which is still in draft form.

On Budget and on Time?
Too early to state.

Key Contracts and Suppliers
C4/Seed joint venture (feasibility study); the TCTA (debt management and funding of the water-transfer portion of the project, as well as the operation and maintenance of the delivery tunnel north); Mops Civil (access road); Aecon (construction of measuring weir); Ntshihlele, Putsoa JV (Contract 3017 – demarcation of the Polihali reservoir); SMEC-FMA JV (Contract 3014 – construction of the Polihali north-east access road); and Jeffares & Green, in association with Lesotho-based engineering company GWC Consulting Engineers (Contract 3015 – supervision of the geotechnical investigations for the Polihali dam and the Polihali-Katse transfer tunnel,

Contact Details for Project Information
LHDA public relations manager Masilo Phakoe, tel +266 2224 6000 or email  phakoem@lhda.org.ls.