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Phase 2 of LHWP in full swing

MEGAPROJECT
The Lesotho Highlands Water Project is a multibillion-rand, binational water project that will benefit Lesotho and South Africa

MEGAPROJECT The Lesotho Highlands Water Project is a multibillion-rand, binational water project that will benefit Lesotho and South Africa

31st July 2015

By: Bruce Montiea

Creamer Media Reporter

  

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The procurement of consultants for the four-phased, multibillion-rand binational Lesotho Highlands Water Project (LHWP) 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.

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 2 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 Joint Venture 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 2 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 2 project manager, which prompted the start of preparatory work for the implementation of the Phase 2 components,” Tlali elaborates.

She explains that Phase 2 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.

The 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 2 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 2 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 there are households – the exact number of which will be determined during resettlement planning – which 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.

Edited by Samantha Herbst
Creamer Media Deputy Editor

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