The Lesotho Highlands Development Authority (LHDA) has awarded the engineering design and construction supervision contract for the Oxbow Hydropower Scheme – Lesotho’s preferred option for the Lesotho Highlands Water Project (LHWP) Phase II hydropower component.

The successful bidder is a multinational joint venture comprising Lesotho, South African and international firms, and includes France-based Artelia, Australia-based SMEC International, SMEC South Africa and Lesotho-based GWC Consulting Engineers.

The 92-month, R824-million contract marks the first stage of the LHWP Phase II hydropower scheme, and the next step in the process of securing an independent electricity source to meet Lesotho’s growing electricity requirements and reduce the country’s dependence on electricity imports.

“Phase II of the LHWP includes further investment in Lesotho’s hydropower generation infrastructure as specified in Article 8 of the Phase II Agreement. This contract award for the design of the Oxbow Scheme is the first step in that process,” said LHDA CEO Tente Tente.

The Oxbow Scheme, located on the ‘Malibamats’o river, will include a 100-m-high gravity dam, a 6.6-km-long, 3.6-m-diameter headrace tunnel discharging through a high-pressure steel penstock into the 80 MW surface powerhouse.

Evacuation of power will be through a double circuit 132 kV transmission line linking with the ‘Muela substation.

The generation discharge will be conveyed through a 4.2 km tailrace tunnel to the ‘Muela reservoir to ensure that the dammed water is put back into the LHWP for onward delivery to South Africa.

The preliminary design will consider further optimisation by adding a 10 MW powerhouse at the end of the ‘Malefiloane tailrace tunnel to take advantage of the residual 100 m head available.

“Although physically separate from the ‘Muela hydropower plant, which was constructed during Phase I, the two schemes are complementary. Working as a peak plant for about seven hours a day, Oxbow’s 80 MW capacity will add to ‘Muela’s installed capacity of 72 MW,” Tente explained.