Polihali Diversion Tunnels, Lesotho

The Polihali Diversion Tunnels project is a fundamental piece of work for the future water supply of Lesotho and South Africa, an area that is subject to frequent droughts that cause severe food shortages. These diversion tunnels are essential for the construction of the Polihali Dam, designed to create a reservoir fed by the Senqu and Kubelu rivers, whose water will be transferred to the Katse Dam reservoir, which already serves South Africa.

To minimise the impact on the land and surrounding communities, the project includes work to improve access roads to allow the safe transport of equipment and heavy materials. In addition, new roads will be constructed to reach the work areas, including a temporary crossing of the Senqu River.

Excavation and construction activities were supported by the construction of an explosives storage facility and temporary camps for personnel and, and in view of the open excavation portals to the intake and outlet canals and temporary flood barriers were provided. Two diversion tunnels were also constructed to divert water flows during the construction of the dam and the intake towers at the entrance of the diversion tunnels, ensuring optimal control of water resources.