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This project aims at harnessing the water resources of the Lesotho highlands by building numerous dams and tunnels. Phase II includes the construction of a dam, transfer tunnel, and associated infrastructure. The Polihali diversion tunnels were initially set up as part of a construction contract to allow for early river diversion in the main Polihali Dam contract.
Dlubal customer Zutari (Pty) Ltd. carried out, among other things, structural analysis of the reinforced concrete inlet structures. Zutari's engineers utilized the RFEM finite element program.
Structure
An optimal solution was developed, including two D-shaped tunnels with diameters of 22.97 ft and 29.53 ft, respectively, and lengths of approximately 0.62 mi each. The tunnels are provided with inlet structures made of reinforced concrete and equipped with stoplog guides, transitioning from a rectangular section to a circular section.
Further transition to the D-shape of the tunnel was constructed using a combination of mass concrete and shotcrete.
The tunnels were excavated using a drill and blast method, full-face, and lined with shotcrete and mesh.
| Location | Mokhotlong, Lesotho |
| Owner | Lesotho Highlands Development Authority (LHDA) |
| Planning | Metsi a Senqu-Khubelu Consultants (MSKC) Joint venture between Zutari, Knight Piesold, Hatch, SMEC, and FM Associates |
| Construction | SCLC Polihali Diversion Tunnel Joint Venture Joint venture of the South African branches of CMC di Ravenna, Salini Impregilo, CMI Infrastructure, and Lesotho-based LSP Construction |
