Lesotho Highlands Water Project: design and layout of underground works for ’Muela Hydropower Project

Abstract

The paper describes the design of the underground works for the’ Muela Hydropower project which is part of the multi-purpose Lesotho Highlands Water Project which diverts water from the Kingdom of Lesotho through a series of reservoirs and tunnels being constructed in a series of phases.

The’ Muela project, for construction of the first major power station in Lesotho, is being incorporated in the first stage of the scheme currently under construction and the paper describes the inter-relationship between power generation and water delivery elements together with the constraints imposed on the design and implementation of the tunnels and underground powerhouse.

Geotechnical aspects specific to the project are reviewed and the testing and investigation programmes carried out are summarised. Although design methods follow largely orthodox lines, specific features of the excavations and linings required to meet the particular conditions of the site are noted.