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The Rehabilitation of the Mt Coffee Hydropower Project in Liberia

By WD Hakin, Dr QHW Shaw, Richard Guimond and Bentle Taraldsten-Brunes.

The Mt Coffee Hydropower Project was brought into commission in 1967 and successfully generated approximately 20% of Liberia’s electricity requirements until 1990 when, during the first of two civil wars, the dam was overtopped and eventually breached over a length of approximately 180 m. The dam breach occurred due to the culmination of a sequence of events that ultimately prevented the operators from gaining access to utilise an emergency generator to open more spillway gates. The powerhouse, which housed four Francis turbines with a total installed capacity of 64 MW at the time, was flooded and later stripped of all its mechanical and electrical equipment.

 This paper provides insight into the particular circumstances that resulted in scheme failure and the approach taken to identify the optimal design for project rehabilitation. The authors discuss the approach taken for the design of the spillway system, dam embankment, powerhouse and associated works taking into account the competing aspects of cost constraints, dam safety and the prevailing social, political and environmental factors.