DAMS & RESERVOIRS
Behind the scenes of the Kashimbila Multipurpose Dam The construction of the Kashimbila Multipurpose Dam has had a significant positive impact for Nigeria and is one of its key showcase presidential projects. The benefits to the local community have been immense and range from job creation to potable water supply, electrification, and an improved transmission network.
Kashimbila Multipurpose Dam at full flood
T
he preliminary design of the Kashimbila Multipurpose Dam on the Katsina-Ala River in the Taraba state in Nigeria was initially focused solely on the dam’s functioning as a buffer in case the natural embankment of Lake Nyos in Cameroon failed. Lake Nyos is a volcanic crater lake around which the ash embankment has been moving and settling. Should the embankment fail, the extreme flooding that would follow would endanger the lives of a significant portion of the people in south-eastern Nigeria. As the design process progressed through a more holistic and multipurpose approach, the capacity of the dam was increased to provide irrigation and potable water to the surrounding towns and villages, as well as for the generation of hydropower. The Nigerian government appointed SCC (Nigeria) Ltd to design and construct the flood protection dam, which was subsequently changed to provide a multipurpose use. SCC appointed Zutari to review the concept design of the spillway proposed by the Federal Ministry of Water Resources before later appointing them to conduct the detail design of the dam. Following discussions with the various stakeholders, Zutari proposed several optimisations to the project, which resulted in
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IMIESA January 2021
Kashimbila Multipurpose Dam during construction
a safer, more affordable, and better optimised solution for all parties. These included an increase in the capacity of the proposed 6 MW hydropower generation to 40 MW, as well as optimised routing of the transmission line to improve the electricity network and distribution in eastern Nigeria. The full project included: • a 36 m high composite dam (clay core rockfill and concrete gravity spillway) • a 40 MW hydropower station and associated substation capable of releasing 260 m3/s (four units, each with a rated flow of 65 m3/second) • the Kashimbila substation equipped with two 30 MVA triple winding transformers to connect the four generators as well as two 15 MVA for the local rural electrification supply • a 132 m long bridge to connect the two riverbanks • outlet works for the irrigation supply, potable water supply, and river releases • 210 km long double-circuit 132 kV transmission lines with OPGW with lattice towers • 45 km long double-circuit 33 kV transmission lines with OPGW with lattice towers • 45 km of 33 kV reticulation network supplying
PROJECT TEAM Ultimate client: Nigerian Federal Ministry of Water Resources and Federal Ministry of Power Zutari’s client: SCC (Nigeria) Professional team: Zutari Main contractor: SCC (Nigeria)
multiple small towns and villages in the surrounding areas with electrical supply • two new 60 MVA 132/33 kV substations • two new 15 MVA 33/11 kV substations • rehabilitation and upgrade of the 132/33 kV Yandev substation where the new Kashimbila line interconnected to the national transmission network • development of a 2 740 ha commercial irrigation scheme comprising centre pivots and flood irrigation.
Optimising the project Zutari’s innovative, creative and out-of-the-box thinking led to several changes in the initial concept of the project. These changes resulted in a multipurpose project that better serves the people of Nigeria and the communities in the area of the project.
