Kashimbila Hydropower Station
Generation of 40 MW from the Kashimbila hydropower station
The Nigerian government embarked on a policy to increase the country’s hydropower generation capacity to meet its power generation needs. Zutari was first appointed in 2011 to carry out a technical feasibility study of the spillway at the Kashimbila Dam.
This was followed by appointments to carry out the detailed design of the dam, a technical feasibility study of the hydropower station, and, eventually the detailed design of the hydropower station.
This included the development of a 40 MW hydropower station as part of the dam. Subsequent to the successful outcome of this project, Zutari was again appointed to provide the engineering services for the establishment of 240 km of 132 kV double-circuit lattice transmission lines and 40 km of 33 kV double-circuit lattice transmission lines, five new substations, and one major upgrade to the interconnecting substation for power export to the Nigerian transmission grid in 2015.
The preliminary design was done for a dam with a storage capacity of 200 Mm3. A 500 m-wide chute spillway with a long return channel to the river was built on the southern side of the dam. The storage capacity was subsequently increased to 500 Mm3.
The cost of the river diversion works was also substantially reduced
This pushed the spillway into the foothills of the surrounding mountains, which increased the excavation volume to far beyond that required for the embankment. Zutari modified the overall dam design to a composite dam with the spillway located close to the river channel to minimise the excavation for both the approach and the discharge channels.
Zutari also reviewed the flood hydrology and flood attenuation in the dam basin, which reduced the design flood, once again leading to a more economical solution. The cost of the river diversion works was also substantially reduced by replacing the 136 m-long diversion conduits of the original design by 25 m-long diversion culverts through the bottom of the spillway weir.
The main challenges were the lack of data in the hydrological and geological studies as well as the project location in the extreme south-eastern part of Nigeria, which resulted in long travel times on very poor roads.
The hydropower station was initially designed with an installed capacity of 18 MW. However, following the detailed hydrological modelling and yield analysis carried out by Zutari, a 40 MW installed capacity was recommended, which was accepted and implemented. The services included all engineering disciplines, from network planning and modelling, to electrical, civil and structural designs, and building services.
The key functional packages were the network studies, transmission lines for 132 and 33 kV (including the design and development of the new towers and their foundations), the substation civil, primary plant, control plant, supervisory control and data acquisition (SCADA), and telecommunications systems. This project was successfully completed and energised in December 2019.
The support services included procurement support for the establishment of all major supply contracts and the quality management and control associated with these. Zutari was also responsible for quality control and support through the construction, commissioning, and handover stages.
Zutari’s input on this project led to a more economical design of the dam and an increased installed capacity for the hydropower station.
Zutari’s input on this project led to a more economical design of the dam and an increased installed capacity for the hydropower station.
*The Aurecon Africa business has been officially renamed Zutari as at 21 July 2020. Zutari acquired Aurecon Middle East on 20 November 2020.
