The Gitaru run-of-river plant, which was commissioned in 1978, comprises an underground powerhouse near the left abutment equipped with three generating units with an installed capacity of 225 MW, and a 30 m-high rock- and earthfill embankment dam, which impounds a reservoir with a maximum capacity of 16 x 106m3 and a spillway capacity of 4500 m3/s.
The relatively small reservoir relies on steady releases from the Masinga and Kamburu dams upstream. The maximum flow rate for each of the three units is 69.4 m3/s. The station has three intake shafts with 4.2 m diameters. These intake shafts are opened or closed by a set of three intake gates which are hydraulically operated. During high water level seasons, the spillway gates must be operated to reduce the water volume in the reservoir to ensure the safety of the dam. During such operations, the gates have been frequently malfunctioning sometimes, failing to open. This was because of the failure of some hydraulic components in the hydraulic control system, as well as shifting of the gates in the horizontal direction causing the gates to jam on the pier. The intake gates have two hydraulic power units, each of which by design can operate all the three gates. During maintenance, the intake is closed as an isolation to allow work to proceed downstream at the main inlet valve and the turbine. Most of the hydraulic components relating to the hydraulic control system of the gates (intake and spillway) are no longer available on the market. KenGen therefore intends to refurbish the hydraulic control systems to update the components to those that can be found on the market in case of any future failures.
The scope of works will cover:
- The refurbishment of the intake gate hydraulic control systems, existing spillway gate and intake gate hydraulic cylinders, and, spillway gate hydraulic control systems.
- The supply, installation, and commissioning of new LV switchboards for the intake gate and spillway gate, and the supply of spares, tools and maintenance equipment.
- The provision of training.
In fulfilment of the contract, the contractor will also be required to carry out: studies of the existing systems; design and engineering services; the dismantling of existing systems; erection and installation of new equipment; and, civil works that may be necessary during site work. All equipment/components to be supplied must have spares available for the next 10 years after installation.
The contracted works need to be completed within 24 months from the commencement date. The refurbishment must be carried out in such a way that there will be continuity of operation under all working conditions and to facilitate inspection, maintenance, and repairs.
The contract will be valid for 36 months, inclusive of the defects liability period. There will be a mandatory site visit on 29 June.
For further information, contact:
Office of the Supply Chain Director
KenGen, Stima Plaza Phase III
Kolobot Road, Parklands
PO Box 47936-00100
Tel: +254 20 36 6000
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