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The Rentembe dam and power station from the most downstream project of a cascade of reservoirs and hydro=power stations on the Mahaweli ganga in the Dumbara Valley. Rhe rantambe dam is located just downsream of the confluence of Uma Oya with Mahaweli Ganga, about 3 kms downstream of the Randenigala dam and 2.5 kms upstream of the Minipe anicut. The primary function of the project is the generation electrical energy using the water releases from Randenigala reservvoir and the natural flow of the Uma Oya.
The Rantambe project consists of a 420 m. long, 42 m. high gravity type concrete dam across Mahaweli ganga and a power station on the left bank having two turbine-generator units of total installed capacity of 52 MW. The gated Spilway, power intake and the steel penstock are incorporated in the dam. The power station is expected to generate 180 Gwh. Of Firm energy and 73 Gwh. Of secondary energy per annum. The switchyard and transmission lines have been already completed under the Randenigala project.

The construction work of the project was commenced in January 1987. Most of the civil construction wok was completed by February 1990. The valuable timber within the reservoir bed was extracted and the reservoir bed cleared of even shrub and stumps, by the State Timber Corporation. The impounding of the reservoir commenced on 2nd February 1990. and the power generating units 1 and 2 were successfully put into commercial operation on 10th March and 10th April 1990 respectively.
Finances

The foreign cost of the project is financed by a loan of 230 Million DM provided on concessionary terms by the Federal Republic of Germany approximating to Rs.3,027 million. Ceylon Electricity Board (CEB) is financing the local component amounting to Rs.1050 million. The project was competed as scheduled in May 1990.

Consultancy services

The consultancy services are provided by Joint Venture Randenigala (JVR) which were a consortium of three consultancy firms namely Salzgitter Consult GmbH. Agrar Und Hydrotechnik GmbH of the Federal Republic of Germany and Electrowatt Enginerring services Ltd., of Switzerland, in association with the Central Engineering Consultancy Bureau (CECB).

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Scope

A dam at Randenigala site consists with two turbaine-generator units of total installed capacity 52 MW and the power station generated 180 GWh of firm energy and 73 GWh of secondary energy.
The Main Physical Components of the Project
The average rainfall within the Rantambe Project area ……… mm.
The Rantambe Project basic parameters :
Dam type concrete gravity

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Recervoir

Catchments area – 3,118 Km 2
Gross storage capacity – 21.0 MCM
Live storage capacity – 4.4 MCM
Surface at retention level – 152.0 m MSL

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Main Dam

Dam Length - 420 m
Dam Height – 0.20 m
Crest elevation – 41.50 m
Crest length - 50 m
Maximum base width -

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Spill way

Maximum capacity – 10,235 m 3/ s
Number of gates - 1
Type of gates - Taintor Type
Hight of gate – 16.21 m
Width of gates – 16.00 m

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Tunnel Bottom & Irrigation Outlet

Design capacity – 300 m3/
Number of turbine & Generator - 2
Type of turbines - Francis type
Setting of turbines - 148.50 m MSL
Installed capacity – 64 MVA
Annual estimated energy
Generation firm - 180 GWh (one million units)
Secondary - 73 GWh
(Sources Projects and Programme 1988)

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Consultancy services

Scope

Recervoir

Main Dam

Spill way

Tunnel Bottom & Irrigation Outlet