Randenigala Reservoir /Dam
The Randenigala Project, the fourth major multi-purpose project and the largest reservoir under the Accelerated Mahaweli Development Programme. Randenigala project is located about 26 km. below the Victoria Head works and 6 km. upstream of Minipe anicut from where the main Right Bank and Left Bank canals will divert the Mahaweli waters for irrigation. It is also the reservoir with the largest storage capacity having gross storage of 860 million cubic metres (697,000 acre ft.) at full supply level. The project is expected to generate about 525 GWh of electrical energy which amounts to 20% of the island’s present demand. It will serve as the most important base reservoir for water management in System ‘A’, ‘B’ and ‘C’.
The project chiefly consists of the construction of a 94 m.(308 ft) high, 485 m.(1590 ft.) long Rock-fill dam across Mahaweli, created a reservoir of 860 million cu.m. (697,000 ac.ft.). The Power House on the Left bank immediately downstream of the dam has an installed capacity of 126 MW. A steel lined tunnel 6.2 m. dieameter, 270 m. long, convey water to the Power House to run the turbines. The triple gated chute spillway is 48 M. wide, about 232m. long and is capable of discharging the probable maximum flood of 8085 cumecs.
The total cost of these Headworks is approximately Rs. 4898 million of which Rs. 1207 million is the local component and Dautsche Marks 410 million is the foreign component in 1985. The Federal Republic of Germany first granted a loan for a value of about DM 240 million (Rs.2160 million) and has extended a loan to the value of DM 400 million on favourable terms for Randenigala Project. (Rs. 2,528,455 as at the balance sheet 2004) (Rs.’000)
consultants for the Project is Joint Venture Randenigala (JVR), a
firms, Salzgitter Consult GmbH, Agrar-Und Hydro-technik GmbH and
Electrowatt Engineering Services Ltd along with the Engineers of the
Central Engineering Consultancy Bureau. (CECB)
A dam at Randenigala site with power station and other appurtenant structures together with a lower dam at Rantembe (immediately below the confluence of the Uma Oya with the Mahaweli ganga), and power station.
The Main Physical Components of the Project
The average annual rainfall within the Randenigala Project area ranges from 1250mm to 3000 mm.
The Randenigala Project basic parameters :
Dam type Rockfill with Claycore
(As at Projects & Programme 1988)
Dam Length -
capacity - 8,100 m 3/ s
Tunnel Bottom & Irrigation Outlet
Length - 5646
turbine & Generator - 2