In the early 70s TANZANIA ELECTRIC SUPPLY COMPANY LIMITED (TANESCO) embarked on implementation of the Great Ruaha Power Project (GRPP) which was implemented in three phases. Completion of the project represented a major hydroelectric development in Tanzania. The project was undertaken by Tanzania Electric Supply Company Limited (TANESCO), and the Swedish Consulting Group (SWECO) provided consulting services for the project.
PHASE I (1970-1975)
Phase I of the project involved the construction of a 40m high and 350m long earth rock fill dam and an underground power plant at Kidatu installed with two generating units each with a capacity of 50MW totaling 100MW. The rock fill dam located about 10km upstream of the underground power house created a regulation reservoir for the plant with storage capacity of 125 million m3 and unlined headrace intake tunnel of 9.6km long down to the power station.
PHASE II (1977-1981)
Phase II of the project consisted of additional installation of two 50MW units at Kidatu Hydro Plant, thus bringing the ultimate capacity of the plant to 200MW. However, it was realized that the Kidatu Reservoir volume was too small for annual regulation and for continuous operation of the four generating units. To take care of the water availability during the dry season of normal years as well as a series of dry years, adequate storage had to be provided upstream of Kidatu. It was from this reason the idea to construct a main storage dam about 170km upstream of Kidatu at Mtera was conceived.
PHASE III (1984-1988)
Phase III of the project comprised the construction of an underground power plant at Mtera, installation of two generating units each of 40MW, totaling 80MW. Close to the dam there is a water intake for a short headrace tunnel and penstocks to the power house, before the water is discharged back via a long tailrace tunnel.
THE MTERA DAM AND POWER STATION
Mtera Dam is the largest dam in the country in terms of height, crest length and concrete volume. Its impounded reservoir is also the largest man-made lake in Tanzania. The Dam is also the road bridge between the Iringa and Dodoma regions and is part of the Great North Road (Cape Town to Cairo).
The Mtera Dam is a concrete structure of the buttress type with crest level at 701.5 metres above sea level. The main tributaries to the dam are the Great Ruaha, Little Ruaha and Kisigo Rivers. The Dam was completed in December 1980 and was inaugurated by the late President Mwalimu J.K.Nyerere on 19th February 1981.
Mtera Hydropower Plant has an installed capacity of 80MW. The power generation started in 22nd May 1988 for unit 1 and 7th December 1988 for unit 2 respectively.
|Catchments area (km2)||68,000|
|Maximum height of the Dam (m)||45|
|Total crest length (m)||260|
|Full Supply level (m.a.s.l)||698.5|
|Minimum Supply level (m.a.s.l)||690.0|
|Area at F.S.L. (km2)||605|
|Area at M.S.L (km2)||187|
|Live storage volume at F.S.L (Mm3)||3200|
|Dead storage volume at M.S.L (Mm3)||500|
|Headrace tunnel length (km)||0.8|
|Tailrace tunnel length (km)||11.5|
|Vertical Steel penstocks (km)||0.92|
|Total generation capacity (MW)||80|
|Firm annual generation (GWh)||303|
|Number of units||2|
|Cross Section of Headrace and Tailrace (m2)||55|
|Discharge capacity through Turbines (m3/s)||96|
Contract for the Works
For the construction of the Mtera Power Plant the following Contracts were awarded during March, 1984.
|Civil works ||IMPRESIT, COGEFAR, Sesto San, Giovanni, Milan, Italy|
|Penstock steel ||ABB SAE SADELMS,|
|Linings and gates||Milan Italy|
|Turbines, pipe works and crane ||KVAERNER ENERGY A/S Oslo, Norway|
|Generators||ABB GENERATORI SRL Giovanni Sesto San Milan Italy|
|Transformers||EB NATIONAL TRANSFORMER A/S Drammen, Norway|
|Electric Equipment ||ASEA BROWN BOVERI AG, Mannheim, Federal Republic of Germany|
|Consultant Engineer||SWECO Stockholm, Sweden|
|FINANCIERS.||IDA, KfW, SIDA, MCC, KFAED, NORAD and TANZANIA GOVERNMENT|