Upper Tamakoshi Hydroelectric Plant, Nepal

The project lies at the base of the Higher Himalayas, about 100 km north-east of Kathmandu and 8 km south of the Chinese Tibetan border.

This high head run-of-river project consists of:
– a 60 m long, 22.5 m high concrete dam, topped by an overflow weir
– an open-air desander with two 246 m long settling basins
– power waterways comprising 7,857 m headrace tunnel, 1,560 m steel lined pressure tunnel and shafts and 2,560 m tailrace tunnel
– a powerhouse underground cavern and a transformer underground cavern. Total volume of excavation 75,000 m³
– six Pelton turbine generating units, each with a capacity of 77.5 MW and a nominal flow of 11 m³/s
– a 40 km long double circuit 220 kV transmission line and the upgrading of an existing 75 km long single circuit 132 kV to a 220 kV double circuit transmission line

The project exploits a gross head of 822 m over a 11 km stretch of the Tamakoshi river. A 2 km long intake pond will be formed with a HRWL of  1987 m a.s.l., a total volume of 1.87 million m³ and a pondage (between HRWL of 1987 and 1983 m a.s.l.) of 0.82 million m³. The overflow weir has four bottom outlets, each with a 5 m x 5 m radial gate, which are used to control the water level in the intake pond during the wet season and for flushing of sediments. The intake on the right bank is an integral part of the dam structure and is provided with a 14 m x 15 m trash rack. 

ClientUTKHPL – Upper Tamakoshi Hydropower Ltd a subsidiary of NEA
LocationNepal
Executionsince 2007
Technical Data
  • Plant capacity
456 MW
  • Annual production
2,281 GWh
  • Total estimate cost
650 million US$
  • Turbine type
6 No. Pelton
  • Turbine capacity (per unit)
77.5 MW
  • Gross head
822 m
Services

(Joint Venture with Norconsult)

  • Review and update of previous studies and basic data
  • Detailed field investigations concerning topography, hydrology, sediment transport, geology and geotechnical conditions
  • GLOF study
  • Environment and social studies
  • Detailed tender design of civil, electro-mechanical and transmission works
  • Construction cost estimate, construction planning and scheduling
  • Preparation of tender documents
  • Construction supervision
  • Contracts, Claim and Project Management

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