English
Nepali
Tanahu Hydropower Project is located on the right bank of Seti River, about 150 km West of Kathmandu near Damauli, the district headquarters of Tanahu District. This is the storage type project, which is planned to have an installed capacity of 140 MW with an estimated annual energy generation of 502.5 GWh. The Project is designed for at least six hours of peaking operation during the driest month of the year.
The project area covers 2 municipalities (Vyas and Bhimad) and 2 rural municipalities (Rhising and Maygde). The Vyas Municipality, with Damauli Town as district headquarter of Tanahun district, is a major urban settlement. The reservoir will extend about 25 km upstream inundating the low-lying lands (415 m) along the Seti River. The Project also include Rural Electrification (RE) and Transmission Lines (TL) component. A new 220 kV double circuits TL will evacuate the generated power to the new Bharatpur Substation. The length of the transmission line corridor is 37 km.
THL signed the contract agreement with M/S Lahmeyer International in association with Manitoba Hydro. International, Canada (“the Consultant”) as Project Supervision Consultant (PSC)on June 29, 2015. The contract period of PSC is twelve years. The consultant will assist one year for pre-construction activities, six years for project construction and last five years for project operation and maintenance.
Major Construction Packages
The Contract Agreement for the construction of Work Package 1 (Dam and River Diversion) was signed on 22 March 2021 with the M/S Song Da-Kalika JV. Likewise, the Contract Agreement for Work Package 2 (Waterway, Powerhouse and Related Equipment) was signed between the THL and M/S Sinohydro Corporation Limited, China on 1st October 2018. For the execution of Work Package 3 (Transmission Line), THL signed Contract Agreement with M/S KEC International Limited, India on 25th December 2018.
Panel of Experts
THL signed the contract agreements for the Panel of Experts (POE) for dam safety, environment, and social safeguards (DSE) on 17th December 2018. The primary responsibility of the DSE member of the POE is to provide independent review of project documentation (technical, environmental and social assessments, EMPs, environmental monitoring on the treatment of safety issues associated with the dam.
Financial Arrangement
The Project is jointly financed by Asian Development bank (ADB), Japan International Cooperation Agency (JICA), European Investment Bank (EIB), Government of Nepal (GoN) and Nepal Electricity Authority (NEA). Loan agreement for an amount of US$ 150 million was signed with ADB on February 21, 2013. Similarly, loan agreement for an amount of US$ 184 million was signed with JICA on March 13, 2013 and loan agreement with European Investment Bank (EIB) was signed on May 7, 2013 for an amount of US$ 70 million, which further increased to 85 million. Fund from GoN and NEA will be used for the preparation of preconstruction infrastructures activities.
Salient Features of Tanahu Hydropower Project
| Project Particulars | Details |
| Reservoir | Full Supply Level (415.0 m) |
| Minimum Operation Level | 378.0 m |
| Available Depth | 37.0 m |
| Sedimentation Level | 320.0 m |
| Gross Storage Capacity | 295.1 × 106 m3 |
| Effective Storage Capacity | during first 10 years; 192.8× 106 m3 after 11th years; 181.7 × 106 m3 |
| Diversion Tunnel | Design Flood 2,305 m3/s (20 years return period) |
| Number and Type of Tunnel(2, concrete lined pressure flow) | |
| Length(606 m and 666 m) | |
| Inner Diameter(10 m) | |
| Dam | Type(Concrete gravity) |
| Elevation of Dam Crest | 420.0 m |
| Height of Dam | 140.0 m |
| Length of Dam Crest | 215 m |
| Volume of Dam | 929 × 103 m3 |
| Auxillary Dam | Type(Weir resting on bore piles wall) |
| Length of Crest(133 m) | |
| Height(30.6 m) | |
| Volume(121,980 m3) | |
| Sediment Flushing Facilities | Inlet Sill Elevation(320 m) |
| Gradient of Conduit | 1: 15 |
| Upstream Maintenance Gate Span x Height | Slide Type Steel Gate 5 m x 5m |
| Intermediate Main Gate Span x Height | High Pressure Slide Gate 5 m x 5 m |
| Downstream Auxiliary Gate Span x Height | High Pressure Slide Gate 5 m x 5.2 m |
| Spillway | Design Flood (7,377 m3/s) |
| Type | Chute |
| Elevation of Overflow Crest | EL. 398.1 m |
| Width of Overflow Crest | 51.32 m |
| Energy Dissipater | Roller bucket |
| Type of Gate | Radial (4 Nos.) |
| Size of Gate (span x height) | 12.83 m x 18.1 m |
| Intake | Number : One(1) |
| Intake Type | Tower Type Intake |
| Gate Type | Vertical Lift Fixed Wheel Type Steel Gate |
| Size of Gate (span x height) | 6 m x 9 m |
| Headrace Tunnel | Number: One (1) |
| Inner Diameter | 7.4 m |
| Total Length | 1469.6 m |
| Surge Shaft | Type (Restricted Orifice) |
| Shaft Height/Diameter:28 m/ 61.5 m | |
| Diameter/Height of Riser: 7.4 m/22.8 m | |
| Diameter of Orifice:5 m | |
| Penstock | Type: Tunnel |
| Number | One (1) |
| Inner Diameter | 5.7 m to 4 m |
| Total Length | 160 m (including one (1) branch pipe length) |
| Draft Tunnel | Length: 99.4 m |
| Type of Draft Gate | Vertical Lift Slide Type Steel Gate |
| Size of Draft Gate (span x height) | 5 m x 3.1 m |
| Tailrace Tunnel | Diameter: 7.4 m |
| Length | 213 m |
| Outlet | Outlet Type: Outlet with Draft Pond |
| Type of Tailrace Gate | Vertical Lift Slide Type Steel Gate |
| Size of Tailrace Gate (span x height) | 7.4 m x 7.4 m |
| Powerhouse | Type: Underground |
| Size: 22 m wide × 45 m high × 89 m long | |
| Development Plan | Rated Intake Water level: 405.0 m |
| Tail Water Level | 289.2 m |
| Gross Rated Head | 115.8 m |
| Maximum/Rated Effective Head | 121.55 m/111.7 m |
| Maximum/Rated Discharge | 131.2 m3/s /127.4 m3/s |
| Number of Unit | Two (2) |
| Install Capacity | Rated capacity; 127 MW Maximum capacity: 140 MW |
| Peak Time | 6 hours |
| Primary Energy | 178.9 GWh |
| Secondary Energy | 323.6 GWh |
| Total Energy | 502.5 GWh |
| Turbine | Type :Vertical Shaft, Francis Turbine |
| Number | Two (2) |
| Maximum/Rated Output | 71,800 kW/64,700 kW |
| Revolving Speed | 300 min-1 |
| Generator | Type: Three-phases, Synchronous Generator |
| Number | Two (2) |
| Maximum/Rated Output | 82,300 kVA/74,700 kVA per unit |
| Revolving Speed | 300 r/min |
| Frequency | 50 Hz |
| Rated Voltage | 13.2 kV |
| Power Factor | 0.85 lag |
| Main Transformer | Type: Indoor, special three-phase, Forced-oil-circulated and forced-water-cooled |
| Number | Two (2) |
| Maximum/Rated Output | 82,300 kVA/74,600 kVA |
| Rated Voltage | Primary 13.2 kV |
| Secondary 220 kV | |
| Switchyard | Type: GIS (Gas Insulated Switchyard) |
| Bus System | Double Buses |
| Number of Bays | Five (5) bays |
| Voltage | 220 kV |
| Generation Facility for Environmental | Rated/Maximum Effective Head :93 m/103.3 m |
| Discharge | 2.4 m3/s |
| Flow | Turbine Type: Horizontal Type, Francis Turbine |
| Number of Turbine/Generator | One (1) |
| Turbine Rated Output/ Maximum Output | 1,900 kW /2,100 kW |
| Generator Type | Horizontal Type, Three-phase Synchronous Generator |
| Rated Generator Capacity | 2,300 kVA |
| Distribution Transformer | 3-Phase Dry Type, Rated Capacity 2,305 kVA |
| Average Energy | during first 10 years; 14.0 GWh after 11th years; 13.0 GWh |
| 220 kV Transmission Line | Conductor Type: 380 mm2 × ACSR (Bison) |
| Number of Circuit | Two (2) |
| Voltage | 220 kV |
| Length | 36.9 km |
| Type of Transmission Tower | Steel lattice tower |
| Number of Steel Tower | 94 |
| 220 kV Bharatpur Substation | Number of Bays:Five (5) bays, of which Two (2) bays for transmission lines, Two (2) bays for interconnection to 132 kV substation, and One (1) bay for bus coupler |
| Interbus Transformer | Capacity 83,300 kVA x 2 units Primary 220kV, Secondary 132 kV and Tertiary 11 kV |