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Lower Seti (Tanahu) Hydropower Project
Dec 13th, 2021

THL has envisaged to develop Lower Seti (Tanahu) Hydropower Project located about 18 km downstream of the tailrace of Tanahu Hydropower Project. The peaking type ROR project with an installed capacity of 126 MW will have an estimated annual energy generation of 520 GWh with utilization of the flows of Madi River in addition to the regulated discharge of Seti River from the tailrace of Tanahu Hydropower Project.

Under the Grant-0361-NEP, Project Preparation Facility for Energy of the ADB, THL signed a Contract Agreement with JV of WAPCOS Limited, India and Nippon Koei Co. Ltd, Japan on 12 April 2019 for the Detail Engineering Design and Preparation of Bidding Documents of the project. After completion of the field investigation works, the Consultant has submitted the draft design report and bidding documents during the first quarter of 2021.  As per the agreed plan with the ADB, THL has appointed international Panel of Experts (POE) for the independent review of design documents submitted by the Consultant. The POE has commenced the services and has so far submitted the first draft design review report to the THL.

Salient Features of the Project

Project ParticularsDetails
Project LocationProvince (Gandaki Province)
DistrictTanahu
Name of RiverSeti River
Headwork SiteAbout 24 km south from Damauli
Powerhouse SiteGhaighat (about 17 km from Mugling Bazzar)
General    Type of Scheme(PROR)
Full Reservoir LevelEl. 275.0 m
Minimum Draw Down LevelEl. 272.0 m
Normal Tail Water LevelEl. 200.0 m
Minimum Tail Water LevelEl. 198.0 m
Max. Gross Head77.0 m
Min. Gross Head72.0 m
Gross Operating Head75.33 m
Net Head67.05 m
Installed Capacity126.0 MW
Energy after OutageTotal Energy (520.78 GWh)
Wet Energy360.98 GWh
Dry Energy159.80 GWh
(Peak = 122.04 GWh & Off Peak= 37.76 GWh
HydrologyCatchment Area (2,859 sq. km at Intake)
 19,800 sq. km at Power House
Design Discharge206.9 m3/sec
Riparian Release5.08 m3/sec
Design Flood Discharge9071 m3/sec (1 in 500 yrs. return period, n-1 gates)
Design Flood Discharge10,096 m3/sec (1 in 1000 yrs. return period, n gates)
Diversion Structure (Barrage)      Total Width of Barrage(200m at top)
Total width between abutments110.5 m
Total Length of Barrage213 m
Length of Cistern85 m
Nos. of gates6
Width of a spillway bay11 m
Nos. of piers5
Width of a pier6 m
Width of fish pass5m
Width of a fish pass wall1.75 m
Average River Bed ElevationEl. 246.0 m
Under sluice Sill ElevationEl. 248.0 m
Undersluice Opening (W X H)11m x 14m
Barrage Crest ElevationEl. 277.0 m
Cistern ElevationEL. 240.3 m
Power IntakeType of Intake (Side Intake)
Nos of Opening3
Size of an Intake (W x H)20.85 m x 24.5m
Intake Sill ElevationEL.252.5 m
Nos. of piers2
Width of a pier1.62m
No. of Coarse Trash rack3
Size of the trash rack (W x H)5.2 m x 24.5m
Headrace TunnelTunnel Shape
Diameter of tunnel8.25 m (finished)
Length6763 m
No. of Adits along HRT3
Size of Adits (WxH)5.5 m x 7.5 m
Rock Type estimationClass 3 (20%), Class 4 (60%) & Class (5 &6) (20%)
Surge Shaft    Type
Effective Depth55 m
Diameter (Or size)25 m
Dia. Of Restricted Orifice3.5 m
Invert of Surge Shaft231.37 masl
Max. Up Surge Level293.5 masl
Max. Down Surge Level249.5 masl
Normal Operation Level275 masl
Steel Penstock PipeInternal Diameter
Length197 m
Steel Thickness30 mm (varies)
PowerhouseType
Size (L x W)92.0 m x 32.0 m at erection bay
Height47.0 m with steel roof
Turbine Axis Level192.5 masl
TailraceType
Tailrace Length82.0 m draft tube
  
Tailrace Water Level (normal)200.00 masl
Tailrace Water Level (min.)198.00 masl
TurbineType
Number3
Capacity per unit42 MW
Net Head67.05
Turbine Axis Level192.5 masl
Turbine Efficiency94.0%
Generator Efficiency98.5%
GovernorType
Adjustment for Speed DropSpeed sensor
GeneratorType
Rated Output Capacity per Unit52 MVA
Power Factor0.9
Generation Voltage11 kV+-5%
Frequency50 Hz
No of Units3
Transformer 
Rated Capacity52 MVA, 11kV/220 kV
No of Units3
Frequency50 Hz
Transmission LineVoltage Level
LengthAbout 2 km
Conductor TypeACSR Bison
FromLSHP Pothead Yard
ToUSHP-New Bharatpur Substation line in LILO scheme
Project Cost Estimate$ 180 Mil. (Base Cost)
Construction Period5.5yrs