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Dordi Khola Hydropower Project (27 MW)

Salient Features of the Project:

Location
Country Nepal
District Lamjung
Development Region Western
Location of Intake and Project site Chiti VDC
Nearest Airport Pokhara
Geographical Co-ordinates of Project Area
Longitude 84° 26’E to 84° 28’30”E
Latitude 28°10’ N to 28°13’ 32”N
Hydrology
River/Stream Dordi-Khola
Catchment area at Diversion site 277 km2
Design Discharge 15.28 m3/s
Design Flood at diversion site (100 year return period) 614 m3/s
Design Flood at Powerhouse site (1000 year return period) 3251 m3/s
River Diversion Arrangement
1 in 20 years dry season design flood 27.24 m3/s
Top of coffer dam at upstream El. 762.0 m
Top of coffer dam at downstream El. 756.0 m
Diversion Structure
Type Ogee Type weir, free over flow with under sluice bays
Average river bed level El. 758.0 m
Bridge deck level El. 768.0 m
Width of diversion structure 55 m
Highest flood level El. 767.75 m
Full supply level El. 764.50 m
Weir
Crest elevation of overflow weir El. 764.75 m
Width of overflow weir section 41.2 m
Under Sluice Bay
No. of under sluice bays 2
Width of each bay 4.25 m
Thickness of pier 1.5 m
Crest level of under sluice bay El. 758.0 m
Clear width of under sluice bays 8.5 m
Type and height of gate Vertical gates, 3 m high.
Energy Dissipation System Hydraulic Jump Type Stilling Basin
Length of stilling basin from toe of sloping glacis 25 m
Total width of basin 49.725 m
Cistern level El. 754.0 m
End Sill Level El. 757.0 m
Intake Structure Side Intake
Type 4.75 m (W) x 4.0 m (H)
Track rack size
Numbers of trash rack 2
Intake diversion flow (including 20% flushing discharge) 18.33 m3/s
Intake size Two bays; each 2.25 m (W) x 2.7 m (H)
Invert level of Intake El. 760.50 m
Intake stop log 1 no. Vertical lift gate (2.25 m x 2.7 m)
Intake service gate 2 nos. Vertical lift gate (2.25 m x 2.7 m)
Feeder Pipe
Type Circular steel
Numbers 2
Size 2.25 m Dia.
Length 131.30 m & 140.10 m
Desilting Basin
Type Hopper Type
Numbers of chambers 2 nos
Size of particles to be removed 0.2 mm and above
Dimension (L x B x H) 60 m x 8.5 m x 8.0 m
Design discharge 18.33 m3/s
Flow through velocity 0.26 m/s
Silt Flushing Pipe
Type Circular
Dia 0.9 m
Total length 100 m
Water Conductor Pipe
Type Steel Pipe
Size 2.65 m dia
Total length 3282 m
Head Race Tunnel (Concrete Lined)
Type & shape Underground, D-shaped
Dia 3.3 m
Total Length 2661.67 m
Steel Lined Tunnel
Type & shape Underground, circular
Dia 2.65 m u/s of HRT, 2.3 m d/s of HRT
Total length 25 m, 82 m respectively
Surge Shaft
Type Restricted orifice type
Height 45 m
Dia 7 m
Orifice size 1.3 m dia, circular
Top of surge shaft El. 780.0 m
Maximum upsurge level El. 778.06 m
Minimum down surge level El. 746.39 m
Valve House
Type Surface
Number 1
Size ( L x W x H) 16 m x 9.5 m x 12 m
Type of valve Buttery valve
Diameter of valve 2.3 m
Penstock
Type Surface and Buried Penstock
Nos. One no. starting from outlet portal and trifurcating before Power House.
Diameter 2.3 m, circular shaped
Liner thickness 10 mm to 20 mm
Length 830.5 m
Length of penstock after trifurcation 163.8 m
Branch penstock Circular, 1.3 m diameter each
Power House
Type Surface
Gross Head 214 m
Rated Head 203.32 m
Design discharge 15.28 m3/s
Normal Tail water Level El. 552.0 m
Center line of penstock El. 550.45 m
Size of Powerhouse at machine floor 44.225 m (L) x 15.0 m (W) x 31.25 m (H)
Tail Race Channel
Type RCC Box culvert
Length 333.66 m
Size 3.5 m x 2.5 m
Normal tail water level El. 552 m
Switchyard
Size 30 m x 40 m
Voltage level 132 kVA
Turbine
Turbine Type Horizontal axis Francis
Number 3
Rated Capacity of each turbine 9.3 MW
Governor
Type Electro-Hydraulic
Generator
Generator Type Synchronous three phase
Number 3
Rated Capacity 3 x 10590 kVA
Power Factor 0.85
Voltage 11 kV
Frequency 50 Hz
Excitation system Brushless/ static
Transformer
Rated capacity Bank of 3 x 10.67 MVA, 11/132/√3, single phase
Voltage ratio 11 kV/ 132 kV
Transmission Line
Voltage level 132 kV Single Circuit
Length 1.2 km
Power Generation
Installed capacity 27 MW
Net annual energy after transmission & outage losses 142.75 GWh

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