Salient Features

General

Name of Project Nalsing Gad Storage Project
District Jajarkot
Location of project site 82°14'00"E-82°19'12''E
Longitude 28°47'28"N-28°58'00"N
Name of the River Nalsyagu Gad River
Type of Scheme Storage
Project Road 25 Km

Geology

Dam Site Dolomite with frequent intercalation of black Shale
Tunnel Limestone, Dolomite and   Shale
Powerhouse Sandstone
Seismic Survey 58 Profiles – Total 8165 meter
Core Drilling 14 Holes – Total 602 Meter

Hydrology

Catchment Area (up to Dam site) 571.5 Km²
Average Precipitation 1718 mm
Average Monthly Flow 29.35 m³/s
Flood Discharge (1 in 20 year wet season) 675 m³/s
Flood Discharge (1 in 10,000 year wet season) 2244 m³/s
Probable Maximum Flood (PMF) 4488 m³/s
Sediment Yield 3960 t/km²/year

Diversion Tunnel

Shape Circular Shaped
Type Concrete Lined
Diameter 8.0 m
Length 1145

Reservoir

Full Supply Level (FSL) 1570 masl
Minimum Operating Level (MOL) 1498 masl
Total Storage volume 419.6 Million m³
Live Storage Volume 296.3 Million m³

Dam

Type Ogee shaped, non gated side channel
Maximum Height above Foundation 200m
Crest Elevation 1580.30 masl
Length of Crest 545.00 m
Width of crest 10 m

Spillway / Gated Spillway

Type Ogee Shaped ,open chute way with gate controlled weir, flip bucked and plunge Pool
Design Flood (1 in 1000 years) 1510 m³/s
Overflow Crest Elevation EL.1555.30
Effective overflow Width 24m
Length of Spillway Chute 420.00m
Length of Plunge Pool 170 m
Radial Gate (No. and W ×H) 2 Nos. (12.0 m × 18.0m)

Side Spillway / Emergency Spillway 

Type ogee shaped, non gated side channel overflow weir
Design flood (1 in 1000 years) 1510 m³/s
Overflow Crest Elevation EL.1555.30 masl
Effective overflow Width 120 m

Main Intake 

Type Sloping
Deck Level 1575 masl
Intake Tunnel 1 No.
Invert level of  intake 1481.0 masl
Intake Openings 6 Nos.(5.0m×3.5m)

Headrace Tunnel

Length 8215 m
Type Concrete lined modified Horse Shoe
Finished Diameter 5.7 m

Surge Tank

Type Restricted Orifice
Height 171.97 m
Diameter 12.0
Max Water Level 1607.30 masl
Min Water Level 1454.12 masl
Top level 1610.97 masl
Invert Level (of tunnel below surge tank) 1439.00 masl

Inclined Shaft

Shape Circular
Inclination 60°
Height 564 m in two stages
Diameter 4.2 m
Length 900m

High Pressure Tunnel

Type Steel Lined Penstock
Length 90m
Finished Diameter 3.9 m

Powerhouse 

Type Steel Line Penstock
Length 90m
Finished Diameter 3.9 m

Powerhouse 

Type Under Ground
Size (L× W ×H) 106 m × 13m × 31 m
Tail Water Level (turbine pit) 867.6 masl

Turbine 

Type of Turbine Vertical Axis Pelton Turbine
Number of Units 4 No
Turbine Centre line level 872 masl
Installed Capacity 410 MV (4× 102.5 MW)

Tailrace 

Shape Inverted D shaped
Type Concrete Lined
Size (W × H) 4.5 m × 3.5 m
Tail Water Level ( at outlet) 863.3 masl

Transmission Line

Length 112 km
Voltage 400k V
Circuit Double
Interconnection Point Kohalpur S/S

Power

Maximum Gross Head 698.0 m
Designed Net Head 635.5 m
Maximum Net Head 684.36m
Minimum Net Head 612.11m
Design Discharge 75.0 m³/s
Maximum Power Flow 77.92 m³/s
Overall Efficiency 87.80 %
Maximum Daily Generation 12 equivalent hrs
Minimum Daily Generation 2 equivalent hrs
Installed Capacity 410 MV

Energy

Dry Season Energy (November to April) 643.29 GWh
Wet Season Energy (May to October) 150.88 GWh
Spill Energy 611.89 GWh
Total Energy 1406.06 GWh
Regulated Energy 56.19%
Plant Factor (Spill Energy not Considered) 22.11%
Discharge Utility Factor (Spill Energy not Considered) 53.83%
Plan Factor (Inclusive of Spill Energy) 39.15%
Discharge Utility Factor (Inclusive Of Spill Energy) 98.09%

Project Cost

Total Project Cost (Base Cost) 737.39 MUS$(2012 Price Level)
Local Component 157.75 MUS$(2012 Price Level)
Foreign Component 579.64 MUS$(2012 Price Level)
Installation Cost 1799 US$ per kW

Financial Indicators

Total Project Cost (Base Cost) NRs. 64153.19 Million (At exchange rate of NRs. 87.00)
Final Cost ) NRs. 108,263.74 Million
Total Debt NRs. 26,665.66 Million
Interest Rate on Debt 8.0%
Expected Return on Equity NRs. 64153.19 Million (At exchange rate of NRs. 87.00)
Average Energy Cost (for 14% return on equity) Nrs. 9.11/KWH for Total Energy (2012 Price Level)
Average Energy Cost (for 14% return on equity ) NRs.16.09/KWh for saleable Energy (2012 Price Level)
Debt Service Ratio 2.0 (in the First year of operation)
Financial Internal Rate of Return 8.9%
Benefit Cost Ratio 1.15 (at 10 % discount rate)
Payback period 12.18 Year
Analysis Period 25 years

Economic Indicators (Based on Avoided Cost)

Economic Internal Rate of Return 21.88%
Benefit Cost Ratio 2.25 (at 10% discount rate)
Net present Value 738.64 Million US$
Pay Back Period 12.18 Years
Specific Energy Cost for Hydro 16.31 US Cent/k Wh (at 10% discount rate)
Specific Energy Cost for Thermal 36.72 US cent/k Wh (at 10 % Discount rate)
Analysis Period 25 years

Economic Indicators (Based on LRMC Cost)

Winter Season Energy Rate 12.72 US Cent per KWh
Summer Seasons Energy Rate 3.82 US Cent per KWh
Emission Benefit 0.598 US Cent per kWh
Benefit Cost Ratio 2.25 (at 10% discount rate)
Net Present Value 76.57 Million US$ ( at 10% discount rate)

Environmental Impact Assessment (Based on Prefeasibility Study)

Relocation of Houses 150
Inundation of Forestland 270ha
Inundation Of Forestland 290ha
Number of People Affected 825
Environmental Cost 11.81 MUS$