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Daraudi-'A' Hydroelectric Project (6MW)

The feasibility study of the project was carried out by Nil Tara Pvt. Ltd. This PDR is based on review of feasibility study report carried out by Orient Consult Pvt. Ltd. The revised FS report after visited the project site has proposed 1750.0 m headrace tunnel instead of headrace canal in the previous study. Besides, in the revised study, the project layout has been changed except for the alignment of canal and surge shaft. As per the revised concept, the project installed capacity is 6.5 MW and will generate 35.51 GWh of energy annually. According to an estimate only about 40% of population in Nepal mostly in urban areas have access to electricity (CADEC, 2004). The vast majority of rural population has no access to electricity. Besides, Nepal currently faces an acute shortage of power generation capacity, and transmission line network and this situation is expected to remain for several years. There is already peak electricity deficit of more than 100 MW in the INPS. The DKHEP will help to address the deficit to some extent.

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Purpose:

The purpose of this report is to provide up to date description of the whole project, sufficient enough for local financing institution to evaluate the project for financing of the project. This report covers the project hydrology, geology, optimization, project description, project risks, drawings, cost estimate and financial analysis of the project.

Salient Features:

Location

Latitude 28o06’29” N to 28°08’13” N
Longitude 84o39’32” E to 84° 41’ 33” E
VDC Muchok, Takumajh Lakuribot and Saurpani
District Location
Latitude 28o06’29” N to 28°08’13” N
Longitude 84o39’32” E to 84° 41’ 33” E
VDC Muchok, Takumajh Lakuribot and Saurpani
District Gorkha

Drainage Area

Total Area upstream of intake 224 km2
Highest point of the catchment 5379 m
Long-term annual average flow 17.7 m³/s
40% Exceedance flow Design Discharge) 11.32 m³/s (in PPA the discharge value is 11.02 m³/s)
65% Exceedance, 4.53 m³/s
90 % Exceedance flow 3.10  m³/s

Design Floods

1:100 years flood 548 m³/s
Diversion flow (1:5 years dry season flow) 21 m³/s

Flood Level at Dam Site,

Normal supply level El 650.8 m
Minimum operating level El 650.3 m
Maximum flood level El 653.3 m

Cofferdam

Length of First Phase Cofferdam 185 m
Length of Second Phase Cofferdam 130 m
Height above river bed 2.5 m
Shape of Cofferdam Trapezoidal with core material

Undersluice Dam

Type of structure Concrete
Deck level El 653.8 m
Crest elevation El 646.3 m
Foundation level El 643.0 m
Total length of the undersluice weir (Plan) 6 m
Maximum height above foundation to crest 3.30 m
Number of bays 1
Crest length per bay 6 m
Gate type Vertical lift gate
Gate and stop log size 6.0 m x 4.0 m (W x H)

Dam/weir

Type of structure Concrete Weir
Deck level El 653.8 m
Crest elevation El 650.3 m
Foundation level El 643.0 m
Total length of the weir (Plan) 60 m
Maximum height above foundation to crest 7.3 m

Desander Intake/Intake

Intake crest elevation El 648.80 m
Number of bays 4, 2.5 m each
Crest length 10 m
Gate type Vertical lift gate
Gate size 2.50 m x 1.5 m (W x H)
Stop log size 2.50 m x 1.5 m (W x H)

Desander

Type of desander Surface, rectangular type, 2 bay
Design Discharge of Desander 12.45 m3/s
Depth and width of desander 4.5 m and 9.0 m
Length of Desander 75 m
Slope of the desander 2 %
Flushing Gates 4 No, size 2.0m x 1.2 m(W x H)

headrace

Type Rectangular, RCC
Design Discharge 11.32 m3/s
Slope of the Canal 1:1000 and lined
Length 3578 m
Width and height of the canal 2.5 m and 2.5 m, with 0.2 m free board

Canal Siphon at Sota/Jhyalla Khola

Length and Section of siphon 201.16 m, 2.1 m x 2.1 m
Design Discharge 11.32 m3/s

Pipe Siphon at Chainage 1+784 to 1+984

Length and Section of pipe 173 m, 2.2 m diameter, 8 mm thick
Design Discharge 11.32 m3/s
Number of anchor blocks 8

Forebay

Surface Area of Forebay 830 m2
Volume of Forebay 2490 m3
Water level of the Forebay 645.0
Bed level of Forebay 642.0
Spillway length to Syangdi Khola 80 m
Forebay Gate 2.10 m x 2.10 m vertical lift gate

Penstock Pipe

Number 1
Diameter 2.10 m
Length 298.77 + 16 m (bifurcated length)
Maximum shell thickness, Steel 12 mm

Powerhouse

Length x width 28.50 m x 17.0 m
Center line of Turbine El 580.62 m
Bottom Level of Draft Tube El 578.7 m
Number of generating units 2
Turbine type Francis (horizontal axis)
Turbine rated capacity 5.66 m³/s
Generator rated capacity 3.2 x 2 MW
Gross Head from Forebay 645.0 – 579.0 = 66.00 m
Rated net head 63.80 m
Design Discharge 11.32 m3/s
Rated turbine efficiency 91 %
Length of Tailrace Canal 90 m

Tailrace

Type Rectangular, Stone masonry
length
size
64.75 m, canal slope 1:500
3.0 m x 1.7 m

Transmission (33 kV)

Type Outdoor adjacent to powerhouse
Switch Yard 30 m length by 24 m average width
Power will evacuated to Integrated Nepal Power System (single circuit) at Gorkha 33 kV S/S 14.0 km

Access road

Minor improvement of 11 kilo-Chhepetar-Bhaluswara-Barpak road 27 km (approximately)
Road to Dam site 0.5 km

Transformer

Type Three  phase
Rating Voltage Ratio 3.55 MVA x 2 6.3/33 kV
Frequency 50 Hz
Number of units 2

Generator

Rating per unit 3.530 MW (One unit)
Power Factor Voltage 0.85 6.3 kV
Specific speed 227.82
Speed 750 rpm
Number of poles 8
Frequency 50 Hz
Efficiency 94 % (96% in PPA)

Power and Energy

Installed capacity   6.0 MW
Dry season energy    5.423GWh/year (5.247  in PPA)
Wet Season energy    28.833 GWh/year (27.615 in PPA)
Average energy
Note:
   34.256 GWh/year (32.862 (in PPA) PPA
energy estimate includes the outage and transmission  losses

Environmental Study

Downstream release (compensation flow) 0.32 m³/s
Land acquisition by the project 6 ha (approximately)
Number of household to be relocated 3

Construction Period

Construction period from award of civil contract 2 years
Economic Indicators (based on 2012 December price level)
Project cost NRs 96,60,00,000 ( US$ 1,38,00,000)
Cost per kW US$ 2300
Dry season Energy Benefit 8.4NRs/kWh
Wet season  Energy Benefit 4.8 NRs/kWh
Internal rate of return 18.73 %
FIRR 22.62 %
Payback period 10 years
B/C ratio at discount rate of 10% 1.81

 

Location of Projects:

Muchok, Takumajh Lakuribot and Saurpani Village Development Committee Gorkha District in the Western Development Region, Nepal

Downloads:

Project Details of Daraudi-(6MW) with Salient Features.pdf