Solu Khola (Dudhkoshi) Hydro-electric Project – 86MW

Solu Khola (Dudhkoshi) Hydro Electric Project (SKDKHEP) is an 86 MW Run Of River (RoR) type of project located at Dudhkaushika & Necha-Salyan Rural Municipilaties (Former Tingla, Kangel & Panchan V.D.Cs) of Solukhumbu district, Sagarmatha zone of Eastern Nepal. The project area is about 130 km (aerial) easto of Kathmandu and is situated within longitude 86°37’35” to 86°41’15” East and latitude 27°21’53” to 27°25’15” North. The project utilizes a design discharge of 17.05m³/s from Solu Khola and the elevation difference between the proposed intake at Solu Khola and powerhouse at Dudhkoshi River for power generation.

The proposed headworks is located at Gairigaun village of Necha-Salyan Rural Municipality, about 600 m downstream of the suspension bridge over Solu Khola River at Sanghutar. Surface settling basin, headrace tunnel, inclined pressure shaft passes along different places of Dudhkaushika Rural Municipilaties. The proposed powerhouse, switchyard and tailrace canal all are located near Maikubesi of Dudhkaushika Rural Municipilaty, on the right bank of Dudh Koshi River, about 1 km upstream of the suspension bridge over Dudh Koshi River at Jaleshwor Mahadev.and 3.5km upstream of the confluence of Solu Khola and Dudh Koshi River.

The project consists of a simple weir with undersluice, side intake, gravel trap, approach channel, an desalting basin, headrace tunnel, surge shaft, inclined pressure shaft and horizontal penstock tunnel, surface powerhouse and a tailrace canal.

Salient Features:

 

S.N. Components Description
1 Project Location Solukhumbu District, Sagarmatha Zone
Intake Site Necha-Salyan Rural Municipality
Powerhouse Area Dudhkaushika Rural Municipality
Latitude 27°21’53”N to 27°25’15”N
Longitude 86°37’35”E to 86°41’15”E
2 General
Name of River Solu Khola
Type of Scheme Run-of-River
Gross Head 613.20 m
Net Head 598.09 m
Installed Capacity 86,000 kW
3 Hydrology
Catchment Area 454 km2
Design Discharge 17.05 m3/s
Design Flood Discharge 475 m3/s (100 Yr. Flood)
4 Diversion Weir
Type of Weir Gravity free flow concrete
Length of Weir 31.8 m
Max. Height of Weir 7.4 m from foundation level
Crest Elevation EL. 1,260.5 masl
5 Intake Structure
Type 4 no.s of Side intake
Size (W x H) 2.80 m (W) x 2.30 m (H)
Crest elevation of Intake EL. 1,257.6 masl
6 Undersluice Structure
Type 2 sets of Radial Gate
Size (W x H) 2.00 m (W) x 3.00 m (H)
Crest elevation of Undersluice EL. 1,254.6 masl
7 Gravel Trap
Type Rectangular, RCC
Size 6.15m (W) x 6.6 m (L)
Bed load size to trap 5 mm
8 Approach Canal
Type and Number Free flow box culvert, total 4 nos
Size 2.2 m x 2.2 m
9 Desanding Basin
Type Surface
No of Bays 4 Nos
Dimension (L x B x H) m 85 m (L) x 9.5 m (W) x 4.5 m (H) Effective
Particle Size to be Settled 0.15 mm (90% trapping efficiency)
Outlet Water Level EL. 1,260.35 m
10 Headrace box Culvert
Length 50.0 m
Size 4.5m (W) x 4.5m (H)
Numbers 1 (One)
11 Headrace Tunnel
Section Type Inverted-D
Length 4,259.0 m
Size 4.0m (W) x 4.25m (H)
Support Shotcrete
12 Surge Tunnel
Size 4.0m x 4.0m of 372.0m length in slope
13 Penstock
Length upto Trifurcation 2098.0 m
Horizontal section before Drop Shaft 1 20.0 m
Drop Shaft-1 226.0 m
Inclined Section 1 717.0 m
Drop Shaft-2 201.0 m
Inclined Section 2 934.0 m
Internal Diameter and length 2.35 m for 1st 1130 m length,

2.25m for next 551m length and

2.1m for 417 m length (last portion)

Thickness of steel penstock 10 mm ~ 44 mm with yield strength 450MPA
14 Powerhouse
Type Surface
Size 54.6 m x 16.2 m x19.45m
15 Tailrace
Type Free Flow, Box Culvert
Length 70 m
Size (B x H) 4.6 m x 1.9 m
16 Turbine
Type Vertical Axis Pelton
Speed of Turbine 600 RPM
Rated Output Capacity per Unit 3 x 30.32 MW with 10% COL
Efficiency 91%
17 Governor
Type Digital/Hydraulic with PID Control
Adjustment for Speed Drop Between 0 to 5 %
18 Generator
Type Synchronous 3 Phase
Rated Output Capacity per Unit 34.6 MVA
Voltage 11 kV
Efficiency 97%
19 Transformer
Type Out Door, Oil Immersed
Rated Capacity per Unit Three Phase 35 MVA total Nos 3
Frequency 50 Hz
20 Transmission Line
Length 10.5 km
Voltage 132 KV
Interconnection Point Proposed NEA sub-station at Lammane, Necha-Salyan.
21 Power and Energy Generation
Mean annual energy per year 520.20 GWh (Dry- 100.27 GWh, Wet- 419.93 GWh)

 

Project Progress and Present Status:

  • Survey License obtained.
  • Feasibility study completed.
  • Connection agreement signed with NEA.
  • Generation License obtained.
  • PPA signed with NEA.
  • Syndicated Credit Facilities signed with NIBL as lead bank along with 10 other banks and investment company as consortium members.
  • Transmission Line Survey License obtained.
  • Hydro Venture Pvt. Ltd. acquired.
  • Generation License transferred to Sahas Urja Ltd.
  • EPC Contract of Civil, HM and EM signed with CMC di Ravenna.
  • Detailed Engineering Design being carried out by Hydro Consult Engineering Ltd.
  • Physical Model Tests going on in Hydro Lab.
  • IEE for Transmission Line being carried out.
  • Camp construction completed on headworks and powerhouse.
  • Bailey bridge installed at intake site.
  • Access road to headworks and powerhouse completed.
  • Land Acquisition ongoing.

 Strengths of the project:

  • Smaller intake and waterway structures.
  • Shorter tunnel length.
  • Higher percentage of dry energy compared to other projects in Nepal.
  • Connection agreement signed for a nearby substation (<14 km)
  • Minimum length of access road to be constructed (<15 km)
  • Minimum socio-environmental impacts
  • Satisfactory social support to the Project.
  • Dedicated Transmission line in Double Circuit 132 KV transmission line to Lammane Substation, Necha-Salyan.
  • All expenses will be borne by NEA for construction of Substation.
  • Stable rock and good land area for penstock alignment.
  • Hydrology is very reliable and is justified with various hydrological data.
  • High head with low design discharge.
  • Flow of semi snowed river- dry season discharge is maintained

 

Project Gallery

Accessibility:
  • Roadway
    1. Kathmandu to Banepa - 27.2 Km, Araniko Highway
    2. Banepa to Khurkot – 115.3 Km BP Highway
    3. Khurkot to Ghurmi – 65.5 Km Madhya Pahadi Highway
    4. Ghurmi to Okhaldhunga –41.7 km Harkapur Okhaldhunga Road
    5. Okhaldhunga to Ramitey-31 Km, Black Topped Road.
    6. Ramitey to Intake- 7.3 Km, Track Road
    7. Intake to Powerhouse- Under Construction

    Airway
    Tribhuvan International Airport to Phaplu Airport, 30 minutes
    Phaplu Airport to Headwork via roadways, 18 Km, 30 minutes