Super Hewa Khola Hydropower Project is a 6 MW Run of River (ROR) type project located at Hewa Khola, between Chainpur and Panchkhapan Municipality of Sankhuwasabha District, Koshi Pradesh, Nepal. The project is situated near Chinpur, the oldest Newari town. The project corresponds to a design discharge of 2.20 m3/s at Q42.5% including Khawa Khola collection on headworks. The intake/decender structure is located at Oringa, while the flushing gate of headrace is located at Oringa Khola, followed by a gravel basin, headrace, and penstock pipeline spanning at least 3 km that passes through Bansghari, Muchhebung, Thebe gaun, and the powerhouse. The switchyard is located at Muchhebung of Chainpur Municipality on the right bank of the Hewa Khola river. The generated electricity is transferred from the switchyard to the Baneshwor sub-station by a 33 KV single-circuit transmission line, which is 13 km long. The project area belongs to the middle mountain region with a rain-fed catchment on the upper Hewa Basin in Sankhuwasabha.
| Project Location | |
|---|---|
| Province | Province 01 |
| Zone | Koshi |
| District | Sankhuwasabha |
| Intake Site | Bhangtar, just downstream of Hewa-Sewa confluence |
| Powerhouse Site | Agaksu, upstream of Upper Hewa Khola Hydropower Project's headworks |
| Geographical Co-ordinates |
Latitude: 27º 20' 55'' N to 27º 22' 15'' N Longitude: 87º 22' 25'' E to 87º 24' 22'' E |
| Conservation Area (if applicable) | - |
| General | |
| Name of River | Hewa and Khawa Khola |
| Nearest Settlement | Pokhari Bazar/Chainpur |
| Type of Scheme | Run-of-river (RoR) |
| Gross Head | 331.40 m |
| Net rated Head | 320.59 m |
| Installed Capacity | 6000 kW |
| Peak Hour (if P-RoR) | - |
| Average Annual Energy after Outage | 35.72 GWh |
| Dry Season Energy | 11.14 GWh |
| Wet Season Energy | 24.58 GWh |
| Hydrology | |
| Catchment Area |
At intake: 39.76 km2 (Hewa 33.52 km2 + Khawa 6.24
km2 + Oringe 2.89 km2) At powerhouse: 55.8 km2 |
| Average Annual Discharge | 2.76 m3/s |
| Design Discharge (at 42.5% PoE) | 2.20 m3/s |
| Riparian Release | 0.055 m3/s |
| Design Flood Discharge |
Headworks: 68 m3/s Powerhouse: 98 m3/s |
| Average Annual Precipitation | 2343 mm |
| Hewa Collection | |
| Diversion Weir | |
| Type of Weir | Diversion weir with side intake |
| Length of Weir | 18.50 m |
| Crest Elevation | 1506.00 masl |
| Spillway Type | Side spillway |
| Undersluice Opening (W x H) | 2.50 m x 2.50 m |
| Undersluice Invert Level | 1502.10 masl |
| Intake Structure cum Gravel Trap | |
| Type of Intake | Side intake with trashrack |
| Number of Openings | 2 nos. |
| Size of Intake (W x H) | 2.0 m x 0.9 m |
| Intake Sill Level | 1505.00 masl |
| Length of Gravel Trap | 15.0 m |
| Average Width of Gravel Trap | 4.0 m |
| Overall Depth | (2.5 - 3.9) m |
| Particle Size to be Trapped | Up to 20 mm |
| Flushing Channel | 1.0 m x 1.0 m |
| Desanding Basin | |
| Type | Dufour double chamber type |
| Dimension (L x B x H) | 50.0 m x 5.0 m x (4.3 - 5.2) m |
| Inlet Transition Length | 10 m |
| Particle Size to be Settled | 0.20 mm |
| Trapping Efficiency | 95% |
| Khawa Collection | |
| Typology |
Diversion Weir: Temporary type weir by gabion structure Intake: Drop intake (0.50 m x 0.50 m) Gravel Trap: RCC Gravel trap Collection Pipe: 1490 m long buried 0.50 m dia. HDPE pipe |
| Oringe Collection | |
| Typology |
Diversion Weir: Temporary type weir by gabion structure Intake: Drop intake (0.50 m x 0.50 m) Gravel Trap: RCC Gravel trap Collection Pipe: 332 m long buried 0.28 m dia. HDPE pipe |
| Headrace Pipe | |
| Type | Mild steel welded pipe |
| Internal Diameter | 1.35 - 1.15 m |
| Length | 3146.55 m |
| Steel Thickness / Type of Lining | 7 - 20 mm |
| Number of Anchor Blocks | 64 nos. |
| Surge Tank / Forebay | |
| Type | Surge pipe |
| Connection Pipe Length | 78.60 m |
| Total Length | 83.55 m |
| Up Surge Level | 1515.20 masl |
| Down Surge Level | 1494.90 masl |
| Steel Penstock Pipe | |
| Type | Mild steel welded pipe |
| Internal Diameter | 1.05 m and 0.74 m |
| Length | 674.35 m with branch pipe |
| Steel Thickness | 7 - 20 mm |
| Number of Anchor Blocks | 10 nos. |
| Number of Saddle Supports | 46 nos. |
| Powerhouse | |
| Type | Surface with indoor switchyard |
| Size (L x W) | 28.50 m x 17.50 m |
| Height | 18.9 from floor level |
| Turbine Axis Level | 1174.50 masl |
| Tailrace |
Type: Rectangular RCC closed Tailrace Length: 49.0 m Size (W x D): (1.4 - 2.0) m x 2.0 m Tailrace Water Level: 1172.20 masl |
| Turbine |
Type: Horizontal axis Pelton Number: 2 nos. Rated Output per Unit: 3125 kW Turbine Axis Level: 1174.50 masl Net Head: 320.59 m Discharge per Unit: 1.10 m3/s Efficiency: 90% |
| Governor |
Type: Electronic PID Control Adjustment for Speed Drop: Between 0-5% |
| Generator |
Type: 3-phase AC synchronous Rated Output per Unit: 3530 kVA Power Factor: 0.85 Generation Voltage: 6.6 kV Frequency: 50 Hz Number of Units: 2 nos. Excitation System: Brushless excitation Efficiency: 96% |
| Transformer |
Type: Outdoor step-up power transformer Rated Capacity: 7200 kVA Voltage Levels: 33/6.6 kV (Primary/Secondary) Number of Units: 1 nos. Vector Group: YNd11 Frequency: 50 Hz Efficiency: 99% |
| Transmission Line | |
| Voltage Level | 33 kV |
| Length | 13.50 Km |
| Conductor Type | ACSR DOG, 100 mm2 |
| From | Power plant switchyard |
| To | 33/220 kV Baneshwar substation (33 kV busbar) |
The project site is accessible from Kathmandu via Kathmandu-Bardibas-Itahari-Chainpur road with a total distance of approximately 525 km. The project access road length is about 9 km from Chainpur to the headworks site, which starts from Pokhari Bazar on Chainpur-Nundhaki Highway. Another road also starts from the powerhouse via the lower project headworks.
