Sanjen Hydroelectric Project (SHEP)
Sanjen Hydroelectric Project (SHEP)
PROJECT DESCRIPTION
Sanjen Hydroelectric Project (SHEP):
Sanjen Hydroelectric Project utilizes the tail water from the Sanjen (Upper) Hydroelectric Project and therefore is a cascade run-of-river scheme. The whole scheme is divided into three work sites, viz.Headworks Site that covers Chhupchhung feeder system, spillway, intake/forabay and pressure conduit, Underground Works that covers headrace tunnel, rocktrap, surge tank, penstock shaft (inclined and horizontal) and construction adits, and Powerhouse Site that covers powerhouse structure, tailrace and switchyard.
The headworks site is located at Simbu Village of Chilime VDC. The headworks consist of overflow spillway, intake/forebay of size 80m long and 30m wide, a 115m long low pressure conduit leading to headrace tunnel portal and complete Chhupchhung intake and feeder system.
Headrace tunnel is 3630m long, inverted D shape of excavated section 3.5m x 3.75m and is partly unlined, partly shotcrete lined and partly concrete lined. Surge tank is restricted-orifice type of height 55 m and diameter 5.5 m. Penstock shaft (inclined and horizontal) is 1030m long and underground. Surface powerhouse is located at Chilime Village of Chilime VDC. Powerhouse will accommodate three units of vertical axis Pelton turbines of capacity 15 MW each and three units of 3-phase synchronous AC generators of capacity 16.85 MVA each. Three numbers of tailrace pits joined at tailrace manifold will discharge the tail water to the approach canal of existing Chilime Hydropower Plant. Excess water will be discharged into Chilime River. Surface switchyard is located adjacent to the powerhouse complex.
HYDROLOGY
The tailwater from SUHEP feeds directly into the intake of the downstream Sanjen Hydroelectric Project (SHEP), a cascade run-of-river system. Additionally, SHEP utilizes 0.5 m³/s from the Chhupchhung Khola. The catchment area at the Chhupchhung Khola weir site is 24 km². Annual precipitation in this area is 1,200 mm, with monsoon precipitation accounting for 1,000 mm. Long-term mean monthly flow data at the Chhupchhung weir site reveal a maximum of 3.58 m³/s in August and a minimum of 0.28 m³/s in April. The 100-year design flood for this tributary is estimated at 71 m³/s. Incorporating this additional flow, SHEP’s design discharge is finalized at 11.57 m³/s.
GEOLOGY
The project area is situated in the Higher Himalaya and the Lesser Himalaya, Central Nepal.
Chhupchhung weir lies in recent alluvial. Forebay/Intake of SHEP is in a gently sloping terrain consisting of about 25-30m thick deposits with angular gravel to boulder sized rock fragments of schist, quartzite and slate in loose soil sediments.
Common rocks along the headrace tunnel alignment are fair to good. Surface mapping reveals thin colluvial masses i.e. less than 1 m thick on downhill slope in surge tank area and rock cliff on its uphill section.Rock mass along the penstock is of mixed lithology. Thickness of the quartzite bands range from 5 to 20 m.The powerhouse site is proposed in a flat alluvial terrace. The switchyard is proposed in terrace deposits characterized by unconsolidated alluvium deposits.
Status of the Project
Sanjen Hydropower Project’s commercial operation started from December 16, 2024 and the power generated from it is being transmitted via Chilime-Trishuli 220 kV transmission line.
SALIENT FEATURES
| Location | Chilime V.D.C. of Rasuwa district. |
| Type of Project | Cascade Run-of-river |
| Hydrology | 202 km2 |
| Catchment area (Dam site) | 2.4 m3/s |
| 90% dependable flow | 11.57 m3/s(including Chhupchhung flow) |
| Design flow | (Q40) |
| Design flow from Chhupchhung | 0.50 m3/s |
| Geology | |
| Rock Type | Medium grade metamorphosed schist and quartzite |
| Head | |
| Gross | 442.0 m |
| Net | 433 m |
| Headworks | |
| Intake Type | Off take from Tail Water of Upper Power Plant |
| Head Pond (Forebay) | 10 min. |
| Headrace Tunnel | |
| Length | 3630 m |
| Section | 3.5 m (w) x 3.75 m (h): D- shaped |
| Surge Tank | Restricted Orifice Type |
| Type | |
| Size | 51.0 m (h), 5.5 ~5.8 m (dia) |
| Size of Orifice | 1.24 m (dia). |
| Penstock | |
| Size | 1020 m (l), 1.06 ~ 2.5 m (dia) |
| Powerhouse | |
| Type | Surface |
| Size | 55.3 m (l) x 13 m (b), 25.8 m (h) |
| Tailrace | 14 m (l) x 5.5 m (b) x 2.7 m (h) |
| Turbine | |
| Type | Pelton, Vertical Axis |
| Capacity | 3 Nos., 15 MW each |
| Generator | |
| Type | 3 Phase Synchronous AC |
| Rated Power | 3 Nos., 16.85 MVA each |
| Installed Capacity | 42.5 MW |
| Transmission Line | |
| Length | 1.5 km |
| Voltage | 132 kV |
| Annual Energy Generation | 251.94 GWh |
| Dry Months Energy | 35.71GWh |
| Wet Months Energy | 216.23 GWh |
| Salable Energy | 241.86 GWh |
| Dry Month Energy | 34.28 GWh |
| Wet Month Energy | 207.59 GWh |
| Project Cost | |
| Total Project Cost (2011 Dec) | NRs. 5024.29 million |
PROJECT LAYOUT MAP
