Salient features of the Project
The Project components are located in the Mangan District of the state of Sikkim with Dam at the Chugthang Village and the Power House site at Singhik. The project utilizes the fall of head in the River course, of about 800 meters between these two villages.
The main components of the project are:-
- 60 M high Concrete Faced Rockfill Dam (CFRD) with a Plastic Concrete Cut off Wall, 400 M downstream of the confluence of rivers Lachen Chu and Lachung Chu near village Chungthang.
- 2 Tunnel Spillways of 10m Diameter (horse shoe shape)and one high level surface spillway on Left bank
- 1 Reservoir Flushing Tunnel of 11m Diameter (horse shoe shape)which acts as an Auxiliary Spillway also on the Right Bank.
- 2 Nos. Desilting Chambers of size 320m x 17m x 23m (L x B x H) to separate silt particles of more than 0.2 mm size.
- 13.8 KM long Head Race Tunnel of 7.5 M diameter (horse-shoe shape) with design discharge of 175 cumecs.
- 158 M high Surge Shaft of 13 M diameter.
- 2 Nos. 1.4km M long Pressure Shafts of 4.0 M diameter each of which has 659 m Vertical portion, 468 m inclined portion and 304m horizontal portion.
- Underground Power House of 21 M x 44 M x 214 M for housing 6 units of 200 MW each having vertical Pelton turbines.
- 1327 M long D-shaped Tail Race Tunnel of 8.2 M x 8.0 M size.
Unique Features of the Project:-
- Best and most unique HE Project with high head of 800 m against short HRT length of 13.8 km.
- Best studied and investigated project in the country by agencies like CWC/CEA, GSI, NHPC and SUL.
- Most dependable hydrology with data of over 30 years period for arriving at the dependable flow.
- Environment friendly project – Major project components underground, minimum impact on environment.
- Despite the size of the project no Resettlement and Rehabilitation issues leading to no local/ R & R issues.
- Sikkim is politically most stable, peaceful and investor friendly state.
- Local people are pro-development leading to smooth implementation of the project.
The first three generating units i.e. Unit 2, 3 and 4 were commissioned on 23 February 2017. The balance three generating units i.e. Unit 1, 5 and 6 were commissioned on 28 February 2017.