Project Location and Accessibility

Druk Bindu I&II hydropower project is a pure run-off the river scheme planned across Druk Bindu. Druk Bindu HPP is located in Tendu Gewog under Samtse Dzongkhag. It is a small hamlet bordered by Lahereni Gewog in the east, Norgaygang Gewog in the northwest, Haa Dzongkhag in the north and Indian State of West Bengal in the southwest. The project site is connected to Samtse town by secondary national highway of 73 km. This route can be used to transport construction materials, equipment, machineries and labour for the project. Samtse is well connected with Indian national highway NH 31C. The weir site is located about 300 m away from the existing Samtse-Tendu road while the powerhouse is below Tendu town.

Field Investigations

Topography survey and mapping was carried out at 1:5000 scale at 5 m contour interval for the whole project area and along the main project components topography survey was carried out at a higher resolution of 1:1000 scale at 1 m contour interval. Geological mapping and geophysics surveys were carried out for ascertaining the geological conditions of the project area. Several stages of field visits were carried out to assess the topographical, geological and environmental & social impact assessment of the project layout.

Project Layout & Features

The project layout for both Druk Bindu I&II has been proposed on the right bank of Druk Bindu.

Druk Bindu-I envisages trench weir type intake at Druk Bindu river with additional diversion of flow from Kachin river through 198 m long, 2 m D-shape transfer tunnel for generation augmentation; Feeder channel of 208 m long (2.80 m x 2.10 m) diverting water from intake to surface desilting chambers; 3,086.40 m long headrace water conductor GRP pipe of 2.30 m Ø conveying design discharge of 9.35 m3/s water from desilting chamber to forebay tank; Forebay tank of 40m x 14m x 8.20m is provided with 3 minutes storage for meeting varying load demand and also absorb surges during transient condition; Steel penstock of 502 m long, 1.60m Ø feeding water to two Pelton turbines in surface powerhouse operating at design head of 219 m; and a tailrace channel of 148 m discharging water back to Druk Bindu at an outfall level of El. 726 m. The updated estimated cost of the project worked out at December 2016 price level was Nu.1,186.72 million excluding transmission line cost of Nu.145 million. The levelized tariff accordingly worked out was Nu. 5.22 per kWh. 

For Druk Bindu-II a design discharge of 9.36 cumecs from the TRC of Druk Bindu I is conveyed to an integration tank, from where the water is conveyed to the surge tube via a 2.3 m dia. 1.4 km long Glass Reinforced Plastic (GRP) pipe. A surge tube of 2.4 m – 3.4 m diameter of 61 m inclined length at the end of the GRP pipe has been provided to accommodate transient in the Water Conducting System (WCS) which is connected to the powerhouse through a 167 m long, 1.6 m dia. steel penstock. A semi underground powerhouse of 30.00 m (L) x 13.00 m (B) x 16.5 m (H) located on the right bank of Druk Bindu accommodates two vertical shaft Pelton turbines generating 2 x 4 MW power, operating at 99 m net head and generating annual design energy of 33.99 GWh.

Project Contract

The construction of Access Roads to Various Project Components of (18+8MW) Druk Bindu HPP” was awarded to M/s Hi-Tech Company Private Limited on October 17, 2023.