Nim Dorji  | Trongsa

The 118MW Nikachu Hydroelectric project marked a significant milestone when it completed excavation of the head-race tunnel from both ends of the first and second phase on January 23.  

The 12-km tunnel is a critical part of the project, HCC’s fifth hydroelectric project in Bhutan.

Guests and officials witnessed the event, also known as tunnel day-lighting moment, in Trongsa. Hindustan Construction Company is executing the works on contracted from Tangsibji Hydro Energy, a 100 per cent subsidiary of Druk Green Power Corporation. 

DGPC managing director Dasho Chhewang Rinzin said that with rigorous planning and constant monitoring the project team was able to achieve the feat despite challenging working conditions. “The excavation works for diversion tunnel at the dam began on August 2, 2016, followed by Adit-III and Adit-II. We have achieved almost twice the overall physical progress compared to last year.” 

The project faced multiple challenges such as poor rock strata, extremely cold conditions and high water-ingress during tunnel excavation. 

Tangsibji Hydro Energy Deputy Managing Director, Sujan Rai said that with the breakthrough in the HRT construction the resource allocation to the other sites of the project has become possible.

He said that the concrete lining of phase two and three of the tunnel will begin immediately.

Rest of the HRT faces breakthrough is planned to be completed by the end of 2020 provided there are no geological surprises.

Of the 12km HRT, only 3.28 km is left for the excavation and the concrete lining of 8km is expected to be completed within 2020. As of January, 49 percent of the project is completed. The work at the powerhouse and dam are also progressing well. 

A press release from the HCC stated that the civil work for the turbine foundation at the powerhouse has now been completed while work at the dam site is on in full swing. The erection of the project’s two turbines is expected to begin this month.

The project is worth Nu 11.96 billion. Of the total cost, 60.8 percent was from Asian Development Bank and 29.68 percent from Commercial Bank of India and 9.52 percent from DGPC.

One of the unique features of the Nikachhu project is that once it is complete the water from the tailrace tunnel will be connected to the Dam of MHPA, which will give additional power generation for MHPA during the lean season.

The project is expected to be operational by 2021. Upon completion, Nikachhu project will export to the Power Trading Corporation of India.