Dechen Dolkar 

With 87.75 percent of the project completed, the 118MW Nikachhu Hydropower Project in Trongsa is expected to commission by December this year.

The project has completed 89 percent of the headworks components which include the dam, power intake structure, main feeder tunnel, and desilting chamber complex works.

Similarly, the progress of the Head Race Tunnel (HRT) construction stands at 88.54 percent, 88.84 percent for the powerhouse complex, 66.20 percent for hydro-mechanical and 90.52 percent for the electromechanical works.

The construction of transmission lines (132kV Double Circuit Line of 18.6km) is almost complete (99.8 percent).

Project management officials said that the most critical component in the completion of the project is HRT Face 6 and Face 7.

“After going through various challenges on adverse geological conditions with heavy ingress of water, the excavation breakthrough between Face 6 and Face 7 happened on December 14, last year,” an official said.

However, the management said that the uncertainties associated with excavation have now been eliminated with the breakthrough between Face 6 and Face 7 of HRT.

The project management also said that because of the very poor geology,  the project also faced challenges in the dam excavation where they “literally had to change the methodology of excavation”.

The management said that the adversity of harsh weather conditions also hampered the work progress, where foreign workers enrolled with the contractor left the site to avoid cold weather.

The project also faced challenges for the pressure shaft excavation where they encountered extremely poor geology or shear zone both in upper and lower limb pilot hole excavation.

“Despite the restriction and supply of raw materials being interrupted during the Covid-19 pandemic, the contractor was forthcoming and put in extra effort to ensure that works at critical fronts were not interrupted,” the official said.

The project missed two deadlines so far. Of the initial estimated cost of Nu 11.89B, around Nu 12B has been spent. “The cost of the project is likely to increase to Nu 13B,” the project official said.

The tariff as per Power Purchase Agreement with Power Trading Company India Ltd is Nu 3.30/kWh.