Geology and pandemic delay Nikachu project

Tenzin Namgay/ Trongsa The 118 Megawatt (MW) Nikachhu Hydropower Project (NHP) in Trongsa is expected to be completed by 2023, two years later than scheduled, due to geological problems and the Covid-19 pandemic. At the onset of the project in April 2016, its completion was slated for 2019 following which the deadline was extended again to June 2022. According to the project engineer (civil and geology) at Nikachhu, NHP requires 12 kilometres of tunnelling between the powerhouse and the dam – worth Nu 300 million – but the excavation was delayed by leaching, and porous and compressible soil. About half a kilometre of tunnelling is still left. Another reason cited for the delay was the unavailability of skilled foreign workers. “As the pandemic hit our country, we lost hundreds of skilled labourers who had worked for decades in the hydropower sector,” the engineer said. “Employing unskilled Bhutanese caused a major delay.” The mandatory 21-day quarantine requirement along with unavailability of quarantine facilities at the entry points was another impeding factor in bringing the skilled labourers into the country. The supply of construction materials and equipment were also stopped with the lockdowns in Phuentsholing and Nganglam. NHP is a run-of-the-river scheme project. A design discharge of 25.45m3/s is diverted through 4 m finished diameter headrace tunnel which is 11,998.50 m long and hits two Pelton turbine in the power house generating an installed capacity of 118 MW. The water is then discharged into the reservoir of Mangdechhu Hydropower Project. Meanwhile, as of July end this year, the overall progress of NHP stood at 71. 43%. Head works (dam, feeder tunnel, desilting chamber and SFT) completed was 75.55 per cent, headrace tunnel 75.41 per cent, power house complex (surge shaft, butterfly valve chamber, pressure shaft, powerhouse, transformer hall, and tailrace tunnel) 64.36 per cent, and hydro-mechanical works 48.12 per cent. The project will provide a mean annual generation of 491.52 GWh from Nikachhu Power House and an additional 323.77 GWh by Mangdechhu Power House on account of Nikachhu water. The project is being funded by Asian Development Bank at debt equity ratio of 65:35 with 48 months as the completion deadline.