Minor works like sealing the floodgates and concreting the adit (access) tunnels delayed the commissioning of 720 MW Mangdechhu Hydroelectric Project (MHPA) scheduled for January 10.
One of the four generating units of the 720 MW (MHPA) was supposed to be commissioned on Thursday, January 10. Each unit is capable of producing 180 MW of electricity.
This is the fourth delay in commissioning after it missed the deadline in November last year, a span of three months. Having missed a deadline in October last year, it was pushed to November.
Officials said that a crack was noticed in the one end-arm of the floodgate that was manufactured in Mumbai. The whole component had to be remanufactured, delaying the completion of the dam and pushing the deadline to the New Year. Overall progress by then was 98.99 percent.
Later, on December 13, the project’s managing director, A K Mishra announced the new commissioning date, January 10. The overall physical progress of the work increased to 99.3 percent.
“Everything is done,” A K Mishra said. A small glitch, he said is again unavoidable because the sealing of four floodgates consumed time, more than expected. “We cannot afford to overlook even the slightest fault in the dam, a small error could put the whole project at risk,” he said.
Plugging of one adit tunnel has also slowed down the progress. Adit tunnels are tunnels excavated to access the main tunnel and also function as ventilation. Adit tunnels must be plugged with concrete once the main tunnels are ready to receive water discharge.
Project officials also said that cold winter temperature is making it difficult for the cement to gain rigidity.
Otherwise, the managing director said the debris in the tunnels are cleared and final testing is going on in the powerhouse.
By January 20, plugging of the diversion tunnel would begin at the dam site. Thereafter, AK Mishra said water level in the reservoir would be raised. As the water flows into the desilting chamber and headrace tunnel, officials would monitor the situation to spot seepage. “I am sure there wouldn’t be any,” he said. This was actually supposed to begin by December 20.
Mangdechhu reveals a discharge of 100 cumecs (cubic meters per second) during monsoon. By mid-September, it drops to 58 cumecs, which is more manageable to control the water discharge in a channelised manner.
A K Mishra said the best efforts are on to commission all the four units by end of next month.
The project was initially expected to complete by mid-2017. As per the DPR, MHPA is a seven-year project, meaning that it should have been completed by September 2017.
However, the project lost 15 months in fulfilling formalities and dealing with natural calamities, for instance, flooding in Phuenstholing washed away equipment and roadblocks in Zomkhalum impeded swift transportation. Since MHPA procures cement from Dungsam Cement, the DCCLs temporary halt in production last year also affected the project.
Mangdechhu project is expected to export 3 billion units every year to India. The export tariff was recently finalized at Nu 4.12 a unit.