Some 400 employees and workers at Mangdechhu Hydropower Project have cleaned the 13.5km tunnel for water discharge.

The project’s managing director, A.K Mishra, said all the rubbles and iron pieces, basically waste left inside the tunnel, were cleared. He said next cleaning would be done on December 9.

“We want to ensure that no stone and iron pieces enter the generating units,” he said.

Adit tunnels are being plugged with concrete. Adit is also tunnel excavated to access the central point from where the hydro tunnels like headrace and tailrace tunnels are constructed. An adit will have to be disconnected from the main tunnel or plugged in after completion of the main tunnels.

To expedite this process, A.K Mishra said a latest drilling machine capable of drilling deeper holes meant for curtain grouting, which would facilitate the concrete plugs, was being deployed.

“This is specific machine has been mobilised on the request of MHPA by the GECPL {an Indian construction firm),” he said.

He said majority of work was completed except for the installation of floodgate in the dam. Concreting of dam was done before the schedule. However, when it came to hydro-mechanical works, a crack was found in one end-arm of the gate upon reaching the site. The manufacturer in India had to re-manufacture the equipment and it took a month.

“Other wise, we could have done the testing and commissioning by end of this month,” the managing director said.

However, by December 18, all hydro-mechanical work would be completed

In the powerhouse, two generating units are completed and ready for commissioning. One unit, he said, would spin on December end and, a month later, another would start generating electricity. In February, two more units would start producing electricity.

Tshering Dorji