The six Indian workers who were buried after the ceiling of the downstream surge chamber will each get a Nu 500,000 life insurance payment and a Nu 50,000 ex-gratia payment by the project.
So far one body was recovered at around 9.15 pm on the night of 3rd January. .
In an accident that occurred around 1.15 am in the early morning of 3rd January a portion of the ceiling of the downstream surge chamber collapsed burying six Indian workers.
They were mainly machine operators working on pumps, boomers and welding. Another ten workers also nearly got buried but they had a narrow escape.
The Punatsangchu Hydroelectric Project Authority Managing Director, R.N Khazanchi said that the cause of the collapse appears to be a shear zone above the ceiling.
Shear zones are weak and unstable areas formed when two rock formation grind against each other. The shear zone is marked by clay like mud, graven and big rocks too forming an unstable mix.
Khazanchi said that the ceiling had been reinforced by steel ribs but it appears that the pressure was too great at tha particular point where the collapse occurred.
He spoke of a similar but less devastating experience with the Tala project in 2001 where again a portion of the downstream surge chamber ceiling had collapsed.
While mourning the loss of what he called six precious lives the MD said that the incident should not affect the overall project completion date of June 2018 which had been brought forward from December 2019 after certain acceleration works had been agreed to.
He said that the work on this particular portion would be delayed as it needed to be studied and rectified.
The MD said that immediately after the mishap the whole thing was assessed a decision was made to call for experts. The experts reached Bhutan yesterday and visited the project site.
Khazanchi said that the first priority was to extract the people from the debris. He said the final plan of action would depend on the investigation by the experts and their plans to deal with the problem.
He pointed out that in terms of critical value the surge chamber would rank in importance after the dam and the Head Race Tunnel.
The surge chamber is to manage the flow of the high pressured river water as it leaves the turbines. The big size of the chamber is to prevent any unexpected flow from taking water back to the turbines.
There were rock falls even 12 hours after the incident. The MD said that two hours after the incident the firefighting, security and disaster teams brought back the power and air ventilation.
The MD explained that the downstream surge chamber is essentially supposed to be a 314 meter long cavern with a total width of 18 meters and height of 58.5 meters.
He said the incident occurred at a length of 130 meters and when the height from the ceiling had reached 33 meters. Around Nu 50 mn worth of equipment has also been lost.