Indian rescuers are carrying out manual digging to evacuate 41 workers who have been trapped inside a collapsed tunnel in the Himalayan Uttarakhand state for two weeks after a drilling machine became stuck in debris.
Authorities were using a US-made auger machine with attached rotating blades that cut through rock and debris to penetrate nearly 60 metres of rubble at the collapsed Silkyara tunnel in Uttarkashi district and insert the 90 centimetre wide pipes to create a ‘tunnel’ to pull out the workers.
The hopes of extracting the workers who include plumbers, electricians and other machine operators were dashed on the weekend when the machine that successfully drilled through the rubble up to 47m broke down after it got entangled in a steel and iron girder, halting the rescue work temporarily.
The pieces of the auger machine were removed bit by bit and manual digging started on Monday to make an escape route for the trapped workers, Colonel Deepak Patil, General Manager of National Highways and Infrastructure Development Corporation Limited, one of around a dozen rescue agencies, said.
“Earlier we were primarily focusing on the debris itself where we were trying to insert 900m pipes. The pipe got inside about 47m but got stuck, entangled in the debris of steel and pipe reinforcements. We got the auger to penetrate but it also got broken and we had to cut it piece by piece,” Col Patil told The National.
“This morning we could remove all the pieces of augers by using gas cutters. We will be going into the pipe and will be doing manual digging and pushing hydraulic jacks. We will not use the auger any more,” he said.
The rescuers faced another obstacle when one of the pipes inserted to bring out the workers got bent. The authorities are inserting pipes one after the other to make a “tunnel” inside the Himalayan roadway tunnel that will be used by the workers to crawl out.
The rescue workers are just 9-10m away from those trapped and six “rat miners”, skilled workers who will get into the pipes and remove the debris with their hands, have been sent in. Although time-consuming, it is seen as the most feasible option.
Critics say that the augur machine's deployment on the floor of the tunnel was a faulty decision as experts had ignored the fact that the concrete debris includes steel bars and girders.
But Mr Patil said that the methodology was proven, however, the hurry to rescue the workers led to damage to the machine.
“It is not a single man operation; it is a multiple-agency operation and to use the auger machine was a collective decision … the debris has lot of steel lying in it, we knew that it was there and knew the longitudinal location but did not know horizontally where it lay,” he said.
“The extent of the collapse and the debris cannot be assessed unless there is a ground radar which is powerful and has well-defined output…It was a confirmed methodology, but we were in a hurry to bring them out.”
The agencies are also vertically drilling to create an alternate escape route. They need to drill down 86 metres to insert 1.2 metre diameter pipes vertically to reach the workers.
The work began on Sunday and drilling up to 31 metres has been completed.
There were risks associated with vertical drilling given the fragile mountain.
“Vertical drilling was always an option, but time consuming as we had to make a road to reach the top of the hill.”
“We started it and could get good success in that, however, there was a little risk as it could have damaged the tunnel much more from the ground areas because we did not know the geology there, so we were keeping that option on side,” Mr Patil said.
