Army on Sunday joined the rescue operation in Uttarakhand’s Uttarkashi to save the 41 trapped workers inside the tunnel.

Army has been tasked with the manual drilling, the reports said.

“A unit of Madras Sappers, an engineer group of the Corps of Engineers of the Indian Army, arrived at the site today to assist in the rescue operations,” NDTV reported.

Earlier, after suffering back-to-back setbacks in rescuing the workers stuck inside the tunnel, the authorities decided to work with alternative plans to evacuate the trapped men behind the what was nearly 60-metre-thick wall of rubble.

Also, the auger drilling machine collapsed through the debris at Silkyara-Barkot tunnel.

“Officials are now shifting focus to two alternatives — manual drilling through the remaining 10 or 12 metre stretch of the rubble or drilling down 85-90 metres from the top of the mountain,” HT reported.

National Disaster Management Authority (NDMA) member Lt Gen (retd) Syed Ata Hasnain said, “This operation could take a long time.”

International tunneling advisor Arnold Dix said the workers will be out “by Christmas”, attributing the delays to a “cautious approach” being followed in the operation.

“Manual drilling would involve individual workers entering the already bored 47-metre stretch of the rescue passage, drilling for a brief period in the confined space and then coming out to let some else take over,” the report said.

“Only one person who would have to go inside the narrow pipes can be at the forefront. One can’t work for longer in such narrow passage. Shortage of oxygen and heat generated due to the use of machine is another problem,” HT report quoting an RVNL official said.

The operation as per the report was likely to begin today, after the rescuers take out the blades of the auger machine that have been stuck inside the evacuation pipes that were being pushed through the debris to create a passage for the men trapped since November 12 to crawl out of.

Earlier, the reports said the drilling could not resume after being halted on Thursday afternoon when the platform on which the 25-tonne machine was mounted got destabilised after the drill bit damaged the steel pipes used in the construction of the tunnel. While the machine was disassembled and repaired, officials on Friday said that the evacuation pipe being pushed through the 800mm wide hole being drilled got warped, and the machine was stuck just 10 metres from breaking through.

An official bulletin on the operation said that the evacuation pipes will be pushed further only after “removal of obstruction”.