New Delhi: As horizontal drilling work at the collapsed Silkyara tunnel site remained halted for more than 48 hours, rescuers began vertical drilling on war footing to evacuate 41 workers trapped inside for more than 14 days.
Officials said it will take four days to reach workers through the vertical escape passage, as the work to retrieve parts of the broken auger machine from under the debris will continue till Monday morning.
Briefing the media in the national capital, NDMA member Lt. Gen. Syed Ata Hasnain (Retd) said that as many as six plans, including vertical and manual digging, are being executed to rescue the trapped workers, but the best option so far is horizontal drilling, under which 47 metres of drilling have been completed.
On Sunday, officials overseeing the rescue operation at the incident site said that, as planned earlier, Satluj Jal Vidyut Nigam Limited (SJVNL) has started vertical drilling to create a 1.2-metre-diamter escape passage.
According to officials, nearly 86 metres of escape passage will be required from the chainage distance of 305 metres to reach the workers from the top of the tunnel. Vertical drilling of 19.2 metres was done on Sunday.
"We hope SJVNL will be able to drill through 86 metres to open the tunnel in the next four days, as we have kept the 100-hour deadline for it," additional secretary ministry of road transport and highways (MoRTH) Mahmood Ahmed said.
Mr Ahmed said although drilling will take around 70 hours, the four-day deadline for escape passage from the top of the tunnel includes the time needed to switch from the present machine to another.
"Two machines will be required for drilling 86 metres of passage of 1.2 metres in diameter, as one machine can drill only 40 metres," said Mr Ahmed.
Meanwhile, work on the horizontal escape passage remained hampered for more than 48 hours after it was stopped on Friday evening. Rescue work officials said experts and technicians were still trying to take out the broken shaft and broken blades of the auger machine stuck inside the collapsed tunnel rubble.
"Around 13 metres of the stuck shaft still remain inside the debris. All efforts are being made to clear it by Monday morning. Plasma cutters, laser cutters and glass cutters are being used to cut and remove stuck parts of the machine from the debris," said Uttarakhand government nodal officer deployed for rescue operations Neeraj Khairwal.
Mr Khairwal said that a laser cutting machine was flown from DRDO Hyderabad, while a plasma cutter was brought from Chandigarh on Saturday night.
Besides, a team of ONGC experts from Rajahmundry was also flown down to the tunnel sites to expedite the disposal of trapped auger machine parts. A unit of Madras Sappers, an engineer group of the Corps of Engineers of the Indian Army, arrived at the site on Sunday to assist in the rescue operations.
"We are getting the desired result as new equipment has 40 per cent more efficiency. It's tough and challenging as metal cutting work is being done inside the 800-mm-diameter steel pipeline with equipment like plasma, laser and gas cutters that generate a lot of heat and temperature," said Mr Khairwal.
