How the Uttarakhand tunnel rescue operation transpired in 17 days. Here's the timeline

After an intense 17-day rescue operation, all 41 workers trapped in the partially collapsed Silkyara Tunnel in Uttarakhand's Uttarkashi district were rescued on Tuesday. The first worker emerged from the trapped area at 7.56 pm, followed by the others brought out soon after

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Reaching the trapped workers within the 2-kilometre-long, 8.5-metre-high tunnel posed significant challenges despite attempts using advanced horizontal drilling techniques through an auger machine. However, when technical issues arose, authorities shifted to manual drilling to clear the final 10 metres of debris.

The rescue team employed vertical drilling alongside manual excavation using the rat-hole mining method, which commenced on Monday. Twelve experts in rat-hole mining were called upon to utilise handheld tools in confined spaces, although this method is contentious and poses risks due to miners working in tight underground passages.

National Disaster Response Force (NDRF) personnel entered a steel chute that had been pushed into the drilled passage over several days, systematically bringing each worker out.

Ahead of the rescue, a specialised ward with 41 oxygen-supported beds had been set up at the community health center in Chinyalisaur, approximately 30 kilometres from Silkyara, to accommodate the rescued workers. Medical staff were on standby, and arrangements were in place to transport workers to more advanced hospitals if required.

Reflecting on the timeline of the rescue operation from the initial entrapment of 41 workers in the collapsed debris at the Silkyara Tunnel in Uttarakhand, let's delve into the process and its progression.

Here's the timeline of what happened from Nov 12

November 12: Following a landslide at the Silkyara-Dandalgaon tunnel on the Brahmkhal-Yamunotri highway in Uttarakhand's Uttarkashi, 41 labourers got trapped. A rescue operation was initiated to free them.

November 13: Uttarakhand chief minister Pushkar Singh Dhami visited the site where workers were trapped and established communication with them using an oxygen supply pipe.

November 14: Efforts involved bringing in 800- and 900-millimetre steel pipes for horizontal digging using an auger machine. However, further rubble caused minor injuries to two workers, hindering progress. Supplies of essential items like food, water, and medicine were ensured for the trapped workers.

November 15: Dissatisfied with the initial drilling machine's performance, the National Handloom Development Corporation Limited (NHIDCL) requested a more advanced auger machine from Delhi, airlifting it to expedite the rescue process.

November 16: The new drilling machine was assembled, and installation began, after which the operation commenced past midnight.

November 17: The drilling machine progressed around 24 metres through the rubble stretch but halted when the fifth pipe encountered an obstacle. Another high-performance auger machine was flown in from Indore to aid the rescue efforts. However, operations ceased when a significant cracking sound emerged from the tunnel in the evening.

November 18: Officials from the Prime Minister's Office (PMO) and experts devised five evacuation plans, exploring alternative methods such as vertical drilling to rescue the workers.

November 19: Drilling activities remained suspended. Union minister of road transport and highways Nitin Gadkari reviewed the rescue operation and emphasised the potential success of horizontal drilling with the auger machine.

November 20: Prime Minister Narendra Modi spoke to chief minister Dhami to assess the Silkyara tunnel rescue operations and highlighted the importance of maintaining morale among rescuers.

November 21: Rescuers released the first video of trapped labourers in the Silkyara tunnel, showing them receiving supplies and communicating through the pipeline. Simultaneously, drilling began at the Balkot-end for an alternative tunnel on the Char Dham route.

November 22: Horizontal drilling progressed to about 45 metres, with around 12 metres of debris remaining. However, iron rods obstructed the auger machine's progress in the evening.

November 23: The obstruction caused by iron rods was removed, allowing for the resumption of rescue operations. Officials reported reaching the 48-meter mark but had to pause due to cracks appearing in the drilling machine's resting platform.

November 24: Drilling at the collapsed tunnel ceased as the auger machine encountered a hurdle, potentially a metal object, after resuming operations.

November 25: International tunneling expert Arnold Dix reported the auger machine used for drilling had malfunctioned, prompting consideration of alternative methods like vertical or manual drilling.

November 26: Rescuers commenced drilling into the hill above the Silkyara-Barkot tunnel, needing to penetrate 86 meters to reach the tunnel. By evening, the equipment had drilled approximately 19.5 meters. Additionally, two BRO officials sustained injuries in a collision near the Silkyara tunnel site.

November 27: A group of 12 rat-hole mining specialists arrived at the site, initiating the manual drilling and excavation process to clear the final 10- to 12-metre stretch of debris.

November 28: Following the manual drilling, rescuers inserted a pipe into the tunnel, reaching the breakthrough point at 57 meters. This enabled the evacuation of the first worker at 7.56 pm on Tuesday, with all the other trapped workers emerging in good health.

(With inputs from agencies)