25 Nov 2023

Uttarakhand Tunnel Rescue: What options are before authorities? How much time will it take?

Efforts to rescue 41 laborers trapped in the Silkyara Tunnel of Uttarkashi in Uttarakhand continue. The American auger machine broke down just 10 meters away from the workers, due to which the rescue work has been halted since Friday.

International tunneling expert Arnold Dix has said that now drilling will not be done with the auger, nor will any other machine be called.

Other options will be used to evacuate the workers. Under Plan B, preparations are being made for vertical drilling from above the tunnel.

Meanwhile, Uttarakhand CM Pushkar Singh Dhami said that a plasma cutter has been ordered from Hyderabad to cut the blades of the auger machine.

After the broken part of the auger machine is removed, manual drilling can start. However, nothing can be said about how much time it will take.

Meanwhile, the Uttarakhand government is supplying hot meals made of rice and lentils through a 6-inch (15-centimeter) pipe to the trapped workers. Besides oxygen is also being supplied through a separate pipe.

Why did horizontal drilling stop?

Since November 21, efforts have been underway to horizontally drill through the Silkyara Tunnel. Progress was substantial, with 47 meters of pipe successfully laid out of the targeted 60-meter section. The drilling, conducted from the Silkyara side, was on the verge of reaching the trapped workers, who were approximately 10-12 meters away. Unfortunately, on Friday evening, the drilling machine's shaft became stuck due to rods obstructing its path.

Despite attempts to apply additional pressure to the machine, it ultimately broke. While some parts have been removed, a significant portion remains lodged. Extraction of the remaining part will necessitate manual drilling, followed by further excavation. Given that only one person can enter the pipe for this task, the process is expected to be time-consuming.

Vertical drilling plan

Currently, drilling operations at the Silkyara Tunnel have come to a standstill, prompting the implementation of Plan B. 

Rescue operations at the Silkyara tunnel will take time, the National Disaster Management Authority (NDMA) said, adding that their focus is now on vertical drilling. According to the NDMA, 86 meters of vertical drilling needed to reach Silkyara tunnel's crust.

Under this plan, a vertical excavation approach will be employed from the hilltop. Materials are being gathered at the hilltop location, and a platform is under construction to facilitate drilling using specialized equipment. This vertical drilling initiative is being spearheaded by Satluj Vidyut Nigam Limited (SVNL), though it comes with inherent risks as there are workers present in the tunnel below.

The procedure involves creating a sizable opening from the hilltop down to the tunnel, posing a potential hazard of debris falling into the tunnel. The duration required for this operation remains uncertain at this point.

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