American Auger down in Uttarkashi tunnel, 6 plans to rescue 41 trapped workers

With the number of days of being trapped reaching 16 on Monday, November 27 in the Silkyara-Barkot tunnel (Uttarkashi), the efforts to save the trapped 41 workers, and rescue teams employing multiple strategies have become desperate.

After the American-made auger drilling machine, which was carrying out horizontal drilling broke down on Friday, November 24, the Indian Army has been roped into active assistance and a detailed six rescue plans are being attempted, reported India Today.

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Six synchronised plans

• National Disaster Management Authority (NDMA) member Lt Gen (retd) Syed Ata Hasnain on Sunday, November 26, said, "Six plans are being adopted in a synchronised manner. The operation wasn't put on halt and is still underway in terms of repair work,"
• He also spoke about the best option, reported India Today.

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Vertical drilling

• As the advanced auger drilling machine saw obstacles and subsequent breakdowns during horizontal drilling, rescuers shifted their focus to vertical drilling.
• Lt Gen (retd) Hasnain, highlighted this as the second-best option. "The operation wasn't put on halt and is still underway in terms of repair work," he added.

• India Today reported, the Auger machine, which broke down on Friday, was being worked on.

• The goal is to drill down 86 meters to reach the trapped workers from the top of the hill, with progress expected to reach completion by Thursday, according to National Highways & Infrastructure Development Corporation Limited (NHIDCL) Managing Director Mahmood Ahmed.

Sideways drilling

• Another potential strategy involves sideways drilling, but the necessary machinery had yet to reach the site at the time of the update.
• Lt Gen Hasnain, on Sunday, explained, "Machines for undertaking sideways drilling have not arrived at the collapse site yet and are expected to reach there during the night."

• The delay in arrival was attributed to changes in the vehicle carrying the machine.

Drift Technology

• In case other options falter, drift technology is being considered.

• Lt Gen Hasnain said the need for stability in this process, stating, "We need to keep the pipe stable, remove the broken parts of the Auger, prepare to begin the drift on the side, prepare for top-down drilling, and stabilise and strengthen the 41 brothers trapped inside."

Rescue tunnel

• Simultaneous efforts are underway to create a 483-meter rescue tunnel using blasting techniques from both the Silkyara and Barkot ends, reported Indian Today.
• Five blasts at the Barkot end of the tunnel by the Tehri Hydro Development Corporation (THDC), penetrated some 10-12 meters, said Lt Gen Hasnain.
•  He added that efforts were made to carry out three blasts per day.

ALSO READ: What is taking so long to rescue the 41 trapped workers?

Vertical drilling, Barkot-end

• Yet another approach involves vertical drilling from the Barkot end of the tunnel, a task assigned to the Oil and Natural Gas Corporation (ONGC).
• Lt Gen Hasnain explained, "It will be a 24-inch drilling from the Barkot side, for which a 5-km road is needed and is being constructed by the Border Roads Organisation (BRO)."

The preferred option: horizontal drilling

• Despite setbacks, horizontal drilling, involving the Auger is being deemed the best option.
• Lt Gen Hasnain noted, "Work is on to retrieve broken parts of the Auger machine, which encountered obstacles during horizontal drilling."

• Under this option, "47 meters of drilling have been completed," said Lt Gen Hasnain.

Uttarkashi Tunnel Collapse

• In Uttarakhand's Uttarkashi, an under-construction tunnel, part of the Char Dham Highway Project, collapsed on November 12.
• The accident left 41 workers trapped for over 16 days.
• Since then, rescue teams have been employing diverse strategies, including vertical drilling and creating a rescue tunnel, in a race against time to free the stranded workers.

ALSO READ: Uttarakhand tunnel collapse has rescuers racing against time to save 40 trapped workers