20 metres dug as rescuers switch to vertical boring; Army tries to clear horizontal path too

Neeraj Mohan

New Delhi, November 26

With the US-made auger machine failing to meet its objective after facing technical snags and stalling at 46.8 metres during horizontal drilling, the rescuers have switched to vertical drilling from hilltop, frustrating efforts to retrieve the 41 workers trapped in the Silkyara-Barkot tunnel since November 12.

Need to drill 86 metres to reach trapped men

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• 86-metre vertical drilling needed to reach workers; first machine to be replaced at 40m, it may take 100 hrs
• Gear arrives to remove broken machine parts in horizontal pipe; Army to drill remaining 12m manually
• In addition, ONGC is engaged in 24-inch diameter vertical drilling towards Barkot end of tunnel
• Perpendicular (sideways) drilling yet to start due to delayed equipment arrival; drilling will span 170m

The Satluj Jal Vidyut Nigam’s drilling machine commenced vertical drilling on Sunday, successfully penetrating a stretch of 20 metres by night. To reach the trapped workers, a total of 86 metres of drilling is required. The first machine, capable of drilling up to 40 metres, will be replaced, a process expected to take a total of 100 hours, the officials say.

Lt General Syed Ata Hasnain, member of the National Disaster Management Authority (NDMA), explained in a press briefing vertical drilling was somewhat less complex than horizontal drilling. However, challenges such as potential geological obstructions, including aquifers, could not be ruled out. But a study for vertical drilling had shown good signs, he added.

In addition to the 86-metre vertical drilling challenge, rescuers must break through the tunnel crust to access the workers. Evacuation would be facilitated using a bucket, led by National Disaster Response Force (NDRF) experts. The backup plan for perpendicular (sideways) drilling has not yet commenced due to delayed equipment arrival. This drilling will span 170 metres.

Simultaneously, the Oil and Natural Gas Corporation (ONGC) is engaged in 24-inch diameter vertical drilling towards the Barkot end of the tunnel, conducting a blast covering a distance of 483 metres from that side.

Meanwhile, the horizontal drilling under Plan A is ongoing, with experts working on removing broken auger machine parts obstructing the path. The remaining 10-12 metres will be drilled manually. A plasma cutter machine from Hyderabad will aid removal of broken augers, while the Indian Army’s engineer regiment has been summoned for manual drilling.

Union Minister General VK Singh (retd) arrived at the Silkyara tunnel site to oversee the ongoing rescue operation. Officials are considering sending a cricket bat and ball to the workers, providing an outlet for recreation within the tunnel chamber.