Uttarakhand tunnel collapse: Rat-hole mining experts join rescue ops, manual horizontal drilling begins

Neeraj Mohan

New Delhi, November 27

The daunting task of rescuing 41 workers trapped in the Silkyara-Barkot tunnel in Uttarakhand saw a glimmer of progress today as rescuers successfully started manual horizontal drilling and pipe pushing using the rat-hole mining technique.

A team of six experts persevered with horizontal drilling beyond the impasse at 46.8 metres as the US-made auger machine faced limitations in covering the remaining 10-12 metres of rubble.

Neeraj Khairwal, Secretary of the Uttarakhand Government and nodal officer for the rescue operation, conveyed optimism during an evening press briefing. “There is good progress with the help of experts using the rat-hole mining technique. The process of drilling and pushing the pipe has commenced; around 0.9 metre has been covered in two hours,” he said.

Khairwal explained that the manual horizontal technique involved two essential processes — manually cleaning the muck and pushing the pipe further with a machine. He acknowledged that cleaning the muck could be time-consuming, particularly if they encountered obstacles such as iron bars or girders. “We cannot provide a specific deadline, but we remain optimistic,” he said.

Efforts were also underway to retrieve the broken blades of the auger; around 0.9 metre of progress was achieved after cutting a damaged steel pipe, measuring 1.9 metres. The process might encounter challenges in the next six metres as iron bars and girders could obstruct the way, said Mahmood Ahmed, Managing Director of National Highways and Infrastructure Development Corporation Ltd.

Horizontal drilling had been halted since Friday when the auger blades of the US-made drilling machine broke and became lodged in the pipes intended for creating an escape passage for the trapped workers. The Madras Sappers regiment of the Army’s Corps of Engineers was brought in to clear the lodged blades.

Meanwhile, vertical drilling by Satluj Jal Vidyut Nigam Ltd reached approximately 36 metres with around 50 more metres needed to cover the entire length of 86 metres. Although the vertical drilling encountered some obstacles like stones and rocks, it was deemed to be on the right track, according to Ahmed.

During a media briefing, Lt Gen Syed Ata Hasnain (retd), member, NDMA, said the manual drilling and pushing process would involve Army engineers and pairs of rat miners working in groups of two. “Following repeated obstacles and technical snags, horizontal drilling by the US auger machine seems impossible, and now experts are working on the idea of manual drilling and pushing, with a team of six persons set to work on it,” he said.

Officials said work on another horizontal boring was underway with a concrete bed being created to establish the machine for micro-tunnelling, requiring boring of up to 180 metres. The work was expected to commence in a day or two.

General Hasnain said the authorities were focusing on the physical and mental health of the workers.

A team of doctors has been stationed at the rescue operation site, conducting regular communication with the trapped workers. Video communication has been established and a direct line has been sent to the workers through the life-support pipe for talking to their family members. A camp has been set up for kin outside the tunnel so that they can connect with the trapped workers. The supply of food, medicine and oxygen has been reinforced. There is no requirement for woollens as the temperature inside the tunnel is around 24°C.

36 metres covered vertically, 50 more to go

• Vertical drilling reached approximately 36 metres with nearly 50 more metres left to cover the entire length of 86 metres
• Although some obstacles such as stones and rocks were encountered, the drilling was deemed to be on the right track