The Uttarkashi tunnel rescue mission witnessed some positive outcomes on Tuesday morning as overnight manual drilling went without a hitch, covering over two metres. An auger machine is also being used to push in the pipe to create an escape passage.
The drilling is being carried out by a rat-hole mining expert team of 12 who is currently excavating horizontally through the last 10-or-12-metre stretch of debris of the collapsed tunnel. The workers will go into the escape passage with drills and gas cutters to clear obstacles like iron girders.
Micro tunnelling expert Chris Cooper, who is aiding the operations, told ANI that work is gaining pace. "It went very well last night. We have crossed 50 metres. We have about 5-6 metres to go. We didn't have any obstacles last night. It is looking very positive," he added.
What's Rat-hole mining?
Rat-hole mining is often associated with Meghalaya, where holes are drilled for mining small amounts of coal. This is considered a dangerous practice as it involves digging narrow tunnels, each of which fits only one person to enter and extract coal. The National Green Tribunal (NGT) had banned it in 2014, terming it unscientific.
Worker crawls into a hole which can fit just one and does the digging with tools such as pickaxes, shovels, and baskets.
At the Silkyara tunnel in Uttarkashi, at least 12 experts have been called by Trenchless Engineering Services Private Limited and Navayuga Engineers Private Limited for rat-hole mining from Delhi, Jhansi and other parts of the country.
However, Uttarakhand government's nodal officer Neeraj Khairwal claimed the men brought into the site were not rat-hole miners but people who are experts in the technique. He added that the skilled team will remove the rubble with their hand. "As they remove the muck, the tunnel pipe (800-mm) will be pushed gradually by the machine through the rubble," Khairwal said.
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The workers are divided into teams of two or three. Each team of three men will go into the steel chute laid into the escape passage for brief periods. One will do the drilling, another will collect the muck and the third one will push the muck through the trolley.
They will be in proper gear, wearing oxygen masks and glasses to cover their eyes. They will have to drill at least 10 to 12 metres with their own hands. They will mostly use hand-held drilling machines to remove the rubble and gas cutters for cutting the iron hurdles.
Rajput Rai, a rat-hole drilling expert, said one man will do the drilling, another collects the rubble with his hands and the third places it on a trolley to be pulled out. "We will do the drilling and collect the muck with our hands. We have been doing this for years," another worker Mohan Rai told PTI.
It usually takes around 24 hours for the workers to remove 10-12 metres of muck or rubble but longer if there are rocks in the debris.