In an attempt to intensify the rescue operations in Uttarkashi, a rat-hole mining technique will be employed for manual drilling to clear the debris inside the pipe. This comes on the 16th day of ongoing rescue efforts in the Silkyara tunnel.
Uttarkashi: Amidst immense challenges in rescuing the 41 workers trapped inside the Silkyara tunnel, the rescue team is set to employ a rat hole mining technique for manual drilling to remove debris inside the pipe on the 16th day of ongoing rescue efforts. A group of six experts has arrived at the location to perform manual drilling tasks. Their objective is to enter the 800 mm tunnel pipe and manually clear away debris. The team comprises engineers from the Madras Engineering Group of the Indian Army, along with civilian experts. In addition to the drilling machine, the specialists will be equipped with tools such as a hammer, shovel, trowel, and a life support device providing oxygen as they venture inside the tunnel.
Meanwhile, the rescue team was using an auger machine for horizontal drilling that got stuck inside the pipe earlier today. It was then being cut and removed using a plasma cutter. Notably, the heavy machine stuck inside the pipe, produced 48 m of debris on the mouth of the tunnel. The team then removed the debris manually.
Rat Hole Mining
The rat miners are a team of people who are specialists in digging and drilling manually in narrow passages such as tube mines. They mostly work in mines and have the experience of drilling for hours. This technique is normally used in coal mining, especially in regions that have difficult terrain.
“It is a challenging operation. We were called in from Delhi. We reached here yesterday. We are basically from Madhya Pradesh. We will try our best to complete the drilling process as soon as possible,” one of the civilian specialists who reached the site to carry out manual drilling told ANI.
The Indian Army’s engineering unit has built a steel frames. The Madras Sappers will take the frames one by one from the mouth of the tunnel to the inside which will also take at least 10 days. Notably, as many as 30 personnel of the engineer regiment are at the spot and assisting the rescue team.
Over 35 metres of vertical drilling work have been completed so far out of the 86 metres needed to reach the trapped workers.
SJVN, a public sector undertaking company involved in hydroelectric power generation and transmission, started the vertical drilling work on the top of the tunnel atop the hill on Sunday, November 26.
This machine has the capacity to go only to a depth of 45 meters, after which the machine and its parts will be replaced and then the manual drilling work will start.
Today is the second day of vertical drilling and as per National Highways and Infrastructure Development Corporation Limited (NHIDCL), the drilling work is expected to be completed by November 30, as the agencies have set a time frame of 100 hours i.e. four days for it.
Addressing a press conference in Uttarkashi on Sunday, NHIDCL Managing Director Mahmood Ahmad said, “We have to drill around 86 meters to be done within four days that is by November 30. Hopefully, there will be no further hurdles and the work will be completed on time.”
If the 1.2-metre diameter pipe is successfully removed, then the NDRF team will pull up all 41 labourers from the top of the mountain using a harness machine.
Boring is also being done through a 200 mm diameter pipe at a distance of 14 meters from another part which will give a better clarity of the shape and structure of the ground from the surface of the mountain to the surface of the tunnel.
Multiple agencies are working on the rescue efforts. In collaboration with the Border Road Organisation and other agencies, efforts are underway to enter from the other mouth of the tunnel that is the Barkot side. Four blasts were undertaken under the supervision of BRO and so far only 10 metres out of 500 meters have been covered.
Also, the rescuers are planning to build a mini tunnel along the left side of the tunnel, horizontal but perpendicular to the Silkyara tunnel, the work of which will be undertaken by SJVN.
As per the official sources, the length of this perpendicular mini tunnel will be 180 m but it will take another 10 to 15 days. The agency has planned to start the work for this on November 28.
After a portion of the tunnel caved in on November 12, the debris falling in the 60-metre stretch on the Silkyara side of the tunnel trapped 41 labourers inside the under-construction structure.
(With ANI Inputs)