Disaster Strikes on Diwali
On 12 November 2023, at 0530AM , a collapse occurred inside the Silkyara tunnel during reprofiling work. 41 workers have been trapped at a location of 205 to 260 meter from the portal. The trapped area measures 8.5 meter in height and spans upto 2 km.
Silkyara Project Overview:
In February 2018 , the union cabinet granted approval for the construction of a 4.531km two lane bi-directional tunnel known as the Silkyara Bend- Barkot Tunnel. It is situated along NH-134 (Old NH 94) in Uttarakhand. This project is part of the Chardham Mahamarg Pariyojana. It will reduce the travel distance from Dharasu to Yamunotri by about 20 km and travel time by about an hour .Its estimated construction period is of 4 Years and a cost projection of Rs 1119.69 crore. The total project cost is estimated of Rs 1383.78 crore including land acquisition and rehabilitation. It was expected to complete by 14 May 2024.
The project will be implemented by the Ministry of Road Transport & Highways (MoRTH), through National Highways & Infrastructure Development Corporation Ltd. (NHIDCL), a wholly state owned company, formed in 2014 for development of highways in states on the international borders.
Rescue on Motion
The rescue operation of the trapped workers begin on the war footing involving multiple agencies to include the Uttarakhand Administration, SDRF, NDRF, MoRTH, NHIDCL, NHAI and BRO facilitating in fresh air, oxygen, water electricity and small packed food through pipes.
International expert Arnold Dix from the International Tunneling and underground Space Association Geneva, Chris Cooper from Australia expert in Micro tunnelling.
Rescue Strategies Unveiled: Five Plans to Save Lives
The Core team has worked out on Five Options to rescue the trapped workers. The Plans are –
Option-1
Horizontal boring from Silkyara end using American machine- As conveyed by agencies one option is , horizontal boring by NHIDCL from the Silkyara end (where the debris is), using an American boring machine
Option-2
1.2 m wide hole being dug vertically, from above – Another option is to dig 1.2 metre wide hole vertically, from above the tunnel. This will need around 90 metres of digging, and will meet the tunnel at the 320-metre mark from the Silkyara side
Option-3
Horizontal micro-drilling from the left, to make escape tunnel – RVNL to do horizontal micro-drilling from the left of the tunnel. This will work as a life-saving escape tunnel even in the future – it will be 1.2 metres wide, 168 metres long, and will meet the existing tunnel at around the 300-metre mark from Silkyara side. Machinery for micro-tunneling through horizontal drilling is being transported from Nashik and Delhi
Option-4
Construction of rescue tunnel from Barkot end – One of the option is to construct a rescue tunnel from the Barkot end by THDC (Tehri Hydro Development Corporation) through conventional drill and blast method. Work has commenced. Instead of completing the tunnel with the existing diameter, the THDC will make a narrower tunnel. This will require 483 metres of digging.
Option-5
ONGC to make vertical tunnel – And finally, the Oil and Natural Gas Corporation (ONGC) has been asked to create another vertical tunnel at the 2.3-kilometre mark, which is where the tunnel is complete from the Silkyara side. The tunnel will be around 325 metres deep. Machinery for the vertical boring is being mobilised by ONGC from USA, Mumbai and Ghaziabad.
Rescue team finally home down to first option of horizontal tunnelling from Silkyara end which was fast and easily approachable with advance American technologies . Distance wise also it was only 65 meter compared to all other options. The work commenced from Monday night .
Chronology of Rescue Operation
November 12: As many as 41 workers get trapped as portions of the Silkyara-Dandalgaon under construction tunnel on the Brahmkhal-Yamunotri highway collapsed following a landslide at around 5.30 am on the day of Diwali in Uttarakhand’s Uttarkashi. The district administration launched a rescue operation.
November 13: Chief Minister Pushkar Dhami visited the spot and contact is established with the trapped workers through a pipe meant to supply oxygen to them. Fresh rubble keeps falling from above.
November 14: Steel pipes of 800- and 900-millimetre diameter are brought to the tunnel site to be inserted through the rubble with the help of Auger machine for horizontal digging. However, due to rubble falls from the cavity , two workers sustained minor injuries. The trapped workers are supplied food, water, oxygen, electricity and medicines.
November 15: Dissatisfied with the first drilling machine, the NHIDCL asks for a state-of-the-art Auger machine, which is airlifted from Delhi to speed up the operation.
November 16: The new drilling machine is assembled and installed. It starts working past midnight.
November 17: The machine drills about 24 metres through the 57-metre stretch rubble stretch by the afternoon and four MS pipes were inserted. However, the process again comes to a halt when the fifth pipe hits an obstacle.
Another high performance auger machine is flown down from Indore to assist in the rescue efforts. In evening, a big cracking sound was heard in the tunnel and the operation is suspended immediately.
November 18: A team of officials from the PMO and experts who decide to work on other evacuation plans simultaneously, including vertical drilling through the top of the tunnel to rescue the trapped workers explored .
November 19: Drilling remains suspended. Union Transport Minister Nitin Gadkari reviews the rescue operation and said boring horizontally with the huge auger machine appeared to be the best bet.
November 20: Prime Minister Narendra Modi spoke to CM Dhami over phone to take stock of the rescue operations at the Silkyara tunnel
November 21: Rescuers release the first video of the workers trapped inside the Silkyara tunnel. They were seen in yellow and white helmets, receiving food items sent to them through the pipeline and talking to each other. Two blasts are set off at the Balkot-end of the under-construction tunnel on the Char Dham route, beginning the process of drilling another tunnel – an alternative option.
November 22: Horizontal drilling of 800 mm diameter steel pipes reaches about 45 metres with only 12 metres remaining of the around 57-metre debris stretch. However, the drilling hits a hurdle when some iron rods come in the way of the auger machine in the evening.
November 23: The iron obstruction that had caused a delay of six hours in the drilling is removed in the morning. Rescue operations are resumed. Officials say the 48-metre point has been reached by the drill. But boring through the rubble had to be put on hold again apparently after cracks appeared in the platform on which the drilling machine rests.
November 24: Drilling at the collapsed Silkyara tunnel to rescue 41 men trapped inside for 12 days was halted again on Friday. The officials said the auger drilling machine faced a hurdle, apparently a metal object, soon after drilling resumed on Friday.
November 25: International tunnelling expert Arnold Dix on Saturday said the auger machine engaged for drilling through the rubble at the Silkyara tunnel has busted with rescuers considering other options, including vertical and manual drilling, to bring out the 41 trapped workers.
November 26: Army personnel brought in to remove auger blades from pipe. Rescuers begin drilling into the hill above the Silkyara-Barkot tunnel Sunday. They have to drill down 86 metres to reach the tunnel. By evening, the heavy drilling equipment had bored down to about 19.5 metres.
November 27 : Auger machines were removed from drilling area to clear tunnel for manual drilling. Rat hole miners, specialised in small tunnel burrowing to dig through debris were tasked to clear the last 10-12 meter stretch of horizontal tunnel with the Madras Engineer overseeing it. Vertical drilling reached 36 meter till 1900 hrs.
November 28 : At 1310 hrs , miners achieve crucial breakthrough . At 1912 hrs NDRF team and doctors enter pipe to reach trapped workers.
Triumph Amidst Adversity
At 1928 hrs, Vijay Horo , the first worker to be wheeled out on stretcher through pipe safely. A successful rescue operation of 41 trapped workers in Silkyara tunnel came to its zenith after number of hurdles to see the daylight on 17th day. All 41 were rescued are in healthy state and were send to local hospital to ascertain their basic parameter
