After 17 days of an intense rescue operation — clocking at 400 hours, delayed by a series of snags and overshadowed by equal parts hope and despair — the 41 trapped workers are on the verge of being pulled out of the collapsed part of the under-construction Silkyara tunnel in Uttarakhand’s Uttarkashi.
The breakthrough came on Tuesday when rescue workers managed to drill through the 60-metre stretch of rubble a little after 1.30 pm, using the rat-hole mining technique. Less than an hour later, Uttarakhand chief minister Pushkar Singh Dhami said the process of laying the escape pipe into the drilled passage was complete.
At the disaster site, the mood is upbeat over the imminent end of the multi-agency rescue operation. An eight-bed makeshift health centre has been set up inside the tunnel to provide immediate medical care to the workers after their evacuation. Ambulances have lined up at the mouth of the tunnel to rush the rescued workers to the community health centre about 30 km away, after the initial checkup at the site.
The workers got trapped inside under-construction tunnel on November 12, when a section on the Silkyara end collapsed most likely due to a landslide.
Here is a timeline of the disaster and rescue operations:
Day 17, November 28
Rescue workers drill through the 60-metre stretch of rubble, using rat-hole mining technique, a little after 1.30 pm. Laying of the pipes is complete and stretchers are taken inside the mouth of the tunnel. NDRF personnel enter the steel chute and bring out the workers one-by-one. Going by the practised drill, each worker lays on a wheeled stretcher and is pulled by rescue workers outside using ropes. Ambulances are lined up at the mouth of the tunnel to rush rescued workers to a community health centre. Vertical drilling, the simultaneous drilling operation to reach the workers from above the tunnel, is called off. Doctors are standing by and arrangements have been made to fly the workers to more advanced hospitals, if needed.
Day 16, November 27
Rescuers bore 36 metres into the hill above the tunnel by evening as two teams of seven and five men, who are experts in the technique of rat-hole mining, are now at the site after they are called in by two private companies involved in the rescue operation. The experts have been called in for manual drilling and horizontal excavation through the last 10 or 12 metres of debris. About 40 percent of the 86-metre vertical drilling required is done. For the horizontal through-the-rubble option, officials decide that the final stretch will be handled through a manual approach in which individual workers will go into the escape passage with drills, as well as gas-cutters to tackle obstacles like iron girders. Another 8-inch shaft being drilled from a nearby point reaches about 75 metres down. This probe, also expected to act as a supply line for the trapped workers, indicates that there are no serious geological obstacles for the main shaft up to this point. The vertical drilling, however, encounters some water underground and dewatering is carried out. It does not, however, seriously affect the operation. Principal secretary to prime minister, PK Mishra; home secretary Ajay Bhalla; and Uttarakhand chief secretary SS Sandhu take stock of the operation while Mishra speaks to the trapped workers, assuring them that multiple agencies are at work to evacuate them and they should remain patient.
Day 15, November 26
Rescuers begin drilling into the hill above the tunnel, boring nearly 20 metres on the first day of adopting the new approach. The vertical approach is one of five options on which preparatory work began some days ago. As the drilling progresses, 700-mm wide pipes are being inserted to create an escape passage. A little distance away, a thinner, 200-mm probe is being pushed in. It has reached the 70-metre mark. The vertical boring option was picked as the next best alternative after the latest in a series of snags, which hit the horizontal drilling operation from the Silkyara-end, where an estimated 60-metre stretch of rubble faced rescue workers.Individual workers have been entering an incomplete escape passage, in which a steel chute has been inserted, to cut through and bring the stuck blades and the auger’s shaft out in pieces. A plasma cutter is airlifted from Hyderabad to supplement the gas cutter. A team from the Defence Research and Development Organisation (DRDO) and army engineers from the Madras Sappers also reach Silkyara. Drilling is also being carried out from the Barkot-end of the tunnel, and the work has progressed about 10 out of 483 metres.
Day 14, November 25
Mobile phones and board games are sent in for the 41 trapped workers to alleviate stress. The blades of the auger machine drilling through the rubble gets stuck in the debris, forcing officials to consider switching to other options. According to international tunnelling expert Arnold Dix, the auger machine is busted. Officials now shift focus to two alternatives — manual drilling through the remaining 10-12 metre stretch or drilling down around 86 metres from above.
Day 13, November 24
Drilling was halted again in yet another setback. The auger drilling machine faces a hurdle, apparently a metal object, a little after drilling resumed, a day after officials put the operation on hold following technical problems. Those problems were set right earlier in the day and the 25-tonne machine was restarted in the evening but the boring continued for about an hour before the drill bit hit the metal girder.
Day 12, November 23
Boring through the rubble is put on hold again after cracks appeared in the platform on which the drilling machine rests, in a fresh hurdle. This came hours after the operation resumed earlier in the day, following a six-hour delay to cut through an iron girder in the way of the auger machine. It is the third time that the drilling exercise is halted since the rescue mission began on November 12. The drilling is stopped to stabilise the platform on which the 25-tonne machine is mounted, as some cracks have apparently appeared in the structure.
Day 11, November 22
Ambulances are put on standby and a special ward at a local health centre is readied in the evening. In a late evening development, drilling of steel pipes through the rubble hits a hurdle when some iron rods come in the way of the auger machine. Till 6 pm, up to 44 metres of an escape pipe have been inserted into the debris of the collapsed stretch. A team of the National Disaster Response Force (NDRF) is spotted entering the tunnel in the evening. A team of 15 doctors, including chest specialists, is deployed in anticipation of the evacuation. Relatives of workers who have spoken to them through a new six-inch pipeline express optimism. “Today, we were taken inside the tunnel and we spoke to our family member. Sonu repeatedly told me not to worry now and that we would meet soon,” said Devashish, whose brother-in-law is among the 41 workers. “We called him on Diwali but could not reach him. His colleagues told us that his mobile phone was damaged. Later, we saw his name in the newspaper and learnt that he was trapped inside the tunnel,” he added. The second lifeline is being used to ensure an ample supply of food items like rotis, sabzi, khichdi, dalia, oranges, and bananas in the tunnel.
Day 10, November 21
The first visuals of the 41 workers trapped inside emerge. According to officials, focus remains on digging horizontally through the debris of the collapsed stretch but rescue workers continue to prepare for other options, including drilling from above the tunnel to reach the workers. At the disaster site, a video clip captured by an endoscopic camera sent in through a new six-inch wide pipeline brings some hope to relatives camping there for days. The pipeline was pushed late on November 20 through 53 metres of debris – the collapsed stretch. In the video, workers wearing yellow and white helmets are seen receiving food items sent to them through the pipeline and talking to each other. Officials watching them on a screen are heard giving instructions, asking them to clean the lens. The workers are told to come near the camera and use walkie-talkies, apparently sent down earlier. The camera is then pulled back up so that water can be released under pressure to clean the pipeline.
Day 9, November 20
Rescuers push a six-inch-wide pipeline through the rubble, the “first breakthrough” at the site to help supply larger quantities of food and possibly allow live visuals. A four-inch existing tube was being used to supply oxygen and items like dry fruit and medicines. Drones and robots from the Defence Research and Development Organisation (DRDO) are brought to the site to look into the possibility of other escape routes. The first machine for construction of a vertical rescue shaft, possibly around 80-metre deep by drilling from near the hilltop, also reaches the tunnel. A road to the hilltop is laid, and the Oil and Natural Gas Corporation (ONGC) arranges for more equipment. Also, work starts on drilling from the other side, the Barkot-end, of the tunnel. International tunnelling expert Arnold Dicks also reaches the disaster site to conduct a review. The pipeline development comes on the day Prime Minister Modi called up the CM to take stock of the rescue operation.
Day 8, November 19
Rescue work is put on hold as the agencies involved in the effort set themselves up for the next stage – adopting multiple approaches to reach the 41 trapped men inside. A road to the top of the hill is laid in a single day for digging a vertical shaft down into the tunnel.
Day 7, November 18
Drilling does not resume on Saturday as experts feel that the vibrations created by the diesel-driven 1,750-horse power heavy-duty American auger inside the tunnel might cause more debris to collapse, posing a risk to the lives of the rescue personnel. Alternative options are explored by a team from the PMO and experts who decide to work on five evacuation plans simultaneously, including vertical drilling through the top of the tunnel to rescue the trapped labourers.
Day 6, November 17
Working overnight, the machine drills about 24 metres through the rubble by the afternoon and four MS pipes with a length of six metres each are inserted. The process comes to a halt when the fifth pipe hits an obstacle. Damage to the machine is also reported. Yet another high-performance auger machine is flown down from Indore to assist in the rescue efforts following a request from the NHIDCL. In the evening, the NHIDCL reports that around 2.45 pm, during the positioning of the fifth pipe, a big cracking sound was heard in the tunnel and the rescue operation suspended immediately. The sound creates panic among the rescue team members. An expert involved in the project warns about the possibility of further collapse in the vicinity. Subsequently, the drilling and pipe-pushing activity is stopped.
Day 5, November 16
The high-performance drilling machine is assembled and installed. It starts working past midnight.
Day 4, November 15
Dissatisfied with the performance of the first drilling machine, the NHIDCL asks for a state-of-the-art American auger machine, which is airlifted from Delhi to speed up the rescue efforts.
Day 3, November 14
Steel pipes of a diameter of 800 and 900 mm are brought to the tunnel site to be inserted through the rubble with the help of an auger machine for horizontal digging. However, the efforts suffer a setback when more rubble falls from the cavity created by the cave-in and causes minor injuries to two labourers. A team of experts begins a survey of the tunnel and surrounding areas for soil testing. The trapped workers are supplied food, water, oxygen, electricity and medicines as some of them complain of nausea and headache.
Day 2, November 13
Contact is established with the trapped workers through a pipe meant to supply oxygen to them and they are reported to be safe. Rescue efforts continue as Dhami visits the site. Not much progress is made in removing the debris accumulated on the collapsed part of the tunnel as fresh rubble keeps falling from above, further complicating the task of the rescuers. As a result, the debris accumulated in an area of around 30 metres spreads to 60 metres. A strategy is devised to stabilise the loose soil inside the tunnel applying the method of shotcreting (spraying concrete) and then insert large-diameter steel pipes through the rubble to prepare an escape passage.
Day 1, November 12
The labourers get trapped as portions of the under-construction tunnel on the Brahmkhal-Yamunotri highway collapse following a landslide around 5.30 am on the day of Diwali. Rescue efforts are launched by the district administration and arrangements made to supply oxygen, electricity and eatables to the trapped labourers through air-compressed pipes. Multiple agencies, including the NDRF, State Disaster Response Force (SDRF), Border Roads Organisation (BRO), project executing agency NHIDCL and Indo-Tibetan Border Police (ITBP), join the rescue efforts.
(With PTI inputs)
