U’khand tunnel collapse: After 6 days, mission to rescue 40 trapped workers stalls
Rescuers haven’t been able to make any progress since Friday early afternoon because they were clearing rocks, which have come in the way of the machine.
Silkyara (Uttarkashi): Rescuers who have been racing against time to evacuate the 40 workers trapped inside the tunnel for over 130 hours faced another setback on Friday after the high-power auger drilling machine stalled after drilling 22 metres through the debris after its bearings were “damaged”.
The drilling couldn’t make any progress after 9 am in the morning and remained stalled at 22 metres, at the time of writing the copy. The machine was pressed into service on Thursday at around 10.30 am after the previous machine got damaged after a boulder came its way. It was able to make progress of three metres in half and hour of its operation, nine metres in first six hours, 12 metres in nine hours and 22 metres in 20 hours.
Meanwhile, rescuers have also called for an additional auger machine as a backup, which is being airlifted from Indore and is expected to arrive at the accident site by Saturday morning.
The machine has capacity to penetrate through the rubble at 5 metres per hour, however, the impediments on its way is now allowing it to operate at the standard pace.
In a press release, the National Highways and Infrastructure Development Corporation (NHIDC) said, “As of now 22 metre pipe-pushing has been completed. Positioning of Fifth pipe is under progress. The machine is not able to push further as the machine is getting lifted and bearings of machine are getting damaged. Now they are anchoring machines to the platform by providing anchors. The progress of work is being monitored by experts...”
The NHIDC director Anshu Manish Khalkho said rescuers haven’t been able to make any progress since early afternoon because they were clearing rocks, which have come in the way of the machine.
Khalkho mentioned that as part of ‘plan C,’ a group of geological experts was exploring the option of creating a parallel entrance to the tunnel by drilling from the outside. However, he emphasised that their primary focus remains on the current plan, and they are only considering the third plan as a potential alternative.
“A survey team is currently assessing the area to determine suitable locations for potentially creating either a parallel vertical tunnel followed by a horizontal one or vice versa. Once the survey data is available, we will incorporate it into our plans. Initially, we did not conduct this survey as we believed we could navigate through the 60 meters of debris,” Khalkho said.
“However, based on a previous survey, we identified that a minimum drill depth of 103 meters would be required for Plan C. Implementing a 103-metre vertical drill poses risks as it may lead to additional debris falling. Nevertheless, if the current plan proves ineffective, we may consider exploring this alternative option,” he said.
The length of the section of the tunnel where debris had caved in has increased from 50-55m initially, to 60-70m after repeated cave-ins, said a Railway official who didn’t wish to be named.
On the rescue operation being delayed, an NHIDCL official, who also did not wish to be named, said trapped workers have been supplied food, oxygen, and water.
“A person can survive six days without food. But, the trapped workers are getting regular food and water and are mentally strong. We are constantly talking to them,” he said.
Asked about the slow pace, Khalkho acknowledged the fact but expressed confidence that as the workers gain more experience, the pace will naturally increase. “To expedite the process, four-five welders are concurrently deployed,” he said, adding that they want to be “extra cautious” and ensure that the pipes are not misaligned by even by a centimetre.
In the current process, the rescuers will drill through the piled up debris to push 800 mm and 900 mm diameter pipes – one after the other — to create a passage through which trapped workers can come out.
“The pipes, each 6 meters in length, are aligned on the machine and pushed forward, with the auger efficiently drilling through debris and pushing muck backward. While this part of the process is relatively quick, the complexity arises during the alignment and welding of the pipes. The meticulous approach is intentional to prevent any misalignment, even for a centimetre,” he said.
Khalkho said they were expecting a breakthrough after drilling using the machine for around 35 more metres
“We have the consideration in mind that machine runs on diesel and it is being operated in an enclosed space. In this scenario, continuous ventilation through a compressor is mandatory,” he said.
“Diesel machines ideally shouldn’t operate in such confined spaces but there is no other option . The vibrations from the machine and the need for continuous ventilation pose a risk to the equilibrium. That’s why it is important to operate at an optimal speed without rushing,: he said.
In the first four days of operations, two rescue attempts to cut through the wall of rock blocking the tunnel had failed – to the despair of the workers’ families and colleagues.
In the first attempt, rescue workers had tried to dig through the rubble using heavy excavator machines and sought to prevent more debris from falling using the “shotcrete method” (shotcrete is a construction technique that involves spraying concrete onto surfaces using air). However, loose rock and sand kept collapsing, rendering in the strategy unsuccessful. In the second attempt, they tried to create a “safe” passage using an auger machine and fitting in large pipes inside which workers can crawl out. This plan failed as the drilling machine being used was rendered useless as it got damaged after the drill hit a boulder on Tuesday night.
Thereafter, the more powerful machine was flown in Indian Air Force aircraft from New Delhi.