Australian tunnel expert Arnold Dix, who played a key role in rescuing 41 workers from the Silkyara-Barkot tunnel in 2023, is drawing on that experience as he leads a complex search-and-rescue operation in Nepal – where massive flash floods on August 26 left a devastating trail.
What happened during Silkyara collapse in 2023
“Right now, in Nepal, we are facing something I have never faced before. “Not one rescue — but multiple potential rescues, unfolding at the same time, in different places, each with its own dangers, uncertainties and lives that may still be saved. More recently, four people, including a Chinese national, have been rescued from the hydropower tunnel. Rescue efforts are ongoing to rescue those still trapped under the debris. Working alongside Nepali and Indian experts, he has been assessing the site and reworking the rescue strategy to reach the underground powerhouse, where those missing are believed to have possibly sought shelter. The tunnel is part of the busy Char Dham all-weather road, a flagship project connecting various pilgrimage sites. Rescue teams established communication and worked to maintain supplies, electricity and water supply. As they were removing debris, they sprayed concrete on the roof to ensure that debris does not keep falling. They then used an auger (a large drill) machine to drill through the debris and insert steel pipes inside which trapped workers would have used to crawl out. The machine was rendered ineffective after a rock came in the way. They then called for a high-powered, US-made auger drilling machine. However, a metallic obstruction, identified as a lattice-girder rib, was encountered in front of the rescue pipe, preventing further insertion. Members of the trenchless team subsequently entered the pipe manually twice to verify that the rescue pipe was clear. “I removed the last rock. I could see them. Then i went to the other side. I couldn’t. They hugged us, lifted us. And thanked us for taking us out. I can’t express my happiness. Celebrations had erupted as locals distributed sweets outside the Silkyara tunnel as trapped workers were being rescued from the tunnel. Twelve rat-miners were conferred the Sarvottam Jeevan Raksha Padak at an event in New Delhi. He added that one does what is right out of a sense of responsibility, even when success is uncertain. “Asian traditions offer another powerful idea: dharma. The test is not simply whether we succeed. It is whether we continue to do what is right when the path becomes harder, the responsibilities multiply, and the outcome cannot be known. “When several lives may depend upon us at once, hope must become discipline, compassion must become action, and duty cannot depend upon certainty of success. East or West, the principle feels the same.
At least 1,380 people have been killed and more than 5,500 are missing, as of September 7, in the aftermath of a deadly flash flood that was triggered by a glacier breaking off, collapsed into a river on the Himalayan border of Nepal and China’s Tibet on August 26, washing away towns and villages and burying roads and highways under piles of mud and debris. On the fateful day of November 12, 2023, at around 5:30 am, a collapse occurred in the under-construction tunnel from Silkyara to Barkot, with debris covering a stretch of around 60 metres near the Silkyara portal entrance, trapping 41 workers inside the tunnel. The Silkyara rescue operations lasted 17 days and all 41 trapped workers were rescued on November 28. After the collapse, the government mobilised rescue teams and equipment to reach the 41 workers trapped behind roughly 60 metres of debris. A 900-mm pipe was initially considered for pushing through the debris, but safety concerns prompted officials to pursue multiple options simultaneously. The trapped workers remained in a completed, roughly 2-km section of the tunnel, where concrete work had already been completed. Other provisions to deliver food and medicines through a dedicated 4-inch compressor pipeline were also made available. On November 12 at 8:45 am , rescuers started clearing rubble using excavators. However, despite spraying concrete, loose material kept falling from the roof of the tunnel and the rescuers could only remove 21 meters of debris. On November 14 at 10 pm , rescuers opted for a second strategy. On November 17 at 9 am , the machine was able to drill through 22 metres of debris, but the operation was paused after it was damaged by a rock in its path. On the seventh day, i.e , November19, rescuers started working on an alternative plan, while also exploring options to ensure supply of food and essential medicines to the 41 people did not halt. The new plan involved creating an alternative route at the top of the mountain to enable drilling vertically from a pre-identified spot on the tunnel to a depth of about 103 metres where the workers were stuck. On November 20, the Defence Research Development Organisation’s robotics team also employed the Remotely Operated Vehicle (ROV) Daksh . On November 21 , the first images of the trapped men emerged as a medical endoscopy camera was pushed through a pipeline drilled into the debris. Some 12 men in helmets and construction worker jackets were captured standing in a semi-circle in the glow of tunnel lights, according to the BBC. On November 22 , NHIDCL resumed auger drilling. The obstruction was successfully cut using gas cutters by 2:30 am . We worked continuously in the last 24 hours.
On November 16 at 10:30 am, the new “state-of-the-art” auger machine drilled through nine metres of debris in its first six hours of operation. At 2:45pm, the rescue team heard a “cracking” sound, prompting the evacuation efforts to remain suspended. On November 18 at 11pm , the evacuation operation remained suspended due to a “strong possibility” of another collapse and damage to the machine. The team considered using a ‘Plan C’, which involved drilling vertically through the tunnel to create a “parallel vertical tunnel followed by a horizontal one and vice versa” to rescue the workers. It is a versatile tool used for detecting and managing improvised explosive devices (IEDs), surveying nuclear and chemical contamination and handling hazardous objects, according to DRDO. I have done it for my country,” he said. “The respect they (trapped workers) have given us, I can’t forget my whole life,” he told HT. Arnold Dix, one of the key experts who helped rescue the workers trapped in the Silkyara tunnel and is now participating in rescue efforts in Nepal, said that while Western traditions describe this as a “duty”, Asian traditions call it “dharma”. Dix said Silkyara taught him never to confuse the unlikely with the impossible, while Nepal was teaching him something more. “We are measured not only by the lives we save, but by the lives we refuse to abandon.”
In a post on X on Monday, Dix said he is facing something he has never faced before. Dix arrived in Nepal on Saturday to join the search for people believed to be trapped inside the Chilime hydropower tunnel. The American-made machine had been requisitioned to speed up efforts to evacuate the trapped workers and was flown in from Delhi in three parts on Wednesday evening.
However, minor vibrations were observed during the operation, prompting the rescue team to slightly retract the auger and reassess the force to be applied before recommencing drilling. Sixteen days into the operations, manual drilling and excavation horizontally using the rat-hole mining method started. Rat-hole mining is a primitive method of extracting coal deposits through narrow, horizontal passages, prevalent in Meghalaya. The name comes from its resemblance to rats burrowing through narrow holes. Munna Qureshi, a rat miner from Delhi, was the first one who reached the other side.
At 1:10 pm , pushing of the ninth pipe commenced, advancing it by an additional 1.8 metres. The development came after parts of a US-made auger machine, which drilled up to 46.8 metres through the debris, got stuck in the rubble, forcing officials to focus on an alternative option, such as vertical drilling and rat-hole mining technique. A team of six rat-hole miners from Madhya Pradesh was called for the horizontal drilling through the last 10-12 metres of debris of the collapsed portion. They began the drilling from inside the pipes, 800- and 900-mm in diameter, pushed inside the tunnel to evacuate workers. The 17-day long wait for the 41 workers trapped in the Silkyara tunnel of Uttarakhand finally ended on November 28 after all workers had been evacuated by the rescuers following a gruelling operation.
The term “rat hole” refers to the narrow pits dug into the ground, typically just large enough for one person to descend and extract coal.
