Key facts
- Tunnelling expert Arnold Dix advised on the rescue operation at the Trishuli 3A Hydropower Station.
- The tunnel entrance was buried by a massive flash flood, requiring complex methods to locate.
- Rescuers used explosives to clear debris and dug trenches to drain water from the tunnel.
- Two survivors, Sanjaya Shah and Kabir Maharjan, were found and rescued.
- The rescue team is continuing efforts to reach potentially more survivors located deeper within the hydropower station.
Rescuers have successfully extracted two men from a collapsed hydropower tunnel in Nepal following a massive flash flood, a feat described as a "layer upon layer of miracles" by tunnelling expert Arnold Dix.
Dix, president of the International Tunnelling and Underground Space Association, advised Nepalese authorities on the complex operation to reach survivors trapped in the Trishuli 3A Hydropower Station. The flood, which has killed at least 1,300 people, rendered the landscape unrecognisable, burying the tunnel entrance so deeply that rescuers had to locate it using engineering techniques, old maps, satellite imagery, and helicopter footage.
Once the entrance was found, the team faced further challenges. They had to use explosives, a risky measure given the potential danger to survivors, to clear the tunnel blocked by mud and rocks. The Nepalese army managed the precise detonation of explosives to avoid destabilising the structure. Simultaneously, rescuers had to drain the tunnel, which was still full of water, by digging trenches to the nearby river.
A narrow passageway, "a tiny tunnel the size of a person," was then excavated through the debris at the top of the tunnel, utilising the original tunnel's roof for stability and flood mitigation.
In the early hours of Friday, rescuers heard faint voices, confirming the presence of survivors. Sanjaya Shah and Kabir Maharjan were subsequently pulled out alive.
The operation is ongoing, with rescuers needing to dig approximately another 150 meters to reach the main hydropower station. Dix expressed concern about potential debris and flooding at the station, but remains hopeful of finding more survivors, describing their current focus as the "Goldilocks zone"—the uppermost level of the station where survivors might be located. He likened the ongoing effort to a casino game, stating, "If we were playing at a casino, some might say it's time to walk away, but we say game on, time to take on the house."