A tunnelling specialist involved in the rescue operation at a collapsed hydropower tunnel in Nepal has explained how rescuers managed to locate and save two workers trapped underground.
Arnold Dix, who has been advising Nepal’s hydropower authorities, said the rescue at the Trishuli 3A Hydropower Station was achieved through a combination of engineering expertise, careful planning and what he described as “layers of miracles.”
The hydropower station was among several facilities affected by a devastating flash flood along the Nepal-Tibet border, which has reportedly killed about 1,300 people.
One of the first challenges was finding the tunnel entrance, which had been completely buried by the massive landslide and debris triggered by the disaster.
Dix said rescuers relied on old topographical maps, satellite images, helicopter footage, engineering methods and visible landmarks such as power poles to determine where the entrance was likely located.
After successfully locating the entrance, rescuers faced the more difficult task of finding the trapped workers.
The tunnel was filled with mud, rocks and debris, including boulders larger than vehicles. Because of the extent of the blockage, rescuers had to use controlled explosives to clear a path, despite the danger of harming those trapped inside or destabilising the tunnel.
Dix praised the Nepalese Army for carefully managing the explosions to minimise the risks.
Rescuers also discovered that large amounts of water had accumulated inside the tunnel. Excavators and pumps were used to create drainage channels linking the tunnel to the nearby river, allowing the water to be removed.
The team eventually created a narrow passage, roughly the size of a person, through the debris at the upper section of the tunnel. Dix said this approach reduced the risk of flooding because the original tunnel roof could serve as the roof of the newly created passage.
In the early hours of Friday, rescuers heard sounds that appeared to be voices coming from inside.
They called out to the trapped workers, reportedly telling them not to worry because help had arrived. A faint response of “okay” was heard.
Shortly afterwards, Sanjaya Shah and Kabir Maharjan were brought out alive.
However, rescuers believe dozens of people could still be trapped inside, meaning the operation is continuing.
Rescuers push deeper into tunnel
Dix said the team had dug approximately 60 metres from the entrance but still had another 150 metres to cover before reaching the hydropower station deep inside the mountain.
Rescuers are hoping the flood debris did not reach the station itself. If it did, those inside could have been struck by rocks and mud or faced further flooding.
The rescue operation remains extremely dangerous, with the possibility of encountering more water underground. Rescuers also face the threat of another flood sending water into the tunnel from the outside.
Despite these risks, the successful rescue of the two men has boosted the team’s confidence and determination.
Dix said the team is now working towards what he described as a “Goldilocks zone” an upper section of the hydropower station believed to offer more favourable conditions for survival.
With two people already rescued alive, Dix said the team is refusing to give up.
“We got two people out,” he said, adding that rather than walking away, the rescuers were treating the success as a reason to continue the operation.
