Rescue workers and foreign experts are racing to search for scores of workers feared trapped alive inside a hydroelectric tunnel in Nepal after thick mud buried the facility in last week’s devastating flash floods.
At least 933 workers are missing from various hydropower projects along the Trishuli River, which snakes through several remote and mountainous districts, the country’s disaster authorities said.
It is unclear how many workers were inside the deep, heavily reinforced tunnel when the water flooded. It is also unclear how many of them are still alive, as search and rescue efforts are complicated by bad weather, mud and the loss of critical infrastructure such as roads and bridges.
Nepal and its superpower neighbors China and India have invested heavily in hydropower projects across the Himalayas in recent years, hoping to harness the vast energy potential of the rushing river.
Here’s what we know so far:
About 900 workers are missing from 11 different hydropower projects affected by the floods, according to a list compiled by the Independent Power Producers Association of Nepal (IPPAN) on Saturday.
Each plant presents unique challenges for rescuers to enter in the safest manner. Some have internal tunnels that span several kilometers, and workers inside may be far from the portal. Theoretically, with the room and resources in the tunnel, trapped workers could survive for weeks, but air supply could be another problem.
Extensive work is underway to dig a tunnel at the Trishuli 3A hydroelectric power plant, where 42 people are missing, so rescue teams can search for survivors.
The tunnel leading to the underground power plant there, where dozens of people were working when the floods hit, is more than 4 kilometers (2.5 miles) long.
Australian geologist Arnold Dix, who advised rescue workers at the Trishuli 3A power plant, said it was unclear how much of the tunnel was filled with mud and water. “So you might only need to dig 10 meters, or you might need to dig 100 meters.”
There are many other risk factors, Dix said. If the emergency shutdown system were to fail, the turbine room would fill with water, potentially drowning those inside. And that water can be released by crew members digging, potentially posing a danger to rescuers.
Six people are believed to be missing inside the Chilim hydropower plant, Jenjen Lama, a mountain guide involved in the search and rescue operation, told CNN on Monday.
He shared a diagram of the facility, showing a 250-meter (820-foot) tunnel that continues downhill before connecting to a larger facility containing service bays, control rooms, and hydroelectric transformers.
Rama said rescue teams discovered on Sunday that the tunnel was “completely blocked by deep, muddy sediment and sludge” that eventually reached up to his chest. They had to stop after just 130 meters into the tunnel. Damaged infrastructure has also made it difficult for helicopters to land.
Inside the tunnel, he says, “there’s a kitchen, there’s food… but we don’t know about oxygen.”
As many as 27 hydropower plants were damaged in Nepal, with about 12 of them nearly destroyed, Dix said.
Engineers and search and rescue teams from the Nepal Army and Nepal Police, along with experts from India and China, arrived over the weekend.
The team used a thermal camera mounted on a drone to search for survivors, while locating the tunnel entrance and clearing mud. At the same time, rescue teams drilled a hole in the top of the heavily fortified tunnel.
At the Trishuli 3A power plant, rescue workers managed to open a hole large enough to rappel inside using ropes and harnesses, but there was no response to calls. In the past, air was pumped into the tunnel to feed food inside.
However, breaking through the top of a hydropower plant comes with its own difficulties. “You need special equipment to get through the steel and everything around the turbine room, so there are layers of technical challenges,” Dix said.
The next step will be to send rescue workers into the tunnel loaded with oxygen, medical supplies, communications equipment and cameras, officials said Monday.
At least 279 hydropower plant workers were rescued or managed to trudge out of the mud and mud-filled tunnels.
But survivors, each with their own harrowing experiences, continue to search for answers about their missing friends, colleagues and family members.
One such survivor, Bhakti Ram Bohara, estimated that out of about 1,000 workers, only 100 from his and other nearby projects survived.
Among the missing was his brother-in-law. They worked on the same team, spent weeks at a time away from their families, and sent money back to their home villages.
“His wife is my sister and she’s pregnant,” he tearfully told CNN on Sunday.
Another survivor, Ram Chandra, said he managed to escape from the tunnel by holding onto a ceiling crosspiece as water, concrete and debris swirled around him. It took him and his colleagues six hours to reach the exit of the tunnel.
The devastation could serve as a reality check for governments that are pushing ahead with a boom in building dams, tunnels, highways, railways and bridges across the Himalayas, led by China.
India, and to a lesser extent Nepal, have been hard at work building infrastructure in recent years, pouring hundreds of millions of dollars into developing regions that are highly vulnerable to natural disasters and climate change.
Despite being one of the world’s most ecologically and seismically sensitive regions, the river’s potential to be used for large-scale hydropower projects has long fascinated engineers. The demand for electricity associated with the development of AI may intensify efforts to utilize the region’s rivers.
Experts say that given the severity of the incident and its location on the Nepal-China border, national planners should think more carefully about how to design, locate and scale projects in the region, and should spark a regional debate on shared risk monitoring systems.
