A rescue operation for eight people trapped in a collapsed tunnel in the Telangana state of India entered the fourth day as the teams faced challenges posed by slush and seeping water.
A team of "rat-hole miners" – experts trained to work in extremely narrow, often hand-dug tunnels resembling rat burrows – joined the rescue mission on Monday.
It marked a significant move as the same team had successfully helped in the rescue of 41 construction workers trapped in a similar collapse after a landslide in the northern Uttarakhand state in 2023.
A part of the roof of the 43km (26.7-mile)-long under-construction tunnel, located in the Nagarkurnool district of the state, collapsed early on Saturday morning. Out of 50 workers inside the tunnel, 43 managed to escape safely but eight remain trapped 14km inside the Srisailam Left Bank Canal (SLBC).
Their condition remains unknown more than 70 hours after the incident as the intensity of seeping water increased while a slush pile-up on the tunnel floor increased challenges.
The “rat-hole” miners are trained in narrow tunnel excavations and use handheld tools for digging through rock. It is a primitive, perilous, and contentious technique primarily employed in India for extracting coal deposits through confined passages. The term is derived from its likeness to rats burrowing through narrow holes.
Rat-hole mining was banned in 2014 by the National Green Tribunal, the statutory body dealing with environmental protection cases. It ruled that the technique was dangerous and unscientific after a case was brought over the deaths of several rat-hole miners, including some children.
Experts who entered the tunnel on Monday reported that the slush wall has risen by about a metre. More mud and slush continued to move toward the tunnel inlet, reducing locomotive access to approximately 11.5km.
Additionally, approximately 3,200l of water per minute is flooding the tunnel, mixing with large amounts of sand, rock, and debris to create more mud and slush. However, this is not a cause for concern as the tunnel is being dewatered, NDTV reported.
Jupally Krishna Rao, a state minister overseeing the rescue effort, said "the chances of their survival are very remote".
The work was temporarily halted late at night on Monday as the teams had to work through thick muck, tangled iron rods, and cement blocks to reach the accident spot in the tunnel, newswire PTI reported.
District official, B Santhosh, on Tuesday said the stability of the tunnel has been taken into consideration before taking any steps as teams from the Geological Survey of India (GSI) and the National Geographical Research Institute (NGRI) joined the mission.
Rescue officials said a twisted and mangled tunnel boring machine is proving to be another setback and removing its front portion is key to accessing the tunnel.
Efforts are also underway to clear the locomotive track, allowing equipment for dewatering and slush removal to reach the collapse site. Additionally, a path is being cleared to transport earthmoving machines into the tunnel.
The tunnel was part of the longest-running irrigation project of the Telangana government but the project has faced numerous setbacks due to financial difficulties and delays in execution. The project was halted for three years and began just four days before the incident.
