The search and rescue operation for eight workers trapped inside Telangana’s SLBC tunnel has encountered a major setback, as excavation efforts on Monday, March 3, failed to locate survivors in areas identified by Ground Penetrating Radar (GPR). Scientists from the National Geophysical Research Institute (NGRI) had previously detected “anomalies” in eight locations, raising hopes that the missing workers could be found. However, rescuers discovered only metal objects.
With this, officials now believe that removing all accumulated debris, mud, and sediment may be the only way to locate the missing workers, though this approach risks triggering another collapse.
The tunnel, spanning 14 kilometres (km), has debris built up from the 13.3-km mark to the accident site. GPR surveys initially pinpointed four critical areas—designated as sections A, B, C, and D—between the 13.3 km and 13.45 km marks. Excavations were launched in three locations, involving rat-hole miners and Singareni rescue teams, but when they reached the target depth, they found no sign of the victims.
Rescue teams now face the challenge of clearing the tunnel of all Tunnel Boring Machine (TBM) metal components, soil, and debris. The first step in this process involves cutting away the rear section of the TBM, which is currently obstructing further excavation efforts. Debris has piled up to a height of three to six meters inside the tunnel, complicating rescue operations.
On March 3, repair work on the conveyor belt system was expedited, and operations are expected to begin by March 4 or March 5. Officials believe that once the conveyor system is functional, it will significantly accelerate debris removal, compared to the current locomotive method, which requires three hours per trip.
The SLBC tunnel collapse occurred shortly after the Congress-led Telangana government resumed work on the long-delayed project. Part of the Alimineti Madhava Reddy Project (AMRP), the SLBC tunnel was conceived in 1983 to transport 30 thousand million cubic feet of Krishna River water from the Srisailam dam to the drought-prone Nalgonda and Nagarkurnool districts. The 44-km-long tunnel, which relies on gravity to carry water, has faced significant geological challenges due to its location in a fractured rock zone and groundwater aquifer.
One of the key obstacles slowing down rescue operations has been the lack of an outlet point. Typically, long tunnels have entry and exit points every five kilometres, but due to the presence of the Amrabad Tiger Reserve, no access points were created along the 44-km tunnel. This has complicated efforts to reach the collapsed section efficiently.
The excavation was being carried out by the US-based Robbins Inc., in collaboration with contractor Jaiprakash Associates. The trapped individuals include two engineers, two machine operators, and four workers. They have been identified as Sunny Singh and Gurpreet Singh of Robbins Tunnel Boring Machines Manufacturing Company, and Manoj Kumar, Srinivas, Sandeep Sahu, Santosh Sahu, Anuj Sahu, and Jagath Khes, all employed by Jaiprakash Associates.