More than 15 days after a portion of the Srisailam Left Bank Canal tunnel (SLBC) collapsed, trapping eight workers inside, the body of one person, identified as tunnel-boring machine operator Gurpreet Singh, was extricated on Sunday night.
Singh was one of the eight men trapped inside the tunnel after its partial collapse on February 22.
A senior official said Singh’s body could be extricated following “very careful” digging and other efforts for over 48 hours. According to the official, the body was buried under 10 feet of silt.
Singh could only be identified based on an earring in his left ear and a tattoo on his right hand.
The search for the remaining workers continues, who were identified as Manoj Kumar (from Uttar Pradesh), Sunny Singh (from Jammu & Kashmir), and Sandeep Sahu, Jegta Xess, and Anuj Sahu (from Jharkhand).
WHAT IS HAPPENING WITH RESCUE OPERATION?
Over 200 personnel from the country’s top agencies renowned for handling rescue operations have been working round the clock inside the tunnel. After 17 days, the rescuers at least hope to find the bodies.
Yet, there hasn’t been any information on those trapped inside. Nearly 10 days ago, Irrigation minister N Uttam Reddy had said the survival chances of those trapped was about 1 per cent.
Experts from the National Disaster Response Force (NDRF), Indian Army and Navy, along with cadaver dogs from Kerala Police, robots and other advanced technology deployed in the operation, faced challenges such as slush and water seepage.
The cadaver dogs, (Belgian Malinois breed which were crucial during the July landslides in Wayanad) which can detect scents from a depth of 15 feet, identified two potential locations of human presence on Friday, and rescue teams worked to remove silt at the identified locations.
DID GOVERNMENT IGNORE EARLY WARNINGS?
Recently, BRS leader K Taraka Rama Rao (KTR) accused Chief Minister Revanth Reddy’s government of ignoring expert warnings about the dangerous geological conditions of the SLBC tunnel.
KTR cited two expert reports that classified the tunnel site as a “red zone.”
He said a 2022 Tunnel Seismic Prediction (TSP) survey by Jaiprakash Associates Ltd and Swiss firm Amberg Tech AG warned of a fault zone between 13.88 km and 13.91 km, highlighting weak rock formations and severe water leakage risks. The recent tunnel collapse occurred precisely in this zone.
The BRS leader said that a separate geological survey conducted in 2022 had also flagged safety concerns. That study, said KTR, concluded that the tunnel construction began without adequately assessing surface conditions.
A 2020 report by Amberg Tech AG, quoted by The Indian Express, similarly identified this area as a high-risk, water-bearing zone with decreasing rock strength.
Despite these warnings, the government allegedly proceeded with the project. The news report also quoted a top official involved in the rescue operation as saying, “The roof caved for three metres around the fault zone.”
Both Jaiprakash Associates Ltd and Amberg Tech have not commented on the 2022 report. It was also unclear whether the report was shared with the Irrigation Department.
Amberg Tech’s website describes TSP (Tunnel Seismic Prediction) as the “most effective system in the world for predicting geological conditions ahead of tunnel excavations.”
According to the website, TSP 303 system software is specifically designed to help in “underground construction” by detecting potential hazards like weak rock formations or water pockets before tunneling continues. It uses an automated process to interpret underground structures and identify different types of rock, the website said.
Geologists say the rock conditions are the same, but more water seepage over the years may have made the tunnel less stable.
WHAT IS THE SLBC PROJECT?
Originally named the Alimineti Madhava Reddy Srisailam Left Bank Canal (AMRP-SLBC) project, it is a large-scale irrigation and drinking water project in Nalgonda District, Telangana.
If completed, it would be the world’s longest bored tunnel without intermediate access, ensuring irrigation for 4 lakh acres and drinking water for 516 villages in Telangana.
It was first planned in 1983 to provide water for farming (irrigation) and drinking to fluoride-affected villages in the area, which was then part of the undivided Andhra Pradesh, using 30 TMC (Thousand Million Cubic Feet) of water from the Krishna River. The SLBC project aimed to transfer floodwater from the Krishna River at Srisailam to Nalgonda through two tunnels spanning 50.75 km.
As part of the project, the water was planned to be supplied by either of the two methods:
- Gravity Scheme Using natural flow through tunnels from the Srisailam Reservoir.
- Lift Scheme Pumping water (lifting it) from the Nagarjuna Sagar Reservoir, requiring electricity to move the water.
The tunnels were designed to be built using Tunnel Boring Machine (TBM) technology instead of the traditional drill-and-blast method, as the tunnel passes through the Rajiv Gandhi Tiger Reserve and a wildlife sanctuary in Amrabad.
The Rs 4,600 crore SLBC project includes a 44-km tunnel, with 35 km already completed. Located 400 m below the Amrabad Tiger Reserve, the tunnel received environmental clearance after the government assured it would have openings at both ends from Srisailam to Devarakonda.
THE ON-AGAIN, OFF-AGAIN HISTORY
In 2004, the government chose the tunnel scheme because it would provide a more reliable, long-term water supply. According to the then Andhra Pradesh government, even though the tunnel method was slower, it was a more permanent solution and the lift scheme was only a temporary fix.
Work on the SLBC Tunnel officially began in March 2008, launched by then Chief Minister (of undivided Andhra Pradesh) YS Rajasekhara Reddy, with an estimated cost of Rs 520 crore.
Despite an initial deadline of 2010, only six feet of tunnelling was completed instead of the planned 12 feet by September 2010.
A project report on the Telangana government’s Irrigation and CAD department website, titled Alimineti Madhava Reddy Srisailam Left Bank, dated May 23, 2020, said only 33.3 km completed out of 43.9 km of the tunnel.
The Telangana government which resumed the work on the SLBC project, aimed to complete it in two years by allocating monthly funds and directing the contractor to excavate at least 400 m.
During an inspection at the Amrabad Tiger Reserve, Deputy Chief Minister Mallu Bhatti Vikramarka stated that Rs 14 crore were needed per month for this pace, requiring around 20 months to finish the tunnel.
THE CHALLENGES OF EXECUTION
The deadline for completion of the project has been pushed back six times, and work has been repeatedly hampered by heavy seepage and hard, abrasive rock formations.
The excavation process has been fraught with delays due to bureaucratic, financial, and geological challenges. According to a September 2024 news report in Telangana Today, since 2006, two 10-m diameter double shield Tunnel Boring Machines (TBMs) were assembled onsite to complete the massive undertaking.
However, progress was slow and difficult due to the tunnel passing through a shear zone, which is an area where the Earth’s crust is heavily deformed due to tectonic forces.
In such areas, the rock formations are often weak, fractured, and unstable, making excavation risky and challenging.
As a result, the tunnel boring machines (TBMs) and other equipment faced frequent mechanical failures because the unstable ground conditions made drilling and excavation much harder than expected.
As of November 2020, both TBMs had excavated 70 per cent of their respective sections, but critical components required upgrades and replacements due to wear and tear.
By September 2024, the government announced plans to resume work soon, targeting completion by June 2026. At the time, 20.5 km of the tunnel had been excavated from one end and 14 km from the other, leaving the most challenging 9.5 km yet to be completed due to persistent seepage issues.
For the past eight months, efforts have been underway to manage the water ingress and stabilise the tunnel structure.
THE ROAD AHEAD FOR SLBC PROJECT
The Telangana government is now considering building an alternative tunnel as an extension to the existing SLBC tunnel to provide additional entry and exit points for future emergencies. However, since the tunnel falls within the Amrabad Tiger Reserve, special environmental clearance from the Centre is required. Despite this challenge, the government sees the SLBC tunnel collapse as a lesson, highlighting the need for a long-term alternative.
Meanwhile, Irrigation Minister Uttam Reddy stated that despite the collapse, work on the project would resume in the next two-three months.
