What happened
NHPC’s own technical paper, written in 2024, had already recorded repeated encounters with flammable gas inside the Teesta Stage-VI hydroelectric project’s headrace tunnels. The paper said gas was first detected in 2009 during excavation by the original developer and was encountered again after NHPC resumed work.
The engineering record becomes important because the recent explosion at the Sikkim site reportedly involved a sudden methane release and a landslide inside the tunnel. The incident killed workers and triggered rescue operations.
Background and earlier position
The Teesta Stage-VI project runs through fractured Himalayan rock, including carbon-rich phyllite. NHPC engineers attributed the gas to the geology of the tunnel route and noted that detectors had recorded methane levels high enough to create a combustion risk.
The same paper also described major instability in the excavation zone, including collapses, cave-ins, and flooded access adits when work restarted after years of stoppage.
Related current affairs
- What caused the tunnel disaster in Sikkim’s Namchi? How did 25 people die? Why is methane trapped in mountain rocks? Why are the Himalayas fragile?
- All is not well: India grapples with another Himalayan tragedy
- Toxic gas kills 20 in Sikkim tunnel, efforts on to save 5 workers
- Sikkim tunnel tragedy toll rises to 15; rescue operation continues
- Toxic gas leak: 20 dead, efforts on to rescue 5 (NHPC tunnel incident in Sikkim)
- 20 dead after blast at under-construction tunnel in Sikkim