Sikkim hydropower tunnel disaster claims 22 lives

The death toll has risen to at least 22 following a methane gas explosion and tunnel collapse at the under-construction Teesta Stage VI Hydroelectric Project in India’s north-eastern state of Sikkim, while rescue teams continue searching for 11 workers believed to remain trapped underground. The accident occurred on 20th July inside the project’s Head Race Tunnel (HRT), approximately 1.5km from the tunnel portal, where workers were excavating part of the water conveyance system that will carry water from the Teesta River to the 500MW hydropower station’s turbines. The project is being developed by state-owned National Hydroelectric Power Corporation (NHPC). Following the incident, NHPC has released the following statement on 21st July: “An unfortunate incident occurred at 1:04pm on 20 July 2026 inside the under-construction Head Race Tunnel (HRT) of the NHPC Teesta Stage VI Hydroelectric Project at Samardung, South Sikkim, when a suspected methane gas pocket trapped or embedded within the rock suddenly ignited/exploded, generating dense smoke and toxic gases. “The project team immediately activated its emergency response protocols. The team is working in coordination with the District Administration, the National Disaster Response Force (NDRF), the State Disaster Response Force (SDRF), local authorities and other emergency agencies to assist with the rescue operation. In addition, a specialised rescue team from the Directorate General of Mines Safety (DGMS) has arrived at the site to support rescue efforts. Our site engineering teams are working around the clock with the authorities to stabilise conditions inside the tunnel and facilitate the rescue operation. “NHPC’s senior management has reached the site and is working closely with the rescue teams and local authorities. Every possible effort is being made to safely rescue the personnel trapped inside the tunnel. “A detailed investigation will be conducted to determine the cause of the incident. We remain fully committed to supporting the rescue agencies and providing all possible assistance to the affected families. “At this difficult and tragic time, the thoughts and prayers of the entire NHPC family are with the bereaved and affected families.” Authorities have said 27 people were inside the tunnel when the explosion occurred. Two workers managed to escape immediately, while the remainder became trapped. Rescue operations involving the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), Sikkim Police, NHPC personnel and specialist mine rescue teams have been hampered by dangerous concentrations of methane, carbon monoxide and hydrogen sulphide, as well as water ingress and unstable ground conditions. Rescuers have reportedly been limited to short periods underground using breathing apparatus. Indian Media sources have reported that rescue teams are concentrating their efforts on a 200m section of the tunnel where officials believe the remaining missing workers may be located. NHPC said operations are continuing around the clock in coordination with local authorities and emergency services. The Teesta Stage VI scheme is one of several major hydropower developments in the geologically complex Himalayan region, where tunnelling projects frequently encounter difficult ground conditions, faulted rock masses and water inflows. Comments: