Construction work on the Tarbela 5th Extension Hydropower Project has been suspended indefinitely after a protective bund gave way on Monday, sending a large volume of water into Tunnel Five and the adjoining construction area at one of Pakistan's most important dams.
The breach happened during excavation work on the 2nd Bench Connecting Tunnel, when a weak mass of rock collapsed and allowed water from the intake pit to rush into the tunnel and the under-construction powerhouse area. Officials told Dawn that the collapse of the protective bund triggered a sudden surge of water from the dam's reservoir, and an emergency was declared at the site.
All workers at the site were moved to safety. Haripur Deputy Commissioner Waseem Ahmed, who visited the site with rescue and administrative teams, confirmed that water had entered the tunnel after the bund failed and that Pakistani and foreign workers had been evacuated. One Pakistani worker was swept away by the strong current as the water flooded in, but emergency teams rescued him in time. No casualties have been reported.
The Water and Power Development Authority (WAPDA) said in a statement that the water from the intake pit had been completely drained and that no further water was entering the downstream work sites, while dewatering of the under-construction powerhouse was progressing rapidly. Senior officers, the project engineer and the contractor are assessing the situation, the authority said.
WAPDA also moved quickly to correct reports circulating on social media and other platforms that Tunnel Five itself had collapsed. The authority said there was no damage to the main tunnel, the under-construction powerhouse, the tailrace culvert or the switchyard, and that reports of a tunnel collapse were incorrect. The distinction matters: the failure was in the protective bund holding back water during excavation, not in the tunnel structure itself.
The Haripur district administration has launched a high-level inquiry to determine what caused the breach. Officials said the investigation would examine whether a structural weakness or a technical fault led to the protective bund failing, and that the next course of action would be decided once the inquiry report is ready. Construction and development work on the project will remain suspended until then.
The T-5 project is a major WAPDA scheme being built at Tunnel No. 5 of Tarbela Dam, in Khyber Pakhtunkhwa, designed to add 1,530 megawatts to the dam's installed generation capacity through three units of 510 megawatts each. The approved cost of the project is $807 million, with the World Bank providing $390 million and the Asian Infrastructure Investment Bank contributing a further $300 million. The civil works contract was awarded to China's Power Construction Corporation in May 2021 at a cost of $354.6 million.
The project has a long history of delays. It was originally scheduled for completion within five years, but repeated setbacks have pushed its deadline back to September 2027. Work was also suspended temporarily in August 2025, when rising reservoir levels and increased water inflows flooded parts of the construction site. Difficulties in securing a no-objection certificate from the Indus River System Authority to close Tunnel Five have held up the project for years.
The incident is a serious setback for a project that Pakistan's power planners regard as central to expanding cheap hydropower. Tarbela is the country's largest dam and the backbone of its hydroelectric system, and the T-5 extension is meant to squeeze more generation out of existing infrastructure without building a new dam. Every delay to its completion pushes back the additional 1,530 megawatts of capacity that the national grid was counting on, at a time when the country is struggling to keep electricity affordable and reliable.
For now, the immediate questions are technical ones: how badly the flooded areas were affected, how long dewatering and inspection will take, and what the inquiry finds about the bund's failure. WAPDA's statement that the main structures are undamaged is reassuring, but the indefinite suspension means there is no restart date, and the cost and schedule impact of the incident are still being assessed.
What happens next will depend on the inquiry's findings. If the failure is traced to a specific weakness in the rock or the bund design, engineers will need to rework that section before work can resume safely. If it points to a wider problem with the excavation method, the fix could take longer and cost more. Either way, the project now faces another delay on top of the years it has already lost, and the September 2027 deadline will come under fresh pressure.
Figures in this report were checked at 17:54 PKT on 09 November 2026 against reports from Dawn, The Express Tribune, Aaj TV, News18 and ProPakistani.
