World Bank-Backed Tarbela 5th Extension Project Halted After Protective Bund Breach Floods Tunnel Five

Construction work on the World Bank-funded Tarbela 5th Extension Hydropower Project has been suspended indefinitely after a protective bund breached on Monday, allowing a large volume of water to flood Tunnel Five at the site. Engineers and local authorities evacuated both Pakistani and foreign workers, while emergency teams rescued one worker who was swept away by the incoming water. No casualties have been reported and all personnel were moved to safety.

The district administration has launched an investigation into the cause of the breach, and a high-level inquiry will examine whether a structural weakness or technical fault triggered the failure. Authorities say the next course of action will be decided once the investigation report is received. The suspension adds to an already lengthy timeline of setbacks for one of the country's most significant hydropower schemes.

The project is a major initiative of the Water and Power Development Authority (WAPDA) aimed at expanding electricity generation at Tarbela Dam. It is designed to add 1,530 megawatts of capacity through three units of 510MW each, lifting the dam's installed capacity from 4,888MW to 6,418MW once complete. The approved cost stands at $807 million, with the World Bank providing $390 million and the Asian Infrastructure Investment Bank contributing $300 million.

In May 2021, WAPDA awarded a $354.6 million civil works contract to China's Power Construction Corporation. The project was originally scheduled for completion within five years, but repeated delays pushed the deadline to September 2027. Difficulties in securing a no-objection certificate from the Indus River System Authority for closing Tunnel Five have held up work for years.

Construction was also temporarily suspended in August 2025 after rising reservoir levels and increased water inflows flooded parts of the site. The latest breach raises fresh questions about the project's schedule and the safeguards in place around the tunnel works, though officials have not indicated any revised completion date.

For Pakistan's power sector, the Tarbela extension is a key part of efforts to add low-cost hydroelectric capacity to the national grid amid rising electricity demand. Any prolonged halt to construction could affect timelines for that additional generation and the broader cost of the project.