WAPDA says Tarbela Dam, key structures safe after T5 tunnel incident

ISLAMABAD: The Water and Power Development Authority (WAPDA) on Tuesday said the reliability of Tarbela Dam and its other critical structures was not currently under any threat following the recent incident at the under-construction Tarbela Fifth Extension Hydropower Project.

Water entered a tunnel and the under-construction powerhouse of the Tarbela Fifth Extension Hydropower Project on Monday after a section of weak rock gave way during excavation, prompting an emergency evacuation of workers.

WAPDA Chairman Lt-Gen (retd) Muhammad Saeed reviewed the situation during a visit to the project and inspected the intake structure, tunnel, powerhouse and other key sites.

A spokesperson for WAPDA said that consultants, contractors and WAPDA’s project management briefed the chairman on the current situation, while a detailed meeting reviewed the possible causes of the tunnel incident and measures required to address it.

The meeting considered short-medium-and long-term safety measures, while immediate steps to deal with the situation were finalised and implementation has begun.

The chairman directed consultants to submit a detailed report at the earliest covering all aspects of the incident. He also ordered the immediate completion of remedial measures and the finalisation of a contingency plan.

He further directed officials to develop a strategy to minimise delays to the overall completion of the project.

WAPDA has also ordered a departmental inquiry into the incident to ensure a comprehensive investigation.

Meanwhile, the Ministry of Water Resources, which had sought an initial assessment report from WAPDA, was submitted the report on Tuesday. WAPDA Chairman Lt-Gen Saeed also briefed Minister for Water Resources Mian Muhammad Mueen Wattoo on the incident.

The ministry said the water resources minister had been closely monitoring the situation.

What happened

Water entered a tunnel and the under-construction powerhouse of the Tarbela Fifth Extension Hydropower Project on Monday after a section of weak rock gave way during excavation, prompting the emergency evacuation of workers.

WAPDA had said that all workers were safely evacuated and there was no loss of life.

The incident occurred during excavation of the second bench of the connecting tunnel, when a weak section of rock collapsed, allowing water from the reservoir’s intake structure to enter the tunnel and powerhouse.

The authority said water had been completely drained from the intake structure, while efforts to remove water from the under-construction powerhouse had begun.

The incident comes amid an earlier setback to the project, when its protective cofferdam collapsed in August 2025, allowing water to flood the construction site and forcing work to stop.

WAPDA had also rejected reports that Tarbela’s Tunnel No 5 had collapsed, saying the main tunnel, under-construction powerhouse, tailrace culvert and switchyard had not sustained any damage.

The incident prompted the Khyber Pakhtunkhwa Provincial Disaster Management Authority (PDMA) to issue alerts to officials in Swabi, Nowshera and Haripur after the flow of water in the Indus River increased to 150,000 cusecs. Residents in nearby areas were also advised to stay away from the river as a precaution.

Earlier setback

The latest incident comes after an earlier setback in August 2025, when the project’s protective cofferdam collapsed, flooding the construction site and forcing work to stop.

A subsequent government inquiry held WAPDA, the contractor and the consultant responsible for the collapse, citing unauthorised design changes, inadequate supervision and contractual violations.

The inquiry found that the cofferdam’s design had been changed from roller-compacted concrete to a rock-fill structure, compromising its strength and contributing to its failure.

The earlier incident contributed to significant delays and a sharp increase in the project’s estimated cost, which rose from Rs82 billion to around Rs317 billion, an increase of more than 285 per cent.

What is Tarbela Fifth Extension Project?

The Tarbela Fifth Extension Hydropower Project, also known as T5, is designed to add 1,530 megawatts of electricity generation capacity to the existing Tarbela Dam by converting its fifth irrigation tunnel into a power-generation facility.

Tarbela Dam, built on the Indus River in Khyber Pakhtunkhwa, was completed in 1976 and is one of the world’s largest earth-filled dams. It plays a crucial role in storing water for irrigation, regulating river flows and generating electricity.

The dam initially had an installed power-generation capacity of 700MW, which was expanded through successive extensions involving Tunnels 1, 2, 3 and 4.

The fourth extension, which added 1,410MW, became operational in 2018, taking the dam’s installed generation capacity to 4,888MW.

The fifth extension involves installing three generating units of 510MW each at Tunnel No 5, which was originally constructed to release irrigation water when reservoir levels are low.

The project is expected to supply approximately 1.347 billion units of relatively low-cost and clean hydropower to the national grid annually. Upon completion, it will increase Tarbela’s installed generation capacity from 4,888MW to 6,418MW.

The project is being financed through loans of $390 million from the World Bank and $300 million from the Asian Infrastructure Investment Bank (AIIB). The project is part of WAPDA’s plan to promote green, clean, and cost-effective energy.

WAPDA has said the conversion of Tunnel No 5 will allow water releases to be used for electricity generation while maintaining the tunnel’s irrigation function.

The project is also intended to improve the utilisation of Tarbela’s water resources and help address Pakistan’s growing electricity requirements.