Construction work on the Tarbela Dam’s T-5 hydropower project has been suspended indefinitely after a protective bund breached on Monday, allowing water to flood Tunnel Five and the under-construction powerhouse area. All workers were evacuated safely, while authorities have ordered an investigation into the incident.
The breach occurred during excavation work on the second bench of the connecting tunnel, when a weak rock mass collapsed and allowed water from the intake pit to enter the tunnel and powerhouse area, according to the Water and Power Development Authority (WAPDA).
In a statement, WAPDA said the water from the intake pit had been completely drained and no further water was entering downstream work sites. Dewatering operations at the under-construction powerhouse had also begun.
Senior WAPDA officers, the project engineer and the contractor were assessing the situation to identify and address any challenges arising from the incident.
WAPDA Clarifies Damage Reports
WAPDA rejected reports suggesting that the main T-5 tunnel or other major project infrastructure had collapsed or sustained damage.
The authority clarified that there was no damage to the main tunnel, under-construction powerhouse, tailrace culvert or switchyard.
Haripur Deputy Commissioner Waseem Ahmed visited the project site following the incident and confirmed that water had entered the tunnel after the protective bund gave way.
He said the district administration and rescue agencies immediately evacuated Pakistani and foreign workers to a safe location.
According to the deputy commissioner, one Pakistani worker was swept into the water during the flooding but was rescued by emergency teams. No casualties were reported.
High-Level Inquiry Ordered
Ahmed said construction and development activities at the T-5 project had been suspended indefinitely following the breach.
He added that a high-level inquiry had been initiated to determine the circumstances behind the failure of the protective bund and establish whether structural weakness or a technical fault had caused the incident.
The next course of action would be decided after the investigation report was received, he said.
Tarbela Dam Water Level Rises; Spillways to Be Opened
Major Hydropower Project
The construction work is part of the Tarbela 5th Extension Hydropower Project, a major WAPDA initiative being developed at Tunnel No. 5 of Tarbela Dam.
The project is designed to add 1,530 megawatts to the dam’s installed electricity generation capacity through three generating units, each with a capacity of 510MW.
WAPDA awarded a $354.6 million civil works contract to China’s Power Construction Corporation of China Limited in May 2021.
The overall project had an approved cost of $807 million. Its financing included $390 million from the World Bank and $300 million from the Asian Infrastructure Investment Bank.
Once completed, the extension is expected to generate an average of 1.347 billion units of electricity annually, increasing Tarbela Dam’s installed generation capacity from 4,888MW to 6,418MW.
Repeated Project Delays
The hydropower extension has faced several delays, pushing its expected completion date from the original five-year schedule to September 2027.
In September 2024, a project director informed a Senate committee that delays had occurred for several reasons, including difficulties in obtaining a no-objection certificate from the Indus River System Authority for the closure of Tunnel Five.
The project also experienced a temporary suspension in August 2025 after rising reservoir levels and increased water inflows caused water to enter the construction site.
The latest incident has raised further questions about the project’s construction challenges and timeline. Its resumption and the next steps will depend on the findings of the inquiry and an assessment of conditions at the site.
