Weak rock mass collapse causes water ingress at Tarbela T-5 Project, WAPDA says
HARIPUR, November 10 (Daily Global South)- Water entered the under-construction powerhouse area of Pakistan’s Tarbela Fifth Extension Hydropower Project (T-5) after a weak rock mass collapsed during excavation work, prompting the evacuation of workers and temporary disruption at the construction site, according to the Water and Power Development Authority (WAPDA).
In an official notification issued Monday, WAPDA said the incident occurred during excavation of the second bench of the connecting tunnel, where the collapse of a weak rock mass allowed water from the Intake Pit to enter the tunnel and powerhouse area.
All workers were immediately evacuated safely, with no injuries or loss of life reported, the authority said.
WAPDA confirmed that water from the Intake Pit had been completely drained and no further water was entering the downstream work sites. Dewatering operations in the under-construction powerhouse had also started.
Senior WAPDA officials, along with the project engineer and contractor, were assessing the situation to address any challenges arising from the incident.
The authority clarified that reports circulating about the collapse of the T-5 tunnel were incorrect, stressing that the main tunnel, under-construction powerhouse, tailrace culvert and switchyard had not sustained any damage.
The incident triggered public concern following reports and speculation on social media about a possible failure of Tarbela Dam. Deputy Commissioner Haripur Waseem Ahmed also clarified that the dam had not collapsed and said the situation was under control.
Authorities advised residents to remain cautious and follow official instructions regarding water discharge into the river.
The latest incident is the second major construction-related setback reported at the T-5 project within a year. During the 2025 flood season, water released through the service spillways breached a temporary safety bund, resulting in flooding of the under-construction powerhouse area.
The incident has raised fresh questions about the project’s construction schedule and potential financial implications. Further assessment by WAPDA, the engineer and contractor will determine the extent of the disruption and the measures required before work can proceed.
The Tarbela Fifth Extension Hydropower Project is a major WAPDA initiative designed to add 1,530 megawatts (MW) of electricity to Pakistan’s national grid through three generating units of 510 MW each on Tunnel No. 5.
WAPDA awarded the $354.6 million civil works contract to China’s Power Construction Corporation in May 2021.
Upon completion, the project is expected to increase Tarbela Dam’s installed generation capacity from 4,888 MW to 6,418 MW and provide an additional 1.347 billion units of electricity annually.
Initially planned for completion within five years, the project has faced delays, with September 2027 set as its revised completion target.
