Water surges into Tarbela T-5 work areas after rock collapse

A rock mass collapsed at the Tarbela Dam 5th Extension Project (T-5) construction site on Monday, allowing a large volume of water to enter nearby work areas and forcing authorities to suspend construction activities and evacuate workers.

The incident occurred during excavation work at the 2nd Bench Connecting Tunnel, when a weak rock formation gave way and allowed water from the Intake Pit to flow into the under-construction power house and tunnel area.

The Water and Power Development Authority (Wapda) declared an emergency following the incident. All workers were immediately moved to safer locations. No casualties or injuries were reported.

According to Wapda, the water accumulated in the affected areas was subsequently drained. The authority said no further water was entering the downstream work sites and dewatering operations had begun at the under-construction power house.

Authorities were examining the affected structures to determine whether the incident had caused any damage. Deputy Commissioner Haripur Waseem Ahmed said officials were assessing the condition of the tunnel, power house and other structures at the construction site.

Senior Wapda officials, the project engineer and the contractor were also reviewing the situation to determine the steps required to address any challenges arising from the incident.

Wapda rejected reports suggesting that the main T-5 tunnel had collapsed. It clarified that the main tunnel, under-construction power house, tailrace culvert and switchyard had not sustained damage.

Meanwhile, the district administration issued a public safety advisory following the release of additional water from Tarbela Dam.

Swabi Deputy Commissioner Nasarullah Khan said the additional discharge was necessary due to unavoidable circumstances and was expected to increase the flow and water level in the Indus River.

He urged residents to avoid bathing, swimming and boating in the river to prevent accidents. He also advised people to follow official safety instructions and avoid spreading or believing unverified information.

The latest incident comes months after a major setback at the same project. In July, a government-formed inquiry committee held the contractor, consultant and Wapda responsible for the earlier cofferdam collapse at the 1,530-megawatt project.

The investigation identified unauthorised design changes made after the contract award among the major reasons behind that incident.

The cofferdam collapse had delayed the project by at least two years and pushed its estimated cost up by more than 285 per cent, from Rs82 billion to Rs317 billion.

The T-5 project was originally scheduled for completion in 2026. Its completion deadline was subsequently revised to June 2028, even before Monday’s incident.

With an installed capacity of 1,530 megawatts, the fifth extension is expected to significantly increase electricity generation at Tarbela Dam. The World Bank and the Asian Infrastructure Investment Bank are financing the project with $390 million and $300 million, respectively.

Once completed, the extension will increase Tarbela’s total installed power generation capacity from 4,888MW to 6,418MW.