HARIPUR, Pakistan: A rock mass collapsed at the construction site of Pakistan's Tarbela 5th Extension hydropower project on Monday, November 9, sending water from an intake pit into an under-construction tunnel and powerhouse area and forcing the evacuation of workers, the Water and Power Development Authority (Wapda) said.
The collapse occurred during excavation of the 2nd Bench Connecting Tunnel, Wapda said in a statement. An emergency was declared, construction was suspended and workers were moved to safer areas. "All workers were immediately evacuated safely," the authority said, adding that there were no casualties.
Wapda said the water from the intake pit had been completely drained out with no further water entering downstream work sites. The dewatering of the powerhouse area had also begun. Senior officers, the project engineer and the contractor were assessing the site.
The authority dismissed local reports that the T-5 tunnel had collapsed, further clarifying that the main tunnel, the under-construction powerhouse, the tailrace culvert and the switchyard had not been damaged.
The incident comes as the 1,530 MW project - Pakistan's flagship hydropower addition - is already under scrutiny over cost and execution. The project was approved in 2017 at about Rs82 billion; its revised cost of Rs316 billion, a rise of 282 per cent, was cleared by the Executive Committee of the National Economic Council in August.
A government inquiry into the collapse of the project's downstream cofferdam in August 2025 held the contractor, the consultant and Wapda jointly responsible, finding that the failure was caused not by flooding but by an unauthorised post-contract change of design from roller-compacted concrete to a weaker rock-fill structure, along with inadequate supervision. The committee was led by Federal Flood Commission chairman Ather Hameed.
The project is financed with about $700 million in loans from the World Bank and the Asian Infrastructure Investment Bank. The Planning Commission has warned that the levelised generation cost could reach Rs27-28 per unit, among the highest for any renewable project in the country, and that completion has slipped to June 2028 from 2026.
(With inputs from media reports)