Construction activities at the Tarbela Fifth Extension Hydropower Project (T-5) have been suspended indefinitely following a breach in a protective bund that allowed a large volume of water to enter Tunnel No. 5 and the under-construction powerhouse area. The incident occurred on Monday during excavation work on the Second Bench Connecting Tunnel. According to the Water and Power Development Authority (WAPDA), a section of weak rock collapsed, allowing water from the Intake Pit to flow into the tunnel and adjoining construction areas, The Express Tribune reported.
All workers at the site were evacuated immediately, and no fatalities were reported. Haripur Deputy Commissioner Waseem Ahmed confirmed that a Pakistani worker was swept away by the incoming water but was subsequently rescued by emergency response teams. Both Pakistani and foreign workers were moved to safer locations.
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WAPDA stated that the water accumulated in the Intake Pit had been completely drained and that no further inflow was reaching downstream work areas. Dewatering operations at the under-construction powerhouse had also commenced.
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The authority rejected reports circulating on social media about a major tunnel collapse, clarifying that the main tunnel, powerhouse, tailrace culvert and switchyard had not sustained any damage. Senior WAPDA officials, engineers and representatives of the construction contractor are assessing the situation to determine the extent of disruption and identify the challenges ahead.
Meanwhile, the Haripur district administration has ordered a high-level investigation into the incident. The inquiry will establish the circumstances behind the protective bund failure and determine whether structural weaknesses or technical shortcomings contributed to the breach. Officials said a decision regarding the resumption of construction would be taken after the investigation report is submitted.
The T-5 extension is a major hydropower development being undertaken by WAPDA at Tarbela Dam. Designed to add 1,530 megawatts of electricity to Pakistan's national generation capacity, the project comprises three generating units, each with a capacity of 510MW.
The project has an approved cost of approximately USD 807 million, with financial assistance of USD 390 million from the World Bank and USD 300 million from the Asian Infrastructure Investment Bank. Its civil works contract, worth USD 354.6 million, was awarded to China's Power Construction Corporation in May 2021.
Upon completion, 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.
However, the project has experienced repeated delays, shifting its original completion schedule to September 2027. It was also temporarily suspended in August 2025 following rising reservoir levels and increased water inflows at the construction site.
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