Pakistan’s Tarbela 5th Extension Hydropower Project has faced a major setback after a government inquiry held the Water and Power Development Authority (WAPDA), the project contractor, and the engineering consultant responsible for the collapse of a cofferdam.
The incident has caused serious delays and a huge increase in the project’s cost. The total estimated cost has jumped from around Rs82 billion to Rs317 billion, an increase of more than 285 percent. The collapse has also delayed the project by at least two years, pushing its expected completion date from 2026 to June 2028.
The 1,530-megawatt Tarbela 5th Extension Hydropower Project is one of Pakistan’s important projects for increasing electricity production from hydropower. However, the latest inquiry has raised serious questions about project planning, supervision, design changes, and the handling of large public projects.
Inquiry Holds All Three Major Parties Responsible
A three-member independent inquiry committee investigated the collapse and found that responsibility was shared among WAPDA, the contractor, and the consultant.
The committee concluded that changes were made to the cofferdam design after the contract had already been awarded. According to the findings, these changes were not properly handled and did not fully follow the technical and contractual requirements of the project.
The contractor proposed a change in the original design. The consultant accepted the revised approach without properly making sure that all technical standards had been met. WAPDA later approved the changes without fully examining whether they were allowed under the contract or whether the new design had important technical weaknesses.
The inquiry found that these failures happened at different levels of the project. Together, they led to the construction of a cofferdam that was more vulnerable and eventually failed.
The committee described the incident as the result of a series of actions and decisions involving all three major stakeholders. It found that the responsibilities clearly mentioned in the project contracts were not properly followed.
What Is a Cofferdam and Why Did Its Collapse Matter?
A cofferdam is a temporary structure built to control or block water so that construction work can continue safely in a dry or protected area.
In a large hydropower project, such structures are extremely important because construction often takes place close to or within water channels. If a cofferdam fails, water can enter the construction site, damage completed work, stop construction activities, and create major financial losses.
This is exactly what happened at the Tarbela 5th Extension project.
The collapse led to flooding at the project site and forced work to stop. The delay then created further problems related to contracts, payments, financing, and construction schedules.
As a result, the impact of the incident was not limited to the damaged structure. It affected the entire project and played a major role in the sharp increase in its total cost.
Project Cost Rises From Rs82 Billion to Rs317 Billion
One of the biggest concerns is the massive increase in the cost of the Tarbela 5 project.
The project was earlier approved at a cost of around Rs82.36 billion. However, the latest revised cost has reached approximately Rs317 billion and may continue to increase.
This represents an increase of more than 285 percent.
Such a major cost increase puts extra pressure on Pakistan’s public finances. It also raises questions about how major development projects are planned and managed.
The project has received around $700 million in financing from international lenders, including the World Bank and the Asian Infrastructure Investment Bank.
Because of the long delay and higher construction expenses, the cost of producing electricity from the project is also expected to rise.
According to concerns raised by the Planning Commission, the average cost of electricity generation from the project over a 30-year period could reach around Rs27 to Rs28 per unit.
This could make Tarbela 5 one of Pakistan’s most expensive renewable energy projects in terms of its generation cost.
The increase is particularly concerning because hydropower projects are generally considered a low-cost source of electricity after completion. However, large delays and cost overruns can significantly reduce those financial benefits.
Project Completion Now Expected in 2028
The Tarbela 5th Extension Project was earlier expected to be completed in 2026. Following the cofferdam collapse and other related delays, the completion target has now been moved to the end of June 2028.
This means Pakistan may have to wait longer for the additional 1,530MW of electricity that the project is expected to provide.
The delay is important because Pakistan needs more affordable and reliable electricity to meet growing demand. Hydropower is also valuable because it can reduce dependence on imported fuels used in some thermal power plants.
Every delay in a major power project can create additional costs. Construction equipment may remain unused for longer periods, contracts may need to be extended, workers and technical staff may have to remain at the site, and damaged structures may need to be rebuilt.
All these factors can add billions of rupees to the total cost.
The Tarbela 5 case shows how one major engineering failure can create a chain of problems that affect the entire project.
Design Change Became a Major Issue
One of the main findings of the inquiry was related to the change in the cofferdam design.
The contractor proposed replacing the original design with a rock-filled structure. The inquiry found that this change was made despite restrictions under the contract.
The revised design was then used across important parts of the project, including the channel area where the collapse later happened.
The inquiry committee found that the consultant accepted the design changes without making sure that the revised structure fully met the required technical standards.
WAPDA later approved the changes when construction was close to completion. However, the inquiry found that the approval was given without properly questioning whether the change was permitted under the contract and whether the new design had technical problems.
This failure in decision-making at different levels became a key reason why all three parties were held responsible.
Major infrastructure projects require strong checks before any important design change is approved. A change that looks simple on paper can have serious consequences if it affects the strength and safety of a structure.
The inquiry suggested that the required level of technical and contractual review was missing in this case.
Flooding Was Not Found to Be the Main Cause
After the collapse, flooding was mentioned as a possible reason for the failure. However, the inquiry committee did not accept this explanation.
The investigators found that the water flow at the time was within Tarbela’s historical range. According to the committee, the flow was not extraordinary and should have been considered in the design of the structure.
The inquiry found that the water levels were also lower than the design capacity that the cofferdam was supposed to handle.
Instead of blaming unusually high flooding, the committee pointed towards weaknesses in the structure itself.
It identified problems related to protection layers and filter arrangements. These weaknesses reduced the ability of the cofferdam to safely deal with normal water conditions.
The findings are important because they shift the focus from natural causes to engineering and management decisions.
If the water flow was within the normal historical range, then the structure should have been designed and built in a way that could safely handle it.
The committee’s conclusion therefore raised serious concerns about the quality of planning, design, approval, and supervision.
Weak Monitoring and Delayed Reviews
The inquiry also highlighted problems in the monitoring of the cofferdam before its collapse.
WAPDA had asked the project consultant for a performance report on the cofferdam in July 2023. Instead of carrying out its own independent review, the consultant passed the matter to the contractor.
The contractor later submitted a monitoring report in October 2024, more than a year after the request was made.
The inquiry raised concerns about this process because an independent consultant is expected to provide an unbiased technical assessment.
When the consultant simply sends such an important request back to the contractor, questions can arise about whether proper independent supervision is taking place.
Regular monitoring is especially important in a large hydropower project where temporary structures are exposed to powerful water flows and difficult working conditions.
An early and independent technical review might have helped identify weaknesses before the structure collapsed.
The inquiry therefore found serious weaknesses in the overall monitoring system.
Questions Raised Over Payments and Compensation
The investigation also examined payments made during the project.
According to the inquiry, some payments were made for temporary works instead of permanent works. This reportedly weakened the government’s ability to seek compensation from the contractor after the major collapse.
This issue could have important financial consequences for the government.
When a contractor is responsible for work that fails, the contract may allow the employer to recover losses or seek compensation. However, irregularities in the payment structure can make such claims more difficult.
The inquiry therefore raised concerns not only about the engineering failure but also about the financial management of the project.
The case shows that technical supervision and financial control must work together. A project can face serious problems if either side is weak.
Problems Also Reported With the Consultant
The consultant working on the project also faced criticism.
WAPDA later ended the consultancy contract with the firm, saying that it had failed to provide a properly qualified project manager. According to the reported findings, staffing problems continued during the consultant’s time on the project.
The inquiry also noted that the consultant issued a notice to end its contract in May 2025 and withdrew its staff from the site.
However, the committee found that the required 30-day notice period under the contract was not properly followed.
The consultant’s role was particularly important because it was expected to provide technical supervision and independent engineering advice.
The inquiry’s findings suggest that weaknesses in this role affected the project’s overall monitoring system.
A Serious Lesson for Pakistan’s Mega Projects
The Tarbela 5 cofferdam collapse has become a major example of how poor decisions, weak supervision, delayed action, and unclear accountability can create huge losses in a public project.
The project involves billions of rupees and international financing. Such projects require strong planning and strict monitoring from the beginning.
The inquiry found that the contractor proposed a design change, the consultant did not properly ensure technical compliance, and WAPDA approved the change without fully checking its contractual and engineering validity.
This chain of decisions resulted in a vulnerable structure and eventually led to the collapse.
The incident caused flooding, stopped construction work, delayed the project, and pushed the total cost to more than Rs317 billion.
Pakistan is already facing economic pressure, and large cost overruns in public projects can place an additional burden on the national economy.
The Tarbela 5 case highlights the need for better planning, stronger technical review, independent monitoring, and clear accountability.
The Way Forward
The inquiry into the Tarbela 5 cofferdam collapse has shown that the project’s problems cannot be blamed on only one party.
WAPDA, the contractor, and the consultant were all found responsible for failures that contributed to the incident.
The government will now need to focus on completing the project while preventing further delays and cost increases.
At the same time, stronger monitoring and strict technical standards will be necessary to make sure similar problems do not happen again.
The revised completion target is now June 2028, but the project’s final cost and future electricity generation cost will remain major areas of concern.
For Pakistan, the lesson is clear: large infrastructure projects need proper planning, qualified supervision, timely decisions, and strict compliance with contracts. Ignoring these basic requirements can turn a project designed to provide affordable electricity into a far more expensive burden.
The Tarbela 5 project still has the potential to add significant hydropower capacity to Pakistan’s electricity system. However, the cofferdam collapse has become a serious reminder of the high price that can be paid when engineering decisions, contract rules, and project supervision are not handled properly.
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