Isimba Dam defects: Spillway tests to be conducted in China

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The spillway defects at Kayunga district-based Isimba Dam will be subjected to a Physical Model Test (PMT) in China to determine the root cause of the structural issues and whether a third spillway is required, Parliament's Committee on Environment and Natural Resources has resolved.

Committee chairperson Herbert Ariko on March 5, 2025, revealed the decision following an oversight visit and a high-level meeting with key stakeholders, including the energy ministry, Uganda Electricity Generation Company Limited (UEGCL), China International Water and Electric Corporation (the contractor) and Artelia & KKATT Consults (the owner’s engineer).

During a media briefing at Parliament, Ariko said the stakeholders acknowledged the challenge and are determined to resolve it.

“The PMT is a critical step in identifying the cause of the defects and ensuring that we adopt the right solutions. The results of the 1:20 scale model test will inform us about the root cause of the spillway defects, while the 1:40 model test will determine whether the dam requires an additional spillway to meet discharge capacity requirements,” he said.

(L-R) Owners Engineer Atolia representatives; Gamal Abdel Fattah and Marc Davies, Owners Eengineer’s representation and the vice President of China International Water and Electricity Corporation Prof. Wang Yongtian appearing before the parliamentary committee of environment and natural resources at Parliament on March 5, 2025. (Photo by Maria Wamala)

A delegation comprising representatives from the owner’s engineer, the contractor, UEGCL, the energy ministry and a panel of experts are expected to travel to China to witness the tests.

Deadline

Ariko stressed that the exercise must be completed by March 30, 2025, to be followed by technical recommendations which will guide the repair process.

In addition to the PMT, a technical team has been tasked with assessing the measures required to create dry conditions for effective inspection and repairs.

“This is a matter of national interest; we expect all parties to strictly adhere to the agreed timelines so that we can resolve these defects once and for all,” Ariko added.

The committee also resolved that the energy minister will continue to provide overall guidance on the project.

“In the event of any disputes during execution, the minister may appoint a mediator to facilitate amicable resolution, overriding the traditional dispute resolution mechanisms in the engineering, procurement and construction contract,” he stated.

Under the accelerated work programme, the contractor is required to revise the Master Completion Schedule by addressing all comments from the owner’s engineer and submitting a final, approved version to the employer by 30 April 2025. The contractor must also appoint an experienced planning manager to oversee the process in line with contract provisions.

Separate insurance cover

Meanwhile, discussions are underway to establish a separate insurance cover specifically for the spillway works, distinct from the general Construction All Risks Policy.

A joint meeting of the Ministry of Energy, Solicitor General, UEGCL, Insurance Regulatory Authority, the owner’s engineer and the contractor will be convened urgently to finalise the modalities.

“We are taking a comprehensive approach to ensure that all aspects, from technical solutions to financial safeguards are addressed. This dam is critical to Uganda’s power generation, and we cannot afford any further setbacks,” he said.

Energy state minister Sidronius Okasaai said the costs for the resolving of the problem could go up to about $150 million. He said the figures could go down or up depending on what is on the ground.

“One of them is the spill way.  The other is a comprehensive plan to complete the work and owing to insurance and implementation of the work plan… when you look at the demand and supply of electricity in the near future, we are going to the negatives and so getting 183 megawatts off the supply chain will actually cause a disaster,” he said.

Prof. Wang Yongtian, the Vice President, China International Water and Electric Corporation said they are committed to complete the work and ensure quality.