Isimba dam to be shut over defects

The 183-megawatt Isimba hydroelectric dam, located between Kayunga and Kamuli districts, is set to be shut down later in the year to enable the contractor fix technical and structural defects.

The temporary closure, the second within two years, is planned for August-September pending the full onboarding onto the national grid of the 600-megawatts Karuma hydro-dam power, multiple sources said.

China International Water and Electric Corporation (CIWE) built the Isimba plant at $570m (Shs2.2trillion), most of it being loan from China’s Export-Import (EXIM) Bank, and the power facility was commissioned in the run up to the 2021 polls.

However, the emerging catalogue of engineering and operational flaws have raised questions among sector players and other experts on whether inauguration of the critical infrastructure was rushed and for political capital.

In multiple interviews, sources knowledgeable about the matter said planned works necessitating a temporary closure of the facility include fixing water inflow gates to the turbine areas, replacement of powerhouse roof panels and installation of guard lines and painting.

Another key engineering work on the cards is on the concrete erosion beneath the spillway gates reported partially damaged due to the thrust downstream of gushing water from the dam.

This newspaper understands that bureaucrats and representatives of the contractor are discussing whether to rebuild or repair the buffer locks, or redesign and instead erect the component as hydraulic jump to lessen force of the torrents.

Insiders said the works will require lowest levels of water in the dam, meaning a shut down for three or more months is inevitable.

Isimba dam commissioned on March 21, 2019 was briefly shut down in August 2022 over flooding of the powerhouse due to human error during routine maintenance, plunging pockets of the country into blackout.

That fateful day, August 8, 2022, Uganda Electricity Generation Company Ltd (UEGCL) engineers were said to be installing new equipment at Unit (turbine) III, which had been non-functional, when the inflow gate became faulty.

Attempts to manually shut down the gates following malfunction of the alternative crane closure of Unit III’s inflow gate were unsuccessful to prevent inundation, senior officials briefed on the incident said. The frantic efforts followed the failed activation of automated flood control systems there.

News of the latest planned shutdown, sources indicated, comes in the wake of back-and-forth engagements between UEGCL and CIWE, the dam engineering, procurement, and construction (EPC) contractor, over impending remedial works.

Of particular concern to UEGCL, our investigations show, is the contractor’s alleged failure to provide a “master schedule” detailing how and when the defects would be fixed to inform the plant shutdown.

CIWE representatives told Daily Monitor on Wednesday that they have been “begging” since last year to redo the work, but their requests have received no definite response.

“It is not that we have refused to do the work. No. They (UEGCL) told us that we have to wait until Karuma (dam power) is brought on board. They also said that Uganda Electricity Transmission Company Ltd (UETCL) has the final say on the switch-off [of Isimba dam],” one official said.

The representative spoke on condition of anonymity due to sensitivity of the discussions as the hydro-dam project, beyond being engineering works, is meshed through varied diplomatic layers roundly watched by both Beijing and Kampala.

UETCL, the statutory body bulk power purchaser and manager of high voltage lines, in a rejoinder to this newspaper denied involvement in the ongoing haggling between UEGCL and CIWE.

“We buy power that is available for sale to distributors and we have no authority to stop any power generators from switching off their plant for routine maintenance,” Mr Muhammad Lubogo, UETCL’s public and media relations officer, said in response to our inquiries.

However, both the Ministry of Energy Permanent Secretary Irene Bateebe, and UEGCL’s Chief Executive Officer, Dr Harrison Mutikanga, allayed fears that the shutdown would be detrimental.

 “The teams are working closely together with the Owner’s Engineer (Artelia & Kkatt Consults) to progress and close out the pending works,” Ms Bateebe explained, adding that CIWE is “still committed and on site.”

Hard bargain

Dr Mutikanga on the other hand told this newspaper that they were working “round-the-clock” on the matter.

“The key thing is that a master schedule has not been agreed upon. For us to move forward, we need a schedule first,” Dr Mutikanga said last Monday on the sidelines of the company’s launch of the SafetyforStation campaign at Isimba dam.

The campaign encompasses enhancing safety at all power generation plants and focuses on five key pillars; fall from height, struck by and, or contact, with electricity, fire hazards, drowning, and asphyxia.

The plan is to create adequate awareness among staff, foster a safe working environment and establish an effective feedback system.

Speaking at the launch, UEGCL’s board chairperson Proscovia Njuki said the programme is to inculcate in staff 10 non-negotiable at-work behaviours which are derived from the five safety pillars.

The campaign, she noted, aims to “encourage staff to diligently partake of the mitigation measures”.

Asked about reported safety laxity and risk to staff at Isimba power station, UEGCL’s Mutikanga said the core intervention is to create adequate awareness and build capacity while engaging both the contractor and Energy ministry.

Bureaucrats involved in the matter said Isimba dam can only be closed for at least 90 days without plunging Uganda into power crisis, if the shutdown follows full onboarding of the 600-megawatts power from Karuma hydroelectric dam which straddles the parallels of Kiryandongo and Oyam districts.

Its commissioning, which has already been deferred more than once, is now expected in August at the earliest, pending an awaited completion of ongoing works to rectify a litany of structural, wiring and other flaws.

Engineers have conducted both wet and dry tests to ascertain the efficiency of the plant’s six turbines, with each confirmed in form to generat 100-megawatts.

Their supervisors in Kampala as of Wednesday, this week, declared each unit largely good to run after months of phased trials to onboard power from the dam onto the national grid.

UEGCL has demanded that the Karuma contractor rectifies all identified defects before handing the $1.4b (Shs5.4 trillion) plant over to the government.

China’s EXIM Bank funded 85 percent of both dams following a March 2013 meeting between President Museveni and his China counterpart Xi Jinping, although a formal loan agreement was not finalised until mid-2015.

“Isimba was rushed for political commissioning when all issues had not been addressed. We cannot repeat the same [mistakes] on Karuma. Immediately the Chinese hand over the plant [to the government], they [will de-mobilise from the site which makes resolving [emerging] issues challenging,” an official of the statutory power generation agency said.

CIWE in 2013 lost out on the Karuma dam bid to Sinohydro Corp and Kampala instead handed it the tender to construct Isimba dam.

Since 2016, back-to-back engineering audits undertaken to ascertain the quality of works at both dams unearthed, among others, structural and plant defects as well as environmental, health and safety concerns.

Experts blamed flaws at these Uganda-China friendship flagship projects on contractors allegedly trying to cut corners and less-than-satisfactory supervision by Uganda government officials amid unproven claims of inducements.

UEGCL has previously said it was handed supervision of the Isimba project in December 2016 when construction, at 75 percent, was nearly complete.

This newspaper understands that senior officials on both sides have been working behind the scenes to quietly smoothen things to prevent the disagreements from snowballing to the attention of highest levels of governments in both Kampala and Beijing.

This followed a meeting in August 2022, shortly after the Isimba dam flooding incident, during which CIWE officials reportedly agreed before President Museveni to fix the defects.

They have since been “moving in circles”, an official said, ostensibly due to financial constraints.

In the interview on Wednesday, the company admitted to financial squeeze partly because UEGCL has since 2019 held onto its last pay cheque of $16m (Shs62b).

“But we have to use our money to finish the project,” the company official, who requested not to be named because they are not the highest authority, said.

Case unresolved

CIWE officials downplayed the structural risk profile of Isimba dam, saying outstanding issues at the plant are “unit-related defects”— within the turbine areas. The company further poured cold water on claims that the concrete beneath the spillways is washing away.

UEGCL on the other hand maintains that the disintegrating concrete beneath the spillway gates is among the key pending issues at Isimba alongside non-functional firefighting systems.

A spillway gate is a raised adjustable gate to allow controlled release of water downstream whenever water levels in the reservoir — the large lake behind the dam — increase, including the probable maximum flood. 

Officials involved in operation and maintenance of the dam said the concrete foundation requires to be “rock solid” due to the distinct power of the torrents gurgling from the dam side.

In Isimba’s case, both UEGCL and external engineers established previously that the water falling on the concrete at high velocity was causing disintegration. Isimba has five spillways.

Citing back of the envelope figures, sources said planned remedial works at Isimba hydroelectric dam could gross $50m (Shs194b).

Isimba is a run-of-river type dam, one which harvests energy from flowing water, from the adjoining 170 million cubic meters reservoir, to produce electricity.

As debate on whether the concrete beneath the spillway gates is eroding or not lingers, water from the reservoir cannot be stopped for now because it would have adverse effects on the embankment that forms part of the powerhouse, the 10-storeyed structure that shelters the main dam and offices.

CIWE poured cold water on this account, saying both UEGCL engineers and several Panel of Experts (PoEs) members have on several missions dived underneath to inspect the concrete foundation using advanced gadgets and that they found the structure intact.

The company, however, acknowledged that the buffer blocks — that control the high velocity of spillway water cascading downstream – are damaged and need to be redone.

The buffer blocks were initially conceived to control the speed of water for the safety of Mbulamuti ferry that served as an alternate route between Bugobero landing site in Kayunga District and Izanhiro landing site in Kamuli District.

The Uganda National Roads Authority-operated ferry, first commissioned in 2014, has since been suspended following completion of the Isimba bridge, an offshoot of the dam project.

CIWE told this newspaper that design and model tests for the new buffer blocks are underway in Beijing, China.

“All these things have a financial bearing on the contractor’s side. And to be fair to them, it is likely they don’t have this money, but they have to redo the work,” a Uganda government official said.

“Our issue is that they (CIWE) are taking too long.”

A senior official linked the delayed decision-making over the fate of Isimba dam to the expiry of the Contractors’ all risks (CAR) insurance — a construction-related non-standard insurance policy that provides cover for property damage, third-party injury or damage claims.

Under the EPC contract, the defects now presenting teething challenges between the parties should have been fixed during the Defects Liability Period (DLP), which lapsed in September 2022.

Govt, electricity bodies react

Ms Irene Bateebe, Energy ministry Permanent Secretary.

The teams are working closely together with the Owner’s Engineer (Artelia & Kkatt Consults) to progress and close out the pending works.

Dr Harrison Mutikanga, UEGCL’s Chief Executive Officer.

The key thing is that a master schedule has not been agreed upon. For us to move forward, we need a schedule first.

Mr Muhammad Lubogo, UETCL’s public and media relations officer

We buy power that is available for sale to distributors and we have no authority to stop any power generators from switching off their plant for routine maintenance.