Karuma, Isimba Dam Cracks Blamed on Poor Sand

A soil scientist with National Environment Management Authority NEMA says the cracks on Karuma and Isimba hydro-power dams was caused by use of poor quality sand.
Owen Falls Dam constructed in the 1950s. Dr Jerome Lugumira says poor quality sand is to blame for the cracks that developed on Karma and Isimba dams.

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A soil scientist with National Environment Management Authority (NEMA) says the cracks on Karuma and Isimba hydro-power dams was caused by use of poor quality sand.


The cracks with width varying from 0.2 to 1.48 millimetres were noticed in the spillway concrete.


Some engineers blamed the cracks on Karuma dam on shoddy work by Sinohydro Corporation but Dr. Jerome Lugumira, a specialist in soils and land, does not rule out the possibility that poor sand was used.


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Dr Lugumira suggests that the sand had elements of shrink and swell clay which is not recommended in the construction industry. Shrink and swell clay is said to contain vermiculite mineral. Vermiculate is highly porous and is prone to contractions when mixed in cement. 


Cracks at Karuma Hydro Power dam were discovered after 30 percent of the construction work had been done. Similar cracks were reported at the construction of the 183MW Isimba dam.


The cracks at the over two-billion-dollar projects reportedly angered President Yoweri Museveni leading to the sacking of some officials at the Ministry of Energy.


President Museveni later appointed former Electoral Commission Chairperson, Dr. Badru Kiggundu, to head a Project Steering Committee on the two projects. The committee was tasked with fixing the cracks. 


Dr. Lugumira suggests that the two projects could have been started without specifically identifying where the right sand for the projects would be obtained. He explained that there are different grades of sand that can be used for different construction works.


Lugumira says an initiative has not been taken in Uganda to determine what quality of sand is available in the country.


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Lugumira says he is not shocked by the fact that poor sand is causing cracks in dams being constructed in Uganda.  He says some of the biggest dams in United States of America have developed cracks because of geological forces but mostly due to structural inefficiencies in materials.


Engineer Hillary Onek, the Minister for Relief and Disaster Preparedness, in a presentation at the Uganda Institute of Professional Engineers said incidences of cracks in dams most often occur due to hydration heat differential. 


But Onek, who once headed the Ministry of Energy, ruled out tremors as the likely cause. He said there has not been a recorded tremor since construction of Karuma dam started.


There is another side to the cracks at Karuma. A study by Energy Infratech Pvt published by the International Academic Journals Network says the cracks revealed that they were thermal in nature due to heat of hydration.