By Ibrahim Kasita

Engineers of the Bujagali hydropower project have closed the River Nile channel to the left side of Dumbell Island to begin the construction of the 250 Megawatt dam.

The fast-flowing water in the river channel was closed by two cofferdams, one at the upstream end of the island, and the other one at the downstream end, one kilometre further.

A cofferdam is a structure built across the river, using heavy rocks that are not easily washed away by the strong current, and covered by water-impenetrable murram.

To allow the river to flow on, the water was diverted to the right side of Dumbell Island.

John Lockwood, the Bujagali Energy construction manager, said the water between the two cofferdams would be pumped out, emptying the whole left river channel, so that the concrete structure of the power house could be built on the dry river bed.

“For the next two years, all the waters of the Nile will pass through the existing channel on the right hand side of Dumbell Island, while the powerhouse
is built in the dry left hand channel,” Lockwood explained.

He called the successful blocking of the channel a huge milestone in the project. Referring to the Nile as a powerful woman, Lockwood said: “The mighty Nile has yielded willingly and allowed us to build the first cofferdam in her fast-flowing waters when she could easily have swept away man’s efforts to tame her.”

The next step, he added, would be to build a similar cofferdam at the downstream end. Once the left channel is completed, the same process will start on the right channel.

“When we finish, we shall allow water to flow through special gates as we close the other side to empty it. It will also undergo the same procedures.”

Lockwood, however, noted that the development had not yet affected the famous Bujagali Falls, a popular attraction for tourists.
According to the project managers, the construction is ahead of schedule.

“This shows how serious the constructors and the project sponsors are in trying to get the project completed ahead of time,” said Kevin Kariuki, the head of infrastructure of Industrial Promotion Services Kenya, one of the stakeholders.

“The Government accepted not to receive any dividends until the debt is paid back. This positive gesture means that the electricity generated from the project will be cheaper.”

Once the dam is completed, the electricity tariffs will be between six dollar cents and 6.5 dollar cents per unit, as opposed to the current cost of 25 dollar cents.