Infrastructure

Sh82bn Thwake Dam Set to Open in December

The government has so far spent over Sh36 billion on the project.

Updated on

February 5, 2024

The construction of phase one of Thwake Multipurpose Dam in Ukambani is set to close by the end of the year, paving the way for water supply, hydropower development, and irrigation activities, a senior official has said.

Water Cabinet Secretary Zachariah Njeru said construction of civil works and other related activities are underway, with the progress of works at 93.6% against a time-lapse of 92.8%.

“The dam is expected to be completed by early December after the construction works commenced on March 27, 2018. The Ministry expects water filling of the dam to take approximately two normal rainy seasons,” Mr Njeru said.

The CS was speaking during an inspection tour of the project on June 18, where he witnessed the final filling of the embankment area, built at the confluence of Thwake and Athi Rivers at the border of Makueni and Kitui counties.

“The filling of the embankment will now pave the way for the settlement of the dam and implementation of the bridge over the embankment, concrete face, installation of the gates and other downstream activities,” he said.

The project, whose contractual completion date was February 6, was expected to be finalized last month after the contractor, China Gezhouba Group Company (CGGC), applied for more time to complete phase one of the project.

The contractor cited various technical reasons, including the El Niño rains, for the request for extra time to complete the project.

More than Sh36 billion has been spent on the construction of the dam’s embankment area.

On December 31, 2021, CGGC successfully diverted a section of the Athi River into two giant tunnels to facilitate on-site excavation.

The company said the tunnels – 700 metres long with a diameter of 12 metres – would be used as substitute waterways where Athi River would change course before later joining the original path to the Indian Ocean.

This would allow the construction of a rock field dam wall that would be 87 metres high and the installation of main and minor spillways for excess water flow.

“We have decided to alter the river course flow so that major excavation works can be allowed when the river base is dry,” CGGC general manager Frank Keeh said.

Thwake Dam, which is considered the second-largest in the country after the Masinga Dam on the border of Embu, Kitui, and Machakos counties, is jointly funded by the African Development Bank (AfDB) and the Government of Kenya.

It will be implemented in four phases.

688 million cubic metres

Phase one, which is underway, involves the construction of an 87m-high dam wall with a 688 million cubic metres storage capacity, and preliminary works for the implementation of the subsequent three phases.

The second phase of the Thwake Multi-Purpose Dam project will involve the installation of a hydropower generation plant, while phase three comprises the installation of water supply, sanitation, and wastewater infrastructure.

The fourth phase will involve the development of the irrigation component.

Through budgetary allocations to the respective ministry, the government will invest Sh59.95 billion in the project, with AfDB contributing Sh21.94 billion.

Thwake Dam will provide water for domestic, irrigation, hydropower as well as industrial activities in the beneficiary counties.

It will mainly serve Makueni County as well as certain parts of Kitui County.