How IMC are helping to rehabilitate Freetown’s water supply

Since 1961 Freetown’s main water reserve has had the same scour valve, this year we managed to replace this valve to improve the water supply to the Eastern part of the capital city.

Monday 06 June 2022, Kanakasabapathy Pakeerathan (Pakeer)

High quality and sufficient water supply is essential for human health but is often an issue in many parts of the world. Water is at the heart of adaptation to climate change, serving as the crucial link between the climate system, human society and the environment. Improved water supply means a reduction of morbidity and mortality rates associated with water-borne diseases. This has been a huge challenge for countries such as Sierra Leone.

To help address this issue, we have been working on the Freetown Water Supply Rehabilitation project, which is funded by the Foreign, Commonwealth and Development Office (FCDO). 

Nearly 90% of Freetown’s water is sourced from the Guma reservoir, which has a storage capacity of more than 20 million cubic meters and a depth of 66 meters. The Guma reservoir is impounded by Guma Dam, an earthfill dam constructed between 1961 and 1967, located 15km south of Freetown on the Guma River.

Much of the facilities at the Guma reservoir have not been updated since this time. 

The Freetown Water Project has been running since 2017 and after many stages of lockdown, stage 4 of the project resumed in October 2021. This year marked one of the greatest milestones in the project, the replacement of the Dam’s scour valve. 

A scour valve is an outlet pipe or tunnel that runs through the bottom of the dam and is used to control the flow of water. In water distribution networks scour valves play a vital role in draining the water, this is necessary to flush out any contaminants that accumulate along with helping to perform regular maintenance.  

The existing scour system for the Guma Dam has been functioning with reduced integrity for more than 10 years, with excessive external leakage preventing engineers from operating the low-level drain. The old valves were 55 years old and the existing scour system for the Guma Dam has been functioning with reduced integrity with excessive external leakage.

It was estimated that 2 million litres of water were being lost every day. Part of works for the project was to replace the two valves, aiming to allow full operability of the low-level drain and retain the full capacity of the reservoir.

A purpose-built gantry crane powered by batteries was used to transport the seven tonne valves through the tunnel. The valves were specifically designed and manufactured by Blackhall to fit the dimensions of the existing system with associated supporting design completed by the sub-consultant Atkins.  

IMC’s Infrastructure Principal Consultant and Freetown’s Water Project Team Leader Kanaks Pakeer said:

“The purpose of this project is to improve the water situation for approximately 600,000 people in Eastern Freetown by rehabilitating the existing system. We can say that the replacement of the Scour Valve has been major in helping us to achieve that end goal. We are extremely proud of this achievement”.  

Freetown Water team around replacement scour valve

Alongside our key partners, (BAM Nuttall, Atkins, Blackhall and the Guma Valley Water Company) and on behalf of the Government of Sierra Leone, the objective of this project is to increase and provide access to safe, affordable and sustainable water for the capital city’s population and ensure water is fairly distributed across Freetown to meet basic customer demands. The programme is expected to run until 2023. 

Timelapse video and images courtesy of BAM Nuttall.

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