Innovative sewer system benefits Nairobi River Communities

Innovative sewer system benefits Nairobi River Communities

December 8, 2022 0

Scheme: Nairobi Rivers Sewerage Improvement Project Phase 2

Client: Athi Water Works Development Agency

Consultant: MIBP Consultant Engineers

Contractor: Shaanxi Water and Hydropower

Pipe Application: Permanent Trunk Sewer Diversion

An innovative water management solution has become the product of choice designed to reduce the risk of sewer and waste spills for communities in Donholm and surrounding areas of the Nairobi River basin.

The multi-million-shilling project at Donholm, is the first scheme – delivered by Shaanxi Water and Hydropower on behalf of Athi Water Works Development Agency – to involve the use of Weholite HDPE Structured Wall Systems, manufactured locally by Megapipes Solutions Limited at their new factory in Oaklands, Ruiru.

Part of the Nairobi Rivers Sewerage Improvement Project Phase 2 investment programme, Megapipes’ solution will improve the quality of water in the river by stopping spillage and ensuring the safe flow and treatment of sewer and wastewater for surrounding communities.

The spillage of sewerage into the river basin, was first identified by the breakdown of two broken concrete pipes in Donholm. Being live sewers, the best solution was to install a single, more efficient sewer trunk to serve as a conduit for the main trunks along the Nairobi and Ngong rivers.

Weholite was specified after Nairobi based engineering consultants Mangat I.B Patel (MIBP) Limited had utilised the product on the extremely successful Narok Sewerage Infrastructure project in 2021.

Megapipes Country Director, Simon Thomas said, “Water and Sanitation is high on the public agenda, and we are eager to demonstrate the innovative solutions that Weholite can offer communities facing similar issues.”

“Our bespoke designed systems provided the ideal solution for this vital project at Donholm. In addition, to reducing the project timeframe, it also offered cost savings on the overall project.”

Working in collaboration, the team designed a system whereby the two active sewers of concrete DN 900mm and DN 1200mm diameters were relocated and replaced with 375m of DN1500, 50m of DN1200 and 50m of DN800.

The approach of a combined conduit involved the urgent removal of aged infrastructure and

project partners were required to consider careful execution due to:

  • the challenging tight location of the faults,
  • the time sensitive nature of the problem,
  • the risks of materials being damaged or stolen.

The Weholite system provided significant savings on labour, installation time and cost, with an estimated three-fold reduction when compared with traditional materials such as pre-cast concrete pipes. Health and safety were also a key factor. The product prefabricated and then fusion jointed on-site, decreased the amount of time workers spent in the trenches and in confined spaces. The welded joints providing a 100% leak free system.

For this specific project, it was estimated that the volume of trucks required to deliver and off-load the materials would be reduced from 40 to 13 by using Weholite which allows for 28m of DN1500 per truck in 14m lengths, proving to be less disruptive to the surrounding environment and residential area during construction. Disturbance to the community was significantly reduced – meeting one of the main goals of the project.

Simon Thomas commented on the benefits of utilizing Weholite, compared with traditional materials such as concrete. He said: “Our product is significantly lighter than other materials, providing benefits to the water company in terms of time and cost savings, and to the contractor during transportation and installation of the pipes. It also provides unrivaled sustainability with 100-year service life.”

“By working in partnership with water companies such as Athi Water Works Development Agency, we aim to provide durable and sustainable solutions to water infrastructure issues across Kenya. Our increasing partnerships with water companies is a testament to the strength and reliability of the Weholite product”.

The application of Weholite in this project sets a new standard for adopting sustainable technology that is proven to save on unnecessary costs and time. Now the new Weholite HDPE trunk will safely channel sewerage to treatment plants before they reach the river, rejuvenating the area for Donholm and surrounding communities for decades to come.

Simon Thomas
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