New sewerage catchment infrastructure, Addis Ababa, Ethiopia

Project summary

The Addis Ababa Water and Sanitation Development and Rehabilitation Project Office is installing upgraded wastewater infrastructure for 150 km² of the city catchment, which covers 33% of Addis Ababa (approximately 1 million people). Funded by the World Bank, the project is being supported by Nicholas O’Dwyer on all four phases of the project delivery.

The background

The Addis Ababa City Eastern Sewerage Catchment project aims to develop a modern sanitation system to serve the rapidly growing districts of Bole and Yeka in Addis Ababa. The new plants will serve a population of roughly 1 million people once all the connections are completed to the new sewer network system. This population is expected to grow to over 2 million by 2045.

The project is being delivered across 3 initial phases from January 2020 to May 2027. Phases 1 and 2 (2020–2022) of the project focused on feasibility studies and design for the wastewater network and wastewater treatment plant. This included financial evaluation of return on investment and affordability, preparation of draft environmental and social impact assessments and resettlement action plans, conceptual design and tender document preparation for two 50,000 m3 per day wastewater treatment plants, detailed design of over 100 km of trunk, primary and secondary sewers and tender document preparation for the sewer system contracts. This phase also extended to capacity building of the client’s staff in areas including design, construction and operation of wastewater networks and wastewater treatment plants, and project environmental and social requirements.

Phase 3 of the project (2023–present) includes the construction supervision of four sewer network contracts with values ranging from US$13 million (£9.8 million) to US$40 million (£30 million). This also includes the design review and construction supervision of one wastewater treatment plant design–build–operate contract with a value of US$150 million (£113 million).

A future Phase 4 of the project includes supervision of the operation and maintenance service of the two wastewater treatment plants for five years.

Nicholas O’Dywer worked closely with local partner MS Consultancy, harnessing a combination of international expertise and local knowledge to deliver the project.

The challenges

The phase 1 and 2 work to deliver feasibility studies and detailed designs took place in 2020 and 2021, coinciding with the lengthy COVID-19 lockdowns, which made it difficult for the design team to travel to the sites.

The solutions

Digital tools were used, such as optical satellite data to prepare a digital surface and terrain model in lieu of conventional topographical surveys for the feasibility study. This enabled the team to proceed with the feasibility study in 2020, at a time when movement restrictions meant conducting a traditional topographic survey was impossible.

Close coordination between staff at the local partner office in Ethiopia and Nicholas O’Dwyer’s design staff in Dublin was required to deliver the design in a hybrid manner during the COVID years of 2020 and 2021.

The impact

On completion, the new infrastructure will provide sanitation to a third of the city’s population and will bring significant health and environmental benefits to the inhabitants of Addis Ababa and its suburbs.