SMEC was engaged by the Ministry of Water and Environment to provide design review and construction supervision of the Nyamugasani Water Supply and Sanitation Project, introducing a modern piped water system to serve water stressed communities.

Inheriting a design from 2016, SMEC undertook redesign to accommodate plans for a small run of the river hydropower facility, set to be located near one of the proposed water treatment facilities. In tackling the design SMEC needed to overcome gaps in data and undertake further studies to understand the river hydrology.

Understanding customary land ownership in the project area was another important consideration in navigating complexities related to customary tenure and the nature of occupancy.

Solution

The primary water source is the Nyamugasani River. The proposed water distribution network extends 128 km and includes 34 break pressure tanks and eleven water storage tanks with a total capacity of 8,021 m3. As part of the design review SMEC undertook:

• Fresh geotechnical investigations for two intake sites, Nyamugasani and Murasegi
• Hydraulic, process, structural and electromechanical design two conventional water treatment plants
• Hydraulic and structural design of 82km high pressure transmission main with two break pressure tanks
• Geotechnical studies to assess conditions at eighteen sites to identify optimal locations for eleven water storage tanks
• Structural design of eleven water storage tanks each with a 3,025 m3 capacity
• Hydraulic and structural design of 168 km distribution main with thirty-four break pressure tanks to help manage water pressure over the hilly terrain
• Hydraulic design included offtake from SMEC determined the site location and interconnecting transmission mains.
• Detailed design report and construction management plan in accordance with FIDIC red book conditions of contract.

Site analysis and investigation

SMEC undertook detailed materials analysis and simulation modelling of pipe sizes to inform the design criteria and performance specification.  The infrastructure incorporates a mix of gravity-fed piped water from river sources and motorised piped water schemes from surface water sources. The design included allowance for integrated rainwater harvesting, surface runoff harvesting, and solar-powered mini-piped water schemes.

Field investigations were carried out to identify geological conditions, which informed the hydraulic and structural design of the water supply structures. Hydrological analysis was undertaken to determine the viability of the water source and its capacity to meet the intended design flow. Socio-economic analysis was undertaken, with over 750 respondents providing input ascertain a thorough understanding of projected water demand.

Weir and Diversion sequence

The design proposes two ogee weir structures to help control the river flow, creating a more stable area for the water treatment plant’s intake points. Following assessment of the river hydrology SMEC identified the need to disperse the water intake across two sites to balance the draw of water.

SMEC undertook further studies to assess the amount of water that could be drawn sustainably for each intake. The layout was designed to optimise constructability and resilience during flood bursts. The diversion sequence ensures that the river is restored to its original path minimising ecological impacts.

Water Treatment

The water treatment plants were a major consideration in the design specification. Multiple treatment and filtration processes were assessed to ensure optimal operational and sustainability needs. Large sedimentation tanks 30 x 10 x 2.5 metres will remove suspended solids. Two rapid sand filters further purify the water. A backwash tank with a capacity of 350 m³ will also facilitate filter cleaning.

The layout of the treatment plant needed to consider natural water courses, gradient, topography, cut-and-fill requirements, access roads and protection of the site from flooding. The scope also included design and supervision of power supply and electrical works for solar and generator-based power supply.

Sanitation

As part of the wider sanitation improvement program, SMEC provided design and construction supervision of over 18 new water-borne toilets in schools, health facilities, and public places. SMEC developed a detailed sanitation design manual to inform sizing of pipes and septic tanks. This was an important aspect of the project to improve hygiene practices in the townships.

Knowledge transfer

Another key aspect of the project is to strengthen institutional capacity to improve service delivery and resources management. SMEC has prepared a Capacity Building Plan covering improvements in policy and regulatory frameworks, organizational arrangements, organizational capability, and human resources.

The piped water schemes in the supply area are managed under the Community Based Monitoring System (CBMS) model, indicating a design approach that aligns with local community structures and management systems. The system ensures community is part of the management of the water resources which actively fosters a sense of ownership and adoption.

Impact

The project aims to improve water supply and sanitation services in the Kasese district of Uganda, benefiting an estimated population of 122,764. The new infrastructure will provide adequate and sustainable provision of water for these areas until 2045. SMEC’s design has enabled the client to plan and package the construction across four phases, enabling funding to be staggered with priority works completed first.

• Phase I – Two no. intake points and water treatment facilities, raw water mains, transmission and distribution covering Kyarumba, Kyondo and Lake Katwe Sub Counties
• Phase II – Transmission and distribution to cover Kisinga and Parts of Lake Katwe sub counties and Hydraulic design of Nyateke reservoir
• Phase III – Transmission and distribution to cover Mukunyu and Nyakatonzi Sub Counties
• Phase IV – Transmission and distribution to cover parts of Muhokya and L. Katwe sub counties

In preparing the design and specification, SMEC engineers placed emphasis on the sustainable utilisation of raw water sources, use of smart water treatment technologies, clean energy and development of climate resilient systems. Other notable impacts of the project include:

• Transferring knowledge and skills to sector professionals in contract management, safeguard management, and water and sanitation infrastructure
• Development of an Integrated Water Resource Management approach, considering the water, land, and environment to ensure sustainable water use and conservation
• Incorporation of climate change adaptation measures, such as considering future water demand projections based on population growth and climate change scenarios.
• Community Participation and Ownership: The project emphasizes community involvement in planning, implementation, and management to promote ownership and sustainability.
• The construction of 18 water-borne toilets, with 16 in schools and health facilities and 2 in public places, will contribute to improved sanitation infrastructure. As part of the community engagement program the project will embed improved sanitation and hygiene practices in households, communities, and rural growth centers.
• Gender Mainstreaming: The design considers gender-specific needs and ensures equal access to water and sanitation services for men, women, and vulnerable groups.