Case Study: Matongo Sewer Pump Station

Case Study: Matongo Sewer Pump Station

1. Project Overview

The Matongo Sewer Pump Station serves a predominantly semi-formal and informal residential community in Windhoek, Namibia. The station receives a significant volume of raw domestic sewage containing high levels of solids, rags, and other debris.

The existing pumping installation had experienced persistent operational challenges, including pump blockages, failures, and frequent manual re-priming. These issues resulted in high maintenance requirements, increased labour intervention, higher operational costs, and an increased risk of sewage flooding and environmental contamination.

To address these challenges, the City selected the Wilo EMUport FS 2600 solids separation pumping system as a more reliable and robust solution.

The new system was designed for a significantly increased pumping capacity of 35 L/s at 9.8 m total head, compared with the previous station capacity of approximately 17.3 L/s.

The Wilo EMUport system was successfully installed and commissioned in September 2023.

2. Project Location

• Project: Matongo Sewer Pump Station
• Location: Windhoek, Namibia
• Application: Municipal wastewater / raw domestic sewage
• System: Wilo EMUport FS 2600 solids separation pumping station

3. Background and Existing Situation

The original Matongo Sewer Pump Station was constructed with a wet-sump configuration incorporating wet-installed submersible sewage pumps.

In 2011, the station was upgraded, and two Gorman-Rupp self-priming sewage pumps were installed.

Following the upgrade, the City experienced several operational difficulties. The self-priming pumps did not consistently retain their prime and therefore required frequent manual re-priming.

The incoming sewage also contained significant quantities of solids, rags, and other debris, which resulted in regular pump blockages and failures.

To maintain continuous operation, the City was required to have a dedicated team available at the pump station to:

• Inspect and clean the pumps;
• Remove blockages;
• Clear accumulated solids and rags;
• Manually re-prime the pumping system; and
• Respond to operational failures.

This created a highly labour-intensive operating environment and resulted in increased maintenance and operational costs.

4. Project Challenge

The City required a pumping solution capable of reliably handling raw domestic sewage with a high concentration of solids and rag material.

The new solution needed to address several key challenges:

• Frequent pump blockages;
• High solids and rag content in the sewage;
• Pump failures and unplanned downtime;
• Frequent manual re-priming;
• High labour requirements;
• High maintenance and operating costs;
• Risk of sewer flooding and overflowing manholes; and
• Risk of raw sewage entering residential areas and the surrounding environment.

In addition, the existing station had been designed for approximately 17.3 L/s, while an assessment of current and future sewage inflows indicated that significantly greater capacity would be required.

Considering the characteristics of the catchment area and anticipated population growth, the required peak capacity was increased to 35 L/s.

5. Chosen Wilo Solution

Based on the successful performance of a Wilo EMUport solids separation system at another installation, the City decided to implement the same technology at the Matongo Sewer Pump Station.

The Wilo EMUport system was selected because its solids separation principle is particularly suited to challenging sewage applications where high concentrations of rags, solids, and debris can cause conventional sewage pumps to block.

The system separates problematic solids from the sewage flow before the sewage enters the pump. This significantly reduces the risk of blockages and allows the pump to operate more reliably.

The selected solution therefore directly addressed the key operational challenges experienced with the previous installation.

6. Wilo Product and Technical Solution

The selected system was a:

Wilo EMUport FS 2600 Solids Separation Pumping System

• Station diameter: 2,600 mm
• Station depth: 4,800 mm
• Design flow: 35 L/s
• Total head: 9.8 m
• Pump: Wilo FA10.65E-394 sewage pump
• Motor: FK 202
• Commissioning: September 2023

The EMUport solids separation technology prevents problematic solids and rag material from reaching the pump, reducing the potential for pump blockage and improving overall system reliability.

The increased design capacity from approximately 17.3 L/s to 35 L/s also provided the City with substantially greater hydraulic capacity to manage current sewage inflows and anticipated future demand.

7. Installation and Implementation

A key requirement of the project was that the existing pump station had to remain fully operational throughout construction and commissioning.

Interrupting sewage pumping operations was not considered feasible due to the critical nature of the infrastructure and the potential consequences of sewage overflow.

To overcome this challenge, the new pump station was constructed adjacent to the existing facility.

The new installation was interconnected with the existing inlet manhole and connected to the existing sewer rising main.

This arrangement allowed the new Wilo EMUport system to be integrated into the existing sewer infrastructure while maintaining operation of the original pump station during the construction phase.

The new Wilo system was successfully installed, commissioned, and brought into operation in September 2023.

8. Outcome and Measurable Success

The implementation of the Wilo EMUport system proved highly successful and delivered significant operational, social, and environmental benefits.

Increased Pumping Capacity

The new system increased the station's design capacity from approximately 17.3 L/s to 35 L/2.

This substantially improved the station's ability to manage existing and anticipated future sewage flows.

The increased capacity contributed to a significant reduction in flooding and overflowing sewer manholes, reducing the frequency of raw sewage entering surrounding residential areas and the environment.

Improved Pump Reliability

The Wilo EMUport system demonstrated excellent performance when handling raw domestic sewage containing high concentrations of solids, rags, and other debris.

The solids separation system prevents problematic materials from entering and obstructing the pump.

As a result, the system achieved reliable and uninterrupted pumping operation, with no significant pump blockages experienced.

This represented a major improvement compared with the previous installation, where blockages and manual intervention were recurring operational problems.

Reduced Maintenance Requirements

Following implementation of the new system, maintenance requirements were substantially reduced.

Routine maintenance was primarily limited to weekly inspections, while the need for corrective repairs and unplanned maintenance became minimal.

This represented a significant improvement compared with the previous installation, which required a dedicated team to regularly clear blockages, clean the pumps, and manually re-prime the system.

The result was:

• Reduced labour requirements;
• Reduced corrective maintenance;
• Reduced unplanned intervention;
• Lower operating costs; and
• Improved utilisation of municipal resources.

9. Impact on People and the Environment

The project delivered benefits beyond pump reliability and operational efficiency.

By providing reliable and uninterrupted sewage transfer to the wastewater treatment plant, the Wilo EMUport system significantly reduced the risks associated with:

• Raw sewage spills;
• Sewer flooding;
• Overflowing manholes;
• Sump overflows;
• Environmental contamination; and
• Exposure of the surrounding community to untreated sewage.

The reduction in sewage overflows contributed to improved sanitation and public health conditions for the surrounding residential community.

From an environmental perspective, improved pumping reliability reduced the risk of untreated sewage being discharged into surrounding areas, supporting better protection of the local environment.

10. Conclusion

The Matongo Sewer Pump Station project demonstrates how Wilo EMUport solids separation technology can provide a robust and reliable solution for challenging municipal sewage applications.

By replacing a labour-intensive and blockage-prone pumping arrangement with a dedicated solids separation system, the City achieved higher pumping capacity, improved reliability, reduced maintenance requirements, and lower levels of operational intervention.

The increase in capacity from approximately 17.3 L/s to 35 L/s, combined with the improved solids-handling capability, significantly strengthened the station's ability to manage current and future sewage flows.

Most importantly, the project delivered a positive impact on the surrounding community and environment by reducing the risk of sewage flooding, overflowing manholes, and uncontrolled discharge of raw sewage.

The successful implementation of the Wilo EMUport system at Matongo demonstrates the value of selecting the right pumping technology for demanding wastewater applications and provides the City with a more reliable and cost-effective long-term sewage pumping solution.