The Importance of manhole renovation in our sewage system

23. March 2025

manholes crucial role in dry weather sewerage

Dry weather sewerage plays a crucial role in the drainage of domestic and industrial wastewater. A key component of this system is the manholes, yet they are often overlooked.

These manholes serve a vital function for the maintenance and operational efficiency of the sewage system. Despite their importance, manholes are frequently neglected in current policies related to the mapping of pipes and collectors and their renovation. This article highlights the necessity of manhole renovation within the Belgian WWTP system, with particular focus on the issues caused by gas formation and the current gaps in policy.

Function and importance of manholes

Manholes, also known as inspection chambers or access shafts, are critical components of underground utility systems, particularly in wastewater infrastructure. They provide essential access points for inspection, maintenance, and repair of sewer networks.

1. Access for inspection and maintenance:

Manholes allow utility personnel to enter the sewer system for routine inspections and maintenance tasks, ensuring the system operates efficiently and identifying potential issues before they become major problems.

2. Ventilation

Manholes serve as ventilation points, allowing gases to escape from the sewer system, thereby reducing pressure and preventing hazardous buildups.

3. Monitoring

They serve as points for installing monitoring equipment to collect data on flow rates, system performance, and other critical parameters.

Problems Associated with Aging Manholes in Wastewater Systems

Environmental and Health Impact

Leaks in sewer manholes can lead to contamination of groundwater and soil. This poses a threat to public health and the environment. In addition, odor problems may arise due to the emission of gases, which reduces the livability of urban areas.

Structural Degradation

Aged sewer manholes can lose their structural integrity due to corrosion and wear, leading to subsidence, collapses, and leaks. This reduces the efficiency of the sewer system, increases repair costs, and causes significant inconvenience for local residents.

Gas formation and safety

One of the major problems with aging sewer manholes is the accumulation of hazardous gases such as hydrogen sulfide. These gases can have serious consequences:

Corrosion: These gases can cause accelerated corrosion of manholes and pipes, undermining the structural integrity of the system.
Safety risks during inspection: Hydrogen sulfide is toxic and, at high concentrations, can cause respiratory problems and even death.

current situation and policy gaps

Lot of countries in the EU are currently in the process of mapping its sewer infrastructure. However, this effort mainly focuses on pipelines and major infrastructures, often overlooking sewer manholes. This results in a lack of insight into the condition of these critical components and a missed opportunity to improve the overall efficiency and safety of the sewer system.

policy and action recommendations

Inclusion of Manholes in Sewer Maps: To begin with, it is essential that manholes are included in sewer mapping and inspection programs. This will help provide a more complete picture of the condition of the sewer system and support the prioritization of renovation and maintenance efforts.
Regular Inspections and Monitoring: Regular inspection and monitoring programs should be established for manholes to detect early signs of wear and gas buildup. This can be achieved through the implementation of sensor technology and periodic physical inspections.
Technological Innovation and Renovation: Innovative renovation techniques, such as the use of durable, resistant materials and solutions, should be applied. This will extend the lifespan of manholes and enhance the overall reliability of the wastewater system.