When it comes to maintaining infrastructure, it is important to have a systematic approach to ensure everything runs smoothly. This is especially true for sanitary maintenance hole (MH) sealing. Serious consequences such as leaks and environmental hazards can result when these structures, which play a crucial role in wastewater management systems, are not properly sealed.
This article introduces effective sealing methods and techniques that can help mitigate potential risks and ensure long-term functionality.
What Is Sanitary Maintenance Hole Sealing?
Sanitary maintenance hole sealing is the process of sealing maintenance holes, also known as manholes and other underground structures. It is a clean water inflow and infiltration (I&I) reduction technique.
Why Seal Sanitary Sewer MHs?
The purpose of MH sealing is to reduce the levels of stormwater introduced into the sanitary sewer system during storm events. This I&I reduction can help to improve the efficiency of the wastewater treatment process, as well as prevent the occurrence of blocked pipes and reduce the risk of sanitary sewer overflow and spills.
What Is the Main Concern with Sealing Sanitary Sewer Maintenance Holes?
There is one main concern with sealing sanitary MHs: the generation of sewer gas. Sewer gas is a mixture of various gases, including carbon dioxide, ammonia, methane, and hydrogen sulfide. Created by anaerobic (oxygen-free) bacteria, these gases can not only produce unpleasant odours, but also pose health risks to workers and members of the community if they are exposed to high concentrations.
If MHs at the surface are sealed, it could prevent oxygen from entering through pickholes and lead to an increase in sewer gases. This is especially significant if there are poor hydraulics (low velocities) and limited airflow at that specific location.
Proper sanitary sewer gas monitoring is necessary to ensure that MHs are effectively sealed and the levels of sewer gas remain within safe limits.
The MH Sealing Approach
The MH sealing process starts with identifying the ideal candidates for sealing, which can have a big impact on the overall effectiveness of the project. It is crucial to investigate and analyze the storm drainage system, including assessing the overland flow and depth of flows above maintenance hole covers during storms.
A dual-drainage modeling approach may be used, which includes a range of techniques such as GIS, topographic surveys, hydraulic and hydrologic analysis, site visits, and interviews with municipal sewer and road operations staff.
All of this data helps ensure that the sealing approach is optimized for the specific needs of the infrastructure and that any issues are identified and addressed before they become major problems.
Gas Monitoring Approach
Sewer gas monitoring involves regular checks of the air quality within MH structures. The standard industry practice includes monitoring concentrations of hydrogen sulfide, oxygen, methane, ammonia, and air pressure within the sealed manholes.
How Can Civica Help with Sealing Sanitary Sewer MHs?
Civica Infrastructure Inc. is a leader in water management solutions for municipalities and land developers. With expertise in sewage water management, Civica recognizes the costly impacts and the environmental repercussions that can arise from I&I in wastewater systems. In addition to sanitary sewer MH sealing services, Civica provides inflow and infiltration inspection, wastewater system modeling, and wastewater monitoring.
Contact Civica today for more information.
Learn more at:
Sanitary Maintenance Hole Sealing and Sewer Gas Generation Monitoring, Town of Newmarket
Methodology of Sanitary Maintenance Hole Inflow and Infiltration
How Design Standards Impact Storm Drainage and Sanitary Maintenance Holes (Part 1)
How Design Standards Impact Storm Drainage and Sanitary Maintenance Holes (Part 2)
Sustainable Stormwater Management – Challenges and Considerations
Real-Time Monitoring for Quantifying Combined Sewer Overflow and Water Quality
City of Toronto’s Sewer Infrastructure and Sewer Capacity Assessment Guidelines
Flow Monitoring in Collection System Modelling (Part 1)
Collection System Modelling Utilizing Flow and Rainfall Monitoring Data (Part 2)
