How to inspect municipal sewers
Why and how often should sewers be inspected?
A timely sewer inspection saves costs and avoids problems that otherwise have to be solved when tackling emergencies and refurbishment. How and when should sewers be inspected?
Sewer inspection is an important element of maintenance and prevention in municipal sewer systems. As you may be aware, a sewer issue can escalate into a severe emergency in a matter of seconds, with sewage suddenly flooding areas where this should never occur.
Sewer inspections help in addressing emergencies and, more importantly, in preventing them. Inspections should never be overlooked and should occur regularly across the entire wastewater infrastructure.
Two crucial reasons why sewers should be inspected
When inspecting sewers, trained operators usually collect visual information for the purpose of assessing the condition of a pipe or other parts of wastewater infrastructure. There are two principal reasons why sewers should be visually inspected.
1. Quick repair of an emergency in a sewer pipe
Failures and/or emergencies constitute a standard reason as to why sewer inspection is a necessary part of caring for urban infrastructure. It is usually obvious that something is not right with sewers, but it is not always clear what the problem is.
When urban sewer systems are involved, huge problems may occur if sewage leaks into nature or contaminates water. A rapid sewer inspection is essential in order to identify and rectify the problem.
2. Identification of potential problems during routine maintenance
It is much better to inspect sewers proactively as part of a regular cycle of wastewater infrastructure maintenance. Wastewater systems age and the likelihood of a failure increases with every passing year. This is why regular video inspections and cleaning of sewers are in the interest of municipalities.
Further reasons for sewer inspection
- Reoccurring blockages in sewers – determining the cause
- Land sinking near sewer routes
- Damp walls of buildings
- Sewer acceptance following repair
- Acceptance of newly built sewers
- Determining the direction and incline of sewers using tracing equipment
- Finding branches, bends, hidden shafts, defects, and other items inside sewers
- Revealing illegal connections to sewer systems
Methods of inspecting municipal sewers
Inspections of municipal sewers are similar to those of household drainpipes – the purpose is to collect data in order to assess the condition of the pipe. However, municipal infrastructure is much more complex and so the inspections should be conducted by an expert company.
Heritage method of sewer inspection – physical entry to piping
In the past, the only way to check a pipe was by physically entering it with a torch. The inspector personally surveyed each square decimetre to detect irregularities.
Nowadays, new technologies allow operators to obtain high-quality visual data without having to go under the ground.
Video inspection of sewers
Video inspection of sewers is a common inspection method. In larger sewer systems, the camera is connected to a cable and controlled remotely. The output is a video recording that provides visual information on the condition of the pipe. Once the visual data is collected, the inspector evaluates the video and draws a conclusion.
Modern sewer inspection cameras can achieve the following:
- Automated and remote (manual) focusing and zooming
- Aperture control
- Turning the camera crawler inside the pipe.
Inspection using modern sewer crawlers
Video inspection of a sewer is the fastest and most efficient method of detecting issues in pipes. Cutting-edge sewer crawlers can be adapted to various applications depending on the activity performed by the robotic devices. There are robots that remove obstacles in pipes, perform prep work before the actual pipe restoration and reopen service pipes covered during the restoration. Experienced operators always control the crawlers from a special vehicle cabin.
Acceptance inspection of new piping
New sewers are always inspected upon completion in order to detect any hidden flaws and check all the factors that could determine the need for regular maintenance.
A sewer inspection should result in:
- an inspection report with an assessment in the official records – this includes the location of the defects identified, the scope of the defects, a record containing defect photographs, a pipe incline record, and an ovality measurement record.
- A recording of the entire inspection on a CD/DVD or a USB flash disk, with a description of the flaws in a browser program where a specific defect can be displayed.