It's not unusual for problems to arise from deteriorating manholes. With time, manholes may develop structural damages like cracks and fractures, resulting in decreased capacity, excess treatment costs, and increased risk of overflow to the sewer system or clean water sources. Besides, manholes are the first access points to any underground sewer system. That is why developing an inspection process with regular condition assessments is a critical aspect of every sewer system maintenance program.
Manhole Inspections can be a component of overall sewer line inspections, where video inspections (CCTV) are used to inspect storm sewers and/or sanitary sewer lines.
Why are Manhole Inspections so Important?
First, a sewer system inspection should be considered complete only if everything, including the manholes, have been repaired as per the specifications. That can help enhance efficiency and cost-effectiveness. The purpose of manhole inspections is to evaluate and identify various defects.
Moreover, the inspection company should follow the sewer inspection regulatory authority guidelines to ensure a quality inspection. The authority has also created a set of rules to ensure utility owners' needs are met through its certification program for manhole assessment.
The first level of these rules requires an inspection to provide a critical evaluation report regarding the overall condition of the manhole. The second level gathers detailed data that outlines the damages, the actual state of the manhole and recommends an action plan.
Common Manhole Inspection Problems
Below is a list of the four most essential manhole inspection items to consider when conducting a sewer inspection.
• Manhole Chimney
The manhole chimney is the most critical item to examine during the inspection. The chimney may appear perfectly fine during the dry weather, but that might not be the case during heavy rains or when the groundwater is at its peak. Heavy rains or deterioration of the manhole chimney can also cause clogs and blockages.
• Rubber Boot
During the construction of a new manhole, a rubber boot is installed on the slab to facilitate the installation of sewer pipes. The rubber boot is firmly tightened with bands to create a watertight seal. In some cases, concrete is poured around the tube instead of the boot, and this can potentially cause infiltration.
• Correct Stacking
During the construction of sewer systems, everything must be appropriately stacked out to avoid hazardous situations. Usually, most municipalities and utilities provide specifications and a set of detailed plans to be followed during installation. But for some reason, these guidelines are not always observed, resulting in shoddy work.
• Inspect for Surcharging
During heavy rains, surcharging can occur and obstruct the sewer. It would therefore help if you checked the sewer system after heavy rain. It also helps to have the sewer laterals connected directly to the central system (the mainline) rather than to the manhole.
The Bottom Line for Manhole Inspections
Manhole inspections are indeed essential aspects of any functioning sanitary sewer system. Overlooking manhole damages can cause severe issues in the future. Therefore, the municipalities and utilities looking to inspect their manholes should find qualified and experienced contractors to handle the job.
GPRS is proud to be a member of the National Association of Sewer Service Companies (NASSCO) and participates in all certification programs.