TECHNICAL FEATURES
Sewer maintenance: myth busting and best practice
Sewer maintenance is an ongoing challenge for cities and municipalities. Moreover, gaps in best practice training can cost public works departnents unnecessary time and expense in labor, water, and energy costs when cleaning sewer lines.
Making matters worse, our comprehension of sewer line cleaning has evolved alongside the advancements in hose nozzle technologies, which in some cases directly contradicts current practices. So, when conducting training classes across North America, Dan Story, an Operations Manager and national trainer at KEG Technologies, first addresses a common misconception. Many have been trained to quickly run sewer line hoses up the line to effectively remove debris. However, this “hurry up and clean” approach is counterproductive and can potentially redirect sewage flow into homes, commonly known as “blown toilets.”
“For years, sewer maintenance crews have been taught to shoot a nozzle up a line in a hurry and clean as they come back,” says Story, whose company provides Tier 1 to Tier 3 nozzles, chain cutters, floor cleaners and camera nozzle systems to the industry. “But this is not a race. If you are not slowing down to cover all the ground, it simply is not going to work very well.”
Instead Story trains sewer crews to “clean as you go in and rinse as you come out,” adds Story. “With this approach, 95% of the time you will clean a line in one pass instead of making a whole lot of passes.”
For Story, who travels across the United States and Canada conducting training on sewer cleaning techniques, misconceptions
abound in the industry and often reflect a lack of understanding of the fluid dynamics of high pressure nozzles. Over time, additional best practices have been developed through a process of trial and error.
As part of his training sessions, Story provides the following additional tips for sewage line cleaning:
“Read” the results
Story says you can learn a lot by paying attention to what is happening in the line going in and coming back.
“Crews need to be trained to understand what they are ‘reading’ coming out of the pipe. The information can tell you whether you are going too fast or too slow, how much debris is in the line, and whether the line is clean after the first pass – or not,” says Story.
When going up the line, for example, it is beneficial to observe the amount of debris present.
“If there is minimal debris returning, it indicates that the pipe is in relatively good condition, with a low accumulation of debris. So, I can accelerate my speed. However, an excessive amount of recovered material suggests the need to slow down. In such cases, the flow of water acts as a conveyor belt, effectively carrying the debris out.”
When the water flow confirms the pipe has been cleaned at the right speed, the maintenance crew can then lower the pressure in the hose to between 900 – 1,000 PSI and come back through the pipe at the same speed. This final single “rinsing” pass can leave the line totally clean.
“The trick is paying attention to your hose. Make sure your hose comes back clean, and then you know your pipe is clean. How much debris is in the first pass? This information can tell you whether you’re going too fast or too slow. Remember to never outrun your flow because your flow is your conveyor belt. If there is a lot of material on the hose, it is telling me to slow down. If my hose stays clean, I know I am moving at a good pace,” says Story.
Another common sewer cleaning misconception is that you don’t need to open the upstream manhole when cleaning sewer pipes. This can actually increase pressure in the system and lead to blown toilets, where sewer gases flow up the laterals and cause sewage water to overflow from residential toilets.
According to Story, approximately 95% of blown toilets can be attributed to how the operator cleans the lines. However,
46 | February 2024 |
www.draintraderltd.com
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