Minimizing Sanitary Collection System Overflows

Here are methods suggested to prevent overflows from sanitary collection systems. Some may not work, some are intended for humor only.

  1. Regular cleaning of sewer lines.
  2. Preventive maintenance cleaning of troublesome sewer mains.
  3. Pumps, barriers to keep overflowing liquid out of waterways.
  4. First you need to determine when overflows are occurring. Do they occur during rains? If so you may have a serious infiltration or inflow problem that needs to be corrected. If the overflows occur near creeks, perhaps there is a break in the line that needs to be repaired or one or more manhole covers off.
  5. If overflows occur during dry periods, then you may have an overloaded sewer and a relief line may be the answer.
  6. Preventative maintenance of the lines to maximize the capacity is always best. Perhaps installing water tight lids would help, provided such action would not cause the backup into a basement.
  7. Conduct an I&I survey to see where your flow is coming from and then perhaps perform a pipe lining or other suitable technique for elimination of this.
  8. Use manhole covers to buffer the inflow into the manholes.
  9. Install some type of holding tank/pump station as a temporary solution. But eventually population growth would overcome this.
  10. Using pipe bursting equipment or other means, install larger interceptor and/or lateral lines.
  11. Proper design sizing and slope of pipes.
  12. Selection of good quality manholes, lids. etc. and good quality, factory tested pipes with good quality joining systems (while problems with pipe breakage or collapse, infiltration and/or exfiltration from pipes or joints, are obvious, problems can also be caused by later root intrusion, etc. in poor quality pipe or joints as well)
  13. Well designed and effective pipe/structure/manhole and service penetrations.
  14. Effective installation, inspection, and acceptance testing of the pipeline, etc. with available resources in the construction phase.
  15. Go leak hunting in the wet season and patch leaks.
  16. Go house to house and get rid of all the sump pump connections.
  17. Smoke test in the summer.
  18. Feed long chain polymers about 20 minutes upstream of the overflow. If you get the dosage right, you can increase pipe capacity by about 30%. [untested in field conditions]
  19. Bolt the manhole covers shut and store the water in people's basements.
  20. look for areas where "kids take the covers off". My experience is that kids don't often do this.....surcharged flow does! I have seen sewage flowing out of the top of a manhole such that the lid was suspended 8 inches [20 cm.] above the fountain of sewage and spinning slowly around.
  21. Pull lids in wet raining weather...amazing what the sewers will show prepared to get very wet and work evening is well worth it.
  22. I agree with the water tight lids. I have seen many sanitary sewers acting as surface effect storm sewers.
  23. Do some flow monitoring....branch help define areas that may be suspect. In every sewer system I have worked on, we have found "Big Boys"...those locations where a little $$ saves a lot of flow.
  24. How about dissuading people from putting in stuff that is likely to cause a blockage or reduction in capacity. Like building materials, grease, large solids etc.
  25. Better management and control of pumping stations may be important, depending on your system.

These ideas originally were posted on the SEWER-LIST mailing list.
Contributors: Randy Connor, Eric Greenberg, Alan VanDeBoe, Jerry Haimowitz, Doug Uhren, Martin Osborne, Miles Abernathy. Return to the SwopNet Engineering Databank