Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

25 Ways to Screw Up a Lift Station Design - v.20

One way to think about engineering is to consider it the organized study (and avoidance) of failure Here are 25 different failures (plus a few bonuses) to avoid on your next lift station project, whether it's a clean-sheet design, a retrofit, or a rehabilitation. Avoiding these mistakes will improve safety, performance, and maintenance-friendliness.

  • Be the first to comment

  • Be the first to like this

25 Ways to Screw Up a Lift Station Design - v.20

  1. 1. 25 Ways to Screw Up a Lift Station Design Brian Gongol DJ Gongol & Associates, Inc. March 31, 2021 Iowa WEA Region V Spring Meeting Huxley, Iowa
  2. 2. Don't make the same mistakes twice We're very good at ignorance-removal, and fortunately for us, we have a lot more ignorance to remove." - Charlie Munger
  3. 3. 1. Omitting toxic-gas detection
  4. 4. The risks get bigger as you go deeper
  5. 5. Low-cost gas monitors can be lifesavers
  6. 6. 2. Cramping pumps, valves, and people
  7. 7. It won't work if nobody can work on it
  8. 8. The ideal: Room for people, tools, and parts
  9. 9. 3. Permitting wetwell air entrainment
  10. 10. A pump is not a fan, but air will butt in first
  11. 11. See it happen
  12. 12. Use baffles and diameter effectively
  13. 13. 4. Vortexing
  14. 14. A magical sight, but not helpful
  15. 15. Want to see it happen?
  16. 16. Set low water levels safely above pump inlets  Flow and inlet diameter determine inlet velocity  Velocity determines required submergence  If you can't add more depth, widen the inlet  Velocity (in fps) = GPM x 0.41 / (diameter2 )  Refer to published submergence charts  At 200 gpm: 4" - 5.125 fps, 3.0' submergence 6" - 2.278 fps, 1.5' submergence
  17. 17. 5. Cascading inlets onto the pumps
  18. 18. Locate pumps carefully or use pipes, baffles
  19. 19. 6. Locating a VFD 75' or more from the motor
  20. 20. Bouncing back
  21. 21. Reflected waves can mess up a motor
  22. 22. 7. Using a VFD where static head prevails
  23. 23. Which is the better VFD candidate?
  24. 24. If it doesn't add value, take it out
  25. 25. 8. Overlooking a soft starter
  26. 26. Sometimes motors just need a gentle nudge
  27. 27. 9. Turning piping into a spaghetti bowl
  28. 28. Simplify until you can't anymore
  29. 29. 10. Under-sizing the wetwell
  30. 30. Bigger wetwells are a gold mine  Guarantees future capacity  Adds safety factor to your emergency-response time  Insures against backups and basement flooding  Facilitates better equipment spacing  Reduces frequency of motor starts  Note: If slow turnover is a concern, septic issues can be addressed with small mixing and/or aeration systems
  31. 31. 11. Not accounting for maintenance
  32. 32. Stations need tools, space, and trained people
  33. 33. What have we learned from the pandemic? "Social distancing" requires us to demand safe, roomy working conditions
  34. 34. 12. Omitting valves for air and vacuum
  35. 35. High points, local high points, and long runs
  36. 36. Remember: Your pipes are like you If your pipes can't breathe, they might collapse
  37. 37. 13. Failing to provide adequate heat
  38. 38. Below ground or above, stations need heat
  39. 39. 14. Failing to provide adequate cooling
  40. 40. Motors, controls, and people need cooling
  41. 41. 15. Omitting gauges
  42. 42. Nothing is a better for seeing deep inside
  43. 43. Don't go without gauges A pump system without gauges is like a doctor without a stethoscope
  44. 44. 16. Cutting solids passage too small
  45. 45. Residents aren't becoming more careful
  46. 46. Stringy solids + FOG = Headaches
  47. 47. 17. Skipping NPSH calculations
  48. 48. Always calculate NPSH, even for submersibles
  49. 49. NPSH is the root cause of many problems Those problems do not go away just because the pump is hidden underwater
  50. 50. 18. Not planning for clogs
  51. 51. This too, must pass: Even a rubber chicken
  52. 52. Want to see it?
  53. 53. Even if you got rid of wipes... Clogging issues are only going to get worse as household and commercial users behave more efficiently
  54. 54. Dishwashers, clothes washers, showerheads...
  55. 55. 19. Misaligning equipment to staff capacity
  56. 56. If you break it, you ought to be able to fix it
  57. 57. You need to be able to fix things yourself You can't predict when:  Mar 2021 | A ship will get stuck and block the Suez Canal  Feb 2021 | A freak winter storm will shut down Texas  Aug 2020 | Rolling blackouts will close California  June 2020 | China will run out of shipping containers  Mar 2020 | States will mandate two-week quarantines on interstate travel
  58. 58. 20. Under-sizing motors
  59. 59. Size the motor for the far-right
  60. 60. 21. Failing to calculate future head curves
  61. 61. Your system will change, so be ready
  62. 62. 22. Fixating on limited backup options
  63. 63. Consider all the choices
  64. 64. Backup power isn't a stand-alone luxury You need backup power when something else is already going wrong
  65. 65. 23. Cutting corners on material quality
  66. 66. Aim for long-term maintenance
  67. 67. Amortize costs of better equipment into capex Lots of factors count:  Hardness  Ductility  Tensile strength  Corrosion resistance
  68. 68. 24. Designing a second-class workspace
  69. 69. Clean, safe workplaces matter
  70. 70. 25. Going underground without need
  71. 71. Put nothing underground that could go above
  72. 72. Bonus Round  Not conducting a surge analysis  Failing to plan for grit and solids buildup  Choosing the wrong voltage  Putting safety second  Skipping a system test  Failing to account for water volumes in sewer lines  Failing to account for water volumes in force mains
  73. 73. Above all... Engineering is the study (and avoidance) of failure... so pay attention to the mistakes around you. And then don't make them.
  74. 74. Questions?  Thank you for your attention  Do not hesitate to follow up with questions anytime (no obligation!)  Brian Gongol DJ Gongol & Associates  515-223-4144  info@gongol.net  @djgongol on Twitter, Facebook, and Instagram
  75. 75. Sources and References  Photo of Dwight Eisenhower in uniform from US Army collection is in the public domain  http://www.loc.gov/pictures/item/2009634158/  Photo of blimp over the Lincoln Memorial is in the public domain  http://www.loc.gov/pictures/item/2016889614/  Reflected wave phenomenon article screenshot from Eaton:  http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/ thereflectivewavephenomena.pdf  NPSH formula taken from "Selection and Application of Self-Priming Centrifugal Pumps", courtesy of the Gorman-Rupp Company  Dishwasher manual screenshot is from the Kitchen Aid KDTE254ESS1  Pump curve courtesy of the Gorman-Rupp Company  Image showing three lift station types courtesy of the Gorman-Rupp Company  All other photos and illustrations are the original work of Brian Gongol and all rights are reserved

×