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Water & Wastewater Operator (WPI/ABC Class I) — Practice Exam

WC safety: practice questions

Our Water/Wastewater Operator bank has 12 questions on this topic. Here are 5 of them with answers; the full mock exam draws from every topic, like the real one.

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Question 1 · Wastewater Collection Class I

Before working on a lift station pump, what must be done?

  1. Turn it off at the panel only and start work
  2. Ask someone to watch the switch
  3. Lock out and tag out power and isolate the pump from the wet well and force main
  4. Turn it off at the control panel only and start work while a coworker watches the switch
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C. Lock out and tag out power and isolate the pump from the wet well and force main — 29 CFR 1910.147.

Question 2 · Wastewater Collection Class I

Why is forced-air ventilation used before and during manhole entry?

  1. To cool the wastewater and dry the pipe walls
  2. To dry the pipe
  3. To push odors into nearby homes
  4. To dilute and remove hazardous gases and supply fresh air
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D. To dilute and remove hazardous gases and supply fresh air — Continue testing during entry.

Question 3 · Wastewater Collection Class I

What PPE is important when operating a high-pressure jetter?

  1. Eye and face protection, gloves and hearing protection
  2. Only a hat and boots, since water pressure is low
  3. No PPE
  4. A respirator only
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A. Eye and face protection, gloves and hearing protection — High-pressure water can cause serious injury.

Question 4 · Wastewater Collection Class I

How deep can a trench be before OSHA generally requires a protective system?

  1. 2 feet
  2. 5 feet
  3. 10 feet
  4. 20 feet
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B. 5 feet — Unless in stable rock; 1926.652.

Question 5 · Wastewater Collection Class I

Which gas in sewers smells like rotten eggs and can be deadly?

  1. Nitrogen
  2. Carbon dioxide
  3. Methane produced by decomposing sludge in the sewer
  4. Hydrogen sulfide
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D. Hydrogen sulfide — It deadens the sense of smell at high levels.

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