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

WW safety: practice questions

Our Water/Wastewater Operator bank has 11 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 Treatment Class I

Why must rotating equipment guards stay in place?

  1. To prevent clothing or body parts from being caught
  2. To hang tools
  3. They are optional
  4. To keep equipment warm and reduce noise for workers nearby
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A. To prevent clothing or body parts from being caught — Remove only under lockout/tagout.

Question 2 · Wastewater Treatment Class I

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

  1. Chlorine
  2. Methane from the digester
  3. Hydrogen sulfide
  4. Carbon dioxide
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C. Hydrogen sulfide — High levels deaden the sense of smell.

Question 3 · Wastewater Treatment Class I

What is required before entering a wet well classified as a permit-required confined space?

  1. Nothing if it's short
  2. A permit, atmospheric testing, ventilation as needed, an attendant and a rescue plan
  3. Only a coworker's OK
  4. Only a flashlight
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B. A permit, atmospheric testing, ventilation as needed, an attendant and a rescue plan — 29 CFR 1910.146.

Question 4 · Wastewater Treatment Class I

What is the upper atmospheric hazard limit for flammable gas in a confined space?

  1. 10% of the lower flammable limit (LFL)
  2. 100% of the LFL
  3. 50% of the LFL
  4. 50% of the lower flammable limit, measured at the top of the space
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A. 10% of the lower flammable limit (LFL) — 29 CFR 1910.146(b) hazardous atmosphere.

Question 5 · Wastewater Treatment Class I

Before working on a sludge pump, what must be done?

  1. Turn it off at the switch only
  2. Lock out and tag out all energy sources and relieve trapped pressure
  3. Ask someone to watch the breaker
  4. Nothing, if the job is short
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B. Lock out and tag out all energy sources and relieve trapped pressure — 29 CFR 1910.147.

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