Welcome back to TPO magazine's Exam Study Guide Series, which offers a pair of water/wastewater study questions with in-depth explanations of the answers. Last time, we covered a set of wastewater and drinking water treatment questions on the topics of Wastewater Sampling and the Revised Total Coliform Rule. This time you can test your knowledge about permit-required confined spaces and fluoride concentration calculation.

Wastewater Treatment Sample Question

When defining confined spaces in your facility, who makes the determination whether the space is non-permit confined space or permit-required confined space?

A. OSHA
B. Local health department
C. Operator
D. Employer

Water Treatment Sample Question

The operator fed 10 pounds of H₂SiF₆ (25% commercial purity, 79.2% fluoride) into 600,000 gallons of water that contained 0.3 mg/L naturally occurring fluoride. How many pounds of fluoride did the operator add to the water and what should the finished water fluoride concentration be?

A. 10 pounds, 0.4 mg/L
B. 10 pounds, 0.7 mg/L
C. 7.92 pounds, 1.58 mg/L
D. 1.98 pounds, 0.7 mg/L

To see the answers to both the above questions, click this link.

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About the authors: Rick Lallish is the Water Pollution Control program director at the Environmental Resources Training Center (ERTC) of Southern Illinois University-Edwardsville. He provides training for entry-level operators in the wastewater field and operators throughout the state looking to further their education. Lallish was also named the 2017 Illinois Operator of the Year and 2018 president of the Illinois Association of Water Pollution Control Operators.

Drew Hoelscher is the program director of drinking water operations at the Environmental Resources Training Center in Edwardsville, Illinois.