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Career spotlight Grade 7 Careers & CTE

The Technician Who Runs Halvergate's PFAS Filters

A grade 7 spotlight on a treatment technician who operates carbon filter vessels for PFAS in the town of Halvergate, with percent-removal questions and a licensing path.

Objectives

  1. Students will describe the daily work of a technician who operates carbon treatment vessels.
  2. Students will describe how a state water operator license is earned and how an operator moves up in class.
  3. Students will calculate percent removal and percent increase from plant operating data.

Vocabulary

PFAS
A large family of human-made chemicals used in things like nonstick pans, waterproof fabric, and firefighting foam. They are called forever chemicals because they take a very long time to break down.
Granular activated carbon
Small black grains of specially treated carbon that grab contaminants as water flows through them. Utilities use big tanks of it to remove PFAS, bad tastes, and odors.
Parts per trillion
A unit for measuring extremely small amounts of a chemical in water. PFAS limits are set in parts per trillion because these chemicals matter even in tiny doses.

Also: vessel, operator license

Teacher overview

PFAS are a family of manufactured chemicals that break down very slowly, and several of them are now regulated in drinking water. Systems that find them often add tall steel vessels packed with treated carbon, and someone has to run those vessels every day. This profile follows one licensed technician through a shift at a plant in the fictional town of Halvergate. Students often assume a treatment plant removes every substance from water at once, so the profile makes clear that each barrier handles a different problem and that carbon vessels were added for one specific job.

The Technician Who Runs Halvergate's PFAS Filters — Grade 7 Careers & CTE
Name: ____________________________ Date: ______________

Career Profile

What the job looks like. Devon Yeatman is a water treatment plant operator in the town of Halvergate. Most of his shift belongs to four carbon vessels that stand outside the main building. Each vessel is packed with granular activated carbon, which is a black grain with a huge amount of surface area inside it. Water flows down through the grains. PFAS molecules stick to the carbon and stay there while the water keeps going.

Devon starts by reading the pressure on each vessel. A rising pressure difference means the bed is clogging. He walks the pipe gallery and listens to the pumps. Then he draws samples from three points, one before the vessels, one between the two stages, and one after. The samples go to a lab, because PFAS are measured in parts per trillion and no plant can test for them at the sink. He logs the flow through each vessel and compares it to yesterday. When the lab reports show PFAS reaching the middle sampling point, the lead vessel is spent and the carbon must be replaced.

The rules he works under are still in motion. The federal limit for PFOA and for PFOS is 4.0 parts per trillion each, set in April 2024. Systems must meet it by April 2029. In May 2026 the EPA proposed letting eligible systems apply for a two-year exemption, to April 2031, but that proposal was not final as of September 2026 and would not change the limit. Devon follows the rule as written and keeps records that show what his plant did and when.

Getting the license. Devon finished high school and worked two summers on a utility maintenance crew. He then trained under licensed operators while studying for the state exam. A high school diploma, on-the-job training, and a state license earned by exam are the usual entry path. Licenses run in classes tied to plant size and to years of experience, so an operator moves up by testing again. Devon is now taking community college chemistry, because he wants the license class that allows him to run a larger plant.

Pay and outlook. Water and wastewater treatment plant operators earned a median of $60,020 per year in May 2025. The lowest tenth earned less than $39,110 and the highest tenth earned more than $91,060. The Bureau of Labor Statistics projects about 10,000 openings each year from 2025 to 2035 for operators specifically, and all of them come from replacing workers who retire or change careers rather than from new positions. Licensing is one way into water work. Community college certificates, four-year engineering degrees, and graduate study in environmental science lead to other roles at the same plant.

Student Handout

Suppose the town of Halvergate runs the carbon treatment plant described above. Each question gives you the numbers you need.

  1. Name two tasks Devon does during a shift.
  2. In your own words, explain what the carbon inside a vessel does to PFAS.
  3. Water entering the vessels tests at 24 parts per trillion of one PFAS chemical, and water leaving tests at 3 parts per trillion. What percent of that chemical was removed?
  4. The federal limit for PFOA is 4.0 parts per trillion. Is a result of 3 parts per trillion above or below that limit?
  5. The plant treats 1.2 million gallons on an average day, and the carbon must be replaced after 900 million gallons pass through. About how many days does one load of carbon last?
  6. Halvergate added 2 new positions to a plant staff of 16. What was the percent increase in staff?
  7. Halvergate could have drilled a new well instead of adding carbon vessels. Name one benefit of the carbon vessels for water customers.
  8. Name one cost of the carbon vessels for the people who pay water bills.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: Any two of these tasks. Devon reads the pressure on each vessel, walks the pipe gallery and listens to the pumps, draws samples at three points, logs the flow through each vessel, compares today's flow to yesterday's, or calls for a carbon change when the lab reports show PFAS at the middle sampling point.
  2. Answer: The carbon holds the PFAS. Water passes through the grains while the PFAS molecules stick to the huge surface area inside the carbon and stay behind.
  3. Answer: 87.5 percent. The drop is 24 minus 3, which is 21. Divide 21 by the starting value of 24 to get 0.875, then multiply by 100.
  4. Answer: Below the limit. A result of 3 is less than the limit of 4.0.
  5. Answer: 750 days. Divide 900 million gallons by 1.2 million gallons per day to get 750.
  6. Answer: 12.5 percent. Divide 2 new positions by the starting staff of 16 to get 0.125, then multiply by 100. Students who divide by 18 have used the ending staff instead of the starting staff.
  7. Answer: Accept any reasonable benefit. Sample response: the vessels treat the water the town already pumps, so customers keep the same source and get water with much less PFAS in it.
  8. Answer: Accept any reasonable cost. Sample response: the carbon has to be replaced again and again, and the cost of that work reaches customers through their water bills.

Differentiation

Support

Give students a labeled cross-section of a carbon vessel with arrows for water in, carbon bed, and water out before they read. For question 3, provide the subtraction step already done, so students begin from the value 21 and focus on choosing the correct starting value for the division. Allow question 5 to be checked with a calculator.

Extension

Ask students to write the short daily log entry Devon would file on a day when the middle sampling point first shows PFAS. The entry must state what the reading means, what action it triggers, and which record a state inspector would want to see. Students should use only information from the profile.

ELL supports

Pre-teach "vessel," "carbon," and "parts per trillion" with a simple picture and a familiar comparison for very small amounts, such as a few grains in a very large jar. Allow questions 1, 2, 7, and 8 to be answered in short phrases. Provide a sentence frame for question 4, such as "The result is ____ the limit because ____."

Extensions

Have students research which barriers a plant uses for other problems, working only from the list of stages named in class, then build a labeled flow diagram that places the carbon vessels in order with the other steps. A closing discussion can compare what each stage is good at and why no single barrier handles everything.