Monroe City, Missouri

  • Population: 2,402
  • Employees: 6

THM Loses Battle with PeopleService
Monroe City Turns to PeopleService to Oust Carcinogen from Water

Situation Diagnosis

When PeopleService became Monroe City’s partner, we realized that some testing protocols were not as we prefer them. When we tested the water, we identified an issue with Trihalomethanes (THM). These are environmental pollutants and many are considered carcinogenic. They are formed when chlorine interacts with organic matter in water that is being treated. In other words, they are a disinfectant byproduct. There are permissible levels of THM allowed in the water that we watch for. That current permissible level of total THMs is 80 parts per billion in treated water.

When we noticed that Monroe City’s water was having trouble meeting this disinfectant byproduct rule, the city underwent a feasibility/engineering study to get to a long-term solution.


However, in the short-term PeopleService collaborated with the city’s engineers and the chemical company to devise a solution. After investigation, we realized that the secondary basin was feeding free chlorine causing the issue. We made the switch to chloride dioxide in the secondary basin to make the oxidation more stable, getting to the same result of disinfectant without the levels of THM we were experiencing.

Today, the THM levels have fallen below the thresholds they need to bring the city into compliance.

The POWER of PeopleService

Sometimes it’s good to have a new set of eyes and ears at your plant to apply years of experience to old ways of doing things – particularly if one or a few people have been running your plants. It didn’t take long for PeopleService’s tried and true testing procedures to unearth a potential issue for the citizens of Monroe City and curtail what could have been a disaster.

Water System

A 1.2 MGD conventional surface water treatment plant; and a water distribution system containing two elevated water storage tanks, mains of various sizes, valves and hydrants.

Wastewater System

The wastewater collection system consisting of various sizes of interceptor mains, manholes and including seven (7) lift stations; a wastewater treatment plant consisting of an influent pump station, bar screen, grit chamber, extended aeration, two (2) storm water overflow basins, a final clarifier, aerobic sludge digester, two (2) sludge storage basins. The sludge is land applied. Design flow of the treatment plant is 800,000 gallons per day with actual flows of 450,000 gallons per day. Sludge production is 144 dry tons per year.

To learn more about this case study and all the services PeopleService provides, talk to Chris McMillen at 877-774-4311 or

“PeopleService helped us get on track with compliance, and they’ve saved us a ton of money on chemicals and testing.”

– Chris Ellison
Interim City Manager
Monroe City, MO

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