The City of Maryville has learned it must replace systems at its current wastewater plant even as it plans a full-scale replacement of the plant in the next 3-5 years. Funds for the upkeep work will come from reserves the city had saved to fund the future plant.
Speaking after a City Council meeting on Sept. 22, Manager Ryan Heiland explains there are 2 systems of concern. One is a membrane, which is the first part of the filtration process.
"When the raw water comes from Mozingo it enters the membrane,” he said. “It’s the initial process.”
One of those membranes is failing following a mechanical error that released an overload of chemicals into the system. The plant has 2 others which have taken over the process, Heiland says the system must be returned to full capacity to keep up with demand.
This is partially seasonal. "As we come into the winter months it gets harder to make water,” he said. “With these reduced-capacity membranes, if we have a large fire [in town, or] a large water main break, and that draws down our water towers, it’s going to be nearly impossible to make enough water to replenish those towers."
A replacement membrane will cost between $500,000 to $700,000.
City engineers have also voiced concern over the final piece in the process, the Granulated Activated Carbon.
“Just like your Brita Filter, it removes the taste and odor issues, and the water gets introduced into the system,” Heiland explained.
The lifespan of a filter depends on how hard it works. In recent winters, large algal blooms in Mozingo Lake have put significant stress on the filters. As winter approaches, Heiland explains it's best practice to have funds set aside to replenish the filter even if it ends up lasting longer.
“We can’t control what happens this winter,” he told councilmembers. “I’m bringing this up because we are putting funds in the 2026 budget, even though we hope that we won’t have to do anything until Fiscal Year ‘27.”
Between the membrane and the filter, the city is setting aside about $1 million for work at the plant next year. The money will come out of reserves the city had been hoping to use for a plant replacement.
But, says Heiland: “we can’t stop making water. So [this work is] unfortunately what we must do to make it through the next 3 years.”
The membrane systems will not carry over to the new plant. There will be some aspect of carbon filtration at the new facility, but as plans are not finalized it is unclear how and if the current systems will carry over.
