The Town of Monticello, Illinois operates a wastewater treatment facility serving a growing community in Piatt County. Like many small-to-midsize utilities, the team faced an elusive but critical challenge—detecting and responding to inflow and infiltration (I/I) impacts that don’t always show up during storm events. Light rainfall often felt like a non-threat to the collection and treatment system, but saturated ground conditions were still contributing to hidden surges in influent flow.

Without real-time insights or predictive context, Monticello’s team couldn’t confidently make early operational decisions—until now.

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Challenge

The facility needed a way to distinguish between routine operational changes and environmentally driven I/I activity, especially during periods of light or intermittent rain. These low-visibility events, particularly after multi-day ground saturation, were leading to unnoticed increases in flow and stress on the system. The plant lacked an efficient way to detect these signals in advance and adjust processes accordingly.

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Solution

Aquaspec deployed a comprehensive data readiness assessment and I/I intelligence model using 3.28 years of flow, operations, and water quality data from the Monticello WWTP. With daily flow data over 99.8% complete and near-perfect temporal consistency, the team was able to map baseline diurnal flow profiles and detect non-obvious I/I contributions associated with:

• Light rainfall following periods of high soil saturation;  

• Off-hour (early morning) surges not aligned with normal usage patterns; and  

• Day-to-day increases in base flow not linked to population-driven demand.

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These insights allowed the Monticello team to operationalize earlier, adjusting staffing, aeration, creating capacity in surge tanks and lift stations, and optimize holding strategies based on real-world predictive signals, not weather assumptions.

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Results

The impact was clear and operationally transformative:

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• Hidden I/I events detected even during light rain (<0.25”) following multi-day wet soil periods;  

• Earlier operational adjustments initiated hours before peak influent volumes, improving process control and COMPLETELY PREVENTING combined sewer overflow (CSO) events; and

• Flow forecasts identified threatening conditions up to 12–18 hours before traditional indicators showed stress;  

• Reduced risk of expensive process upsets and permit excursions, especially during seasonal wet periods

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“We used to wait and see. Now we move early, even before the rain gauge says we should. That’s the difference.”

— Matt Utley, Wastewater Superintendent, Town of Monticello WWTP

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Outcome

Monticello’s team is now operating on foresight, not just hindsight. By leveraging high-readiness flow data and applying it to I/I behavior, they’ve gained the power to act before the system shows stress. This approach gives small utilities the tools to compete with the responsiveness of much larger systems—without the cost.

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This is what modern wastewater operations look like: data-driven, environmentally tuned, and always one step ahead of the threat.

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