Mona officials discuss sewer plant overflow, SCADA failures and plan for meter monitoring

Mona — City public works staff reported a sewer-plant incident in which a membrane element shut down, briefly flooding the plant interior but, according to staff, causing no state permit violation because the overflow remained on plant property.

At the council meeting staff described multiple compounding problems: a membrane shutdown that forced a backup unit offline, inconsistent SCADA (remote alarm) notifications that delayed awareness of the overflow for some callers, and recurring groundwater infiltration into the system. Staff said no equipment was irreparably damaged but acknowledged the plant's front door and property were exposed to process material during the event.

"It's not raw sewage," a staff member said during the discussion, explaining the material was activated sludge from the treatment process and that if discharges remain on plant property they do not automatically constitute a regulatory violation. Staff said the plant's alarm/SCADA system has been sporadic and has failed to notify operators reliably.

To better measure inflow and infiltration and identify sources, staff said the city would install temporary sewer flow meters in two manholes (one on an 8-inch line and one on a 15-inch line) and run them for about a week. The staff estimate used during the meeting for excess flow on paper was roughly 80,000 gallons, and a speaker said the temporary meters would cost about $300 to obtain. Staff also described plans to work with consultants Dan Feckner and Johnson Deville to isolate and quantify groundwater infiltration and to calculate treatment costs attributable to that infiltration.

Council and staff discussed public communication steps when the plant overflows, including the possibility of temporarily closing the green-waste site and placing signage if the plant is actively spilling onto access areas. Staff emphasized that if the discharge reaches waters of the state the situation would constitute a regulatory violation and require state notification; they said the recent incident did not meet that threshold because material remained on the plant property and was recaptured and re-treated.

Why it matters The discussion highlights operational limits at a small municipal treatment plant and the potential cost impact of treating groundwater and infiltration. Unreliable alarm notifications raise both operational and public-notice concerns; monitoring and corrective work may produce near-term repair and contracting costs.

What happens next Staff will install temporary meters, collect flow data, and follow up with a report and cost estimates for infiltration treatment. Staff also planned to coordinate with contracted technicians to troubleshoot a repeatedly tripping motor and improve remote alarm reliability.

Direct quotes in context - "It's not raw sewage. It's activated sludge," (staff member) said, describing the material that escaped into the plant interior. - "If it's inside the building, inside the property, then it doesn't really matter too much," (staff member) said, referring to regulatory exposure when discharge is contained on plant property.