Esme Wilson, a district staff member, told the Francis Howell School District Board of Education on July 17 that air monitors placed at Renaissance North have not detected hazardous gases and that recent engineering data points to pressure in the municipal sewer system as the most likely source of intermittent sewer odors in the building.

Wilson said the district has operated 10 air monitors for months and “they still have not read any, any dangerous elements in the building.” She reported occasional VOCs traced to janitorial waxing and propane-powered scrubbers, and said hydrogen sulfide and methane (LEL) readings have not been recorded.

The district also repaired roughly three minor plumbing breaks identified by smoke testing and re-tested the piping; the repairs eliminated any open plumbing pathways from the building interior, Wilson said. Engineers then installed manometers on five rooftop plumbing vents and recorded pressure readings at 10-second intervals for 10 days, producing about 87,000 data points. The highest recorded rooftop pressure was 0.10 inches of water column; Wilson said readings of 0.05 inches are comparable to the positive‑pressure standard used to protect immunocompromised hospital patients.

Those positive pressure spikes appeared both when the building was occupied and when it was empty, Wilson said, including overnight and on weekends. The pattern led engineers to suspect the source is not on-site activity but pressure transmitted back through the municipal sewer system. Wilson said the district has asked the municipality for information and that the next step is to place a manometer in the sewer main manhole to compare main-line pressure with the building readings.

Why it matters: if municipal sewer pressure is forcing positive pressure into the building’s plumbing vents, small plumbing breaks — which would normally be contained — can emit noticeable sewer gas into occupied spaces when the system is under positive pressure. That dynamic, Wilson said, explains sudden, short-lived odor events reported by staff.

What the district will do next: Wilson said engineers from McClure Engineering and Bax Engineering are developing options that aim to isolate the building from the sewer‑main pressure before it reaches the structure. Possible fixes discussed include installing a relief or trap in the sewer main upstream of the building connection; the engineers also prepared rooftop vent relocation drawings that remain under price solicitation from subcontractors. Wilson said addressing the municipal-pressure problem would be less costly and less disruptive than extensive rooftop piping relocations, and would avoid the long appliance of horizontal runs across the roof.

Timing and safety: Wilson said manhole monitoring in the sewer main will proceed over an upcoming weekend and that engineers expect to identify a technical fix in the following weeks. She added that because the district has capped roof vents and repaired the interior plumbing breaks, staff do not expect a recurrence of noticeable odors when students return in August, though an upstream repair before the first day is not guaranteed.

Questions at the meeting addressed feasibility and cost: a board member asked whether the building could be reconnected to a different sewer branch; Wilson said gravity and existing elevations make that approach impractical. Another board member asked who would pay for remediation; Wilson said that decision is under discussion with district counsel and the municipality.

Ending: District staff said monitoring will continue while engineering refines the preferred solution and seeks municipal coordination. The board received the update and had questions; no formal vote was taken on the technical work at the July 17 meeting.