Identify deficiencies that may impact IEQ and/or sources of odor concerns. Typically includes the following depending on the nature of concern, but not limited to:
- interview/questionnaire of concern individual(s)
- inspection above drop ceiling (condition of roof deck, pipe insulation, return air plenum)
- inspection of ventilation system (operation of variable air volume box and outdoor air dampers, check controls, measurements of carbon dioxide, temperature and relative humidity, sources near outdoor air intake, measure return and supply air volume, cleanliness of coils, liner and condensate pan)
- inspection of exterior
- inspection below drop ceiling (housekeeping, sink and floor drain traps, signs of past and present moisture concern via visual and/or moisture meter, mold growth, ensure connection of current and capping of abandoned sanitary vents, odorizers, excessive plants and fabric items, identify potential pathways, and measure volatile organic compounds, carbon monoxide, and lighting)
Date(s) of Assessment: November 21 and 22, 2019
Custodial staff reported that a Building Services (HVAC) contractor had drained the hot water line of the boilers as part of a recent boiler replacement project.
A floor drain clogged during the draining process and flooded a portion of the boiler room (concrete floor).
A strong chemical odor then reportedly diffused into the classrooms above the boiler room. It was reported by Administration that students were moved from the areas impacted by the odor. Windows were opened to increase dilution.
By the time the Office of the Environment arrived onsite, the source of the release had been contained by closing the purge valve and the flooded water had been cleaned up. It was reported that the odor had significantly dissipated when the Office of the Environment arrived. The odor was described as "sweet" and/or "antifreeze."
No apparent odors were sensed within the boiler room or school upon the Office of the Environment's arrival.
It was reported that the chiller (not the boilers) had recently been injected with propylene glycol to prepare for the heating season. Each of these systems is a closed-loop. Water from the chiller mechanical systems would not be expected to get into the boiler mechanical systems (and vice-versa) as the piping is not physically connected.
A refractometer was used to determine if glycol had somehow gotten into the hot water line of the boilers. No glycols were detected.
A boiler outlet valve was opened so that the Office of the Environment could smell the odor that was reported. An odor was detected in the discharge. The custodian confirmed this was the odor of concern.
Buildings Services water treatment contractor indicated that there is a water treatment chemical in the boiler system (Formula 200). The boiler system is not the drinking water system. The product data sheet indicates that the chemical does not have an odor. The Office of the Environment met the water treatment contractor onsite. Both the dry chemical and the diluted chemical (unused) were smelled. No odor was present.
The Office of the Environment collected a water sample from the boiler (closed-loop) and measured the head-space of the sample with a photo-ionization detector. Volatile Organic Compounds (VOCs) were detected in the head-space of the sample.
Laboratory Analyses
A sample of the water was collected and taken to a laboratory for headspace analysis to determine the VOCs that may be causing the odor.
- Various VOCs were detected in the analyses.
- The laboratory indicated the VOCs detected were likely byproducts from the manufacture/installation of the boilers.
The water was also analyzed for glycols as laboratory analyses would be more sensitive than the refractometer testing noted above.
- Ethylene glycol was not detected in the sample.
- Propylene glycol was detected in the sample at a very low concentration.
A bacteria sample was also collected from the boiler mechanical system by Building Services water treatment contractor. Bacteria and associated metabolites/byproducts can cause odors in water systems.
- No bacteria was detected within in the sample.
Conclusion
Various VOCs were detected in the water sample. The origin of many of the VOCs was likely associated with the manufacturing and installation of the new boilers and is likely typical. Propylene glycol was also present in the sample, however this constituent was not anticipated to be in the boiler system. Building Services is not aware how propylene glycol was introduced into the system. A release such as this is not anticipated to occur during normal operating conditions because the boiler loop is typically closed. The release occurred because a contractor purged the system for maintenance and the floor-drain clogged.
In general, symptoms of short-term VOC exposure typically reside when removed from the impacted area and brought to fresh air/away from the source.
Signage was placed on the boiler room door stating that boiler water is not to be discharged.
The boiler will be fully drained in the spring prior to switching the system over to cooling mode. The system will then be refilled and treated with a food grade treatment product. The odor is not expected to return as the system does not need to be drained for any future work.
A Building Services contractor cleared the floor drain.