Odour from Storm Ponds
Cause of the Odours
These odours are the result of naturally occurring compounds in the local soils and groundwater at YYC that infiltrate into stormwater ponds, wetlands and pipes where they undergo geochemical and biological reactions that produce odours. This is the same effect as what occurs with a sulphur spring, which can have strong sulphurous odours.
Odours vary in intensity based on weather conditions. Following recent studies of this issue by the University of Calgary and environmental engineering consultants, the following conditions were identified as producing strong odours:
- Odours most commonly occur early in the spring when ice is coming off the ponds. During the winter, there is no oxygen under the ice and this causes odour-generating compounds to be produced at a higher rate than during open water condition. Once the ice cover is gone and water is exposed to the atmosphere, odours will become present.
- Once the ponds are no longer ice-covered, hot and dry weather can accelerate production of the odours during the later spring and summer.
- Because the sulphur compounds can be denser than air, they often settle in low-lying areas (e.g., base of the hill beside Deerfoot City) when the air is cold and stagnant (i.e., overnight).
Due to the hot and dry conditions that occurred immediately following the winter this year (2023), odour management has been particularly challenging.