The City of Chestermere, Alberta, has found success tackling long-standing hydrogen sulfide (H2S) issues by implementing a sidestream dissolved oxygen system, achieving both odor control and infrastructure protection at a fraction of previous costs.
Once a small commuter town of 5,000 residents, the city has grown to roughly 35,000 over the past two decades, straining the water infrastructure. The city relies on the nearby Calgary wastewater treatment facilities to treat its wastewater. But Calgary has strict H2S limits – an average of 5 parts per million (ppm) and a peak of 10 ppm.
“When I started in Chestermere, we were 5,000 people,” said Travis Arnold, lead hand at EPCOR Water Services, during a presentation at WEFTEC 2025. “Now we’re closer to 35,000 and with that growth has come our H2S issues.”
The city spent years trialing different odor-control methods. Sodium hypochlorite created safety concerns, while nitrate dosing worked but proved unsustainable – costing nearly $500,000 annually in chemicals.
In 2020, Chestermere conducted a feasibility study that identified sidestream oxygen injection as the most cost-effective solution. Following a pilot, the city commissioned a permanent supersaturated dissolved oxygen (SDOX) system at its main lift station in 2023.
Lift Station #13 (LS13) is the main lift station to Calgary. It has a 24 in. diameter and sends wastewater roughly 3.1 miles to Calgary.
Results since full implementation have been significant and include:
- Consistent compliance with Calgary’s discharge agreement
- Reliability of 96% uptime across more than 33,000 operating hours
- Operating costs were reduced by 90%, with a payback period of under 2 years
“With the system we have now, we’ve achieved better performance than any of the technologies we’ve used in the past,” said Alec Mackenzie, M. Eng., P. Eng., project manager at EPCOR Water Services.
Key lessons learned include the importance of proper system sizing, adjusting dosing seasonally and with daily loads, and investing in real-time monitoring. “Closing that feedback loop – from days to minutes – has had a substantial impact on our ability to control H2S,” Mackenzie said.
For Chestermere, proactive management and collaboration with technology providers have turned a persistent odor and corrosion problem into a sustainable success story.
