Foul odour in Cochrane on Sunday caused by nearby accidental release of chemical additive

A foul stench that hit Cochrane on Sunday came from the accidental release of an odorant from a nearby gas plant.

Cochrane residents noticed a strong propane-like odour throughout the town and its surrounding area on Sunday. The town’s fire service received multiple complaints about the smell, and on Sunday afternoon the town confirmed the odour originated from a gas plant in the area that accidentally released mercaptan, which is also known as methanethiol.

The town added there was no active gas leak and no risk to public safety as of its Facebook post, which was posted to respond to local complaints, at 1:44 p.m. on Sunday.

"The issue has been resolved, and relevant agencies are aware and monitoring the situation. We appreciate residents bringing this to our attention and thank the community for their patience and vigilance," the town's statement on Facebook said.

Mercaptan is a substance added to natural gas to help identify any potential problems arising from the otherwise odorless and difficult-to-detect gas. Its odour is often described as similar to rotten eggs or cabbage, the town’s Facebook post said.

Kate McBride said she first noticed the what she thought was the strong smell of propane, when she let her dogs out on Sunday morning. She checked her house for leaks, and texted her neighbours who quickly confirmed they had noticed the same odour.

“It was alarmingly strong to the point where we were immediately concerned about where the source was. But it was almost nauseating,” says McBride.

After posting to local Facebook groups in Cochrane about the smell, McBride said the lack of information earlier in the day from the town was disruptive to residents. She was concerned when she didn't hear any information from the town or read any reports in the media about a gas leak on Sunday morning.

“It’s incredibly concerning to smell propane around your house and to not have any information at hand as we were discovering it," said McBride.

The odour disappeared by 7 p.m. on Sunday, McBride said.

The substance’s smell lingered longer than usual on Sunday, the Town of Cochrane said, because of changing weather conditions.