Sour gas rupture in flooded southern Alberta causes evacuations

Canmore flooding
Several communities in Southern Alberta are under a state of emergency after recent rainfall, forcing evacuations over worries of flooding. Sarah Offin/Global News

TURNER VALLEY, Alta. – A leak of potentially deadly sour gas in a southern Alberta town that also faced flooding caused evacuations and confined other residents to their homes on Thursday.

“The town of Turner Valley has evacuated some residents and has put others under shelter-in-place as a precautionary measure,” said Cara Tobin of the Alberta Energy Regulator.

About 150 people were forced to leave the town of about 2,500, said RCMP Sgt. Patricia Neely.

Read more: Rainfall sparks State of Emergency in Southern Alberta communities

The leak was at the south end of the community and in an exposed section of pipe running from a wellhead. The pipe is owned by Calgary-based Legacy Oil and Gas. Tobin said the leaking gas is about one per cent hydrogen sulphide.

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“Any amount of hydrogen sulphide is a concern,” said Tobin, who added the pipeline’s owners has air monitors at the scene.

“The company hasn’t detected any dangerous levels of H2S at the break point, but our air monitoring unit is on site and will confirm that data.”

An Alberta Emergency Alert was issued Thursday morning indicating a pipeline had ruptured in the community.

The alert called the rupture potentially life-threatening and urged people to move indoors and prepare for a possible evacuation.

Sour gas is colourless, natural gas that smells like rotten eggs. It contains hydrogen sulphide and is extremely toxic even in small amounts.

The Canadian Association of Petroleum Producers says about 30 per cent of natural gas in Western Canada is sour and some crude oil produced in the region is also sour.