The Alliance Pipeline website is seen in this file photo.
A natural gas pipeline that extends from northeastern British Columbia to the Chicago area has been shut in order to dispose of dangerous hydrogen sulphide gas that got into the system.
Alliance Pipeline said it expects its mainline to be closed for an "indeterminate amount of time" as it deals with the gas, which is poisonous, corrosive, flammable and smells like rotten eggs. The company did not say how much of it entered the pipeline.
Alliance said it plans to burn off the gas within the confines of its Alameda compressor station about 250 kilometres southeast of Regina, and that there is no risk to human health and no expected environmental harm.
"Our chief concern now is to ensure the safety of the public, employees and the environment. We are working to remove the H2S from the pipeline in a controlled and safe manner," said Alliance vice-president Daniel Sutherland in a news release late Thursday.
"We apologize for any inconvenience this may cause to our customers and we are working with our partners and the regulator to determine the cause."
Alliance said the incident was the result of "complications experienced by an upstream operator," but did not identify the company involved.
However, natural gas processor and transporter Keyera Corp. said in a statement Friday that there was a "brief operational upset" at its Simonette gas plant in northwestern Alberta on Wednesday. As a result, gas "which did not meet sales gas specifications" entered the Alliance system. It said there was no risk to the public or to the environment.
"We have offered our assistance to Alliance Pipeline and are working with our producer customers to divert gas and find alternative solutions for their production until regular operations resume on Alliance," Keyera said.
The Alliance Pipeline is jointly owned by an affiliate of pipeline giant Enbridge and Calgary-based Veresen. It runs 3,848 kilometres and carries 1.6 billion cubic feet of natural gas a day.
AltaCorp Capital analyst Dirk Lever said the outage is a "pain in the neck" for producers, but the consequences shouldn't be too dire. He expects the line to be out of service for days, rather than weeks.
"The indications are it's more of a nuisance. Most guys have got interruption insurance, so that may kick in," he said.
"Nobody's happy that this is happening at a low commodity price environment. These things are expensive no matter how you look at it."
So far, Seven Generations Energy, NuVista Energy, RMP Energy and Crew Energy have suspended production as a result of the Alliance outage.