Alameda – A plant operational upset at Keyera’s Simonette gas plant, located 60 kilometres southwest ofValleyview, Alta., led to the complete shutdown of the Alliance Pipeline system in early August.
On Aug. 6, Alliance Pipeline advised in a press release, “An amount of hydrogen sulfide (H2S) entered into its mainline pipeline system as a result of complications experienced by an upstream operator.
The next day the pipeline company met with stakeholders, stating in a release, “Alliance is carefully and safely managing the situation. In order to correct the situation Alliance is commencing mitigation activities which are expected to result in a zero flow condition on the pipeline. It is anticipated that this will begin impacting commercial stakeholders mid-morning on August 7, 2015 and will continue for an indeterminate amount of time.
The H2S has been isolated in a section of the Alliance mainline where it will safely remain until it is removed through the flaring process.
As part of this, Alliance plans to flare the impacted natural gas in order to safely dispose of it. This is planned to occur within the confines of Alliance’s Alameda compressor station in Saskatchewan. There is no risk to human health and no environmental impacts are expected, the company said in a release.
“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 Daniel Sutherland, Alliance’s vice-president, commercial operations. “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 Pipeline will provide updates in the coming days regarding the length of the pipeline shutdown.
Keyera’s press release of Aug. 7 noted, “There was no risk to the public or to the environment as a result of this upset. However, gas which did not meet sales gas specifications entered the Alliance Pipeline system.
“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 representative Nick Kuzyktold Pipeline News the duration of the flow of H2S-contaminated gas was "a brief period Wednesday morning," and that it was "single-digit" hours.
That plant is one of 68 receipt points on the mainline pipeline, making up a small fraction of total volumes on the Allliance system.
The Alameda compressor station is located four miles north of Alameda and one mile west of Highway 9, at 4-25-4-3-W2.
The Alliance Pipeline was constructed in 1999 and 2000, and collects near all of its gas from northeastern British Columbia and northwestern Alberta. However, it does have a delivery receipt point in Saskatchewan from the Steelman gas plant, which is just a few miles west of the Alameda compressor station. There is also a lateral that runs from Tioga, North Dakota, to the mainline just south of where it crosses the Canada/United States border south of Gainsborough. The pipeline’s delivery point is the Aux Sable natural gas liquids and extraction facility at Channahon, Illinois, about 50 miles southwest of Chicago. All of the gas delivered via the Alliance Pipeline is processed at ASLP’s Channahon NGL Facility
Aux Sable states it is one of the largest NGL extraction and fractionation facilities in North America.
