EUB probes Scotford upgrader gas release, Waterton gas field pipeline leak
A November 19 gas release and fire at Shell Canada's Scotford upgrader forced the evacuation of a number of workers from a section of the facility. Following a operational upset, the gas, containing mostly hydrogen, some light hydrocarbons and 6.5% hydrogen sulfide (H2S), leaked from one of the upgrader's two residue hydroconversion units, which upgrade bitumen into synthetic crude oil.
Vapours from the leaking gas ignited and the subsequent fire was quickly suppressed by emergency response personnel from Shell and Strathcona County. There were no injuries to Shell employees or members of the public.
The release was isolated and although there were public reports of off-site odours, air quality monitoring detected no off-site H2S levels exceeding ambient air quality guidelines; no public evacuations were necessary.
The incident is being investigated by the Alberta Energy and Utilities Board (EUB), as is standard practice in these situations. The EUB is also continuing to monitor air quality in the region.
The Scotford upgrader, near Fort Saskatchewan, was the site of two sour gas incidents in September 2006, neither of which caused injuries to Shell employees or members of the public. Following its investigation of these occurrences, the EUB directed Shell to: schedule an exercise to test a new automated call-out system and report its completion to the Board; conduct an emergency response plan exercise; and report completed updated resident information for 2007 to the EUB to ensure that all members of the public are fully informed about how to shelter during an incident.
The Board said its investigation of this latest incident will use additional resources to focus on technical aspects of the facilities involved, with the goal of preventing a recurrence of similar incidents.
The EUB is also investigating a leak that occurred the same day in a sour gas pipeline operated by Shell Canada in its Waterton gas field, about 20 kilometres west of Pincher Creek. As a result of the leak, several residents were briefly evacuated and others living within about a five-km radius of the incident were advised to remain in their homes as a precautionary measure.
Following the early morning leak, Board and emergency services personnel worked together to isolate the leak and depressurize the line in order to repair it. All appropriate authorities were notified and air quality monitoring conducted by EUB staff.
"Our monitoring system allowed us to act quickly and notify residents in the area. Our emergency response system worked as designed," noted Bill Kinoshita, operations manager at the Waterton complex.
Pipeline failures in Alberta are rare, the failure rate in 2005 reaching a record low of 2.2 failures per 1,000 km of pipeline. This represents a 30% drop from 2000, when there were 3.3 failures per 1,000 km of pipeline. The EUB is responsible for regulating 392,000 km of pipeline in Alberta, including over 18,000 km of operating sour gas pipelines.