The Edmonton Area Pipeline & Utility Operators’ Committee, or EAUPOC for short, is proof that an emergency can bring people together and spark positive change.
he not-for-profit group, comprised of nearly 40 member organizations of industry, contractors, municipalities and regulators was formed almost four decades ago in the wake of an unprecedented pipeline emergency in Mill Woods, Edmonton. Since then, EAPUOC members work collaboratively to educate the industry, commercial and residential diggers on safe digging practices around the extensive infrastructure systems that underpin the Capital Region.
“The urban subsurface plays a key role in accommodating services and other essential resources to meet our community’s growth,” says Melissa Pierce, EAPUOC Board Member. “Be it water, telephone, internet, utilities, petroleum or industrial products, there are complex and integrated networks underfoot that require our utmost attention.”
Tucked away so as not to disrupt communities or neighbourhood aesthetics, these networks are easily forgotten. However, on Friday March 2, 1979, industry professionals, city officials and residents in Mill Woods got an unanticipated reminder when a pipeline ruptured and triggered one of the largest peacetime civic evacuations ever.
“This incident not only created a serious ripple of events in the southeast suburb, it forever changed our collective awareness and the way we communicate, plan, operate and design these essential connections, ” explains Pierce.
The Pipeline and Incident
The infrastructure at the centre of the emergency had been in operation since 1961. For 18 years, the 22cm diameter pipeline shuttled liquid propane, butane and condensate from a pump station in Rimbey to a liquid petroleum gas terminal in Edmonton without any major issues.
Looking back, it is now clear that the emergency in Mill Woods was a result of the perfect storm of issues. With control valves partially closed and pressure mounting in the passage beneath 12th avenue, the pipeline contents chose the path of least resistance.
At 11:55am, a steady flow of liquid propane burst through a previously damaged area of the pipe, creating a narrow 45cm split. Once at the surface, the liquid began pooling, causing the situation to escalate even more as a flammable propane cloud developed.
Windy conditions did not help. The low cloud of propane gas drifted through the community and eventually caught fire, causing serious injuries to a driver and destroying the vehicle that ignited the escaped gas. The fire also flashed back to the fuel source and fed by propane from the rupture, burned for 16 hours.
As the propane vapour continued to traverse the community, it also made its way into nearby storm sewer systems. This coupled with existing explosive mixtures, prompted first responders to evacuate more than 19,000 residents from their homes. People were not given the all clear to return home until extensive flushing of the sewer lines with water and nitrogen gas had been completed. This took nearly a full day.
Following an inquiry by the Energy Resource Conservation Board (now the Alberta Energy Regulator), it was determined that third-party damage was the root cause of the rupture. At least, three deep gouges were found on the pipe wall. The report findings state “the evidence strongly indicates that the (damages) occurred as a result of construction activities” in the area. A lack of adequate supervision and inspection combined with unsatisfactory methods of locating and exposing buried pipelines lead to a dangerous situation affecting thousands of Edmontonians.
“While this was a terribly unfortunate ordeal that could have been avoided if both the construction contractor and the pipeline company had better processes in place for work near the pipeline, EAUPOC recognizes its significance,” says Pierce. “The silver lining to that dangerous propane cloud so long ago is that it inspired collaboration and local improvements that have continued to protect Edmontonians to this day. We are indeed proud of the distance travelled with regard to improved industry awareness, enhanced emergency preparedness and increased capacity to respond effectively to a linear infrastructure emergency.”