Tuesday, November 4, 2008

ground fog around their legs

There was an incident that occurred in 1985 that helped improve safety in the pipeline industry. It is referred to as the Camrose Accident. It occurred on a pipeline owned by IPL, now called Enbridge -- the operator of the longest pipeline system in the world.

At 12:42pm, Feb. 19, 1985, the senior shift dispatcher at the Edmonton Control Centre suspected a leak in the No.1 liquid natural gas pipeline based on strange pressure readings. At 1pm, a landowner phoned the dispatcher to report a vapour cloud in a field 27km northeast of Camrose. The No.1 pipeline was shutdown and the road near the leak was barricaded.

At 3:30pm, the Maintenance Foreman and District Engineer arrived and approached the suspected leak site from upwind, using their gas detectors. They found the leak in a slough; the ground was pushed up and white clouds of natural gas were spewing out of the ground, gathering in pockets in low-laying areas (natural gas is heavier than air). At 4:30pm, they radioed the Control Centre and recommended flaring the escaping gas (i.e., lighting it on fire) as darkness was approaching. The District Manager declined. A maintenance crew was sent in to install a "stopple" about 220m upstream (and upwind) of the leak which would plug off the pipeline and allow repairs to take place.

The six man maintenance crew began building an access road with a Caterpillar front-end loader, building a snow buffer (between them and the leak), installing floodlights, and operating the Gradall (an excavation machine similar to a back-hoe). Little did they know that the wind direction had been shifting since they arrived on site.

At about 8:30pm, the men were discussing the smell of gas in the air around them, and what appeared to be a ground fog around their legs. Also they noted the vehicles were stalling or idling roughly and the generator powering the floodlights again had stalled. At this point in time, one of them got into the 2 1/2-ton truck to restart it. Almost immediately, a ball of flame erupted in the cab of the truck and quickly engulfed the whole site. All six men at the site were caught in the fire ball.

Two men received 3rd degree burns to 90% of their bodies and died in hospital. Three men received 3rd degree burns to 30% - 70% of their bodies and lived. One man, Mr. Bone, was uninjured.

The current form of the Pipeline Standard is due in part to the investigation of the Camrose Accident.