Why investigating wildfires can be a 'tough row to hoe'

As soon as the first reports came in about the northern Alberta wildfires, investigators were already collecting data as part of their hunt to determine the causes.

They wanted to know, among other things, about the weather and any human activity in the area before the fire broke out. 

Knowing that "really helps us understand the potential causes," said Ian Douglas, the B.C. wildfire service enforcement superintendent. 

"This is all the pre-information that you're gathering before you head out the door."

In northern Alberta, firefighters continue to battle the Chuckegg Creek blaze, which covers approximately 127,000 hectares a few kilometres southwest of High Level, Alta. Almost 5,000 people from High Level and nearby First Nations have been out of their homes for a week since the areas were evacuated on May 20.

To the south, in the Slave Lake forest area, a new wildfire started Sunday about 14 kilometres southeast of Trout Lake, a community of about 350 people some 300 kilometres northeast of Grande Prairie. 

Before setting foot on either scene, wildfire investigators checked if there were any lightning strikes in the area in the past three weeks to a month.

Wind speed, temperature, humidity and other weather data will help investigators understand the fire's behaviour and provide some clues to the possible cause.

"It gives us an idea of what's happened in and around the fire," Douglas said. 

Investigators will also review phone reports from the public. Photographs of the early stages of a fire, especially from aircraft, can also be particularly useful. 

"There may be some really good nuggets of information we want to get into a little more," Douglas said. 

Lots of data

But the sooner investigators are at the scene, the better, he said.

By that time, the fire will "hopefully" be smaller, he said, giving them a better idea of where it started.

"There's a lot of things to do. And a lot of data to collect," Douglas said. 

Investigators will search for "macro scale indicators" — any object that's been affected by the fire going near it or over it, leaving soot or stains that they can interpret.

"The nuts and bolts of the fire investigation is knowing and understanding indicators," Douglas said.

"It's a tough row to hoe. Once you've spent the day on site, you're dirty, you're hot and you're tired and it's 38 degrees."

Investigators will get down on their hands and knees, placing flags in the ground wherever they see an indicator.

"You have to get down, in some cases right on your belly, and have a look at with with a magnifying glass you to see what the vegetation is doing how it's burned and that sort of thing," said John McDermitt, president of the Fire Investigation Association of Alberta.

Burn marks on objects, or the byproducts of burning, will tell investigators which way the fire was burning at that point.

"Once you've got your scene all flagged, you're able to take that step back and actually kind of take it all in and say 'OK, well you know it makes sense that this was the path of the fire. This is where it was going and this is where it came from," McDermitt said.

Not getting fixated

There are nine general fire causes which include campfires, lightning and problems with equipment — which can be broken down into smaller groups of causes, such as railways or hydro lines.

Knowing that "helps us define what we're finding out there, so that we're working ourselves back to the origin," Douglas said.

For example, if they come across a cigarette butt, they will mark it, but not get fixated on it, he said. 

"Not until we find an origin, and then we get really fixated on things. Generally speaking, there's so much crap out in the bush," Douglas said.

"We just want to document what we found. It's just as important for us to identify a cause but also eliminate all the other causes."

Once they have located what they believe to be the general fire ignition area, investigators will get down on their hands and knees again and grid the area.

"We'll thoroughly search that area, see if there's anything there we can find that has started that fire," Douglas said.

They will document each pin flag, photograph, GPS it, and map the area.

By the time investigators leave the site, "99 per cent of the time" they know what started the fire, said Douglas.