We’ve been glued to our radios and TV’s for the last few months with coverage of Ventura and LA County’s wildfires. One of the key indicators of how a firefight is going is frequently given out in news reports. It’s the fire’s containment figure. But, what exactly does that mean?'
It's one of a couple of key terms used by firefighters which are often confusing, or misunderstood by the public.
"What;s import to us is to make sure that the public understands our terminology," said Andrew Dowd, who is a Ventura County Fire Department Public Information Officer. "There's a lot of anxiety. People want answers to what specifically is happening with the fire. So, the more fluent we can make the public in understanding our terminology, the better understanding they will have with these incidents."
Here’s one example of the terminology. Monday night, a wildfire broke out in the Santa Clara Riverbed, near the Ventura/Oxnard border. By midnight, the forward progress of the 60 acre plus had been stopped. The fire didn't damage any structures.
But, that didn’t mean it was controlled, or out.
"Control of a fire has to do with our prediction that a fire is going to move out of an existing footprint," said Dowd. "In a wildfire situation, we use the term forward progress, and what that means is, if you can imagine the acreage of a fire, that is its footprint. When we say forward progress is stopped, that fire is not going to go forward any further. That is a terminology when we have taken a significant amount of heat out of the front of the fire, and we don't expect it to spread significantly beyond its existing footprint."
So, what does it mean when firefighters give out a containment percentage?
"Containment is we have gone around the perimeter of that fire, and we have put in some kind of control feature. It could be a dozer (bulldozer) line, or a hand line, scraped down to mineral soil, all the fuels separated. And, we have mopped up and cooled any heat within the portion of the fire line, and we have verified that it has no resisdual heat by flying it some kind of aviation asset or walking it with hand crews," said Dowd.
Dowd gives us an example of the nuts and bolts of containment works. "Let's just say you had a ten mile perimenter around a large fire. For us to declare 10% containment, it means (there's a line one the edge of) over one mile of that fire...we have scraped down to mineral soil, we have gone in and cooled out the fire, there's absolutely no heat, and we have put water on all the hot spots, and we've flown it with an aircraft, or gone through it with hand crews.," said Dowd. "That process takes time. That's why those containment number can climb slowly."
It can take days, or weeks, especially when there is rugged terrain, because it can be hard to get crews in to do the work.
Dowd said another frequent question about wildfires is the cause. People want instant answers, but he said it isn’t that simple.
"They have to go in and determine a couple of things. The first is the origin. Understand, that origin has been burned up, so using different clues, they can determine where that origin is. Then, they have to determine the cause of the fire. Was it accidental, was it a natural cause..was it intentional? They have to be able to collect that evidence."
Dowd notes investigations routinely include someone who is an arson investigator. He says it doesn’t necessarily mean arson is suspected. He says they look at everything.
It can be frustrating for the public. It takes time, sometimes a year or more, to accurately conclude the cause of something like a major wildfire. But, Dowd said they want to get it right.
Because we live in wildfire country, Dowd said firefighters want the public to have the information they need to understand the status of a fire. He says that type of knowledge can often ease some of the stress associated with the situation.
