Is a little pre-fire mitigation around structures better than none?

According to experience from Colorado’s Fourmile Canyon Fire, sometimes the answer is “No”.

When Dave Lasky was leading the effort in the Four Mile Fire Protection District not far from Boulder, Colorado conducting pre-fire mitigation near structures, he and others assumed that doing SOMETHING, cutting trees and building slash piles, would be better than doing nothing. They realized it would not be the total solution in the wildland-urban interface (WUI), but when the Fourmile Canyon Fire started on September 2, 2010 the Fire Protection District found out how wrong they were.

Fourmile fire_map_MODIS_0418_9-8-2010
Map of the Fourmile fire near Boulder, showing heat detected by the MODIS satellite at 4:18 a.m. Sept. 8, 2010. Map by Wildfire Today and NASA.

After the ashes cooled, Dr. Jack Cohen, a U.S. Forest Service fire researcher who has investigated the effects on structures at numerous WUI fires, found what he has seen many times before (more details here). Most of the damaged homes, 83 percent in this case, ignited from airborne fire embers or surface fire spreading to contact the structure; not from high intensity crown fire or direct flame impingement.

The fuel reduction along travel corridors may have helped residents to evacuate, but the unburned slash piles, Mr. Lasky said, could have been a problem:

 In several areas, our crew’s piles were associated with complete stand mortality. We created ladders into the canopy. At best, these unburned piles represented a sad waste of money, and at worst, it is possible that if we hadn’t treated them, these stands might not have carried fire.

Below are excerpts from an article written by Mr. Lasky about what he learned. It first appeared at the website for Fire Adapted Communities Learning Network.

“Doing something is not better than doing nothing.
When the mitigation crew approached residents in the past, they often said, “I didn’t move up here to see my neighbors. I don’t want to cut trees.” In an effort to build momentum, we often performed work that we knew was not reflective of the best science, cutting fewer trees than we should have. This practice was in regard to both defensible space as well as shaded fuel-break projects. The hope was that as communities adjusted to the cosmetic changes, we’d be able to reenter and accomplish more.

“I still hear many colleagues say “let’s just get something done.” I believe this is wrong. We need to do it right or not do it at all. Half measures are proven to fail and engaging in them has great reputational costs. In the current climate of high-profile, catastrophic fires, I am not interested in fear mongering. But I am interested in applying our limited resources to only those communities that are fully committed.

“It’s not just about cutting trees in the wildland-urban interface.
Fuels crews are run by firefighters. Perhaps they should be run by architects. In retrospect, we spent far too much money on fuels reduction and not enough on assisting residents with the installation of fire-resistant building materials and landscaping. Few of the homes lost were directly impacted by crown fire; rather, embers undoubtedly ignited the fine fuels around them, which eventually led to the loss of entire structures. In many instances, residents would have been better served by our crew putting a decorative stone perimeter around the structure. Many residents are capable of cleaning gutters, but less can move tons of gravel. We had chainsaws, and we knew how to use them. We should have picked up our shovels instead.”

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Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire.

4 thoughts on “Is a little pre-fire mitigation around structures better than none?”

  1. Been living in places that are almost totally cinderblock structures, from commercial to residence (because of termite problems) so the modern typical American homes really look flimsy. It really hasn’t been responsible – the houses go up like mushrooms – they aren’t sturdy. This past year – too many examples of how fast they catch fire and burn. 🙁
    So, very much agree with the comment about ‘architects’. There’s no one magic bullet fix for all. Each place has its particular factors – but a combination of clearing/building construction/materials/walls/wind breaks/landscaping suggestions can be done. Architects and landscape designers are able to create all sorts of clever and attractive ground plans for all budgets that reduce fire vulnerabilities while pleasing the residents. Work with the people who are interested, help those who have a tight budget, respect that people like privacy and an attractive surrounding.
    It’d be clever to have a renovation home tv show – rebuilding or renovating with wildfire improvements. A fun way to educate the public while providing useful improvements?

  2. Well this article is misleading because they never completed the fuels project. They never burned the piles prior to a fire passing through, so they didn’t reduce the fuel load, they just rearranged it’s continuity. So to say fuels work isn’t effective is just gonna give homeowners more reason not to reduce fuels around they’re home. Especially if they only read the first few paragraphs and move on.

    1. I understand what you’re saying, Mr. or Ms. Gumby. However, the headline refers to “a LITTLE pre-fire mitigation”, and the sub-headline says “SOMETIMES the answer is ‘No'”. (emphasis added)


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