Investigations of Wildfire and the Growing Natural Hazard
By Jeff Berino, B.S. CCFI, CFEI
The wildfire problem of the United States continues to plague homeowners, firefighters, and insurers. 2015 was the worst year on record with approximately 62,000 reported wildfires and approximately 10 million acres consumed. The suppression costs alone may reach1.5 Billion. (Source: National Interagency Fire Center) Do we have your attention yet?
As more homes are constructed in the Wildland/Urban Interface zone, the area where forested land and homes/communities meet, these wildfires are becoming more problematic every year. The impact to the industry continues to rise at an exponential pace. Wildfire investigations have become more sophisticated over the last few decades. NFPA 921, considered an authoritative guide in fire investigation, now has a newly expanded and accurate chapter solely dedicated to wildfires.
A wildfire scene examination typically begins with witness and firefighter interviews. An experienced investigator will then circle the fire or, if possible, the general area of origin several times. The investigator should travel first in a clockwise circuit followed by a counterclockwise circuit. Experienced investigators will look for macro patterns, which include larger burn patterns on heavy fuels, telephone poles, staining on rocks, needle freeze, char patterns, and bevel patterns on some heavy fuels. Heavy fuels are defined as fuels of large diameter such as logs and large limb wood that are consumed more slowly than flash fuels.
Investigators also will track the movement of the fire, which will help them perceive where the specific area of origin of the wildfire is. Areas where the fire advanced are determined based on pattern analysis and marked with red flags. The flank, or sides, of the fire are noted and marked with yellow flags. Finally, areas where the fire backed or slowly crept back against the wind or topography are marked with blue flags. Spot fires, or fires which result from flying embers, cause the investigator to re-evaluate the patterns to determine if they are in the correct area.
Once a specific area of origin is determined using macro pattern analysis, the experienced investigator will use micro pattern analysis. Micro patterns may include shadowing on pine cones, curled grass, and slight staining on smaller fuels. The investigator will also mark these micro patterns with flags. A grid is used to begin the search for the specific cause of the fire within the area of origin. String lines placed about 12 inches apart are set up in a parallel pattern, and each area in the grid is carefully searched visually, then with a magnet.
Some of the possible causes of wildfires include lightning, flares, catalytic converter heating, carbon flakes from exhaust, sparks from railroad trains or friction as seen in heavy equipment, cigarettes, holdover fires, escaped campfires, electrical power lines, and welding operations.
Wildfire investigation can be daunting for investigators trained in structural fire origin & cause. Wildfires are usually investigated from the area of most damage to that of the least, opposite of the methodology used in structure fires; thus, a fire investigator with specific training must be retained. An investigator with additional wildfire suppression experience can be invaluable to understanding the fundamentals of wildfire behavior. Investigating wildfires and investigating structural fires are two vastly different fields. It is important to choose a firm and investigators with specific wildfire behavior knowledge and training.
Jeff Berino has over 36 years in the fire service, and over 36 years of fire investigation experience. Jeff is a Certified Colorado Fire Investigator, Nationally Certified Wildfire Investigator, Nationally Certified Fire and Explosion Investigator and a Nationally Certified Type III Incident Commander for Wildfires. The article first published in March of 2016.