Transitioning from Urban to WUI Firefighting

This past summer, when you picked up a newspaper or turned on the television or radio, you were almost guaranteed to read or hear headlines about “raging and uncontrollable wildfires.” From California to Florida, wildfires are becoming more frequent every year. Right? Not exactly.

Wildfires have been a part of the ecological cycle long before we as a civilization decided to expand our neighborhoods into fire-prone areas. It’s only in recent years that we have we become more aware of wildfires due to the catastrophic losses endured by civilians.

Here lies our ever-increasing challenge as structural firefighters: We train on extinguishing structure fires; depending on where you live, you may also train on battling wildfires. But as efficient as we may be at each one of these disciplines separately, putting a structure in the path of a wildfire complicates the problem, creating an incident that’s not simply structural or wildland.

The strategies and tactics applied to a wildland/urban interface (WUI) fire are vastly different from our everyday tactics. The first step: Change your mindset. This isn’t a structure fire, so you can’t treat it as one. There are many more factors to consider, such as access, water supply and usage, time of day, your familiarity with the area and, most importantly, weather and fuels. When was that last time you had to check the relative humidity (RH) or the type of landscaping present at a standard single-family residential structure fire?

As in most cases with the fire service, evolving or adapting to WUI fires starts with training.

If your response zone includes WUI, or if you respond mutual aid for assistance, you should establish a minimum training requirement for all personnel. In 2007, the Florida Fire Chiefs Association adopted a minimum standard of training for all personnel responding to regional wildfire deployments (see below). The standard is clearly written to establish minimum qualifications for firefighters, company officers and strike team leaders. The courses required are provided through the Florida Division of Forestry and include interagency training. WUI fires bring wildland firefighters and structural firefighters together on one incident, so training together is key.

Preplanning WUI areas is just as important as preplanning commercial strip malls or large, multi-family dwellings. First, identify the vulnerable area and the major hazards. Residential homes are not the only structures in danger. Infrastructure such as lift stations, power lines, bridges and local utilities are all subject to damage.

Next, make a map of the area to include access and egress routes, hydrant or draft site locations and total number of structures. A general rule of thumb: If two structures are within 50 feet of each other, one Type 1 structural engine should be able to protect both structures. Structures more than 50 feet apart will need a dedicated engine. If you’re planning for a neighborhood with more than 20 structures, take the number of homes on the perimeter in danger and divide that number by four to get the number of single engines needed. Add one additional engine strike team for back-up, two if there are combustible roofs.

A preplan that displays access routes, water supply and the total number of strike teams to adequately protect the structures in the area will go far to produce a successful outcome.

Another excellent tool: Firewise Communities, a program developed to help communities assess their fire danger. Identifying and mitigating problems such as inadequate defendable space, heat traps, combustible landscaping and fuel loading may save time and valuable resources.

Fuel Characteristics
I have no doubt that any seasoned structural firefighter can recognize fuel-loading hazards found in a standard warehouse or commercial occupancy. Identifying these hazards is ingrained in our way of thinking and affects our tactics as a whole. But can that same firefighter recognize the fuel characteristics surrounding a structure threatened by an approaching fire front?

One excellent way to find out how the fuels will react to fire and weather conditions is to coordinate training with the local forestry agency and have your personnel witness a prescribed burn. In some cases, if your personnel have the proper training, they may be able to participate in the burn. Understanding the fuel arrangements and how they will react to weather and topography will help provide a baseline that a firefighter can use to assist in decision making when triaging and protecting structures.

Weather is probably the most important factor to a wildfire. Understand weather patterns in your area, and when fire is a threat, obtain consistent weather updates. Along with determining the fuel characteristics, understanding the role weather plays will assist in the decision-making process. Key severe fire weather indicators include:

  • Relative humidity (RH)
  • Temperature
  • Wind direction

Tip: For every 20-degree rise in temperature, your RH value will reduce by 50 percent. Example: If the day starts with a temperature of 70 degrees with an RH of 90 percent, and the projected high by mid-afternoon is 90 degrees, then the RH will be around 45 percent by mid-afternoon. Now factor in a 10- to 12-mph wind, which will speed up the drying process, and you could be seeing an RH in the mid 30s.

Temperature also plays a big role in wind speed and direction. Know the regular weather patterns in your area and what causes them. For example, if you’re near the ocean, high temperatures during the day will cause the air over land to increase and rise, drawing in the cooler air from over the water known as a sea breeze. As the sun sets, the air cools and drops, causing the wind to shift and push back over the now comparatively warmer waters. Pay attention to the calming winds in the late afternoon or evening; this is usually an indicator that a change in wind direction is on its way. Knowing the standard weather patterns will provide an insight into fire behavior.

Structural Protection
Structural engines are the primary apparatus used for structural protection during a WUI fire. It makes sense: Put the firefighters with the most structural training in position to protect the residences in the path of a wildfire.

Note: Structural protection is not fire attack. Most WUI structure fires are the result of falling embers. The water in your tank will be most effective when used to extinguish these embers and other spot fires that start near the home. If you decide to make a direct attack on the fire, chances are your water will run out and you’ll leave the structure more vulnerable. If fuels are close enough to ignite a fire from radiant heat, then the structure may not have been defendable to begin with. This is why it’s so important to promote 30 feet of defendable space to all residents that live in your WUI zones.

Structural Triage
Structural triage falls into three categories that correlate to the three levels of triage in a mass-casualty incident (MCI). 1. Needing little or no attention. There’s little or no prep work needed to protect these structures. They will probably survive due to their defendable space and construction. These would be equivalent to a green tag for MCIs. 2. Needing protection, but defendable. With a small amount of prep work and crews staged on site as the fire front passes, these structures will probably survive. This would be equivalent of a yellow or red tag. 3. Not defendable. Will require too many resources and too much time to defend. Like a black tag on an MCI patient, you wish that there was more you could do but your efforts would be futile. Your job conducting triage is to save the maximum number of homes.

If you and your crew have decided to stay and defend the structure, remember these pointers:

  • As always, position your apparatus facing the path of egress. If you’re a strike team leader, scout the area, and have a plan of where you want to place your apparatus. It’s far easier for you to maneuver in these areas with a staff car than it is for large, clumsy engines.
  • Remove debris and potential fuels from around the home, especially from around the windows and under the heat traps. If debris under a window ignites, it will easily penetrate the structure.
  • Even though it feels like a preventative measure, pre-wetting a structure and the fuels around the structure has limited success. The intense heat from the fire will quickly heat the fuels to the point of ignition. If pre-wetting is your tactic of choice, be sure to use foam or gels. Foam helps to reduce the water usage and has some “staying power.” Gels are helpful but can be difficult for the homeowner to remove.
  • Stretch 1 ½” hoselines no more than 200 feet. Be sure to have one on either side of the structure. This will provide coverage to all sides and will provide a back-up line if one ruptures. Set the nozzle to the lowest gpm possible to conserve water.

A Final Word
Remember: Keep your focus. Just because you may be assigned to structural protection a mile ahead of the fireline and you’re not putting any water on the fire doesn’t mean that you and your crew aren’t contributing. Everyone has a role at a WUI incident. If you’re assigned to structure protection, you’re the last line of defense, and the fact that you’re needed may be an indication that something went wrong earlier in the incident to allow the fire to advance.

Some structural agencies have been mitigating WUI fires for years and have become very efficient. Every year more neighborhoods are being developed in WUI zones, causing more structural agencies to adapt to the strategies and tactics needed to properly protect homes in the WUI. Through awareness, training and education, we can solve many WUI problems before they become catastrophic.

Sidebar: An LCES Refresher
Understanding lookouts, communications, escape routes & safety zones

No matter how many times you’ve reviewed it, LCES is a powerful tool to help you remember WUI safety basics.

Lookouts. Always have someone from your crew, preferably a crewmember with a background in wildfire, posted as a lookout. Keep good, open communications with them as they constantly look for changing fire conditions. Even though all members are essentially “lookouts,” designating one person to this assignment is imperative.

Communications. Post-incident critiques often identify communications as a problem area. Specific issues can include too many units on one channel, unnecessary radio traffic or no common communications at all. Communications should be broken down into command channels and tactical channels. Depending on the size of the incident, you may need to assign each division to a separate channel. Too many units on the same channel can be like having no channel available at all. Although you don’t necessarily need to know what everyone in the incident is doing, pay attention to the radio traffic. Situational awareness is important for all crewmembers.

Escape routes and safety zones. Constantly monitor escape routes and safety zones. As you move locations, re-establish and identify the nearest safe areas. Be sure that all of your crewmembers are aware of the locations of escape routes and safety zones. Make a habit of questioning them to be sure that they are always on the same page.

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