Wildland fires in California have quickly made its way to being a household conversation year-round. 20 years ago, wildland fires in California were not being discussed as much because there was a traditional fire season that these fires burned in, the fires typically didn’t threaten as many homes and occupied areas, the forest ecosystem was healthier, and the weather was significantly different.
It is estimated that 1/3 of the homes in the US are built in wildland fire prone areas. In California alone approximately 25 million people reside in high severity zone wildland fire areas. These facts are examples of the challenges firefighters face worldwide when dealing with fires is the Wildland Urban Interface (WUI). This article will discuss command and control considerations of WUI incidents.
The 3 main factors contributing to wildland fires potential are fuels weather and topography. Combined these factors will play a significant role in the fires growth and intensity.
Fuels are going to play a major role in the fires rate of spread, overall growth, and intensity. Convective and radiant heat intensity will be dictated by what fuels are involved and what form they are. Fuel type will also determine if spotting or downwind ember cast will be a factor. Fuels can be divided into 3 categories;
- Natural growing fuels such as grass brush and trees will likely be the driving force in the rate of spread and the initial heat potential affecting the fire.
- Ornamental plants generally planted for landscaping purposes such as oleanders, junipers, eucalyptus and palm trees are very susceptible to fire and can cause significant challenges to firefighters due to radiant and ember cast. Especially when they are planted in proximity to structures and other infrastructure i.e.: power lines and propane tanks.
- Man-made fuels such as structures, fencing and yard debris i.e. junk tires and wood piles these fuels once they have ignited will often generate a tremendous amount of radiant heat and likely create additional exposure challenges for firefighters.
Weather often plays the biggest role in a wildland fires potential. Temperature, relative humidity, wind and atmosphere pressure all have an impact on a fires growth potential. High daytime temperatures and low relative humidity will decrease the moisture in naturally growing fuels making them more vulnerable to ignition. Wind will also assist in drying fuels but its impact on spread and spotting potential is of the greatest concern. Pressure systems also play a role. Basically during a high pressure or stable weather pattern fires will generally be influenced by fuels and topography versus a low pressure or unstable weather pattern fuels topography and upward air currents will drive the fires intensity. Unstable weather patterns may also present gusty winds dust devils downdrafts thunder storms all of these may create extreme fire behavior or fire storm conditions making conventional or direct attack unsafe for firefighters.
Topography or the lay of the land will affect the fires spread and intensity as well. Steep slopes drainages chimneys and saddles are all areas firefighters must avoid or be at a heighten sense of awareness during wildland firefighting operations. Fire naturally wants to run upslope and will move with intensity particularly in these terrain features.
When you add structures often times built on ridges or midslope only accessed by narrow roads and driveways firefighters are at a tremendous disadvantage. Rule of thumb if you are trying to defend structures that are above a fire in alignment the wind you are in a very dangerous position.
Running, head, or active flank fire is the most active portion of the fire.
Backing fire is the least active flank, the flank burning downslope or against the wind. Spotting is caused by firebrands or ember cast carried aloft into the convective column and wind. If these brands or embers land in a receptive fuel a spot fire will occurs.
Fire Suppression Strategies and Tactics
Suppressing fire directly on the fires perimeter. This is done utilizing a progressive hose lays or mobile attack. This can also be accomplished by
using back pumps and hand tools
Hand Tools though are not recommended when flames exceed 4 foot in height.
Indirect attack is defined as backing off the fires perimeter and constructing a fireline utilizing hand tools dozers tractor plows. This strategy allows FFs to take advantage of natural and man-made barriers to encircle the fire. Back firing is often necessary to complete this operation.
Both direct and indirect strategies have theirs pros and cons. Often times if structures are threaten and at risk a direct attack is required to defend them.
Intermix is defined as structures that are mixed in amongst natural growing vegetation.
Interface is defined as structures generally in the form of neighborhoods that border naturally growing vegetation.
An acronym that has been developed to assist firefighters in determining which structures are defendable and which ones are unsafe to defend is SFACTS;
- Initial Assessment: can you survive here? If not, LEAVE NOW!
- Is there a Safety Zone nearby? If not, LEAVE NOW! (IRPG)
- Do you have a viable Escape Route?
- What is the decision point at which you will leave based on fire behavior and rate of spread?
- Is there a Temporary Refuge Area (TRA) on site? If not, LEAVE NOW! – Preplanned area for immediate, temporary refuge — Use of fire shelter should not be necessary – Is there a viable Escape Route to the TRA or Safety Zone?
- Is “Prep and Go” tactic an option?
- Do you have communications with your supervisor and adjoining forces?
- If safety issues cannot be mitigated, LEAVE NOW!
- Can you survive based on current and expected fire behavior? If not, LEAVE NOW!
- Look up, Look Down, Look Around Indicators: – Fuels (characteristics, moisture, temperature) — What will the intensity of the fire be when it arrives? — How long will it take to consume the fuels? – Wind — Current speed/direction — Expect changing winds – Terrain — Are you in a chute, chimney, or saddle? If yes, LEAVE NOW! — Is wind in alignment with topography? — What is your position relative to topography? — Are you mid slope or on top of a ridge? – Atmospheric Stability – Fire Behavior (requires constant monitoring) — Spotting, crowning, sheeting, rate of spread? — Flame length and height?
- Other weather considerations: – What is the current relative humidity? — Is there an expected change? – Are thunderstorms forecasted?
- Is access compatible with time and distance factors necessary to utilize as an Escape Route to a Safety Zone? – Road surface adequate for speed necessary? – Adequate width? – Turnaround/turnouts? – Bridges within limits for fire apparatus? – Drainage ditches/culverts? – Steep grades? – Is there a safe place to spot apparatus? STRUCTURE DEFENSE GUIDE Structure Triage Decision Process (S-FACTS)
- Does the structure have adequate defensible space, based on topography, fuels, and current and expected fire behavior?
- Can defensible space problems be mitigated quickly?
- Will building materials and yard clutter compromise safety?
- Is the construction wood siding or shake shingle roof?
- Are there vent openings, open eaves, large glass windows facing fire front, decks with vegetation below? – Will ember intrusion through attic or foundation vents be a problem?
- What are the contents in the garage and outbuildings?
- Are there hazardous materials present?
- Are there propane tanks, fuel tanks, or power lines?
- Is there an adequate water supply nearby?
- Are additional resources needed to mitigate issues?
- Consider “Prep and Go” or “Prep and Defend” tactics
- Is there time for an adequate size up of the structure defense problem?
- Is there time to mitigate safety concerns?
- Is there time and adequate resources to properly prepare and defend the structure?
- Is there time to escape, utilizing Escape Routes, to a Safety Zone? If not, LEAVE NOW! STAY OR GO
- Tactical decision based on the S-FACTS
- Is it safe to stay? If no, utilize “Check and Go” tactic
- Is there time to prepare the structure for defense and what will the fire behavior be when the fire gets here?
- “Prep and Go” or “Fire Front Following” tactics should be used when it is not safe to “Prep and Defend”
- Are you adhering to the 10 Standard Firefighting Orders? (IRPG)
- Have you considered the 18 Situations that Shout Watch Out?
- Have you considered the Common Denominators of Fire Behavior on Tragedy Fires? (IRPG)
- Are you maintaining LCES? (IRPG)
- Look Up, Look Down, Look Around (IRPG)
- Have Decision Points (“Trigger Points”) been established?
- Conduct Risk Management (IRPG) – Situational Awareness – Hazard Assessment – Hazard Control – Decision Point – Evaluate STRUCTURE TRIAGE CATEGORIES Not-Threatened
- Safety Zone nearby and TRA present at structure
- Construction features/defensible space make the structure unlikely to ignite
- Residents may/may not have evacuated Threatened Defensible
- Safety Zone nearby and TRA present at structure
- Construction features/defensible space require structure defense tactics during fire front impact
- Residents may/may not have evacuated Threatened non-Defensible
- Lack of adequate Safety Zone nearby
- Structure cannot be safely defended
- Residents must be evacuated
The following photos and diagrams are from Fire Scope
- Check And Go Threaten Non Defendable or Non Threaten
- Prep and Go Threatened But Requires Some Action
- Prep And Defend Threaten Requires Action But Is Safe To Stay
- Fire Front Following Addressing Impacted Structures Behind The Fire Front
- Remaining Mobil Following The Fire Front
- Bump And Run Addressing Threaten Structures On The Fires Perimeter Staying Mobil
- Anchor And Hold Keeping The Fire From Advancing Further Through A Block Of Structures.
In rural areas water tenders or use of natural water lakes rivers etc. will likely be required to meet your firefighting needs. Suburban areas or areas that are supported by hydrants can allow fire apparatus easier access to water. However supply lines can impede additional apparatus from accessing the area as well as civilians that are trying evacuate. Also if the fire impacts the area power supply pressurized water systems may be compromised. Be careful not to place too much of your plan on your water system have a plan in the event your hydrants fail.
Safety Zones And TRAs
Temporary Refuge Areas or TRAs are areas FFs can take refuge to seek relief from heat and smoke. Examples of TRAs are corners of structures AB corner when fire is impacting C side inside of fire apparatus.
Safety Zones are a predetermined location or area FFs can access via their predetermined Escape Route. A Safety Zone must be large enough for FFs to stay without having to deploy their fire shelters during periods of extreme fire behavior. Examples of safety zones are large open area devoid of fuels allowing for relief from radiant heat.
Both TRAs and Safety Zones must be identified and easily accessible before FFs can engage in suppression activities.
Firefighting is inherently dangerous. WUI incidents increase the hazards FFs will face
significantly. In addition to smoke and heat from a potentially rapidly growing flame front FFs will likely deal with venting propane tanks falling overhead powerlines unsafe driving conditions panicked civilians trying to evacuate hazardous materials that ignite or are threaten by radiant heat. These are just some examples. FFs will also have to deal with heat stress fatigue and exposure to high levels of CO for extended periods of time. Training and good incident communication can minimize these however FFs must maintain appropriate situational awareness and apply good risk versus gain strategy and tactics. Firefighters must review the 10 Firefighting Orders and The 18 Watch out Situations and apply them on all wildland incidents.
Initial Attack Or First Due
First arriving unit officers will need to conduct an incident size up. This will include what you presently have, what will likely happen and your control objectives. Your report on conditions will include your findings your resource needs as well as you assuming command of the incident. An example might be E-1 on scene 2-3 acres of grass burning upslope with a 5 mph NW wind we have an immediate structure threat of 4 structures as well as another 10 plus structures within 30 minutes the fire has a potential of 50 acres assuming 1st St IC.
Resource type and orders
Determining what your additional resource needs is very important to achieving your control objectives. When ordering engines consider how quickly you need them what are you access issues what do you plan to do with them. For example if you need additional engines for structure defense and access is not an issue order Type 1 or 2 closest resource. If you plan to do an extended progressive hose lays and access is a factor Type 3 with 4 wheel drive may be necessary. When ordering crews and dozers again consider type and availability. Ordering resources in Strike Team or Task Force configurations can also be helpful being they come with a leader. During an IA incident ST and TF leaders can serve as Division Groups and other essential IA overhead. The early establishment of a staging area will allow the IC to order your resources prior to knowing exactly where you plan to engage them.
You have done your size up and given your report on conditions. You’ve accessed the heel of the fire and are aggressively doing structure defense combined with perimeter control. Additional units are arriving and asking for assignments. This is a critical point in the overall success of your incident. A thorough working knowledge of the ICS is very important. Consider assigning your next due the opposite flank let’s say in this scenario you’re on the right flank have them take action on the left flank and assign them Div. A. Inform them of your actions and have them update you with their Div. resource needs asap. As your 3 4 5 etc. due arrives they can be assigned as your Div. needs dictate. Your ability to primarily command and reasonable span of control will make your incident much easier to oversee. I personally think it is very difficult to effectively command a growing wildland fire while you are fighting fire. Especially if aircraft are involved. The IC needs to position themselves likely in the cab of their apparatus out of the smoke and incident distractions as much as possible. The overall success of the incident will hinge on the organization and command presence of the IA IC.
In additional to potentially multiple responding fire agencies WUI incidents often require assistance from other agencies as well. Law enforcement can assist with traffic control road closures and evacuations. Utility companies can assist with denergizing powerlines and other utility related hazards. EMS for injuries and animal control just to name a few. Consider identifying a command post early in the incident to keep all responding agencies in the same location minimizing request and communication related issues.
The command and control of a WUI Incident has its challenges. Your ability to address the incidents life hazards, structures at risk, and multiple agencies and resources take planning and practice. These incidents require a good working knowledge of ICS your ability to expand and or contract your plan to meet your incidents control objectives will dictate your success. Annual training in wildland firefighting skills along will pre fire season meeting with your unified command partners will help. Good luck be safe.
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