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Wildland and Ground Fires
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Objectives (1 of 3) Define the terms wildland and ground fires.
20 Objectives (1 of 3) Define the terms wildland and ground fires. Define light fuels, heavy fuels, subsurface fuels, surface fuels, and aerial fuels. Describe how weather factors and topography influence the growth of wildland fires.
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Objectives (2 of 3) Define the parts of a wildland and ground fire.
20 Objectives (2 of 3) Define the parts of a wildland and ground fire. Describe how wildland and ground fires can be suppressed. List the hazards associated with wildland and ground firefighting.
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20 Objectives (3 of 3) Describe the personal protective equipment needed for wildland firefighting. Explain the problems created by the wildland urban interface.
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What are Wildland Fires? (1 of 3)
20 What are Wildland Fires? (1 of 3) Defined by NFPA: Unplanned and uncontrolled fires burning in vegetative fuel that sometimes includes structures. Can consume grasslands, brush, and trees of all sizes Incidence varies from season to season. Referred to by different terminology
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What are Wildland Fires? (2 of 3)
20 What are Wildland Fires? (2 of 3) Ground cover fires burn loose debris on the surface of the ground. Some fire departments respond to more wildland and ground fires than to structural fires. Many structural fire fighters are called on to extinguish wildland and ground fires at some point. Must have proper training
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What are Wildland Fires? (3 of 3)
20 What are Wildland Fires? (3 of 3) Large wildland fires are handled by specialized agencies. Each state has an agency designated to coordinate wildland firefighting. There are federal agencies that are responsible for coordinating firefighting activities at large incidents.
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Wildland and Ground Fires and the Fire Triangle
20 Wildland and Ground Fires and the Fire Triangle Wildland and ground fires require the same three elements as structural fires. Fuel, oxygen, and heat In wildland and ground fires the conditions under which fuel, oxygen, and heat come together to produce a fire are different. Weather conditions have a great impact on wildland fire behavior.
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The Wildland Fire Triangle
20 The Wildland Fire Triangle
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Fuel (1 of 2) Primary fuel is area vegetation.
20 Fuel (1 of 2) Primary fuel is area vegetation. Amount of fuel in an area ranges from sparse grass to heavy underbrush and large trees. Some fuels ignite readily and burn rapidly when dry. Others are harder to ignite and burn more slowly.
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Fuel (2 of 2) Vegetative fuels can be located:
20 Fuel (2 of 2) Vegetative fuels can be located: Under the ground (roots) On the surface (grass and fallen leaves) Above the ground (tree branches)
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20 Fine Fuels Includes dried vegetation such as twigs, leaves, needles, grass, moss, and light brush Ground duff Partly decomposed organic material on a forest floor Main type of fuel in ground cover fires Aid the ignition of heavier fuels
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20 Heavy Fuels Includes large brush, heavy timber, stumps, branches, and dead timber on the ground Slash Consists of the leftovers of a logging operation Do not spread a fire as rapidly as fine fuels Can burn with a high intensity
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Subsurface Fuels Located under the ground
20 Subsurface Fuels Located under the ground Roots, moss, duff, and decomposed stumps Fires involving subsurface fuels are hard to locate and extinguish.
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Surface Fuels Located close to the surface of the ground
20 Surface Fuels Located close to the surface of the ground Include grass, leaves, twigs, needles, small trees, and slash Brush less than 6' above the ground Sometimes called ground fuels Involved in ground cover fires
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Aerial Fuels Also called canopy fuels
20 Aerial Fuels Also called canopy fuels Located more than 6’ above the ground Usually trees Includes tree limbs, leaves and needles on limbs, and moss attached to the tree limbs
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Other Fuel Characteristics
20 Other Fuel Characteristics May determine how quickly the fuel ignites, how rapidly it burns, and how readily it spreads to other areas
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20 Size and Shape of Fuel Size and shape of a fuel influences how it burns. Fine fuels burn more quickly than heavy fuels. Requires less heat to reach their ignition temperature
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Fuel Compactness Influences the rate at which a fuel will burn
20 Fuel Compactness Influences the rate at which a fuel will burn Air cannot circulate in and around fuels that are tightly compacted. Subsurface fuels burn more slowly than aerial fuels.
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Fuel Continuity Refers to the relative closeness of wildland fuels
20 Fuel Continuity Refers to the relative closeness of wildland fuels Are close together or touch each other Allows fire to spread from one area of fuel to the next Have a sufficient supply of air to support rapid combustion Burn much more rapidly than fuels that are compact
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20 Fuel Volume Refers to the quantity of fuel available in a specific area Amount of fuel in a given area influences the growth and intensity of the fire.
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Fuel Moisture Refers to the amount of moisture contained in a fuel
20 Fuel Moisture Refers to the amount of moisture contained in a fuel Amount of moisture in a fuel influences the speed of ignition, the rate of spread, and the intensity of the fire. Fuels with high moisture content will not ignite and burn as readily. Fuel moisture varies with the amount of rain that has fallen.
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Oxygen Oxygen is needed.
20 Oxygen Oxygen is needed. Not usually an important variable in the ignition or spread of the fire. Air movement influences the speed with which a fire moves. Wind speeds the process of combustion and influences the direction the fire travels.
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20 Heat Sufficient heat must be applied to fuel in the presence of adequate oxygen to produce a fire. Three categories of factors may ignite wildland and ground fires: Natural causes Accidental causes Intentional causes
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20 Weather Weather conditions have a large impact on the course of a wildland fire. Moisture Wind
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Moisture (1 of 2) Relative humidity
20 Moisture (1 of 2) Relative humidity Ratio of the amount of water vapor present in the air compared to the maximum amount the air can hold at a given temperature A major factor in the behavior of wildland and ground fires Varies with the time of day and year
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Moisture (2 of 2) Precipitation
20 Moisture (2 of 2) Precipitation Moisture falling from the sky helps to increase the relative humidity. Absorbed by plants Makes them less susceptible to combustion When there is adequate precipitation, fire risk is lower.
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Wind Has the ability to move a fire at great speed
20 Wind Has the ability to move a fire at great speed Effect of wind on a wildland and ground fire is similar to fanning a fire to help it burn more rapidly
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20 Topography (1 of 2) Refers to the changes of elevation in the land, the position of natural, and manmade features Has a great impact on the fire behavior When fires burn on flat land, much of the fire heat will rise into the air. When the elevation rises in the direction the fire is traveling, the fire heat ignites a greater quantity of fuel and increases the speed of fire spread.
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20 Topography (2 of 2) Natural barriers, such as streams and lakes, may help contain fires. Manmade barriers such as highways also make it easier to contain a fire.
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Anatomy of a Wildland Fire (1 of 4)
20 Anatomy of a Wildland Fire (1 of 4) Area of origin Location where fires begin Head of the fire Main or running edge of a fire Part of the fire that spreads with the greatest speed
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Anatomy of a Wildland Fire (2 of 4)
20 Anatomy of a Wildland Fire (2 of 4) Heel of the fire or the rear of the fire Side opposite the head of the fire, often close to the area of origin Finger Narrow point of fire caused by a shift in wind or a change in topography Can grow and produce a secondary direction of travel for the fire
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Anatomy of a Wildland Fire (3 of 4)
20 Anatomy of a Wildland Fire (3 of 4) Pocket A dangerous place for fire fighters because it is an area of unburned fuel surrounded on three sides by fire Island An unburned area surrounded by fire
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Anatomy of a Wildland Fire (4 of 4)
20 Anatomy of a Wildland Fire (4 of 4) Spot fire New fire that starts outside areas of the main fire Green Area of unburned fuels Black Areas that have already been burned
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Methods of Extinguishment
20 Methods of Extinguishment Cooling the fuel Removing the fuel Smothering
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Cooling a Wildland Fire
20 Cooling a Wildland Fire Water is used to cool. Backpack pump extinguishers Booster tanks from apparatus Aircraft
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Removing Fuel (1 of 2) Removal of fine fuels can be accomplished with:
20 Removing Fuel (1 of 2) Removal of fine fuels can be accomplished with: Fire broom Steel fire rakes McLeod fire tool Removal of heavier brush: Adze Pulaski axe
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20 Removing Fuel (2 of 2) Sometimes saws are used to remove heavy brush and trees from the fire. Hand saws to gasoline powered chainsaws Tractors, plows, and bulldozers Backfiring When properly set can burn an area of vegetation in front of the fire, thereby creating an area devoid of vegetation
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Removing the Oxygen (1 of 2)
20 Removing the Oxygen (1 of 2) Smothering Most commonly used when overhauling the last remnants of a wildland and ground fire Earth is often thrown on smoldering vegetation to prevent flare-ups. Not as useful during the more active phases of a fire
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Removing the Oxygen (2 of 2)
20 Removing the Oxygen (2 of 2) Compressed air foam systems (CAFS) Combines foam concentrate, water, and compressed air to produce a foam Sticks to vegetation and structures in the fire’s path When the heat of the fire reaches the foam, it absorbs the heat and breaks down the foam. This cools the fuel.
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20 Types of Attacks Direct attack Indirect attack
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20 Direct Attacks Mounted by containing and extinguishing the fire at its burning edge Fire fighters might smother the fire with dirt, use hoses to apply water to cool the fire, or remove fuel. Dangerous to fire fighters because they must work in smoke and heat close to the fire
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20 Indirect Attacks Most often used for large fires that are too dangerous to approach through a direct attack Mounted by building a fire line Can be mounted using hand tools or by using mechanized machinery Most appropriate when the topography is so rough that a direct attack is dangerous or impossible
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20 Priorities of Attack IC must assess and evaluate the priorities for preserving lives and property before determining how to attack a wildland fire.
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Safety in Wildland Firefighting
20 Safety in Wildland Firefighting Fighting wildland and ground fires is hazardous duty. Shares many of the hazards of structural firefighting plus additional hazards: Driving, falls, smoke and fire, and falling trees
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Hazards of Wildland Firefighting (1 of 2)
20 Hazards of Wildland Firefighting (1 of 2) Driving in rough terrain Risk of rollover Working in rough terrain Risk of falls Burns and smoke inhalation Wear PPE Use SCBA in conditions where needed
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Hazards of Wildland Firefighting (2 of 2)
20 Hazards of Wildland Firefighting (2 of 2) Falling trees Trees of all sizes can fall with little warning. Electrical hazards Wires that drop on vegetation may ignite. Difficult to see at night and in smoky conditions
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Personal Protective Equipment
20 Personal Protective Equipment One-piece jumpsuit, or a coat, shirt, and trousers Meet the requirements of NFPA 1977 Garments should be constructed of a fire-resistant material like Nomex® Wear an approved helmet with a protective shroud, eye protection, gloves, and protective footwear. Respiratory protection Filter mask
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Fire Shelters Lifesaving piece of equipment
20 Fire Shelters Lifesaving piece of equipment Thin reflective foil layer attached to a layer of fiberglass Designed to reflect about 95% of a fire’s radiant heat for a short period of time Fire fighters use their fire shelters when unable to reach safety in time.
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Wildland Urban Interface (1 of 2)
20 Wildland Urban Interface (1 of 2) The mixing of wildland with developed areas Creates a massive problem for fire departments in many parts of the country Wildland fires regularly ignite buildings and become structure fires.
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Wildland Urban Interface (2 of 2)
20 Wildland Urban Interface (2 of 2) Wildland urban interface Explain the mixing of wildland with developed areas Area where undeveloped land with vegetative fuels is mixed with manmade structures Fires in this zone present a significant life safety hazard. Many areas do not have adequate municipal water systems.
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20 Summary (1 of 2) Wildland fires are unplanned and uncontrolled fires burning in vegetative fuel that sometimes includes structures. Fire fighters need to understand the factors that cause fire ignition and affect the growth and spread of wildland fires.
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20 Summary (2 of 2) Growth of the fire is influenced by weather factors and by the topography of the land. Assess and evaluate the priorities for preserving lives and property. The wildland urban interface creates a massive problem for fire departments.
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