firebreak (394) conservation practice guidance document

Firebreak (394) Conservation Practice Guidance Document

P a g e 1 | 7 Natural Resources Conservation Service

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394_MO_GD_001_February 2020

Purpose A Firebreak will address one or more of the following.

• Reduce the spread of wildfire.• Contain prescribed burns.

Criteria for All Firebreaks • Firebreaks will be located adjacent to the planned burn unit.• Firebreaks may be temporary or permanent.• Firebreaks will consist of one or more of the following:

o Bare soilo Non-flammable materialso Blackened (burned) areaso Fire-resistant vegetation

• Firebreaks will be installed in a manner that:o Is appropriate to the site, and;o Has the least impact on soil health, water quality, wildlife habitat, sensitive sites, and

cultural resources.• Firebreaks will meet the following width requirements unless otherwise specified.

o Two-times (2 X) the height of adjacent fuels.o Minimum width of 4 feet.

Types of Firebreaks The type of firebreak is selected based on vegetation types (fuels), topography, and soil conditions.

• Natural Firebreako Includes existing terrain features such as streams, lakes, rock outcrops, cultivated land, or

other areas lacking flammable material.o Expand natural firebreaks where needed to meet minimum firebreak width. Use one of the

firebreaks types described below to widen natural firebreaks.o Do not use public roads as primary firebreaks for prescribed burns.

• Constructed Firebreak.o Expose bare soil using hand tools or tillage equipment.

Hand tools, including rakes, leaf blowers, hoes, chainsaws, and shovels, arecommonly used to construct firebreaks in wooded conditions and when linking twofirebreaks through sections that are not accessible to equipment.

• Hand constructed firebreaks will be at least 4 feet wide.• Remove all leaves, sticks, logs, and other fuels from the firebreak.

Tillage equipment and other machines can be used where sites are accessible.• Till in a manner that will incorporate organic matter.• Place constructed firebreaks on the contour when feasible.• Avoid using tillage equipment and heavy equipment on sensitive sites.

o Install water bars or similar erosion control measures as needed to minimize erosion. Referto CPS Forest Trails and Landings (Code 655) for water bar spacing.

Firebreaks are a permanent or temporary landscape feature that will stop, slow, or control the spread of fire. This guidance document presents an overview of firebreak types and their minimum requirements. For details beyond the scope of this document, contact a qualified prescribed burn planner.





• Burned Firebreak (also known as “black-line”)o Apply prescribed fire in a narrow strip to remove fuels in a controlled manner.o Follow a burn plan for installing burned firebreaks. The burn plan will specify the following

burn conditions to minimize risk of fire escape. Humidity >40% Windspeeds <10 mph Start and complete before 10:00 AM or after 3:00 PM.

o Create burned firebreaks within one week of planned prescribed burn.• Vegetated Firebreak

o Consist of planted cover that will be green at time of the burn. Cool season grasses orgrass/legume mixes are most common species used for vegetated firebreaks. Refer toCPS Conservation Cover (Code 327) for seeding specifications.

o Vegetated firebreak width will be at least 3 X height of adjacent fuels or a minimum of 15feet, whichever is greater.

o Maintain at a short height throughout the growing season to minimize thatch buildup.• Mowed Wet-Line Firebreak

o This is a two-step process that includes mowing to remove fuel from the firebreak and“wetting down” the mowed firebreak so that it will not burn.

o Mow and remove biomass from planned firebreak location. Mow to a height of < or = 4 inches. Mow to a width that is at least 3 X height of adjacent fuels or a minimum of 15

feet, whichever is greater.o Spray water along firebreak immediately prior to ignition.

Apply enough water to prohibit ignition. This may require a test fire to see howmuch water is needed.

Ensure that ample water is available.

Fuel Reduction Line – These are NOT FIREBREAKS but do improve the effectiveness offirebreaks while also improving working conditions and safety for fire crews. Fuel reduction lines will minimize fire intensity adjacent to the firebreak by reducing flame length, flame intensity, and rate of spread.

• Use fuel reduction lines when fine fuel biomass exceeds 1.5 tons per acre.• Mow next to and parallel to the firebreak, extending into the adjacent fine fuels for a minimum width

specified below.o For 1.5 – 3.0 tons per acre, fuel reduction lines will be at least 10 feet wide.o For > 3.0 tons per acre, fuel reduction lines will be at least 20 feet wide.

• Mow to reduce fuel height to < or = 12 inches.

Operation and Maintenance • Inspect all firebreaks immediately prior to burn and remove any new fuels such as recently downed

tree branches or blown leaves.• Inspect permanent firebreaks at least annually and maintain as needed.• Mow, disk, or graze vegetative firebreaks to avoid a build-up of excess litter and to control weeds.

Treatment should be timed to reduce impacts to nesting when possible.• Install and maintain erosion control measures as necessary to ensure proper function.• Access by vehicles or people will be controlled to prevent damage.• Bare ground firebreaks, which are no longer needed, will be stabilized.





Appendix A: Firebreak Images and Examples

Figure 1. Natural firebreak (waterbody)

Figure 2. Hand constructed firebreak, the preferred method on forestland.





Figure 3. Hand constructed firebreak on forestland being used for access and monitoring during fire.

Figure 4. Heavy equipment can be used to install firebreaks quickly on forestland but can negatively impact soil health, water quality, forest health, sensitive sites and cultural resources. Consider all of these factors when planning to use heavy equipment for firebreak installation on forestland.





Figure 5. Constructed firebreak in a grassland setting.

Figure 6. Constructed firebreak on a vegetated firebreak in a grassland setting.





Figure 7. Vegetated firebreak (close-mowed cool season grass).

Figure 8. Burned firebreak/black-line installed prior to grassland burn.





Figure 9. Installing a wet-line along a close-mowed vegetated firebreak. Note ignition point in the backgound.

firebreak (394) conservation practice guidance document

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