Fire Hazard Mitigation & Fuel Reduction Project
The Town's Fire Hazard Mitigation and Fuel Reduction Project was a 3-year, grant-funded project that will reduce the risk of wildfire in Town-owned open spaces. The project affected approximately 60 of the Town's 259 acres of open space lands. The Town will maintain the treated areas established by the grant project in perpetuity thereafter. The project accomplished two goals:
- Reduced fuel loads and fire ladders in identified "Fire Management Areas" (FMA)
- Established the portion of 100-foot Defensible Space Zone (DSZ) within Town-owned lands, defined as the portion of the DSZ that that begins on private property and ends on Town-owned open spaces
Fire Management Areas
Fire Management Areas in Town-owned open spaces are identified as having characteristics that increase the risk of wildfire. They were identified during fuel load and fire risk assessment surveys based on criteria which included:
- Well-developed fuel ladder
- Highly flammable vegetation
- Existence of fuel load (e.g., duff, downed trees)
- Areas with steep slopes and ravines
- Hot, dry south-facing areas
- Fire spreading wind patterns
The prescribed vegetation management treatment for these areas is to reduce fire ladders and fuel loads by 25% to 33%. This is accomplished by cutting and chipping dead plants, reducing ground cover, thinning shrubs, saplings, and understory, removing invasive plant species, and limbing up adult trees to 10 feet. The removal of adult, live, healthy trees is not conducted. Dead and mortally diseased trees are felled and delimbed. Large tree trunks are left on the ground to decompose naturally and provide habitat for flora and fauna. Green waste is cut and/or chipped in place and piled into relatively small compact piles that will not represent undue fire risk but will decompose reasonably quickly. The overall project goal in these Fire Management Areas is to reduce fire ladders and fuel loads that could contribute to the spread of wildfire into residential areas.
Below is an example of a Fire Management Area before and after vegetation management treatment.
The approximate areas of Fire Management Treatment Areas are depicted in this Fire Management Project Area map. It is important to note that the actual project areas vary somewhat when the project is "field-fitted" on the ground, based on actual conditions.
Defensible Space Zones
Defensible space is essential to improve a home's chance of surviving a wildfire. Defensible space is the buffer created between a building and the grass, trees, shrubs, or wild land area that surround it. This space is needed to slow or stop the spread of wildfire and protects a home from catching fire, either from direct flame contact or radiant heat. Defensible space is also important for the protection of the firefighters that may defend the home from a fire. It is an important life, health, safety, and property protection step in wild land urban interface areas. View a flier from CALFIRE depicting a defensible space zone for more information.
Town-owned open space areas tend to be surrounded by private residential parcels. Single family homes on these parcels are often built close to the public-private property line and, in some cases, the 100-foot defensible space zone falls within Town-owned public space lands. A diagram of this is provided below.
This project will establish the defensible space zone that falls within Town-owned open space. This area falls between the dotted green line and the solid yellow line in the image above. In the illustration above, 20 feet of defensible space for Property #1 falls onto Town-owned open space, 50 feet for Property #2, and 80 feet for Property #3. In the above illustration, all of the defensible space for Property #5 is on private property. Private property owners are responsible for the maintenance of defensible space on their private property, and the Town encourages them to do so. The Town will maintain the portion of defensible space that falls onto Town-owned open space (e.g., 20 feet for Property #1).
Approximately 33% to 50% of the existing understory vegetation is removed in Defensible Space Zones that fall within Town-owned open space areas. Dead vegetation is chipped or removed, grasses will be mowed, shrubs will be thinned, and trees will be limbed up to 10 feet. Dead and mortally diseased trees are felled.
Again, it is important to note that the Town will not remove or treat any vegetation on private property as a part of this project. Establishing defensible space on private property is the responsibility of private property owners, and is strongly encouraged.
Common Vegetation Treatment Activities in Defensible Space Zones & Fire Management Areas
Vegetation treatment activities in both the Defensible Space Zones and Fire Management Areas focus on reducing the biomass of vegetation, particularly non-native vegetation, through trimming and cutting of plants and green waste chipping or removal. Most of the treatment activities (80% to 90%) concentrate on shrub and understory vegetation. Wherever feasible, native grasses, shrubs, and trees are avoided. Work is performed using hand tools and light mechanical equipment. The Town employs noise control techniques to reduce the intrusion of noise from the mechanical equipment that is used on the project. Ground disturbance is avoided and cut plant roots are left in place (to avoid unnecessary soil disruption). Any slopes that are inadvertently disturbed during work are stabilized as needed. Herbicides (glysophate) may be applied in limited situations by workers, under the supervision of a certified pest control applicator (PCA). Herbicides will only be used on invasive species. Herbicide application is limited to foliar application of low toxicity herbicides directly onto the cut stump (i.e., a cut-and-paint application method). Please see the Integrated Pest Management and Herbicide Use section below for more information.
Protection of Endangered Species Habitats, Wetlands & Riparian Areas
The Town maintains a 200-foot buffer around endangered species habitats and a 50-foot buffer around wetlands and water bodies (e.g., lakes, creeks, streams, and associated riparian areas). These sensitive habitat areas are marked each year. In the event that the Town must conduct work within sensitive habitat areas, all work is monitored by an approved biologist.
Green Waste Management
A significant amount of plant debris (referred to as green waste) is generated during vegetation management. The green waste is comprised of:
- Dead plant material, branches, and duff already present
- Cut grass and ground cover
- Cut shrubs, branches, and saplings
- Branches and logs from dead or mortally diseased trees
Green waste is processed and disposed of onsite to the extent feasible without compromising the objective to reduce fire risk and fuel load. Green waste from sources described in #1-3, above, is handled in the following manner:
- Green waste is cut or chipped.
- Logs and large branches, free of smaller branches and leaves, are cut into small pieces (no longer than six feet) and used to create small, unobtrusive stacks no larger than 3 feet high, 5 feet long, and 4 feet wide. Leaves, branches, bark, and duff are collected, chipped or shredded, and compressed into flat piles no more than 2 feet high, 5 feet long, and 5 feet wide. Piles of green waste are separated by different distances, depending on slope. The piles are created in such a manner so as to break down relatively quickly while also providing habitat for wildlife.
- Chipped green waste is dispersed where appropriate in a manner that suppresses invasive plant and weed growth and helps stabilize soil in steep terrain. In no case is chipped materials applied at a depth greater than 2 inches.
- Green waste piles are not be placed in Defensible Space Zones (and are moved to other areas within open space lands).
Green waste from sources described in #4, above, will be handled in the following manner:
- Branches and logs from dead or mortally diseased trees, particularly those that might be infected with sudden oak death, will not be chipped, and are left to decompose in place to help prevent spread of disease. Please see the section below regarding sudden oak death.
It is important to note that this is not a tree removal project. This is a fire ladder and fuel load reduction project that focuses on limbing up trees and thinning understory. Dead and/or mortally diseased trees will be felled and delimbed with the trunks left on the ground to decompose naturally. Tree saplings are cut, but the removal of native tree saplings will be avoided where feasible. Invasive tree saplings in the treatment area are removed where possible. A sapling is defined as a tree that is 4 inches in diameter at breast height (dbh).
Sudden Oak Death
Sudden Oak Death (SOD), a tree disease that affects native oaks and other native trees, is known to occur in at least two of the open space areas: Crocker Lake and Tobin Clark. SOD-infected trees are felled if the Town determines that it is essential to meeting the treatment objective of wildfire fuel reduction. The plant matter from felled SOD-infected trees is left in-place to avoid the spread of SOD. No additional treatment activities are performed within 200 feet of infected trees, and staging, parking, and work areas are located away from infected trees to the extent possible. All equipment, vehicles, and individuals are inspected upon leaving project areas for soil, leaves, twigs, and branches. Equipment and vehicles are cleaned onsite as needed to avoid spreading SOD and invasive species seed to offsite locations.
Soil Protection & Avoidance of Ground Disturbance
The Town is required by environmental regulation to avoid ground disturbance during this project in order to protect endangered species, water quality, and slope stabilization. As such, only light mechanical equipment are used in vegetated areas during this project. Further, there is no discing, grubbing, or digging in vegetated areas. Grass, shrubs, and other plants are cut at ground level. Plant roots are left in place wherever possible in order to prevent soil disturbance and erosion issues. The use of lightweight tools to remove vegetation is emphasized (e.g., weed eaters, mowers, and chainsaws). Where unintentional ground disturbance occurs, environmentally-friendly erosion control measures areimplemented.
Integrated Pest Management & Herbicide Use
Invasive saplings and brush are cut to ground and foliar level. Some of these invasive plant species are known to re-sprout from cut stumps. To fully control these species, limited, spot-application of herbicides may be used following Environmental Protection Agency (EPA) guidelines for safe application and widely accepted Integrated Pest Management Procedures.
Integrated Pest Management requires the selection of the safest, least toxic method to control the targeted pest species. For this project, the safest, least toxic pest control method was determined to be the use of a glyphosate-based herbicide. Glyphosate is an EPA Class III herbicide which is often selected by Pest Control Advisors (PCA) for use in wild land settings (with low human use levels) against the invasive plants that are found on the Town's open space lands (e.g. eucalyptus, French broom, acacia). The EPA has determined this herbicide to be non-carcinogenic and to have a relatively low toxicity to humans. It is a short-lived herbicide which rapidly binds to soil particles and therefore does not drift or migrate from the application area. For more information on glyphosate, refer to the EPA website and Wikipedia.
The Town is very aware of the possible public concern surrounding the use of herbicide and is committed to using herbicide only where it is absolutely needed to reduce and eliminate invasive species to meet the project's wildfire mitigation objects. For this project, it is used primarily to control the spread of invasive species such as French broom, acacia, and eucalyptus. The herbicide is only applied by trained professionals, under direct supervision of a certified Pest Control Advisor. The herbicide is not used within 50 feet of water bodies or when there is the risk of rain showers that could spread the herbicide to non-targeted areas.
In making its Integrated Pest Management decision about what approach to take to control invasive plant species, the Town seeks to balance the need to control the spread of highly flammable invasive species, the need to maintain the ecological health of the native plants in the open space areas, and the need to protect human health and safety (both of workers and of the public). The Town is committed to using glysophate responsibly, with licensed applicators, in the most targeted manner possible and only as needed to achieve the project objectives.
Defensible Space on Private Property
As mentioned above, all work associated with this project occurs on Town-owned open space areas, and no work associated with this project occurs on private lands. The Town strongly encourages its residents in wild land urban interface areas to establish and maintain defensible zones. Homes within 400 feet of wild land and/or open space areas are considered to be in wild land urban interface areas. Residents who would like to know if they are in a wild land urban interface area, or would like information about how to establish a defensible space zone on their private property, can view the Wild Land Urban Interface Map or contact the Town's Building Department at 650-375-7411. Residents may also reference this fire safe brochure from CALFIRE.