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Fire Hazard Mitigation and Fuel Reduction Project

The Town's Fire Hazard Mitigation and Fuel Reduction Project is a three year, grant funded project that will reduce the risk of wildfire in Town owned open spaces. The project will affect approximately 88 of the Town’s 259 acres of open space lands. The majority of initial vegetation treatment in the approximately 88 acres are expected to occur in year one, and retreatment of the same areas are expected to occur in years two and three. The Town will maintain the treated areas in perpetuity thereafter. The Project is designed to accomplish two goals:

  1. Reduce fuel loads and fire ladders in identified “Fire Management Areas” (FMA)
  2. Establish 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.

Total Acres of Town-Owned Open Spaces   259
Estimated Total Acres of FMAs to be Treated   42
Estimated Total Acres of DSZs to be Treated   46

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 Southern Facing Areas
  • Fire Spreading Wind Patterns

The prescribed vegetation management treatment for these areas is to reduce fire ladders and fuel loads. The project will reduce fuel loads in Fire Management Areas by 25% to 33%. This will be 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 anticipated as a part of this project. Dead and mortally diseased trees will be felled and delimbed. Large tree trunks will be left on the ground to decompose naturally and provide habitat for flora and fauna. Green waste will be cut and/or chipped in place and piled into relatively small compact piles that will not represent undo 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.

Approximately 46 acres of Fire Management Areas will be treated as part of this project. 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 may vary somewhat when the project is “field-fitted” on the ground, based on actual conditions when work begins.

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 flyer from CALFIRE depicting a defensible space zone.

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” 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 thirty-three to fifty percent of the existing understory vegetation will be removed in Defensible Space Zones that fall within Town-owned open space areas. Dead vegetation will be chipped or removed, grasses will be mowed, shrubs thinned, and trees and limbed up to 10 feet. Dead and mortally diseased trees will be felled. Approximately 42 acres of defensible space area that falls within Town-owned open spaces would be treated.

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 and Fire Management Areas


Vegetation treatment activities in both the Defensible Space Zones and Fire Management Areas would 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 percent) would concentrate on shrub and understory vegetation. Wherever feasible, native grasses, shrubs and trees will be avoided. Work will be performed using both hand tools and light mechanical equipment. The Town will employ noise control techniques to reduce the intrusion of noise from the mechanical equipment that will be used to implement the proposed project. Ground disturbance will be avoided and cut plant roots will be left in place (to avoid unnecessary soil disruption). Any slopes that are inadvertently disturbed during this project will be 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 will be limited to spot application of low toxicity herbicides directly onto the cut stump  (i.e., a cut-and-paint application method). No widespread foliar herbicide spraying application would occur. Please see the Integrated Pest Management and Herbicide Use section below for more information.

Protection of Endangered Species Habitats, Wetlands and and Riparian Areas

The Town will maintain 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) during work on this project. These sensitive habitat areas will be marked before start of the project, and the Town intends to avoid work within these sensitive habitat areas as much as possible. In the event that the Town must conduct work within sensitive habitat areas, all work will be monitored by a U.S. Fish and Wildlife approved biologist. 

Green Waste Management

A significant amount of plant debris (referred to as green waste) will be generated by this project. The green waste will be comprised of:

  1. Dead plant material, branches and duff already present;
  2. Cut grass and ground cover;
  3. Cut shrubs, branches and  saplings; and
  4. Branches and logs from dead or mortally diseased trees.

Green waste would be 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, will be handled in the following manner:

  1. Green waste will be cut or chipped.
  2. Logs and large branches, free of smaller branches and leaves, will be 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 would be 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 will be separated by different distances, depending on slope. The piles will be created in such a manner so as to break down relatively quickly while also providing habitat for wildlife.
  3. Chipped green waste would be dispersed where and as appropriate, and in a manner that suppresses invasive plant and weed growth and helps stabilize soil in steep terrain. In no case will chipped materials be applied at a depth greater than 2”.
  4. Green waste piles will not be placed in Defensible Space Zones (and will be moved to other areas within open Space lands).

Green waste from sources described in #4, above, will be handled in the following manner:

  1. Branches and logs from dead or mortally diseased trees, particularly those that might be infected with sudden oak death, will not be chipped, and will be left to decompose in place to help prevent spread of disease. Please see the section below regarding sudden oak death.

Trees

It is important to note that this is not a tree removal project. The removal of live, adult trees is not anticipated as part of this project. This is a fire ladder and fuel load reduction project that will focus on limbing up trees and thinning understory. Dead and/or mortally diseased trees will be felled, delimbed and the trunks left on the ground to decompose naturally. Tree saplings will be cut, but the removal of native tree saplings will be avoided where feasible. Invasive tree saplings in the treatment area will be removed where possible. A sapling is defined as a tree that is 4” diameter at breast height (dbh).

Sudden Oak Death (SOD)

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 would be 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 would be left in-place to avoid the spread of SOD. No additional treatment activities would be performed within 200 feet of infected trees, and staging, parking, and work areas would be located away from infected trees to the extent possible. All equipment, vehicles, and individuals would be inspected upon leaving project areas for soil, leaves, twigs and branches. Equipment and vehicles would be cleaned onsite as needed to avoid spreading SOD and invasive species seed to offsite locations.

Soil Protection and the 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 will be used in vegetated areas during this project. Further, there will be no discing, grubbing or digging in vegetated areas. Grass, shrubs and other plants will be cut at ground level. Plant roots will be left in place wherever possible in order to prevent soil disturbance and erosion issues. The use of light-weight tools to remove vegetation will be emphasized (e.g., weed eaters, mowers and chainsaws). Where unintentional ground disturbance occurs, environmentally friendly erosion control measures will be implemented.

Integrated Pest Management and Herbicide Use

Since this project is not expected to result in ground disturbance, invasive saplings and brush will be cut to ground 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, applied using a cut and paint (spot) application. Glyphosate is a EPA Class III herbicide which is often selected by Pest Control Advisor's (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 http://www.epa.gov/oppsrrd1/REDs/factsheets/0178fact.pdf  and to http://en.wikipedia.org/wiki/Glyphosate.  

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 will be used primarily to control the spread of invasive species such as French broom, acacia, and eucalyptus. The herbicide will only be applied by trained professionals, under direct supervision of a certified Pest Control Advisor. The herbicide will not be 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 has sought 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 projects objectives.

Aesthetic and Sight Lines

This project will result in noticeable changes in the Town’s open space areas.  Vegetation in 88 of the approximately 259 acres of Town-owned open space will receive treatment. However, this is not a tree removal project. The removal of adult, live, healthy trees is not anticipated as a part of this project. Tree branches will be limbed up to ten feet in treatment areas, but live trees will not be removed. The project is intended to focus on the thinning of brush and understory vegetation. Therefore, the Town anticipates that most residents used to sight screening from trees in Town-owned open spaces should not see a dramatic change.  Some residents looking down on open spaces from above (e.g., residents with homes built on hills) will notice that vegetation in Town owned open spaces has been thinned in certain areas. This will be particularly true in Town owned open space areas that are heavily vegetated with brush and chaparral. This cannot be avoided. However, the Town is committed to thinning brush and shrub in a way that balances aesthetics with wild fire prevention effectiveness. Shrub and brush thinning will be accomplished by creating “mosaics”, which will create a pleasing pattern of shrubs and grasslands that will help reduce the risk of wildfire and create a diverse and healthy habitat for wildlife.

Defensible Space on Private Property

As mentioned above, all work associated with this project will occur on Town-owned open space areas, and no work associated with this project will occur 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 the following fire safe documents.

Project Timeline

The proposed project is a three year project. The Town proposes to begin work on the project beginning August – October 2013. Project work will take place between May and October in 2014 and 2015. The Town will maintain the treated areas on an annual, as needed basis thereafter.


The Town of Hillsborough 1600 Floribunda Avenue, Hillsborough, CA 94010 (650) 375-7400
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