HomeMy WebLinkAbout1.17 Wildfire Mitigation ReportMarch 2023
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December 2023
WILDFIRE MITIGATION REPORT
Spring Valley Ranch LLC
Glenwood Springs, Colorado
2023 Update
Presented by:
White River Fire Consulting
2015 Breckenridge Drive, Berthoud CO
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INDEX OF TABLES 3
EXECUTIVE SUMMARY 5
INTRODUCTION 6
Report Objectives 6
Location 6
WILDFIRE MITIGATION 8
Wildfire mitigation Objectives 8
Current Risk Situation 8
Fire Behavior Modeling 10
Fire Behavior Inputs 11
Fuel Models and Fire Behavior 14
Fire Behavior Outputs 23
Fire Behavior Interpretation and Limitations 29
WILDFIRE MITIGATION RECOMMENDATIONS 31
Section 504 Class 1 Ignition Resistant Construction as described in the 2021 International Wildland Code 39
Section 505 Class 2 Ignition-Resistant Construction 41
APPENDIX A 45
FIRE BEHAVIOR POTENTIAL ANALYSIS METHODOLOGY 45
Purpose 45
Model Description 45
BEHAVE 46
FlamMap 46
Reference Guide 48
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Table of Contents
Table of Figures
FIGURE 1. SPRING VALLEY RANCH NEAR GLENWOOD SPRINGS, COLORADO 7
FIGURE 2. RECENT LARGE FIRE PERIMETERS MAP. 9
FIGURE 3. CONDITION CLASSES MAP. 21
FIGURE 4. FIRE BEHAVIOR MODELING. 10
FIGURE 5. PERCENT SLOPE 11
FIGURE 6. ASPECT 12
FIGURE 7. ELEVATION 13
FIGURE 8. SPRING VALLEY RANCH FUEL MODELS 15
FIGURE 9. ANNUAL GRASSES/FORBS 16
FIGURE 10. SAGE AND GRASS MIX 17
FIGURE 11. GAMBLE OAK OVER SIX FEET TALL 18
FIGURE 12. ASPEN 19
FIGURE 13. MIXED CONIFER AND DOUGLAS-FIR STANDS 20
FIGURE 14. RATE OF SPREAD PREDICTIONS (MODERATE WEATHER CONDITIONS) 23
FIGURE 15. RATE OF SPREAD PREDICTIONS (EXTREME WEATHER CONDITIONS) 24
FIGURE 16. FLAME LENGTH PREDICTIONS (MODERATE WEATHER CONDITIONS) 25
FIGURE 17. FLAME LENGTH PREDICTIONS (EXTREME WEATHER CONDITIONS) 26
FIGURE 18. CROWN FIRE (MODERATE WEATHER CONDITIONS) 27
FIGURE 19. CROWN FIRE (EXTREME WEATHER CONDITIONS) 28
FIGURE 20. DEFENSIBLE SPACE CONCEPTUAL DESIGN 31
FIGURE 21. DEFENSIBLE SPACE AND DEFENSIBLE SPACE EASEMENTS 32
FIGURE 22. ROADSIDE THINNING FUELBREAK 33
FIGURE 23. ANNUAL MOWING FUELS REDUCTION AREAS 36
FIGURE 24. EXTENDED DEFENSIBLE SPACE EASEMENTS 37
FIGURE 25. SPECIAL BUILDING CONSTRUCTION PROPERTIES 38
FIGURE 26. SPRING VALLEY RANCH HYDRANT MAP 42
FIGURE 27. FIRE BEHAVIOR FLOW CHART 45
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Table of Figures
EXECUTIVE SUMMARY
The Spring Valley Ranch Wildfire Mitigation Report Update, February 2023, has been created to
meet initial and long-range development planning goals for the built environment and open space,
to ensure ecosystem and community sustainability and to integrate directives with social goals.
Specific project goals are to:
•Reduce the risk of catastrophic wildfire.
•Provide development options for the mitigation of wildfire.
•Develop an integrated management approach that encompasses all natural communities
represented at Spring Valley Ranch.
•Provide a tool to help residents of Spring Valley Ranch understand the complexity of the
ecosystem and more effectively protect their property and lives from wildfires.
Vegetation management is needed throughout the upper montane zone of the western slope of the
Colorado Rocky Mountains to return forests and rangelands to an ecologically sustainable
condition and to reduce the potential for catastrophic wildfire and insect epidemics. Vegetative
conditions at the Spring Valley Ranch property are significantly divergent from their historic
norm. A comprehensive evaluation of wildfire hazard within Spring Valley Ranch was conducted
in 2023; findings should be integrated into the overall restoration prescriptions being developed
for the property. Project-wide vegetation restoration treatments include the maintenance of
meadows, strategic fuel breaks to reduce vegetation density primarily through selective cutting to
remove undesirable species and retention of mature healthy plants, and implementation of
prescribed burning where feasible.
Other recommended actions include the utilization of ignition resistant construction for all homes
built in the development, including IR1 construction for selected properties. This is in combination
with individual defensible space and other fuel reduction mitigation. Other infrastructure
recommendations are proposed to meet adopted code compliance.
The overall intent of this plan is to look, holistically, at the built and natural environments to
create a sustainable development that is in concert with sound ecological principles while
becoming fire resistant.
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Executive Summary
INTRODUCTION
Statement of Needs
The Spring Valley Ranch Wildfire Mitigation Report was created to meet medium and long-
range development planning goals, to mitigate the risk of wildfire, ensure that management
activities are ecologically sustainable, and to integrate these directives with social and
development preferences. This plan provides specific management direction to ensure the
sustainability of the development and serves as a management guide for open space.
Report Objectives
The three main objectives of the Spring Valley Ranch Wildfire Mitigation Report are to:
1)Provide a Wildfire Mitigation Report for development review and approval.
2)Help ensure the effectiveness of the local, wildfire first responders and County Sheriff’s
Office
3)Provide a tool for current and future residents of Spring Valley Ranch to understand the
complexity of the Spring Valley Ranch wildfire issue so that they can more effectively
manage their property in relation to this ecosystem.
Location
The proposed Spring Valley Ranch development is located approximately 20 miles southeast of
Glenwood Springs, Colorado and covers 5,237 acres (Figure 1). Spring Valley Ranch is accessed
by County Road 114 (Spring Valley Road).
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Introduction
Figure 1. Spring Valley Ranch near Glenwood Springs, Colorado
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Wildfire Mitigation Objectives
1)Mitigate the risk of severe, uncontrollable wildfires by managing surface fuels and enhancing
open meadow areas.
2)Promote responsible development through Fire Adapted Communities Concepts.
a.www.fireadapted.org
3)Develop a holistic fire management package which includes:
a.Fuels Reduction
b.Construction Techniques
c.Defensible Space
d.Access / Egress
4)Minimize impacts to soils, riparian areas and the environment throughout the mitigation
process.
Current Risk Situation
For the purposes of this report, the following definitions apply:
Risk is considered to be the likelihood of an ignition occurrence. This is primarily determined by
the fire history of the area.
Hazard is the predicted fire behavior determined through the input variables of fuels, weather
and topography run through the fire behavior software FlamMap and BehavePlus2
The majority of the study area is at high risk for wildland fires. This assessment is based on an analysis
of the following factors:
•The Spring Valley Ranch area is defined by mostly moderate and high wildfire risk by the
Colorado State Forest Atlas: Wildfire Risk Assessment Public Viewer (coloradoforestatlas.org)
•The Glenwood Springs area has a significant fire history. Major fires in the area since 1994
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Wildfire Mitigation
include the South Canyon (Storm King Mountain), Coal Seam, Spring Creek, South Grizzly,
Thompson Creek, Dotsero, Panorama, Coffee Pot, Black Mountain (West on I- 70),Center
Mountain fires and more recently the Lake Christine (2018) and Grizzly Creek (2020) (see
Figure 2). The South Canyon Fire (1994) resulted in the largest loss of life to wildland
firefighters of any fire in the western United States to that date. The Grizzley Creek Fire burned
approximately 32,000 acres as well as other incidents shown in Figure 2.
While some of this data cannot be directly extrapolated to the Spring Valley Ranch development, enough
of the same conditions exist to make a reasonable assumption of significant risk.
Figure 2. Recent Large Fire Perimeters Map
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Fire Behavior Modeling
Fire behavior modeling provides a landscape level assessment of wildland fire hazards within the project
area. Potential fire behavior was analyzed in order to determine which areas are most likely to burn and
with what intensity.
A BehavePlus2 simulation was run to compute potential fire behavior characteristics over the entire
landscape for constant weather and moisture conditions. BehavePlus2 is a nationally recognized
methodology for estimating a fire’s intensity and rate of spread given topography, fuels, and weather
conditions. In order to model potential fire behavior across the project area, GIS data layers including
elevation, slope, aspect, fuel models and canopy closure were utilized in FlamMap (see Figure 4). This
modeling procedure yields three maps: 1) rate of spread, 2) flame length and 3) crown fire activity.
These output maps illustrate the potential for fire behavior for the entire project area; they are used to
prioritize treatment areas and guide fuel treatments, which in turn reduce fire intensity. Two fire
scenarios were modeled for the property, one under moderate conditions and one under extreme
conditions.
Figure 4. Fire Behavior Modeling
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Fire Behavior Inputs
Fire behavior is dependent upon aspect, slope, elevation, canopy cover and fuel type.
Figure 5. Percent Slope
Slopes are shown here as percent (rise/run x100). Steeper slopes intensify fire behavior and thus will
contribute to a high wildfire hazard rating. Spread rate of a fire for a slope of 30% are typically double
those of flat terrain when all other influences are equal. For these and other fire behavior rationales,
many of the fuels reduction projects targeted these steeper slopes.
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Figure 6. Aspect
Aspects are shown as degrees from North ranging from 0 to 360 according to their orientation. Aspects
are influential in the type and quantity of vegetative fuels. Fuels on south facing slopes tend to be drier
and more lightly loaded than fuels on north facing slopes when all other influences are equal. Aspect
also has an influence on species dominance.
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Figure 7. Elevation
Elevations within the study area vary from approximately 6,900 feet to over 9,300 feet. As elevation
increases, fuel loading and species change. Above tree line, fuels become sparse, and the natural burn
interval is measured in centuries.
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Fuel Models and Fire Behavior
Fuel models are a set of numbers that describe fuels in terms that a fire behavior model can use. There
are seven characteristics that are used to categorize fuel models.
•Fuel Loading
•Size and Shape
•Compactness
•Horizontal Continuity
•Vertical Arrangement
•Moisture Content
•Chemical Content
The study area is represented primarily by 6 fuel models GR2 (grass) GS1,GS2, (Grass Shrub) SH7
(shrub) TU1 and TU5 (timber-understory). Each of the major fuel types present in the study area are
described below in terms of the characteristics that coincide with that fuel model. Fuel model
descriptions are taken from Scott and Burgan’s Standard Fire Behavior Fuel Models (FBFM40): A
Comprehensive Set for Use with Rothermel’s Surface Fire Spread Model4, a national standard guide to
fuel modeling.
Scott, Joe H.; Burgan, Robert E. 2005. Standard fire behavior fuel models: a comprehensive set
for use with Rothermel’s surface fire spread model. Gen. Tech. Rep. RMRS-GTR-153. Fort Collins, CO: U.S. Department of
Agriculture, Forest Service, Rocky Mountain Research Station
Vegetation for the project area may or may not be specifically listed in the description. Plant
species are only an aid to help visualize the characteristics of the model. The photos are taken from the
project area and show where the local vegetation fits in.
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Figure 8. Spring Valley Ranch Fuel Models
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FUEL MODEL GR2
Figure 9. Annual Grasses/Forbs
Characteristics
Grasslands and savanna are represented along with stubble, grass-tundra, and grass-shrub combinations.
Common Types/Species
Annual and perennial grasses are included in this fuel model.
Fire Behavior
Fire spread is governed by the fine, very porous, and continuous herbaceous fuels that have cured or are
nearly cured. Fires in this fuel model are surface fires that move rapidly through the cured grass and
associated material. Very little shrub or timber is present, generally less than one-third of the area.
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FUEL MODEL GS1 / GS2
Figure 10. Sage and Grass Mix
Characteristics
Open shrub lands and pine stands or scrub oak stands that cover one-third to two-thirds of the area may
generally fit this model; such stands may include clumps of fuels that generate higher intensities and that
may produce firebrands. Scattered sage within grasslands and some pinyon- juniper may be in this
model.
Common Types/Species
Other tree and shrub species include common and Rocky Mountain juniper, buckbrush, sage, bitter
brush, and mountain mahogany. Mountain grasses are included in this model.
Fire Behavior
Fire spread is primarily through the fine herbaceous fuels, either curing or dead. These are surface fires
where the herbaceous material, in addition to litter and dead-down stem wood from the open shrub or
timber overstory, contribute to the fire intensity.
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FUEL MODEL SH7 (Extreme Condition)
Figure 11. Gamble Oak Over Six Feet Tall
Characteristics
This model consists of stands of small diameter trees or large shrubs with continuous closed crowns.
There may be high amounts of small dead limbs retained on the lower portion of trees. There may also
be high amounts of woody and needle litter associated with the stand.
Common Types/Species
Stands of mature shrubs, six or more feet tall, such as California mixed chaparral, and Scrub Oak stands.
Fire Behavior
High rates of spread can be experienced in this model. Fire is carried through the foliage as well as the
fine live and dead woody material of tree crowns. Fire spread is also enhanced by the amount of dead
woody material on the ground.
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FUEL – TU1
Figure 12. Aspen
Characteristics
Hardwoods that have leafed out support fire in the compact litter layer. This layer is mainly needles,
leaves, and occasionally twigs because little undergrowth is present in the stand.
Amounts of needle and woody litter are also low.
Common Types/Species
Plains Cottonwood and several species of willows along riparian areas are represented here. There are
mostly streamside understory plants that do not contribute to the fire intensity.
Fire Behavior
Fires in this fuel model are slow burning, low intensity fires burning in surface fuels. Fuels are mainly
needles and woody litter. Heavier fuel loadings from old dead and down trees or branches can cause
flare-ups. Heavier fuel loads have the potential to develop crown fires in extreme burning conditions.
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FUEL MODEL TU 5
Figure 13. Mixed Conifer and Douglas-fir Stands
Characteristics
This model is represented by dense stands of over-mature Ponderosa pine, Lodgepole pine, mixed
conifer, and continuous stands of Douglas-fir. In all stand types, heavy down material is present. There is
also a large amount of dead, down woody fuels. Reproduction may be present, acting as ladder fuels.
This model includes stands of budworm killed Douglas-fir, closed stands of Ponderosa pine with large
amounts of ladder and surface fuels and stands of Lodgepole pine with heavy loadings of downed trees.
This model can occur from the foothills through the sub- alpine zone.
Common Types/Species
All types of vegetation can occur in this model, but primary species are, Douglas-fir, Ponderosa pine,
and Lodgepole pine.
Fire Behavior
Fire intensities can be moderate to extreme. Fire moves through dead, down woody material. Torching
and spotting are more frequent. Crown fires are quite possible.
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The weather inputs for FlamMap were created by using weather data collected at Rifle Remote
Automated Weather Station (RAWS). It was determined that this RAWS site provided the best option for
weather data for the project area.
Table 3. Reference Weather Used in the Fire Behavior Potential Evaluation Rifle Information
Weather observations from the Rifle (RAWS) were sorted by spread component for a ten-year
period (May to October 2000-2021) to calculate these conditions. The moderate conditions class
(16th to 89th percentile) was calculated for each variable (1 hour, 10 hour, and 100 hour fuel
moisture, woody fuel moisture, herbaceous fuel moisture, and wind speed) using Fire Family
Plus. This weather condition class most closely represents an average fire season day.
The extreme conditions class was calculated in Fire Family Plus using 97th percentile weather
data. That is to say, the weather conditions existing on the two to three most severe fire weather
days were sorted by spread component for each season for the ten-year period. It is reasonable to
assume that similar conditions may exist for at least three days of the fire season during an average
year. In fact, during extreme years, such conditions may exist for significantly longer periods.
Even these calculations may be conservative compared to observed fire behavior. The following
values were used in FlamMap:
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Latitude (dd mm ss)39 ° 30' 51 " N
Longitude (dd mm ss)107 °45 ' 26 " W
Elevation (ft.)6,120
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Average Weather Conditions
Variable Value
20ft wind speed
(upslope)
17
Herbaceous fuel
moisture (%)
4 (30)
Woody fuel moisture
(%)
70
1hr Fuel moisture 3
10hr Fuel moisture 4
100hr Fuel moisture 7
Fire Behavior Outputs
From the fire behavior analysis predictions of rate of spread and flame length are derived. The maps
graphically display the outputs of FlamMap for both moderate and extreme weather conditions.
Figure 14. Rate of Spread Predictions (Moderate Weather Conditions)
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Figure 15. Rate of Spread Predictions (Extreme Weather Conditions)
Spread rate values are generated by the FlamMap model and classified into four categories based on
standard ranges: 0-20 CPH (chains/hour), 20.1-40 CPH, 40.1-60 CPH, and greater than 60 CPH. A chain
is a logging measurement that is equal to 66 feet. One mile equals 80 chains.
1 CPH equals approximately 1 foot/minute.
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Figure 16. Flame Length Predictions (Moderate Weather Conditions)
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Figure 17. Flame Length Predictions (Extreme Weather Conditions)
Flame length values are generated by the FlamMap model and classified in the four categories based on
standard ranges: 0-4 feet, 4.1-8 feet, 8.1-12 feet and 12.1-60 feet. Flame lengths of 4 feet and less are
acceptable for direct attack by hand crews. Flame lengths of 8 feet and less are suitable for direct attack
by machinery. With flame lengths of greater than 8 feet, indirect and aerial attacks are the preferred
methods.
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Figure 18. Crown Fire (Moderate Weather Conditions)
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Figure 19. Crown Fire (Extreme Weather Conditions)
Crown fire activity values are generated by the FlamMap model and classified into four categories
based on standard ranges: active, passive, surface and not applicable. In the surface fire category, little or
no tree torching will be expected. During passive crown fire activity, isolated torching of trees or groups
of trees will be observed, and canopy runs will be limited to short distances. During active crown fire
activity, sustained runs through the canopy will be observed that may be independent of surface fire
activity.
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Fire Behavior Interpretation and Limitations
The lower elevations of the study area are dominated by shrubs and grass. The most significant factor in
fire behavior for this type of fuel is wind. Under extreme conditions, all the fuel models burn with high
intensity and great speed. In order for fire to move through the area, it needs continuous fuels. In years
with good moisture a higher fuel load of grass can be expected and as grasses cure, they can become a
problem later in the season. In dry years, or during drought conditions, the grass will be very sparse and
there will be mostly bare ground between the shrubs.
Shrubs can appear green and still burn well due to volatile oils in the leaves and bark. Shrubs will also
have dead wood that may not be seen due to the leaf canopy. Because most of the shrubs lose their
leaves in the fall, the threat for late fall and winter fires is lower. If there is good moisture in the spring,
the shrubs will not burn until much later in the summer.
Gamble oak is especially dangerous as it has a waxy coating on the leaves that promotes intense burning
under the proper conditions. Dense stands scattered throughout the central and southern portions of the
development pose the greatest threat from wildfire. Many of these stands are located below planned
home sites, making proper defensible space and ignition resistant home construction of critical
importance. The rate of spread under moderate conditions is quite fast, reaching two MPH in some
areas. Under extreme conditions speeds of one MPH or greater would be common with speeds of up to
10 MPH possible without taking into account fire spread due to spotting. Flame lengths in the oak will
generally be too intense for direct attack by hand crews. Steep slopes will also contribute to intensity.
Sage varies in its burning intensity by the age and structure of the plants. Areas that are actively browsed
will typically be very low growing, have new growth and burn less intensely. As the plant gets older and/
or not browsed, it will become decadent with much of the plant dying off and contributing to more
intense burning. Under moderate conditions, the fire could be fought by direct attack methods safely.
Under extreme conditions, fire will move rapidly through the crowns of the plants, creating spotting
problems.
Stands of mixed conifers occur in stringers and patches primarily on southwest facing slopes in the
eastern portion of the study area. Under extreme conditions this fuel model is capable of producing large
flame lengths and dangerously rapid fire spread through spotting. Torching and crown fire runs are
possible. Direct attack in this fuel model may not be possible even in moderate burning conditions and
will certainly not be possible in extreme conditions. Although this fuel model does not exist as a
continuous fuel bed in the study area, conforming defensible space and ignition resistant construction is
prescribed for all homes located in or near these fuels.
Aspen stands do not pose much threat from wildfire. They would most likely be a barrier to fire due to
the typically wet conditions existing where dominant and the generally high live fuel moistures in the
plants. Even in dry years, aspen will probably not contain enough fuel to carry the fire. Aspen also tends
to occur at the higher elevations of the study area where cooler conditions exist.
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It is recommended to clean up diseased and fallen trees in the aspen stands which if left undisturbed
could create heavy fuel loads of dead and down material.
This evaluation is a prediction of likely fire behavior given a standardized set of conditions and a single
point source ignition at every point. It does not consider cumulative impacts of increased fire intensity
over time and space. The model does not calculate the probability that a wildfire will occur. It assumes
an ignition occurrence for every cell (each 30 x 30 meter area).
Weather conditions are extremely variable and not all combinations are accounted for. These outputs are
best used for pre-planning and not as a stand-alone product for tactical planning. It is recommended that
whenever possible, fire behavior calculations be done with actual weather observations during the fire. It
is also recommended that the most current ERC values be calculated and distributed during the fire
season to be used as a guideline for fire behavior potential.
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WILDFIRE MITIGATION RECOMMENDATIONS
In response to the comprehensive analysis described above, the following elements for creating a Fire
Adapted Community are suggested.
Defensible Space
•All homes and common buildings will be required to develop and maintain defensible space.
Defensible space includes the use of
vegetative management that removes
flammable fuels from around a
structure to reduce exposure to
radiant heat. The flammable fuels
may be replaced with green lawn,
gardens, certain individually spaced
green, ornamental shrubs,
individually spaced and pruned trees,
decorative stone or other non-
flammable or flame-resistant
materials.
Although this diagram depicts defensible space in relation to trees, the same zonal approach and
general thinning standards still apply in other vegetative types.
Defensible space should be created in concert with the homeowner and builder’s design aesthetic to
create both a pleasing look and fire resistant landscape.
An aggressive program of evaluating and implementing defensible space for homes in the highest
hazard neighborhoods will do more to limit fire related property damage than any other single
recommendation in this report. For this reason, the creation and maintenance of defensible space
should be covenant controlled.
Defensible Space Easements
•All lots with a downhill exposure, significant fire hazard and adjacent to common open space will
have a Defensible Space Easements (Figure 21 yellow lines), platted, and accepted in covenants.
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Wildfire Mitigation Recommendations
Figure 20. Defensible Space Conceptual design
This area will allow homeowners to extend and maintain their defensible space beyond their
property line if an extended distance is required. This area will be covenant restricted to any
dumping or disposal of combustible materials or yard waste.
Figure 21. Defensible Space and Defensible Space Easements
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Fuel Treatments
•Fuel Breaks
Two types of fuels reduction treatments, other than defensible space will be implemented: Annual
Mowing and Roadside Thinning. Evacuation Route Enhancements will likely include fuel reduction as
well (see Figure 21, brown and orange). The intent is to reduce the intensity and rate-of-spread of the
fire. The Annual Mowing along community trails fuel breaks are located in areas where the fire behavior
is most affected by topography, prevailing winds and or continuous fuels. These areas should be
delineated as Fuels Reduction Easements on the final plat map and in the development’s covenants. On-
site evaluation will determine what form of treatment is most appropriate. These fuel reduction areas
would be maintained in addition to each individual defensible space around homes. The fuel treatments
leverage off the golf course, roads, community trails and or riparian enhancement areas to create a
landscape mosaic.
Two other forms of fuels breaks will be implemented on the property. These are in the form of Golf
Courses and Ski Runs. Both create exceptional fuel breaks and have been considered within the overall
strategic layout of the fuels reduction plan. In addition to the physical fuel reduction associated with
Golf Courses and Ski Runs, both will have irrigation/snow making capabilities. Sprinklers can be
activated during a fire and snow making equipment can also be utilized to enhance the effectiveness of
the fuel break. These elements will be preplanned in the final wildfire documentation.
• Roadside Thinning (orange in figure 21) is an essential fuels
reduction component for the egress of persons on the property during
a fire as well as access for first responders. While defensible space
implementation treats hazardous fuels close to individual structures,
broader landscape level fuel modification practices known as fuel
breaks or shaded fuel breaks are implemented on a neighborhood or
community scale. Roadside thinning will be constructed along the
roads shown in Figure 21. Once implemented, the public and
responding emergency resources will have safer, ingress and egress.
The fuel break recommendations in this report emphasize utilizing
existing and or planned roadways as an anchor for fuel modification
for several reasons. Roadside thinning is designed to interrupt the
continuity of the vegetation, creating sufficient vertical and horizontal
gaps in the fuel load to reduce fire behavior. Cross-section of a typical fuel break built in conjunction
with a road can be seen in Figure 22. The plan view (a) of the fuel break shows an example of this
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Figure 22.
Roadside Thinning Fuelbreak
thinning. The distance of the fuel break as well as distance between plants is adjusted for the height
and type of vegetation being thinned as well as slope. Roadside thinning strategies offer greater cost
efficiencies than landscape treatments with harder access. The road reduces wood and biomass
removal and therefore much less cutting per acre treated is required to achieve fuel break guidelines.
It is essential the roadside thinning be done in an aesthetically pleasing manner to ensure that the
value of the community is maintained. Final prescriptions for canopy spacing, understory
modification and overall thinning distances will be generated prior to implementation.
Although roadside thinning or roadside fuelbreaks greatly enhance the safety of both egress and
access, it is often desirable to identify “collection” point within a development. Collection point areas
are predesignated to facilitate evacuating citizens a place to collect or gather for further information on
the evacuation process. The golf course clubhouse is being considered for such an area. If a fire were to
start in the southern portion of the property, it might be desirable to evacuate the entire community.
Staging citizens at the clubhouse allows authorities to direct traffic away from approaching flames and
incoming resources. This location and its possible identification as a community collection point will
continue to be evaluated.
A number of deaths have been documented as occurring during evacuations fro WUI fires.
The factors associated with these deaths, including delayed dissemination of warnings or delays in
implementation of evacuation advice, can result in evacuees leaving areas at risk with only minutes to
spare and in turn encountering dangerous conditions in the process. New communities have the
advantage of planning for wildfire evacuation. Spring Valley Ranch should be planned with adequate
route capacity, limited density of housing in any single area and a system for accurate information
delivery to residents and visitors during an emergency.
The International Association of Fire Chiefs, Ready, Set, Go! program supports developing and
improving dialogue between the fire service and the residents they serve. The program helps
departments teach individuals who live in high-risk wildland fire areas and the WUI how to best prepare
themselves, their families and their properties against outdoor fire threats. Customizable resources allow
members to incorporate some familiarity within the program, creating increased buy-in from their local
audiences. Through the trusted voice of the fire service, the program and associated resources encourage
residents/ property owners to be Ready by taking personal responsibility and action—preparing long
before the threat of a wildland fire. RSG provides tips on creating defensible space, assembling
emergency supplies, planning escape routes and identifying safety zones. The program also encourages
those in threatened areas to Go and Act early following their Personal Wildland Fire Action Plan.
Promoting cooperation and early action not only supports the safety of community members but allows
fire and emergency response agencies to utilize their resources where they are most needed.
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These tools can be found at:
https://www.iafc.org/topics-and-tools/resources/resource/ready-set-go-program
To support community evacuation, a formal, scientific Community Wildfire Mitigation Plan (CWPP)
should be developed with an evacuation component that is in concert with the IAFC’s Ready-Set-Go
program.
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Annual Mowing - Mitigation in fuel model GS1 (Figure 23), mixed sage and grass, can often be
accomplished by a Hydro-Axe or industrial mower. Annual maintenance of the Sage may only be
needed for the first few years. After the Sage has been successfully retarded, the grass can be mowed by
more conventional means. This fuels reduction project (Figure 23) creates a “line of defense” to help
prevent a grass fire from moving into a more hazardous fuel profile, north of the fuel break line. The
project shown in Figure 23 utilizes the community trail systems as the “centerline” fuel break. The
overall intent of this area is to maintain the grasses to a height of <3” or maintain greenness.
Figure 23. Annual Mowing Fuels Reduction Areas
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Extended Defensible Space Easements
Conforming defensible space shall be installed around all homes and common buildings in the
development. Defensible space easements are in anticipation that the prescribed defensible space may
extended beyond the lot line due to slope and vegetative type predominant on the lot. This fuel
reduction can be done post construction, however over-lot thinning beyond the building envelope can be
done during the vegetation removal for the building envelope. This “first pass” of fuels reduction is
much easier before construction. Flammable vegetation and materials located wholly or partially within
the treatment areas shall be treated as follows:
•At ground level- remove flammable materials, including but not limited to, ground litter, duff and
dead or desiccated vegetation that will propagate fire.
•Thin trees and large shrubs so there are at least 10 feet between crowns. Crown separation is to be
measured from the furthest branch of one tree to the nearest branch on the next tree.
•All limbs and foliage of living trees shall be removed up to a height of 10 feet or 1/3 the height of
the tree or shrub whichever is less. Remove all ladder fuels from under the remaining trees.
Figure 24. Extended Defensible Space Easements
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Ignition Resistant Building Requirements
Universal Construction Standards
All construction within the development will be required to utilize Class 2 Ignition Resistant
Construction as per Section 505 of the 2021 International Wildland -Urban Interface Code (IWUIC
2021). The exception is that a Class “A” roof covering will be required on all structures which is more
restrictive than the Class B requirement. Class “A” roof assemblies will not be permitted.
Cedar siding and other use for cedar materials on the exterior of the structure will not be permitted.
Special Building Construction Properties
Lots identified in figure 25 represent those lots which due to their increased fire hazard require
additional wildfire mitigation in the form of ignition resistant building construction Class 1 as per
section 503 of the IWUIC 2021.
Lots were assigned to the Special Building
Construction Properties category based on the
significant presence of hazardous fuel. This fuel
model was determined to be the common
denominator in the more hazardous fire behavior
outputs of flame length, rate of spread and crown
fire potential. Over-lot thinning on these lots to
convert the fuel model from one with significant
woody components to a grass/shrub fuel would
reduce the overall hazard of the property and
require the construction to adhere only to the
universal construction standards.
Figure 25. Special Building Construction Properties
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Section 504 Class 1 Ignition Resistant Construction as described
in the 2021 International Wildland Urban Interface Code.
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504. 1 General. Class 1 ignition-resistant construction shall
be in accordance with Sections 504.2 through 504.11
504. 2 Roof covering. Roofs shall have a roof assembly that
complies with a Class A rating when tested in accordance
with ASTM E108 or UL 790. For roof coverings were the
profile allows a space between the roof covering and foot
decking, the space at the eave ends shall be firestopped to
preclude entry of flames or embers, or have one layer of 72-
pound (32.4 kg) mineral-surfaced, non perforated cap sheet
complying with ASTM D3909 installed over the
combustible decking.
2. Approved noncombustible materials.
3. Heavy timber or log wall construction.
4. Fire-retardant-treated wood on the exterior side. The
fire-retardant-treated wood shall be labeled for exterior
use and meet the requirements of Section 2303.2 of the
International Building Code.
5. Ignition-resistant materials complying with Section
503.2 on the exterior side.
Such material shall extend from the top of the foundation
to the underside of the roof sheathing.
504.5 Exterior walls. Exterior walls of buildings of
structures shall be constructed with one of the following
methods:
1. Materials approved for not less than 1-hour fire-
resistance-rated construction on the exterior side.
504.6 Underfloor enclosure. Buildings of structures shall
have underfloor areas enclosed to the ground with exterior
walls in accordance with Section 504.5.
Exception: Complete enclosure shall not be required
where the underside of exposed floors and exposed
structural columns, beams and supporting walls are
protected as required for exterior 1-hour fire-resistance-
rated construction or heavy timber construction or fire-
Retardant-treated wood. The fire-retardant-treated wood
Shall be labeled for exterior use and meet the
requirements of Section 2303.2 of the International
Building Code.
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Section 505 Class 2 Ignition-Resistant Construction
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Water Supply
As seen in the map below, created by Roaring Fork Engineering, there is an extensive fire hydrant
system proposed. Although this system is designed for structure fire suppression, hydrants can be
utilized during wildfires to refill engines and to fill large bladders know as dip tanks for helicopter
buckets to dip into and fill up. In addition to hydrants, reservoirs and ponds can provide important
water sources. A significant pond will be developed in the golf course area. The absence of overhead
obstruction, associated with this golf courses, provides and ideal environment for helicopter operations.
Hopkins Reservoir is another substantial water source available for helicopter dipping operations. In
addition to this, a dry hydrant will be installed in the reservoir to provide a remote fill site for engines
and or dip tanks. The presence of an extensive hydrant system in combination with two surface water
sources provides an excellent source of water for fire suppression.
Figure. 26. Spring Valley Ranch Hydrant Map
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Justification
It is the recommendation of this report that the Wildfire Mitigation Recommendation elements described
above be selected by the authority having jurisdiction as the best approach for new development in this
area. These recommendations provide the best balance between the critical elements of water, access,
fuels reduction and ignition resistant construction.
To mitigate the potential for a structure fire extending beyond the building into the wildland and creating
a significant event, residential 13D sprinkler systems with the appropriate volume and fire flow for each
specific structure are required.
If a 13-D system should be disabled or fail and a breach of the structure should occur, defensible space
as a fuels reduction technique, to limit fire spread from the structure to the surrounding vegetation, will
be installed. A Defensible Space Easement will be established to ensure that the proper defensible space
distances are met even beyond individual properly lines on the most critical lots.
Class “A” roof coverings will be required. This provides protection, for the most critical area of the
house, from ember generation in the event of a wildland fire. The restrictions on the use of Cedar siding
and other exterior Cedar projects will help protect all structures from surface fire ignition.
From a wildfire perspective, spectrums of solutions for the development are offered. Including
geographic fuel breaks adjacent to neighborhoods and structures to reduce the rate of spread and
intensity of an encroaching wildfire. Fuel breaks in combination with defensible space are the best
solution to keep direct radiant heat and flame contact from igniting structures.
The water supply configuration is sufficient for structure protection and wildfire suppression. In most
jurisdictions throughout the United States, it is taught and recommended that engines do not hook up to
water sources other than to fill their tanks. Mobility is the key to fire suppression in the wildland urban
interface. Ample fill sites (pressurized hydrants) will be available.
Access standards will adhere to the 2020 UWIC. This code specifies reasonable and practical access
standards for the UWI, not the overly restrictive requirements of the Uniform Fire Code (UFC) which
were developed for an urban application. Often meeting UFC standards for access in rural areas creates
unnecessary and undesirable resource damage. The UWIC access standards are sufficient for fire
department access and egress while balancing the need for responsible land development.
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For these reasons, this report recommends the above stated elements be utilized to provide the most
efficient and effective approach for responsible development for the Spring Valley Ranch Project.
Post Treatment Hazard Conditions
The current wildfire hazard on the property is very diverse and ranges from areas of low hazard (low
elevation grasslands) to very high hazard in the steep mixed conifer stands. The proposed mitigation
plan is a three pronged approach to reducing the impacts of wildfire. The approach includes landscape
scale fuels reduction, home hardening along with defensible space and planned infrastructure including
access, egress, water supply and evacuation. The goal is to create a fire-adapted community that can
reduce the overall impacts to the local ecologically, the built environment and human life.
One of the goals of landscape fuels reduction is to convert the existing fuel model (vegetation type or
classification) to a less hazardous fuel model. Pre and post fuel models can be run through fire behavior
analysis to provide a description of the changes that occur in rate of spread, flame length, intensity and
other modeled characteristics, post treatment. Existing fire behavior outputs can be seen starting on
page 23 of this report. Runing a hypothetical, post treatment fire behavior map would only show the
specific treatment area reduction in fire behavior, which can be thought of as a reduction in severity or
hazard. If the plan was to treat every acre of high hazard landscape, then the modeling would be
informative. The plan, however, is to treat very specific, very strategic areas that have the highest
impact on life safety and property conservation. This is done to help maintain the ecological integrity of
the landscape and not conduct a wholesale vegetative conversion across the entire property. There are
sound ecological, social and financial reasons for not taking that approach. Achieving a Fire Adapted
Community is possible while maintaining the ecological, social and monetary goals of the development.
The proposed mitigation in this plan was designed with a wholistic approach with life safety being the
first consideration, property conservation second and incident stabilization the third goal. It would not
be appropriate to state a quantifiable reduction in hazard, post plan implementation, as many elements of
the plan do not have, as of yet, a scientifically supported and quantifiable definition of the mitigating
effects post treatment. For instance, there are no accepted and clear definitions of the reduction in
hazard (low, moderate, high, very high) if a home has conducted home hardening techniques and
defensible space. Unfortunately, even a purpose built home, designed to resist wildfire, can easily burn
if the owner leaves a window or garage door open, completely negating the fire mitigation efforts. Each
mitigation technique proposed in this plan are known and accepted techniques for reducing structure loss
and enhancing life safety, they are complementary to each other, having a synergistic effect. However it
is not possible to quantify an objective reduction in overall hazard and risk.
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Purpose
The purpose of this appendix is to describe the methodology used to evaluate the threat represented by
physical hazards, such as fuels, weather, and topography, to values-at-risk in the study area by modeling
their effects on fire behavior potential.
Model Description
Figure 27. Fire Behavior Flow Chart
The fire behavior potential analysis represents a relative ranking of locations based upon fire behavior
predicted by the model. The model inputs include aspect, slope, elevation, canopy cover, fuel type,
canopy bulk density, canopy base height and stand height. The model outputs are determined using
FlamMap5 which combines surface fire predictions with the potential for crown fire development.
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Appendix A
Fire Behavior Potential Analysis
Calculations for surface fire predictions (rate of spread and flame length) are based on the USDA Forest
Service's BEHAVE6 model.
5 Mark Finney, Stuart Brittain and Rob Seli., The Joint Fire Sciences Program of the Rocky Mountain Research Station
(USDA Forest Service, Missoula, Montana), the Bureau of Land Management and Systems for
BEHAVE
The BEHAVE fire behavior prediction and fuel modeling system was utilized to determine surface fire
behavior estimates for this study. BEHAVE is a nationally recognized set of calculations used to
estimate a surface fire’s intensity and rate of spread given certain conditions of topography, fuels and
weather. The BEHAVE modeling system has been used for a variety of applications including prediction
of an ongoing fire, prescribed fire planning, fuel hazard assessment, initial attack dispatch and fire
prevention planning and training. Predictions of wildland fire behavior are made for a single point in
time and space given simple user-defined fuels, weather and topography. Requested values depend on
the modeling choices made by the user.
Assumptions of BEHAVE:
•Fire is predicted at the flaming front
•Fire is free burning
•Behavior is heavily weighted towards the fine fuels
•Continuous and uniform fuels
•Surface fires
FlamMap
Anchor Point uses FlamMap to evaluate the potential fire conditions in the study area. The Spring
Valley Ranch development encompasses approximately 5,237 acres (8.2 square miles). The study area
for the fire behavior analysis includes the development and a buffer of approximately 804.6 meters (1/2
mile) in all directions broken down into 30-meter (M) grids. Using existing vector and raster spatial data
and field data, ArcGIS spatial analysis capabilities are utilized to calculate model inputs for each 30-
meter square (MSq) grid. These values are input into FlamMap, along with reference weather and fuel
moisture (long-term weather observations statistically calculated from the Rifle Remote Automated
Weather Station information). The outputs of FlamMap include the estimated Rate of Spread (ROS)
(from BEHAVE), Flame Length (FL) (from BEHAVE) and Crown Fire Activity. The model computes
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these values for each grid cell in the study area.
This evaluation is a prediction of likely fire behavior given a standardized set of conditions and a single
point source ignition at every point. It does not consider cumulative impacts of increased fire intensity
over time and space. The model does not calculate the probability that a wildfire will occur. It assumes
an ignition occurrence for every cell (a 30 x 30-meter area).
Weather conditions are extremely variable and not all combinations are accounted for. These outputs are
best used for pre-planning and not as a stand-alone product for tactical planning. It is recommended that
whenever possible, fire behavior calculations be done with actual weather observations during the fire. It
is also recommended that the most current ERC values be calculated and distributed during the fire
season to be used as a guideline for fire behavior potential.
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Construction in Spring Valley Ranch should be required to follow Ignition Resistant Constructing Class
I standards as defined in the 2020 ICC Wildland Urban Interface Code. These construction techniques,
in combination with fuels reduction on both the landscape and home- site level, should create a
condition where developed property would have a low-to-moderate impact from a moderate intensity
wildfire. Additionally, other improvements could be made to further ensure protection from fire. Some
of these elements are detailed in these publications from the Colorado State Forest Service:
•Home Ignition Zone Guide - 2021_CSFS_HIZGuide_Web.pdf (colostate.edu)
•6.303, Fire-Resistant Landscaping - 06303.pdf (colostate.edu)
•6.305, FireWise Plant Materials - 06305.pdf (colostate.edu)
•6.306, Grass Seed Mixes to Reduce Wildfire Hazard - 06306.pdf (colostate.edu)
•Wildfire and Insurance -2021-Wildfire-and-Insurance-Brochure-1.pdf (colostate.edu)
•Protecting Your Home from Wildfire: Creating-Wildfire-Defensible-Zones.pdf (landcan.org)
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Appendix B
Reference Guide