Oak Hill Area Fire Safe Council Firewise Risk Assessment
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Oak Hill Area Fire Safe Council Firewise Risk Assessment Updated February 19, 2020 Page 1! of 26! 1) Introduction The Firewise Communities/USA program is designed to provide an effective management approach for preserving wildland living aesthetics. The program can be tailored for adoption by any community and/or neighborhood association that is committed to ensuring its citizens maximum protection from wildland fire. The following community assessment is intended as a resource to be used by the Oak Hill Area Fire Safe Council residents for creating a wildfire safety action plan, creating a Community Wildfire Protection Plan (CWPP) and in order to become officially designated as a Firewise Community by the National Fire Protection Association (NFPA). The Oak Hill Area Fire Safe Council (OHAFSC) is an all volunteer organization that was formed in January 2019. The OHAFSC is a satellite group of the El Dorado County Fire Safe Council (EDCFSC). Fire safe councils are community-led organizations that have been formed to prevent wildfires and reduce their potential impacts on the community. These councils work to educate homeowners and residents about wildfire preparedness and how to plan for and prevent wildfires. Fire safe councils conduct numerous outreach events and implement projects such as cooperative fuel-reduction projects in neighborhoods and collaborate with other agencies to complete landscape-level vegetation management projects. The Oak Hill Area Firewise Risk Assessment was conducted between March 2019 and February, 2020. Participants included Lester Lubetkin, Alice Cantelow, Linda and Loren Azevedo, Mark and Becky Leighton, Doug and Heidi Venable, Mary Humpreys, Alice Cantelow, Mark and Carolyn Pappas, Mary Daker, Ed Krueger, Ralph and Suzie Shoemaker, Richard and Becky Miller, and Barry Callenberger. The Firewise Risk Assessment was compiled and written by Lester Lubetkin. During the assessment and development of this report, members of the group discussed how to best identify and mitigate the fire risks and safety concerns within the area while still protecting the natural resources and other features that make this area special to the residents of the Oak Hill Area Fire Safe Council. 2) Definition of the Home Ignition Zone The Oak Hill Area Fire Safe Council is located in a wildfire environment. Wildfires will happen--exclusion is not a choice. The variables in a fire scenario are when the fire will occur, and where. This assessment addresses the wildfire-related characteristics of the Oak Hill Area Fire Safe Council. It examines the area’s exposure to wildfire as it relates to ignition potential. The assessment does not focus on specific homes, but examines the community as a whole. A house burns because of its interrelationship with everything in its surrounding home ignition zone----the house and its immediate surroundings. To avoid a home ignition, a homeowner must eliminate the wildfire’s potential relationship with his/her house. This can be accomplished by interrupting the natural path a fire takes. Changing a fire’s path by clearing a home ignition zone is an easy-to-accomplish task that can result in avoiding home loss. To accomplish this, flammable items such as dead vegetation must be removed from the area immediately around the Page 2! of 26! structure to prevent flames from contacting it. Also, reducing the volume of live vegetation will affect the intensity of the wildfire as it enters the home ignition zone. Included in this assessment are observations made while visiting a sampling of the Oak Hill Area Fire Safe Council. The assessment addresses the ease with which home ignitions can occur under severe wildfire conditions and how these ignitions might be avoided within the home ignition zones of affected residents. The Oak Hill Area Fire Safe Council residents can reduce their risk of destruction during a wildfire by taking actions within their home ignition zones. This zone principally determines the potential for home ignitions during a wildland fire; it includes a house and its immediate surroundings within 100 to 150 feet. 3) Description of Fire History and Wildland Fire Characteristics that Could Threaten the Area Fire intensity and spread rate depend on the fuel type and condition (live/dead), the weather conditions prior and during ignition, and the topography. Generally the following relationships hold between the fire behavior and the fuel, weather and topography. ▪ Fine fuels ignite more easily and fire spreads faster with higher intensities than for coarser fuels. For a given fuel, the more there is and the more continuous it is, the faster the fire spreads and the higher the intensities. Fine fuels take a shorter time to burn out than coarser fuels. ▪ The weather conditions affect the moisture content of the dead and live vegetative fuels. Dead fine fuel moisture content is highly dependent on the relative humidity and the degree of sun exposure. The lower the relative humidity and the greater the sun exposure, the lower will be the fuel moisture content. Lower fuel moistures produce higher spread rates and fire intensities. ▪ Wind speed significantly influences the rate of fire spread and fire intensity. The higher the wind speed, the greater the spread rate and intensity. ▪ Topography influences fire behavior principally by the steepness of the slope. However, the configuration of the terrain such as narrow draws, saddles and so forth can also influence fire spread and intensity. In general, the steeper the slope, the higher the uphill fire spread and intensity. As can be seen in Map 1, much of the Oak Hill Area Fire Safe Council area is considered by CalFire to be in Moderate to High Fire Hazard Severity zones, except for the area south of Big Oak Road and west of Oak Hill Road, within the drainages of Martinez Creek and Squaw Hollow Creek, which is considered to be within a Very High Fire Hazard Severity zone (CalFire Fire Hazard Severity Zone Map, 2007). Between 2005 and 2009, approximately 20 fires occurred within the area covered by the OHAFSC (Maps 2 and 3). The various causes for these fires ranged from debris burning, equipment use, smoking, at least one case of arson, and power line sparking, although a number of the fires were undetermined as to cause. The largest of these fires occurred in the North Fork Cosumnes River drainage at the southern end of Oak Hill Road in 2008. Page 3! of 26! Map 1 showing the Oak Hill Area Fire Safe Council with the CalFire Fire Rank Hazard Levels. Page 4! of 26! Map 2; Fires by year Oak Hill Area FSC Map 3; Fires by ignition Oak Hill Area FSC Maps 2 and 3, the recent fire history of El Dorado County, showing the year of fires and the type or source of ignition. Page 5! of 26! Oak Hill Area FSC 2014 Sand Fire Map 4: Fire History Map of the Oak Hill Area Fire Safe Council and surrounding area A study of early historic fires within the OHAFSC area was conducted in the 1990s and found that between about 1850 and 1952, fires occurred on the order of every 2 to 18 years (Stephens, 1997). The most recent fire identified in that study occurred in 1947. The cause of the fires identified in this study could not be determined, although they appear to be associated with ranching, which was one of the primary uses of the land at that time. Prior to 1850, the area was used by Native Americans and they most likely employed fire as well. The study determined that lightening fires are uncommon in these lower elevation oak woodlands and mixed oak/conifer forests. The 4,240 acre Sand Fire in 2014 did not reach the OHAFSC area, but did burn to within about 3 miles south of its southern border (Map 4). This major wildfire event burned for more than 9 days, destroying 20 homes and 49 outbuildings. The cause of this fire was from a car parking in dry vegetation (CalFire 2014). As described in the next section, the conditions within the area of the OHAFSC are similar to those in the area of the Sand Fire. Page 6! of 26! 4) Site Description The Oak Hill Area Fire Safe Council covers a rural area in the Sierra Nevada foothills of central California, in the south-central portion of El Dorado County. Our location about 4 miles south of the town of Placerville and about 2.5 miles east of the town of Diamond Springs, along with the large number of residences makes us part of the Wildland Urban Interface. The OHAFSC includes all of the parcels accessed from the following major roads and the smaller roads that feed into these primary roads: Oak Hill Road, Hanks Exchange Road, Zandonella Road, and Pleasant Valley Road, between Big Cut Road and Cedar Ravine Road (see Map 5). Map 5, showing the Oak Hill Area Fire Safe Council, including the roads and parcel boundaries. Page 7! of 26! The OHAFSC is bordered on the west by the Logtown FSC and the Patterson Ranch FSC. The Pleasant Valley FSC lies to the northeast of the OHAFSC. Elevations within the OHAFSC range between about 1,200 and 2,600 feet above sea level. The terrain is generally gently rolling, except within the steeper canyons of the North Fork Cosumnes River, along the southern border of the OHAFSC, and along the lower portions of Squaw Hollow Creek and Martinez Creek, west of Oak Hill Road and near the western border of the OHAFSC. There are no natural lakes within the OHAFSC, however there are a number of small, man-made ponds that have served in the past for filling of helicoptor buckets for fighting fires.