Title: Hazardous Vegetation Abatement (HVA)
Department: Placer County Office of Emergency Services
Staff contact: Dick Simmons, 886-5306,firstname.lastname@example.org
History: Following the destructive Angora Fire in El Dorado County and Washoe Fire in eastern Placer County in the summer of 2007, the Board of Supervisors, acting at the request of the greater Tahoe community in Placer County, passed an ordinance for “Hazardous Vegetation Abatement for Unimproved Parcels” aka the “HVA Ordinance” on October 23, 2007. This was a one year “pilot” ordinance applicable only to those areas being provided fire protection by the North Tahoe Fire Protection District, Alpine Springs County Water District, Squaw Valley Public Service District, and the Northstar Community Services District. The ordinance was subsequently extended and now remains in effect through December 31, 2012.
However, after seeing or experiencing incidents in the western parts of the County such as the Sierra Fire in 2002, the Ralston Fire in 2006, the American River Complex Fires in 2008, the Gladding Fire in 2008 and the 49 Fire in 2009, many western Placer County communities expressed an interest in expanding the area to which the Ordinance is applicable. As a result, the Placer County Board of Supervisors directed the Office of Emergency Services (OES) to work with appropriate fire chiefs, assess potential impacts of the expansion of the ordinance to willing fire districts, and return to the Board with its recommendations. As a result, the Board approved expansion of the Ordinance at its Dec 14, 2010 meeting to additional, specific areas of western Placer County.
Purpose: State law for defensible space, Public Resources Code (PRC) 4291, requires owners of improved parcels (parcels having a structure) to maintain 100 feet (or to the limit of their property line) of defensible space around structures. The HVA ordinance’s purpose is to extend the enforceability of PRC 4291 beyond the property line by creating a tool that can be applied specifically to unimproved parcels (properties where no structure exists) adjacent to improved properties. The HVA Ordinance does not apply in conditions where an improved parcel is adjacent to another improved parcel. In this condition, parcel owners are encouraged to work with their neighbors to obtain necessary defensible space. The ordinance also applies only where an “extra hazardous” fire condition exists (as determined by the Fire Warden), and: (1) the owner of the improved property is significantly at risk due to fire fuels on the adjacent unimproved property, and (2) it is not possible for the owner of the improved parcel to obtain the full 100’ of defensible space required by PRC 4291.
Implementation: The HVA ordinance encourages property owners to meet the requirements of state law and Placer County Code through mutual cooperation. In addition, it emphasizes the importance of both defensible space inspection programs and public education on fire prevention. Actual enforcement of fuels reduction on an unimproved parcel is initiated either by a complaint or by a scheduled defensible space inspection. Enforcement begins after an initial inspection with an attempt to resolve the hazardous condition in an informal, cooperative manner, followed by a formal process that ends for the local fire district with its mailing of a notice-to-abate letter that allows 30-day compliance period. If abatement is not accomplished by the owner within the 30 day period, compulsory abatement may be ordered and, from that point on enforcement is by Placer County Code Enforcement. Prior to the County beginning compulsory abatement, parcel owners may request a hearing before a Board of Supervisors appointed hearing body that has final determination authority to affirm, amend or dismiss the abatement order. The ordinance also allows for a citation process which could result in a court ordered abatement.
Implementation of the requirements of the HVA Ordinance is delegated to the County Fire Warden who establishes common standards for inspections and for vegetation abatement. Additionally, the HVA Ordinance delegates to the County Fire Warden the responsibility for setting standards for reducing hazardous vegetation along roadways and along fire access easements.
Expanded Pilot: In addition to the eastern communities mentioned above, the ordinance has been expanded to the Foresthill, Loomis, and Penryn Fire Protection District areas as well as into and throughout the Placer County Fire Service Area. In addition to the unincorporated area of Colfax, this expansion incorporates the communities of Dutch Flat, Secret Town, Magra, Cape Horn, Christian Valley, North Auburn, Ophir, Iowa Hill, Horseshoe Bar, Fowler, Thermalands, Sheridan, Paige and Dry Creek.
Initial Pilot Results:
The Talmont development near Tahoe City, comprising approximately 300 acres and 545 improved and unimproved parcels, was the target of the initial year’s pilot effort. A total of 185 unimproved parcels (48 private and 137 public)* were initially inspected and 92 parcels (44 public and all 48 private) did not pass initial inspection. After being provided a formal written notification and given 30 days to comply, property owners of 27 of the 48 private and 33 of the 44 public parcels had their parcels cleared prior to or at the time of the second inspection. The remaining 21 private lots went through the full abatement process. Of those, two property owners requested formal appeals which, subsequent to a hearing by the HVA hearing body, were denied. In sum, at the conclusion of the first year’s pilot program, all 48 private lots and 126 (93 percent) of the publicly owned parcels (all unimproved) were cleared to a level consistent with the HVA Ordinance. In addition, all adjacent improved parcel owners were able to meet the 100’ defensible space requirements as defined in PRC 4291.
The Eastern Placer County Fire Chief’s Association, as the target audience of the initial pilot program, has reported that the HVA Ordinance was invaluable in gaining voluntary compliance with fire fuels reduction on unimproved parcels throughout their respective response areas. While compulsory abatement was not used in 2009 or 2010, maintaining a process that could result in abatement continued to be desirable within all communities. No costs were accrued in the County’s revolving abatement account.
* 135 of the parcels belonged to the California Tahoe Conservancy and two to the Forest Service
Appendix A to Part 4, Abatement of Hazardous Vegetation on Unimproved Parcels of Article 9.32, Fire Prevention of Chapter 9 Placer County Code
A. Purpose of Guidelines
The purpose of these guidelines is to describe fuel reduction treatments that will result in compliance with Public Resources Code (PRC) 4291(a) and (b) and with regulation 14 CCR 1299, Defensible Space. These guidelines are necessary because of recent changes to PRC 4291 that expand the defensible space clearance requirement from 30 feet around a flammable structure to 100 feet. Defensible space is the area around a flammable structure where basic wildfire protection practices are implemented. The area is characterized by the establishment and maintenance of emergency vehicle access, emergency water reserves, street names and building identification, and fuel modification measures. The focus of these guidelines is on the fuel modification measures, meaning where vegetation is managed and maintained so that it reduces the spread and intensity of encroaching wildfires or escaping structure fires.
From a fire standpoint, the vegetation surrounding homes is fuel for a fire. Even the home itself is considered fuel. Research and experience have shown that fuel reduction around a structure increases the probability of a structure surviving a wildfire. Good defensible space allows firefighters to protect and save homes safely without unacceptable risk to their lives. Fuel reduction through vegetation management is fundamental to creating defensible space.
Fuel reduction standards (clearing requirements) to create adequate Defensible Space will be very different throughout Placer County because of the wide variation of terrain, climate conditions, and vegetation characteristics. Fire frequency and intensity of burning will vary greatly between Eastern and Western Placer County because of the differing climate and vegetation characteristics. While great variation in fuel management treatments for Defensible Space is found in the County, there are some common practices:
- Properties with greater fire hazards will require more clearing. Clearing requirements will be greater for those lands with steeper terrain, larger and denser fuels, fuels that are highly volatile, and in locations subject to frequent fires.
- Creation of Defensible Space through vegetation management usually means reducing the amount of fuel around the home, providing separation between fuels, and or reshaping retained fuels by trimming. Creation of Defensible Space can typically be done by removing fuels; removing lower limbs of trees; or reducing the height of the smaller fuels. Fuel treatment practices that will comply with State Law 4291(b) include removing dead vegetation, separating fuels from 4 feet to 40 feet (depending on conditions), and pruning lower limbs.
- In all cases, fuel reduction does not mean cutting down all trees and shrubs, or creating a bare ring of earth across the property. It does mean arranging the tree, shrubs and other fuels sources in a way that makes it difficult for fire to transfer from one fuel source to another.
- A homeowner’s clearing responsibility is limited to 100 feet away from their building or to the property line, which ever is less, and limited to their land. Adjacent property owners on improved parcels are not required to clear beyond 100 feet from their structure, but are encouraged to do so to create appropriate defensible space on a community-wide basis. Adjacent property owners with unimproved parcels are required to clear their property in accordance with Placer County Code 9.32.130.
- Fuel reduction activities that remove trees may require permits from State or local agencies. For example, trees removed for fuel reduction that are used for commercial purposes require permits from Cal Fire.
The methods used to manage fuel can be important in the safe creation of Defensible space. Care should be taken with the use of equipment when creating your defensible space zone. Internal combustion engines must have spark arresters and metal cutting blades should be used with caution to prevent starting fires during periods of high fire danger. A metal blade striking a rock can create a spark and start a fire. This is a common cause of fires during summertime. Vegetation removal can also cause soil disturbance, soil erosion, re-growth of new vegetation, and introduction of non-native invasive plants. Always keep soil disturbance to a minimum, especially on steep slopes. Erosion control techniques such as minimizing use of heavy equipment, avoiding stream or gully crossings, use of mobile equipment during dry conditions, and covering exposed disturbed soil areas will help reduce soil erosion and plant re-growth.
Fuel: Vegetative material, live or dead, which is combustible during normal summer weather. For the purposes of these guidelines, it does not include decks, woodpiles, trash, etc.
Aerial fuels: All live and dead vegetation in the forest canopy or above surface fuels, including tree branches, twigs and cones, snags, moss, and high brush. Examples include trees and large bushes.
Surface fuels: Loose surface litter on the soil surface, normally consisting of fallen leaves or needles, twigs, bark, cones, and small branches that have not yet decayed enough to lose their identity; also grasses, forbs, low and medium shrubs, tree seedlings, heavier branches and downed logs.
Reduced Fuel Zone: The area that extends out from 30 to 100 feet away from the building or structure.
Building or structure: Any structure used for support or shelter of any use or occupancy.
C. Fuel Treatment General Guidelines Compliant with 14 CCR 1299 and PRC 4291:
The following fuel treatment guidelines comply with the requirements of 14 CCR 1299 and PRC 4291.
All persons choosing the use of these guidelines to obtain compliance with CCR 1299 and PRC 4291 shall implement General Guidelines 1., 2., 3. and either 4a or 4b. as described below.
1. Maintain a firebreak by removing and clearing away all flammable vegetation and other combustible growth within 30 feet of each building or structure, with certain exceptions pursuant to PRC §4291(a).
2. Dead and dying woody surface fuels and aerial fuels within Reduced Fuel Zone shall be removed. Loose surface litter, normally consisting of fallen leaves or needles, twigs, bark, cones, and small branches, shall be permitted to a depth of 3 inches in height. This guideline is primarily intended to eliminate trees, bushes, shrubs and surface debris that are completely dead or with substantial amounts of dead branches or leaves/needles that would readily burn.
3. Down logs or stumps, when embedded in the soil, may be retained when isolated from other vegetation.
4. Within the Reduced Fuel Zone, one of the following fuel treatments (4a. or 4b.) shall be implemented. Properties with greater fire hazards will require greater clearing treatments. Combinations of the methods may be acceptable under §1299(c) as long as the intent of these guidelines is met.
4a. Reduced Fuel Zone: Separation Between Fuels When using this guideline to obtain compliance with CCR 1299 and PRC 4291 within the Reduced Fuel Zone surrounding each structure, minimum clearance between fuels will range from 4 feet to 40 feet in all directions. Clearance should be in both the horizontal and vertical directions. The clearance distance between vegetation will depend on the slope, vegetation size, vegetation type (brush, grass, trees), and other fuel characteristics (fuel compaction, chemical content etc). Properties with greater fire hazards will require greater clearing between fuels. For example, if your property is on steeper slopes or has larger sized vegetation, this justifies greater spacing between individual trees and bushes (see Plant Spacing Guidelines and Case Examples below). Grass generally should not exceed 4 inches in height. However, grass and other forbs may be maintained less than 18 inches in height above the ground when isolated from other fuels or where necessary to stabilize the soil and prevent erosion.
Clearance requirements include:
- Horizontal clearance between aerial fuels, such as the outside edge of the tree crowns or high brush. Horizontal clearance helps stop the spread of fire from one fuel to the next.
- Vertical clearance between lower limbs of aerial fuels, and the nearest surface fuels and grass/weeds. Vertical clearance removes “ladder fuels” and helps prevent a fire from moving from the smaller fuels to the taller fuels.
Plant Spacing Guidelines
Guidelines are designed to break the continuity of fuels and be used as a “rule of thumb” for achieving compliance with Regulation 14 CCR 1299.
Minimum horizontal Space from edge of one tree canopy to the edge of the next
0% to 20 % = 10 feet
20% to 40% = 20 feet
Greater than 40% = 30 feet
Minimum horizontal space between edges of shrub
0% to 20 % = 2 times the height of the shrub
20% to 40% = 4 times the height of the shrub
Greater than 40% = 6 times the height of the shrub
Vertical Space: Minimum vertical space between top of shrub and bottom of lower tree branches:
33 times the height of the shrub
Case Example of Separation between Fuels: Sierra Nevada conifer forests
Sierra Nevada mixed conifer forests are intermixed with rural housing and present a hazardous fire situation. The combination of dense vegetation, elevations with long fire seasons, and ample ignition sources related to human access and lighting, results in homes with high risk of wildfire damage. This example includes gentle slopes (less than 20%), large mature tree overstory and intermixed small to medium size brush (three to four feet in height).
Application of the guideline under 4a, would likely result in horizontal spacing between large trees of 10 feet; removal of many of the smaller trees to create vertical space between large trees and smaller trees and horizontal spacing between brush of six to eight feet (calculated by using 2 times the height of brush).
Case Example of Separation between Fuels: Oak Woodlands
Oak woodlands, the combination of oak trees and other hardwood tree species with a continuous grass ground cover, are found in much of Western Placer County. Wildfire in this setting is very common, with fire behavior dominated by rapid spread through burning grass. Given a setting of moderate slopes (between 20% and 40%), wide spacing between trees, and continuous dense grass, treatment of the grass is the primary fuel reduction concern. Application of the guideline would result in cutting grass to a maximum 4 inches in height and removing the clippings, with consideration of creating 20 feet spacing between trees.
4b. Reduced Fuel Zone: Defensible Space with Continuous Tree Canopy
A vegetation removal option is available for those wanting to retain a continuous stand of larger trees with no space between tree canopies while creating defensible space. For this guideline, within the Reduced Fuel Zone, spacing between aerial fuels is not required, such as in a stand of larger trees. In this situation
- remove all surface fuels greater than 4 inches in height;
- remove lower limbs of trees (“prune”) to at least 6 feet up to 15 feet (or the lower one third of branches for small trees). Properties with greater fire hazards, such as steeper slopes or more severe fire danger, will require pruning heights in the upper end of this range.
D. Fuel Treatment General Guidelines for Roadways
The guideline below applies to roadways determined by the County Fire Warden (or designee) to be necessary for the safe ingress and egress to the area served by the roadway or fire access easement.
Property owners shall maintain a reduced fuel zone extending 10 feet onto their property from their property line or from the shoulder of the road, whichever is greater. Guidelines 4 (a) or (b) above apply.