Valley View Fire-Defensible Space

printed in the Kittitas County Conservation District January 2009 newletter

By Thembi Borras

In July of 2008, 11 homes and more than 1,000 acres burned. This loss happened to occur in the Park Hill community in Spokane, WA as a result of the Valley View Fire, but this loss could have occurred in any number of communities in the wildland/urban interface closer to home. The wildland/urban interface is the term used when nature and homes intersect. People are drawn to the solitude, views, privacy and beauty that living in nature brings, but when we build a home that is surrounded by forest or brush, eventually the dangers of living in nature become apparent. Fire can burn the shelter we create. Ironically, people are drawn to nature only to have to modify it to protect life and property.

A fire needs fuel, heat and oxygen to burn and an ignition source to get it started. Fuels, at least, can be manipulated to minimize the risk of loss. In fact, several homes in the path of the fire in the Park Hill community survived because their owners had created a defensible space. Seeing a house that survived next to a home that did not in a severely burned landscape is sobering.

To create a defensible space, it is important to first identify the “hot side”, which is the direction from which fires will most likely approach and is based, in part, on the prevailing wind direction in the summer, percent slope and aspect. For example, the northwest side is the “hot side” for many homes in Sky Meadows, a community located in Upper Kittitas County, because the prevailing wind direction in the summer is from the northwest and many homes sit at the break in slope to take advantage of the view of Mount Stuart. Identifying the “hot side” will help to prioritize the areas to focus on first. Sadly, the homeowners in the Park Hill community had just initiated a fire hazard reduction program but not much work had been done before the fire swept through the area. One landowner had a machine masticate the brush along his driveway beneath an overstory of ponderosa pine, but had not yet had a chance to get to the steep area below his house choked with hundreds of tiny seedlings and brush. The ponderosa pine survived, but his home did not.

In general, the area out to 200 feet is referred to as defensible space. It should incorporate both the landscape and construction Firewise principles (http://www.firewise.org/) as well as provide access for a fire truck and a safe spot for fire fighters to defend a home. The area surrounding a home can be separated into three commonly recognized zones each warranting an increasing level of attention the closer the zone is to the home. They are:

Zero to Thirty Feet (Zone 1): This is the most critical zone. Create a five foot fire-free area on all sides of all structures using non flammable landscaping materials or annuals or perennials with a high moisture content. In the balance of the zone, remove all flammable vegetation or other combustible growth and water plants and trees well or consider xeriscaping. When landscaping, consider the use of fuel breaks such as gravel, or stone paths, well-watered lawn areas, fire resistant and native plants and water features. These act as non-flammable breaks between fuel sources that can help keep a ground fire from spreading. Maintain single specimen trees, ornamental shrubbery or similar plants such that they do not form a means of transmitting a fire from them to the home or outbuildings. Prune specimen trees, so that the lowest limbs are 6 feet above the ground to as high as a pole saw can reach, but remove no more than 50% of the live crown. Go to http://www.dnr.wa.gov/htdocs/rp/stewardship/bfs/WESTERN/pruning.html, for information on how to prune and illustrations of a proper pruning cut. Also, consider staggering the distance between the ground and the height of the lowest limbs to avoid the lollipop look. Space conifer trees such that the crowns are 30 feet distant from each other. Space shrubs 10 feet apart. Remove portions of trees that extend within 10' of the outlet of any chimney or stovepipe. Remove dead or dying wood from any tree adjacent to or overhanging any building. The roof is the most vulnerable part of a house so clear the roof and gutters of leaves, needles or other dead vegetative growth. Stack firewood and locate propane tanks 30 feet from any structure and clear flammable vegetation that is within 10 feet of them.

Thirty to One Hundred Feet (Zone 2): In this area, plants should be low growing and irrigated and trees well spaced and pruned. Native understory vegetation may be retained. The minimum distance between the shrub layer and the canopy should be, at least, 4 times the height of the shrub layer. For example, if the shrub layer is 2 feet tall then the lowest limbs of the overstory trees should be 10 feet above the ground. Maintain space between shrubs at least 2 times as wide as their diameter. Clusters of two to three trees should be spaced 30 feet apart and individual trees should be spaced 20 feet apart. Prune trees as in the highest priority area.

Develop adequate access for emergency vehicles. The diameter of a turnaround should be at least 3 times the length of the vehicle. It is very important to reduce the fire hazard around access routes, especially the roads over which emergency vehicles will travel. The driveway should be at least 12 feet wide with a vertical clearance of 15 feet and preferably a slope of less than 5%.

One Hundred to Two Hundred Feet (Zone 3): The goal in this area is to thin overcrowded native plants, eliminate ladder fuels and remove any debris that will fuel a fire. Reduce the density of overstory trees so that their canopies do not touch. Ladder fuels are vegetation that connects ground vegetation to tree crowns facilitating a ground fire becoming a crown fire; a crown fire moves much more quickly. Reducing ladder fuels may be accomplished by, in part, removing suppressed and intermediate trees and pruning trees as described in the highest priority area. Treat heavy accumulations of woody debris by, for example, chipping slash piles.

Signage is important, so emergency vehicles can find the home. Accessible water is also important; check with the fire district to make sure the design of the fire hydrant is compatible with the fittings a responder would use to connect to the hydrant. The Park Hill community had hydrants, but the fittings were not compatible with that of the response team’s equipment. In addition, the hydrants were made of PVC some of which burned. Bottom line, the hydrants were useless to the firefighters.

Try to schedule fuel reduction projects to begin after Sept 1 when trees are beginning to go into dormancy when beetles are not as attracted to fresh cuts and slash.

Fire hazard reduction activities will generate slash and may generate logs. Within 100’ of the structure, slash may be end hauled, chipped or piled and burned. Slash located 100’ or more from the structure may be lopped and scattered. In most circumstances, if the fire hazard reduction activity yields less than 5,000 board feet of timber per 12 month period that will be used by the landowner, a Forest Practice Application/ Notification is not needed. Otherwise, a Forest Practice Application/ Notification must be approved by the Washington Department of Natural Resources before operations begin.

In conclusion, the Upper County, in particular, is a high risk area because, in part, there is a history of nearby wildfires, the climate is dry with a dry season lasting more than 3 months, the terrain can be steep and fuel can be abundant. To minimize the risk of losing a home in the wildland/urban interface consider implementing Firewise guidelines.

Resources include the Kittitas County Conservation District, which can be contacted at 509-925-8585, the Washington State Department of Natural Resources, the Southeast Headquarters of which can be contacted at 509-925-8510 and local fire districts. For additional guidance about how to make a home and immediate area more fire safe, go to http://www.firewise.org/ and click on resources. If time permits, consider joining the local fire district, there will be no better way to learn about the emergency response infrastructure and how to protect a property from wildfire.