Fire Suppression and Site Planning

by Nate Lowry, ASLA

Forest fire in California
Forest fire, Klamath National Forest, CA / image: photo by Matt Howard on Unsplash

As 2020 rages on, so does a record forest fire season. In the Western United States alone, over 6.6 million acres have been burned, 7,500+ structures have been destroyed, and close to 40 people have lost their lives just this year. There is mounting pressure to address what is now a yearly occurrence and landscape architects can play a key and leading role through site design.

This issue hit home for us, with some of our own employees evacuated in what were not just wilderness fires but suburban blazes as well. The problem only seems to be getting worse, with a clear need for alternative solutions to protect properties, investments, and lives moving forward.

The first way to limit exposure and susceptibility to forest fires is initial site selection and location. Americans love their freedom and often their privacy, which has led to community development right up to the fringes of nature. Local and state agencies play a huge role in where houses are sited and what codes are required to address fire danger. Do isolated or rural community developments in the West need to stop altogether, or can certain techniques and approaches be used to more safely develop these communities?

The fringes of a development are the place to start. Just as firefighters dig fire lines to redirect and control fires, can that notion be carried through to site design? Irrigated green belts are one option, preferably with native drought-tolerant trees and shrubs. Another option is a graybelt of sorts—a zone where vegetation is kept to a minimum or removed altogether with a non-combustible surfacing like aggregates or other hardscape material. The US Forest Service recommends a 200-foot buffer for moderate risk projects, 300-foot for high risk, and 400-foot for extreme risk projects. Dedicating this much land to fire suppression is not always possible, but providing any form of green/graybelt is better than doing nothing. Time is always of the essence; if an extra 10 or 20 minutes can be had through fire suppression techniques, lives will be saved. Maintenance is also vital. Where native forests exist near developments, it is imperative that understory vegetation be regularly maintained. Site access for first responders also plays a key role, with multiple access points to a community desirable for safety. It is very hard or impossible to provide 100% fire suppression, but techniques can be used to slow down or redirect fire spread and allow more time for residents and others in the area to escape.

Suburban development, Corvallis, OR / image: photo by Porter Raab on Unsplash

Tree and shrub selection in greenbelts and for individual home sites also plays a key role. Oftentimes low -growing groundcover plantings or lawn areas will reduce or redirect fire spread. And, there is quite a range of combustibility from one shrub or tree species to another. Known species with fire-retardant properties include: rockrose, ice plant, hedging roses, honeysuckles, currant, cotoneaster, coreopsis, sumacs, and broadleaf evergreens, vs. conifers. Tree spacing is key as well in fire-prone areas. Place trees so that mature canopies do not extend to each other or, even more importantly, close to a structure. Again, ground maintenance is key in these zones and it is imperative to remove dead plants, prune existing ones, and remove plant debris. Irrigation plays a key role, too, but in moderation—enough to establish plants and keep them healthy but not too much water to over-stimulate growth (and create more fuel to burn). Some good old-fashioned goats can be deployed as well, with grazing habits that naturally prune and reduce ground level vegetation.

Backyard pool layout / image: photo by Mky Moody on Unsplash

Swimming pools can also aid in firefighting if sited and installed with certain aspects. They are particularly helpful if sited between the structure and native fringes of a site and outfitted to draw/pump water from. Fencing choices can be a make-or-break scenario in whether a structure burns or not and have long been known to extend fires to the structure. CMU (Concrete Masonry Units) or other less combustible materials can be effective in limiting spread to the structure. Fires can move very quickly; non-combustible fencing provides not only a wind break at ground level but could direct a fast moving fire to more combustible areas (and away from the home). Building that deck, gazebo, or patio out of concrete or other less combustible material will also help keep fires at bay and from reaching the structure.

As this problem continues to grow more severe, some out-of-the-box thinking may be required. Do at risk communities need to get medieval and maybe surround their development or business zone with a type of moat? Can transition or greenbelt areas be designed to be even more fire-proof? Do local codes and ordinances need to be more aggressive to limit the destructiveness of wildfire events? Can horticulture or botany lead the way in the development of new 100% fire-proof fast-growing plant materials?

The destruction and displacement these fires cause is undeniable. A moat is a wild solution, but what if 10 million acres burn and 12,000 structures are lost next year? Run-of-the-mill responses and solutions are failing. There is a need for more innovation to address the problem.

Unfortunately, forest fires particularly in the Western US keep getting worse and show no signs of waning. This type of natural disaster is often overlooked until the fire is at one’s doorstep. It will be key for landscape architects moving forward to understand the fire risk a project has at the outset. It will be key for landscape architects to aggressively manage site design and material selection in fire-prone areas. It can no longer be an after-thought. The techniques listed above can be the last line of defense and a deciding factor in whether someone loses their home or business. We have all seen photos of intact houses surrounded by charred-out forest—the margin of error is small and a site design feature here or a material selection there can make all of the difference in whether a structure or life is spared or not.

Please see the September 22, 2020 issue of LAND for a compilation of fire-related resources from ASLA’s online learning webinars, blog posts, awards winners, guides, and more.

Author photo
Nate Lowry

Nate Lowry, PLA, ASLA, is a licensed landscape architect for MacKay Sposito Engineering in Federal Way, WA. He has over 16 years of experience predominantly in the Puget Sound area. He is also a City Councilmember and member of the Pierce County Regional Council planning body.

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