Date: Fri, 17 Nov 2006 10:35:07 -0700 To: Jack Cohen From: Jeff Juel Subject: Re: Cohen and Butler Cc: Bcc: Matthew_Koehler, Jake_Kreilick X-Attachments: Thank you very much, -jEFF Jeff-- The principal article is: Butler, B.W.; Cohen, J.D. 1998. Firefighter safety zones: a theoretical modle based on radiative heating. International Journal of Wildland Fire 8(2):73-77. A follow-up management article was also published with the firefighter rule of thumb: Butler B.W.; Cohen, J.D. 1998. Firefighter safety zones: how big is big enough? Fire Management Notes 58(1):13-16. During supression operations a safety zone is typically an area clear of continuous fuels, naturally occurring or human produced. If the safety zone has to be mechanically produced, then complete clearing is the fastest most practical method but typically results in significant undesirable site disturbance. After our safety zone research it became apparent that safety zones were much larger than traditionally considered and this has modified engagement tactics during operations. Given the preparation time, mechanical fuel reduction over limited areas, i.e. thinning the stand, pruning trees and removing the branch litter, can effectively prevent continuous crown fire spread within the treated area. Fire spread can occur on the surface but with much lower intensities and the remaining tree crowns significantly block radiation from high intensity fires burning beyond the thinned area. Hope this helps. Cheers-- Jack ----------------------------- Jack D. Cohen Research Physical Scientist RMRS-Fire Sciences Laboratory 5775 W. US Highway 10, Missoula, MT 59808 406-329-4821 (fax) 406-329-4825 jcohen@fs.fed.us "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." Richard P. Feynman Natural disasters only happen to those that define them, for nature cherishes equally with a gentle spring rain and with an asteroid impact. ------------------------------ ΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ Jeff JuelΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ To Jack Cohen ΚΚΚΚΚΚ 11/16/2006 03:38 cc PMΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ Subject Re: Cohen and ButlerΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ ΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ ΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ ΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ ΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ ΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ ΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚ Jakc, Thanks for responding. I've been involved with collaborative groups who are trying to deal with fire hazards and risks, and one of my group's goals in these collaboratives is to see that we don't overreach to the point that forests are too expensively (ecology and economy) treated far more than needed. I'm wondering which research article(s) you can cite or offer, when you said: Our current firefighter safety zone recommendations (based on the research of Butler and I) suggest a distance of 4 times the expected flame length between a person in the open and the flame front. Given several locations along the road of 50-80 ft tree canopies (with flame lengths 1.5 times the canopy height or 75-120 ft) that suggests 300-480 ft of clearance from all crown fire sources. Again, thanks for any information you can offer. Sincerely, -Jeff Juel Jeff-- Thank you for inquiring. The problem with the main Boulder road is that it is too long, too narrow, too rough, and has one-lane bridges. Without modification, the main Boulder road is not an adequate escape route. I advised that an appropriate mitigation to the life safety problem would be to create several safety zones along the corridor in locations of already existing opportunities that would be modified and maintained, e.g. the church camps--buildings and open areas. These "safety zones" would then require short travel distances of the road from unsafe locations. My advice also included fuel reduction along the road, particularly in those locations of closed canopy conifer forest that would potentially generate high intensity crown fire. This is for the life safety of those potentially on the road during adjacent burning. Our current firefighter safety zone recommendations (based on the research of Butler and I) suggest a distance of 4 times the expected flame length between a person in the open and the flame front. Given several locations along the road of 50-80 ft tree canopies (with flame lengths 1.5 times the canopy height or 75-120 ft) that suggests 300-480 ft of clearance from all crown fire sources. From what we have learned recently about crown fire potential, I recommended that the forest be thinned and pruned (w/ debris removed) to increase the horizontal and vertical spacing in the canopy and thereby virtually eliminate the crown fire spread potential at those locations. This will reduce the fire intensities to those produced by surface litter--a fire intensity much more compatible with human survival if entrapped while driving the road. In addition, these fuel reduction areas in conjunction with existing conifer canopy discontinuities (e.g. meadows, hardwood groves, and the residential development) provide a significant disruption to continuous high intensity fire spread through the main Boulder River riparian zone/corridor. Although I've exclusively addressed the life safety aspects of my recommendations, a principal motivation for my recommendations in the main Boulder regards the need for ecological fire occurrence. My years of attention to the wildland-urban fire issue and our agencies automatic suppression response in residential areas perceived as threatened by wildfire suggest to me that there is virtually no chance that ecologically significant fire will occur in the wilderness area surrounding the main Boulder--unless it's under conditions that defy our ability to control. Thus as we saw last summer, largely the only ecologically significant wildland fires that occur, occur extensively under severe conditions. There is nothing in what we know about historical fire occurrence, weather occurrence, or fire behavior that suggests that these extended severe conditions are the only times when the stand replacement cover types burn. This in turn suggests that we have significantly altered fire as an ecological factor in the main Boulder ecosystems. Given the current threat of wildfire to life and property in the main Boulder, what are the chances of having ecological fire occur in the wilderness area?! I think none--no chance! The ecologically significant fire occurrence will be as it occurred this past summer, extensive under severe conditions. I am motivated to reduce our material and our cultural incompatibilities with wildland fire so ecological fire can occur over its full range of conditions even in the stand replacement cover types of the Absaroka-Beartooth. But that's not likely unless we get our inhabited areas compatible with wildland fires. Cheers-- Jack ----------------------------- Jack D. Cohen Research Physical Scientist RMRS-Fire Sciences Laboratory 5775 W. US Highway 10, Missoula, MT 59808 406-329-4821 (fax) 406-329-4825 jcohen@fs.fed.us "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." Richard P. Feynman Natural disasters only happen to those that define them, for nature cherishes equally with a gentle spring rain and with an asteroid impact. ------------------------------ Jeff Juel To jcohen@fs.fed.us 10/31/2006 04:46 cc PM Subject Cohen and Butler Jack, In a 2005 report you prepared for the Forest Service with Bret Butler, concerning fuel conditions in the Boulder River drainge, Gallatin National Forest, I read where you explain the concept of "escape routes" along which residents can move to safety during wildland fire events. I wonder if you have something that explains in more detail your opinion on how wide such escape routes must be, and what sort of fuel conditions along those corridors would be safe. Thanks for your assistance. Sincerely, -- /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\^^^/\^^^/\^^^/\^^/\^^/\^^^^^===^^^=========== Jeff Juel, Ecosystem Defense Director WildWest Institute P.O. Box 7998 Missoula, MT 59807 (406) 728-5733 (406) 728-5779 fax mailto:jeffjuel@wildrockies.org The WildWest Institute was formed in April 2006 through a merger of the Native Forest Network and Ecology Center. Please check out our website at: http://www.wildwestinstitute.org "Process Predicament" - When politics pollutes public participation. -- /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\^^^/\^^^/\^^^/\^^/\^^/\^^^^^===^^^=========== Jeff Juel, Ecosystem Defense Director WildWest Institute P.O. Box 7998 Missoula, MT 59807 (406) 728-5733 (406) 728-5779 fax mailto:jeffjuel@wildrockies.org The WildWest Institute was formed in April 2006 through a merger of the Native Forest Network and Ecology Center. Please check out our website at: http://www.wildwestinstitute.org "Process Predicament" - When politics pollutes public participation. -- /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\^^^/\^^^/\^^^/\^^/\^^/\^^^^^===^^^=========== Jeff Juel, Ecosystem Defense Director WildWest Institute P.O. Box 7998 Missoula, MT 59807 (406) 728-5733 (406) 728-5779 fax mailto:jeffjuel@wildrockies.org The WildWest Institute was formed in April 2006 through a merger of the Native Forest Network and Ecology Center. Please check out our website at: http://www.wildwestinstitute.org "Process Predicament" - When politics pollutes public participation.