1. #1
    Junior Member

    Join Date
    Feb 2003
    Cisco, IL USA

    Default priaire grass fires

    I need information and/or videos from departments with experience in fighting native prairie grass fires. The Dept. of Natural Resources, in their great wisdom, have planned to put an 1800 acre native prairie next to a 4-H camp and along 3 miles of interstate highway in my district. We are aware of the explosive nature of these native grasses but need some additional proof of the hazards that this might create. Please post here or e-mail me cisco@firehousemail.com Thanks, Ron Weishaar, Chief, Cisco[IL]Fire Department

  2. #2
    Forum Member

    Join Date
    Oct 2000
    Gregory, SD


    Ron, While native grasses can appear to be explosive at times, the reality is that mature grass burns very quickly but has short flame lengths unless pushed by high winds. With a fuel model 3 (tall grass), 90 deg F., fuel moisture 3 percent, 15 percent RH, 20 mph winds, and 10 percent slopes (typical conditions for early July in my area) gives you a Rate of Spread (RS) of 953.4 chains/hour with 38.3 ft Flame Lenghts (FL) and 900 BTU's/square ft. While this is a scary sight and you would not want to be in front of this fire (it is moving 12 mph) a good fire break is all you would need to keep the camp safe. That fire break can be something as simple as 100 ft. of mowed, well watered, green lawn. Short grass (Fuel model 1) would have a RS of 446.5 chains/hour (a chain = 66 ft.), FL of 10.0 ft., and 103 BTU's/ square ft..

    The models I gave are typical of a native grass area for Western South Dakota that is not touched in any way (no mowing or grazing). We have <22 in. of precip in a good year so our fuel moistures will be less than yours and your wind will probably be less. Find what type of grasses (species) the DNR is planning to use. Get the weather data, (max. temp, lowest RH, max wind speed), the percent slope and aspect of the area adjacent to the camp, and have someone in your State Forestry office or someone with a fire behavior program help you with RS and FL for your situation.

    Personally I would welcome such an area next to me, especially if I got to hunt there. In the Black Hills of South Dakota, a native grass meadow is considered a good fire break around a youth camp. Atleast one camp has as their fire plan, if evacuation is impossible, to put all campers in a fire resistant structure and the grass surrounding the camp is to be burned off to protect the camp from a forest fire. The threat you tolerate is relative to the area you live in, you must decide. I am not being critical of your actions, I am just telling how it is here. You must decide what is safe for your area based on the expected fire behavior of the native grasses in your climate. I wish you the best if you continue with your fight, if your DNR is like most you will be in for a long drawn out process.

    Last edited by Bowbreaker; 02-14-2003 at 01:31 AM.

  3. #3
    Senior Member

    Join Date
    Feb 2001


    Not sure how to start. I do no for a fact that at 100 degrees with a 40 mph wind that the fire will do 40 mph across the field with flame hights around 30 feet. It all depends on the type of grass they put in. It can be dangerous but if the 4-H camp takes and keeps a good 100 yd or so mowed area (1" or so) and there should be no problem protecting the camp with standard structure pumpers put as always To save any of the grass it will take special equipment. I have 7 years experience in that type of prarie fires in grass rangeing from 1" tall and thin to 48" tall and extremly thick(not a good thing). The tall thick grass the goverment put in our area is called lovegrass if they tell you that is what they are putting in fight it all you can. This grass I have seen burn when its green after a 1" of rain hours earlier and still be hard to put out and 200 acres burn quickly. It gets up to 60" uncontrolled and on and will travel at speeds equal to the wind and in high tempratures It will create its own wind and travel at speed in excess of 50mph. If you have any more questions just let me know I do not have and videos of these fires but I will do the best I can to help with info.

    P.S. Please dont think I am talling tales I am telling the truth and I have the Scary stories to prove it.

    Hope The Info Helps

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