Forest Fire Behavior 101
In summer months forest fires present particular problems. While it is relatively easy to arrest their spread, it is very difficult to put them out and to contain them. Greenery overhead and on the forest floor maintains humidity, blocks direct sunlight and inhibits wind. Thus such fires normally spread slowly in the eastern forest regions. However, dry duff burns and smolders for ever, and is very difficult to wet (like dry peat) thus complete extinction is very difficult. Also old rotten stumps burn a long time and fire may burn out old dry, rotten root trails. These sometimes run underneath fire lines dug to contain the fire. Thus the fire emerges outside the fire line and burns uncontained again.
Fire Control 101
To control a forest fire, fire fighters rake and dig a control line on the forest floor down to mineral soil that won't burn. Where accessable dozers with specially designed plows are used. The objective is to surround the fire with a break of non-flammable material. Natural and man made fire barriers are also used when available. Fire lines may need to be from 1 foot to hundreds of feet wide to effectively contain a fire, depending upon fuel, terrain and weather conditions. Usually in the east they are of the 1 to 8 foot wide variety depending upon terrain and the equipment available.
When we are as dry as we are now in the summer the old slow spreading fire axiom goes out the window, and the Incident Commander(Fire Boss) must be prepared to fight a fire that behaves more like a spring or fall fire (fast moving, erratic) while retaining the the typical summer characteristics. Also, the heat and humidity affects firefighters' and equipment performance.
Water Use in Fire Control
Water often is used for suppression directly and in mop up work, and this is now another resource that will be more difficult to obtain. Typically water is used where the fire is accessible to fire trucks. Fire fighters will use retardents in the water and/or foam to stretch the water supply. Aerial drops using fixed wing aircraft or helicopters will also use retardents to stretch the water supply.
