Brush and Grass Fires
TWELVE YEARS ago may or may not be a time in the distant past. For many residents of Berkeley, Cal., it is but a short period, for they can recall with all the harrowing details, September 17, 1923. On that day the city lost 584 buildings, and thirty others were seriously damaged, all because a brush fire from the hills three miles north of the city crept towards the city during a high wind. This $10,000,000 fire which made 4,000 persons homeless was but a small grass fire at the start, but within two hours it had approached and menaced houses within Berkeley.
At one time the fire presented a total front of about 1,600 feet in width. Within the next forty minutes, burning brands which were carried by high winds, had spread the fire to a maximum width of 2,400 feet.
Most Fires Occur in the Spring
Brush and grass fires are serious problems in sections which have large undeveloped areas, and they are most common during the dry seasons. If the fire losses data for this type of conflagration were plotted, it would become readily apparent that the number of fires bears a relationship to the amount of rainfall. Yet nearly three fourths of the fires of this type occur during the months of March, April and May, even though the rainfall may be normal for that period. Dead leaves, grass and brush which are in a dry condition early in the spring are excellent material for the spread of fire, and as such material usually carpets a large area, the fire soon spreads until a very large line of attack develops. Many forest fires originate as brush and grass fires.
While much good can doubtlessly be accomplished by making the public realize the seriousness of starting fires at points where they may develop into brush, grass and forest fires, the Fire Chief as protector of his community against the ravages of fires, cannot sit idly by and wait for the educational campaign to bear fruit. He must have material and men organized so that, in the event such a fire does take place, in spite of the constant preaching of fire preventionists, the blaze will be confined to a comparatively small front, and a much smaller damage will result.
Controlling fires in the woods depends largely upon pre-fire measures that are established. Where the vegetation is thickest, fire lanes must be made which will constitute breaks for the flames should fires start. These lanes are made by cutting down trees and ploughing up the ground for a width of ten feet or more. Such breaks in the wooded area or vegetation covered ground, provide natural limits for stopping ground fires providing wind does not carry sparks over the gap. The lanes also serve as roads for moving supplies into an area where a forest-fire crew is operating.
Fighting grass and brush fires requires a proper organization and the necessary appliances. A recommendation of the Western Forestry and Conservation Association is that there should be forty per cent more tools than there are men. The Chief should form a definite crew upon whom he may rely in the event that he has a large brush or grass fire to fight. These men should be called on when it is believed that the fire is too large for his regular crew of men. In calling for assistance he should give directions for the easiest way to reach the fire so that the run will l>e made in the shortest possible time. Large crews are to be avoided. Each crew of men should not be larger than say twenty-five, or in other words it should not be larger than the department’s capacity for supervising such a group of men. Where the fire extends over a large front, several crews may be provided, rather than place all the men under one control. Under ordinary conditions the efficiency of the men decreases as the size of the crew increases.
How Fires May Be Extinguished
When engaging men for fighting brush fires it is important that the men understand and are fitted for the laborious work. Each man must understand the temporary nature of the employment, and that after the fire has been placed under control, his services will no longer be required.
Brush and grass fires may be extinguished by water, by smothering with dirt, or by beating the flames out with wet blankets, brooms or backs of shovels. Water is conceded to be the best means for putting out a fire.
Where water can be obtained it should be used, as there is no equally effective substitute. For a hot fire, the water should be spread along the fire line and not head on into the fire.
Large apparatus units have been built for carrying water to rural fires. In addition to the large tank filled with water, they carry portable extinguishers and fire pumps, and shovels, brooms and other tools for fighting brush fires. Such apparatus can only be used where the road is near the fire or where the fire lanes are large enough and in proper condition to permit the movement of so heavy a unit.
A tank when loaded with water and mounted on fire apparatus makes a heavy, mobile unit, often too great in weight for the soft ground found near brush land. Tractor type wheels distribute the apparatus load over a larger area so that the weight per square foot is reduced. One manufacturer has a device which can be placed on a wheel within ten minutes to give the apparatus the benefit of better traction over soft land, and after the device has served its purpose, it can be removed in five minutes.
Where it is impossible to have the large water tank approach the fire, water may be brought to the blaze by means of portable pumps. Small gasoline operated pumps are placed on skids constructed like a stretcher so that two men can carry the pump to a source of water. The portable unit is placed on the ground, and a suction line dropped into a nearby stream. These pumps can deliver twenty to thirty gallons of water per minute up to one hundred pounds pressure. With the use of small hose lines, water was relayed three thousand feet in fighting a fire on wooded land in an area near Sudbury, Mass.
Unlined Hose Easier to Handle
Unlined linen hose of small diameter is coming into use for stretching long lines. This type of hose is lighter than rubber lined hose, and when rolled, makes a more compact and lighter bundle for the fire-fighter to carry.
A combined tractor, water tank, and pumper, is used by Los Angeles for fighting brush fires in the moun tainous sections of the city where brush fires constitute a menace to the suburban homes. Although the speed of the unit is but three miles an hour it is capable of operating on grades as steep as sixty-two per cent. The tractor portion of the unit hauls the water tank which is capable of supplying four streams at a pressure of two hundred pounds.
Portable tanks worn on the backs of fire-fighters and equipped with hand operated pumps permit the use of water over a wide front. The tanks hold about five gallons of water, and are provided with short lengths of hose. A continuous stream can be thrown for a distance of fifty feet and although these pumps are small, they have been particularly effective in fighting brush fires. Forty portable pumps of this type have been credited with saving the town of Brentwood, Long Island, after fire had destroyed about two thousand acres of wooded land. Men carrying these portable pumps are not tied down by hose lines which must be shifted, and they can quickly move about to stop fires from starting at new points, or in wetting down ground in advance of the flames.
Draft Created by Hills
Where there is a slope in the land, there will be a tendency for a greater advance in the fire. The steeper the hill the greater will be the speed with which the fire will advance up grade. Fires tend to work up hills much more rapidly than they work down. The draft created by the fire itself is up-hill rather than down. In fighting fires on land covered by vegetation, the principle is to produce a gap between the burning material and new fuel, and to break the heat wave. Heat is an important factor, for heat radiation travels in straight lines in all directions, while that heat which rises vertically tends to dry out the leaves and start fires in the tree tops. The hotter the tire, the more material is dried out, and the more material that is dried out, the greater will he the advance of the flames.
When burning before the wind, these fires burn in a long oval, gradually broadening in area, until the tire area becomes circular. When there is little or no wind, the fire burns slowly away from the starting point with equal intensity in all directions. Side fires, or the trailing edges along either side of the main fire may develop new head fires. The hottest, fastest and most dangerous portion is that which is driven with the wind. Therefore in fighting such fires it is best to attack the head fire first, and the side and tail fires later. To control the head tires, they must be attacked from the front. The Fire Chief must determine the most vital point of attack, and often considerable work and ground may he saved by spending some time in surveying the fire, before definitely placing the numerous fire-fighting crews.
Where water is not available for fighting fires, hoes, mattocks and other tools are used to construct a workedover line not over two feet from the burning edge so as to leave as little material as possible for smouldering. Another plan, called the parallel method, consists of constructing a continuous trail from six to fifty feet in advance of fire and to burn out the intervening strip. Generally speaking, this trail should never he over fifty feet from the fire and usually not over eight to ten feet. This method makes use of a continuous trail and hackfiring.
Indirect Method of Fire-Fighting
The indirect method of fighting these fires consists of completing a continuous line at a considerable distance in advance of the fire, taking advantage of any favorable topography. Then the ground is backfired. In backfiring care must be exercised that fire-fighters are not between the two fires.
As a general rule the parallel method is used on all sectors where the fire is burning briskly. It should never be used where there is any danger of the inability to burn out all intervening material so that fires will burn clean to the edge of the fire line.
The indirect method must be considered as an emergency method to be used only in rare cases, as burning out a wide strip of country is often difficult and dangerous. Differing sectors require different methods, but even the same sector mat” require different treatment at different hours of the day.
Consfrucfing a Trail
The simple way of making a fire trail is to dig out every spark on the extreme edge of the fire and to throw back the smouldering embers into the fire. With the other methods it is necessary to make a continuous trail from one to three feet wide and to dig down to clear dirt. Small roots and rotted wood must be removed so that the fire will not be carried across the trail. The light debris consisting of needles, or duff, should be thrown to the inside or outside of the trail depending on whether such material will be of assistance in starting and scattering backfires, or whether it will form a menace by smouldering and throwing out sparks. Where there is a heavy sod, the trail can be constructed much faster with a mattock or grub hoe. Where there is a thin layer of litter on a loose sandy soil, a shovel or a heavy rake is often preferable.
No matter which method of fighting is used, some fires are apt to become established across the fire line constructed. If these new fires get away, all the laborious work spent in constructing the lines will be wasted. Therefore, in addition to having men building the fire lines, it is vital to have a patrol to detect and fight fires with the portable pumps before the fires can get away.
Brush Fires Cause Long Time Loss
When it becomes evident that the fire is under control, the Chief may discharge the extra men employed and continue fighting the fire with his regular crew. As the extra men are paid by the day or hour, this will result in a considerable saving.
As a rule grass and brush fires have not received the attention they deserve because the property value is considered small as compared with the loss of a large apartment house or office building. But while buildings may be replaced within a year or two at the most, a vegetation cover can only be made through the slow and easy processes of nature. Five, ten or even twenty years must pass to restore burned over land to something near its original condition. During the time that the land remains barren, the ground lias a negative effect on the community. It is a desolate, charred, vista for the tourist, and an indication that the community has been lax in protecting one of its greatest assets. Ground which has been burned over becomes acid ground and must be properly prepared before it is fit for raising crops.
Bare Land Starts Erosion
Ground minus vegetation is a prey for soil erosion. Small cracks start to develop in the soil as there is no binder, and these develop into serious fissures. There is a rapid run-off during periods of rain, and with the high run-off, large amounts of the valuable topsoil are taken away. Farmers know that it is the top soil which produces the crops, not the sandy, or clayey loam beneath. Barren ground also has a serious effect on the water supply of the community. As there is a high water run-off, very little water finds its way to the underground water bearing strata to replenish the flow of underground streams during dry seasons. When these streams have a reduced flow, wells run dry and great hardship is caused to those whose livelihood depend on crops and cattle.
Brush, grass and forest fires become the “Old Man of the Sea” for many years to come. Ulike industrial and residential fires, which cause an immediate loss and which can be replaced by similar or better structures, blackened and burnt-over land must be handed down as an undesirable heritage. Others must pay for many years for the fire caused perhaps through carelessness and which may have developed into conflagration size through the lack of proper fire-fighting equipment.
Therefore to avoid the serious after effects of grass and brush fires, Chiefs in communities where such fires are possible, should plan and establish an effective organization for meeting such emergencies, and the department must be provided with effective tools and apparatus for fighting such fires.