USING STRUCTURAL APPARATUS AT WILDLAND FIRES, PART 2
THE ENGINE COMPANY
I’nrl I. which discussed the uses of structural apparatus in direct attack at wildland fires, appeared in the February 1994 issue.
Structural fire apparatus can be used effectively in indirect attack on wildland fires. This strategy requires that there be substantial supplies of water available.
One of the most useful tactics of an indirect strategy is the creation of firebreaks and/or wetlines to contain the fire. Roads themselves often are effective firebreaks, but flaming embers can cross roads and start spot fires a substantial distance ahead of a firefront. depending on wind conditions A simple w ay to increase the effectiveness of a road firebreak is to wet the vegetation on both sides of it. Structural apparatus are capable of wetting large areas in short periods using deluge guns and minimal manpower.
Pumpers can wet down vegetation front the ground up; and ladder trucks, aerial platforms, and so forth can work from the top down. A reasonably effective wetline 200 feet deep and 400 feet long can be created with each 1,000-gallon, two-minute blitz by a pumper; it is possible for a pair of 1,000-gpm pumpers (properly supported by tankers/tenders) to create a 400-foot-wide barrier (200 feet on each side of the road) at a rate of about one mile per hour. In situations in which a 200-toot wetline is sufficient, the rate of creation should be about two mph.
Since only the largest of wildland fires have fronts exceeding two miles in width, it should be possible to create effective wetlines in advance of most fires along any accessible road with access to a large enough water supply in a matter of a couple of hours, once a sufficient force of pumpers and support tankers can be assembled. Assuming 1,000 gallons per 400 linear feet of wetline 200 feet wide, it would take approximately 28,000 gallons per mile to create a wetline 400 feet wide. To do this at a rate of one mph. it would take a tanker flow rate of 28.000 gallons per hour, or 466 gpm. Additional water supplies would be needed to rewet lines as the initial wetting evaporated and on contact with the actual firefront.
As the head of the fire burns into the wet fuel in the wetline. the advance of the firefront slows drastically, and suppression resources can be concentrated there. Once again, the high-capacity pumpers and aerials can be brought into action quickly and their flows concentrated at these critical points of contact. Wildland fires generate heat in proportion to the speed with which they move into and consume fresh fuels. The wetline slows these fires down by forcing them first to dry out the fuel in their path. This process not only requires the fire to dissipate heat in evaporating the water on the fuel and terrain ahead of it but also reduces the rate at which fresh heat is produced. Since the fire’s heat is both consumed and created at a slower pace at the wetline, less additional extinguishing agent is needed to knock down, control, and extinguish the fire at this point. Additional buffers, such as “blacklines” or backfired areas and bulldozed or hand-cut firebreaks, can be used as needed in conjunction with a wetline to control the fire. The key point is that under the right circumstances, structural apparatus can be used to create wetlines with great speed as well as provide high-volume firetlows at critical points of contact in the wildland firefighting effort.
Structural firefighting apparatus also can be employed effectively in wildland firefighting in a support function, such as in exposure protection, water supply, communications and control, and overhaul.
In wildland firefighting, exposure protection can be a stationary task (for example. protecting structures or escape routes) or a mobile task (for example, patrolling an area and extinguishing spot fires). Structural-type fire companies can perform these tasks well as long as they have sufficient water supplies and can work from roads, in such roles, the capability of a high-volume pumper to blitz spot fires with large quantities of water in a very short period and with minimal manpower can he invaluable. Structural apparatus can hit a spot fire hard, refill from a supporting tanker, turn the sceneover to wildland units, and move on to the next spot fire in minutes. Of course, when it comes to protecting structures and extinguishing structure fires, these companies simply are doing the job for which they are designed.
Structural apparatus also can provide a water supply during wildland fire operations. With their large-capacity pumps and large-diameter hose, structural pumpers can pump 1,000 gallons of water per minute at draft through their supply hose. If the supply line ends at a 1,000-gallon tanker (tender), the tanker can be filled in a little more than one minute. Highcapacity pumpers can speed up the water resupply process substantially when used properly. A series of pumpers in relay can “reduce” the distance to the water supply and increase the fill rate for tankers and other vehicles. This can increase the rate of water resupply, especially for operations taking place within a few miles of a water source. With sufficient tankers available. the only constraints on water flow at a rural fire scene become the pumping capacity at draft and the pumping capacity at the fire. Structural fire engines can provide the capacity at the draft side of the water line as well as at the fire end.
Though we’ve discussed mostly pumper use in wildland applications, remember that aerials also may prove an excellent resource. Aerial apparatus can provide a number of unique services in the support area, including serving as draft pumpers, since many aerials are equipped with a draft capability and have high-capacity pumps. They can be used for communications and control. Aerials make superb observation platforms, and they can be used to elevate the incident commander, operations officer, or other team leader to a position from which to obtain a good view of the fire scene and effectively direct or supervise operations. They can provide a high perch for radio equipment or antennas, extending the range of communications. An IC can think of aerial apparatus as movable high ground; any time or place it would be useful to occupy such “high ground,” an available aerial apparatus can provide it.
Inevitably comes the job of mop-up. Overhaul generally has to be performed by hand, whether done in a city building or a countryforest. Someone has to turn the fire over and make sure it’s out. However, until a wildland fire area can be worked over by mop-up crews, it is usually necessary to patrol the perimeter of the fire area and keep it wet. This is another job for the high pumping capacity of structural firefighting apparatus. As long as the patrol area is accessible to the apparatus. it can be deluged as needed to prevent smoldering fires from rekindling, and nearby unburned areas can be saturated with moisture to prevent ignition.
With the great increase in suburban housing development in wildland areas, dual-role firefighting is becoming increasingly common. Fire apparatus designed primarily for one purpose will have to be utilized in other ways.
In this article and in Part 1, we’ve discussed a number of ways in which highcapacity structural firefighting apparatus can be used in wildland firefighting; there undoubtedly are many others. The uniquefirefighting capabilities that make this equipment so useful in structural firefighting also can be used in the wildland setting.
