In the aftermath of a major wildfire, rehabilitation of the burned area is often necessary. This may be as simple as a ground crew planting trees, spreading of mulched hay by ground rig or helicopter, reseeding the area by ground or air or in extreme cases, the application of hydromulch. These efforts are usually undertaken to prevent erosion, which may result in mudslides and damage to property or runoff which could possibly contaminate water supplies. In the future, these rehabilitation projects will become more numerous. The Bush Administration’s budget for the Healthy Forest Initiative has earmarked a substantial increase in funding for these types of projects.
Following the devastating California wildfires of last October, Aero Tech of Clovis, New Mexico was contracted by the Bureau of Indian Affairs to apply hydromulch to specific, areas subject to erosion, as well as sensitive areas in the San Bernadino vicinity. Hydromulch is a combination of mulched paper and hay or other vegetative material which may or may not contain grass seed. When applied, it binds the soil and provides for rapid germination of grasses and other species, slowing erosion.
When properly mixed with water, the hydromulch becomes a slurry mix that can best be described as the consistency of slime. It is pretty nasty stuff. It sticks to everything and the residue must be removed from the equipment after every couple of loads. If the mixture contains too much water, time and money are wasted because of the extra weight that has to be carried. If the mixture does not contain enough water, the material can be very difficult to flow out of the aircraft. A good water supply is very important to the efficiency of the project, as a tremendous amount of water is applied to a relatively small area in a short amount of time. Occasionally, a well has to be drilled specifically for a particular hydromulch contract. The mixture is dyed a deep green for a visual indication of where the material has been applied. Oftentimes, especially when helicopters are used to apply the hydromulch, the dye aids the aircrew in making a uniform application of the material. They simply fill in the blanks.
The hydromulch product Aero Tech used was Soil Set. It was applied at the rate of 800 pounds per acre. Soil Set is designed to stabilize the soil and stop erosion. It requires a mulch mixture of 500 pounds of wood and paper mulch per acre with a total volume of 2,400 gallons per acre. This equates to about one-fourth of an acre per load, requiring multiple take-offs and landings and a well-coordinated ground crew to expedite the loading process.
The AT-802s applied 87,500 gallons of hydromulch in a ten-hour period. This surprised observers on the ground. One of the United States Forest Service tanker base managers made the comment that it would have been very difficult to apply that many gallons during that time frame with two heavies.
Ted Stallings, owner of Aero Tech, said their customer was extremely pleased with the expertise of the crew and the overall uniform coverage of the hydromulch. The application was in a very steep (60° slopes) and sensitive area. Aero Tech aircraft were able to apply the product right up to buildings without receiving any complaints. As can be seen in the pictures, there is a water treatment facility in the background that required pilot vigilance to avoid flying over.
In Aero Tech’s situation, the areas to be treated were placed onto shape files and downloaded into their GPS guidance systems. This made the applications very precise and consistent. The use of GPS guidance systems with hydromulch applications creates a challenge for the pilot. The parallel tracks are only seven to ten feet apart, henceforth, the pilot must maintain great vigilance to insure the drops do not overlap or cross each other.
After the application, the results are downloaded from the aircraft and a printout is viewed to validate the quality of the work. This is presented to the customer for his assurance that the mulch was properly applied. Shape files, or polygons, as they are sometimes called, are also very useful for planning purposes. The pilot displays the files on his screen in his cockpit, illustrating the exact bearing and distance to the location.
Aero Tech used two of its Air Tractor AT-802 aircraft for the hydromulch contract. These aircraft fight fires as air tankers during the fire season and reseeding or applying hydromulch after the fire season. The AT-802 is the largest single-engine aircraft in the world and is capable of carrying 800 gallons of material. It can operate off small, unimproved airstrips and has enough horsepower to maneuver at high altitudes while fully loaded. The two AT-802s used on this contract were identical, except for their hydraulic dispersal gates. One had the more conventional Transland hydraulic gate, while the other had an Air Tractor-manufactured fire gate with doors that open in a clamshell fashion. Both dispersal gates did an excellent job.
Aero Tech flew the aerial hydromulch from the USFS San Bernadino tanker base. The tanker base personnel were a great assistance and good to work with. They were impressed with the Aero Tech operation. It is historically significant that this was the first time that SEAT aircraft had operated on contracts in the state of California.
When it comes to hydromulch contracts, Aero Tech can provide a turn-key operation. Besides doing the application, they also supply the hydromulch along with the crews to mix and load. By having an experienced crew that works together, they know what to expect, improving the efficiency of the operation. Stallings and his team are one of the more experienced fixed-wing operations in hydromulch applications. They have conducted mulching operations in numerous western states. Now that summer is approaching, Ted Stallings and Aero Tech will change hats and go back into the firefighting mode until next fall when possibly there will be another hydromulch job.