Project Profile: Aerial Hydromulching Jump-Starts Los Alamos Fire Recovery
One of the largest reseeding projects in the United States helped reclaim public lands decimated by the Los Alamos fire last May. Aerial hydromulching was used to reseed 1,450 ac. of burn area in New Mexico with native grasses. The land is held by the Forest service, the Department of Energy, and the Bureau of Indian Affairs.
The fire burned more than 47,000 ac. altogether, much of it in mountainous terrain. The main objective of the reseeding program was to minimize erosion in the steeper areas of the burn. Areas were prioritized based on burn severity—”where the fire burned the hottest and damaged the soil the worst,” points out Tammy Gallegos of the National Park Service, which administered the hydromulching contract.
“The immediate concern was protection of life and property, so we needed to do whatever we could to protect that,” states Gallegos. “The entire watershed was burnt, and when we get heavy rains in the top of the watershed, there’s just nothing there to stop it from going down. That impacts communities downstream, so it was important for us to try to get the soil stabilized in some way.” Soil scientists and vegetation specialists examined the area and recommended reseeding as the best course for limiting erosion.
Completing the task before New Mexico’s heavy summer rains began was critical. Western States Reclamation Inc. of Broomfield, CO, carried out the project. Four planes cycled simultaneously to cover approximately 50 ac. per day, using Global Positioning System to lock in on the coordinates of the high-priority areas.
The planes dropped a combination of hydromulch slurry, quick-germinating native grass seeds, and urea fertilizer. The slurry solution required continuous mixing in four large mix-and-batch hydromulchers. Western States Reclamation crews worked 14 hours a day onsite at the Los Alamos Airport to keep the planes loaded. The project was completed in late July.
Known as “air tractors,” the specialized fixed-wing aircraft are designed for spraying applications ranging from pesticides and fertilizers to fire suppressants. Western States Reclamation has reseeded high-altitude steep slopes throughout the Western US, including hazardous-waste sites, landfills, and mined lands. Aerial hydromulching is the method of choice in areas where truck-based hydromulchers cannot easily gain access. For areas as extensive as the Los Alamos project, the fixed-wing planes are less expensive to operate than helicopters.
Although the area would eventually have reseeded naturally and recovered from the effects of the fire, the process would have been much slower and the potential for severe erosion much greater. “A number of efforts were already underway prior to our involvement to slow erosion in the steep canyon areas, including felling burnt trees and setting up straw wattles to act as additional breakers,” recalls soil scientist David Chenoweth, president of Western States Reclamation. “But ultimately vegetation is your best erosion control.”
The three species of native grasses used in the reseeding effort are cereal rye, slender wheat grass, and mountain brome. The rye is an annual grass that germinates quickly, providing immediate erosion control. The wheat and brome are perennials that, although slower to germinate, will provide long-lasting coverage.
Migration of contaminated soils—the legacy of decades-old nuclear testing—has been a concern at Los Alamos National Laboratories, which is owned by the Department of Energy. However, Gallegos says contamination was not an issue on these steeply sloped areas, the vast majority of which belong to the Forest Service.
