Tactic CR-10: Burning Contaminated Vegetation
Burning is used primarily to volatilize and oxidize residual contaminants from vegetation after other tactics have been used to recover most of the spilled substance. This tactic is especially useful for light coatings on leaves of sedges and grasses that are elevated above the tundra surface (Figs. 52–53). Burning was first tested on the North Slope in the late 1970’s (Fig. 54). This tactic is not appropriate for removing pooled product from the ground surface. The relatively large amount of heat required to burn pooled product could 1) cause vertical migration of the substance into the rooting zone and 2) induce thermokarst in the underlying tundra soil.
Typically, one worker uses a metal rake to orient oiled leaves and stems more or less vertically. A second worker uses a weed burner, which consists of a flame nozzle, hosing, and a propane tank. The flame nozzle is held just above the contaminated vegetation until the vegetation is burned down to stubble. Burn residue can be recovered with hand tools, but the benefit of recovery should be carefully weighed against the potential for causing additional physical damage to the tundra.
The risk of damage from burning is relatively modest in moist and wet tundra dominated by sedges. Much of the biomass of these plants, including the buds from which new leaves sprout, is deep enough to be protected from the heat of the fire. Use additional caution in drier tundra where shrubs, mosses and lichens are abundant, as these growth forms have little or no ability to sprout from belowground parts.
Considerations and Limitations
- Burning vegetation contaminated with weathered oil or fuel may produce a residue that is difficult to clean up.
- Burning as soon as possible after a spill will increase the likelihood of complete combustion because fewer of the volatile components (e.g., benzene) in the spilled substance will have evaporated.
- Follow proper safety procedures and use personal protective equipment, as required.
- Burning should be considered only when there is minimal risk that the fire will spread to unaffected areas. This consideration is especially important when dry sedge and grass leaves (i.e., dead plant litter) are present.
- Permission must be obtained from the Alaska Department of Environmental Conservation and potentially from the U.S. Environmental Protection Agency before burning tundra vegetation.
- This tactic has been adapted from Tactics B-2 and SH-10 in the Alaska Clean Seas Technical Manual (http://www.alaskacleanseas.org/techmanual.htm).
Equipment, Materials, and Personnel
- Metal rake (1 worker) – to orient oily vegetation.
- Weed burner with propane tank (1 operator) – to ignite spilled residue and vegetation.
- Fire extinguisher (1 operator) – to suppress unwanted fire.
- Fans (1 operator) – to increase burning efficiency (optional, if conditions are appropriate).