CBM Smoke Management & Post-Burn Evaluation 3 — Questions and Answers
Question 1: Under 40 CFR Part 51 Regional Haze Rule, prescribed fire managers must consider impacts to:
- State Implementation Plan emission budgets only
- Mandatory Class I Federal Areas such as national parks and wilderness areas (Correct answer)
- Private receptor sites within one mile of the burn unit
- EPA non-attainment zones for SO2
Correct answer: Mandatory Class I Federal Areas such as national parks and wilderness areas
The Regional Haze Rule specifically protects visibility in mandatory Class I Federal Areas, requiring coordination when prescribed fires may impact those airsheds.
Question 2: Which condition is most likely to cause a prescribed fire smoke plume to 'fumigation,' meaning smoke is mixed downward to ground level at a receptor site?
- A convective plume that overshoots the mixing height
- An elevated stable plume intercepted by a growing mixing layer the following morning (Correct answer)
- Transport winds exceeding 20 mph at ridge level
- Complete combustion of fuel with minimal particulate output
Correct answer: An elevated stable plume intercepted by a growing mixing layer the following morning
Morning heating erodes the inversion, and the rising mixing layer reaches an elevated stable plume, flushing it downward to the surface—this is fumigation.
Question 3: In a post-burn evaluation, a burn manager finds that soil in portions of the unit appears ash-white and friable several inches deep. This finding most likely indicates:
- Desirable sterilization of invasive plant seeds
- High severity fire that may have damaged soil structure and biological communities (Correct answer)
- Normal smoldering combustion of surface litter
- Complete consumption of fine fuels without soil impact
Correct answer: High severity fire that may have damaged soil structure and biological communities
White ash several inches into the soil profile indicates high temperatures that can damage soil aggregates, mycorrhizal networks, and organic matter.
Question 4: The Haines Index (LI) specifically addresses which atmospheric smoke management concern?
- Smoke dispersion capacity of the boundary layer
- Potential for large or erratic fire behavior due to dry, unstable lower atmosphere (Correct answer)
- Rate of PM2.5 deposition near smoke receptors
- Wind speed at smoke transport level
Correct answer: Potential for large or erratic fire behavior due to dry, unstable lower atmosphere
The Haines Index measures atmospheric stability and moisture in the lower troposphere to indicate potential for erratic plume behavior and large fire development.
Question 5: When a smoke management plan requires a minimum transport wind speed of 8 mph, the primary reason is to:
- Prevent spotting beyond the burn unit perimeter
- Ensure adequate horizontal movement of smoke away from receptors (Correct answer)
- Maintain flame lengths within prescription parameters
- Reduce the Ventilation Index to acceptable levels
Correct answer: Ensure adequate horizontal movement of smoke away from receptors
A minimum transport wind speed ensures smoke is physically moved away from sensitive receptor areas rather than stagnating.
Question 6: Which post-burn documentation practice is most important for supporting future prescribed fire program planning and regulatory compliance?
- Photographing flame lengths during ignition operations
- Recording actual acreage burned, fuel consumption estimates, and smoke observations with weather data (Correct answer)
- Logging the names of all personnel who participated in the burn
- Noting the cost per acre of ignition materials used
Correct answer: Recording actual acreage burned, fuel consumption estimates, and smoke observations with weather data
Acreage, fuel consumption, and correlated weather/smoke observations create the empirical record needed for emission calculations and program improvement.
Question 7: A burn produces heavy black smoke early in the ignition phase. The black coloration most likely indicates combustion of:
- Dry fine fuels with high oxygen supply (flaming phase)
- Incomplete combustion of heavy fuels or plastic debris with oxygen deficiency (Correct answer)
- Green slash with high moisture content in flaming combustion
- Mineral soil organic fraction under high heat
Correct answer: Incomplete combustion of heavy fuels or plastic debris with oxygen deficiency
Black smoke is characteristic of incomplete combustion, often from heavy fuels, high-moisture vegetation, or oxygen-limited conditions producing soot and tar aerosols.
CBM Smoke Management & Post-Burn Evaluation 3
Under 40 CFR Part 51 Regional Haze Rule, prescribed fire managers must consider impacts to: