What dust control requirement applies to inactive sites?

• A. Visible soil cover
• B. Maximum TFV of 75cm/sec
• C. No requirement for vegetation
• D. Soil crust or visible moisture

Answer: (D)

On inactive sites, the requirement for maintaining a soil crust or visible moisture is vital for dust control. A soil crust acts as a physical barrier that reduces the potential for dust particles to become airborne due to wind or other disturbances. It is formed when soil particles bind together, especially after rains or irrigation, creating a hard surface that keeps the dust settled. Visible moisture, on the other hand, helps to keep the particles damp, preventing them from being lifted into the air.

The importance of this requirement lies in its effectiveness in minimizing dust emissions from areas that are not currently active in terms of operations, while also promoting safety and environmental protection. In contrast, other options listed, such as visible soil cover and vegetation, may have specific requirements for active sites, but they are not the primary focus for control on inactive sites. Hence, maintaining a soil crust or ensuring the presence of moisture is the correct emphasis for dust control in such scenarios.