Which of the following is a requirement for unpaved haul/access roads?

• A. Maximum opacity of 15%
• B. Silt load of at least 0.5 oz/sqft
• C. Limit vehicle speeds to 15 mph
• D. No dust control plan needed

Answer: (C)

In the context of unpaved haul and access roads, limiting vehicle speeds is crucial for minimizing dust emissions. When vehicles travel at higher speeds, they disturb the surface more vigorously, resulting in increased dust generation. Therefore, establishing a maximum vehicle speed, such as 15 mph, helps control dust and protects air quality by reducing the amount of particulate matter released into the atmosphere.

Implementing speed limits is an effective and practical measure in dust control strategies on unpaved surfaces. It encourages safer driving practices and allows for better management of dust emissions, in line with regulations aimed at reducing air pollution.

The other options do not adequately address effective dust management practices for unpaved roads and would not support air quality standards as significantly as speed limits do. For example, a maximum opacity of 15% relates to visible emissions but doesn’t directly translate to operational measures on unpaved roads. A minimum silt load doesn't focus on controlling dust but rather indicates a standard that might not be relevant for every situation. Similarly, the absence of a dust control plan would disregard necessary preventive measures that are essential for reducing dust from haul roads.