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Permitting: Dust Control and the Aggregate Industry
Sand and gravel, asphalt production, and concrete processing operations are monitored by the Division of Air Quality to ensure compliance with fugitive dust rules. As the ground dries and construction-related activities peak - around April through the late Fall - the Division fields a number of questions and complaints about dust. Below, you’ll find a basic overview of related issues. The repository includes information on permits and compliance for the sites listed.
Fugitive Dust
Fugitive dust is simply dust that is stirred up, creating an air quality problem. It is made up of fine particles called particulate matter or PM. Because it irritates eyes and nasal tissue and seriously impacts the respiratory system, PM is a health concern. It also inhibits normal plant growth and development.
Fugitive dust may come from gravel operations, construction or demolition activities, land clearing and exposed surfaces, roadways, and mining activities. Along the Wasatch Front and in other areas, Air Quality rules specify that dust created by these activities be minimized. If the operation is along the Wasatch Front, owner/operators are also required to develop and submit a dust control plan. (See a summary of criteria for developing a plan.)
Opacity measurements are one way to determine the effectiveness of a source’s dust control efforts. Measuring with instruments is expensive and requires extensive planning. Measuring opacity with a trained eye is cheaper, requires little advance planning, and can occur more frequently.
Opacity limits are contained in a source’s air quality permit. Enforcement actions can be taken against those with excessive opacity. A compliance inspector patrols areas during daylight hours; the Division also responds to citizen complaints. When a notice of violation is issued for excusive fugitive dust, the source is required to submit a plan detailing additional control measures to reduce the dust problem.
Opacity
Opacity is the amount of light that is blocked by something else – such as smoke or a tinted window. It can provide a qualitative idea of the concentration of particulate matter in the air.
Opacity is measured as a percentage - 0% means that all light passes through; 100% means that no light can pass through. The more particles present, the higher the opacity percentage is.
Opacity is commonly determined through visual observation. Inspectors train and certify as “Visible Emission Observers” and pass tests measuring their ability to determine the opacity of plumes with known percentage levels.
To determine opacity, the observer must be located in a position between the source and the sun, with the sun behind the inspector. The angle between the source, the observer and the sun cannot be less than 110 degrees. Because small particles in the air scatter sunlight, opacity always appears greater when observed facing the sun. Twenty-four observations are recorded at 15-second intervals over a six-minute period. Opacity is the average of these 24 observations.
Procedures similar to Method 9 are followed in determining opacity for mobile and intermittent sources. However, the requirement for observations to be made at 15-second intervals over a six-minute period does not apply.
Control Options
There are a variety of ways to meet the requirements to control emissions - depending on the site, the season, and the moisture content of the soil or aggregate in use. Examples include:
- To prevent tracking dirt onto a paved road adjacent to a site, the source could:
a. Lay down a work surface of 2"- 3" rock.
b. Lay down a work surface of pavement, such as concrete or asphalt.
c. Install a metal cattle guard.
- To prevent dust spilling from haul trucks, one or more of these steps may be needed:
a. Clean off truck and tires before leaving the site.
b. Check and sweep trucks as they exit the site.
- An undercarriage and side water spray could be used to clean trucks and tires before leaving a site. Dust and oils would be filtered from the water before it reaches a drain.
- Dust can be prevented from being blown from a site by a variety of measures; watering, dust suppressants, structural berms, planting vegetation, and assorted site-dependent work practices may be used.
Finally, keep in mind that all loads leaving a site must be covered with a tarp. This is a requirement of the Utah Department of Transportation.
Contacts
If you'd like to report a dust concern, contact a member of our compliance staff online or by calling 801-536-4000. For questions about permit requirements, contact Tim Andrus.
