This policy included a standardized approach to evaluating emissions from mineral industry aggregate crushing operations. In general, it was decided to classify all crushing operations as either primary crushing, dry process material crushing, wet process material crushing, dry fines material crushing, or wet fines material crushing. Standardized PM10 emission factors were assigned to each classification based on the expected annual average particle size distributions and moisture contents. Predetermined fugitive dust control efficiencies were also identified for specific types of devices and techniques. These emission factors are substantially different than those previously used by the District and are not affected by crusher type or size.
Emissions are dependent only on material type and throughput.
These factors are substantially different from those used previously by the District. Trace metal concentrations in aggregate dust released from aggregate crushing operations can vary between sites. The following default trace metal concentrations should be used to estimate compound specific emissions where representative site specific information is unavailable. These values cannot be modified by adjusting the release point information. Material throughputs should represent the entire device.