In general, it was decided to classify all screening operations as either dry process material, wet process material, dry fines material, wet fines material, or zero emission material. 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. The factors are not affected by screen size or number of decks.
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 screening 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. Unfortunately, no alternative method to using average values currently exists. These values cannot be modified by adjusting release point information.