production. One of the facility furnaces is subjectto NSPS Subpart

### UUU (Calciners and Dryers in Mineral Industries). Two other facility furnacespredate the NSPS applicability date.

3.0 Technical Review 

## - Emission Units, Pollutants, and Control Technologies

3.1 Emissions and Controls

Sand and Gravel Mining/Proce~sin~'~~
Emissions from the production of sand and gravel consistprimarily of particulatematter 

### (PM) and particulate matter less than 10micrometers (PM-10) in aerodynamic diameter, which 

### are emitted by many operations at sand and gravel processing plants, such as conveying, screening, crushing, and storingoperations. Generally, these materials are wet or moist when handled, and process emissions can be negligible. 

### A substantialportion ofthese emissions may consist of heavy particles that settle out 

### within the plant. Other potentially significant sources of PM and PM-10 emissions are 

### haul roads. Emissions fiom dryers include PM and PM-10, as well as 

### typical combustion products including CO, C02 

### ,and Nh. 

### In addition, dryersmay be sources of volatile organic compounds (VOC) or 

### sulfur oxides (S@) emissions, depending on the 

### type of fuel 

### used to fire the dryer.

With the exception of drying, emissions from sand and gravel operations primarily are 

### in the form of fugitive dust, and control techniques applicableto fugitive dust sources are appropriate. Some successful control techniques used for haul roads are dust suppressantapplication,paving, route modifications, and soil stabilization; for conveyors, covering and wet suppression; for storage piles, wet suppression, windbreaks, enclosure, and soil stabilizers; for conveyor and batch transferpoints, wet suppression and various methods to reduce fieefall distances (e. g., telescopic chutes, stone ladders, and hinged boom stacker conveyors); and for screening and other size classification, covering and wet suppression. Wet suppressiontechniques include application ofwater, chemicals andforfoam, usually at crusher or conveyor 

### feed andlor discharge points. Such spray systems at transfer points and on material handling operations have been estimated to reduce emissions70 to 95 percent. Spray systems

### can also reduce loading and wind erosion emissions from storagepiles ofvarious materials 80 

### to 90 percent. Control efficienciesdepend upon local climatic conditions, sourceproperties and duration of control effectiveness. Wet suppression

### has a carryover effect downstream of the point of application of water or other wetting agents, as long 

### as the surface moisturecontent is high enoughto cause the finesto adhere to the larger rock particles.

In additionto figitive dust control techniques, some facilitiesuse add-on control devices to ' reduce emissions of PM and PM-10 

### hm sand and gravelprocessing operations. Controls 

### in use include cyclones, wet scrubbers, venturi scrubbers, and fabric filters. These types of controls are rarely used at construction sand and gravel plants, but are more common at industrial sand and gravel processing facilities.

NMMProc TSD 6-14-02 Created on 6/18/2002 9:39:00AM