NYC-WTC_000229683

NYC 9/11 Public Portal Document

’Dust Control Evaluation Summary 1 October 11. 2001

“scalped” to remove large items such as planters and structural steel/red iron. The red iron is loaded for transport to a specialized cutting operation for cutting and recycling.

The debris is then moved to one of four existing “shakers” located at the site. Large debris, such as metal frames, is segregated from the smaller debris. The larger debris is lifted with a front-end loader and scattered on the ground for subsequent inspection by law enforcement personnel, who use rakes and shovels to manually sort through and inspect the debris. The smaller debris is forwarded to a sifter, which separates the debris into three separate conveyors for inspection by law enforcement personnel. Once the debris is inspected, it is scooped up with a front end loader, loaded onto trucks, and forwarded to the “active bank” for final landfill disposal.

4.0 CURRENT DUST CONTROL PRACTICES

Dust control is currently being addressed on the roads using water. Water trucks are continuously utilized to minimize the potential of dust emissions on the unpaved roads. Additionally, paved roads are periodically misted to limit the potential for dust emissions. Although effective, the effects are short lasting, as evaporation removes the water in a matter of hours, especially on windy days (which is most of the time). Additionally, water will become a problem when the ambient temperature remains below freezing for extended periods of time.

5.0 DISCUSSION OF ALTERNATIVES

A number of alternatives technologies may be used for dust suppression on and around roadways and work areas. Including the following: Water and/or chemical dust suppressants may be applied to roadways, stock piles and sorting fields; geotextiles may be placed on unpaved roadways; unpaved roads may be paved and speed limits may be lowered; artificial or natural wind breaks or wind screens may be constructed as enclosures for specific dust sources; and. ventilation/filtration and misting may be used to capture and remove dust in areas under cover. Based on a preliminary evaluation of these various technologies with respect to operations at the landfill, the application of chemical dust suppressants appears to be the most cost effective.

The use of chemical dust suppressants can reduce the use of water, and thereby reduce the generation of surface water runoff and leachate. In addition, many chemical dust suppressants aid in road stabilization and erosion control, and provide residual dust control thereby reducing the frequency of application. The efficiency of chemical dust suppressants varies, depending on the same factors as water application, including activity levels, climate, initial surface conditions, and spray nozzle parameters. The efficiency of chemical dust suppressants generally falls between 60 and 90 percent reduction in fugitive dust emissions. The degree of control achieved is a function of the application intensity and frequency, and the dilution ratio.

A number of different types of chemical dust suppressants are commercially available for use on most types of emission sources. The different types of dust suppressants include the following:

• Salts, such as calcium chloride and magnesium chloride. • Bitumens, tars and resins, such as fuel oil.

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NYC-WTC_000229684