On Dec. 20, 2012, the EPA Administrator signed a final rule that
determines what Clean Air Act standard applies to units that
combust secondary materials (as opposed to traditional fuels or
virgin ingredients): Identification of Non-Hazardous Secondary
Materials That Are Solid Waste (NHSM Rule). This NHSM Rule is
important because if EPA determines that a fuel is a
waste, then the combustion unit must meet the Final
Emissions Standards for Commercial/Industrial Solid Waste
Incinerators (CISWI Rule) (also signed December 20)—which are
generally more stringent than standards applicable to boilers.
If EPA determines that a fuel is not a waste, then the
combustion unit would be regulated under the applicable MACT
standard, three of which also were revised on December 20: Final
Emission Standards for Area Source Industrial, Commercial, and
Institutional Boilers; Final Emission Standards for Major Source
Industrial, Commercial, and Institutional Boilers and
