Is Your Combustion Unit A Boiler Or An Incinerator? - EPA Finalizes NHSM Rule

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 Process Heaters; and the National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants.

Since 2000, EPA has been attempting (unsuccessfully) to distinguish between wastes and non-waste fuels to place combustion units in the appropriate regulatory category. In the 2000 CISWI Rule and the 2005 CISWI Definitions Rule, EPA said that units that combust waste for energy recovery are not CISWI units. EPA used this determination to identify the best-performing incinerators when developing the 2000 CISWI Rule and the best performing boilers when developing the 2004 Boiler MACT Rule. In 2007, the D.C. Circuit rejected that interpretation and vacated both the 2005 CISWI Definitions Rule and the 2004 Boiler MACT Rule. Natural Resources Defense Council v. EPA, 489 F. 3d 1250, 1257–61 (D.C. Cir. 2007). In 2011, the D.C. Circuit also vacated part of the Portland Cement MACT, because EPA had placed some cement kilns in the wrong regulatory category. Portland Cement Ass'n v. EPA, 665 F.3d 177, 184-85 (D.C. Cir. 2011).

EPA tried to resolve this issue with the first NHSM Rule, promulgated in March 2011. "Identification of Non-Hazardous Secondary Materials That Are Solid Waste," 76 Fed. Reg. 15456 (Mar. 21, 2011). However, EPA again failed to establish clear and legally defensible criteria for distinguishing between wastes and non-wastes, and agreed to reopen this rule. EPA proposed changes to the NHSM Rule in...