Compliance Corner.

Fossil Fuel Combustion Wastes Exclusion

Section 261.4(b)(4) of the federal RCRA regulations excludes fly ash waste, bottom ash waste, slag waste, and flue gas emission control waste from the definition of hazardous waste. These wastes are some of the so-called “Bevill wastes,” temporarily excluded from hazardous waste regulation under the October 1980 Bevill amendment [Section 3001(b)(3)(A)] to the RCRA statute (named after the representative who introduced the amendment in Congress). The three classes of excluded Bevill wastes are:

1. Fly ash, bottom ash, slag, and flue gas emission control waste from the combustion of fossil fuels [§261.4(b)(4)];
2. Wastes from the extraction, beneficiation, and processing of ores and minerals [§261.4(b)(7)]; and
3. Cement kiln dust [§261.4(b)(8)].

The discussion below covers the first Bevill waste.

Four large-volume fossil fuel combustion wastes

Fly ash, bottom ash, slag, and flue gas emission control waste generated primarily from the combustion of coal or other fossil fuels are what EPA calls the four large-volume fossil fuel combustion (FFC) wastes. These Bevill wastes are excluded from hazardous waste regulation per §261.4(b)(4). Figure 1 illustrates the scope of this Bevill exclusion for these four wastes at a coal-fired power plant.

Although these wastes were excluded from the definition of hazardous waste in the original May 19, 1980 RCRA regulations [45 FR 33120], Congress required EPA to evaluate whether the temporary Bevill exclusion included in the 1980 regs should continue. After extensively evaluating these waste streams, the agency issued its Report to Congress in February 1988. [EPA/530/SW-88/002, available at https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=500020KW.TXT]

Several years after issuing its Report to Congress, the agency published a final regulatory determination for these wastes on August 9, 1993. [58 FR 42466] In that determination, EPA concluded hazardous waste regulation is inappropriate for these four large-volume FFC wastes. This determination was based on two qualifying criteria; these four wastes are excluded only if they are: 1) generated at coal-fired electric utilities or independent power producers, and 2) managed separately from other FFC wastes. These criteria are incorporated into Figure 2, which is a logic diagram for determining the regulatory status of FFC wastes.

EPA noted that smelter slag is not the same thing as boiler slag (molten bottom ash) and so would not be covered under the §261.4(b)(4) exclusion. Instead, smelter slag might be addressed in the mining and mineral processing waste exclusion at §261.4(b)(7). [RO 12259]

It is fairly clear from guidance [58 FR 42466, RO 11226, 12240] that wastes from a flue gas desulfurization (FGD) system are included in the term “flue gas emission control waste.” What’s less clear is whether spent catalyst and other wastes from a selective catalytic reduction (SCR) system used to control nitrogen oxide (NO_x) emissions is included in that term. In limited guidance, EPA determined spent SCR catalysts enjoy the §261.4(b)(4) Bevill exclusion. [Performance of Selective Catalytic Reduction on Coal-Fired Steam Generating Units, Final Report, June 25, 1997, available at https://www.epa.gov/sites/default/files/2018-09/documents/performance_of_selective_catalytic_reduction_on_coal-fired_steam_generating_units.pdf]

Other, low-volume fossil fuel combustion wastes

In addition to the large-volume FFC wastes, facilities burning fossil fuels generate other wastes, in smaller quantities, from processes related to fuel combustion. Many of these low-volume FFC wastes are co-managed/co-disposed with the four large-volume FFC wastes, and so “their composition and character are ‘masked’ by the combustion [sic] and character of the combustion wastes; that is, they do not significantly alter the hazardous character, if any, of the combustion wastes.” [RO 12021] Thus, EPA believes Congress intended that these low-volume wastes should also be excluded as Bevill wastes under §261.4(b)(4) when they are mixed and co-managed with the four large-volume FFC wastes.

In a 1981 guidance letter [RO 12021], signed by Gary Dietrich of the Office of Solid Waste (hereinafter called the “Dietrich letter”), EPA noted this extension of the Bevill exclusion was limited to low-volume wastes generated in conjunction with the combustion of fossil fuels and that are mixed and co-managed with the four large-volume FFC wastes. Until the agency could complete a more thorough evaluation of the hazardous properties of these other, low-volume wastes or their mixtures with the large-volume wastes, the Dietrich letter stated the Bevill exclusion was extended to include, but not be limited to, the following wastes:

• Boiler cleaning solutions,
• Boiler blowdown,
• Demineralizer regenerant,
• Pyrites (coal mill rejects), and
• Cooling tower blowdown.

However, the Dietrich letter specifically said the following wastes are not excluded under §261.4(b)(4):

• Pesticide or herbicide wastes,
• Spent solvents,
• Waste oils,
• Other wastes that might be generated in construction or maintenance activities typically carried out at utility and industrial plants,
• Any hazardous waste listed in §261.31 or 261.32, and
• Any commercial chemicals listed in §261.33 that are discarded or intended to be discarded.

Years after the Dietrich letter was issued, EPA completed its evaluation of these other, low-volume FFC wastes and issued a March 1999 Report to Congress. In a subsequent regulatory determination [65 FR 32214], the agency distinguished between low-volume FFC wastes that were “uniquely associated” with fossil fuel combustion and those that weren’t. EPA defined “uniquely associated” to mean a waste that “during the course of generation or normal handling at the facility, comes into contact with either fossil fuel (e.g., coal, oil) or fossil fuel combustion waste (e.g., coal ash or oil ash) and it takes on at least some of the characteristics of the fuel or combustion waste.” [65 FR 32219] Furthermore, in the May 22, 2000 regulatory determination, EPA proposed a list of wastes it thought were uniquely associated with the combustion of coal to generate electricity. The list proposed in 2000 did not include all of the wastes that EPA said were covered by the exclusion in the 1981 Dietrich letter.

This inconsistency was resolved in the final FFC rule issued on April 17, 2015. In that rule, EPA codified in §261.4(b)(4) a list of wastes generated from processes that support the combustion of coal or other fossil fuels that, when co-disposed with FFC wastes, are not subject to hazardous waste regulations. These wastes are also referred to as “uniquely associated wastes.” The uniquely associated wastes are:

• Coal pile run-off,
• Boiler cleaning solutions (both fire-side and water-side),
• Boiler blowdown,
• Process water treatment and demineralizer regeneration wastes,
• Cooling tower blowdown,
• Air heater and electrostatic precipitator washes,
• Effluents from floor and yard drains and sumps, and
• Wastewater treatment sludges.

In codifying the above list of uniquely associated wastes, the agency essentially reverted to its position expressed in the 1981 Dietrich letter (RO 12021). These uniquely associated wastes are subject to the hazardous waste regulations when they are not co-disposed with the high-volume FFC wastes. Based on the foregoing discussion, Table 1 summarizes the low-volume FFC wastes that EPA determined are uniquely associated with fossil fuel combustion versus those that aren’t.

Low-volume wastes not uniquely associated with fossil fuel combustion get no breaks whatsoever. If one of these wastes is managed separately, it is subject to regulation as hazardous waste if it exhibits a characteristic or is listed. If a nonexcluded waste is mixed and co-managed with one of the Bevill-excluded large-volume FFC wastes, the Bevill exclusion may be lost, depending on application of the Bevill mixture rule. [65 FR 32220]