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EPA’s Prior Determinations That Landfill Gas is Not a Solid Waste

• Since 1986, EPA has determined under RCRA that landfill gas would be regulated as an 

“air pollutant”, rather than as “solid waste” In that regard, the regulation of MSW 

landfill emissions was considered during deliberations under a RCRA subtitle D 

rulemaking. In 1986 and 1987 the Administrator decided to regulate these emissions 

under the authority of the Clean Air Act. See, e.g. March 6, 1986 Memorandum from 

Marcia Williams to H. Lanier Hickman, Jr. (attached), cited in Definition of Solid Waste 

Compendium, Volume U, (Un)-Contained Gases (December 2010)(attached) (see 

particularly page 9, which refers to the Hickman memorandum and which characterizes

landfill gas as “uncontained” and therefore not “solid waste”). After further 

consideration, the EPA announced in the Federal Register on August 30, 1988 (53 Fed. 

Reg. 33,314) (attached) their decision to regulate MSW landfill emissions under section 

111 of the CAA. This ultimately occurred through the promulgation of the landfill 

NSPS, 40 CFR Part 60, Subparts WWW and Cc in 1996. 

• In the proposed Landfill NSPS standards published on May 30, 1991 (56 Fed. Reg.

24,468) (attached), EPA again reiterated its decision to treat landfill gas as a Clean Air 

Act pollutant (rather than as solid waste).

• The issue was re-raised during public comment for the proposed NSPS. In response, 

EPA specifically stated in response: “the RCRA subtitle D establishes a framework for 

controlling the management of nonhazardous solid waste. Because the intent of this rule 

is to regulate emissions of landfill gas, and not solid waste, this regulation has been 

developed under the CAA instead of under RCRA. Some requirements in the RCRA 

subtitle D regulation are referenced within the NSPS and EG and are necessary to achieve 

compliance with these regulations.” See Air Emissions From Municipal Solid Waste 

Landfills – Background Information for Final Standards and Guidelines, EPA-453/R-94-

021 (December 1995), at pages 1-4, 2-31 to 2-34 (attached). Thus, the concept of 

utilizing RCRA authority and regulating landfill gas as solid waste was specifically 

rejected by EPA at that time. “Although one commenter suggested that LFG emissions 

should be regulated under RCRA authority, the EPA continues to consider Section 111 

NSPS and EG to be the appropriate statutory approach for regulating these emissions 

because the adverse health and welfare effects of concern result from air emissions. 

Therefore, the final notice added MSW landfills as a source category for regulation under 

Section111(b)(1)(A) of the CAA to the priority list in 40 CFR 60.16.” See id.

• On January 16, 2003, EPA issued National Emission Standards for Hazardous Air 

Pollutants: Municipal Solid Waste Landfills (68 Fed. Reg. 2,227), which ensured that 

landfill gas collection and treatment and/or control systems (including combustion units 

and landfill gas used on or offsite in beneficial use projects) achieved MACT level 

controls.

• EPA again noted on March 22, 2004, in revisions to its Criteria for Municipal Solid 

Waste Landfills, Final Rule for Research, Development and Demonstration Permits for 

Municipal Solid Waste Landfills: 
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“With the exception of explosive gas control requirements, landfill gas controls are not 

regulated pursuant to Subtitle D of RCRA: rather landfill gas emissions are regulated 

under the Clean Air Act (CAA). The air criteria in 40 CFR 258.24 refer to CAA 

requirements by requiring compliance with the applicable State Implementation Plan 

provisions under section 110 of the CAA. Specific requirements pertaining to landfill gas 

emissions from MSWLF units are addressed in 40 CFR Part 60,Subparts Cc and WWW. 

Recently, EPA promulgated National Emission Standards for Hazardous Air Pollutants: 

Municipal Solid Waste Landfills (68 FR 2227, Jan. 16, 2003). This rule includes 

requirements for initiating landfill gas collection and control in bioreactor landfills. See 

40 CFR Part 63, Subpart AAAA.... [C]onsistent with section 1006(b) of RCRA, EPA 

sees no need for additional requirements under RCRA to address air emissions in today’s

rule.” 

See Final Rule, Research, Development and Demonstration Permits for Municipal Solid 

Waste Landfills, 69 Fed. Reg. 13,242 (2004) (attached).

• Thus, by 2004, all landfills regulated under WWW were regulated under the Section 112 

Landfill MACT standards promulgated at 40 CFR Part 63, Subpart AAAA. In all 

instances, the notion was that landfill gas would be combusted either in open flares, 

enclosed combustors (enclosed flares, turbines, engines or boilers), or the gas would be 

treated (compressed, filtered to 10 microns or less, and cooled or chilled) and routed for 

use as fuel as either onsite or offsite. When combusted in turbines, engines or boilers, the 

landfill gas is either controlled to NSPS-specified treatment limits, or it is ”treated” as per 

the NSPS for end use. 

• Having exercised its asserted authority under RCRA Section 4004 to regulate air 

emissions from landfills as a “designated air pollutant” under the Clean Air Act rather 

than as solid waste under RCRA, the combustion of this designated air pollutant in a 

flare, turbine, boiler or engine should not be deemed to be the combustion of a solid 

waste. Stated differently, something cannot be a designated air pollutant and a solid 

waste at the same time. 

• For purposes of Section 129, the term “solid waste’ has the meaning established by the 

Administrator pursuant to the Solid Waste Disposal Act. The meaning established for 

many years by the Administrator pursuant to the Solid Waste Disposal Act (RCRA) was 

that landfill gas would not be treated as solid waste, and its combustion would not be 

treated as solid waste combustion, but rather, as an uncontained gaseous emission 

regulated as a designated air pollutant by the Clean Air Act. There is nothing in the NonHazardous Secondary Materials Rule (NHSM) that establishes that landfill gas is a solid 

waste, and the regulatory impact analysis for the CISWI rule gave no consideration of 

landfill gas as a source type for establishment of MACT. Indeed, the NHSM establishes 

that solid waste follows the meaning of solid waste for purposes of Subtitle D, 40 CFR 

258.2. That definition excludes uncontained gas from the definition of solid waste, and 

has via rulemaking always excluded landfill gas.
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Longstanding EPA Precedent that Uncontained Gas is not a Solid Waste

• The statutory definition of “solid waste” includes “contained gaseous material.” 42 USC 

§ 6903(27). 

 

• EPA interpretation of the term “contained gaseous material” demonstrates that RCRA 

only applies to “contained” gases, to the exclusion of “uncontained” gases. 

• EPA’s interpretation of “contained” has been limited to gas present inside “containers.”

o In a 1989 preamble to a final rule dealing with the listing of certain hazardous 

substances under RCRA, EPA stated that EPA “believes our authority to identify 

or list a waste as hazardous under RCRA is limited to containerized or condensed 

gases (i.e., section 1004(27) of RCRA excludes all other gases from the definition 

of solid wastes and thus cannot be considered hazardous wastes). See Hazardous 

Waste Management System: Identification and Listing of Hazardous Waste, 54 

Fed. Reg. 50968, 50973 (Dec. 11, 1989).

o The CISWI Rule promulgated in 2000 defined contained gaseous material as 

limited to “gases that are in a container when that container is combusted.” (EPA 

provided no explanation for deletion of this definition, which was not mandated 

or even discussed in the D.C. Circuit’s NRDC decision.)

o Similarly, 40 CFR Part 60, Subpart EEEE, governing Other Solid Waste 

Incineration Units, includes the same definition of “contained gaseous material.”

• EPA has a longstanding policy providing that fume incinerators are subject to regulation 

only under the CAA, and not also RCRA.

o For example, in the preamble to a 1982 dealing with regulation of incinerators 

that burn hazardous waste, EPA stated that “fume incinerators are subject only to 

regulation under the Clean Air Act . . . . Fume incinerators which are used to 

destroy gaseous emissions from various industrial processes, for example, are not 

subject to regulation under RCRA. In general, the RCRA standards do not apply 

to fume incinerators since the input is not identifiable as a solid waste.” See The 

Hazardous Waste Management System, Interim Final Amendments to Interim 

Final and Final Rules, 47 Fed. Reg. 27,520, 27,530 (June 24, 1982). See also, 

RCRA Superfund Hotline Monthly Summary, 9488.1986(03) available at RCRA 

Online. 

o EPA has reaffirmed this position on subsequent occasions. For example, in the 

1989 preamble discussed above, EPA stated that “fume incinerators are installed 

as air pollution control devices pursuant to regulations under the Clean Air Act; 

they are used to destroy gaseous emissions from various industrial processes. 

EPA concluded that, in general, RCRA standards do not apply to fume 

incinerators because the input (an uncontainerized gas) is not a solid waste.” 54 
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Fed. Reg. 50,973 n.5. See also, Memorandum from Matthew Straus, Chief, 

Waste Characterization Branch, to Clifford Ng, Engineer, EPA Region II, dated 

June 17, 1987, available at RCRA Online (“Methanol-laden air from the drying 

and granulation step of the process does not meet the definition of solid waste 

under RCRA because it is in vapor form and not confined in a container.”)

• On a few occasions, some in EPA attempted to take a broader view of contained gas (e.g. 

piping was enough) but that view was rejected by the courts or the administrative 

tribunal. See, e.g. In re BP Chemicals America, Inc., RCRA Appeal No. 89-4, 1991 EPA 

App. LEXIS 27; 3 E.A.D. 667 (EPA Admin., Aug. 20, 1991) (The Administrator 

specifically rejected Region V's argument that gaseous emissions were "contained" by the 

process units they passed through, associated piping or the facility itself, holding that the 

Agency's definition of the term "contained" has consistently been confined "in the 

narrower sense of being in an individual container such that the gas is amenable to 

shipment”). See also In re: Chemical Waste Management of Indiana, Inc., RCRA Appeal 

No. 95-4, 1995 EPA App. LEXIS 31(EPA Environmental Appeals Board, Aug. 23, 1995)

(emissions from microencapsulation of hazardous debris) (The EAB concludes the air 

emissions are excludable from Subtitle C regulation "because the air emissions that the 

Region seeks to regulate are not containerized.”)

• In the landfill gas context, that view was similarly rejected by stakeholder groups 

assigned to review combustion issues. See, e.g., Recommendation from the Incinerator 

Workgroup on Section 112 Subcategories April 28, 1998 (“Section 129 Requirements. 

Section 129 applies to "solid waste combustion.” Because solid waste is defined to 

exclude gases (except gases which are in containers), Section 129 does not apply to 

landfill gas flares.”) (available at http://www.epa.gov/ttn/atw/iccr/incin/rec-112.pdf).

 The final Boiler MACT rule expressly recognizes that landfill gas constitutes a “gaseous 

fuel.” (76 Fed. Reg. 15,684)

 See also: 

o Burning of Hazardous Waste in Boilers and Industrial Furnaces, Final Rule, 56 

Fed. Reg. 7134, 7200 (Feb. 21, 1991) (activated carbon units used as air emission 

control devises are not subject to RCRA because “the gas originally treated is not 

a solid waste (it is an uncontained gas).” See also RCRA Online Determinations 

12783 (November 20, 1986) (Volatile organics released to the air are not 

hazardous waste because they are not solid wastes. (They do not fit the definition 

established in §1004(27) of RCRA as "contained gaseous materials.")”

o Hazardous Waste TSDF - Technical Guidance RCRA Air Emission Standards for 

Process Vents and Equipment Leaks, EPA-450/3-89-021 (July 1990) at pages 2-3: 

"Air standards have been promulgated for the control of air emissions from 

permitted hazardous waste incinerators. 40 CFR Part 264, Subpart O. These 

standards require that incinerators burning hazardous waste be operated to achieve 

a destruction and removal efficiency (DRE) of at least 99.99 percent for those 
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primary organic hazardous constituents listed in the facility permit However, the 

process vent stream (i.e. gases and vapors) from a hazardous waste management 

unit would not be classified as a hazardous wastes. Noncontainerized gases 

emitted from hazardous wastes are not themselves hazardous wastes because the 

RCRA statute implicitly excludes them. Therefore combustion of process vent 

streams in an incinerator is not subject to the 99.99 DRE requirement." 

o Hazardous Waste Treatment, Storage, and Disposal Facilities (TSDF): 

Background Information for Promulgated Organic Air Organic Air Emission 

Standards for Tanks, Surface Impoundments, and Containers, EPA/453/R94/076b (November 1994) (since organic vapors emitted from hazardous waste 

are not solid or hazardous waste, control devices installed to comply with Subpart 

CC organic vapor control requirements are not hazardous waste management 

units and do not require RCRA permits).