March 13, 2013

EPA Clarifies Biogas Status and Stance on Contained Gases

The nonhazardous secondary materials (NHSMs) rule, codified in Part 241, clarifies when nonhazardous materials used as fuels or ingredients in combustion units are solid waste under RCRA. Within this part, EPA defines “traditional fuels” (which are not solid wastes when combusted) to include historically used commercial fuels, as well as alternative fuels such as on-spec used oil.

EPA was recently asked if a facility’s biogas was a traditional fuel. Biogas, which primarily consists of methane and carbon dioxide, is a by-product from the anaerobic digestion of wastewater treatment sludge. With a heating value of approximately 600 Btu per cubic foot, biogas is routinely collected and burned as fuel for heating or power generation.

The agency determined the facility was not generating a traditional fuel; rather, the biogas is a commodity fuel resulting from the processing of a solid waste (e.g., the wastewater treatment sludge). [RO 14830] Although EPA never said in RO 14830 that the biogas could be managed as a nonwaste when combusted per §241.3(b), the agency did say that if it qualifies for the Gas 1 (natural gas and refinery gas) subcategory, it would be subject to the work practice standards under the boiler MACT. Reading between the lines, since only materials that are not solid waste under RCRA can be managed under the boiler MACT rules, the biogas commodity fuel can be managed as a nonwaste if it meets the legitimacy criteria of §241.3(d)(1).

In RO 14830, the agency also took the opportunity to reaffirm its interpretation as to what constitutes a “contained gaseous material” for defining a solid waste. EPA’s longstanding position has been, and continues to be, that gases and vapors flowing through pipes and ductwork are not considered solid waste subject to RCRA, because a pipe or duct is not a container. Conversely, gases and vapors in a container are considered “contained gaseous material” and would meet the definition of solid waste if sent for disposal. To support this interpretation, the agency recently added a definition of “contained gaseous material” to §60.2265 of the CAA incinerator regs. “Contained gaseous material means gases that are in a container when that container is combusted.” [78 FR 9188]


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