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In the United States, hazardous wastes are subject to regulations mandated by the Resource Conservation and Recovery Act (RCRA). Every month, we provide clear, in-depth guidance on a different aspect of the RCRA regulations. The information presented here is an excerpt from McCoy’s RCRA Unraveled, 2020 Edition.

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Burning Used Oil

Used oil is burned for energy recovery at numerous facilities throughout the United States. Available information indicates that about 82% of recycled used oil is burned as a fuel, with the balance being re-refined into recycled lube oil or other products. The units burning the greatest amounts of used oil as fuel are asphalt plants, industrial boilers, utility boilers, steel mills, and cement kilns. [Used Oil Re-refining Study, July 2006, available at] Here, we discuss the regulatory aspects of such combustion. Figure 1 shows the Part 279 issues that must be considered when burning used oil.

Figure 1

The used oil specification

In the 1970s and 1980s, numerous facilities were burning used oil for energy recovery, because it was a cheap, high-Btu fuel. However, EPA became concerned about the potential human health effects associated with air emissions from such used oil burning. Some used oil contains fairly high levels of carcinogenic or toxic constituents that could be emitted in stack gas. Schools, hospitals, and apartment buildings that burn contaminated used oil typically use low-efficiency boilers, have little or no air pollution controls associated with them, and are located in residential areas.

In writing the Part 279 provisions dealing with used oil burning, EPA attempted to balance its desire to encourage recycling by energy recovery and its concern over the potential impact of air emissions from used oil combustion. The primary means that the agency formulated to balance these conflicting issues is the used oil fuel specification. EPA established the specification for used oil that will be burned for energy recovery on November 29, 1985. [50 FR 49164] As shown in Table 1, the specification addresses the heavy metal and total halogen content, as well as the flash point, of used oil destined for energy recovery.

Table 1

Arsenic, cadmium, and chromium are known carcinogens, and increased ambient concentrations would cause an increased risk of cancer to exposed individuals. Specification levels for these three metals were set based on metal concentrations found in dirty virgin fuel oils. The specification level for lead, conversely, was set based on meeting the national ambient air quality standard (NAAQS) for lead in densely populated areas. [November 29, 1985; 50 FR 49184–6]

The total halogen specification will minimize hydrogen chloride emissions that can increase ambient levels of hydrochloric acid and contribute to acid rain. [50 FR 49181] The total halogen limit of 4,000 ppm operates independently of the 1,000-ppm rebuttable presumption level for determining if listed spent solvents have been mixed into used oil. In other words, used oil for which the presumption of mixing with hazardous waste has been rebutted may be burned as on-specification used oil if the total halogen content is no greater than 4,000 ppm, or as off-spec used oil if the content is greater than 4,000 ppm. [RO 14340]

Although used oil typically has a flash point of greater than 200°F, a minimum flash point of 100°F is included in the specification because that is the American Society for Testing and Materials (ASTM) specification level for virgin fuel oils. [50 FR 49187]

The presence of PCBs in used oil is not one of the used oil fuel specifications. Thus, used oil can be on-spec, even if it contains between 2 and 50 ppm PCBs. In a footnote to the specification contained in §279.11, however, EPA has noted that used oil containing PCBs that will be burned for energy recovery is subject to §761.20(e). That section of the TSCA regs notes that PCB-contaminated used oil (containing between 2 and 50 ppm PCBs) may only be combusted in certain types of units (TSCA or RCRA incinerators, TSCA high-efficiency boilers, industrial furnaces or boilers as defined in §260.10, or utility boilers); certain notification requirements apply as well. “Although the RCRA regulations do not identify the presence of PCBs in used oil as relevant to the determination of whether the used oil is on- or off-specification, the presence of PCBs in used oil is relevant for determining the applicability of the TSCA regulations for the burning of used oil.” [RO 14606] Note that burning used oil that contains >50 ppm PCBs for energy recovery is prohibited. [§761.20(a), RO 14117]

The existence of the used oil specification does not require generators to analyze their used oil to determine if it meets the spec before the oil is transported offsite to a processor or fuel blender—that’s the receiving facility’s job. [EPA/530/H-98/001] A generator would only have to determine compliance with the used oil specification if it was burning used oil onsite or was sending used oil directly to a burner; in either of these situations, the generator would also be a used oil marketer. We find that some generators (especially at utility power plants) do analyze their used oil on a routine basis; however, such practice is typically required because of TSCA concerns or as a business arrangement with the used oil collector.

In another footnote to the used oil specification, EPA notes that the specification is not applicable for used oil that is mixed or contaminated with hazardous waste. [RO 14110, 14606] With the exception of noncharacteristic mixtures of characteristic waste and used oil (and noncharacteristic mixtures of ICR-only listed waste and used oil), mixtures of hazardous waste and used oil are regulated under the BIF regs in Part 266, Subpart H when burned for energy recovery.

Burning on-specification used oil

Once it’s established that used oil meets the fuel specification, the scope of regulations that apply to the oil diminishes dramatically. Provided the entity who asserts that the used oil is on-spec meets the following three qualifying conditions, neither Part 279 nor any other RCRA requirement applies to that material [§279.11, RO 14606]:

  • Documents the finding that the used oil meets the specification via testing or other methods and retains records of these documents for three years [§279.72],
  • Has an EPA ID number [§279.73], and
  • Maintains records of any shipments of the on-spec oil to used oil burners [§279.74(b)].

Once these conditions are met, the on-spec used oil is not subject to RCRA regulation and may be managed the same as any conventional fuel, such as virgin fuel oil. [November 29, 1985; 50 FR 49189, RO 14755] On-spec used oil may be burned in any type of combustion unit, including those in schools, hospitals, apartment complexes, etc. In fact, the agency will even allow on-spec used oil to be used in the manufacture of products such as ammonium nitrate fuel oil blasting agents. [RO 11807]

Bilge water collected from ships contains small amounts of used oil. Once the used oil is separated from the water (using filtration, centrifugation, and demulsification), the recovered used oil is burned for energy recovery. However, because the bilge water meets the used oil spec and the generator complies with §§279.72, 279.73, and 279.74(b), does the processing of the bilge water escape Part 279 standards per §279.11?

No. What escapes Part 279 management [if it meets the used oil spec and the generator complies with §§279.72, 279.73, and 279.74(b)] is “used oil that is to be burned for energy recovery.” According to RO 12738, it is the as-burned used oil that must meet the specification to be unregulated. In this example, it is not the bilge water but the recovered used oil that will be burned for energy recovery. “On-specification used oil that is re-refined…rather than burned for energy recovery, is subject to all applicable requirements of Part 279.” [RO 14110] Thus, bilge water processing would be subject to Part 279, Subpart F standards.

Although its management is outside of RCRA, on-spec used oil is still subject to other applicable regulations. For example, on-spec used oil stored in USTs may be subject to Part 280 requirements and used oil transport must comply with DOT rules. Also, facilities handling on-spec used oil may be required to prepare and implement SPCC plans. In addition, when an action is taken at the generating facility that may affect the chemical or physical properties of the on-spec used oil, that oil must be reevaluated in terms of the specification. [RO 14110] On-spec used oil that will be processed/re-refined or disposed, rather than burned for energy recovery, remains subject to Part 279 standards. [RO 14110]

Also note that on-spec used oil that contains PCBs at a concentration between 2 and 50 ppm and that will be burned for energy recovery is subject to certain marketer and burner requirements. These requirements, which come from TSCA—not RCRA, reference some of the standards in Part 279 for marketers and burners of off-spec used oil. “Therefore, by operation of the TSCA rules, used oil that is on-specification under the RCRA rules may nevertheless be subject to certain requirements specified in the RCRA rules for off-specification used oil…. The fact that the TSCA rules incorporate by reference these RCRA standards does not mean that PCB-containing [on-spec] used oil is regulated under RCRA authority or that such used oil is off-specification as defined by Part 279.” [68 FR 44661; see also RO 14117] Specifically, burners of on-spec used oil containing between 2 and 50 ppm PCBs must comply with a number of the Part 279, Subpart G requirements, including restrictions on burning, notification, certification, tracking, and recordkeeping, in addition to requirements specified in §761.20(e)(3–4).

Used oil generators that burn their own on-spec used oil for energy recovery in onsite boilers or industrial furnaces (i.e., without complying with the off-spec burner requirements in Part 279, Subpart G) are, by definition, used oil fuel marketers. In order to avoid the Subpart G burner standards, they must determine that their used oil meets the used oil fuel specification. That makes them a marketer per §279.70(a)(2). [RO 14280]

For CAA purposes, on-spec used oil is not solid waste when combusted

In response to court decisions, EPA had to rework two Clean Air Act (CAA) rules: 1) the commercial and industrial solid waste incineration (CISWI) rule, and 2) the industrial boilers maximum achievable control technology (MACT) rule. The court concluded that the agency erred by excluding some units that combust solid waste for the purpose of energy recovery from the CISWI rule, instead regulating these units under the boiler MACT rule.

As EPA revised these two air rules for repromulgation in accordance with court mandates, the agency was obligated to articulate which nonhazardous secondary materials constitute “solid waste” under RCRA, since the CAA requires that these rules be based (in part) on that definition. Any unit combusting any solid waste must be regulated as a CISWI unit, regardless of whether the material is being burned for energy recovery or destruction. Conversely, if a nonhazardous secondary material is not a solid waste under RCRA, then any unit combusting that material will be subject to other CAA standards, such as the boiler MACT rule.

In a March 21, 2011 final rule [76 FR 15456], EPA determined that on-spec used oil meets the definition of a traditional fuel and is, therefore, not solid waste when used in a combustion unit. (Of course, it would be a solid waste if discarded.) [§241.2] Thus, burning on-spec used oil will not subject a combustion unit to CISWI standards, but other CAA controls, such as the boiler MACT rules, may apply.

Burning off-specification used oil

Facilities that combust used oil not meeting the §279.11 fuel specification face a much different outlook than their counterparts that burn on-spec oil. Burning off-spec used oil subjects a facility to the burner standards in Part 279, Subpart G. Those standards limit the types of units in which off-spec used oil may be burned and impose additional requirements on such facilities.

Allowable units

Off-spec used oil may be burned only in a boiler or industrial furnace as defined in §260.10, utility boiler, or RCRA hazardous waste incinerator. In the case of a boiler or industrial furnace, such units do not have to be BIFs subject to regulation under Part 266, Subpart H; they simply must meet the definition of boiler or industrial furnace in §260.10. [57 FR 41599] Hazardous waste incinerators, of course, must be in compliance with Part 264/265, Subpart O. There is one exception to the general rule stated above, which we address in the next subsection.

The four types of units noted above that are allowed to burn off-spec used oil address EPA’s air emission concerns. These units typically use high-efficiency boilers, have significant air pollution controls associated with them, and often are not located in residential areas.

The agency has noted in guidance that facilities do not have to analyze their used oil to see if it meets the fuel specification if it will be combusted for energy recovery or incineration in one of the units noted in the paragraph above. They may simply voluntarily assume it is off-spec and choose to meet the Part 279, Subpart G requirements for burning off-spec used oil. [RO 11811] This would be similar to a generator of solid waste declaring its waste to be hazardous (in lieu of analyzing it) and managing it as such.

The space heater exception

A used oil generator may burn off-spec used oil onsite in space heaters, without complying with the Part 279, Subpart G burner standards, provided [§279.23]:

  • Only used oil that the facility generates or receives from household DIYs is burned in such heaters,
  • The space heater is rated at not more than 0.5 million Btu/hr, and
  • Combustion gases from the space heater are vented to ambient air.

Generators taking advantage of this exception do not have to determine (analyze) whether the used oil meets the fuel specification. Also, a very small quantity generator (VSQG) could burn a mixture of its used oil and hazardous waste that is exempt per §§262.13(f)(1)(iii) and 279.10(b)(3) in such onsite space heaters whether or not the mixture meets the used oil specification.

Note that an onsite space heater that exceeds the Btu capacity limit given above is considered a nonindustrial boiler. Thus, the owner/operator is prohibited from burning off-spec used oil in such a unit. [RO 14280] See Case Study 1 for an example of the applicability of this exception.

Case Study 1

Off-spec used oil burner requirements

Per Part 279, Subpart G, facilities that burn off-spec used oil must meet a number of conditions. They must:

  • Obtain an EPA ID number;
  • Document or determine whether the halogen content of the used oil they burn is above or below 1,000 ppm and, if above, rebut the presumption that the used oil has been mixed with a hazardous waste;
  • Store used oil only in tanks, containers, or RCRA units;
  • Provide secondary containment for containers and aboveground tanks used to store used oil;
  • Label tanks, containers, and UST fill pipes “Used Oil”;
  • Respond to releases of used oil;
  • Report releases of used oil contaminated with hazardous substances in excess of CERCLA reportable quantities and releases that violate water-quality standards or create a sheen on surface water;
  • Keep records of each shipment of used oil accepted for burning; and
  • Before accepting the first shipment from a supplier, certify that EPA has been notified and that oil will only be burned in §260.10 boilers and industrial furnaces, utility boilers, or hazardous waste incinerators.

For CAA purposes, off-spec used oil is solid waste when combusted

EPA issued a rule on March 21, 2011 [76 FR 15456] to delineate which nonhazardous secondary materials are solid waste under RCRA when combusted. Any unit combusting any solid waste must be regulated under the CAA as a CISWI unit, regardless of whether the material is being burned for energy recovery or destruction. EPA determined in the March 2011 rule that off-spec used oil is a solid waste, because it contains higher levels of contaminants than traditional fuels. [76 FR 15502, RO 14895] Thus, units burning off-spec used oil (other than small space heaters) will be subject to CISWI standards.

Although off-spec used oil is a solid waste when combusted as noted above, it can be processed (under the Part 279, Subpart F provisions for processors and re-refiners) to meet the §279.11 used oil fuel specification. Once it is on-spec, it will no longer be solid waste if combusted. [§241.3(b)(4)]

Burning used oil-contaminated and derived materials

Materials that contain or are contaminated with used oil are regulated as used oil if they are burned for energy recovery. [§279.10(c)(2), 57 FR 41585] This applies regardless of whether the materials contain visible signs of free-flowing oil. For instance, hydraulic fluid filters and other used oil filters are regulated under Part 279 if they are burned for energy recovery, regardless of the degree of oil removal. [RO 11808] Similarly, sorbents containing used oil (without any free-flowing oil visible) are subject to the Part 279 used oil regulations if they are to be burned for energy recovery. [RO 11798] However, EPA has provided a caveat:

“[S]ome sorbents have a high [Btu] value and once contaminated with used oil are managed by burning for energy recovery and, therefore, are regulated under Part 279. Contaminated materials (after draining) which provide little or no energy when burned, such as soil or clay-based sorbents, are not subject to Part 279. Whether a material is ‘burned for energy recovery’ depends on the type of materials being burned and the combustion equipment being used. For purposes of the EPA regulations governing boilers and industrial furnaces, burning for energy recovery is limited to materials that have a heating value of at least 5,000 Btu/pound…. EPA believes it is reasonable and consistent with the regulations to apply the same interpretation under Part 279. Of course, an authorized state may interpret what constitutes ‘burning for energy recovery’ more stringently than EPA and that interpretation could be controlling….” [RO 14111]

Used oil fuel marketer requirements

Besides regulating used oil burned for energy recovery, Part 279 also addresses used oil fuel “marketers.” Any entity that conducts one of the following two activities is subject to Subpart H requirements as a used oil fuel marketer:

  1. Directs a shipment of off-spec used oil from their facility to a used oil burner; or
  2. First claims that used oil to be burned for energy recovery meets the used oil fuel specification.

Subpart H does not apply to used oil generators and transporters who send shipments of off-spec used oil to processors, even if such processors incidentally burn used oil. The marketer regs also don’t apply to persons who direct shipments of on-spec used oil, but are not the first person to claim the oil meets the specification.

Note that used oil generators that burn their own on-spec used oil for energy recovery in onsite boilers or industrial furnaces (i.e., without complying with the Part 279, Subpart G requirements) are, by definition, used oil fuel marketers. In order to avoid the Subpart G burner standards, they must determine that their used oil meets the used oil fuel specification. That puts them into the marketer category via the second activity above. [RO 14280]

The applicability requirements, management standards, and other Part 279 provisions that apply to used oil fuel marketers are shown in Figure 2.

Figure 2 Figure 3a Figure 3b

Used oil fuel marketer requirements focus on analytical results, tracking, and recordkeeping. Specifically, marketers must:

  • Obtain an EPA ID number;
  • Ensure that off-spec used oil is shipped only to used oil burners who: 1) have an EPA ID number, and 2) plan to combust that oil in a §260.10 boiler or industrial furnace, utility boiler, or hazardous waste incinerator;
  • Obtain a certification of compliance from the burner prior to the first shipment of off-spec used oil to that party; and
  • Maintain records of: 1) on-spec used oil analyses, and 2) shipments of on-spec and off-spec used oil. Marketers must only keep records of shipments to the initial facility to which they deliver the oil. [§279.74(b), 68 FR 44662] Marketers are not required to maintain records of subsequent transfers of this used oil to other entities.

For example, a service station that generates used oil to be burned for energy recovery and claims that it meets the fuel specification is a used oil fuel marketer. The facility must obtain an EPA ID number and test the oil to show that it is on-spec. These requirements must be met prior to the used oil being shipped offsite as on-spec—the oil cannot be shipped under the assumption that it is or will be blended into on-spec used oil. [RO 14110] Finally, the service station must maintain records of used oil analyses and on-spec oil shipments. Conversely, if the service station simply sends the used oil it collects to a used oil recycler, the station would be a used oil generator—but not a used oil fuel marketer—and the marketer requirements would not apply.

Although the second bullet above seems to imply that marketers can ship used oil only to used oil burners, they in fact can ship used oil to burners, processors, or other marketers. [RO 14755]

Section 761.20(e)(2) requires marketers (and burners) to presume that used oil to be burned for energy recovery contains >2 ppm PCBs and is, therefore, subject to the TSCA requirements in §761.20(e). The presumption can be overcome if a marketer determines through testing or “other information” that the used oil contains <2 ppm PCBs. [RO 14606] (“Other information” consists of personal knowledge of the source and composition of the used oil, or a certification that the used oil contains <2 ppm PCBs from the person generating the used oil. [§761.20(e)(2)(iii)]) If the used oil contains between 2 and 50 ppm PCBs, marketers must comply with a number of Part 279, Subpart H requirements, including notification, certification, tracking, and recordkeeping, in addition to the requirements specified in §761.20(e)(1) and (4). [68 FR 44661, RO 14117]

In guidance, EPA noted that the frequency of testing used oil to ensure it meets the fuel specification depends on a number of site-specific considerations. For example, if some action, mixing, or storage conditions affect the physical or chemical composition of the used oil, a marketer must reevaluate whether it meets the specification. [RO 14110, 14626] Entities making a claim that used oil meets the fuel specification should provide documentation of testing and sampling methods used as well as the frequency of sampling/testing in the facility’s records. [September 10, 1992; 57 FR 41597]


Topic: What Are Universal Wastes?

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This document addresses issues of a general nature related to the federal RCRA regulations. Persons evaluating specific circumstances dealing with the RCRA regulations should review state and local laws and regulations, which may be more stringent than federal requirements. In addition, the assistance of a qualified professional should be enlisted to address any site-specific circumstances.