July 14, 2020

Definition of D001 Hazardous Waste Modernized

On July 7, 2020, EPA finalized an update to the RCRA characteristic of ignitability found in §261.21. [85 FR 40594] While not a major overhaul of the definition of a D001 waste, the final rule addresses four aspects of how to make such a hazardous waste determination by:

  1. Updating the SW–846 test methods for measuring the flash point of a liquid,
  2. Codifying existing guidance on the definition of “aqueous” as it pertains to the alcohol-content exclusion,
  3. Updating the cross-references to DOT hazardous materials regulations, and
  4. Allowing the use of non-mercury thermometers for several SW–846 test methods.

The final rule is very similar to the 2019 proposed rule [84 FR 12539] with one exception—it does not codify existing guidance on sampling multiphase wastes. However, the preamble to the final rule does provide extensive guidance on this topic. The preamble also details EPA’s latest position on the use of the pressure filtration technique specified in SW–846 Method 1311 for assessing the presence of an ignitable liquid versus using the paint filter liquids test (Method 9095).

Updating Flash Point Test Methods

SW–846 Methods 1010A and 1020B (Pensky-Martens and Setaflash flash point test methods, respectively) are updated to 1010B and 1020C. The update allows for the use of newer ASTM standards (D8175-18 and D8174-18, respectively), while retaining the older ASTM standards (D93-79 or D93-80 and D3278-78). Thus, between Methods 1010B and 1020C, there are now five test methods that can be used for measuring flash point to determine ignitability of liquids. According to EPA, “generators are not required to use all of the ASTM standards specified in EPA Methods 1010B and 1020C when making a hazardous waste determination on a specific waste.... [T]he generator should use the test method most appropriate for their waste based on knowledge of the waste.” [85 FR 40598] While the older standards represented the best practices and technologies in 1980, scientific and technological advances have made these methods outdated. The newer methods allow for improved electric-spark ignition devices, newer heating elements, and the use of non-mercury thermometers. This change does not impact how a generator will make a D001 characterization, but it will affect how an analytical testing lab performs its tests.

Codifying “Aqueous” Guidance in the Alcohol-Content Exclusion

Section 261.21(a)(1) contains an exclusion for aqueous wastes containing less than 24% alcohol. The final rule revised this exclusion by defining aqueous as “at least 50 percent water by weight.” EPA uses alcoholic beverages and aqueous latex paints as examples of how this exclusion could apply. These materials exhibit low flash points due to their alcohol content but do not sustain combustion because of their high water content. If a waste is similar in nature to one of these materials, it could be an indicator the waste is eligible for the exclusion. Although EPA did not finalize any other changes to the alcohol-content exclusion other than as noted above, the agency stated “a generator should consider the regulatory language itself as well as guidance that the agency has provided in the past.” For example, previous agency guidance in RO 13548 noting that an ignitable waste containing 77% water, 13% alcohol, and 10% non-alcohol liquid is eligible for the exclusion is still valid. [85 FR 40600] Though not codified, the agency also reiterated that the exclusion extends to wastes containing non-ethanol alcohols.

Updating DOT Cross-References

Sections 261.21(a)(3) and (4) define certain ignitable compressed gases and oxidizers, respectively, as D001 wastes based on language in the DOT regulations. The final rule removes obsolete DOT references and replaces them with current citations. Ignitable compressed gases [see §261.21(a)(3)(ii)(A)] are now identified using the current Division 2.1 flammable gas language in 49 CFR 173.115(a), while ignitable aerosol wastes will be designated as D001 per §261.21(a)(3)(ii)(B) if they meet the criteria in 49 CFR 173.115(l). One way to determine if you have one of these wastes is by looking at its DOT hazardous materials hazard class/division. If the waste you are shipping down the road is a DOT Division 2.1 flammable compressed gas, then it is a D001 ignitable compressed gas. The definition of an oxidizer as a D001 ignitable waste now correctly excludes DOT Division 1.1, 1.2, and 1.3 explosives. [§261.21(a)(4)(i)(A)] If the waste you are shipping down the road is a DOT hazard class 5.1 oxidizer or 5.2 organic peroxide, then it is a D001 oxidizer. In this final rule, Note 4 at the end of §261.21, which said that an organic peroxide is a type of oxidizer, was deleted. As a result, it is less clear in the regulations that organic peroxides are D001 when disposed. Additional clarification from EPA would be helpful.

Allowing the Use of Non-Mercury Thermometers

Numerous test methods, including the old flash point test methods, require the use of mercury thermometers. As part of its strategy for phasing out the use of mercury thermometers due to environmental, health, and safety concerns, EPA has modified SW–846 air sampling and stack emissions Methods 0010, 0011, 0020, 0023A, and 0051, as well as flash point Methods 1010B and 1020C, to allow the use of non-mercury thermometers. The final rule incorporated these test method revisions into §260.11 and Part 261, Appendix IX as appropriate.

Evaluating Multiphase Wastes

Section 262.11(a) states that a hazardous waste determination must be made at the point of generation and at any time in the course of its management that the waste has, or may have, changed its properties in a way that may impact its classification under RCRA. EPA’s long-standing sampling guidance states that for multiphase wastes, a sample should be separated into phases and each individual phase analyzed appropriately for the characteristic of ignitability. [RO 13759, 14834] Although proposed, the final rule did not codify this concept. Instead, the rule preamble [85 FR 40600–3] provided considerable discussion on how to make an ignitability characteristic determination for multiphase wastes, as summarized below:

Pressure Filtration Technique vs. Paint Filter Liquids Test

In previous guidance, EPA had noted that the pressure filtration technique specified in Method 1311 was the definitive procedure for determining if a waste contains a liquid. [January 13, 1995; 60 FR 3092] And the agency had website guidance (since deleted) noting that if the paint filter liquids test does not produce free liquid, the generator must use the pressure filtration test. In the preamble to the July 2020 rule, EPA appears to have backed away from its previous guidance, opening the door for the use of the more-common paint filter liquids test for determining the presence of a liquid when making an ignitability determination:

Effective Date and State Adoption

The rule is effective in Alaska and Iowa on September 8, 2020. The final rule is promulgated under the base RCRA program, meaning the changes do not take effect in RCRA-authorized states (all states other than Alaska and Iowa) until the states adopt them. Moreover, the revisions to the test methods are considered to be neither more nor less stringent than the existing regulations; thus, authorized states may, but are not required to, adopt these changes. [85 FR 40605]


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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.