U.S. EPA Issues Proposed Rule for Ignitable Liquid Determinations

Posted on: April 22, 2019

by Cora Knutson


photo of ignitable chemicals - Learn what the EPA is proposing for regulations impacting ignitable chemicalsEarlier this month, the U.S. EPA requested public comment on a proposed rule regarding ignitable liquids under the Resource Conservation and Recovery Act (RCRA).  The current regulation requires test methods mandating the use of mercury-containing thermometers, references out of date standards, and contains certain ambiguous language for which guidance was issued.  The proposed rule updates test methods for determining whether a waste is an ignitable hazardous waste and codifies previously issued guidance.  Comments must be received on or before June 3, 2019.

The EPA does not expect the other parts of this proposed action (i.e., changes to aqueous alcohol exclusion, addition of sampling guidelines for multiphase mixtures, and technical edits) to affect any entity because they do not create new requirements or change existing requirements.

Further Information

Under RCRA, solid waste is ‘‘any garbage, refuse, sludge from a waste treatment plant, water supply treatment plant, or air pollution control facility and other discarded material, including solid, liquid, semisolid, or contained gaseous material…”

The EPA considers certain of these wastes hazardous – those that generators determine exhibit ignitability, corrosivity, reactivity, or toxicity or that are specifically listed by the EPA.  It is several aspects of the ignitability classification regulations that EPA is addressing in the proposed rule:

    1. Existing regulations require the use of Test Methods for Evaluating Solid Waste: Physical/Chemical Methods (SW–846) Methods 1010A (Pensky-Martens) or Method 1020B (Setaflash) for flash point testing and Methods 0010, 0011, 0020, 0023A, or 0051 for air sampling and stack emissions. These Methods required the use of mercury thermometers.Methods 1010A and 1020B incorporate by reference certain American Society for Testing Materials (ASTM) standards which are no longer current.  Method 1010A incorporates ASTM D 93-79 and D 93-80 (issued in 1979 and 1980) whereas the current ASTM D 93-16 standard was published in 2016. Method 1020B incorporates ASTM D 3278-78 (from 1978) while the current standard was last edited in 1996 and confirmed in 2011.  Further, both ASTM D 93 and ASTM D 3278 standards were developed for use with petroleum products.

      Under the proposed rule, updated test methods allow for both digital and non-mercury liquid in glass flash point detection methods.  Updated SW-846 Methods 0010, 0011, 0020, 0023A, and 0051 are incorporated by reference.

      The EPA has worked with the ASTM International Committee on Waste Management to develop test method standards specifically for waste, and these new standards, ASTM D 8175-18 (“Test Method for Finite Flash Point Determination of Liquid Wastes by Pensky-Martens Closed Cup Tester”) and ASTM D 8174-18 (“Test Method for Finite Flash Point Determination of Liquid Wastes by Small Scale Closed Cup Tester”) are incorporated into the updated SW-846 Methods 1010B and 1020C. Generators and laboratories should choose to use the test method that is most suitable to their needs.

      The EPA may require transition to the newer Methods and Standards at some point, but, at this time, the use of the older Methods and Standards will still be permissible, allowing effected entities to transition to the newer Methods and Standards on their own schedule.  The public is encouraged to comment on whether immediate transition should be required.


    1. Existing regulations are somewhat unclear regarding aqueous solutions containing low amounts of alcohol, and reference Department of Transportation (DOT) regulations that are no longer current. The intent of the aqueous solutions exclusion was to exclude from ignitability classification those solutions that will not sustain combustion because of their high water content.  Guidance has clarified this somewhat.Under the proposed rule, the EPA will rephrase this exclusion as “other than a solution containing less than 24 percent of any alcohol or combination of alcohols (except if the alcohol has been used for its solvent properties and is one of the alcohols specified in EPA Hazardous Waste No. F003 or F005) by volume and at least 50 percent water by weight.” The EPA notes that water content may be quantified in different ways including SW-846 Methods 9000 and 9001, as appropriate.

      The above phrasing for the exclusion may allow for the inadvertent exclusion of wastes that are ignitable due to non-alcohol components.  The public is encouraged to comment on any known waste streams for which this could be the case, how these are currently managed, and any hazards or lack thereof associated with the waste or its handling.


    1. Existing guidance on multi-phase waste specifies that testing should be done on each phase to the extent possible. The EPA has proposed pressure filtration (SW-846 Method 1311) to confirm that a waste does not contain liquid.Under the proposed rule, Codified language will indicate that multi-phase waste is to be separated into its different liquid and solid phases to the extent possible before then testing each phase for ignitability.  The EPA suggests SW-846 Methods 9095B or 1311 to confirm that a waste does not contain liquid.  The public is encouraged to comment regarding the determination of free liquids.


  1. Existing regulations reference DOT regulations that are obsolete.Under the proposed rule, Regulations will now reference ASTM E 681-85 (“Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and gases).”) as the modified DOT regulations require, mirror DOT requirements, and remove references to the Bureau of Explosives as this is no longer the delegated authority.

How will this impact me?

Consider whether your state already has an authorized RCRA program.  The proposed rule, if finalized, would be required only in states that do not yet have final authorization of their base RCRA programs as these changes in the rule are neither considered more nor less stringent, nor are broader in scope than the previous regulations. Authorized states may, but are not required to, adopt the changes in the rule.

If you are a generator of waste or a laboratory, consider adjusting testing procedures as soon as reasonably possible as the use of mercury thermometers will no longer be accepted at some point (possibly as soon as this rule is finalized).

If already following EPA guidance for aqueous solutions and multi-phase wastes, the codification of these will likely have minimal impact.  If not following the guidance, now is the time to move toward that goal.

Similarly, if following DOT regulation, the update to EPA references may have minimal effect.

Next steps

Comment on the proposed rule and review the new/updated Standards and Methods.


The full proposed rule and supplementary information can be found at FR Doc. 2019–05878.

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