EPA Updates Rule on Determination of Ignitable Hazardous Waste


Main Content

EPA Updates Rule on Determination of Ignitable Hazardous Waste

By: Nick Petruzzi, PE, CPG

A solid waste is considered a hazardous waste if it is associated with a listing or a characteristic.  One of the four possible characteristics of a hazardous waste is ignitability.  The ignitability characteristic (D001) applies to various types of solid waste, one of which is a liquid that exhibits a flash point less than 140o F.  On July 7, 2020, EPA issued a final rule in Federal Register (FR) 40594 to modernize the determination of ignitable liquids, along with other minor changes.  This rule becomes effective on September 8, 2020 and includes the following elements:

  • Test methods to determine flash point of a liquid waste have been updated to include additional ASTM standards, while retaining the existing ASTM standards that are referenced in SW-846 Method 1010A (Pensky-Martens) and SW-846 Method 1020B (Setaflash).  Allowing use of additional ASTM standards provides greater flexibility in the determination of an ignitable hazardous waste and allows phase-out of outdated standards that rely on instrumentation that is no longer readily commercially available. 
  • Air sampling and stack testing using SW-846 Methods 0001, 0011, 0020, 0023A, and 0051 have been updated to allow use of alternative temperature-measuring devices, while retaining the existing method of using a mercury thermometer.  Allowing use of multiple temperature-measuring devices provides greater flexibility and improves worker safety and reduces spill cleanup costs associated with the use of mercury thermometers.
  • Previous guidance that defined “aqueous” as “at least 50 percent by water weight” has been codified for the purpose of clarifying 40 CFR 261.21(a)(1), which pertains to properties of characteristically ignitable liquids.
  • Various conforming amendments to other parts of the CFR are being finalized for consistency with the above changes.

There were also elements within the proposed rule that did not get incorporated into the final rule: provisions related to a revised definition of alcohol in association with the aqueous alcohol exclusion; codifying guidance related to sampling requirements for mixed waste; and incorporation of the application of the Pressure Filtration Test in identifying ignitable liquid waste.  Final action was not taken on these elements based on a significant number of public comments which made compelling arguments that the proposed rules would cause confusion rather than clarification.  The agency may seek additional public comment on some of these elements in the future.    

The final actions that will become effective on September 8, 2020 are considered no more and no less stringent than existing rules.  Therefore, authorized states may, but are not required to, adopt the changes. 


Nick M. Petruzzi, PE, CPG is a Principal Engineer at Cox Colvin & Associates, Inc. Mr. Petruzzi holds degrees in both geology and environmental engineering. He has been involved with numerous projects that have required the evaluation, design, construction, and operation of both established and innovative remedial alternatives for the treatment and disposal of contaminated soil and groundwater at industrial facilities. He also provides management and technical services on projects that deal with hydrogeologic investigation as well as hazardous waste, NPDES, and air permits. Mr. Petruzzi was a contributing author and instructor for the Interstate Technology and Regulatory Council (ITRC) Green and Sustainable Remediation (GSR) team, is a registered Professional Engineer in the State of Ohio, Kentucky, and Pennsylvania, and is a Certified Professional Geologist.