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Final Rule: Modernizing Ignitable Liquids Determinations

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Rule Summary

EPA finalized changes to the hazardous waste regulations that modernize how the hazardous waste characteristic of ignitability is determined under the Resource Conservation and Recovery Act. The final rulemaking allows the use of non-mercury thermometers in a variety of EPA’s analytical methods that currently require mercury thermometers. These final amendments also allow for the use of modern equipment and techniques for making ignitability determinations for waste. In addition, these changes reduce potential mercury exposures to humans and the environment by reducing the overall use of mercury-containing products.  

This rule also finalized the codification of existing guidance to define “aqueous” as “50% water by weight.” EPA did not finalize other guidance proposed for codification and instead explained in preamble how existing guidance for the aqueous alcohol exclusion and sampling of multiple phase wastes applies to provide clarity and more certainty for the regulated community.

It is expected that the implementation of these new and improved methods will not affect the analytical results when compared to the current methods. The rulemaking relied on studies conducted by the American Society for Testing and Materials (ASTM), the National Institute of Standards & Technology, and others that confirm this.

EPA sought input from waste generators, laboratories, state officials, trade associations and members of the public on the proposal in a 60-day comment period that ended on June 3, 2019. EPA carefully considered all the public comments before issuing the final rulemaking, which was signed on June 8, 2020.

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Rule History

The ignitability characteristic was originally proposed in 1978, finalized in 1980 and revised in 1981. These regulations were included in 40 CFR Parts 260 and 261, and they defined the ignitability characteristic and incorporated Pensky-Martens and Setaflash as the required tests for ignitable hazardous waste determinations.

ASTM committees updated these test methods multiple times to improve the standards and incorporate modernized technology practices, but the RCRA regulations still require the use of the test methods listed in the 1980 and 1981 regulations.

Due to the scientific and technological advances over the last few decades, certain test methods became outdated, and their use presents several challenges to the regulated community. This final rulemaking provides flexibility and cost savings to the regulated community by allowing the use of additional test procedures that use more readily available, modern laboratory equipment.

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Additional Resources

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