EPA Seeks Input on Potentially Important Changes to “SW-846” Waste Sampling and Testing Methods

On September 14, 2026, the U.S. Environmental Protection Agency (EPA or the Agency) issued a Request for Information (RFI) to help the Agency decide whether to revise or supplement its “Test Methods for Evaluating Solid Waste” under the Resource Conservation and Recovery Act (RCRA), commonly known by its EPA publication number, “SW-846.” See 91 Fed. Reg. 58,117 (September 14, 2026). Although this RFI might be overlooked or dismissed as a minor technical matter, it could have important implications for the scope of the RCRA hazardous waste regulatory program and related matters, such as site remediation. 

The RFI highlights a few specific topics on which EPA is seeking comment from industry, researchers, academia, non-governmental organizations, and government entities at the federal, state, and local levels. This alert discusses each topic below. Comments are due by November 13, 2026.

Waste Sampling

EPA asks for input on challenges encountered when sampling wastes under SW-846, as well as how to improve the existing sampling guidance. Sampling methods are critically important, since evaluations of wastes generally must be based on a “representative sample,” which is defined under the RCRA regulations as “a sample of a universe or whole … which can be expected to exhibit the average properties of the universe or whole.” See 40 C.F.R. § 260.10. Moreover, SW-846 cautions that “the term ‘representative sample’ can be misleading unless one is dealing with a homogeneous waste from which one sample can represent the whole population. In most cases, it would be best to consider a ‘representative data base’ generated by the collection and analysis of more than one sample that defines the average properties or composition of the waste.” See SW-846, Chapter Nine (Sampling Plans) at NINE-30. 

Because heterogenous wastes pose particular sampling issues, EPA asks specifically about sampling challenges and potential solutions for such wastes. It highlights electronic devices, solar panels, and debris (e.g., from remediation activities) as examples. In this regard, we note that we are aware of situations in which varying methods for sampling multi-component products have produced widely differing test results, leading researchers, government authorities, or industry organizations to develop their own sampling protocols to ensure consistent and reliable results.

Statistical Methods

EPA’s RFI cites the Agency’s 2002 “RCRA Waste Sampling Draft Technical Guidance,” and refers to it as “EPA’s existing guidance on waste analysis plans and waste sampling.” However, when the Agency first issued this draft guidance, a broad multi-industry coalition vigorously objected to it, largely because it included statistical methods for evaluating test results on wastes that bore no relation to the “average properties” of the wastes, as specified under the regulations. For example, under one of these tests, a waste might be deemed hazardous if any individual sample exceeded a regulatory threshold, regardless of any samples below the threshold. 

In 2004, EPA acknowledged the industry objections and stated that it “will be revising the guidance in the near future … to adequately address all scientific and legal concerns with the draft guidance.” See Letter from Matt Hale, Director, Office of Solid Waste, EPA, to Lakeisha R. Harrison, American Petroleum Institute (September 20, 2004) (RCRA Online #14743). The Agency also stressed that “[u]ntil we make a final decision on the guidance, Chapter Nine [of SW-846] is the applicable guidance.” Id. (also underscoring that “[t]he guidance … is still a draft guidance document. There is no reason to ‘withdraw’ the guidance, since it is not a final document”). In the more than 20 years since then, EPA has not followed up on its promise to revise the document. 

Given this history, it is astonishing that the Agency is now referring to the discredited draft guidance as “EPA’s existing guidance.”  The true existing guidance, as EPA previously noted, is Chapter Nine of SW-846.  Moreover, even that guidance is legally dubious, inasmuch as it fails to identify when the “average properties” of a waste can be judged to exceed a regulatory threshold based on a “preponderance of the evidence” (the standard for civil or administrative enforcement) or “beyond a reasonable doubt” (the standard for criminal enforcement).  See generally Aaron H. Goldberg, “Stranger Things in the RCRA Hazardous Waste Regulations,” published in the American Bar Association's Natural Resources & Environment publication (Spring 2026) (section entitled “Lies, Damn Lies, and EPA Statistics”).  

Toxicity Characteristic Leaching Procedure

EPA developed the Toxicity Characteristic Leaching Procedure (TCLP), Method 1311 in SW-846, for purposes of determining (i) when wastes exhibit the toxicity characteristic and thus qualify as hazardous wastes under RCRA, and (ii) whether certain hazardous wastes have been adequately treated to the point where they can be land disposed under the RCRA Land Disposal Restrictions (LDR) program. See 40 C.F.R. § 261.24(a)(1) (use of the TCLP under the RCRA toxicity characteristic) and § 268.40(b) (use for LDR purposes). The test simulates the leaching of hazardous constituents from waste in the presence of a mild organic acid (acetic acid) that may form if a waste is managed or mismanaged within a municipal solid waste (MSW) landfill. 

In the RFI, EPA states that the TCLP may not accurately predict the leaching of hazardous constituents from certain types of wastes (e.g., oily wastes, paint wastes, or highly alkaline wastes), may not reflect certain processes within landfills (e.g., chelation, oxidation/reduction, or leaching over long periods of time), may not mimic conditions in non-MSW landfills (e.g., industrial waste landfills), and may not address pathways other than leaching of hazardous constituents into groundwater that may cause wastes to be toxic to human health or the environment. The Agency therefore asks for comments on problems encountered with use of the TCLP and how the test might be improved. It specifically asks whether the existing requirement that the particle size of the waste be reduced, if necessary, so that it can pass through a 9.5 mm (0.375 inch) sieve, should be modified to include a minimum particle size, because smaller particle sizes correspond to more surface area available for leaching and potentially artificially elevated TCLP test results. EPA also asks whether the existing limits in the TCLP test on use of vacuum filtration, as an alternative to pressure filtration, should be changed.

Other Leaching Tests

EPA has developed four leaching tests other than the TCLP for use in contexts other than disposal of wastes in landfills, such as: (i) evaluating the environmental impacts of beneficially using secondary materials in various applications (e.g., construction materials); (ii) making cleanup decisions under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA); (iii) assessing whether listed hazardous wastes may be “delisted”; and (iv) evaluating the effectiveness of waste treatment technologies. See SW-846, Methods 1313, 1314, 1315, and 1316. The so-called Leaching Environmental Assessment Framework (LEAF) tests consider the impact on leaching caused by varying the leaching medium pH, the ratio of leaching medium to solids, and the form of the waste (e.g., granular or monolithic solids). They are not currently intended for use when the TCLP is specifically required under RCRA regulations, which is the case for making hazardous waste determinations and for determining whether wastes meet applicable LDR treatment standards.

In the RFI, EPA asks for input on whether LEAF methods might be adopted as an alternative to the TCLP when wastes are disposed in landfills other than MSW landfills (which, as noted above, formed the basis for the TCLP). The Agency also asked more broadly about the use of leaching tests other than the TCLP, presumably including non-LEAF tests such as the Synthetic Precipitation Leaching Test (SPLP) (Method 1312), the Multiple Extraction Procedure (MEP) (Method 1320), and the Oily Waste Extraction Procedure (OWEP) (Method 1330).

Other SW-846 Issues

EPA’s RFI is not limited to the topics discussed above. Instead, the Agency asks for more general comments on “SW-846 methods including how they are used, testing challenges, and needs for updates and new methods.” Although EPA does not provide any substantive examples, based on our experience, topics that might be suitable for addressing in comments include the following:

• The absence of SW-846 test methods for ignitable solids or for any of the eight hazardous properties covered by the RCRA reactivity characteristic. See 40 C.F.R. § 261.21(a)(2) and §§ 261.23(a)(1)-(8).
• Ambiguous, conflicting, and confusing statements made by EPA in the 2020 final rule on “Modernizing Ignitable Liquids Determinations” about how wastes with multiple phases (e.g., liquids and solids, or oily and aqueous liquid layers) should be evaluated under the RCRA ignitability characteristic. See generally 85 Fed. Reg. 40,594 (July 7, 2020).
• Whether SW-846 should provide more guidance on the minimum number of samples to collect and analyze when initially characterizing or re-characterizing a waste stream, to ensure the resulting data are sufficient to support reliable statistical analysis, taking into account the waste's variability or heterogeneity.
• Uncertainties about the basis for EPA’s claim that “most lithium-ion … batteries in use today are likely to be hazardous waste due to ignitability and reactivity (D001 and D003)” and how one might determine that certain lithium-ion batteries (e.g., solid-state or fully discharged batteries) are not ignitable or reactive.
• Questions about whether electronic devices containing lithium-ion batteries might be deemed ignitable or reactive based purely on the fact that the batteries inside might be ignitable or reactive. 
• Uncertainties about if/when aerosol cans might qualify as ignitable or reactive hazardous wastes.

Related Developments

EPA is not alone in reconsidering how it evaluates whether wastes are hazardous. Of particular note, in late 2025, the California Board of Environmental Safety approved a state Hazardous Waste Management Plan that included several recommendations to revise its current hazardous waste characteristics – which are already much broader than the federal characteristics under RCRA – to ensure that hazardous wastes are properly identified and managed safely. Based on this recommendation, DTSC is taking several steps, including reevaluating the Waste Extraction Test (WET) used to evaluate wastes under the state’s Soluble Threshold Limit Concentration (STLC) criteria. See 22 Cal. Code Regs. § 66261.24(a)(2) (STLC) and Appendix II to Division 4.5, Chapter 11 (WET); see also Appendix J to the Draft Hazardous Waste Management Plan (“Evaluation of the Waste Extraction Test (WET)”). The WET differs from the TCLP in several respects, including requiring a smaller particle size, a lower ratio of leaching medium to solid waste, and a different organic acid leaching medium (i.e., citric acid rather than acetic acid).

At the international level, parties to the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal (190 countries and the European Union) are actively considering changes to both the list of wastes/constituents in Annex I that are presumptively classified as hazardous under the Convention, as well as the hazardous waste characteristics in Annex III that can be used to overcome any presumptions. Proposals include, but are not limited to, the addition of lithium, cobalt, and nickel (and their compounds) to Annex I. If adopted, such changes would significantly expand the range of wastes subject to stringent prior informed consent approvals from importing, exporting, and transit states, as well as contract, movement document, and financial assurance requirements. In many instances, international shipments of Basel wastes are prohibited. For example, parties are prohibited from trading in Basel-covered wastes with the U.S. (a non-party) absent a separate agreement under Article 11 of the Convention. Negotiations on possible revisions to Annex I resume in an Expert Working Group that will meet from September 27-29, 2026, in Geneva. Separate negotiations are underway to clarify the classification and management of e-waste and waste batteries. A prior B&D news alert, “China and Europe Diverge on Classification of Black Mass from Recycling of Lithium-Ion Batteries,” discusses varying approaches countries have taken to classifying LIBs and black mass.

For more information about EPA’s RFI and waste evaluation under RCRA and other regulatory programs more generally, please contact Aaron Goldberg or any other member of Beveridge & Diamond's Waste and Recycling practice group. Before joining the firm in 1987, Aaron was EPA’s lead consultant in developing the final rule that revised the RCRA toxicity characteristic, in part by incorporating the TCLP. He was later a leading member of the multi-industry effort opposing EPA’s Draft Technical Guidance on waste sampling. Aaron regularly assists clients in assessing the potential hazards of their wastes, drawing on his advanced degree in chemistry and past experience with EPA.

The firm’s Waste and Recycling practice group assists clients across a wide range of industrial sectors with solid and hazardous waste regulatory issues under RCRA, its state counterparts, international treaties, and the laws and regulations of countries around the world. We regularly help clients classify their wastes as hazardous or non-hazardous, determine whether materials are wastes in the first instance, and assess the potential applicability of regulatory exclusions or exemptions. We have served as lead counsel in many cases challenging key portions of EPA’s definition of solid and hazardous wastes under RCRA, and we defend companies in related enforcement actions.