SUPPLEMENTARY INFORMATION:

I. Public Participation

Written Comments

Submit your comments, identified by Docket ID No. EPA-HQ-OLEM-2026-7360, at www.regulations.gov (our preferred method), or the other methods identified in the ADDRESSES section. Once submitted, comments cannot be edited or removed from the docket. The EPA may publish any comment received to its public docket. Do not submit to EPA's docket at www.regulations.gov any information you consider to be Confidential Business Information (CBI), Proprietary Business Information (PBI), or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission ( i.e., on the web, cloud, or other file sharing system). Please visit www.epa.gov/​dockets/​commenting-epa-dockets for additional submission methods; the full EPA public comment policy; information about CBI, PBI, or multimedia submissions; and general guidance on making effective comments.

Comments containing references, studies, research, and other empirical data that are not widely published should include copies or electronic links of the referenced materials. No confidential and/or business proprietary information, copyrighted information, or personally identifiable information should be submitted in response to this RFI. Privacy note: All comments received from members of the public will be available for public viewing on ( printed page 58118) Regulations.gov. In accordance with FAR 15.202(3), responses to this document are not offers and cannot be accepted by the Federal Government to form a binding contract. Additionally, those submitting responses are solely responsible for all expenses associated with response preparation.

II. General Information

What is the purpose of this RFI?

The work supports the Agency's ability to: foster new technologies for managing waste, recovering resources and reducing environmental impact such as is covered under the Resources Conservation and Recovery Act (RCRA) section 8001; and conduct comprehensive studies on specific solid and hazardous waste streams as covered under RCRA section 8002. The work will be used to consider updates to EPA's Tests Methods for Evaluating Solid Waste (SW-846), which provides the official analytical methods for characterizing hazardous wastes under RCRA. RCRA section 2002 authorizes updates to test methods and waste sampling guidance.

III. Background

The SW-846 Compendium is the official collection of test methods for compliance with RCRA and includes more than 220 sampling and analytical methods for project planning, sample collection and quality control. SW-846 methods are used for RCRA hazardous waste identification and treatment and for contaminated site assessment and cleanup under RCRA and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), emergency response work, the Underground Storage Tanks program, and the Brownfields program.

SW-846 methods updates are necessary to keep up with scientific advances, new equipment, changing technology, and new analytical needs to remain useful. Analytical methods updates can also reduce costs for identification and/or treatment of hazardous waste or for cleanup of contaminated sites.

A few SW-846 methods are incorporated by reference in federal RCRA regulations—they are either required for RCRA compliance testing, or the results are definitive for determining the regulatory status of a waste ( e.g., Method 1311 Toxicity Characteristic Leaching Procedure for toxicity characteristic hazardous waste). Some methods are also incorporated by reference in other regulations: e.g.,40 CFR part 761 TSCA PCB cleanup and disposal and 40 CFR part 503 Biosolids. Most SW-846 methods, however, are published as guidance ( i.e., “non-regulatory methods”).

The Agency uses the Toxicity Characteristic Leaching Procedure (TCLP) to estimate the potential for wastes to leach hazardous constituents to groundwater, where they may be transported to a drinking water well, which may in turn result in human exposure to the toxic constituent. TCLP is designed to reflect conditions likely to occur in a municipal solid waste (MSW) landfill, as the Agency identified industrial waste co-disposal in an MSW landfill as plausible management for unregulated waste.

In 1980, prior to development of the TCLP, the Agency adopted the Extraction Procedure (EP) to identify wastes likely to leach hazardous concentrations of particular toxic constituents into the groundwater under conditions of improper management (45 FR 33110 May 19, 1980). In 1986, the Agency proposed a modified leaching procedure, the TCLP, to replace the EP (51 FR 21648, June 13, 1986). The Agency promulgated the final rule on the application of the TCLP in 1990 (55 FR 11827, March 29, 1990).

In 1991 and 1999, the Science Advisory Board (SAB) reviewed the Agency's leaching evaluation methodology and expressed concern about the widespread non-regulatory use of TCLP, including for estimating leaching under conditions that are substantially different from the conditions built into TCLP (such as contaminated sites). The SAB recommended that EPA develop a new, flexible methodology that can more accurately estimate leaching under a broader range of conditions.

In 1998, the EPA proposed (63 FR 25430 May 8, 1998) that some of the required uses of SW-846 methods were not necessary. In addition, members of the regulated community requested the opportunity to use other reliable methods to comply with RCRA. The Methods Innovation Rule (70 FR 34538 June 14, 2005) removed most required uses of SW-846 methods and allowed more flexibility in test method selection. The rule allowed laboratories to use non-SW-846 methods, provided the facility or laboratory demonstrates the data are of appropriate quality to limit the risk of making decision errors and ensure that waste management decisions are protective of human health and the environment. All SW-846 methods were covered by this rule except for methods that involve determination of method-defined parameters (MDPs), such as TCLP, which must be followed for regulatory compliance.

In 2016, EPA further streamlined the approval process for non-regulatory methods in SW-846 (81 FR 66276, September 27, 2016).

To address the SAB concerns, EPA initiated a program to identify and validate a next generation of leach testing approaches. The Leaching Environmental Assessment Framework (LEAF) analytical methods (SW-846 Methods 1313, 1314, 1315, 1316) were designed to consider the impact on leaching of waste forms and environmental conditions that are known to affect leaching, and which vary in value for different wastes and disposal conditions. The published LEAF methods have only been validated for inorganic chemicals. EPA is currently conducting research and development to adapt the leaching methods to address organic constituents as well.

LEAF is intended for situations where an assessment tailored to site conditions is needed where the conditions differ from the disposal scenario addressed by TCLP, and TCLP is not required by RCRA regulations (that is, the waste is not subject to land disposal restrictions (LDR) treatment requirements that rely on TCLP or is not RCRA hazardous waste). These uses include delisting, beneficial use assessments, and treatment effectiveness evaluations.

IV. Request for Information

EPA has identified some key information categories on which stakeholder insights would be most helpful:

• Waste Sampling
• TCLP
• LEAF
• Other SW-846 Method Needs, Uses, and Issues

Following each information category, EPA has included a list of suggested questions as a helpful guide for consideration in preparing comments. EPA provides these questions simply to guide the type of comments the Agency would find useful to help inform development, updates, and prioritization of methods and guidance. EPA also requests that commenters include, wherever possible, supporting data or other qualitative information such as information about the barriers and challenges to performing the methods, successful guidance and use of methods, and details on measurable benefits for industry, government, or consumers. ( printed page 58119)

A. Waste Sampling Challenges, Best Practices and EPA Guidance

The suggested questions below provide an opportunity for all commenters to provide input on sampling guidance challenges and best practices. EPA is particularly interested in collecting information on sampling and testing of heterogeneous wastes, such as discarded solar panels, that may be particularly challenging for making hazardous waste determinations. EPA is also interested in any existing studies or reports with background information on updated waste sampling procedures. Suggested questions to consider for comment submission include:

• What challenges or barriers does your organization face regarding waste sampling?
• Which types of wastes or waste properties present the biggest challenges related to sampling, and why?
• Does your organization currently manage heterogeneous wastes such as debris, multi-component electronic devices, solar panels or other wastes that present a particular challenge with regard to sampling for the purpose of compliance with RCRA Subtitle C regulations? If so, how does your organization currently address these types of wastes?
• What information resources, tools or guidance would help your organization address the challenges or barriers you've identified related to waste sampling?
• Is EPA's existing guidance on waste analysis plans and waste sampling ^[1] useful for your organization? Are there any information or data gaps that would improve the usefulness of this guidance? Would it benefit your organization for EPA to update this guidance to include examples or case studies that address the challenges or barriers you've identified?
• What references, other than those published by EPA, does your organization rely on for waste sampling (e.g., standards issued by voluntary consensus standard bodies such as ASTM International, guidance issued by state or local government agencies or other federal agencies, or other policies, regulations or guidance)?

B. TCLP Challenges and Opportunities for Improvement

The Toxicity Characteristic Leaching Procedure (TCLP), SW-846 Method 1311, is used for toxicity characteristic hazardous waste determinations under the characteristic hazardous waste regulations at 40 CFR 261.24 and for compliance with numeric standards for nonwastewaters under the LDR regulations at 40 CFR 268.48. TCLP is designed to simulate leaching under mildly acidic conditions that might exist in an early stage municipal solid waste landfill.

Several technical and practical issues have been raised by the regulated community and others regarding the applicability of the TCLP for identifying hazardous waste. A number of comments were submitted to the Agency in response to the June 13, 1986 proposal to replace the EP with the TCLP. The Agency responded to the comments in the final rule but also decided to further evaluate modifications to the TCLP. The Agency stated that further improvements in the TCLP will be proposed as they are developed. Additional concerns have been raised by commenters during later rulemakings ( e.g., by the SAB and rules addressing newly listed or identified wastes). The identified concerns included:

• TCLP can underestimate leaching of contaminants from some highly alkaline wastes or exposure to alkaline environments.
• TCLP can underestimate leaching of contaminants from oily wastes and some paint wastes.
• TCLP may not accurately mimic conditions commonly found in non-hazardous industrial waste landfills.
• TCLP may underestimate the chelation-facilitated mobility of some waste constituents.
• TCLP does not account for the oxidation/reduction reactions occurring in landfills.
• TCLP may not accurately predict long-term mobility of organic contaminants in some treated wastes.
• TCLP may not be appropriate for some contaminated soils.
• TCLP does not predict releases to non-groundwater pathways.

EPA is requesting information from the public on the current state of TCLP use and of compliance with TCLP numerical standards. Suggested questions to consider for comment submission include:

• What challenges or barriers does your organization face when using Method 1311 for RCRA regulatory compliance testing? ^[2]
• Which types of wastes or waste properties present the biggest challenges for TCLP testing, and why?
• Are there specific process steps in Method 1311 that are particularly challenging or ambiguous?
• What kinds of benefits or costs would your organization experience if EPA updated the method or issued interpretive guidance? For example, the following issues have been raised by previous method users:
  • Method 1311 provides a maximum particle size, but not a minimum particle size.
  • Method 1311 allows vacuum filtration to be used for liquid-solid separations, but the applicability is limited.^[3]
• What additional information resources or tools would be most helpful for your organization to overcome challenges related to TCLP testing?
• Has your organization developed any additional training materials or handbooks to assist in performing Method 1311?

C. Leaching Environmental Assessment Framework (LEAF) as an Alternative to TCLP

The Leaching Environmental Assessment Framework (LEAF) analytical methods ^[4] (SW-846 Methods 1313, 1314, 1315, 1316) developed for inorganics were designed to consider the impact on leaching of waste forms and environmental conditions that are known to affect leaching, and which vary in value for different wastes and disposal conditions. Therefore, LEAF considers the impact on leaching of varying pH of the leachate, varying the liquid-to-solid ratio (or the amount of liquid contacting the waste), and the waste form ( e.g., granular materials such as soils or monolithic solids such as a concrete block). The LEAF tests include equilibrium tests on sieved or particle-size reduced solids (which can identify maximum plausible leaching) but also include dynamic leaching tests to estimate mass transfer rates and provide better estimates of constituent mass release and flux from granular or monolithic solid waste forms. The published LEAF methods have only been validated for inorganic chemicals, and EPA is currently conducting research and development to adapt the ( printed page 58120) leaching methods to address organic constituents as well.

The LEAF methods are intended for situations where an assessment tailored to site conditions is needed where the conditions differ from the disposal scenario addressed by TCLP, and TCLP is not required by RCRA regulations (that is, the waste is not subject to LDR treatment requirements that rely on TCLP or is not RCRA hazardous waste). Uses include delisting, beneficial use assessments, and treatment effectiveness evaluations.

EPA is considering providing a regulatory alternative to TCLP testing for wastes to evaluate leaching of chemicals from wastes disposed in lined landfills other than municipal solid waste landfills.^[5] Alternative aqueous leaching tests such as the LEAF methods could be used to evaluate leaching of regulated chemicals from wastes that considers the physical waste form and the range of conditions to which it would be exposed at a given disposal site, thereby ensuring disposal of the waste is protective of human health and the environment. EPA is still considering options for how best to define the range of conditions to be used for testing, including using measured leachate properties from a specific landfill site, or using leachate properties from landfills of similar types and/or geographic areas.

EPA is requesting information from the public on whether alternative leaching methods would be useful for evaluation of waste leaching under alternative conditions, such as those that exist in landfills other than municipal solid waste landfills regulated under RCRA subtitle D at 40 CFR part 258. Suggested questions to consider for comment submission include:

For Hazardous Waste Generators or Hazardous Waste Treatment, Storage, and Disposal Facilities:

• What alternative leaching tests, if any, does your organization currently use to aid in hazardous waste identification and/or LDR compliance?
• What are the barriers and sources of demand for using LEAF for your organization?
  • Would your organization potentially benefit from having more flexibility to make site-specific evaluations of aqueous leaching from waste for disposal in a landfill other than a municipal solid waste landfill?
  • Does your organization currently produce or manage a toxicity characteristic hazardous waste stream that potentially would not exceed leaching-based RCRA regulatory thresholds under management conditions at a non-MSW landfill?
• What kinds of benefits or costs would your organization experience if EPA made regulatory updates consistent with this approach for waste disposal?
• What impacts would the cost of LEAF testing, relative to TCLP, have on your organization's likelihood of using this regulatory alternative compared to your current waste management practices?

For RCRA Subtitle C authorized States:

• What specific wastes or management situations does your organization encounter that would benefit most from using the LEAF approach?
• What challenges or barriers would your organization have to overcome to adopt RCRA regulatory updates to provide flexibility in complying with RCRA regulatory thresholds currently based on TCLP?
• How much additional cost would your organization incur to implement this regulatory alternative compared to your current practices, and could these additional costs be offset with an additional fee?
• What additional technical support or other resources would your organization need to support this regulatory flexibility?
• Does your organization have any suggestions for how EPA could facilitate state adoption of a more flexible regulatory approach for waste testing such as using the LEAF methods to ensure disposal of wastes will be protective of human health and the environment?
• Does your organization have any suggestions for how to define the range of conditions across which wastes would need to be tested to ensure disposal of wastes will be protective of human health and the environment?

D. Other SW-846 Method Needs, Uses, and Issues

The Methods Innovation Rule (70 FR 34538, June 14, 2005) removed certain required uses of SW-846 methods, and to allow more flexibility in test method selection. The rule allowed laboratories to modify SW-846 methods, provided the modified method meets the defined quality assurance parameters established in the method or defined for the project; and to use non-SW-846 methods, provided the method falls within EPA's parameter to protect human health and the environment. All SW-846 methods were covered by this rule except for methods that involve determination of method-defined parameters (MDPs), such as TCLP, which must be followed to the letter for regulatory compliance.

In 2016, EPA further streamlined the approval process for non-regulatory methods in SW-846 (81 FR 66276, September 27, 2016). Some MDP were updated in the Modernizing Ignitable Liquids Determination Rule (85 FR 40594, July 7, 2020).

EPA is requesting information from the public on MDPs and SW-846 methods including how they are used, testing challenges, and needs for updates and new methods. Suggested questions to consider for comment submission include:

For Hazardous Waste Generators/Treatment, Storage, and Disposal Facilities:

• Which SW-846 methods are the most useful for your organization?
• Which SW-846 methods are most in need of revision due to equipment obsolescence, capacity constraints, quality limitations, or other challenges?
• What are the highest priority gaps in SW-846 methods for identifying hazardous waste characteristics?
• What are the highest priority gaps in SW-846 methods for demonstrating compliance with LDR requirements?
• Which aspects of waste management present the biggest hazardous waste identification challenges for your organization,e.g., waste sampling, testing, transport, treatment, or disposal, and why?
• What additional challenges does your organization have with using current SW-846 methods? For example, what unmet methods-related needs, if any, does your organization have for RCRA regulatory compliance testing?

For RCRA-authorized States:

• What are the biggest uncertainties related to methods that your organization has for assuring compliance with hazardous waste characteristic regulations or compliance with numeric standards for treated hazardous wastes?
• What challenges does your organization have with using current SW-846 methods?
• What unmet methods-related needs does your organization have related to RCRA regulatory compliance?
• What opportunities and challenges does your organization face with adopting updated methods?

V. Disclaimer and Important Note

This RFI is issued solely for information, research and planning purposes and does not constitute a Request for Proposals (RFP) or a Request ( printed page 58121) for Applications (RFA). Any information obtained as a result of this RFI is intended to be used by EPA on a non-attribution basis to support EPA's efforts to evaluate potential updates to SW-846 Methods, including Methods 1311 (TCLP), 1313-1316 (LEAF), and Waste Sampling Guidance. This RFI does not constitute a formal solicitation for proposals or abstracts. Your response to this document will be treated as information only. This RFI does not represent any award commitment on the part of EPA, nor does it obligate EPA to pay for costs incurred in the preparation and submission of any responses.

91 FR 58117