Hazardous and Solid Waste Management System: Disposal of Coal Combustion Residuals From Electric Utilities; Legacy/CCRMU Amendments

Federal RegisterApr 13, 2026

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 257

[EPA-HQ-OLEM-2020-0107; FRL-7814.3-01-OLEM]

RIN 2050-AH39

Hazardous and Solid Waste Management System: Disposal of Coal Combustion Residuals From Electric Utilities; Legacy/CCRMU Amendments

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule; public hearing.

SUMMARY:

The Environmental Protection Agency (EPA or the Agency) is proposing several revisions to the existing federal CCR regulations, including exempting CCR dewatering structures and modifying the legacy coal combustion residual (CCR) surface impoundment and CCR management unit provisions. Additionally, EPA is proposing to establish a new compliance pathway that allows for site-specific considerations during permitting regarding the groundwater monitoring points of compliance, the cleanup levels for corrective action, the appropriate closure requirements, closure timeframes, and allowing CCR extraction for beneficial use during the post-closure care period. The Agency is also proposing to revise the definition of beneficial use by eliminating the requirement for an environmental demonstration for the non-roadway use of more than 12,400 tons of unencapsulated CCR on land, as well as proposing a definition of CCR storage pile, and proposing to exclude specific beneficial uses from federal CCR regulations. Lastly, EPA is providing notice that EPA will reopen the public comment period for the Federal CCR permit program proposed rule, published on February 20, 2020, for a period of 30 days in a future separate action.

DATES:

Comments due:

Comments on this action must be received on or before June 12, 2026.

Public hearing:

EPA will hold an online (

i.e.,

virtual) public hearing on May 28, 2026. Please refer to the

SUPPLEMENTARY INFORMATION

section for additional information on the public hearing.

ADDRESSES:

You may send comments on this action, identified by Docket ID No. EPA-HQ-OLEM-2020-0107, by any of the following methods:

•

Federal eRulemaking Portal: https://www.regulations.gov/

(our preferred method). Follow the online instructions for submitting comments. A plain language summary of the proposed rule is also available on the Federal eRulemaking Portal.

•

Mail:

U.S. Environmental Protection Agency, EPA Docket Center, Office of Land and Emergency Management (OLEM) Docket, Mail Code 28221T, 1200 Pennsylvania Ave. NW, Washington, DC 20460.

•

Hand Delivery or Courier

(by scheduled appointment only):

EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. The Docket Center's hours of operations are 8:30 a.m.-4:30 p.m., Monday-Friday (except Federal Holidays).

Instructions:

All submissions received must include the Docket ID No. for this rulemaking. Comments received may be posted without change to

https://www.regulations.gov/,

including any personal information provided. For detailed instructions on sending comments and additional information on the rulemaking process, see the “Public Participation” heading of the

SUPPLEMENTARY INFORMATION

section of this document.

The public hearing will be held online (

i.e.,

virtually). Refer to the

SUPPLEMENTARY INFORMATION

section below for additional information.

FOR FURTHER INFORMATION CONTACT:

Taylor Holt, Office of Resource Conservation and Recovery, Waste Identification, Notice, and Generators Division, Environmental Protection Agency, 1200 Pennsylvania Avenue NW, MC: 5304T, Washington, DC 20460; telephone number: (202) 566-1439; email address:

holt.taylor@epa.gov.

For questions concerning the beneficial use provisions discussed in Unit IV.C. of this preamble, contact Tracy Atagi, Office of Resource Conservation and Recovery, Waste Identification, Notice, and Generators Division, Environmental Protection Agency, 1200 Pennsylvania Avenue NW, MC: 5304T, Washington, DC 20460; telephone number: (202) 566-0511; email address:

atagi.tracy@epa.gov.

For more information on this rulemaking please visit

https://www.epa.gov/coal-combustion-residuals.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Public Participation

A. Written Comments

B. Participation in the Hybrid In-Person and Virtual Public Hearing

II. General Information

A. Does this action apply to me?

B. What action is the agency contemplating?

C. What is the agency's authority for taking this action?

D. What are the incremental costs and benefits of this action?

III. Background

A. 2015 CCR Rule

B. 2023 Legacy Proposed Rule

C. 2024 Legacy Final Rule

D. New Information Received Since Publication of the Legacy Final Rule

E. Beneficial Use of CCR

1. May 2000 Regulatory Determination on Fossil Fuel Combustion Wastes

2. Beneficial Use in the 2015 CCR Rule

3. CCR Rule Litigation Related to Beneficial Use

4. Beneficial Use in the 2019 CCR Proposed Rule

5. 2020 CCR Notice of Data Availability

6. Public Comments on the Fourth Beneficial Use Criterion and CCR Accumulations for the 2019 CCR Proposal and 2020 CCR NODA and EPA's Decision To Repropose

IV. What is EPA proposing?

A. Amendments to the Self-Implementing Regulations

1. CCR Dewatering Structures

2. Legacy CCR Surface Impoundments

3. CCR Management Units

4. Initial Timeframes for Background Sampling for New CCR Landfills, CCR Surface Impoundments, and Any Lateral Expansions

5. Slope Stability Requirements for Vegetation

B. New Compliance Pathway Allowing Site-Specific Considerations During Permitting

1. Groundwater Monitoring and Corrective Action Requirements

2. Closure and Post-Closure Care Requirements

C. Beneficial Use

1. Definition of Beneficial Use

2. Revisions Related to CCR Accumulations

3. Exclusions for Specific Beneficial Uses

D. Federal CCR Permitting Rule—Reopening the Comment Period

V. The Projected Economic Impact of This Action

A. Introduction

B. Affected Universe

C. Baseline Costs

D. Costs and Benefits of the Proposed Rule

E. What analysis of children's health did we conduct?

VI. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review

B. Executive Order 14192: Unleashing Prosperity Through Deregulation

C. Paperwork Reduction Act (PRA)

D. Regulatory Flexibility Act (RFA)

E. Unfunded Mandates Reform Act (UMRA)

F. Executive Order 13132: Federalism

G. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments

H. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks

I. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution or Use

J. National Technology Transfer and Advancement Act (NTTAA)

List of Acronyms

ACAA American Coal Ash Association

AEP American Electric Power

ARAR Applicable or Relevant and Appropriate Requirement

BH Berkshire Hathaway

CAMA Coal Ash Management Act

CARA Corrective Action/Risk Assessment

CBI Confidential Business Information

CCIG Cross-Cutting Issues Group

CCR coal combustion residuals

CCRMU coal combustion residuals management unit

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CFR Code of Federal Regulations

CSM Conceptual Site Model

EEI Edison Electric Institute

EPA Environmental Protection Agency

F.A.C. Florida Administrative Code

FER facility evaluation report

Federal Register

HELP Hydrologic Evaluation of Landfill Performance

HSWA Hazardous and Solid Waste Amendments

ICR Information Collection Request

IEPA Illinois Environmental Protection Agency

LEAF Leaching Environmental Assessment Framework

MCL maximum contaminant level

MSWLF Municipal Solid Waste Landfill

NAICS North American Industry Classification System

NCDEQ North Carolina Department of Environmental Quality

N.C.G.S. General Statutes of North Carolina

NPDES National Pollution Discharge Elimination System

NRECA National Rural Electric Cooperative Association

NTTAA National Technology Transfer and Advancement Act

OMB Office of Management and Budget

PRA Paperwork Reduction Act

RCRA Resource Conservation and Recovery Act

RIA Regulatory Impact Analysis

SCDHEC South Department of Health and Environmental Control

TDEC Tennessee Department of Environment and Conservation

TVA Tennessee Valley Authority

USWAG Utility Solid Waste Activities Group

UV Ultraviolet

WIIN Water Infrastructure Improvements for the Nation

I. Public Participation

A. Written Comments

Submit your comments on this action, identified by Docket ID No. EPA-HQ-OLEM-2020-0107, at

https://www.regulations.gov

(our preferred method), or the other methods identified in the

ADDRESSES

section. Do not submit any comments on the Federal CCR permit program proposed rule to this docket; comments on that action must be submitted during the reopened comment period to Docket ID No. EPA-HQ-OLEM-2019-0361 in accordance with the future

Federal Register

document. Once submitted, comments cannot be edited or removed from the docket. EPA may publish any comment received to its public docket. Do not submit to EPA's docket at

https://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. 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

https://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.

B. Participation in the Virtual Public Hearing

EPA will hold a virtual public hearing on May 28, 2026. The hearing will convene at 9:00 a.m. Eastern time (ET) and will conclude at 6:00 p.m. (ET).

EPA will begin pre-registering speakers for the hearing upon publication of this document in the

Federal Register

. To register to speak at the hearing, please use the online registration form available on EPA's CCR website (

https://www.epa.gov/coal-combustion-residuals

) or contact the person listed in the

FOR FURTHER INFORMATION CONTACT

section to register to speak at the hybrid hearing. The last day to pre-register to speak at the hearing will be May 26, 2026. On May 26, 2026, EPA will post a general agenda for the hearing on EPA's CCR website (

https://www.epa.gov/coal-combustion-residuals

EPA will make every effort to follow the schedule as closely as possible on the day of the hearing; however, please plan for the hearings to run either ahead of schedule or behind schedule. Additionally, requests to speak will be taken the day of the hearing according to the procedures specified on EPA's CCR website (

https://www.epa.gov/coal-combustion-residuals

) for this hearing. EPA will make every effort to accommodate all speakers who register or join virtually, although preferences on speaking times may not be able to be fulfilled.

Each commenter will have five (5) minutes to provide oral testimony. EPA encourages commenters to provide EPA with a copy of their oral testimony electronically by emailing it to the person listed in the

FOR FURTHER INFORMATION CONTACT

section. EPA also recommends submitting the text of your oral comments as written comments to the rulemaking docket. If EPA is anticipating a high attendance, the time allotment per testimony may be shortened to no less than three (3) minutes per person to accommodate all those wishing to provide testimony and who have pre-registered. While EPA will make every effort to accommodate all speakers who do not preregister, opportunities to speak may be limited based upon the number of pre-registered speakers. Therefore, EPA strongly encourages anyone wishing to speak to preregister. Participation in the public hearing does not preclude any entity or individual from submitting a written comment.

EPA may ask clarifying questions during the oral presentations but will not respond to the presentations at that time. Written statements and supporting information submitted during the comment period will be considered with the same weight as oral comments and supporting information presented at the public hearing. Verbatim transcripts of the hearings and written statements will be included in the docket for the rulemaking.

Please note that any updates made to any aspect of the hearing will be posted online at EPA's CCR website at

https://www.epa.gov/coal-combustion-residuals.

While EPA expects the hearing to go forward as set forth above, please monitor our website or contact the person listed in the

FOR FURTHER INFORMATION CONTACT

section to determine if there are any updates. EPA does not intend to publish a document in the

Federal Register

announcing updates.

If you require the services of an interpreter, translator, or special accommodations such as audio transcription or closed captioning, please pre-register for the hearing with the person listed in the

FOR FURTHER INFORMATION CONTACT

section and describe your needs by May 14, 2026. EPA may not be able to arrange accommodations without advance notice. Registrants should notify the person listed in the

FOR FURTHER INFORMATION CONTACT

section and

indicate on the registration form any such needs when they pre-register to speak.

II. General Information

A. Does this action apply to me?

This rule may be of interest to electric utilities and independent power producers that fall within the North American Industry Classification System (NAICS) code 221112. The reference to NAICS code 221112 is not intended to be exhaustive but rather provides a guide for readers regarding entities likely to be affected by this action. This discussion lists the types of entities that EPA is now aware could potentially be affected by this action. Other types of entities not described here could also be affected. To determine whether your entity is affected by this action, you should carefully examine the applicability criteria found in § 257.50 of title 40 of the Code of Federal Regulations (CFR). If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the

FOR FURTHER INFORMATION CONTACT

section.

B. What action is the agency contemplating?

EPA is proposing to amend the regulations governing the disposal of CCR in landfills and surface impoundments and defining the beneficial use of CCR, codified in 40 CFR part 257, subpart D (CCR regulations). First, the Agency is proposing to exempt CCR dewatering structures from the CCR regulations under part 257 and to establish a new compliance pathway that allows for site-specific considerations during permitting. This pathway incorporates permit flexibilities for CCR units complying with the federal CCR groundwater monitoring, corrective action, and closure requirements under a federal or participating-state CCR permit. Additionally, EPA is proposing to clarify the deadline by which new CCR landfills and CCR surface impoundments (which includes any lateral expansions) must comply with the requirement to establish background concentrations.

EPA is also proposing to amend the regulations governing the disposal of CCR in CCR surface impoundments that no longer receive CCR but contained both CCR and liquids on or after October 19, 2015 and are located at inactive facilities (

i.e.,

legacy CCR surface impounds) and the regulations governing the disposal of CCR in inactive and closed landfills, in closed surface impoundments and on land where noncontainerized accumulations of CCR are received, placed, or otherwise managed (

i.e.,

CCR management units or CCRMU). Specifically, the Agency is proposing to: (1) Broaden the criteria for the closure by removal certification for legacy CCR surface impoundments; (2) Broaden the deferral criteria for legacy CCR surface impoundments that have completed closure under a regulatory authority prior to November 8, 2024; and (3) Amend the scope of the CCRMU regulations.

Furthermore, EPA is proposing to revise several provisions related to CCR beneficial use. Specifically, the Agency is proposing to revise the definition of beneficial use by removing the fourth criterion that requires an environmental demonstration for the non-roadway use of more than 12,400 tons of unencapsulated CCR on land, proposing a definition of CCR storage pile, and excluding the following beneficial uses from federal CCR regulations: (1) CCR used in cement manufacturing at cement kilns, (2) Flue gas desulfurization (FGD) gypsum used in agriculture, and (3) FGD gypsum used in wallboard.

Lastly, EPA is providing notice that in a future separate action identified by Docket ID No. EPA-HQ-OLEM-2019-0361, EPA will reopen the public comment period for the Federal CCR permit program proposed rule (85 FR 9940, entitled

Hazardous and Solid Waste Management System: Disposal of Coal Combustion Residuals From Electric Utilities; Federal CCR Permit Program

) for a period of 30 days. Note that comments on the Federal CCR permit program proposed rule must be submitted to Docket ID No. EPA-HQ-OLEM-2019-0361 during the future reopening of the comment period to be considered.

EPA intends that the provisions of the rule be severable. In the event that any individual provision or part of the rule is invalidated, EPA intends that this would not render the entire rule invalid, and that any individual provisions that can continue to operate will be left in place.

In this proposal, EPA is not reconsidering, proposing to reopen, or otherwise soliciting comment on any other provisions of the existing CCR regulations beyond those specifically identified in this proposal. For the reader's convenience, EPA has provided a background description of existing requirements in several places throughout this preamble. In the absence of a specific request for comment or proposed change to the identified provisions, these descriptions do not reopen any of the described provisions. EPA will not respond to comments submitted on any issues other than those specifically identified in this proposal, and such comments will not be considered part of the rulemaking record.

C. What is the agency's authority for taking this action?

EPA is publishing this rulemaking under the authority of sections 1008(a)(3), 2002(a), 4004, and 4005(a), (d) of the Solid Waste Disposal Act of 1965, as amended by the Resource Conservation and Recovery Act of 1976 (RCRA), as amended by the Hazardous and Solid Waste Amendments of 1984 (HSWA) and the Water Infrastructure Improvements for the Nation (WIIN) Act of 2016, 42 U.S.C. 6907(a), 6912(a), 6944, 6945(a) and (d).

D. What are the incremental costs and benefits of this action?

EPA establishes the requirements under RCRA sections 1008(a)(3) and 4004(a) without taking cost into account. See,

Utility Solid Waste Activities Group, et al.

EPA

(

USWAG

) 901 F.3d 414, 448-49 (D.C. Cir. 2018). The following cost estimates are presented in the Regulatory Impact Analysis (RIA) and summarized in this preamble for compliance with OMB Circular A-4 and E.O. 12866. The requirements in this rule do not rely on these cost estimates.

The RIA estimates that the annualized cost savings of this action will be approximately:

• $174-$194 million per year when discounting at 3%; and

• $232-$262 million per year when discounting at 7%.

The RIA estimates that the annualized change in benefits of this action will be approximately:

• A $5 million decrease per year when discounting at 3%; and

• A $4-$2 million decrease when discounting at 7%.

Overall, the RIA estimates that the net annualized cost savings and benefits, net of disbenefits, of this action will be $169-$189 million per year when discounting at 3%, and $229-$260 million when discounting at 7%.

Further information on the economic effects of this action can be found in Unit VII. of this preamble.

III. Background

A. 2015 CCR Rule

On April 17, 2015, EPA finalized national minimum criteria for the disposal of CCR as solid waste under

subtitle D of RCRA titled, “Hazardous and Solid Waste Management System; Disposal of Coal Combustion Residuals from Electric Utilities” (80 FR 21302) (2015 CCR Rule). The 2015 CCR Rule, codified in subpart D of part 257 of title 40 of the CFR, established regulations for existing and new CCR landfills, existing and new CCR surface impoundments, including all lateral expansions of these CCR units. The 2015 CCR Rule also imposed requirements on inactive surface impoundments at active facilities but exempted inactive surface impoundments at inactive facilities. The requirements consist of location restrictions, design and operating criteria, groundwater monitoring and corrective action requirements, closure and post-closure care requirements, recordkeeping, notification, and website posting requirements.

At the time of the promulgation of the 2015 CCR Rule, EPA did not have the authority to issue CCR permits, authorize state CCR permit programs, or otherwise provide the oversight typically performed by a regulatory agency or permit authority. Therefore, the 2015 CCR Rule established nationwide requirements for CCR units under a self-implementing regulatory structure. Due to the lack of regulatory oversight and the limitations of a national risk assessment, as described in Unit III.D. below, the 2015 CCR Rule did not allow for site-specific variances from the regulations or tailored requirements based on site-specific characteristics. Instead, the 2015 CCR Rule relied on certifications by qualified professional engineers and web posting requirements as a substitute for regulatory oversight in certain cases.

As discussed in Unit IV.B. of this preamble, the self-implementing framework and national requirements have resulted in a one-size-fits-all approach to compliance with the federal CCR requirements. For example, site-specific revisions to the technical standards are not permissible under the 2015 CCR Rule due to the lack of regulatory oversight. Likewise, as discussed in Unit III.B.1.b. of this preamble, during the development of the 2015 Rule, EPA rejected requests to allow regulated entities to establish alternative groundwater standards for constituents without a federal maximum contaminant level (MCL) established under §§ 141.62 and 141.66 and referenced in § 257.95(h)(1) due to a lack of regulatory oversight and scientific expertise. Consequently, the 2015 CCR Rule represents a regulatory structure that met the RCRA standard of no reasonable probability of adverse effect to health or the environment within the constraints of the law at that time. However, as discussed in further detail in Units III.D. and IV.B. of this preamble, the self-implementing framework is no longer the only, nor the best, regulatory structure available.

B. 2023 Legacy Proposed Rule

On May 18, 2023, EPA proposed revisions to the CCR regulations (88 FR 31982) (“the Legacy Proposed Rule” or “Legacy Proposal”). These revisions included establishing regulations specifying that legacy CCR surface impoundments are subject to 40 CFR part 257, subpart D and that owners or operators of legacy CCR surface impoundments must comply with all the appropriate requirements applicable to inactive CCR surface impoundments at active facilities. In addition, EPA proposed to establish requirements to address the risks from certain exempt solid waste management that involves the direct placement of CCR on the land (

i.e.,

CCRMU). EPA proposed to extend a subset of the existing requirements in part 257, subpart D to CCRMU, which was proposed to include CCR surface impoundments and landfills that closed prior to the effective date of the 2015 CCR Rule, inactive CCR landfills, and other areas where CCR is managed directly on the land. EPA proposed to apply the CCRMU provisions to all active CCR facilities and all inactive facilities with a legacy CCR surface impoundment.

C. 2024 Legacy Final Rule

On May 8, 2024, EPA established regulations applicable to inactive surface impoundments at inactive facilities (legacy CCR surface impoundments or legacy impoundments) under 40 CFR part 257, subpart D (89 FR 38950) (Legacy Final Rule). EPA also established regulations requiring owners and operators of legacy CCR surface impoundments to comply with the following requirements in the existing CCR regulations: installation of a permanent marker, history of construction, hazard potential classification, structural stability and factors of safety assessments, emergency action plan, air criteria, inspections, groundwater monitoring and corrective action, closure and post-closure care, recordkeeping, and notification and CCR website requirements. EPA further established new compliance deadlines for these newly applicable regulatory requirements to ensure the owners or operators of these units have time to come into compliance.

In addition, the Legacy Final Rule established requirements to address the risks from solid waste management activities that involves the direct placement of CCR on the land. EPA extended a subset of the existing requirements in 40 CFR part 257, subpart D to CCRMU, which are CCR surface impoundments and landfills that closed prior to the effective date of the 2015 CCR Rule, inactive CCR landfills, and other areas where CCR is managed directly on the land. These additional requirements apply to all active CCR facilities, all inactive facilities with legacy CCR surface impoundments, and those active facilities (

i.e.,

facilities producing electricity for the grid as of October 19, 2015) that ceased placing CCR in onsite CCR units prior to the effective date of the 2015 CCR Rule.

Owners or operators of some legacy CCR surface impoundments and CCRMU that had closed under a regulatory authority are eligible for certain relief from the established regulatory requirements provided they met specific criteria. Owners or operator of legacy CCR surface impoundments who certify that prior to November 8, 2024, they completed closure by removal of the impoundment, consistent with the standards in § 257.102(c), are subject to no further requirements under the Legacy Final Rule for that unit. Similarly, for legacy CCR surface impoundments and CCRMU that completed a closure prior to November 8, 2024, and can meet the criteria in § 257.101(g), compliance with the closure criteria in § 257.102 is deferred until a permitting authority can evaluate the previous closure to determine if it met the appropriate section of the § 257.102 closure standard. Owners or operators of these units are still required to comply with rest of the applicable CCR regulations.

Owners or operators of an active facility or a facility with a legacy CCR surface impoundment are required to conduct a facility evaluation to identify and delineate any CCRMU at the facility and document the findings in two reports, FER Part 1 and FER Part 2. See § 257.75(b). The FER Part 1 documents the thorough review of readily and reasonably available records regarding where CCR was either routinely and systematically placed on land, or where facility activities otherwise resulted in measurable accumulations of CCR on land. The FER Part 2 documents the conclusions of a physical evaluation of the facility to address any data and information gaps identified in FER Part 1. Together, the FER Parts 1 and 2 give a complete picture of the historic use, placement and the status of CCR at the facility, ultimately identifying any

CCRMU of 1 ton or greater onsite. After identifying the regulated CCRMU through the facility evaluation, owners or operators of CCRMU must comply with the existing requirements in 40 CFR part 257, subpart D for groundwater monitoring, corrective action (where necessary), and in certain cases, closure, and post-closure care requirements.

D. New Information Received Since Publication of the Legacy Final Rule

Several of these letters and materials critiqued the findings or applicability of the 2014 and 2024 Risk Assessments conducted by EPA to support the 2015 CCR Rule and the Legacy Final Rule, respectively. Most recently, EPA received two reports that critique the Agency's Risk Assessments, which were prepared on behalf of various industry groups.

2 3

These materials are available in the docket for this rulemaking.

Haley Aldrich. 2025. “Report on Joint Data Analysis to Support Revisions to Federal Regulation of Coal Combustion Residuals.” Prepared for American Electric Power, Duke Energy Corporation, Southern Company Services Inc., and Vistra Corp., Greenville, SC. September.

Gradient. 2025. “Technical Evaluation of the Environmental Protection Agency's 2024 Risk Assessment of CCR Management Units.” Prepared for Utility Solid Waste Activities Group and National Rural Electric Cooperative Association. Boston, MA. November.

Throughout the rulemaking process and thereafter, EPA has received comments from industry groups and individual companies criticizing both the 2014 and 2024 Risk Assessments as overly conservative. These comments frequently reference some combination of literature and field data to assert the risks posed by individual units are not as high as those reported in the two risk assessments. The Agency has previously addressed various iterations of these types of comments in the preamble discussions and response to comments documents for both the 2015 CCR Rule and the Legacy Final Rule, and so does not replicate those specific responses here. Instead, the following discussion focuses on the broader theme of these comments, which is that not every CCR unit will pose the same level of risk.

The “Report on Joint Data Analysis” states that it draws on site-specific data from 38 CCR landfills, surface impoundments and CCR management unit fills at 19 stations across nine states. This report summarizes unit characteristics and groundwater monitoring data, along with data drawn from broader literature, and compared those data against values modeled in the Risk Assessments. The other report, “Technical Evaluation,” summarizes a separate effort to re-evaluate the modeling approach for CCRMU fills. This effort involved varying different model inputs used in the screening phase of the 2024 Risk Assessment and evaluating how that altered those initial risk results. Both reports conclude that EPA's Risk Assessments systematically overstate the risk from CCR disposal units and fills, and that it would be more effective and appropriate to assess risks on a site-specific basis. For example, the “Technical Evaluation” emphasized that individual fills are generally smaller than the disposal units regulated in 2015. The 2024 Risk Assessment demonstrated that risks tend to decrease along with size due to the smaller volumes of leachate generated. The fills associated with high-end risks that formed the basis for national regulation tend to be on the larger end of the size spectrum. However, there remains a sizeable fraction of modeled scenarios where smaller units were found to result in no adverse impacts to groundwater quality. EPA has acknowledged there is a lack of data from facilities about the actual distribution of fill sizes across the country. As such, there is potential that the prevalence of these smaller fills were underrepresented in previous modeling.

The 2014 and 2024 Risk Assessments aimed to incorporate the best available data at the time of each assessment. Site-specific data were used where available, supplemented by regional and national data to fill data gaps, to capture the variability of waste management practices, environmental conditions, and receptor behavior. However, it is inevitable that some sources of uncertainty and variability will remain in any risk assessment. To account for this fact, EPA typically considers a “high-end” exposure level to ensure an adequate margin of safety for most of the potentially exposed, susceptible population, or ecosystem. EPA's high-end levels typically fall around the 90th percentile and above, an approach designed to be consistent with both legislative mandates and recommendations from the National Academy of Sciences' National Research Council.

U.S. EPA. 2004. “An Examination of EPA Risk Assessment Principles and Practices.” EPA/100/B-04/00. Prepared by the Office of the Science Advisor. Washington, DC. March.

EPA uses a national risk assessment for a particular source or industry category to inform its decision concerning whether a regulatory program is needed or in need of revisions. Both the 2014 and 2024 Risk Assessments were designed to capture the full spectrum of potential disposal scenarios across the country with available data. Decisions about the need for national regulations were based on high-end risks identified from across these scenarios, considered together with damage cases, to ensure that regulations would be consistently protective. Consequently, the 2014 Risk Assessment has served its purpose as EPA used it to inform its decision to create the 2015 CCR Rule creating a Federal CCR regulatory program. EPA relied on the 2024 Risk Assessment to inform its decision to expand the Federal CCR regulations to cover CCRMU.

The Agency acknowledges that these high-end risks may not manifest at every site and concurs that risks associated with individual CCR units may be lower. This is equally true for disposal units, fills, piles, and unencapsulated accumulations on the land for any other stated purpose. However, pinpointing conditions that would lead to reliably lower risks and justify less stringent national standards is complicated by limited site characterization and various factors that could not be reliably modeled at a national level, such as waste disposed below the water table. While this diversity of site conditions creates uncertainty in a national model, it provides a key rationale for the need to design a regulatory program that can account for these site-specific conditions while providing for sufficient regulatory oversight.

Owners or operators of regulated facilities have installed groundwater monitoring networks downgradient of regulated disposal units. Whether prior to or since promulgation of the 2015 CCR Rule, these systems are designed to demonstrate whether a release has occurred. If a release is detected, additional information about the magnitude and extent of the release from the unit and the potential for contamination to spread is required to design a remedial system. That type of broader site characterization typically occurs as part of remedy selection, which most sites have either not yet triggered or completed. Consequently, while industry comments providing further information may lack the types or resolution of data needed to

meaningfully update the existing national risk assessments, the submitted data and description of regulatory oversight provide a foundation for revisions to the self-implementing 2015 CCR Rule to add an option for site-specific determinations involving a permitting authority. A number of commenters cited to data drawn from the broader literature, rather than site-specific measurements. While national data is helpful, any further refinement of the existing risk record will likely need to rely on data from individual sites, where more representative data can be reliably compiled.

To address identified risks in the 2014 Risk Assessment, EPA promulgated national requirements under the authorities in sections 1008(a), 4004, and 4005(a) of RCRA. This included detailed, prescriptive requirements for design of groundwater monitoring systems and corrective action programs drawn from the existing 40 CFR parts 264 and 258 regulations. Decades of experience implementing these requirements for a variety of other wastes, under a range of conditions, provided the Agency confidence that similar performance standards would be equally protective for CCR disposal. When EPA later expanded the regulated universe as part of the Legacy Final Rule to include legacy surface impoundments and CCRMU, the Agency promulgated requirements intended to provide comparable standards across the regulated universe.

During these rulemakings, EPA received numerous comments requesting that EPA adopt alternative performance standards that would allow a permit authority, such as a state regulator (or owners or operators of facilities) to “tailor” the requirements to particular site conditions. Many requested EPA adopt particular performance standards found in EPA's municipal solid waste landfill (MSWLF) regulations in 40 CFR part 258.

Although the 2015 CCR Rule was largely modeled on the MSWLF regulations, as explained in both the proposed and final rules, at the time EPA lacked the authority to establish a program analogous to part 258, which relies on approved states to implement the federal criteria through a permitting program. In addition, in 2015, EPA could not issue permits or enforce any of the CCR regulations. In the absence of a mandated oversight mechanism to ensure that the alternative standards would be technically appropriate, EPA concluded it could not adopt many of the “more flexible” performance standards that commenters requested. Many of these provisions are not tied to specific performance standards that could be used to readily judge compliance. EPA concluded that allowing individual owners and operators to interpret and implement these provisions in the absence of any mandated oversight mechanism would create too much potential for misinterpretation. Instead, the 2015 CCR Rule was designed to be self-implementing, tied to concrete performance and design standards that must be met, so that the rule could be implemented and compliance demonstrated without any interaction with state or federal regulatory officials.

However, in 2016, the WIIN Act was enacted, establishing new statutory provisions applicable to CCR units, including: (a) Authorizing States to implement the CCR regulations through an EPA-approved permit program; and (b) Authorizing EPA to enforce the regulations and, in certain situations, to serve as the permit authority. In doing so, this legislation provides an opportunity to move away from the “one-size-fits-all” regulatory approach necessitated by the previous statutory structure.

EPA therefore proposes to create an additional regulatory pathway that incorporates new regulatory provisions providing permit authorities the ability to approve certain flexibilities for owners or operators complying with the federal CCR rules under a federal or participating-state CCR permit. The aim of these revisions is to allow a permit authority to establish permit conditions that are better tailored to site conditions. Typically permit authorities can require collection of any additional site data necessary to establish permit conditions, and consequently can develop a better understanding of individual sites than could be achieved in national risk assessments. A refined risk record developed through the permitting process would supersede the previous national assessments. As discussed above, the 2015 CCR Rule was based on high-end risks from across the country, which incorporated regional or national data where site-specific data was unavailable. Consequently, it is expected that a permit authority may determine a set of technical requirements different than those set forth in the national, self-implementing scheme that will achieve the standard of “no reasonable probability of adverse effects on health or the environment” and better account for the site-specific data and risks of individual units and sites. Most provisions discussed throughout this proposal will allow these permit authorities to provide greater flexibility to owners or operators while ensuring there is no reasonable probability of adverse effects on health or the environment from the regulated units.

This is especially relevant to D.C. Circuit caselaw preserving EPA's discretion, when supported by evidence in the record, to classify disposal facilities, set standards for disposal, and structure closure proceedings. In

Utility Solid Waste Activities Group

EPA,

901 F.3d 414, 425 (D.C. Cir. 2018) (“

USWAG”

), the U.S. Court of Appeals for the D.C. Circuit vacated several provisions of the 2015 CCR rule that authorized the continued operation of unlined and clay-lined impoundments and that exempted legacy CCR surface impoundments, finding portions of the 2015 CCR rule to be promulgated without an adequate record to demonstrate regulatory compliance with RCRA. In particular, the court found it “inadequate under RCRA for the EPA to conclude that a major category of impoundments [(

i.e.,

unlined surface impoundments)] that the agency's own data show are prone to leak pose `no reasonable probability of adverse effects on health or the environment . . . simply because they do not already leak.”

Id.

at 427. In addition, the court determined that EPA failed to “explain how the [2015 CCR] Rule's contemplated detection and response could assure `no reasonable probability of adverse effects to health and the environment' at unlined [surface] impoundments,” as well as at “existing impoundments lined with nothing more than compacted soil [

i.e.,

clay-lined surface impoundments].”

Id.

at 431. Similarly, the court found that EPA lacked sufficient rationale to support exempting legacy CCR surface impoundments from the 2015 CCR Rule.

See id.

at 432. Overall, the court's focus on the Agency's lack of rationale to support the vacated portions of 2015 CCR Rule does not preclude future changes to EPA's Part 257 regulations.

Of particular note, while not relevant to the court's determination that portions of the 2015 CCR Rule were arbitrary and capricious, the court recognized that the WIIN Act provides EPA with “new tools[,]”

Id.

at 437, to address CCR. Most notably, the Administrator may approve qualified state permit programs or other systems of prior approval and conditions under State law—for regulation by the State of CCR units—to operate in lieu of EPA regulation of CCR units in the State.

See

42 U.S.C. 6945(d)(1)(B) (d)(3). This broad discretion for the Administrator to approve state permit programs contemplates various standards for what triggers closure, what constitutes

adequate protection of the environment, and the sequencing and timeliness of closure procedures based upon a holistic review of environmental concerns.

As stated elsewhere, the WIIN Act, 42 U.S.C. 6945(d), enhances such flexibility as long as any state permit program or other system of prior State approval is in full compliance with the EPA's Part 257, or successor regulations establishing criteria, governing CCR units. 42 U.S.C. 6945(d)(6). This flexibility is unchallenged by the

USWAG

decision as long as, as stated by the court, EPA's regulatory standard for disposal of solid waste “ensure[s] that there is no reasonable probability of adverse effects on health or the environment.” See

USWAG,

901 F.3d at 448-49 (“RCRA's statutory language instructs the EPA to classify a disposal site as a sanitary landfill and not an open dump only `if there is no reasonable probability of adverse effects on health or the environment from disposal of solid waste at such facility.' (emphasis omitted)); see also

Id.

at 437 (“[A]lthough the WIIN Act does not affect the validity of the Rule itself, it does provide the EPA with new tools to pursue its regulatory goals”).

Thus,

USWAG

is best understood as rejecting the record at issue in that case as insufficient to defend the standards promulgated. This leaves intact a permitting regime which, buttressed by an adequate demonstration that the “no reasonable probability” standard would be met, could still account for site-specific variability. The record established here and through comments to this proposal may support defining an acceptable level of leakage on a unit- or site-specific basis. Such case-by-case analysis may enable each regulatory authority to opt not to close facilities immediately upon monitoring revealing risks but rather enable owners or operators to flexibly comply with an ongoing monitoring regime which guarantees safety. This discretion is cabined by statute and by the court in

USWAG

in that the Administrator may only approve a state alternative permit program if its standards are at least as protective as the criteria set by the EPA in its corresponding (and successor) regulations. See 42 U.S.C. 6945(d)(1)(C); 40 CFR part 257, subpart D.

USWAG

the Court found that EPA had not adequately demonstrated that certain parts of the 2015 regulations adequately met the statutory protectiveness standard in RCRA 4004(a). However, that decision was based on the record EPA used to support its 2015 CCR rule, which was before the court at the time, and

USWAG

does not foreclose further evaluation and consideration of risk in regulating in this area. See,

e.g., USWAG,

901 F.3d at 429 (“EPA has not shown that harmful leaks will be promptly detected; that, once detected, they will be promptly stopped; or that contamination, once it occurs, can be remedied.”) Left intact is the interpretation of section 4004(a) as requiring a baseline standard of protection,

but not uniformity in the manner of attainment,

and EPA maintains broad discretion to adopt performance-based criteria based on a record of protectiveness in various state instances. The

USWAG

court merely found that the record then at issue did not explain how the specific groundwater monitoring and corrective actions proposed were sufficient to mitigate the risks proscribed by statute.

In keeping with

USWAG'

s admonition of the insufficient evidence and analysis behind the 2015 CCR Rule, EPA is seeking additional comment and record support regarding the use of evidence-based engineering controls, institutional controls, risk assessments, hydrogeological assessments and monitoring techniques.

Additionally, EPA solicits comment and data regarding alternative closure timelines which holistically consider the harms posed to the environment by standards of closure which may fail to account for site-specific factors. The

USWAG

decision does not foreclose the Agency from designing an alternative regulatory path that defines the circumstances that would “trigger” a case-by-case, site-specific analysis or one that sets a new identifiable standard to guide the Agency or a permitting authority's judgment when operating under that path.

RCRA requires EPA to set minimum criteria for sanitary landfills that prevent harm to either “health or the environment.” 42 U.S.C. 6944(a). Thus, commenters should focus on the circumstances that should “trigger” a case-by-case analysis and identify the case-specific scenarios necessitating unique regulatory treatment. EPA's discretion to incorporate such judgments into the general standard of “no reasonable probability of adverse effects” remains intact. And even post closure trigger, EPA retains discretion to determine the timing and sequencing of closure activities based on the record support. This proposal seeks to further facts that point to specific site-based variations which validate and call for the flexible approach to regulatory approval contemplated by the WIIN Act and section 257 authority, as well the interplay between the “new tools” created by the WIIN Act and the changes to the “default federal regulatory regime,”

Waterkeeper Alliance, Inc.

Regan,

41 F.4th 654, 662 (D.C. Cir. 2022) that would be sufficient to meet RCRA's “no reasonable probability of adverse effects to human health or the environment” standard.

E. Beneficial Use of CCR

1. May 2000 Regulatory Determination on Fossil Fuel Combustion Wastes

In 2000, EPA published a final regulatory determination that addressed the management of fossil fuel combustion wastes under RCRA. In this regulatory determination, the Agency concluded that regulation as hazardous waste was not warranted for these wastes, which included coal combustion residuals. (65 FR 32214, May 22, 2000).

The 2000 determination also specifically addressed beneficial uses of CCR, acknowledging the significant environmental and economic benefits these uses can provide. Beneficial uses include a range of applications that effectively conserve natural resources and reduce disposal costs. These included construction applications such as cement, concrete, and wallboard, where the materials were encapsulated, thus minimizing exposure risks. The determination also assessed agricultural uses as lime substitutes, revealing lower risk levels than previously anticipated, thereby supporting continued exemption. In the 2000 regulatory determination, EPA states that “. . . we have decided that national regulation under subtitle C or subtitle D is not warranted for any of the other beneficial uses of coal combustion wastes.” (65 FR 32221, May 22, 2000)

2. Beneficial Use in the 2015 CCR Rule

On April 17, 2015, EPA finalized the 2015 CCR Rule to regulate the disposal of CCR as solid waste under subtitle D of RCRA (80 FR 21302, April 17, 2015). The 2015 CCR rule established national minimum criteria for classification of solid waste disposal facilities and practices, codified at 40 CFR part 257, subpart D.

In the 2015 CCR final rule, EPA retained the original 2000 Regulatory Determination for CCR that is beneficially used. (80 FR 21329). EPA also established in the final rule a beneficial use definition to distinguish between beneficial use of CCR, which is not subject to federal regulation, and the disposal of CCR, which is subject to regulation under 40 CFR part 257, subpart D (See 80 FR 21347).

The beneficial use definition is comprised of four criteria: (1) The CCR must provide a functional benefit; (2) The CCR must substitute for the use of a virgin material, conserving natural resources that would otherwise need to be obtained through practices such as extraction; (3) The use of the CCR must meet relevant product specifications, regulatory standards, or design standards, when available, and where such specifications or standards have not been established, CCR may not be used in excess quantities; and (4) When unencapsulated use of CCR involves placement on the land of 12,400 tons or more in non-roadway applications, the user must demonstrate and keep records, and provide such documentation upon request, that environmental releases to groundwater, surface water, soil, and air are comparable to or lower than those from analogous products made without CCR, or that environmental releases to groundwater, surface water, soil, and air will be at or below relevant regulatory and health-based benchmarks for human and ecological receptors during use. See: 40 CFR 257.53 and 80 FR 21349-54 (April 15, 2015). In addition, EPA stated in the preamble that “the Agency expects potential users of unencapsulated CCR below this [12,400 ton] threshold to work with the states to determine the potential risks of the proposed use at the site and to adopt the appropriate controls necessary to address the risks.” (80 FR 21353)

3. CCR Rule Litigation Related to Beneficial Use

The 2015 CCR rule was challenged by several different parties, including a coalition of regulated entities and a coalition of environmental organizations. See

USWAG et al

EPA,

No. 15-1219 (D.C. Cir.).

On September 13, 2017, EPA granted petitions from the Utility Solid Waste Activities Group (USWAG) and AES Puerto Rico LLP, requesting the Agency initiate rulemaking to reconsider certain provisions of the 2015 final rule. In light of that decision, EPA requested that the D.C. Circuit Court of Appeals hold the case in abeyance until the Agency had completed its reconsideration. EPA subsequently requested that the court remand certain provisions of the 2015 CCR rule on the grounds that the Agency was reconsidering the provisions.

Included in that remand request were two sets of provisions related to the beneficial use of CCR: (1) The 12,400-ton threshold in the beneficial use definition, and (2) The requirements for “piles” of CCR located onsite of a utility and those that are located off-site but destined for beneficial use. On August 21, 2018, the D.C. Circuit Court of Appeals granted EPA's request to remand the challenged beneficial use provisions back to EPA in order to allow the Agency to complete its administrative reconsideration.

4. Beneficial Use in the 2019 CCR Proposed Rule

On August 14, 2019, EPA published a proposed rule titled “Hazardous and Solid Waste Management System: Disposal of Coal Combustion Residuals from Electric Utilities; Enhancing Public Access to Information; Reconsideration of Beneficial Use Criteria and Piles” (84 FR 40353, August 14, 2019) (2019 CCR proposal). In the 2019 CCR proposed rule, EPA proposed to redefine the criteria for beneficial use of CCR, shifting from a 12,400-ton mass-based numerical threshold to specific location-based criteria as the threshold for requiring an environmental demonstration. This location-based approach aligned with practices observed in state beneficial use programs, which often incorporate location-based restrictions to safeguard sensitive areas (84 FR 40358-60). The rationale for this proposed change stemmed from the need to accurately identify when the use of unencapsulated CCR on the land should require further demonstration that the use does not present a reasonable probability of adverse effects on health or the environment. The previous mass-based threshold, which required a demonstration for uses exceeding 12,400 tons, was based on a unit conversion error made when evaluating data regarding landfill sizes. EPA proposed location-based criteria to reflect siting and construction considerations that more directly impacted environmental risks from CCR. These criteria included factors such as proximity to groundwater, wetlands, flood plains, and seismic zones, which were known to influence the potential for environmental releases. The Agency also requested comment on how these criteria would impact state beneficial use programs.

The 2019 CCR proposal also requested comments on whether a mass-based threshold should be retained, and if so, what the appropriate value should be. The proposal also requested comment on the possibility of using both mass-based and location-based criteria to trigger environmental demonstrations for unencapsulated CCR uses, or whether every unencapsulated use of CCR should be subject to an environmental demonstration, regardless of size or location.

Finally, the proposal requested comment on whether the beneficial use definition should include a requirement for notifying relevant parties when CCR was placed on land. This requirement could involve informing state agencies, landowners, or the public, similar to practices in some state programs.

The 2019 CCR proposal also included proposed revisions to the requirements applicable to piles of CCR. Under existing regulations, CCR piles are defined as non-containerized accumulations of solid, non-flowing CCR placed on land. This classification subjected piles of CCR to the same regulatory criteria as CCR landfills unless they are containerized or part of an off-site beneficial use.

In the 2019 CCR proposal, EPA proposed to unify the regulatory mechanism for all temporary placements of CCR on land, whether onsite or off-site, and regardless of their ultimate use for disposal or beneficial purposes, setting the standard to control releases from piles. The proposal aimed to provide a consistent mechanism to address potential environmental and health issues associated with piles of CCR, irrespective of their location or intended use, characterizing these activities as “storage” rather than disposal or beneficial use. A definition for CCR storage piles was proposed, identifying temporary accumulations of CCR that are designed and managed to control environmental releases.

The 2019 CCR proposal discussed how entities would need records documenting the removal of CCR within a specific timeline and sought comments on the feasibility of this requirement and alternative criteria for demonstrating temporary piles. Additionally, EPA proposed requirements to control releases from CCR storage piles. The proposal excluded CCR stored in enclosed structures from these requirements.

5. 2020 CCR Notice of Data Availability

On December 22, 2020, EPA published a Notice of Data Availability (NODA) titled “Hazardous and Solid Waste Management System: Disposal of Coal Combustion Residuals from Electric Utilities; Reconsideration of Beneficial Use Criteria and Piles; Notification of Data Availability”, that announced the release of new information and data related to its proposed rule published concerning CCR (85 FR 83478, December 22, 2020) (2020 CCR NODA). EPA sought public comments on whether this new data could influence the Agency's

reconsideration of the beneficial use definition and provisions for CCR accumulations. The Agency specifically requested comments on these two issues and invited additional data from the public to assist with its reconsideration. EPA clarified that it was not reopening other aspects of the proposal, CCR regulations, or previously available support documents. In addition to seeking public input, EPA shared information obtained during stakeholder meetings held between May and August 2020, which involved discussions with trade associations, utilities, environmental organizations, and state agencies.

6. Public Comments on the Fourth Beneficial Use Criterion and CCR Accumulations for the 2019 CCR Proposal and 2020 CCR NODA and EPA's Decision To Repropose

The Agency received about 130,000 total comments, including comments from a mass mailer campaign, with 60 substantively different sets of comments, on the 2019 CCR proposal reconsidering the beneficial use criteria and provisions for CCR accumulations. Generally, a few state agencies and a public interest group favored the various proposed options to revise the beneficial use criterion, but none of the options had universal support. Some states supported eliminating the mass-based threshold and replacing it with some of the specific location-based criteria to trigger an environmental demonstration which should apply to all unencapsulated uses; and an approach combining the location- and mass-based criteria. One state also suggested that an alternative criterion be allowed where state programs have location-based criteria coupled with chemical constituent limits. Other states suggested establishing a reasonable set-back distance to water supply, especially drinking water wells, by adopting a standard similar to North Carolina, which uses the seasonal high groundwater table. One state noted that removing the distinction between coal ash disposal and beneficial use could result in authorization requirements for beneficial use activities, such as permits or registrations; and suggested the Agency continue to encourage CCR beneficial use activities through self-implementing environmental protections with minimal to no permit requirements. Industry and environmental groups generally opposed the proposal to eliminate and replace the mass-based threshold with location-based criteria. The CCR users and utilities commented that the proposed revisions, including having to conduct an environmental demonstration, would discourage the beneficial use of CCR because of perceived liability concerns and financial burdens to the beneficial user. Industry also commented that changing to location-based standards from a mass-based approach shifts away from the Agency's original concern when the use of unencapsulated CCR on the land should require further demonstration that the use was not disposal and brings in smaller volume beneficial uses. The environmental groups commented that the proposed location-based criteria would weaken the current regulations by allowing any amount of unencapsulated CCR to be placed on the land as beneficial use.

Regarding EPA's 2019 CCR proposal to unify the regulatory mechanism for all temporary placements of CCR in piles, industry representatives, a state agency and the Association of State and Territorial Solid Waste Management Officials (ASTSWMO) supported consistent regulatory treatment and a single set of requirements regardless of the location.

Regarding the requirement to control releases, utilities and CCR users expressed concern about subjecting all piles, regardless of size, to the same set of storage standards. However, they supported the flexibility to choose pollution control measures that are site-specific and appropriate for conditions at the site. In contrast, environmental groups disagreed with this flexibility, requesting instead prescriptive design standards, management controls and engineer certification.

Many commenters, including states, CCR users and utilities, agreed that long-term storage of CCR in lieu of disposal should not be allowed. Nonetheless, CCR users and utilities disagreed with the proposed record-keeping requirements to document the complete removal of CCR within a specific timeline. For storage sites not in proximity to end use, the industry requested that record-keeping be limited to gross annual receipts and shipments of CCR. For sites near working end-use locations, such as cement kilns, concrete plants, wallboard manufacturing facilities, commenters argued that locations should sufficiently indicate their active status. Some states and utilities argued that any temporal requirements should better reflect the rolling basis of storage activities or be modeled after RCRA subtitle C speculative accumulation requirements. Environmental groups argued for increased enforceability and specificity through enforcement of exact timeframes.

Regarding the enclosed structure, beneficial users argued that the proposed definition is not workable and should be revised to enable CCR to be received and removed easily while ensuring effective containment. Environmental groups supported the proposed requirement for enclosed structures but also requested additional requirements to containerize liquids and specific requirements for fugitive dust control. They argued that engineer certifications were also needed for enclosed structures and that owners must be required to conduct maintenance, inspections and repairs.

On the follow-up 2020 CCR NODA, the Agency received 33 total comments. Several commenters resubmitted comments previously submitted to the Agency's 2010 CCR proposal. Generally, industry groups representing different manufacturing or production industries commented that CCR is a valuable input—these include cement and concrete producers, gypsum panel product manufacturers, and agricultural sectors. Industry also commented on the absence of damage cases associated with piles, and any beneficial use that meets the first three beneficial use criteria, concluding the fourth criterion is unnecessary. Environmental groups and citizens commented generally that piles, fill, and other unencapsulated uses involving land placement and having substantial environmental and human health impacts, can be open dumping of CCR without applicable disposal regulations.

EPA has considered all significant and relevant comments related to revising the fourth criterion of the beneficial use definition, and other issues related to beneficial use, as well as comments related to the regulation of CCR accumulations on the land that were submitted in response to the 2019 CCR Proposal and the 2020 NODA and has taken those comments into account in developing this re-proposal. If any commenter believes their previous comments on the definition of beneficial use and CCR accumulations have not been adequately addressed by this re-proposal, EPA requests the commenter re-submit their comment to this docket.

IV. What is EPA proposing?

EPA is proposing to amend the federal regulations governing the disposal of CCR in landfills and surface impoundments and defining beneficial use for CCR in 40 CFR part 257. In response to the information EPA has received during the rulemaking for the Legacy Final Rule and since the rule's publication, EPA is proposing several revisions to the existing federal CCR

regulations, which are self-implementing or implemented under a participating-State CCR program. Specifically, EPA is exempting CCR dewatering structures from regulation under part 257 and modifying the legacy CCR surface impoundment and CCRMU provisions.

Additionally, EPA is proposing to establish a new compliance pathway that allows for site-specific considerations during permitting for CCR units complying with groundwater monitoring, corrective action, and closure requirements under a federal or participating-State CCR permit. Specifically, these provisions would allow a permit authority to make site-specific determinations regarding the appropriate point of compliance for the groundwater monitoring system, site-specific cleanup levels during corrective action for constituents without a federal MCL established under §§ 141.62 and 141.66 and referenced at § 257.95(h)(1), and appropriateness of certain closure requirements while still requiring the owner or operator to ensure the unit poses no reasonable probability of adverse effects on human health and the environment.

Lastly, EPA is proposing to revise the definition of beneficial use by eliminating the requirement for an environmental demonstration for the non-roadway use of more than 12,400 tons of unencapsulated CCR on land, as well as proposing a definition of CCR storage pile, and proposing to exclude specific beneficial uses from federal CCR regulations.

In addition to the proposals above, EPA is providing notice that in a future separate action, EPA will reopen the public comment period for the Federal CCR permit program proposed rule entitled

Hazardous and Solid Waste Management System: Disposal of Coal Combustion Residuals From Electric Utilities; Federal CCR Permit Program

(85 FR 9940) for a period of 30 days. The public comment period ended on that proposal on August 7, 2020. EPA will reopen the comment period in a future separate action under Docket ID No. EPA-HQ-OLEM-2019-0361 to provide the public with an opportunity to provide input on whether their views of the proposed Federal CCR Permit Program have altered in the intervening years, for example, in light of new information or considering the revisions proposed in this action.

A. Amendments to the Self-Implementing Regulations

As discussed in Units III.A. and III.D. of this preamble, the 2015 CCR Rule established national requirements for CCR disposal under a self-implementing regulatory structure. Since the promulgation of the 2015 CCR Rule, the 2016 WIIN Act authorized EPA to approve State CCR permit programs and implement a permit program for EPA to serve as the permit authority. 42 U.S.C. 6945(d). In accordance with RCRA sections 4005(d)(3)(A) and 4005(d)(6), in the absence of a permit issued under a participating-State program, the owner or operator of a CCR unit must continue to comply with the self-implementing Federal CCR regulations until a permit from a CCR permit authority (

i.e.,

an EPA-approved State CCR permit program or EPA) that includes these provisions is in effect. 42 U.S.C. 6945(d)(3)(A), (d)(6). For a State with an approved CCR permit program (

i.e.,

Oklahoma, Georgia, Texas, North Dakota), before the State can issue a permit or permit modification for a CCR unit that operates in lieu of the amended regulations from this rulemaking, the State must adopt either the federal standards or alternative technical standards that are at least as protective as the amended Federal CCR regulations, submit an application for approval of the new provisions to the Agency, and receive EPA approval for the new provisions. EPA will work closely with States throughout this process to expedite reapproval of amended provisions.

Since publication of the Legacy Final Rule, EPA received information from numerous companies and representatives of industry regarding the scope of the deferrals within the Legacy Final Rule, the scope of the CCRMU universe, challenges complying with the existing CCR requirements, and requests for regulatory changes. Based on this information provided to EPA, as described in greater detail below, and the conclusions described in Unit III.D., EPA is proposing several amendments to the existing CCR requirements. Specifically, EPA is proposing to: define and exempt CCR dewatering structures from regulation under part 257; broaden the criteria for the closure by removal certification for legacy CCR surface impoundments; broaden the deferral criteria for legacy CCR surface impoundments that have completed closure under a regulatory authority prior to November 8, 2024; amend the scope of the CCRMU regulations; and clarify the deadline for new CCR landfills, CCR surface impoundments, and lateral expansions to comply with the requirements to conduct background sampling. EPA is also soliciting comment on several provisions, including on the need to finalize the 2018 proposed performance standard for more specific slope protection requirements for existing and new surface impoundments.

1. CCR Dewatering Structures

EPA is proposing a definition for “CCR dewatering structures” at § 257.53 and making other clarifying edits to § 257.53 to explicitly state that a dewatering structure meeting this definition would not be classified as a CCR surface impoundment or a CCRMU. During implementation of the CCR program, questions have arisen as to the appropriate standards that should apply to certain concrete basins used as settling ponds for CCR.

Specifically, owners or operators have expressed uncertainty regarding whether dewatering structures are subject to the surface impoundment requirements in the existing federal CCR regulations and have argued that the surface impoundment regulations are unnecessary. While EPA previously took the position that, under the current regulations, these structures are surface impoundments,

EPA has reconsidered that position and believes that regulation as CCR surface impoundments is inappropriate based on a reevaluation of the risk these structures present. This proposal will provide greater flexibility by revising the regulation to provide that these structures: (1) Are not CCR surface impoundments and are CCR dewatering structures as defined in this proposal and (2) As CCR dewatering structures, are not regulated under the federal CCR regulations.

PacificCorp 2025a. Letter from Brett Shakespear, Director, Environmental Compliance and Remediation to Linda Jacobson, EPA Region 8 RCRA Enforcement Section. Re: NEIC Civil Investigation Report Hunter Power Plant, Castle Dale, Utah. October.

See, for example, Electric Energy, 106 F.4th 31, 42 (2024).

The containment structures in question are used for dewatering CCR to enable CCR solids to be landfilled and are commonly referred to as holding basins, scrubber drying basins, fly ash washdown basins, tanks, or settling ponds. Under the proposed definition, CCR dewatering structures are designed to

temporarily

contain an accumulation of CCR and therefore involve storage, rather than disposal, for the purposes of the CCR regulations. See definition of “disposal” in § 257.53, which states, “For purposes of this subpart, disposal does not include the storage or the beneficial use of CCR.” Based on the Agency's work with CCR, it is EPA's current understanding that the use of CCR dewatering structures is a common

practice across the industry. In fact, the use of dewatering structures is necessary if CCR is to be landfilled. The dewatering process, including the use of these structures, plays a critical role in efficiently managing CCR by reducing moisture content, thereby facilitating easier handling. Dewatering typically serves as an interim step, or steps, prior to disposal in a landfill or shipment for beneficial use. Dewatering structures are specifically engineered to allow for the CCR to dry and result in CCR being easier to handle when moving to disposal in a landfill or being beneficially used. Typically, these structures are made of concrete or other similar material. Their purpose is to dewater wet CCR, not to serve as long-term storage or disposal of CCR. Given this use and function, EPA is now concluding that CCR dewatering structures are different from surface impoundments due to the fundamental differences in their design and function. Surface impoundments usually involve the long-term containment of liquid waste, typically with a significant hydraulic head, which poses a higher risk of seepage and contamination of groundwater resources. Periodically, once sufficient dewatering has occurred, the CCR in these structures will be removed and transported to a CCR or permitted MSW landfill or beneficial use location—another key distinction from surface impoundments that was not fully recognized during the prior rulemaking. As such, clarifying the regulatory status of these dewatering structures is appropriate in this rulemaking.

To create a clear regulatory separation between these CCR dewatering structures and CCR surface impoundments, EPA is proposing to create a new definition for “CCR dewatering structures” in 40 CFR part 257. EPA proposes to define CCR dewatering structures as “a stationary device, designed to temporarily contain an accumulation of CCR which is constructed of non-earthen materials (

e.g.,

concrete, steel, plastic). The device must be used primarily for dewatering CCR waste to facilitate disposal of CCR solids elsewhere.” Accordingly, and to provide greater clarity, EPA also proposes to amend the definition of CCR surface impoundment to note that a containment structure meeting this newly proposed definition of a CCR dewatering structure is not a surface impoundment.

In addition to more appropriately calibrating the level of regulation that is appropriate for these structures, this proposed change enables more owner or operators to dewater their CCR prior to disposal (

i.e.

landfilling the CCR instead of disposal in surface impoundments). The landfill in which the CCR is ultimately disposed must meet all applicable part 257 or 258 requirements.

EPA expects this change would not produce a reasonable probability of adverse effects on health or the environment. This expectation is informed by a reconsideration of determinations in the initial 2014 Risk Assessment as well as EPA's understanding of the size and use of these structures. During the 2015 CCR Rule, EPA considered related issues which EPA has since reevaluated. First, EPA considered whether the definition of a CCR surface impoundment should include “temporary” units that are not designed to hold an accumulation of CCR such as downstream secondary and tertiary surface impoundments, such as polishing, cooling, wastewater and holding ponds. EPA reasoned, at the time, that those units are unlikely to ever be completely dredged of CCR and are likely to have large quantities of CCR impounded with water under a hydraulic head will be managed for extended periods of time. As such, EPA concluded, these units present the same risks as permanent disposal units. (50 FR 21357) Second, in the risk assessment supporting the 2015 CCR Rule, EPA modeled units with concrete liners as equivalent to unlined units because of the expectation that cracks could lead to uncontrolled leakage and the difficulties of repairing any issues with the concrete liner.

However, with specific real-world examples arising during implementation, EPA is reconsidering some of these conclusions. First, EPA notes that these conclusions do not account for the fact that concrete containment structures would, by design and function normally be much smaller than a CCR surface impoundment. The several examples of CCR dewatering structures of which EPA is currently aware range from approximately 0.02-2.2 acres in size. The average size of these structure is 0.77 acres with thea median size of 0.4 acres.

By comparison, the average and median size of CCR surface impoundments regulated under the 2015 CCR Rule is 54.2 and 24.0 acres, respectively. While surface impoundments do vary widely in size, on average they are considerably larger than a CCR dewatering structure.

The smaller amount of CCR that is accumulated in these structures along with the lower hydraulic head resulting from the significantly smaller unit size suggests the risk to be lower, with other conditions remaining the same. Further, the EPA acknowledges the previous determination that concrete containment structures were equivalent to unlined units was not based on actual data of leakage rates from concrete containment structures.

See Memo to record re: CCR dewatering structures. January 2026.

See 89 FR 38958 for a discussion of available information on various CCR unit sizes.

The information available to EPA indicates these structures are made of concrete and are enclosed on three sides with a concrete bottom liner. The bottom liner covers the entire surface that may come in contact with CCR containing liquid during the dewatering cycle. This fact distinguishes these structures from unlined units or units only partially lined with concrete (

e.g.,

employing a concrete revetment mat or employing only a concrete apron and vehicle ramp).

These concrete dewatering structures are designed for temporary accumulation and are periodically dredged, and CCR removed. As discussed above, the management practices typically conducted in these structures would not meet the definition of “disposal” and no long-term encapsulation or containment of CCR is expected to occur in these structures. Under the proposed definition of these units, only the temporary containment of an accumulation of CCR for “for disposal elsewhere” would occur. The structures are utilized in a process step (dewatering) critical to efficiently managing CCR by reducing moisture content, thereby facilitating easier handling. Dewatering in these structures serves as an interim step, or steps, prior to disposal in a landfill or shipment for beneficial use. Dewatering structures are specifically engineered to allow for the CCR to dry and result in CCR being easier to handle when moving to disposal in a landfill or being beneficially used. As such, at the end of their life no CCR should remain in the containment structures. EPA also expects the periodic dredging and emptying of the dewatering structures at the end of each dewatering cycle will provide an opportunity for some visual inspection of the structures to identify significant cracks or other failures in the engineered structure. Based on EPA's understanding, these distinctions suggest a lower risk for these structures than EPA estimated in the 2014 Risk Assessment.

Additionally, EPA now also has a greater appreciation for the various standards used in the concrete industry. For example, the American Concrete Institute has standards and commentary

for concrete structures used in environmental engineering. The standards cover the structural design, materials selection, and construction of environmental engineering concrete structures. The standards account for the fact that concrete structures used for conveying, storing, or treating liquid or solid wastes are subject to uniquely different loadings, more severe exposure conditions, and more restrictive serviceability requirements than non-environmental building structures.

While these standards are not legally binding, they illustrate the expertise in the concrete industry and the refinement of concrete formulations, and methods for specific applications. Notably, the commentary provides substantial guidance and best practices to assure liquid-tightness of concrete structures.

American Concrete Institute. “Code Requirements for Environmental Engineering Concrete Structures (ACI 350-06) and Commentary” 2006.

Ibid, pg. 350-3.

Furthermore, developments in material science have yielded advancements in concrete technology. A 2023 review of available literature concluded that concrete technology had undergone remarkable advancements in the preceding decade, encompassing novel materials, sustainable practices, durability enhancements, and advanced manufacturing techniques. The review notes the developments offer improved performance, sustainability, and construction efficiency. The review also concluded that the introduction of novel materials, such as additives, fibers, and fillers, has led to enhanced properties in concrete, including increased strength, ductility, and crack resistance.

A 2025 study also found that self-healing concrete formulations improve concrete structure longevity. Specifically, the authors of the study found high crack healing efficiency in self-healing concrete that can also extend service life of concrete structures.

Based on its experience with these industries, EPA expects owners or operators will have incorporated recognized and generally accepted good engineering practices in the design and construction of these structures. Therefore, EPA likely overstated the risks in 2014 of these comparatively small units with concrete liners. EPA is thus proposing these containment structures be considered CCR dewatering structures, not CCR surface impoundments and that they are not subject to the requirements for surface impoundments in 40 CFR part 257, subpart D.

Ajwad, A (2023) Concrete Evolution: An Analysis of Recent Advancements and Innovations. Fifth Conference on Sustainability in Civil Engineering (CSCE'23) Department of Civil Engineering Capital University of Science and Technology, Islamabad Pakistan.

https://csce.cust.edu.pk/archive/CSCE_23_conference_proceedings/2023-135.pdf

Olaboye, O. S. (2025) Advancements in Self-Healing Concrete: Enhancing Durability and Reducing Maintenance Costs.

American Journal of Engineering Research,

Vol 14 (issue 2) pp 25-34.

In implementation, the key to distinguishing these dewatering structures from surface impoundments would be whether the structure in question was: (1) Used for temporary accumulation of CCR for the primary purpose of dewatering the CCR and (2) Built with non-earthen materials. If the containment structure meets both criteria above, it is considered a CCR dewatering structure under 40 CFR part 257. If not, the structure would be a CCR surface impoundment as defined in § 257.53.

To develop a more comprehensive understanding of the prevalence and nature of structures that would meet the proposed definition of a CCR dewatering structure, EPA is soliciting comment on the number of structures that meet the proposed definition and their locations. EPA specifically requests information about: (1) the location of these structures, including the state, facility name, and precise location at the facility, (2) specifics about the design, including if professional engineer certified the designs, the size of the unit, and expected operational life, (3) specifics about the construction, including the date of construction and materials used, (4) specifics about the materials that were used, including any relevant standards or specifications for the material (

e.g.,

ASTM or ACI), (5) any expected or routine maintenance required to keep the structure operating as intended, including specifics regarding the maintenance performed and the frequency, and (6) specifics about the operation of these structures (

e.g.,

average dewatering cycle times, frequency of inspections conducted, or any other relevant information). Additionally, EPA requests information on the environmental regulation and impact of these structures, including any known incidents of leakage or contamination, state or local oversight of these units, or monitoring or reporting mechanisms in place. Further, EPA requests comment on what, if any, additional criteria should be incorporated into the proposed definition of CCR dewatering structures. For example, should the definition of CCR dewatering structure specify the structure be completely enclosed on three sides or that the non-earthen material have a hydraulic conductivity of no more than 1 × 10

−7

cm/sec, as required for composite or alternative composite liners for new CCR units? See § 257.70(b) and (c). Should the definition require the unit be located in a location whereby any releases would be detected by the facility's groundwater monitoring system (

i.e.,

covered as part of a multi-unit system)? Should the definition include certain operational standards or practices that would need to be adhered to in order to be a CCR dewatering structure, such as: routine visual inspection of the concrete structure (

i.e.,

at the end of every dewatering cycle) to identify and address visually apparent cracks, spalls, or issues with sealants and joint condition to help ensure the liquid tightness of the concrete structure; daily inspections of ancillary equipment (

e.g.,

piping, valves, pumps) to help prevent leaks, spills or overtopping caused by equipment failure or human error; maintaining a minimum freeboard throughout the dewatering cycle to prevent overtopping and associated potential runoff; or biennial cleanouts of the structures including pressure washing to decontaminate the unit and allow for more detailed inspection and repair of the concrete slab and joints to ensure liquid tightness of the concrete and greatly reduce the risk of leaking? EPA requests comment on whether these operational requirements would be appropriate or necessary to ensure no adverse effect on health and the environment as part of exempting these units from regulation as CCR surface impoundments.

Finally, to provide as clear a definition as possible, EPA also requests comment on the proposed definition of CCR dewatering structure. EPA specifically solicits feedback regarding how to better distinguish between these temporary dewatering structures and composite lined surface impoundments, such as incorporating explicit parameters regarding what constitutes “temporary” containment of an accumulation of CCR. If so, EPA request input regarding the specifics of those parameters (

e.g.,

what length of time should constitute “temporary”).

This information is anticipated to help the Agency validate or calibrate its proposed approach (

i.e.,

exempting these CCR dewatering structures from Federal regulation as a CCR surface impoundment). The Agency believes this is worthwhile given that most of the information EPA currently has on these structures are from a relatively small subset of facilities compared to the total universe. Gathering broader data will help ensure that the decision in the final

rule considered a more comprehensive set of information.

2. Legacy CCR Surface Impoundments

Since publication of the Legacy Final Rule, EPA has received information from States and regulated entities about the adequacy of closures of legacy CCR surface impoundments and CCRMU completed prior to November 8, 2024.

These entities have stated that this information demonstrates that closures performed under State oversight are protective of human health and the environment. Therefore, EPA is proposing to create another option in § 257.100(g) for owners and operators to certify closures of legacy CCR surface impoundments by removal that have been completed prior to November 8, 2024 and to expand the deferral criteria in § 257.101(g) for legacy CCR surface impoundments and CCRMU that completed closure prior to November 8, 2024 under oversight by a regulatory authority (

i.e.,

State or federal program).

This is the effective date of the Legacy Final Rule.

a. Certification of Closure by Removal for Legacy CCR Surface Impoundments

EPA is proposing to establish an additional option in § 257.100(g) for owners and operators to certify the closure of legacy CCR surface impoundments by removal, provided these closures were completed prior to November 8, 2024, under the oversight of a regulatory authority.

The Legacy Final Rule established a pathway for legacy CCR surface impoundments that closed by removal before November 8, 2024, allowing them to certify and document their closure as having met the performance standards in § 257.102(c) See § 257.100(g). Successfully documented and certified closures by removal would exempt these legacy surface impoundments from further requirements under 40 CFR part 257, subpart D. This decision was made to avoid requiring owners or operators of legacy surface impoundments that had completed closure in a manner that met the performance standards in § 257.102(c), to comply with additional subtitle D requirements which would not result in health or environmental benefits. Under the regulations promulgated at § 257.100(g), the following information is required to make the certification:

• The type and volume of CCR and all other materials in the unit prior to closure;

• The methods used to verify complete removal of all CCR and other contaminated materials from the unit, including any post-removal sampling and analysis;

• Documentation that all CCR and other contaminated materials were removed from the unit, including, the results of any post-removal sampling and analysis that was conducted;

• The methods used to verify complete decontamination of all areas affected by releases from the unit, including but not limited to post-decontamination sampling and analysis;

• Documentation that all areas affected by releases from the unit were decontaminated and that all groundwater affected by releases has achieved groundwater protection standards; and

• Documentation that groundwater monitoring data concentrations of each appendix IV constituent do not exceed the relevant groundwater protection standard, which would be either the federal MCL or background concentration, for two consecutive sampling events, consistent with §§ 257.95(e) and (h). Additionally, the owner or operator must include documentation that the system meets a subset of performance standards at §§ 257.91(a) through (e), 257.93(a) through (d), and 257.93(i) codified at §§ 257.100(g)(6)(i) through (vii).

This avenue to closure by removal certification for legacy impoundments is a viable path for some legacy surface impoundments, in particular, units that had groundwater monitoring systems and data to demonstrate constituent concentrations do not exceed the groundwater protection standard established at § 257.95(h). The Agency intends for this avenue to remain in effect and is not proposing to revise this provision. Maintaining this avenue avoids potential disruption for owners and operators that have already made such demonstrations.

However, several public comments on the Legacy Proposed Rule requested greater flexibility in closure by removal certification for legacy impoundments, specifically advocating for all closures by removal approved by a State or regulator under other authorities (

e.g.,

State solid waste programs) to also qualify for certification. During finalization of the Legacy Final Rule, EPA did not adopt this suggestion due to a lack of documented factual and legal basis for States' decisions, which prevented EPA from concluding that all State-approved closures by removal posed no reasonable probability of adverse effects on health or the environment, as mandated by RCRA section 4004(a). (89 FR 39009) While concluding all State-approved closure met the RCRA protectiveness standard was not appropriate, EPA acknowledges that additional flexibility in the closure by removal certification criteria may be warranted in certain instances.

Since publication, EPA has received information from members of the regulated community to support the expansion of the closure by removal certification criteria and the conclusion that closure performed under State oversight meets the RCRA protectiveness standard. Upon reconsideration, EPA reviewed pertinent information, including public comments on the Legacy Proposed Rule, and the information received post-finalization of the Legacy Final Rule, including examples of State-overseen closures in Kentucky, North Carolina, South Carolina, and Georgia.

In Kentucky, the State's Division of Waste Management (KDWM) oversaw the closure by removal of three legacy impoundments at the Dale power generation facility between 2014 and 2019. KDWM approved the closure plan, conducted at least 16 onsite inspections including three inspections of the units to verify “clean closure” down to native soils. KDWM spent over 350 hours overseeing the closure.

At Duke's Riverbend plant, North Carolina required and oversaw the closure by removal of 5.35 million tons of CCR between 2014 and 2019. The impoundments were dewatered, the ash excavated, and the area regraded and seeded with grass. The State also requires annual stability inspections, a groundwater monitoring program with over 140 wells, and a corrective action program to continue at the two now closed legacy impoundments. EPA independently verified that North Carolina's Coal Ash Management Act (CAMA) requires closure of all unlined impoundments, including those at inactive facilities that would qualify as legacy CCR surface impoundments. Further, review of publicly available documentation from Duke Energy, the owner of all legacy impoundments in the state, indicates the presence of state orders-on-consent requiring corrective action for these units.

Between 2012 and 2020, South Carolina oversaw the closure by removal of two CCR surface impoundments at the Granger facility. The owner or operator removed all the CCR along with an additional foot of underlying soil from both inactive impoundments. The removal of CCR from the two impoundments was performed under the supervision of the South Carolina Department of Health and Environmental Control (SCDHEC) and in accordance with the requirements established by a detailed CCR closure

plan also approved by SCDHEC. The closure plan also required comprehensive soil sampling to ensure the decontamination of the remaining soil across both impoundments. Post-closure groundwater monitoring—required by the State—will continue until all relevant constituents meet, and stabilize at or below, their applicable MCL, as established by SCDHEC. EPA's own research found that the legacy CCR surface impoundments in South Carolina are already undergoing or have undergone closure and, if needed, corrective action consistent with the requirements of the legacy rule.

In a fourth example of information provided to EPA regarding closure by removal of legacy CCR surface impoundments under State oversight, Georgia oversaw the closure by removal of an ash pond at the Kraft plant through the State's Response and Remediation Program between 2015 and 2021. The State approved the soil and groundwater at the unit as protective of human health and the environment in 2021. EPA also received comments on the Legacy Proposal that offered a few examples of closures that the commenters believed were substantially equivalent to closures completed in accordance with § 257.102, because they involved substantial regulatory oversight, a site-specific risk assessment, and general consistency between the programs on the standards to be applied. These included closures under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and an approved State's RCRA subtitle C program. Another commenter, Duke Energy, provided a copy of a 2020 Consent Order entered in State court governing the closure of CCR surface impoundments at seven sites across the State. The utility also provided copies of several human health and ecological risk assessments that were conducted to support the State's approval of the closures, along with various third-party reports. The commenter concluded that based on this record, it is unnecessary to subject CCR units that closed under any other regulatory programs to the existing closure criteria for CCR surface impoundments in §§ 257.101 and 257.102. While these examples aren't specific to closure by removal, the commenters were intending to illustrate that these other regulatory authorities provide detailed and meaningful oversight to address risk posed by the CCR units in a site-specific, tailored approach and therefore, additional Federal requirements are not necessary and would not result in health or environmental benefits.

As stated in the Legacy Final Rule, EPA agrees that closures conducted as part of a CERCLA or RCRA subtitle C response action would normally be expected to be consistent with the performance standards in § 257.102. The CCR closure regulations were based on the closure regulations for hazardous waste facilities, and the CCR regulations would normally be considered applicable or relevant and appropriate requirements (ARARs) under CERCLA for any closure of a CCR facility after 2015. EPA further acknowledged that these closures are not the only closures that may be equally as protective as those conducted under the Federal CCR requirements. (89 FR 39030).

In the Legacy Final Rule, EPA finalized requirements to monitor groundwater to ensure the closure fully addressed any risk to the groundwater. However, based on the information provided to EPA regarding the level of regulatory oversight during and after these previous closures, and the cases made by commenters regarding the ability of permit authorities to adequately address risk in a site-specific way, EPA now concludes that requiring groundwater monitoring is not the only way to assess potential risk to groundwater and ensure closures pose no reasonable probability of adverse effects to health and the environment. For example, a State may have overseen the closure by removal of a legacy surface impoundment and determined, based on state legislation, risk assessments, site-specific facts, or models, that groundwater monitoring was not necessary to conclude that the closure did not pose a reasonable probability of adverse effects to health or the environment. Such a unit would not be eligible to certify the closure by removal under the current regulations. However, EPA concludes that additional closure activities are not warranted as long as the impacts to groundwater were considered prior to or during the closure, even if the authority determined groundwater monitoring was not necessary.

This pathway to closure by removal certification ensures no reasonable probability of adverse effects on health or the environment, in part, by requiring state oversight of previously conducted closures by removal. State oversight of the closure by removal should ensure that all CCR were removed from the surface impoundment and, thus, no source of contamination would remain at the unit. This pathway thus ensures the sources of additional pollution were eliminated. The pathway, additionally, provides for consideration of groundwater and state oversight of any necessary corrective action. Identified existing contamination (

i.e.,

that originating prior to all CCR being removed) could be addressed by corrective action, as deemed necessary by the state.

Therefore, based on the above considerations and information, as well as the conclusions discussed in Unit III.D. regarding the ability of EPA to allow for non-uniformity in attainment of the baseline RCRA standard of protection, EPA is proposing to codify another option for owners and operators to certify closure of legacy CCR surface impoundments by removal at § 257.100(g).

Under this option, owners or operators must demonstrate the closure was completed under the oversight of another regulatory authority prior to November 8, 2024, the authority considered impacts to the groundwater, and oversaw any necessary corrective action. Adding a third avenue for certification of closure by removal for legacy surface impoundments that have completed closure by removal under state or Federal oversight prior to November 8, 2024, credits owners and operators' good faith efforts to comply with closure requirements for legacy surface impoundment imposed by other regulatory authorities prior to the Legacy Final Rule's effective date. Additionally, this avoids duplicative regulation that could cause uncertainty, delay, or require redoing closure work that was approved by another regulatory authority. The proposed change would address the state closure scenario described above and others where a State or other regulatory authority—during the active oversight of the legacy CCR surface impoundment closure—determined the closure by removal would not present a reasonable probability of adverse effects to health or the environment, even without requiring groundwater monitoring.

The regulations already contain two pathways for owners and operators of legacy surface impoundments to certify closure by removal (

i.e.,

§ 257.100(g)(1)-(6) for those with available groundwater data and § 257.100(h) for those units that needed to conduct additional groundwater monitoring). This proposal would not affect these two existing certification avenues. The proposed third avenue for certification of closure by removal is an additional avenue not intended to disrupt, supersede, or otherwise alter the two existing avenues.

To effectuate this change, EPA is proposing to modify § 257.100(g) to provide another avenue to certify the closure by removal for legacy surface impoundments. This proposal would not affect those who completed the certification under the existing

regulations no later than November 8, 2024. If finalized, this proposal would provide the option for an owner or operator of a legacy CCR surface impoundment that completed closure of the CCR unit by removal of waste prior to November 8, 2024, to complete a closure certification that includes information regarding a regulator-approved closure by removal and any necessary corrective action conducted pursuant to an enforceable requirement. The documentation would need to demonstrate that the regulator played in active role in overseeing and approving the closure by removal, considered impacts to groundwater, and oversaw and approved any necessary corrective action. The consideration of groundwater impacts is important to ensure that the potential risks to groundwater were evaluated by the State or other regulatory authority. This may take the form of site-specific information (

e.g.,

groundwater monitoring data, receptor surveys, groundwater modeling, or a risk assessment) or statewide decision that groundwater monitoring is not necessary (

e.g.,

state legislation stating as much). Instances of a regulatory authority providing active oversight and approval of a closure could include closure by removal conducted under a State or Federal permit, an administrative order, or consent order issued on after October 19, 2015 under CERCLA or by an EPA-approved RCRA State program.

The October 19, 2015 date is the effective date of the 2015 CCR Rule which established national standards for CCR management, including closure. EPA believes this date is appropriate as the owners and operators conducting these closures, and regulators overseeing the closures, would have been cognizant of the Federal CCR closure standards. Moreover, for orders issued under CERCLA after that date, the Federal CCR management standards would have been ARARs. As such, this date helps ensure that the closures conducted under these alternate programs are unlikely to result in a reasonable probability of adverse effects on health and the environment.

EPA is proposing to require the certification of closure by removal under the oversight of a regulatory authority including the supporting information, be completed within six months of the publication date of the final rule, if finalized. This compliance timeframe was used for the original closure by removal certification at § 257.100(g). EPA expects this will provide ample time for owners and operators to prepare the necessary documentation of State oversight of their closure by removal.

In acknowledgement of the additional information received, and to realize the benefits described above, this proposal allows owners and operators to rely on prior determinations of the State and other regulatory authorities to meet the federal standards. At the same time, due to the practical limitations and inherent uncertainty related to the record, EPA requests comment on the adequacy of the record for this aspect of the proposal, and, to the extent any gaps are identified, requests suggestions for sources of additional information. As described above, during the rulemaking for the Legacy Rule, the Agency had received information to demonstrate that previous closure decisions made under State or other regulatory authorities will protect human health and the environment. Since promulgation of the Legacy Final Rule, the Agency received additional information describing a handful of State programs and several individual, site-specific closure decisions. EPA requests comment on whether these closures are representative of closures performed at other sites and in other States. Specifically, EPA would like to know if there is additional information the Agency should consider, or other issues of which EPA should be aware. For example, EPA encourages commenters to submit specific case studies or examples where State or other regulatory authority decisions have been effective or ineffective in ensuring protective closures. Additionally, EPA seeks empirical data or studies that compare the effectiveness of State and federal CCR closure requirements or information describing specific elements of State regulatory frameworks that may differ from federal requirements and how these differences impact closure outcomes. EPA will consider such information submitted as it develops the final action.

Based on this additional information and the policy rationale described above, EPA is proposing to provide an additional option for owners and operators to certify closure of legacy CCR surface impoundments by removal, provided they were completed under the oversight of another regulatory authority.

Solicitation of comment.

Additionally, EPA is requesting comment on whether the proposed additional certification of closure by removal avenue allows for legacy impoundments to have been closed under a sufficiently broad suite of scenarios. As described above, the proposed approach would require the owner or operator of a legacy impoundment to submit documentation that a regulatory authority played an active role in overseeing and approving the closure by removal and any necessary corrective action, pursuant to an enforceable requirement issued on or after October 19, 2015. This includes a State or Federal permit, an administrative order, or consent order under CERCLA or by an EPA-approved RCRA State program.

However, during the development of the proposed rule, EPA received input from a subset of utilities requesting a broader suite of former closures be eligible for this certification process. One utility requested EPA to remove the requirement that the closure and any necessary corrective action be pursuant to an enforceable requirement. This change would allow legacy impoundments conducted under voluntary cleanup programs to be eligible for this certification pathway. A second utility suggested removing the stipulation that the enforceable requirements have been issued after October 19, 2015. This would allow for closures conducted before the existence of the 2015 CCR Rule to be eligible for the closure by removal certification. Removing these restrictions on when the closure and corrective action were required and the types of programs that could have overseen the closure of these units would come with certain tradeoffs.

Benefits of this additional flexibility would include a greater number of legacy impoundments eligible for this certification and thus greater regulatory certainty and continuity. Units that were closed by removal in a protective manner—regardless of timing of the closures and whether they were closed under a voluntary program—would not be required to conduct additional closure activities that don't offer additional protection or benefits. The primary disadvantage is that some of those units closed pre-2015 and under a voluntary program may not have been closed in a comparable manner to that required under the Federal program and possibly with no meaningful oversight. As a practical matter, in such scenarios, there may be less documentation available as to the closure and corrective action activities performed. Relatedly, there may also be less assurance that all the closures previously conducted under such broad criteria would ensure there will be “no reasonable probability of adverse effects on health or the environment.” For example, the level of oversight under voluntary programs may vary between States and over time. In some States, the voluntary closure may entail significant oversight, (

e.g.,

regulator review and approval of the closure and groundwater monitoring plans, review of groundwater monitoring data) but not necessarily in all States or in all time periods in which these closures were performed. At the same time, if the owner or operator could demonstrate there was meaningful oversight of the closure and corrective action activities conducted (which would still be required under this alternative), it may be reasonable to assume the closure would be protective.

EPA requests comment on whether the Agency's proposed criteria for State and other regulatory programs is appropriate and whether the two suggestions from commenters described here should be finalized. EPA is also seeking comment on specific criteria that voluntary programs should meet for units closed under their oversight to be eligible for this certification. The Agency also requests examples of successful closures under voluntary programs that could inform EPA's final decision. EPA also requests if any other documentation may be appropriate to require to demonstrate the protectiveness of closures conducted pre-2015 or under a voluntary program. EPA will consider public comments and, if the comments are sufficiently supportive, may finalize these additional closure by removal certification paths.

b. Deferral of Certain Legacy CCR Surface Impoundment Closures To Permitting

EPA is proposing changes to § 257.101(g) to expand the deferral criteria for legacy CCR surface impoundments that completed closure of the unit under state or federal regulatory authority prior to November 8, 2024. This expansion will allow owners and operators to rely on the decisions of State and other regulatory authorities regarding legacy impoundment closures conducted prior to the effective date of the Legacy Final Rule to meet the federal standards—until the CCR permitting authority can consider, on a site-specific basis, the need for additional closure measures to be taken. This expansion does not eliminate the requirements for groundwater monitoring and corrective action of releases from the unit.

In the Legacy Final Rule, EPA finalized provisions allowing owners and operators of legacy surface impoundments to defer compliance with the closure performance standard until the CCR permit authority could make a site-specific decision regarding the adequacy of the closure, provided the owner or operator could document that the unit closure met certain conditions. This provision allowed the permit authority to evaluate site-specific information and determine whether a closure performed before the effective date of the Legacy Final Rule met the appropriate part 257 closure standards. As explained in the Legacy Final Rule, EPA did not want to require facilities that had completed closure prior to November 8, 2024, to “reclose” if the closure conducted was protective of human health and the environment and requiring compliance with additional subtitle D requirements would not result in health or environmental benefits. At the time of the Legacy Final Rule, EPA recognized that some closures would have been done in a manner that achieved a similar outcome to the closure performance standards in § 257.102, while others would not have. At the same time, however, EPA did not believe that it could develop nationally applicable criteria that were sufficiently precise that regulated entities could determine whether the alternative requirements ultimately accomplish the same environmental goals and meet the same performance standards as the Federal requirements. Accordingly, the Legacy Final Rule provided the avenue at § 257.101(g) for owners and operators of legacy impoundments to defer closure determinations until the CCR permit authority could make a site-specific decision.

Specifically, the Legacy Final Rule provided that an owner or operator of a legacy CCR surface impoundment need not demonstrate compliance with the closure performance standards in § 257.102(c) or (d) provided they demonstrate that the closure of the CCR unit met a specified list of standards codified in § 257.101(g). These standards are:

(1) The owner or operator of the CCR unit must document that a regulatory authority played an active role in overseeing and approving the closure and any necessary corrective action, pursuant to an enforceable requirement. This includes a state or Federal permit, an administrative order, or consent order issued after 2015 under CERCLA or by an EPA-approved RCRA state program.

(2) The owner or operator of the CCR unit must document that the regulatory authority required or conducted a site-specific risk assessment prior to (or as part of) approving the closure and any necessary corrective action.

(3) The owner or operator of the CCR unit must document that it installed a groundwater monitoring system and performed groundwater monitoring that meets all of the following:

(i) Was capable of accurately representing background water quality;

(ii) Was capable of accurately representing the quality of water passing the waste boundary;

(iii) Was capable of detecting contamination in the uppermost aquifer; and

(iv) Monitored all potential contaminant pathways.

(4) Must document that the closed unit meets either:

(i) The performance standard in § 257.60; or

(ii) The performance standard in § 257.102(d)(2)(i).

(5) The owner or operator must also include a certification statement as to the veracity of the information.

These standards are intended to ensure protectiveness at least until the time a permit authority could evaluate the closure on a site-specific basis to determine if the closure is as protective as those conducted in accordance with § 257.102. The existing provisions require the owner or operator to submit a permit application to the permit authority with sufficient information, including groundwater data, to demonstrate the applicable closure standards had been met. Under the existing regulations, the permit authority will then review the information to determine whether the “equivalency” of the closure has been successfully demonstrated. If EPA or a Participating State Director determines that the closure has met the appropriate part 257 closure standard, the permit authority will issue a permit to require compliance with applicable post-closure requirements. If the permit authority determines that the closure does not meet the appropriate part 257 standards, the owner or operator will be required to submit a complete permit application and obtain a permit that contains the specific requirements necessary for the unit to achieve compliance with the closure requirements at § 257.102.

During the Legacy Rulemaking, EPA received public comment arguing that state programs had become significantly more robust over the past couple of decades, especially, since 2015 when EPA last conducted a review of state programs. For example, Duke Energy provided information on North Carolina's CCR program. The utility claimed that there are no gaps within the state program including with respect to legacy surface impoundments. Duke Energy further stated that the state's groundwater rules establish robust groundwater monitoring and corrective action programs. The company went on to describe aspects of the state's program that, it argues, as applied to

two of its facilities, (

i.e.,

the Riverbend and Cape Fear facilities), results in stringent oversight by North Carolina Department of Environmental Quality (NCDEQ).

Specifically, Duke Energy notes that with respect to Riverbend, the state's Coal Ash Management Act (CAMA) prescribed the closure method (

i.e.,

closure by removal), Sess. L. 2014-122, §§ 3.(b)(2), (c)(1), (2), and mandated that impacted groundwater be restored in accordance with the act's groundwater assessment and corrective action provisions. As for Cape Fear, the utility notes that CAMA required closure plans for all the company's impoundments not already subject to closure by removal under the legislation, including the basins at Cape Fear. N.C.G.S. § 130A-309-214(a)(4). The utility proceeded to describe many aspects of the program suggesting that the closure plans are comprehensive and subject to significant regulatory oversight and public participation. The key assertions are as follows:

• The closure plans, among other things, require the results of a hydrogeologic, geologic, and geotechnical investigation of the site; the results of groundwater modeling of the site; a description of the provisions for disposal of wastewater and management of stormwater; a description of the provisions for the final disposition of the CCR; and a description of the plan for post-closure monitoring and care for an impoundment for a minimum of 30 years.

• The closure plan approval process includes public participation components involving public notice and comment and public meeting(s) in county(ies) in which the site is located. After an opportunity for public comment, NCDEQ makes the final determination as to the protectiveness and adequacy of the closure plan.

The utility goes on to state that NCDEQ's Coal Combustion Residuals Surface Impoundment Closure Guidelines for Protection of Groundwater also sets out robust requirements to establish conformance with the state's closure-by-removal performance standards. Duke Energy notes that the guidelines establish clean-up levels commensurate with site-specific background concentrations. For soil, the clean-up level is either the site-specific background concentration or the lowest soil screening level protective of groundwater. To develop soil remediation goals and corresponding clean-up levels, facility owners or operators must develop an excavation soil sampling plan for each site and submit it to NCDEQ for a determination of whether the plan is sufficient in scope to meet the performance standards for closure. Determinations that CCR removal is complete, according to Duke Energy, rely on a visual confirmation that all CCR and commingled CCR and soil have been removed based on sampling of the material and analysis under polarized light microscopy utilizing American Standards for Testing and Measures D2488, Standard Practice for Description and Identification of Soils (Visual—Manual Procedure).

EPA's independent examination of state CCR programs applicable to legacy units did find that North Carolina's Coal Ash Management Act (CAMA) requires closure of all unlined impoundments, including those at inactive facilities that would qualify as legacy CCR surface impoundments. Further, review of publicly available documentation from Duke Energy, the owner of all currently identified legacy CCR surface impoundments in the state, indicates the presence of state orders-on-consent requiring corrective action for these units. All potential legacy CCR surface impoundments in North Carolina have been or are in the process of closure.

Since publication, several owners and operators of CCR units have provided EPA with additional information they believe demonstrates the adequacy of CCR unit closures performed under the oversight of other regulatory authorities (

e.g.,

state programs). For example, according to Vistra Corp, the Illinois EPA (IEPA) oversaw the closure of a former CCR surface impoundment at the shuttered Havana Power plant. The unit was dewatered and closed in December 1993, under a corrective action plan overseen by IEPA. Surficial water was removed and a three-foot thick cover of soil with vegetation was installed. Groundwater data provided by the utility showed a reduction of boron concentration and compliance with the groundwater standards. At the former Hennepin Power plant in Illinois, another legacy surface impoundment was closed under IEPA oversight. According to Vistra Corp, surficial water was removed, and the unit has been subject to groundwater sampling since 1996. Initial sampling demonstrated exceedances of the boron groundwater standard. In 2020, a final cover system was installed pursuant to the federal CCR rule, consisting of a compacted soil barrier layer with a minimum of 24 inches of earthen material with a maximum permeability of 1 × 10

−7

centimeters per second. The utility states that in limited areas, CCR may be saturated with groundwater during higher flood events of the Illinois River. Vistra Corp contends that the groundwater data demonstrates that simply dewatering and taking this unit offline resulted in significant decreasing trends in boron since 1996, with several wells achieving compliance with the groundwater standard for boron well before the cover system was installed. Further, the utility suggests that the modeling conducted demonstrates that boron concentrations are expected to continue the downward trend even though some ash is saturated with groundwater.

Another utility, Tennessee Valley Authority (TVA), provided EPA with information about Tennessee's CCR program. TVA explained that this information suggests that site-specific human health and ecological risk assessments conducted in the program follow EPA protocols. According to the information provided, the risk assessments have found that there are no unacceptable risks related to CCR management identified for all receptors at most sites. Additionally, the utility stated that potential risk to future workers, where identified, would be mitigated by health and safety protocols. TVA explained that the information provided also speaks to how the state handles closure and corrective action. The state's closure decisions factor in ongoing operations, planned extraction of CCR for beneficial use, risk assessment results, qualitative impacts, and stability assessments. Tennessee's corrective action program incorporates risk assessment results and statistical evaluation of groundwater sampling data to assess regulatory requirements. TVA further explained that no corrective actions have been identified to address unacceptable risks, but localized groundwater corrective actions are required at some units to meet the groundwater protection standards.

The utility also provided specifics about the Tennessee-approved closures at the former John Sevier Fossil Plant. TVA stated that the information speaks to how the state closure and corrective action requirements will control and minimize infiltration, reduce flux from pore water and achieve compliance with groundwater protection standards. Post-closure care requirements are intended to maintain these conditions and the controls in place. The utility contended that the cumulative result is that there will be no unacceptable risks to offsite human or ecological receptors at the facility.

In a third example of relevant information provided to EPA since promulgation of the Legacy Final Rule, Xcel Energy shared details of a

previously conducted closure under the authority of the state of Minnesota. At the Black Dog Plant, the coal-fired generating units ceased operating in April 2015 and disposal of CCR in the onsite units ceased prior to October 19, 2015. The units were certified closed in February 2017. The utility contends that this is an example of a site that was successfully remediated under a rigorous state program and meets acceptable risk criteria. Xcel Energy further states that the quantities of CCR that remain onsite were subject to an extensive site evaluation, risk assessment and the implementation of state-approved remedial action that supported the conclusion that the site is not adversely impacting human health or the environment.

The utility provided documentation of the closure and the state's oversight including the risk assessment conducted, the state-approved remedial action plan, state-approved long-term monitoring plan, and the closure certification. The documentation provided suggests that, in total, the closure involved the removal of 117,300 cubic yards of CCR and impacted soils and the import of 717,000 cubic yards of clean fill material. At the ponds where removal of all non-native materials (including CCR) wasn't conducted, a 4-foot cap of clean imported fill material was utilized. Additionally, groundwater monitoring was conducted before and after the remedial action. The site now features a bike path along the Minnesota River.

EPA intends to maintain the general procedures in the existing regulations, whereby owners and operators of legacy surface impoundments may defer compliance with the CCR unit closure standards until a site-specific decision is made by the permit authority on the equivalence of the previously conducted closures. However, based on the information above as well as the considerations discussed in Unit III.D. regarding the benefit of regulatory oversight (

i.e.,

allowing a permit authority to evaluate risk and determine requirements based on site-specific considerations), the new tools provided to EPA as part of the WIIN Act, and the ability of EPA to allow for non-uniformity in attainment of the baseline RCRA standard of protection, EPA is proposing to modify § 257.101(g) to expand the deferral criteria. Specifically, EPA proposes to adjust the deferral criteria by removing three of the standards that currently must be met to be eligible for the deferral. EPA is proposing to remove: (1) The detailed technical requirements for a groundwater monitoring system, (2) The requirement that a facility document that the legacy CCR surface impoundment currently meets either the location standard in § 257.60 or the dewatering standard in § 257.102(d)(1)(i), and (3) The requirement that the regulatory authority conducted a site-specific risk assessment. EPA is instead proposing that the owner or operator would need to document that a regulatory authority played an active role in overseeing and approving the closure and any necessary corrective action, pursuant to an enforceable requirement issued on or after October 19, 2015, a groundwater monitoring system was installed, and groundwater monitoring was performed. The owner or operator would need to also provide the same certification as to the veracity of the documentation currently required under § 257.101(g)(5).

EPA anticipates that this amendment will lead to an increase in the number of closed legacy impoundments eligible for deferral. As a result, fewer legacy surface impoundments will be required to undertake additional closure activities before the CCR permit authority determines that such actions are indeed necessary. It is worth noting that all legacy surface impoundments eligible for the deferral would still, at the time of permitting, be required to submit a permit application with sufficient information, including groundwater data, to demonstrate the applicable closure standards had been met. In the meantime, the unit would be subject to groundwater monitoring and corrective action in the event any problems are identified that require remedial action. The CCR permit authority would then make a final determination as to whether the previously conducted closure achieved the applicable performance standards established in the Federal CCR regulations.

The proposed amendment ensures that previous decisions made by state or federal regulators remain unaffected until the CCR permitting program can conduct site-specific evaluations. This approach allows for greater continuity in the short term and ensures EPA does not require compliance with additional subtitle D requirements that may not result in benefits to human health or the environment unless and until it is determined that additional closure activities are indeed necessary. Furthermore, this change allows for greater implementation resources to be directed to site-specific permitting to address risks and away from evaluating compliance with a more complex set of deferral criteria. Finally, adding this flexibility comes with relatively little tradeoff. Most of these legacy CCR surface impoundments have been in place for decades. More recently, these units were closed under the oversight of a regulatory authority and now have controls in place to reduce risk. Delaying potential compliance with the federal closure requirement for a comparatively short period of time until a site-specific examination of the units and their completed closure can be completed by a permit authority is unlikely to significantly change the environmental conditions or risks at these facilities. The risk associated with the deferral is further attenuated by the ongoing requirement for groundwater monitoring and corrective action. While the units were already closed once under the oversight of a state or other authority and so environmental controls may be in place, if the unit contaminates groundwater, the groundwater monitoring system would identify it. The corrective action requirements would then require remediation to ensure no adverse effects to health and the environment.

At the time of permitting, the permitting authority would evaluate the unit more closely—with the benefit of site-specific information—to determine the “equivalence” of closure conducted under the state or alternate authority. EPA is not proposing to revise this process established under § 257.101(g)(6). At this stage, additional closure and/or post-closure requirements may be imposed by the permitting authority to achieve compliance with the Part 257 regulations including the closure performance standard. As such, the unit will ultimately achieve compliance with the Federal closure performance standard—just under the oversight of a permitting authority, rather than under a self-implementing framework.

Therefore, EPA is proposing that owners or operators of legacy CCR surface impoundments that have completed a closure prior to November 8, 2024, where a regulatory authority played an active role in overseeing and approving the closure and any necessary corrective action, pursuant to an enforceable requirement issued on or after October 19, 2015; a groundwater monitoring system has been installed; and groundwater monitoring has been performed would be eligible to defer compliance with the applicable closure performance standard until permitting. The owner or operator would need to document they meet the criteria in an owner-or-operator certified report. EPA is proposing to require this documentation be completed within six months of the effective date of the rule,

if finalized. This compliance timeframe was used for the original deferral certification at § 257.101(g). EPA expects this will provide ample time for the owners and operators to prepare the necessary documentation.

Solicitation of comment.

EPA is also soliciting comments on an alternative to this proposal that would allow owners and operators of legacy surface impoundments to defer compliance with the closure performance standard until the CCR permit authority can make a site-specific determination regarding the 'equivalence' of the previously conducted closure. Specifically, EPA is soliciting comment on potential changes to § 257.101(g) to expand the deferral criteria for legacy CCR surface impoundments to owners and operators that completed closure of the unit under state or federal regulatory authority prior to November 8, 2024, where a regulatory authority played an active role in overseeing and approving the closure and any necessary corrective action, pursuant to an enforceable requirement issued on or after October 19, 2015. In this alternative, installation and operation of a groundwater monitoring system would not be required for an owner or operator to avail themselves of the deferral. This alternative approach would solely require that the owner or operator document that the closure of the unit, and any necessary corrective action, was actively overseen by a regulatory authority to qualify for the deferral. However, under this alternative, the same information as required under the proposed option would be required at the time of permitting.

EPA expects this option would allow a greater number of additional units to qualify for the deferral than the proposed approach. Similar to the proposed approach, all units for which closure decisions were deferred to permitting, would be required to comply with the groundwater monitoring, corrective action, and any applicable post-closure requirements at least until a permit authority permits the unit. The advantages of this alternative approach are the same as for the proposed approach but would likely be realized at a greater number of units. Much like the proposed approach, this alternative approach would ensure that previous decisions made by State or Federal regulators remain unaffected until the CCR permitting program can conduct site-specific evaluations. This alternative approach would also allow for greater continuity in the short term and would ensure EPA does not require compliance with additional subtitle D requirements that may not result in benefits to human health or the environment unless and until it is determined that additional closure activities are indeed necessary.

The disadvantage of this approach, relative to the proposed approach, is that it may result in delays and a greater burden on the CCR permit authority to determine the protectiveness of the completed closure without historic groundwater monitoring data for the units in question. Additionally, deferring compliance with the existing closure performance standards at a greater number of units until permitting, may result in a greater potential for adverse effects on human health or the environment in the interim at a greater number of facilities. Those potential impacts may be exacerbated by delays in permitting if more closure “equivalency” determinations are deferred to permitting and there isn't sufficient groundwater monitoring data to evaluate the protectiveness of the completed closures in a timely manner.

However, as noted and described above, EPA received information during the Legacy Rule development and since finalization from utilities and trade groups arguing that CCR unit closures performed under the oversight of other regulatory authorities (

e.g.,

state programs) are adequate. This information includes several examples of unit specific closures with oversight from state or other regulatory programs. Additionally, the descriptions of the regulatory programs provided to EPA note that risk assessments were conducted, the regulatory authorities conducted a variety of oversight activities, and groundwater monitoring and corrective action were required to help ensure the closures remain protective. Moreover, it's worth noting that these units would still be subject to the groundwater monitoring, closure and any necessary corrective action and post-closure care requirements. See § 257.100(f). As such, EPA is taking comment on this alternative approach and, if supported by sufficient factual comments, may finalize this approach.

If EPA were to finalize this approach, EPA would amend the criteria for deferral in § 257.101(g) to consist only of documentation that a regulatory authority played an active role in overseeing and approving the closure and any necessary corrective action, pursuant to an enforceable requirement, and the certification as to the veracity of the information. Specifically, EPA would remove the existing criteria in § 257.101(g)(2) through (4). The process for the CCR permitting program to make the “equivalence” determination or establish additional requirements for the legacy impoundment would remain unchanged.

Additionally, due to the practical limitations and inherent uncertainty related to the record, EPA requests comment on the adequacy of the record for the proposal and the alternative option upon which EPA is soliciting comment and, to the extent any gaps are identified, requests suggestions for sources of additional information. As described above, during the rulemaking for the Legacy Rule, the Agency had received information to demonstrate that previous closure decisions made under state or other regulatory authorities will protect human health and the environment. Since promulgation of the Legacy Final Rule, the Agency received additional information describing a handful of state programs and several individual, site-specific closure decisions. In acknowledgement of the additional information received, and to realize the benefits described above, this proposal offers greater deference to the state and other regulatory authorities that made these closure decisions previously. EPA expects that those authorities would not have approved of closures that presented a reasonable probability of adverse effects to human health and the environment.

However, the Agency lacks a record that unequivocally demonstrates that all closure decisions made by other regulatory programs will be similarly protective—in the near term—as applying the Federal CCR closure requirements immediately. Such a record would consist of a detailed review of all state CCR programs as well as other relevant regulatory programs that may have overseen legacy CCR unit closures. This review would need to provide a detailed understanding of the programs at the points in time the relevant closure decisions had been made. At present, EPA has information on a handful of state programs and several site-specific closure decisions. While meaningful, this information doesn't speak to every previous closure decision that had been made. For example, even for closures conducted under voluntary programs, the level of oversight of those programs may vary between states. In some states, the voluntary closure may entail significant oversight, (

e.g.,

regulator review and approval of the closure and groundwater monitoring plans, review of groundwater monitoring data) but not necessarily in all states. EPA will consider such information submitted as it develops the final action.

3. CCR Management Units

In the Legacy Final Rule, EPA established requirements to address the risks from exempt solid waste management that involves the direct placement of CCR on the land. EPA extended a subset of the existing requirements in 40 CFR part 257, subpart D to these units, which are CCR surface impoundments and landfills that closed prior to the effective date of the 2015 CCR Rule, inactive CCR landfills, and other areas where CCR is managed directly on the land. These additional requirements apply to all active CCR facilities, all inactive facilities with legacy CCR surface impoundments, and those active facilities (

i.e.,

facilities producing electricity for the grid as of October 19, 2015) that ceased placing CCR in onsite CCR units prior to the effective date of the 2015 CCR Rule (“other active facilities”).

In the preamble to the Legacy Final Rule, EPA discussed the rationale of the definition of “CCR management unit” and the scope of what would be considered a CCRMU under the final rule. See 89 FR 39044-39051. EPA finalized this definition based on damage cases, the 2024 risk assessment, and comments received on the Legacy Proposed Rule. Many of the Legacy Proposed Rule comments argued that the definition of CCRMU is overly broad and treats many different disposal areas as a worse-case scenario. Commenters further stated that the scope of the CCRMU universe ignores the risk profiles of different historic disposal areas and forces actions not tailored to the specific units. The comments also said a one-size-fits-all approach to CCRMU does not make sense given the widely variable risk profiles within this newly defined category of regulated units.

In 2025, EPA received several letters from the regulated community, including a coalition of regulated entities,

USWAG,

National Rural Electric Cooperative Association (NRECA),

Cross-Cutting Issues Group (CCIG),

Edison Electric Institute (EEI),

American Electric Power (AEP),

PacifiCorp,

Talen Energy via the National Energy Dominance Council,

and others that recommended changes to the CCRMU requirements. The letters suggested these changes were supported by several critiques of the Legacy Final Rule and the 2024 Risk Assessment, and recent Executive Orders, including “Reinvigorating America's Beautiful Clean Coal Industry and Amending Executive Order 14241” (April 8, 2025).

Duke Energy et al 2025. Letter co-signed by Duke Energy, Vistra Corp, Lower Colorado River Authority, City Utilities of Springfield, Southern Illinois Power Cooperative, Gavin Power, Talen Energy, Basin Electric Power Cooperative, Ohio Valley Electric Corporation, Indiana-Kentucky Electric Corporation, and Louisville Gas and Electric Company-Kentucky Utilities Energy to Lee Zeldin, EPA Administrator. RE: Coal Combustion Residuals Rules Impede U.S. Energy Production. January.

USWAG 2025a. Letter from Daniel L. Chartier, Executive Director, Utility Solid Waste Activities Group to Lee Zeldin, EPA Administrator. Re: Actions for Regulations for CCR. January.

NRECA 2025. Letter from Jim Matheson, Chief Executive Officer, National Rural Electric Cooperative Association to Lee Zeldin, EPA Administrator. January.

CCIG 2025. White paper reflecting Recommendations Updating the Federal CCR Regulations. Cross-Cutting Issues Group. June.

EEI 2025a. Comments on Site-Specific Closure Alternative Performance Standard. Edison Electric Institute. June.

AEP 2025. Meeting handout to EPA's Office of Land and Emergency Management. American Electric Power. RE: Legacy CCR Rule Reform Regulations. June.

PacifiCorp 2025. Letter from James Owen, Vice President of Environmental and Energy Resources, PacifiCorp to EPA Region 8. RE: PacifiCorp Priorities in EPA Region 8 States. April.

NEDC 2025. Comments from NEDC with CCR Reform Guiding Principles. National Energy Dominance Council. August.

In many letters, the authors recommended rescinding the CCRMU provisions. In other letters, regulated entities recommend that EPA narrow the scope of CCRMU provisions and clarify certain requirements. Some commenters recommended that EPA: (1) Eliminate the requirement to identify CCRMU containing less than 1,000 tons of CCR; (2) Increase the CCRMU deferral threshold from 1,000 tons to an alternative quantity associated with acceptable beneficial use or to risk-based criteria for stability, groundwater, and dust; (3) Exempt past beneficial use placements and critical infrastructure sites; (4) Exempt areas of CCR accumulation regulated by State agencies, including units closed in accordance with State programs; (5) Establish a baseline to identify potential CCRMU (

e.g.,

facilities operating after a certain date); (6) Establish options to exempt areas listed in the Facility Evaluation Report (FER) as a CCRMU if the CCR material is removed from that area within a specified time period (

e.g.,

an area is exempt if the CCR is removed with one year of the FER Part 2 being published; and (7) Limit the CCRMU definition to past placements that pose identified present risks.

In response to the information presented in the above letters and based on the limitations of a national risk assessment, including the 2024 Risk Assessment, as discussed in Unit III.D. of this preamble, EPA is proposing to rescind all CCRMU requirements. In the alternative, EPA is soliciting comments on several potential revisions to the existing CCRMU regulations. Each of these potential revisions is intended to address one or more of the issues discussed above. Although the potential revisions are not intended to be mutually exclusive (

i.e.,

EPA may adopt several of them in the final rule), a single revision may address multiple issues. Consequently, it may not be necessary to adopt all the potential revisions to address all the issues that have been raised to the Agency. EPA therefore requests comment on whether all the various revisions discussed in Unit IV.A.3.b. of this preamble are necessary or useful. Commenters are encouraged to consider the combined effect of individual revisions in developing their comments. EPA also requests that, if commenters believe that individual alternatives would address the same issue, they provide views on whether (and why) one alternative is preferable.

Lastly, given that EPA may adopt one or more of the options discussed in Unit IV.A.3.b. of this preamble, EPA solicits comments on the appropriate scope of the FER given the commenter's preferred option(s). As explained in Unit III.C. of this preamble, the FER Part 1 documents the thorough review of readily and reasonably available records regarding where CCR was either routinely and systematically placed on land, or where facility activities otherwise resulted in measurable accumulations of CCR on land. The FER Part 2 documents the conclusions of a physical evaluation of the facility to address any data and information gaps identified in FER Part 1. Together, the FER Parts 1 and 2 are intended to provide a complete picture of the historic use, placement and the status of CCR at the facility, ultimately identifying any CCRMU of 1 ton or greater onsite. The FER Part 1 requirements regarding record review were based off EPA's understanding of what documentation would potentially hold information about historic placements that would meet the definition of CCRMU. However, EPA acknowledges that if the scope of the CCRMU universe is modified, the FER requirements, specifically with respect to review of readily and reasonably available records regarding where CCR was either routinely and systematically placed on land, or where facility activities otherwise resulted in measurable accumulations of CCR on land, may warrant modification too. Therefore, EPA solicits comment on the

appropriate scope of the FER requirements as they are impacted by the options described below.

a. Rescind All CCR Management Unit Requirements

In response to the letters and requests that EPA has received since January 2025 and based on the limitations of a national risk assessment, including the 2024 Risk Assessment, as described in Unit III.D. of this preamble, EPA is reconsidering its decisions to regulate CCRMU. As stated above in Units III.D. and IV.A.3. of this preamble, EPA received questions about the risk assessment and other comments after the publication of the Legacy Final Rule that said the definition of CCRMU is overly broad.

Some of the information EPA received after publication of the 2024 Legacy Rule suggests that EPA should rescind the CCRMU requirements and is intended to show the infeasibility of the CCRMU requirements. CCIG provided specific examples of this infeasibility in their letter dated June 6, 2025,

including rail embankments or railroad roadbed constructed with CCR components that would pose logistical challenges for groundwater monitoring, CCR used as drainage layers above composite liners, CCR used in embankments, CCR used to construct over 10 miles of road at the facility, previously closed surface impoundments below plant infrastructure, an active landfill on top of a previously closed unit, CCRMU under a natural gas pipeline, CCR used as fill for the construction of the facility that processes and encapsulates CCR for beneficial use, and units that were near closure but would be considered CCRMU. CCIG also said that requiring the removal and replacement of the wide range of uses of CCR that fall under the broad CCRMU definition, including those described above, will end up causing cascading issues that potentially could impact reliability, force the use of virgin resources, and impose burdensome, unnecessary costs on energy companies and their customers. Therefore, based on the reasons above CCIG recommended EPA rescind the CCRMU requirements. Other commenters stated that rescinding the CCRMU provisions was justified as the court in the 2018

USWAG

decision only required regulation of legacy CCR surface impoundment and not CCRMU. Many of these letters also state that CCRMU should be “eliminated” because: (1) The record has not been fully developed to support regulating CCRMU, and (2) Significant compliance costs outweigh any potential benefits to address unproven risks. Several of the entities also claim the CCRMU regulations impose infeasible, impracticable, and overly burdensome requirements on energy companies with significant costs that would eventually be placed on consumers.

CCIG 2025. White paper reflecting Recommendations Updating the Federal CCR Regulations. Cross-Cutting Issues Group. June.

Other letters stated that EPA's 2024 Risk Assessment does not support the overly broad CCRMU definition or demonstrate that all CCRMU pose a reasonable probability of adverse effects on health or the environment. The letters noted that the national risk assessment was based on high-end risks and did not accurate capture the variability of risk posed by units at many facilities. The authors conclude that EPA's Risk Assessments systematically overstate the risk from CCR disposal units and fills, and that it would be more effective and appropriate to assess risks on a site-specific basis. Furthermore, the commenters state that EPA did not justify the CCRMU regulations through a proper risk assessment.

As explained in Unit III.D. of this preamble, EPA uses a national risk assessment for a particular source or industry category to inform its decision concerning whether a regulatory program is needed or in need of revisions. Both the 2014 and 2024 Risk Assessments were designed to capture the full spectrum of potential disposal scenarios across the country with available data and decisions about the need for national regulations were based on high-end risks identified from across these scenarios, considered together with proven damage cases, to ensure that regulations would be consistently protective. The Agency acknowledges that these high-end risks may not manifest at every site and concurs that risks associated with individual CCR units may be lower. This is equally true for disposal units, fills, piles, and unencapsulated accumulations on the land for any other stated purpose.

In addition, EPA is proposing to find the current definition of CCRMU is overly broad, capturing units that under this proposal would not involve “disposal.” Specifically, EPA's proposed changes affecting beneficial use and storage of CCR would result in the existing definition of CCRMU encompassing some units that do not involve “disposal” as defined § 257.53. As explained in more detail in Unit IV.C., EPA is proposing to revise the definition of beneficial use to eliminate the distinction between on-site and off-site activities, and to eliminate the definition of a CCR pile. If those proposals are adopted, the current definition of a CCRMU as “area of land on which any noncontainerized accumulation of CCR is received, is placed, or is otherwise managed,” would also capture CCR storage units and beneficial use projects (other than roadbed and associated embankments, which are explicitly excluded from the definition) and consequently would not involve the disposal of CCR. See definition of “disposal” in § 257.53, which states “For purposes of this subpart, disposal does not include the storage or the beneficial use of CCR.”

EPA acknowledges that this is a change in position from previous statements in the 2024 CCR Legacy Rule, which stated that direct placement of CCR on the land onsite of a utility, with nothing to control releases is, by definition, a CCR pile and therefore not beneficial use (while, in contrast, CCR that is beneficially used

off-site

is not a CCR pile), and then further referenced statements from the 2015 CCR Rule that CCR piles constitute disposal and are consequently subject to all regulatory criteria applicable to CCR landfills. (89 FR 39050).

However, as explained in more detail in Unit IV.C., EPA's proposed revisions would ensure consistency and clarity across all settings in accurately identifying which practices are beneficial use or storage, and not disposal.

Finally, EPA finds that the existing definition of CCRMU runs afoul of several recent executive orders: Executive Order 14154 “Unleashing American Energy,” 90 FR 8343 (January 29, 2025); Executive Order 14156 “Declaring a National Energy Emergency,” 90 FR 8433 (January 30, 2025); and Executive Order 14219 “Ensuring Lawful Governance and Implementing the President's `Department of Government Efficiency' Deregulatory Initiative,” 90 FR 10583 (February 25, 2025). EPA is proposing to rescind the CCRMU provisions consistent with those directives.

Therefore, based on the information above, along with the conclusions stated in Unit III.D. of this preamble, EPA is proposing to remove the CCRMU regulations from 40 CFR part 257, subpart D. In particular, EPA is proposing to amend or remove the following regulatory text sections, such that CCRMU are no longer units regulated under 40 CFR part 257: §§ 257.50(d); 257.53: definitions of “CCR management unit”, portion of “CCR unit”, “Closed prior to October 19, 2015”, “Critical infrastructure”,

“Inactive CCR landfill”, and “Regulated CCR unit”; 257.75; 257.90(b)(3); a sentence from 257.90(e); change 257.95(b) back to 2015 CCR Rule language; references to CCRMU in 257.100(h)(2); 257.101(f); portions of 257.101(g); 257.101(h); title of 257.102; 257.102(b)(2)(iii) and (v) and renumber (iv) to (iii); 257.102(f)(1)(iii); 257.100(f)(2)(ii)(E) and (F), 257.104(d)(2)(iii); 257.105(f)(25) and (26); 257.106(f)(24) and (25); 257.107(f)(24) and (25).

b. Alternative Approaches for Comment

As stated above, EPA is soliciting comment on several alternative approaches to address the concerns laid out in Units III.D. and IV.A.3. of this preamble regarding the CCRMU regulations. Specifically, EPA is soliciting comment on: (1) Deferring all CCRMU requirements, other than the requirement to complete the facility evaluation, to permitting; (2) Establishing groundwater monitoring and corrective action zones for CCRMU; (3) Exempting past onsite CCR uses that meet the definition of beneficial use; (4) Expanding the roadbed exemption; (5) Expanding the deferral criteria for certain CCRMU closures to permitting; (6) Removing “other active facilities” from the regulated universe; and (7) Developing a new threshold for CCRMU. EPA will consider comments on the proposal and all these options before making a final decision. If EPA elects to not rescind all regulation of CCRMU, EPA may select one or several of the options to finalize. For example, EPA may choose to only finalize the option to defer all CCRMU requirements aside from the facility evaluation to permitting. Alternatively, EPA may choose to finalize the options to defer all CCRMU requirements aside from the facility evaluation to permitting, expand the roadbed exemption, and exempt past onsite CCR uses that meet the definition of beneficial use. If EPA were to finalize this combination of options, the result would be a much smaller CCRMU universe consisting primarily of inactive landfills and units closed prior to 2015, which would only be subject to the facility evaluation requirements in § 257.75 until such time that the permit authority could evaluate these units. Since EPA is soliciting comment on several other alternative approaches to amending the scope of the CCRMU universe, EPA is not including these regulatory changes in the proposed regulatory text in this rule, as it could cause confusion for the reader. However, EPA will describe the regulatory text changes these alternative approaches would have if finalized in the preamble below. EPA requests comment on the proposed regulatory text changes as well as these alternatives, as well as how EPA should revise the FER requirements considering the alternatives below.

i. Deferral of CCR Management Unit Requirements To Permitting

EPA is taking comment on an alternative approach to addressing the issues identified in Units III.D. and IV.A.3. of this preamble with the existing CCRMU regulation. Under this alternative approach, owners or operators of regulated CCR units would still be required to complete the two-part FER to identify and delineate CCRMU at the facility. However, the requirement to comply with the remaining CCRMU regulations would be deferred until a CCR permit authority is able to evaluate the risks posed by these units and determine which requirements are appropriate for the CCRMU. Essentially, under this alternative approach, all CCRMU would be treated the same as CCRMU containing between 1 and 1,000 tons are treated under the existing regulations.

In the Legacy Final Rule, EPA finalized facility evaluation, fugitive dust, groundwater monitoring, corrective action, closure, and post-closure care requirements for CCRMU. As a result of the Legacy Final Rule, owners or operators of regulated CCR units are required to conduc

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