# Hazardous and Solid Waste Management System; Identification and Listing of Special Wastes; Disposal of Coal Combustion Residuals From Electric Utilities

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URL: https://www.frixlaw.com/law-library/documents/fr%3A2010-12286

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** June 21, 2010
- **Citation:** 75 FR 35128

## Text

ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 257, 261, 264, 265, 268, 271 and 302
[EPA-HQ-RCRA-2009-0640; FRL-9149-4]
RIN-2050-AE81
Hazardous and Solid Waste Management System; Identification and Listing of Special Wastes; Disposal of Coal Combustion Residuals From Electric Utilities

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA or Agency) is proposing to regulate for the first time, coal combustion residuals (CCRs) under the Resource Conservation and Recovery Act (RCRA) to address the risks from the disposal of CCRs generated from the combustion of coal at electric utilities and independent power producers. However, the Agency is considering two options in this proposal and, thus, is proposing two alternative regulations. Under the first proposal, EPA would reverse its August 1993 and May 2000 Bevill Regulatory Determinations regarding coal combustion residuals (CCRs) and list these residuals as special wastes subject to regulation under subtitle C of RCRA, when they are destined for disposal in landfills or surface impoundments. Under the second proposal, EPA would leave the Bevill determination in place and regulate disposal of such materials under subtitle D of RCRA by issuing national minimum criteria. Under both alternatives EPA is proposing to establish dam safety requirements to address the structural integrity of surface impoundments to prevent catastrophic releases.

EPA is not proposing to change the May 2000 Regulatory Determination for beneficially used CCRs, which are currently exempt from the hazardous waste regulations under Section 3001(b)(3)(A) of RCRA. However, EPA is clarifying this determination and seeking comment on potential refinements for certain beneficial uses. EPA is also not proposing to address the placement of CCRs in mines, or non-minefill uses of CCRs at coal mine sites in this action.

DATES:

Comments must be received on or before September 20, 2010. EPA will provide an opportunity for a public hearing on the rule upon request. Requests for a public meeting should be submitted to EPA's Office of Resource Conservation and Recovery by July 21, 2010.
See
the
FOR FURTHER INFORMATION CONTACT
section for contact information. Should EPA receive requests for public meetings within this timeframe, EPA will publish a document in the
Federal Register
providing the details of such meetings.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-HQ-RCRA-2009-0640, by one of the following methods:

•
http://www.regulations.gov:
Follow the on-line instructions for submitting comments.

•
E-mail:
Comments may be sent by electronic mail (e-mail) to
rcra-docket@epa.gov,
Attention Docket ID No. EPA-HQ-RCRA-2009-0640. In contrast to EPA's electronic public docket, EPA's e-mail system is not an “anonymous access” system. If you send an e-mail comment directly to the Docket without going through EPA's electronic public docket, EPA's e-mail system automatically captures your e-mail address. E-mail addresses that are automatically captured by EPA's e-mail system are included as part of the comment that is placed in the official public docket, and made available in EPA's electronic public docket.

•
Fax:
Comments may be faxed to 202-566-0272; Attention Docket ID No. EPA-HQ-RCRA-2009-0640.

•
Mail:
Send your comments to the Hazardous Waste Management System; Identification and Listing of Special Wastes; Disposal of Coal Combustion Residuals From Electric Utilities Docket, Attention Docket ID No., EPA-HQ-RCRA-2009-0640, Environmental Protection Agency,
Mailcode:
5305T, 1200 Pennsylvania Ave., NW., Washington, DC 20460. Please include a total of two copies.

•
Hand Delivery:
Deliver two copies of your comments to the Hazardous Waste Management System; Identification and Listing of Special Wastes; Disposal of Coal Combustion Residuals From Electric Utilities Docket, Attention Docket ID No., EPA-HQ-RCRA-2009-0640, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC 20460. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions:
Direct your comments to Docket ID No. EPA-HQ-RCRA-2009-0640. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at
http://www.regulations.gov,
including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through
http://www.regulations.gov
or e-mail. The
http://www.regulations.gov
Web site is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through
http://www.regulations.gov,
your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket, visit the EPA Docket Center homepage at
http://www.epa.gov/epahome/dockets.htm.
For additional instructions on submitting comments, go to the
SUPPLEMENTARY INFORMATION
section of this document.

Docket:
All documents in the docket are listed in the
http://www.regulations.gov
index. Although listed in the index, some information is not publicly available,
e.g.,
CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in
http://www.regulations.gov
or in hard copy at the Hazardous Waste Management System; Identification and Listing of Special Wastes; Disposal of Coal Combustion Residuals From Electric Utilities Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC 20460. This Docket Facility is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The Docket telephone number is (202) 566-0270. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The

telephone number for the Public Reading Room is (202) 566-1744.

FOR FURTHER INFORMATION CONTACT:

Alexander Livnat, Office of Resource Conservation and Recovery, Environmental Protection Agency, 5304P;
telephone number:
(703) 308-7251;
fax number:
(703) 605-0595;
e-mail address: livnat.alexander@epa.gov,
or Steve Souders, Office of Resource Conservation and Recovery, Environmental Protection Agency, 5304P;
telephone number:
(703) 308-8431;
fax number:
(703) 605-0595;
e-mail address: souders.steve@epa.gov.
For technical information on the CERCLA aspects of this rule, contact Lynn Beasley, Office of Emergency Management, Regulation and Policy Development Division (5104A), U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, NW., Washington, DC 20460, [
E-mail address and telephone number: Beasley.lynn@epa.gov
(202-564-1965).]

For more information on this rulemaking please visit
http://www.epa.gov/epawaste/nonhaz/industrial/special/fossil/index.htm.

SUPPLEMENTARY INFORMATION:

A. Does this action apply to me?

The proposed rule would apply to all coal combustion residuals (CCRs) generated by electric utilities and independent power producers. However, this proposed rule does not address the placement of CCRs in minefills. The U. S. Department of Interior (DOI) and EPA will address the management of CCRs in minefills in a separate regulatory action(s), consistent with the approach recommended by the National Academy of Sciences, recognizing the expertise of DOI's Office of Surface Mining Reclamation and Enforcement in this area.
1

In addition, under either alternative proposal, EPA is not proposing to affect the current status of coal combustion residuals that are beneficially used.
2

(
See
section IV. D for further details on proposed clarifications of beneficial use.) CCRs from non-utility boilers burning coal are not included within today's proposed rule. EPA will decide on an appropriate action for these wastes after completing this rulemaking effort.

1
The National Research Council (NRC) Committee on Mine Placement of Coal Combustion Wastes stated: “The committee believes that OSM and its SMCRA state partners should take the lead in developing new national standards for CCR use in mines because the framework is in place to deal with mine-related issues.” National Academy of Sciences. Managing Coal Combustion Residues in Mines; The National Academies Press, Washington, DC, 2006.

2
The NRC committee recommended “that secondary uses of CCRs that pose minimal risks to human health and the environment be strongly encouraged.”
Ibid.

The proposed rule may affect the following entities: electric utility facilities and independent power producers that fall under the North American Industry Classification System (NAICS) code 221112, and hazardous waste treatment and disposal facilities that fall under NAICS code 562211. The industry sector(s) identified above may not be exhaustive; other types of entities not listed could also be affected. The Agency's aim is to provide a guide for readers regarding those entities that potentially could be affected by this action. To determine whether your facility, company, business, organization, etc., is affected by this action, you should refer to the applicability criteria contained in section IV of this preamble. If you have any questions regarding the applicability of this action to a particular entity, consult the person listed in the preceding
FOR FURTHER INFORMATION CONTACT
section.

B. What should I consider as I prepare my comments for EPA?

1.
Submitting confidential business information (CBI).
Do not submit information that you consider to be CBI through
http://www.regulations.gov
or by e-mail. Send or deliver information identified as CBI only to the following address: RCRA CBI Document Control Officer, Office of Resource Conservation and Recovery (5305P), U.S. EPA, 1200 Pennsylvania Avenue, NW., Washington DC 20460, Attention Docket No, EPA-HQ-RCRA-2009-0640. You may claim information that you submit to EPA as CBI by marking any part or all of the information as CBI (if you submit CBI on a disk or CD ROM, mark the outside of the disk or CD ROM as CBI and then identify electronically within the disk or CD ROM the specific information that is claimed as CBI). Information so marked will not be disclosed, except in accordance with the procedures set forth in 40 CFR part 2. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. If you submit the copy that does not contain CBI on disk or CD ROM, mark the outside of the disk or CD ROM clearly that it does not contain CBI. Information not marked as CBI will be included in the public docket and EPA's electronic public docket without prior notice. If you have questions about CBI or the procedures for claiming CBI, please contact: LaShan Haynes, Office of Resource Conservation and Recovery (5305P), U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, NW., Washington DC 20460-0002, telephone (703) 605-0516, e-mail address
haynes.lashan@epa.gov.

2
. Tips for Preparing Your Comments.
When submitting comments, remember to:

• Identify the rulemaking by docket number and other identifying information (subject heading,
Federal Register
date and page number).

• Follow directions—The Agency may ask you to respond to specific questions or organize comments by referencing a Code of Federal Regulations (CFR) part or section number.

• Explain why you agree or disagree, suggest alternatives, and substitute language for your requested changes, and explain your interest in the issue you are attempting to address.

• Describe any assumptions and provide any technical information and/or data that you used.

• If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced.

• Provide specific examples to illustrate your concerns, and suggest alternatives.

• Explain your views as clearly as possible.

• Make sure to submit your comments by the comment period deadline identified.

3.
Docket Copying Costs.
The first 100-copied pages are free. Thereafter, the charge for making copies of Docket materials is 15 cents per page.

C. Definitions, Abbreviations and Acronyms Used in This Preamble (
Note:
Any term used in this proposed rulemaking that is not defined in this section will either have its normal dictionary meaning, or is defined in 40 CFR 260.10.)

Acre-foot
means the volume of one acre of surface area to a depth of one foot.

Beneficial Use of Coal Combustion Products (CCPs)
means the use of CCPs that provides a functional benefit; replaces the use of an alternative material, conserving natural resources that would otherwise need to be obtained through practices such as extraction; and meets relevant product specifications and regulatory standards (where these are available). CCPs that are used in excess quantities (
e.g.,
the field-applications of FGD gypsum in amounts that exceed scientifically-supported quantities required for enhancing soil properties and/or crop

yields), placed as fill in sand and gravel pits, or used in large scale fill projects, such as for restructuring the landscape, are excluded from this definition.

Boiler slag
means the molten bottom ash collected at the base of slag tap and cyclone type furnaces that is quenched with water. It is made up of hard, black, angular particles that have a smooth, glassy appearance.

Bottom ash
means the agglomerated, angular ash particles, formed in pulverized coal furnaces that are too large to be carried in the flue gases and collect on the furnace walls or fall through open grates to an ash hopper at the bottom of the furnace.

CCR Landfill
means a disposal facility or part of a facility where CCRs are placed in or on land and which is not a land treatment facility, a surface impoundment, an underground injection well, a salt dome formation, a salt bed formation, an underground mine, a cave, or a corrective action management unit. For purposes of this proposed rule, landfills also include piles, sand and gravel pits, quarries, and/or large scale fill operations. Sites that are excavated so that more coal ash can be used as fill are also considered CCR landfills.

CCR Surface Impoundment
or
impoundment
means a facility or part of a facility which is a natural topographic depression, man-made excavation, or diked area formed primarily of earthen materials (although it may be lined with man-made materials), which is designed to hold an accumulation of CCRs containing free liquids, and which is not an injection well. Examples of CCR surface impoundments are holding, storage, settling, and aeration pits, ponds, and lagoons. CCR surface impoundments are used to receive CCRs that have been sluiced (flushed or mixed with water to facilitate movement), or wastes from wet air pollution control devices, often in addition to other solid wastes.

Cenospheres
are lightweight, inert, hollow spheres comprised largely of silica and alumina glass.

Coal Combustion Products (CCPs)
means fly ash, bottom ash, boiler slag, or flue gas desulfurization materials, that are beneficially used.

Coal Combustion Residuals (CCRs)
means fly ash, bottom ash, boiler slag, and flue gas desulfurization materials destined for disposal. CCRs are also known as coal combustion wastes (CCWs) and fossil fuel combustion (FFC) wastes, when destined for disposal.

Electric Power Sector (Electric Utilities and Independent Power Producers)
means that sector of the power generating industry that comprises electricity-only and combined-heat-and-power (CHP) plants whose primary business is to sell electricity, or electricity and heat, to the public.

Existing CCR Landfill
means a landfill which was in operation or for which construction commenced prior to the effective date of the final rule. A CCR landfill has commenced construction if the owner or operator has obtained the Federal, State and local approvals or permits necessary to begin physical construction; and either

(1) A continuous on-site, physical construction program has begun; or

(2) The owner or operator has entered into contractual obligations—which cannot be cancelled or modified without substantial loss—for physical construction of the CCR landfill to be completed within a reasonable time.

Existing CCR Surface Impoundment
means a surface impoundment which was in operation or for which construction commenced prior to the effective date of the final rule. A CCR surface impoundment has commenced construction if the owner or operator has obtained the Federal, State and local approvals or permits necessary to begin physical construction; and either

(1) A continuous on-site, physical construction program has begun; or

(2) The owner or operator has entered into contractual obligations—which can not be cancelled or modified without substantial loss—for physical construction of the CCR surface impoundment to be completed within a reasonable time.

Flue Gas Desulfurization (FGD)
material means the material produced through a process used to reduce sulfur dioxide (SO
2
) emissions from the exhaust gas system of a coal-fired boiler. The physical nature of these materials varies from a wet sludge to a dry powdered material, depending on the process, and their composition comprises either sulfites, sulfates or a mixture thereof.

Fly ash
means the very fine globular particles of silica glass which is a product of burning finely ground coal in a boiler to produce electricity, and is removed from the plant exhaust gases by air emission control devices.

Hazard potential
means the possible adverse incremental consequences that result from the release of water or stored contents due to failure of a dam (or impoundment) or mis-operation of the dam or appurtenances.
3

3
The Hazard Potential Classification System for Dams was developed by the U.S. Army Corps of Engineers for the National Inventory of Dams (
see https://rsgis.crrel.usace.army.mil/apex/f?p=397:1:913698079375545
). Hazard potential ratings do not provide an estimate of the probability of failure or mis-operation, but rather what the consequences of such a failure or mis-operation would be.

High hazard potential surface impoundment
means a surface impoundment where failure or mis-operation will probably cause loss of human life.

Significant hazard potential surface impoundment
means a surface impoundment where failure or mis-operation results in no probable loss of human life, but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns.

Low hazard potential surface impoundment
means a surface impoundment where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the surface impoundment owner's property.

Less than low hazard potential surface impoundment
means a surface impoundment not meeting the definitions for High, Significant, or Low Hazard Potential.

Independent registered professional engineer or hydrologist
means a scientist or engineer who is not an employee of the owner or operator of a CCR landfill or surface impoundment who has received a baccalaureate or post-graduate degree in the natural sciences or engineering and has sufficient training and experience in groundwater hydrology and related fields as may be demonstrated by state registration, professional certifications, or completion of accredited university programs that enable that individual to make sound professional judgments regarding groundwater monitoring, contaminant fate and transport, and corrective action.

Lateral expansion
means a horizontal expansion of the waste boundaries of an existing CCR landfill, or existing CCR surface impoundment made after the effective date of the final rule.

Maximum Contaminant Level (MCL)
means the highest level of a contaminant that is allowed in drinking water under the Safe Drinking Water Act (SDWA). MCLs are set as close to the MCL goals as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards for drinking water.

Minefill
means a project involving the placement of CCRs in coal mine voids for use as fill, grouting, subsidence control, capping, mine sealing, and

treating acid mine drainage, whether for purposes of disposal or for beneficial use, such as mine reclamation.

Natural water table
means the natural level at which water stands in a shallow well open along its length and penetrating the surficial deposits just deeply enough to encounter standing water at the bottom. This level is uninfluenced by groundwater pumping or other engineered activities.

Organosilanes
are organic compounds containing at least one carbon to silicon bond, and are typically used to promote adhesion.

Potential damage case
means those cases with documented MCL exceedances that were measured in ground water beneath or close to the waste source. In these cases, while the association with CCRs has been established, the documented exceedances had not been demonstrated at a sufficient distance from the waste management unit to indicate that waste constituents had migrated to the extent that they could cause human health concerns.

Pozzolanic material
means primarily

vitreous siliceous materials, such as many types of CCRs that, when combined with calcium hydroxide and in the presence of water, exhibit cementitious properties.

Proven damage case
means those cases with (i) Documented exceedances of primary maximum contaminant levels (MCLs) or other health-based standards measured in ground water at sufficient distance from the waste management unit to indicate that hazardous constituents have migrated to the extent that they could cause human health concerns, and/or (ii) where a scientific study provides documented evidence of another type of damage to human health or the environment (
e.g.,
ecological damage), and/or (iii) where there has been an administrative ruling or court decision with an explicit finding of specific damage to human health or the environment. In cases of co-management of CCRs with other industrial waste types, CCRs must be clearly implicated in the reported damage.

Sand and gravel pit, and/or quarry
means an excavation for the commercial extraction of aggregate for use in construction projects. CCRs have historically been used to fill sand and gravel pits and quarries. CCRs are not known to be used to fill metal mines.

Secondary Drinking Water Standards
are non-enforceable federal guidelines regarding cosmetic effects (such as tooth or skin discoloration) or aesthetic effects (such as taste, odor, or color) of drinking water.

Special Wastes
means any of the following wastes that are managed under the modified subtitle C requirements: CCRs destined for disposal.

Surface Water
means all water naturally open to the atmosphere (rivers, lakes, reservoirs, ponds, streams, impoundments, seas, estuaries, etc.).

Uniquely associated wastes
means low-volume wastes other than those defined as CCRs that are related to the coal combustion process. Examples of uniquely associated wastes are precipitation runoff from coal storage piles at the electric utility, waste coal or coal mill rejects that are not of sufficient quality to burn as a fuel, and wastes from cleaning boilers used to generate steam.

CCPs Coal Combustion Products

CCRs Coal Combustion Residuals

CFR Code of Federal Regulations

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

EPA U.S. Environmental Protection Agency

EPCRA Emergency Planning and Community Right-to-Know Act

MCL Maximum Contaminant Level

m/L milligrams per liter

NPDES National Pollutant Discharge Elimination System

NRC National Response Center

PDWS Primary Drinking Water Standard

OSM Office of Surface Mining Reclamation and Enforcement, U.S. Department of the Interior

RCRA Resource Conservation and Recovery Act (42 USCA 6901)

RQ Reportable Quantity

SDWS Secondary Drinking Water Standard

SMCRA Surface Mining Control and Reclamation Act

μg/L micrograms per liter

WQC Federal water quality criteria

D. The Contents of This Preamble Are Listed in the Following Outline

I. Background

A. Why is EPA proposing two options?

1. Basis of Why EPA Is Proceeding With Today's Co-Proposals

2. Brief Description of Today's Co-Proposals

3. Summary of Estimated Regulatory Costs and Benefits

B. What is the statutory authority for this action?

C. Regulation of Wastes Under RCRA Subtitle C

D. Regulation of Solid Wastes Under RCRA Subtitle D

E. Summary of the 1993 and 2000 Regulatory Determinations

F. What are CCRs?

1. Chemical Constituents in CCRs

2. Recent EPA Research on Constituent Leaching From CCRs

G. Current Federal Regulations or Standards Applicable to the Placement of CCRs in Landfills and Surface Impoundments

II. New Information on the Placement of CCRs in Landfills and Surface Impoundments

A. New Developments Since the May 2000 Regulatory Determination

B. CCR Risk Assessment

C. Damage Cases

III. Overview and Summary of the Bevill Regulatory Determination and the Proposed Subtitle C and Subtitle D Regulatory Options

A. Summary of Subtitle C Proposal

B. Summary of Subtitle D Proposal

IV. Bevill Regulatory Determination Relating to CCRs From Electric Utilities

A. Basis for Reconsideration of May 2000 Regulatory Determination

B. RCRA Section 8002(n) Study Factors Environmental Benefits

C. Preliminary Bevill Conclusions and Impact of Reconsideration

D. EPA Is Not Reconsidering the Regulatory Determination Regarding Beneficial Use

1. Why is EPA not proposing to change the determination that CCRs that are beneficially used do not warrant federal regulation?

2. What constitutes beneficial use?

3. Disposal of CCRs in Sand and Gravel Pits and Large Scale Fill Operations Is Not Considered a Beneficial Use

4. Issues Associated With Unencapsulated Beneficial Uses

E. Placement of CCRs in Minefilling Operations

F. EPA Is Not Proposing To Revise the Bevill Determination for CCRs Generated by Non-Utilities

V. Co-Proposed Listing of CCRs as a Special Waste Under RCRA Subtitle C and Special Requirements for Disposal of CCRs Generated by Electric Utilities

A. What is the basis for listing CCRs as a special waste?

1. Criteria for Listing CCRs as a Special Waste and Background on 2010 Risk Assessment

B. Background on EPA's 2010 Risk Assessment

1. Human Health Risks

2. Ecological Risks

C. Consideration of Individual Listing Criteria

1. Toxicity—Factor (i)

2. Concentration of Constituents in Waste—Factor (ii)

3. Migration, Persistence, Degradation, and Bioaccumulation—Factors (iii), (iv), (v), and (vi)

4. Plausible Types of Mismanagement, Quantities of the Waste Generated, Nature and Severity of Effects From Mismanagement—Factors (vii), (viii) and (ix)

5. Action Taken by Other Governmental Agencies or Regulatory Programs Based on the Health or Environmental Hazard Posed by the Waste or Waste Constituent—Factor (x)

6. Other Factors—Factor (xi)

VI. Summary of the Co-Proposed Subtitle C Regulations

A. Special Waste Listing

B. Proposed Special Requirements for CCRs

1. Modification of Technical Standards Under 3004(x)

i. Modification of CCR Landfills and Surface Impoundments From the Section 3004(o) Liner and Leak Detection Requirements

ii. Fugitive Dust Controls

iii. Special Requirements for Stability of CCR Surface Impoundments

iv. Wet-Handling of CCRs, Closure, and Interim Status for Surface Impoundments

v. Proposed Land Disposal Restrictions

2. Proposed Treatment Standards for Non-Wastewaters (Dry CCRs)

3. Proposed Treatment Standards for Wastewaters (Wet-Handled CCRs)

4. Effective Date of the LDR Prohibitions

C. Applicability of Subtitle C Regulations

D. CERCLA Designation and Reportable Quantities

1. Reporting Requirements

2. Basis for RQs and Adjustments

3. Application of the CERCLA Mixture Rule to Listed CCR

4. Correction of Table of Maximum Observed Constituent Concentrations Identified by EPA

E. Listing of CCR as Special Wastes To Address Perceived Stigma Issue

VII. How would the proposed subtitle C requirements be implemented?

A. Effective Dates

B. What are the requirements with which facilities must comply?

1. Generators and Transporters

2. Treatment, Storage, and Disposal Facilities (TSDs)

C. RCRA Section 3010 Notification

D. Permit Requirements

1. Facilities Newly Subject to RCRA Permit Requirements

2. Existing Interim Status Facilities

3. Permitted Facilities

E. Requirements in 40 CFR Parts 264 and 265

VIII. Impacts of a Subtitle C Rule on State Authorization

A. Applicability of the Rule in Authorized States

B. Effect on State Authorization

IX. Summary of the Co-Proposal Regulating CCRs Under Subtitle D Regulations

A. Overview and General Issues

1. Regulatory Approach

2. Notifications

B. Section-by-Section Discussion of RCRA Subtitle D Criteria

1. Proposed Modifications to Part 257, Subpart A

2. General Provisions

3. Definitions

4. Location Restrictions

5. Design Requirements

6. Operating Requirements

7. Ground Water Monitoring/Corrective Action

8. Closure and Post-Closure Care

9. Financial Assurance

10. Off-Site Disposal

11. Alternative RCRA Subtitle D Approaches

X. How would the proposed subtitle D regulations be implemented?

A. Effective Dates

B. Implementation and Enforcement of Subtitle D Requirements

XI. Impact of a Subtitle D Regulation on State Programs

XII. Impacts of the Proposed Regulatory Alternatives

A. What are the economic impacts of the proposed regulatory alternatives?

B. Benefits Not Quantified in the RIA

1. Non-Quantified Plant and Wildlife Protection Benefits

2. Non-Quantified Surface Water Protection Benefits

3. Non-Quantified Ambient Air Protection Benefits

C. Comparison of Costs to Benefits for the Regulatory Alternatives

D. What are the potential environmental and public health impacts of the proposed regulatory alternatives?

1. Environmental and Public Health Impacts Estimated in the RIA

2. Environmental and Public Health Impacts Not Estimated in the RIA

XIII. Other Alternatives EPA Considered

XIV. Is the EPA soliciting comments on specific issues?

XV. Executive Orders and Laws Addressed in This Action

A. Executive Order 12866: Regulatory Planning and Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

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

G. Executive Order 13045: Protection of Children From Environmental Health & Safety Risks

H. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution, or Use

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations

APPENDIX to the Preamble: Documented Damages From CCR Management Practices

I. Background

A. Why is EPA proposing two options?

1. Basis of Why EPA Is Proceeding With Today's Co-Proposals

EPA is revisiting its regulatory determination for CCRs under the Bevill amendment. This decision is driven in part by the failure of a surface impoundment retaining wall in Kingston, TN in December 2009. Deciding upon the appropriate course of action to address over 100 million tons per year of CCRs is an extremely important step. In developing this proposal, EPA conducted considerable data gathering and analysis. While the public was able to comment on significant portions of our analyses in August 2007, as part of a Notice of Data Availability, there are differing views regarding the meaning of EPA's information and what course of action EPA should take. In part, the differing views are fueled by the complex data, analyses, legislation, implications of available options, possible unintended consequences, and a decision process, all of which pose considerations that could justify EPA selecting a RCRA subtitle C approach or selecting a RCRA subtitle D approach.

Deciding whether or not to maintain the Bevill exemption for CCRs, entails an evaluation of the eight RCRA Section 8002(n) study factors:

• Source and volumes of CCRs generated per year

• Present disposal and utilization practices

• Potential danger, if any, to human health and the environment from the disposal and reuse of CCRs

• Documented cases in which danger to human health or the environment from surface runoff or leachate has been proved

• Alternatives to current disposal methods

• The cost of such alternatives

• The impact of the alternatives on the use of coal and other natural resources

• The current and potential utilization of CCRs

Ultimately, the approach selected will need to ensure that catastrophic releases such as occurred at the Tennessee Valley Authority's (TVA's) Kingston, Tennessee facility do not occur and that other types of damage cases associated with CCR surface impoundments and landfills are prevented. Thus, this process requires EPA to balance the eight factors, which ultimately rests on a policy judgment. This is further complicated in this case because the facts identified under each of the individual factors are even subject to widely varying perspectives. For example, in considering the alternatives to current disposal methods, some claim that RCRA subtitle C would significantly lessen beneficial use while others
see
beneficial use expanding as disposal becomes more costly; some
see
damage cases as substantial, while others note very few incidences of significant off-site contamination.

Given the inherently discretionary nature of the decision, the complexities of the scientific analyses, and the controversy of the issue, EPA wants to ensure that the ultimate decision is based on the best available data, and is taken with the fullest possible extent of public input. As discussed in section IV in greater detail, there are a number of issues on which additional or more recent information would be useful in

allowing the Agency to reach a final decision. In the absence of this information, EPA has not yet reached a conclusion as to how to strike the appropriate balance among these eight factors and so is presenting two proposals for federal regulation of CCRs.

As EPA weighs the eight Bevill study factors to reach our ultimate decision, EPA will be guided by the following principles, which are reflected in the discussions throughout this preamble. The first is that EPA's actions must ultimately be protective of human health and the environment. Second, any decision must be based on sound science. Finally, in conducting this rulemaking, EPA wants to ensure that our decision processes are transparent and encourage the greatest degree of public participation. Consequently, to further the public's understanding and ability to comment on all the issues facing the Agency, within this proposal, EPA identifies a series of scientific, economic, and materials management issues on which we are seeking comment from the public to strengthen our knowledge of the impact of EPA's decision.

There are three key areas of analyses where EPA is seeking comment: The extent of existing damage cases, the extent of the risks posed by the mismanagement of CCRs, and the adequacy of State programs to ensure proper management of CCRs (
e.g.,
is groundwater monitoring required of CCR landfills and surface impoundments). Since the 2007 NODA, EPA received new reports from industry and environmental and citizen groups regarding damage cases. Industry provided information indicating that many of EPA's listed proven damage cases do not meet EPA's criteria for a damage case to be proven. Environmental and citizen groups, on the other hand, reported that there are additional damage cases of which EPA is unaware. EPA's analysis, as well as the additional information from industry and environmental and citizen groups, which is in the docket for this proposal, needs to undergo public review, with the end result being a better understanding of the nature and number of damage cases. In addition, as discussed at length in sections II and IV, a number of technical questions have been raised regarding EPA's quantitative groundwater risk assessment. The Agency would implement similar technical controls under RCRA subtitle C or D. Therefore, a central issue is the adequacy of State programs. Under either regulatory approach, State programs will have key implementation roles. This is a very complex area to evaluate. For example, as EPA reports that 36% of the States do not have minimum liner requirements for CCR landfills, and 67% do not have liner requirements for CCR surface impoundments, we also observe that nearly all new CCR landfills and surface impoundments are constructed with liners. It should also be recognized that while states currently have considerable expertise in their State dam safety programs, those programs do not tend to be part of State solid waste or clean water act programs, and so, oversight may not be adequately captured in EPA's existing data. In several areas, there are these types of analytical tensions that warrant careful consideration by the public and EPA. This proposal requests states and others to provide further information on state programs, including the prevalence of groundwater monitoring at existing facilities (an area where our information is nearly 15 years old) and why state programs may address groundwater monitoring and risks differently for surface impoundments located proximate to rivers.

The results of the risk analysis demonstrate significant risks from surface impoundments. A common industry practice, however, is to place surface impoundments right next to water bodies. While the Agency's population risk assessment analysis accounted for adjacent water bodies, the draft risk assessment that presents individual risk estimates does not account for the presence of adjacent water bodies in the same manner that the population risk assessment did. EPA is requesting public comment on the exact locations of CCR waste management units so that the Agency can more fully account for water bodies that may exist between a waste management unit and a drinking water well (and thus, could potentially intercept a contaminated groundwater plume). EPA is also requesting comments on how the risk assessment should inform the final decision.

While the Agency believes the analyses conducted are sound, today's co-proposal of two options reflects our commitment to use the public process fully to ensure the best available scientific and regulatory impact analyses are considered in our decision. The final course of action will fully consider these legitimate and complex issues, and will result in the selection of a regulatory structure that best addresses the eight study factors identified in section 8002(n) of RCRA, and ensures protection of human health and the environment.

2. Brief Description of Today's Co-Proposals

a. Summary of Subtitle C Proposal

In combination with its proposal to reverse the Bevill determination for CCRs destined for disposal, EPA is proposing to list as a special waste, to be regulated under the RCRA subtitle C regulations, CCRs from electric utilities and independent power producers when destined for disposal in a landfill or surface impoundment. These CCRs would be regulated from the point of their generation to the point of their final disposition, including during and after closure of any disposal unit. This would include the generator and transporter requirements and the requirements for facilities managing CCRs, such as siting, liners (with modification), run-on and run-off controls, groundwater monitoring, fugitive dust controls, financial assurance, corrective action, including facility-wide corrective action, closure of units, and post-closure care (with certain modifications). In addition, facilities that dispose of, treat, or, in many cases, store, CCRs also would be required to obtain permits for the units in which such materials are disposed, treated, and stored. The rule would also regulate the disposal of CCRs in sand and gravel pits, quarries, and other large fill operations as a landfill.

To address the potential for catastrophic releases from surface impoundments, we also are proposing requirements for dam safety and stability for impoundments that, by the effective date of the final rule, have not closed consistent with the requirements. We are also proposing land disposal restrictions and treatment standards for CCRs, as well as a prohibition on the disposal of treated CCRs below the natural water table.

b. Summary of Subtitle D Proposal

In combination with today's proposal to leave the Bevill determination in place, EPA is proposing to regulate CCRs disposed of in surface impoundments or landfills under RCRA subtitle D requirements which would establish national criteria to ensure the safe disposal of CCRs in these units. The units would be subject to, among other things, location standards, composite liner requirements (new landfills and surface impoundments would require composite liners; existing surface impoundments without liners would have to retrofit within five years, or cease receiving CCRs and close); groundwater monitoring and corrective action standards for releases from the unit; closure and post-closure care

requirements; and requirements to address the stability of surface impoundments. We are also soliciting comments on requiring financial assurance. The rule would also regulate the disposal of CCRs in sand and gravel pits, quarries, and other large fill operations as a landfill. The rule would not regulate the generation, storage or treatment of CCRs prior to disposal. Because of the scope of subtitle D authority, the rule would not require permits, nor could EPA enforce the requirements. Instead, states or citizens could enforce the requirements under RCRA citizen suit authority; the states could also enforce any state regulation under their independent state enforcement authority.

EPA is also considering a potential modification to the subtitle D option, called “D prime” in the following table. Under this option, existing surface impoundments would not have to close or install composite liners but could continue to operate for their useful life. In the “D prime” option, the other elements of the subtitle D option would remain the same.

3. Summary of Estimated Regulatory Costs and Benefits

For the purposes of comparing the estimated regulatory compliance costs to the monetized benefits for each regulatory option, the Regulatory Impact Analysis (RIA) computed two comparison indicators: Net benefits (
i.e.,
benefits minus costs), and benefit/cost ratio (
i.e.,
benefits divided by costs). Table 1 below provides a summary of estimated regulatory costs and benefits for three regulatory options, based on the 7% discount rate base case and the 50-year period-of-analysis applied in the RIA. Furthermore, this benefit and cost summary table displays ranges of net benefit and benefit/cost results across three different scenarios concerning the potential impacts of each option on the future annual beneficial use of CCRs under each option. The first scenario presents the potential impact scenario that assumes that the increased future annual cost of RCRA-regulated CCR disposal will induce coal-fired electric utility plants to increase beneficial use of CCRs. The second scenario presents a potential market stigma effect under the subtitle C option which will induce a decrease in future annual CCR beneficial use. The third scenario assumed that beneficial use of CCRs continues according to its recent trend line without any future change as a result of any of the regulatory options. The RIA estimates both the first and second scenario incrementally in relation to the third scenario no change trend line. Table 1 shows the range of impacts and associated ranges of net benefits and benefit-cost ratios across these three beneficial use scenarios for each regulatory option. While each of these three scenario outcomes may be possible, EPA's experience with the RCRA program indicates that industrial generators of RCRA-regulated wastes are often able to increase recycling and materials recovery rates after a subtitle C regulation. Section XII in this preamble provides additional discussion of these estimates.

Table 1—Summary Table Comparison of Regulatory Benefits to Costs—Ranging Over All Three Beneficial Use Scenarios
[$Millions @ 2009$ prices and @ 7% discount rate over 50-year future period-of-analysis 2012 to 2061]

Subtitle C “Special waste”
Subtitle D
Subtitle “D prime”

A. Present Values:

1. Regulatory Costs:
$20,349
$8,095
$3,259.

2. Regulatory Benefits:
$87,221 to $102,191
$34,964 to $41,761
$14,111 to $17,501.

3. Net Benefits (2-1)
($251,166) to $81,842
($6,927) to $33,666
($2,666) to $14,242.

4. Benefit/Cost Ratio (2/1)
(11.343) to 5.022
0.144 to 5.159
0.182 to 5.370.

B. Average Annualized Equivalent Values:*

1. Regulatory Costs
$1,474
$587
$236.

2. Regulatory Benefits:
$6,320 to $7,405
$2,533 to $3,026
$1,023 to $1,268.

3. Net Benefits (2-1)
($18,199) to $5,930
($502) to $2,439
($193) to $1,032.

4. Benefit/Cost Ratio (2/1)
(11.347) to 5.022
0.145 to 5.159
0.182 to 5.370.

*

Note:
Average annualized equivalent values calculated by multiplying 50-year present values by a 50-year 7% discount rate “capital recovery factor” of 0.07246.

B. What is the statutory authority for this action?

These regulations are being proposed under the authority of sections 1008(a), 2002(a), 3001, 3004, 3005, and 4004 of the Solid Waste Disposal Act of 1970, as amended by the Resource Conservation and Recovery Act of 1976 (RCRA), as amended by the Hazardous and Solid Waste Amendments of 1984 (HSWA), 42 U.S.C. 6907(a), 6912(a), 6921,6924, 6925 and 6944. These statutes, combined, are commonly referred to as “RCRA.”

RCRA section 1008(a) authorizes EPA to publish “suggested guidelines for solid waste management.” 42 U.S.C. 6907(a). Such guidelines must provide a technical and economic description of the level of performance that can be achieved by available solid waste management practices that provide for protection of human health and the environment.

RCRA section 2002 grants EPA broad authority to prescribe, in consultation with federal, State, and regional authorities, such regulations as are necessary to carry out the functions under federal solid waste disposal laws. (42 U.S.C. 6912(a)).

RCRA section 3001(b) requires EPA to list particular wastes that will be subject to the requirements established under subtitle C. (42 U.S.C. 6921(b)). The regulation listing such wastes must be based on the listing criteria established pursuant to section 3001(a), and codified at 40 CFR 261.11.

Section 3001(b)(3)(A) of RCRA established a temporary exemption for fly ash waste, bottom ash waste, slag waste, and flue gas emission control waste generated primarily from the combustion of coal or other fossil fuels, among others, and required the Agency to conduct a study of those wastes and, after public hearings and an opportunity for comment, determine whether these wastes should be regulated pursuant to subtitle C requirements (42 U.S.C. 6921 (b)(3)(A)).

Section 3004 of RCRA generally requires EPA to establish standards applicable to the treatment, storage, and disposal of hazardous waste to ensure that human health and the environment are protected. 42 U.S.C. 6924. Sections

3004(c) and (d) prohibit free liquids in hazardous waste landfills. Sections 3004(g) and (m) prohibit land disposal of hazardous wastes, unless, before disposal, those wastes meet treatment standards established by EPA that will “substantially diminish the toxicity of the waste or substantially reduce the likelihood of migration of hazardous constituents from the waste so that short-term and long-term threats are minimized.” (42 U.S.C. 6924(c), (d), (g), and (m)).

RCRA section 3004(x) allows the Administrator to tailor certain specified requirements for particular categories of wastes, including those that are the subject of today's proposal, namely “fly ash waste, bottom ash waste, and flue gas emission control wastes generated primarily from the combustion of coal or other fossil fuels” (42 U.S.C. 6924(x)). EPA is authorized to modify the requirements of sections 3004 (c), (d), (e), (f), (g), (o), and (u), and section 3005(j), to take into account the special characteristics of the wastes, the practical difficulties associated with implementation of such requirements, and site-specific characteristics, including but not limited to the climate, geology, hydrology and soil chemistry at the site. EPA may only make such modifications, provided the modified requirements assure protection of human health and the environment. (42 U.S.C. 6924(x)).

RCRA section 3005 generally requires any facility that treats, stores, or disposes of wastes identified or listed under subtitle C, to have a permit. 42 U.S.C. 6925(a). This section also generally imposes requirements on facilities that become newly subject to the permitting requirements as a result of regulatory changes, and so can continue to operate for a period until they obtain a permit—
i.e.,
“interim status facilities.” 42 U.S.C. 6925(e), (i), (j). Congress imposed special requirements on interim status surface impoundments in section 3005(j). In order to continue receiving wastes, interim status surface impoundments are generally required to retrofit the impoundment within 4 years, to install a double liner, with a leachate collection system, and groundwater monitoring. 42 U.S.C. 6925(j)(6). In addition, wastes disposed into interim status surface impoundments must meet the land disposal restrictions in EPA's regulations, or the unit must be annually dredged. 42 U.S.C. 6925(j)(11).

RCRA Section 4004 generally requires EPA to promulgate regulations containing criteria for determining which facilities shall be classified as sanitary landfills (and not open dumps) so that there is no reasonable probability of adverse effects on health or the environment from disposal of solid wastes at such facilities.

C. Regulation of Wastes Under RCRA Subtitle C

Solid wastes may become subject to regulation under subtitle C of RCRA in one of two ways. A waste may be subject to regulation if it exhibits certain hazardous properties, called “characteristics,” or if EPA has specifically listed the waste as hazardous.
See
42 U.S.C. 6921(a). EPA's regulations in the Code of Federal Regulations (40 CFR) define four hazardous waste characteristic properties: Ignitability, corrosivity, reactivity, or toxicity (
See
40 CFR 261.21-261.24). All generators must determine whether or not a waste exhibits any of these characteristics by testing the waste, or by using knowledge of the process that generated the waste (
see
§ 262.11(c)). While not required to sample the waste, generators will be subject to enforcement actions if found to be improperly managing wastes that exhibit one or more of the characteristics.

EPA may also conduct a more specific assessment of a waste or category of wastes and “list” them if they meet the criteria set out in 40 CFR 261.11. Under the third criterion, at 40 CFR 261.11(a)(3), a waste will be listed if it contains hazardous constituents identified in 40 CFR part 261, Appendix VIII, and if, after considering the factors noted in this section of the regulations, we “conclude that the waste is capable of posing a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed.” We place a chemical on the list of hazardous constituents on Appendix VIII only if scientific studies have shown a chemical has toxic effects on humans or other life forms. When listing a waste, we also add the hazardous constituents that serve as the basis for listing the waste to 40 CFR part 261, Appendix VII.

The regulations at 40 CFR 261.31 through 261.33 contain the various hazardous wastes that EPA has listed to date. Section 261.31 lists wastes generated from non-specific sources, known as “F-wastes,” that are usually generated by various industries or types of facilities, such as “wastewater treatment sludges from electroplating operations” (
see
EPA Hazardous Waste No. F006). Section 261.32 lists wastes generated from specific industry sources, known as “K-wastes,” such as “Spent potliners from primary aluminum production” (
see
EPA Hazardous Waste No. K088). Section 261.33 contains lists of commercial chemical products and other materials, known as “P-wastes” or “U-wastes,” that become hazardous wastes when they are discarded or intended to be discarded.

As discussed in greater detail later in this proposal, EPA is considering whether to codify a listing of CCRs that are disposed of in landfills or surface impoundments, in a new section of the regulations, as “Special Wastes.” EPA is considering creating this new category of wastes, in part, to reflect the fact that these wastes would be subject to modified regulatory requirements using the authority provided under section 3004(x) of RCRA (
e.g.,
the modified CCR landfill and surface impoundment liner and leak detection system requirements, the effective dates for the land disposal restrictions, and the surface impoundment retrofit requirements).

If a waste exhibits a hazardous characteristic or is listed under subtitle C, then it is subject to the requirements of RCRA subtitle C, and the implementing regulations found in 40 CFR parts 260 through 268, parts 270 to 279, and part 124. These requirements apply to persons who generate, transport, treat, store or dispose of such waste and establish rules governing every phase of the waste's management from its generation to its final disposition and beyond. Facilities that treat, store or dispose of hazardous wastes require a permit which incorporates all of the design and operating standards established by EPA rules, including standards for piles, landfills, and surface impoundments. Under RCRA subtitle C requirements, land disposal of hazardous waste is prohibited unless the waste is first treated to meet the treatment standards (or meets the treatment standards as generated) established by EPA that minimize threats to human health and the environment posed by the land disposal of the waste, or unless the waste is disposed in a unit from which there will be no migration of hazardous constituents for as long as the waste remains hazardous. In addition, RCRA subtitle C facilities are required to clean up any releases of hazardous waste or constituents from solid waste management units at the facility, as well as beyond the facility boundary, as necessary to protect human health and the environment. RCRA subtitle C also requires that permitted facilities demonstrate that they have adequate financial resources (
i.e.,
financial assurance) for obligations, such as closure, post-closure care, necessary

clean up, and any liability from facility operations.

The RCRA subtitle C requirements are generally implemented under state programs that EPA has authorized to operate in lieu of the federal program, based upon a determination that the state program is no less stringent than the federal program. In a state that operates under an authorized program, any revisions made to EPA requirements are generally effective as part of the federal RCRA program in that state only after the state adopts the revised requirement, and EPA authorizes the state requirement. The exception applies with respect to requirements implementing statutory provisions added to subtitle C by the 1984 Hazardous and Solid Waste Amendments to RCRA; such requirements are immediately effective in all states, and are enforced by EPA.

All RCRA hazardous wastes are also hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as defined in section 101(14)(C) of the CERCLA statute. This applies to wastes listed in §§ 261.31 through 261.33, as well as any wastes that exhibits a RCRA hazardous characteristic. Table 302.4 at 40 CFR 302.4 lists the CERCLA hazardous substances along with their reportable quantities (RQs). Anyone spilling or releasing a hazardous substance at or above its RQ must report the release to the National Response Center, as required in CERCLA Section 103. In addition, Section 304 of the Emergency Planning and Community Right-to-Know Act (EPCRA) requires facilities to report the release of a CERCLA hazardous substance at or above its RQ to State and local authorities. Today's rule proposes an approach for estimating whether released CCRs exceed an RQ. Wastes listed as special wastes will generally be subject to the same requirements under RCRA subtitle C and CERCLA as are hazardous wastes, although as discussed elsewhere in this preamble, EPA is proposing to revise certain requirements under the authority of section 3004(x) of RCRA to account for the large volumes and unique characteristics of these wastes.

D. Regulation of Solid Wastes Under RCRA Subtitle D

Solid wastes that are neither a listed and/or characteristic hazardous waste are subject to the requirements of RCRA subtitle D. Subtitle D of RCRA establishes a framework for Federal, State, and local government cooperation in controlling the management of nonhazardous solid waste. The federal role in this arrangement is to establish the overall regulatory direction, by providing minimum nationwide standards for protecting human health and the environment, and to providing technical assistance to states for planning and developing their own environmentally sound waste management practices. The actual planning and direct implementation of solid waste programs under RCRA subtitle D, however, remains a state and local function, and the act authorizes States to devise programs to deal with State-specific conditions and needs. That is, EPA has no role in the planning and direct implementation of solid waste programs under RCRA subtitle D.

Under the authority of sections 1008(a)(3) and 4004(a) of subtitle D of RCRA, EPA first promulgated the Criteria for Classification of Solid Waste Disposal Facilities and Practices (40 CFR part 257) on September 13, 1979. These subtitle D Criteria establish minimum national performance standards necessary to ensure that “no reasonable probability of adverse effects on health or the environment” will result from solid waste disposal facilities or practices. Practices not complying with the criteria constitute “open dumping” for purposes of the Federal prohibition on open dumping in section 4005(a). EPA does not have the authority to enforce the prohibition directly (except in situations involving the disposal or handling of sludge from publicly-owned treatment works, where Federal enforcement of POTW sludge-handling facilities is authorized under the CWA). States and citizens may enforce the prohibition on open dumping using the authority under RCRA section 7002. EPA, however, may act only if the handling, storage, treatment, transportation, or disposal of such wastes may present an imminent and substantial endangerment to health or the environment (RCRA 7003). In addition, the prohibition may be enforced by States and other persons under section 7002 of RCRA.

In contrast to subtitle C, RCRA subtitle D requirements relate only to the disposal of the solid waste, and EPA does not have the authority to establish requirements governing the generation, transportation, storage, or treatment of such wastes prior to disposal. Moreover, EPA would not have administrative enforcement authority to enforce any RCRA subtitle D criteria for CCR facilities, authority to require states to issue permits for them or oversee those permits, nor authority for EPA to determine whether any state permitting program for CCR facilities is adequate. Subtitle D of RCRA also provides less extensive authority to establish requirements relating to the cleanup (or corrective action) and financial assurance at solid waste facilities.

EPA regulations affecting RCRA subtitle D facilities are found at 40 CFR parts 240 through 247, and 255 through 258. The existing part 257 criteria include general environmental performance standards addressing eight major topics: Floodplains (§ 257.3-1), endangered species (§ 257.3-2), surface water (§ 257.3-3), ground water (§ 257.3-4), land application (§ 257.35), disease (§ 257.3-6), air (§ 257.3-7), and safety (§ 257.3-8). EPA has also established regulations for RCRA subtitle D landfills that accept conditionally exempt small quantity generator hazardous wastes, and household hazardous wastes (
i.e.,
“municipal solid waste”) at 40 CFR Part 258, but these are of limited relevance to CCRs, which fall into neither category of wastes.

E. Summary of the 1993 and 2000 Regulatory Determinations

Section 3001(b)(3)(A)(i) of RCRA (known as the Bevill exclusion or exemption) excluded certain large-volume wastes generated primarily from the combustion of coal or other fossil fuels from being regulated as hazardous waste under subtitle C of RCRA, pending completion of a Report to Congress required by Section 8002(n) of RCRA and a determination by the EPA Administrator either to promulgate regulations under RCRA subtitle C or to determine that such regulations are unwarranted.

In 1988, EPA published a Report to Congress on Wastes from the Combustion of Coal by Electric Utility Power Plants (EPA, 1988). The report, however, did not address co-managed utility CCRs, other fossil fuel wastes that are generated by utilities, and wastes from non-utility boilers burning any type of fossil fuel. Further, because of other priorities, EPA did not complete its Regulatory Determination on fossil fuel combustion (FFC) wastes at that time.

In 1991, a suit was filed against EPA for failure to complete a Regulatory Determination on FFC wastes (
Gearhart
v.
Reilly
Civil No. 91-2345 (D.D.C.), and on June 30, 1992, the Agency entered into a Consent Decree that established a schedule for EPA to complete the Regulatory Determinations for all FFC wastes. Specifically, FFC wastes were divided into two categories: (1) Fly ash, bottom ash, boiler slag, and flue gas emission control waste from the combustion of coal by electric utilities and independent commercial power

producers, and (2) all remaining wastes subject to RCRA Sections 3001(b)(3)(A)(i) and 8002(n)—that is, large volume coal combustion wastes generated at electric utility and independent power producing facilities that are co-managed together with certain other coal combustion wastes; coal combustion wastes generated at non-utilities; coal combustion wastes generated at facilities with fluidized bed combustion technology; petroleum coke combustion wastes; wastes from the combustion of mixtures of coal and other fuels (
i.e.,
co-burning of coal with other fuels where coal is at least 50% of the total fuel); wastes from the combustion of oil; and wastes from the combustion of natural gas.

On August 9, 1993, EPA published its Regulatory Determination for the first category of wastes (58 FR 42466,
http://www.epa.gov/epawaste/nonhaz/industrial/special/mineral/080993.pdf
), concluding that regulation under subtitle C of RCRA for these wastes was not warranted. To make an appropriate determination for the second category, or “remaining wastes,” EPA concluded that additional study was necessary. Under the court-ordered deadlines, the Agency was required to complete a Report to Congress by March 31, 1999, and issue a Regulatory Determination by October 1, 1999.

In keeping with its court-ordered schedule, and pursuant to the requirements of Section 3001(b)(3)(A)(i) and Section 8002(n) of RCRA, EPA prepared a Report to Congress on the remaining FFC wastes in March 1999 (
http://www.epa.gov/epaoswer/other/fossil/volume_2.pdf
). The report addresses the eight study factors required by Section 8002(n) of RCRA for FFC wastes (
see
discussion in section IV. B).

On May 22, 2000, EPA published its Regulatory Determination on wastes from the combustion of fossil fuels for the remaining wastes (65 FR 32214,
http://www.epa.gov/fedrgstr/EPA-WASTE/2000/May/Day-22/f11138.htm
). In its Regulatory Determination, EPA concluded that the remaining wastes were largely identical to the high-volume monofilled wastes, which remained exempt based on the 1993 Regulatory Determination. The high volume wastes simply dominate the waste characteristics even when co-managed with other wastes, and thus the May 2000 Regulatory Determination addressed not only the remaining wastes, but effectively reopened the decision on CCRs that went to monofills.

EPA concluded that these wastes could pose significant risks if not properly managed, although the risk information was limited. EPA identified and discussed a number of documented proven damage cases, as well as cases indicating at least a potential for damage to human health and the environment, but did not rely on its quantitative groundwater risk assessment, as EPA concluded that it was not sufficiently reliable. However, EPA concluded that significant improvements were being made in waste management practices due to increasing state oversight, although gaps remained in the current regulatory regime. On this basis, the Agency concluded to retain the Bevill exemption, and stated we would issue a regulation under subtitle D of RCRA, establishing minimum national standards. Those subtitle D standards have not yet been issued. (Today's proposal could result in the development of the subtitle D standards consistent with the May 2000 Regulatory Determination, or with a revision of the determination, or the issuance of subtitle C standards under RCRA.)

EPA also explicitly stated in the May 2000 Regulatory Determination that the Agency would continue to review the issues, and would reconsider its decision that subtitle C regulations were unwarranted based on a number of factors. EPA noted that its ongoing review would include (1) “the extent to which [the wastes] have caused damage to human health or the environment;” (2) the adequacy of existing regulation of the wastes; (3) the results of an NAS report regarding the adverse human health effects of mercury;
4

and (4) “risk posed by managing coal combustion solid wastes if levels of mercury or other hazardous constituents change due to any future Clean Air Act air pollution control requirements for coal burning utilities” and that these efforts could result in a subsequent revision to the Regulatory Determination. For a further discussion of the basis for the Agency's determination,
see
section IV below.

4
Toxicological Effects of Methylmercury, National Academy of Sciences, July 2000 (
http://books.nap.edu/catalog.php?record_id=9899#toc
). EPA has not taken any actions regarding the May 2000 Regulatory Determination as a result of the NAS report.

F. What are CCRs?

CCRs are residuals from the combustion of coal. For purposes of this proposal, CCRs are fly ash, bottom ash, boiler slag (all composed predominantly of silica and aluminosilicates), and flue gas desulfurization materials (predominantly Ca-SO
X
compounds) that were generated from processes intended to generate power.

Fly ash is a product of burning finely ground coal in a boiler to produce electricity. Fly ash is removed from the plant exhaust gases primarily by electrostatic precipitators or baghouses and secondarily by wet scrubber systems. Physically, fly ash is a very fine, powdery material, composed mostly of silica. Nearly all particles are spherical in shape.

Bottom ash is comprised of agglomerated coal ash particles that are too large to be carried in the flue gas. Bottom ash is formed in pulverized coal furnaces and is collected by impinging on the furnace walls or falling through open grates to an ash hopper at the bottom of the furnace. Physically, bottom ash is coarse, with grain sizes spanning from fine sand to fine gravel, typically grey to black in color, and is quite angular with a porous surface structure.

Boiler slag is the molten bottom ash collected at the base of slag tap and cyclone type furnaces that is quenched with water. When the molten slag comes in contact with the quenching water, it fractures, crystallizes, and forms pellets. This boiler slag material is made up of hard, black, angular particles that have a smooth, glassy appearance.

Flue Gas Desulfurization (FGD) material is produced through a process used to reduce sulfur dioxide (SO
2
) emissions from the exhaust gas system of a coal-fired boiler. The physical nature of these materials varies from a wet sludge to a dry powdered material, depending on the process. The wet sludge generated from the wet scrubbing process using a lime-based reagent is predominantly calcium sulfite, while the wet sludge generated from the wet scrubbing process using a limestone-based reagent is predominantly calcium sulfate. The dry powdered material from dry scrubbers that is captured in a baghouse consists of a mixture of sulfites and sulfates.

CCRs are managed in either wet or dry disposal systems. In wet systems, materials are generally sluiced via pipe to a surface impoundment. The material can be generated wet, such as FGD, or generated dry and water added to facilitate transport (
i.e.
sluiced) through pipes. In dry systems, CCRs are transported in its dry form to landfills for disposal.

1. Chemical Constituents in CCRs

The chemical characteristics of CCRs depend on the type and source of coal, the combustion technology, and the pollution control technology employed. For the 1999 Report to Congress and the May 2000 Regulatory Determination, EPA developed an extensive database

on the leaching potential of CCR constituents using the toxicity characteristic leaching procedure (TCLP) from a number of sources. More recent data on the composition of CCRs, including their leaching potential, have been collected and are discussed in the next sub-section. The CCR constituent database (available in the docket to this proposal) contains data on more than 40 constituents. Table 2 presents the median compositions of trace element TCLP leachates of each of the main four types of large volume CCRs (fly ash, bottom ash, boiler slag, and FGD gypsum). (Additional information, including the range of TCLP values, is available in the docket or on-line in the documents identified in the footnotes to the following table.)

Table 2—TCLP Median Compositions of Coal-Fired Utility Large-Volume CCRs
5
(mg/l)

Constituent
Fly ash
Bottom ash
Boiler slag
FGD

As
0.066
0.002
0.002
0.290

Ba
0.289
0.290
0.260
0.532

B
0.933
0.163
n/a
—

Cd
0.012
0.005
0.0018
0.010

Cr
VI

0.203
0.010
0.003
0.120

Cu
n/a
n/a
0.050
n/a

Pb
0.025
0.005
0.0025
0.120

Hg
0.0001
0.0001
0.0002
0.0001

Se
0.020
0.0013
0.0025
0.280

Ag
0.005
0.0050
0.0001
0.060

V
0.111
0.0050
0.010
—

Zn
0.285
0.015
0.075
—

n/a = data not available.
-- = too few data points to calculate statistics.
Source: Data from supporting documentation to the 1993 Regulatory Determination; values below the detection limit were treated as one-half the detection limit.

The composition

of FGD gypsum depends on the position within the air emissions control system where the SO
2
component is subject to scrubbing: If scrubbing takes place up stream of the removal of fly ash particulates, the FGD would actually comprise a mix of both components. Table 3 presents mean TCLP trace element compositions of FGD gypsum generated by a scrubbing operation that is located down stream from the particulate collection elements of the air emissions control system; it therefore represents an `end member' FGD gypsum.

5
Compiled from Tables 3-1, 3-3, 3-5 and 3-7, in: Technical Background Document for the Report to Congress on Remaining Wastes from Fossil Fuel Combustion: Waste Characteristics, March 15, 1999 (
http://www.epa.gov/epawaste/nonhaz/industrial/special/fossil/ffc2_399.pdf
).

Table 3—FGD Gypsum TCLP Compositions (mg/l) From: (1) Two Ohio Power Plants *
6
(Mean Data); (2) 12 Samples of Commercial Wallboard Produced From Synthetic Gypsum **
7
(Median Data)

Constituent
Cardinal Plant *
Bruce Mansfield Plant *
Synthetic Gypsum **

As
<0.006
0.0075
0.00235

Ba
0.373
0.270
0.043

B
0.137
0.0255
n/a

Cd
0.00167
0.00055
0.00145

Cr
0.00587
0.00575
0.0047

Cu
<0.001
<0.001
n/a

Pb
<0.003
<0.003
0.0006

Hg

1.8×10
−5

2.6×10
−6

<0.0003

Se
0.0123
<0.011
0.044

V
<0.001
0.002
n/a

Zn
0.170
0.0560
n/a

Ag
n/a
n/a
<0.00005

n/a = data not available.

The contaminants

of most environmental concern in CCRs are antimony, arsenic, barium, beryllium, cadmium, chromium, lead, mercury, nickel, selenium, silver and thallium. Although these metals rarely exceed the RCRA hazardous waste toxicity characteristic (TC), because of the mobility of metals and the large size of typical disposal units, metals (especially arsenic) have leached at levels of concern from unlined landfills and surface impoundments. In addition, it should also be noted that since the Agency announced its May 2000 Regulatory Determination, EPA has revised the maximum contaminant level (MCL) for arsenic,
8

without a corresponding revision of the TC. As a result, while arsenic levels are typically well below the TC, drinking water risks from contaminated groundwater due to releases from landfills and impoundments may still be high. Also, as discussed below, a considerable body of evidence has emerged indicating that the TCLP alone is not a good predictor

of the mobility of metals in CCRs under a variety of different conditions. This issue is further discussed in the following subsection.

6
Compiled from: Table 3-5, in: An Evaluation of Flue Gas Desulfurization Gypsum for Abandoned Mine Land Reclamation, Rachael A. Pasini, Thesis, The Ohio State University, 2009.

7
Compiled from: Table 10, in: Fate of Mercury in Synthetic Gypsum Used for Wallboard Production, J. Sanderson
et al.,
USG Corporation, Final Report prepared for NETL, June 2008.

8

See

http://www.epa.gov/safewater/arsenic/regulations.html.

From Tables 2 and 3 above, it is evident that each of the main four types of CCRs, when subjected to a TCLP leach test, yields a different amount of trace element constituents. EPA is soliciting public comments on whether, in light of these differences in the mobility of hazardous metals between the four major types of CCRs, regulatory oversight should be equally applied to each of these CCR types when destined for disposal.

2. Recent EPA Research on Constituent Leaching From CCRs

Changes to fly ash and other CCRs are expected to occur as a result of increased use and application of advanced air pollution control technologies in coal-fired power plants. These technologies include flue gas desulfurization (FGD) systems for SO
2
control, selective catalytic reduction (SCR) systems for NO
X
control, and activated carbon injection systems for mercury control. These technologies are being installed or are expected to be installed in response to federal regulations, state regulations, legal consent decrees, and voluntary actions taken by industry to adopt more stringent air pollution controls. Use of more advanced air pollution control technology reduces air emissions of metals and other pollutants in the flue gas of a coal-fired power plant by capturing and transferring the pollutants to the fly ash and other air pollution control residues. The impact of changes in air pollution control on the characteristics of CCRs and the leaching potential of metals is the focus of ongoing research by EPA's Office of Research and Development (ORD). This research is being conducted to identify any potential cross-media transfers of mercury and other metals and to meet EPA's commitment in the Mercury Roadmap (
http://www.epa.gov/hg/roadmap.htm
) to report on the fate of mercury and other metals from implementation of multi-pollutant control at coal-fired power plants.

Over the last few years, in cooperation with Electric Power Research Institute (EPRI) and the utility industry, EPA obtained 73 different CCRs from 31 coal-fired boilers spanning a range of coal types and air pollution control configurations. Samples of CCRs were collected to evaluate differences in air pollution control, such as addition of post-combustion NO
X
controls (
i.e.,
selective catalytic reduction), FGD scrubbers, and enhanced sorbents for mercury capture. A series of reports have been developed to document the results from the ORD research: The first report (Characterization of Mercury-Enriched Coal Combustion Residuals from Electric Utilities Using Enhanced Sorbents for Mercury Control, EPA-600/R-06/008, February 2006;
http://www.epa.gov/ORD/NRMRL/pubs/600r06008/600r06008.pdf
) was developed to document changes in fly ash resulting from the addition of sorbents for enhanced mercury capture. The second report (Characterization of Coal Combustion Residuals from Electric Utilities Using Wet Scrubbers for Multi-Pollutant Control; EPA-600/R-08/077, July 2008,
http://www.epa.gov/nrmrl/pubs/600r08077/600r08077.pdf
) was developed to evaluate residues from the expanded use of wet scrubbers. The third report (Characterization of Coal Combustion Residues from Electric Utilities—Leaching and Characterization Data, EPA-600/R-09/151, December 2009,
http://www.epa.gov/nrmrl/pubs/600r09151/600r09151.html
) updates the data in the earlier reports and provides data on an additional 40 samples to cover the range of coal types and air pollution control configurations, including some not covered in the two previous reports.

Data from these studies is being used to identify potential trends in the composition and leaching behavior of CCRs resulting from changes in air pollution controls. Summary data on the higher volume CCRs is provided for 34 fly ashes (Table 4) and 20 FGD gypsum samples (Table 5). The report provides analysis of other types of CCRs (
i.e.,
non-gypsum scrubber residues (primarily scrubber sludge containing calcium sulfite), blended CCRs (non-gypsum scrubber residues, fly ash, and lime), and wastewater treatment filter cake). For each of the metals that are reported (Sb, As, Ba, B, Cd Cr, Co, Hg, Pb, Mo, Se, and Tl) from the leaching test results, “box and whisker” plots have been developed comparing the different materials and providing comparison to field leachate data.

The purpose of this research was to try to understand how power plant air pollution control residues, and their leaching potential, are likely to change with the increased use of multi-pollutant and mercury controls, anticipated in response to new Clean Air Act regulations. An initial focus was to identify appropriate leach testing methods to assess leaching potential under known or expected CCR management conditions (beneficial use or disposal). The EPA's Science Advisory Board and the National Academy of Sciences have in the past raised concerns over the use of single-point pH tests that do not reflect the range of actual conditions under which wastes are plausibly managed.
9

Because metal leaching rates change with changing environmental conditions (especially pH), single point tests may not be the most accurate predictor of potential environmental release of mercury or other metals because they do not provide estimates of leaching under some disposal or reuse conditions that can plausibly occur.

9
National Academy of Sciences, Managing Coal Combustion Residues in Mines; The National Academies Press, Washington, DC, 2006.

In response to these concerns, a review of available leaching test methods was conducted. A leaching test method
10

based on research conducted at Vanderbilt University in the United States and the Energy Research Center of the Netherlands, among others, was selected to address some of these concerns.

10
Kosson, D.S.; Van Der Sloot, H.A.; Sanchez, F.; Garrabrants, A.C., An Integrated Framework for Evaluating Leaching in Waste Management and Utilization of Secondary Materials. Environmental Engineering Science 2002, 19, 159-204.

While EPA/ORD's research relied on the Vanderbilt method, similar methods (i.e, tests evaluating leaching at different plausible disposal pH values) have been used to evaluate the leaching behavior and support hazardous waste listings of other materials as well.
11

Because of their general utility, the research methods have been drafted into the appropriate format and are being evaluated for inclusion in EPA's waste analytical methods guidance, SW-846
12

to facilitate their routine use for evaluating other wastes or reuse materials (
http://www.epa.gov/osw/hazard/testmethods/sw846/index.htm
).

11

See
65 FR 67100 (November 8, 2000) for a discussion of EPA's use of multi-pH leach testing in support of listing a mercury-bearing sludge from VCM-A production, and EPA/600/R-02/019, September 2001,
Stabilization and Testing of Mercury Containing Wastes: Borden Catalyst.

12
Five different methods have been developed for use depending upon the information needed and the waste form.

1. Draft Method 1313—Liquid-Solid Partitioning as a Function of Eluate pH using a Parallel Batch Extraction Test

2. Draft Method 1314—Liquid-Solid Partitioning as a Function of Liquid-Solid Ratio Using an Up-flow Column Test

3. Draft Method 1315—Mass Transfer in Monolithic or Compacted Granular Materials Using a Semi-dynamic Tank Leach Test

4. Draft Method 1316—Liquid-Solid Partitioning as a Function of Liquid-Solid Ratio Using a Parallel Batch Test

5. Draft Method 1317—Concise Test for Determining Consistency in Leaching Behavior

The test methods were developed to identify differences in the constituent leaching rate resulting from the form of the tested material, as well as the effects of pH and the liquid/solid ratio. Fine grained

materials (e.g., particle sizes of 2 mm or less) will have greater contact with leaching solutions (in a lab test) or rainfall (in the environment) than will solid materials such as concrete or CCRs that are pozzolanic when exposed to water. In applying these methods to CCRs or other materials, batch tests that are designed to reach equilibrium are used with fine-grained or particle-size reduced materials. For solid materials, the tests were designed to evaluate constituent leaching from the exposed surface (leaching of constituents that are either at the surface, or that have migrated over time to the surface), can be used. Testing at equilibrium provides an upper bound estimate of constituent leaching at each set of conditions tested. In some instances, these results may represent the real situation, since when rainfall percolation through a material in the environment is slow, the constituent concentration in the water passing through the materials may reach, or nearly reach equilibrium. Testing of solid (or “monolithic”) materials evaluates constituent leaching from materials of low permeability for which most rainfall flows around the material rather than percolating through it. This results in less contact between the rainfall and the material, and so typically, a lower rate of constituent leaching. For monolithic materials, both the equilibrium and monolith tests are conducted to understand the likely initial rates of leaching from the monolith (while it remains solid), and the upper bound on likely leaching, when the monolith degrades over time, exposing more surface area to percolating rainwater, and typically, higher constituent leaching rates. It may also be possible to avoid the cost of testing solid, monolithic materials, if the material leaches at low constituent concentrations under the equilibrium testing conditions.

For the ORD research, equilibrium batch test methods that identify changes in leaching at different pH and liquid/solid ratio values were used to evaluate CCRs resulting from different air pollution controls at coal-fired power plants. This allowed evaluation of leaching potential over a range of field conditions under which CCRs are anticipated to be managed during either disposal or beneficial use applications. Landfill field leachate data from EPA
13

and EPRI
14

studies were used to establish the range of pH conditions expected to be found in actual disposal. From this data set, and excluding the extreme values (below 5th percentile and above 95th percentile), a pH range of 5.4 and 12.4 was determined to represent the range of plausible management conditions (with regard to pH) for CCRs. This means that approximately 5% of the values had a pH below 5.4 and approximately 5% of the values had a pH greater than 12.4. However, it is important to note that 9 of the 34 fly ash samples generated a pH in deionized water (
i.e.,
the pH generated by the tested material itself) below pH 5.4. Therefore, these results might understate CCR leaching potential if actual field conditions extend beyond the pH range of 5.4 and 12.4.

13
U.S. EPA (2000) Characterization and evaluation of landfill leachate, Draft Report. 68-W6-0068, Sept 2000.

14
EPRI (2006) Characterization of Field Leachates at Coal Combustion Product Management Sites: Arsenic, Selenium, Chromium, and Mercury Speciation, EPRI Report Number 1012578. EPRI, Palo Alto, CA and U.S. Department of Energy, Pittsburgh, PA.

In Tables 4 and 5, the total metals content of the fly ash and FGD gypsum samples evaluated is provided along with the leach test results. Reference indicators (
i.e.,
MCL,
15

TC,
16

and DWEL
17

) are also provided to provide some context in understanding the leach results. It is critical to bear in mind that the leach test results represent a distribution of potential constituent release from the material as disposed or used on the land. The data presented do not include any attempt to estimate the amount of constituent that may reach an aquifer or drinking water well. Leachate leaving a landfill is invariably diluted in ground water to some degree when it reaches the water table, or constituent concentrations are attenuated by sorption and other chemical reactions in groundwater and sediment. Also, groundwater pH may be different from the pH at the site of contaminant release, and so the solubility and mobility of leached contaminants may change when they reach groundwater. None of these dilution or attenuation processes is incorporated into the leaching values presented. That is, no dilution and attenuation factor, or DAF,
18

has been applied to these results. Thus, comparisons with regulatory health values, particularly drinking water values, must be done with caution. Groundwater transport and fate modeling would be needed to generate an assessment of the likely risk that may result from the CCRs represented by these data.

15
MCL is the maximum concentration limit for contaminants in drinking water.

16
TC is the toxicity characteristic and is a threshold for hazardous waste determinations.

17
DWEL is the drinking water equivalent level to be protective for non-carcinogenic endpoints of toxicity over a lifetime of exposure. DWEL was developed for chemicals that have a significant carcinogenic potential and provides the risk manager with evaluation on non-cancer endpoints, but infers that carcinogenicity should be considered the toxic effect of greatest concern (
http://www.epa.gov/safewater/pubs/gloss2.html#D
).

18
For example, EPA used a generic DAF values of 100 in the Toxicity Characteristic final regulation. (
See:
55 FR 11827, March 29, 1990)

In reviewing the data and keeping these caveats in mind, conclusions to date from the research include:

(1) Review of the fly ash and FGD gypsum data (Tables 4 and 5) show a range of total constituent concentration values that vary over a much broader range than do the leach data. This much greater range of leaching values only partially illustrates what more detailed review of the data shows: That for these CCRs, the rate of constituent release to the environment is affected by leaching conditions (in some cases dramatically so), and that leaching evaluation under a single set of conditions may, to the degree that single point leach tests fail to consider actual management conditions, lead to inaccurate conclusions about expected leaching in the field.

(2) Comparison of the ranges of totals values and leachate data from the complete data set supports earlier conclusions 51
19 20 21

that the rate of constituent leaching cannot be reliably estimated based on total constituent concentration alone.

19
Senior, C; Thorneloe, S.; Khan, B.; Goss, D. Fate of Mercury Collected from Air Pollution Control Devices; EM, July 2009, 15-21.

20
U.S. EPA, Characterization of Mercury-Enriched Coal Combustion Residuals from Electric Utilities Using Enhanced Sorbents for Mercury Control, EPA-600/R-06/008, Feb. 2006;
http://www.epa.gov/ORD/NRMRL/pubs/600r06008/600r06008.pdf.

21
U.S. EPA, Characterization of Coal Combustion Residuals from Electric Utilities Using Wet Scrubbers for Multi-Pollutant Control; EPA-600/R-08/077, July 2008,
http://www.epa.gov/nrmrl/pubs/600r08077/600r08077.pdf.

(3) From the more complete data in Report 3, distinctive patterns in leaching behavior have been identified over the range of pH values that would plausibly be encountered for CCR disposal, depending on the type of material sampled and the element. This reinforces the above conclusions based on the summary data.

(4) Based on the data (summarized in Table 4), on the leach results from evaluation of 34 fly ashes across the plausible management pH range of 5.4 to 12.4,

○ The leach results at the upper end of the leachate concentration range exceed the TC values for As, Ba, Cr, and Se (indicated by the shading in the table).

(5) Based on the data (summarized in Table 5), on the leach results from evaluation of 20 FGD gypsums across the plausible management pH range of 5.4 to 12.4,

○ The leach results at the upper end of the leachate concentration ranges exceed the TC value for Se.

(6) The variability in total content and the leaching of constituents within a material type (
e.g.,
fly ash, gypsum) is such that, while leaching of many samples exceeds one or more of the available health indicators, many of the other samples within the material type may be lower than the available regulatory or health indicators.

Additional or more refined assessment of the dataset may allow some distinctions regarding release potential to be made among particular sources of some CCRs, which may be particularly useful in evaluating CCRs in reuse applications.

EPA anticipates development of a fourth report that presents such additional analysis of the leaching data to provide more insight into constituent release potential for a wider range of CCR management scenarios, including beneficial use applications. This will include calculating potential release rates over a specified time for a range of management scenarios, including use in engineering and commercial applications using probabilistic assessment modeling (Sanchez and Kosson, 2005).
22

This report will be made publicly available when completed.

22
Sanchez, F., and D. S. Kosson, 2005. Probabilistic approach for estimating the release of contaminants under field management scenarios.
Waste Management
25(5), 643-472 (2005).

Finally, the Agency recognizes that this research has generated a substantial amount of data, and believes this data set can be useful as a reference for assessing additional CCR samples in the future. The docket for today's rule therefore includes the full dataset, in the form of a database to provide easier access to EPA's updated leach data.
23

23
The database, called “Leach XS Lite” can be used to estimate the leaching potential of CCRs under any specified set of pH or infiltration conditions that may occur in the field. While the database is presented as a “Beta” version, and may be further developed, the data presented in the data base are final data, from the three EPA research reports cited above.

EP21JN10.000

Note:

The dark shading is used to indicate where there could be a potential concern for a metal when comparing the leach results to the MCL, DWEL, or concentration level used to determine the TC. Note that MCL and DWEL values are intended to represent concentrations at a well and the point of exposure; leachate dilution and attenuation processes that would occur in groundwater before leachate reaches a well are not accounted for, and so MCL and DWEL values cannot be directly compared with leachate values.

EP21JN10.001

Note:

The dark shading is used to indicate where there could be a potential concern for a metal when comparing the leach results to the MCL, DWEL, or concentration level used to determine the TC. Note that MCL and DWEL values are intended to represent concentrations at a well and the point of exposure; leachate dilution and attenuation processes that would occur in groundwater before leachate reaches a well are not accounted for, and so MCL and DWEL values cannot be directly compared with leachate values.

G. Current Federal Regulations or Standards Applicable to the Placement of CCRs in Landfills and Surface Impoundments.

CCR disposal operations are typically regulated by state solid waste management programs, although in some instances, surface impoundments are regulated under the states water programs. However, there are limited regulations of CCRs at the federal level.

The discharge of pollutants from CCR management units to waters of the United States are regulated under the National Pollutant Discharge Elimination System (NPDES) at 40 CFR Part 122, authorized by the Clean Water Act (CWA). NPDES permits generally specify an acceptable level of a pollutant or pollutant parameter in a discharge. NPDES permits ensure that a state's mandatory standards for clean water and the federal minimums are being met. A number of the damage cases discussed in the preamble also involved surface water contamination, which were violations of the NPDES permit requirements.

II. New Information on the Placement of CCRs in Landfills and Surface Impoundments

A. New Developments Since the May 2000 Regulatory Determination.

Since publication of the May 2000 Regulatory Determination, new information and data have become available, including additional damage cases, risk modeling, updated information on current management practices and state regulations associated with the disposal of CCRs, petitions from environmental and citizens groups for EPA to develop rules for the management of CCRs, an industry voluntary agreement on how they would manage CCRs, and a proposal from environmental and citizens groups for a CCR rule. Much of this new information was made available to the public in August 2007 through a Notice of Data Availability (NODA) at 72 FR 49714 (
http://www.epa.gov/fedrgstr/EPA-WASTE/2007/August/Day-29/f17138.pdf
). EPA has received extensive comments from environmental groups, industry, states and others in response to the NODA and as we have moved toward rulemaking. All of the comments and subsequent information we have received are included in the docket to this proposal. The new information on risks and the damage cases are discussed briefly below and in more detail in subsequent sections of this proposed rule; a more detailed discussion of this new information is discussed in other sections of the preamble.

At the time of the May 2000 Regulatory Determination, the Agency was aware of 14 cases of proven damages
24

and 36 cases of potential damages resulting from the disposal of

CCRs. The Agency has since learned of an additional 13 cases of proven damages and 4 cases of potential damages, including a catastrophic release of CCRs from a disposal unit at the Tennessee Valley Authority (TVA) Kingston facility in Harriman, Tennessee in December 2008. In total, EPA has documented 27 cases of proven damages and 40 cases of potential damages resulting from the disposal of CCRs. Proven damage cases have been documented in 12 states, and potential damage cases—in 17 states.
See
section II.C. and the Appendix to this proposal for more detailed discussions of EPA's CCR damage cases.

24
As discussed later in the preamble, 11 of these documented cases of damage were to human health and the environment, while four of these cases were cases of ecological damage, one of which has now been reclassified as a potential damage case.

As part of the process for making the May 2000 Regulatory Determination for CCRs, EPA prepared a draft quantitative risk assessment. However, because of time constraints, the Agency was unable to address public comments on the draft risk assessment in time for the Regulatory Determination. Between 2000 and 2006, EPA addressed the public comments and updated the quantitative risk assessment for the management of CCR in landfills and surface impoundments. The revised risk assessment was made available for public comment in the August 2007 draft report titled “Human and Ecological Risk Assessment of Coal Combustion Wastes.”

In the May 2000 Regulatory Determination, the Agency concluded that the utility industry had made significant improvements in its waste management practices for new landfills and surface impoundments since the practices reflected in the 1999 Report to Congress, and that most state regulatory programs had similarly improved. To verify its conclusion, in 2005, the U.S. Department of Energy (DOE) and EPA conducted a joint study to collect more recent information on the management practices for CCRs by the electric power industry, and state programs in 11 states. The results of the study were published in the report titled “Coal Combustion Waste Management at Landfills and Surface Impoundments, 1994-2004.” Additionally, we are aware of at least one state (Maryland) that has recently amended its regulatory requirements for the management of CCRs.

In February 2004, 125 environmental and citizens groups petitioned the EPA Administrator for a rulemaking prohibiting the disposal of coal power plant wastes into groundwater and surface water until such time as EPA promulgates federally enforceable regulations pursuant to RCRA. A copy of the petition is available at
http://www.regulations.gov/fdmspublic/component/main?/main=DocumentDetail&o=09000064801cf8d1.

In October 2006, the utility industry through their trade association, the Utility Solid Waste Activities Group (USWAG) submitted to EPA a “Utility Industry Action Plan for the Management of Coal Combustion Products.” The plan outlines the utility industry's commitment to adopt groundwater performance standards and monitoring, conduct risk assessments prior to placement of CCRs in sand and gravel pits, and to consider dry-handling prior to constructing new disposal units.

In January 2007, environmental and citizens groups submitted to EPA a “Proposal for the Federal Regulation of Coal Combustion Waste.” The proposal provides a framework for comprehensive regulation under subtitle D of RCRA for waste disposed of in landfills and surface impoundments generated by coal-fired power plants. Then in July 2009, environmental and citizens groups filed a second petition requesting that the EPA Administrator promulgate regulations that designate CCRs as hazardous waste under subtitle C of RCRA.
25

In support of their petition, the environmental groups cited “numerous reports and data produced by the Agency since EPA's final Regulatory Determination * * * which quantify the waste's toxicity, threat to human health and the environment, inadequate state regulatory programs, and the damage caused by mismanagement.” A copy of the petition is available in the docket to this proposal. The Agency has, as yet, not made a decision as to whether to lift the Bevill exemption, and, while it has determined that federal regulation is appropriate, it has not made a determination as to whether regulations should be promulgated under subtitles C or D of RCRA. Consequently, EPA is deferring its response to the petitioner. However, the preamble discusses the issues raised in these petitions at length. In addition, the Agency is deferring its proposed response to the petitioners' request regarding the placement of CCRs in minefills as the Agency will work with OSM to address the management of CCRs in minefills in a separate rulemaking action. (
See
discussion in other parts of the preamble for the Agency's basis for its decisions.)

25
This rulemaking petition was filed by: Earthjustice; the Sierra Club; the Environmental Integrity Project; the Natural Resources Defense Council; the Southern Environmental Law Center; and Kentucky Resources Council.

In August 2007, EPA published a NODA (72 FR 49714,
http://www.epa.gov/fedrgstr/EPA-WASTE/2007/August/Day-29/f17138.htm
) which made public, and sought comment on, the new information we received since the May 2000 Regulatory Determination through 2007, except for the July 2009 petition entitled,
Petition for Rulemaking Pursuant to Section 7004(a) of the Resource Conservation and Recovery Act Concerning the Regulation of Coal Combustion Waste and the Basis for Reconsideration of the 2000 Regulatory Determination Concerning Wastes from the Combustion of Fossil Fuels.
The new information included the joint DOE and EPA report entitled:
Coal Combustion Waste Management at Landfills and Surface Impoundments, 1994-2004;
the draft risk assessment; and EPA's damage case assessment. EPA also included in the docket to the NODA the February 2004 Petition for Rulemaking submitted by a number of environmental and citizens' groups to prohibit the placement or disposal of CCRs into ground water and surface water; and two suggested approaches for managing CCRs in landfills and surface impoundments. One approach is the Voluntary Action Plan that was formulated by the electric utility industry. The second approach was the January 2007 framework prepared by a number of environmental and citizens' groups proposing federal regulation under subtitle D of RCRA for CCRs generated by U.S. coal-fired power plants and disposed of in landfills and surface impoundments. The Agency received a total of 396 comments on the NODA from 375 citizens and citizen and environmental groups, 16 industry groups, and 5 state and local government organizations. In general, citizens, citizens groups, and environmental groups commented that state regulations are inadequate and called on EPA to develop enforceable regulations for the disposal of CCRs under the hazardous waste provisions of RCRA. Industry groups, on the other hand, stated that the significant recent improvement in industry management and state regulatory oversight of CCR disposal demonstrates that the conditions that once led EPA to determine that federal subtitle D regulations were warranted no longer exist and therefore, further development of subtitle D regulations is no longer necessary. In September 2008, the Environmental Council of the States (ECOS) issued a resolution that states already have regulations in place that apply to CCRs, and a federal regulation is not necessary. The 2008 ECOS resolution was revised in March 2010 and calls upon EPA to conclude that

additional federal CCR regulations would be duplicative of most state programs, are unnecessary, and should not be adopted, but if adopted must be developed under RCRA subtitle D rather than RCRA subtitle C (
see http://www.ecos.org/files/4018_file_Resolution_08_14_2010_version.doc
). Comments on the NODA are available in the docket to the NODA at
http://www.regulations.gov,
docket number EPA-HQ-RCRA-2006-0796.

Finally, in July and August of 2008, EPA conducted a peer review of the 2007 draft risk assessment “Human and Ecological Risk Assessment of Coal Combustion Wastes.” The peer review was conducted by a team of five experts in groundwater modeling, environmental fate and transport modeling, and human health and ecological risk assessment. EPA has revised its risk assessment based on the peer review comments. Results of the peer review and the revised risk assessment are included in the docket to this proposal. Also,
see
section II.B. below and the document titled “What Are the Environmental and Health Effects Associated with Disposing of CCRs in Landfills and Surface Impoundments?” available from the docket to this notice for more detailed discussions of the risk assessment.

In summary, since the May 2000 Regulatory Determination, the Agency has (1) Documented an additional 17 cases of damage from the disposal of CCRs (13 proven and 3 potential); (2) gathered additional information on industry practices; (3) revised its risk assessment, based on comments received on the 1999 Report to Congress, conducted a peer review of the revised risk assessment, and further revised its risk assessment based on peer review comments and comments received on the August 2007 NODA; (4) received a voluntary action plan from the utility industry; (5) received two petitions for rulemaking from environmental and citizens groups; and (6) received a proposal for regulating the management of CCRs in landfills and surface impoundments from environmental and citizens groups. EPA has considered all of this information in making the decisions on the proposals in this notice.

B. CCR Risk Assessment

In making the May 2000 Regulatory Determination for CCRs, EPA prepared a draft quantitative risk assessment based on groundwater modeling. However, commenters from all sides raised fundamental scientific questions with the study, and raised issues that went beyond groundwater modeling capability at the time. EPA was unable to address these issues in the available time, and therefore did not rely on the draft risk assessment as part of its basis in making its May 2000 Regulatory Determination; rather we relied on the damage cases identified, as well as other information. In this regard, it is worth noting that EPA did not conclude that the available information regarding the extent or nature of the risks were equivocal. Rather, EPA noted that we had not definitively assessed the ground water risks, due to the criticisms of our draft risk assessment, but still concluded that there were “risks from arsenic that we cannot dismiss.” Largely what drove the risks in the original risk assessment were the old units that lacked liners and ground water monitoring (for landfills, only 57% of the units had liners and 85% of the units had ground water monitoring, while for surface impoundments, only 26% of the units had liners and only 38% of the units had ground water monitoring).

Between 2000 and 2006, EPA addressed public comments and updated the quantitative risk assessment for the management of CCRs in landfills and surface impoundments. The purpose of the risk assessment is to identify CCR constituents, waste types, liner types, receptors, and exposure pathways with potential risks and to provide information that EPA can use as we continue to evaluate the risks posed by CCRs disposed of in landfills and surface impoundments. The risk assessment was designed to develop national human and ecological risk estimates that are representative of onsite CCR management settings throughout the United States. A revised draft risk assessment was made available to the public through the August 2007 NODA (which is discussed in other sections of the preamble) and is available at
http://www.regulations.gov/fdmspublic/component/main?main=DocumentDetail&o=090000648027b9cc
.

EPA submitted the revised draft risk assessment report, together with public comments on the report in response to the 2007 NODA, to a peer review panel. EPA completed the risk assessment, taking into account peer review comments, in a final report titled “Human and Ecological Risk Assessment of Coal Combustion Wastes,” (September 2009). The report, peer review comments, and EPA's response to the peer review comments are available in the docket for this proposal.

For purposes of this rulemaking, EPA defined the target level of protection for human health to be an incremental lifetime cancer risk of no greater than one in 100,000 (10
−5
) for carcinogenic chemicals and a hazard quotient of 1.0 for noncarcinogenic chemicals. The hazard quotient is the ratio of an individual's chronic daily dose of a constituent to the reference dose for that constituent, where the reference dose is an estimate of the daily dose that is likely to be without appreciable risk of deleterious effects over a lifetime. These are the target levels that EPA typically uses in its listing decisions. (
See,
for example, the final rule for Nonwastewaters From Productions of Dyes, Pigments, and Food, Drug, and Cosmetic Colorants (70 FR 9144) at
http://www.epa.gov/wastes/laws-regs/state/revision/frs/fr206.pdf
.)

The results of this risk assessment provide further confirmation of the high risks presented in the mismanagement of CCRs disposed in landfills and surface impoundments. The assessment does confirm that there are methods to manage CCRs safely, although it calls into question the reliability of clay liners, especially in surface impoundments, and it points to very high potential risks from unlined surface impoundments.

Specifically, the revised draft CCR risk assessment presents results at a typical exposure (50th percentile), as well as a high-end exposure (90th percentile) risk based on a probabilistic analysis. The revised draft CCR risk assessment results at the 90th percentile suggest that the management of CCRs in unlined or clay-lined waste management units (WMUs) result in risks greater than the risk criteria of 10
−5
for excess cancer risk to humans or an HQ greater than 1 for noncancer effects to both human and ecological receptors which are the criteria generally used in EPA's listing determination procedure.
26

While still above the criteria, clay-lined units tended to have lower risks than unlined units. However, it was the composite-lined units that effectively reduced risks from all pathways and constituents below the risk criteria. More specifically:

26
EPA's hazardous waste listing determination policy is described in the notice of proposed rulemaking for wastes from the dye and pigment industries at 59 FR 66075-66077
available at http://www.epa.gov/fedrgstr/EPA-WASTE/1994/December/Day-22/pr-98.html
and in the final rule for Nonwastewaters From Productions of Dyes, Pigments, and Food, Drug, and Cosmetic Colorants (70 FR 9144) at
http://www.epa.gov/wastes/laws-regs/state/revision/frs/fr206.pdf
.

○ For humans exposed via the groundwater-to-drinking-water pathway, estimated risks from clay-lined landfills that dispose of CCRs or

CCRs co-managed with coal refuse are lower than those for unlined landfills. However, the 90th percentile risk estimates, for arsenic that leaks from clay-lined landfills are still above the risk criteria—as high as 1 in 5,000 individual lifetime excess cancer risk.
27

When landfills are unlined, estimated risks above the criteria occur for antimony and molybdenum, as well as arsenic (as high as 1 in 2,000 individual lifetime excess cancer risk). In addition to arsenic, clay-lined fluidized bed combustion (FBC) landfills also presented estimated 90th percentile risks above the criteria for antimony. However, unlined FBC landfills differed in that they were estimated to exceed the risk criteria only for arsenic.
28

At the 50th percentile, only trivalent arsenic from CCRs codisposed with coal refuse was estimated to exceed the risk criteria with cancer risks of 1 in 50,000.

27
Excess cancer risk means risk in addition to pre-existing, “background” risk from other exposures.

28
Unlined FBC landfills showed less risk as modeled; note that the number of FBC landfills modeled was very small (seven).

○ Arsenic and cobalt were the constituents with the highest estimated risks for surface impoundments. Clay-lined surface impoundments were estimated to present 90th percentile risks above the criteria for arsenic, boron, cadmium, cobalt, molybdenum, and nitrate. The 90th percentile clay-lined impoundment estimated risks and hazard quotients (HQs) were as follows: for arsenic, the estimated risk was as high as 1 in 140; cobalt's estimated HQ as high as 200, while the estimated HQs for boron, cadmium, molybdenum and nitrate ranged from 2 to 20. The 90th percentile unlined surface impoundment estimates were above the criteria for constituents that include arsenic, lead, cobalt and selenium: estimated arsenic cancer risks are as high as 1 in 50, and non-cancer effects estimates for cobalt ranged from an estimated HQ of 0.9 to 500 depending on whether CCRs were co-managed with coal refuse. At the 50th percentile, the only surface impoundment results estimated to exceed the risk criteria were arsenic and cobalt: unlined impoundments had estimated arsenic cancer risks as high as 6 in 10,000, while clay-lined impoundments had estimated arsenic cancer risks as high as 1 in 5,000. The 50th percentile noncancer HQs due to cobalt in drinking water were estimated to be as high as 20 and 6 for unlined and clay-lined surface impoundments, respectively.

○ Composite liners, as modeled in this assessment, effectively reduce risks from all constituents to below the risk criteria for both landfills and surface impoundments at the 90th and 50th percentiles.

○ The model generally predicts that groundwater risks will occur centuries later for landfills than for surface impoundments. For the groundwater-to-drinking water pathway for unlined landfills, arrival times of the peak concentrations at a receptor well peaked in the hundreds or thousands of years, while unlined surface impoundment risks typically peaked within the first 100 years. Clay liners resulted in later arrival of peak risks, nearly always in the thousands of years for landfills but still in the first few hundred years for surface impoundments. Finally, while composite liners often resulted in a failure of the plume to reach groundwater wells, composite-lined landfills with plumes that were estimated to reach groundwater wells eventually had peak arsenic-in-groundwater concentrations at approximately 10,000 years, while composite-lined surface impoundments' plumes peaked in the thousands of years.

○ For humans exposed via the groundwater-to-surface-water (fish consumption) pathway, unlined and clay-lined surface impoundments were estimated to pose risks above the criteria at the 90th percentile. For CCRs managed alone in surface impoundments, these exceedances came from selenium (estimated HQs of 3 and 2 for unlined and clay-lined units, respectively). For CCRs co-managed with coal refuse, these exceedences came from arsenic (3 in 100,000 and 2 in 100,000 estimated excess cancer risks for unlined and clay-lined units, respectively). All 50th percentile surface impoundment risks are estimated to be below the risk criteria. No constituents pose estimated risks above the risk criteria for landfills (including FBC landfills) at the 90th or 50th percentile.

○ EPA also conducted a separate draft fugitive dust screening assessment which indicates that, without fugitive dust controls, there could be exceedances of the National Ambient Air Quality Standards for fine particulate matter in the air at residences near CCR landfills.
29

The 1998 risk assessment
30

also showed risks from inhalation of chromium in fugitive dust but at levels below the criteria.
31

29
EPA's decision to address fugitive dust was based on a peer review comment to the draft Risk Assessment, stakeholder NODA comments, photographic documentation of fugitive dust associated with the hauling and disposal of CCRs, Agency efforts to control fugitive dust emissions from the TVA Kingston spill (see e.g.,
http://www.epakingstontva.com/EPA%20Air%20Audits%20and%20Reviews/Kingston%20Fly%20Ash%20-%20EPA%20Audit.pdf
), and OSHA's requirement for MSDS sheets for coal ash.

30
Non-Groundwater Pathways, Human Health and Ecological Risk Analysis for Fossil Fuel Combustion Phase 2 (FFC2): Draft Final Report (
http://www.epa.gov/osw/nonhaz/industrial/special/fossil/ngwrsk1.pdf
).

31
All chromium present in the particulate matter was assumed to be in the more toxic, hexavalent form.

EPA recognizes that there are significant uncertainties in national risk assessments of this nature, although it did attempt to address potential uncertainties through Monte Carlo and sensitivity analyses. Uncertainties discussed in the revised risk assessment include:

• The locations and characteristics of currently operating facilities;

• The failure to account for direct discharges to surface water;

• Changing conditions over the 10,000-year period modeled;

• Shifting populations and ecological receptors;

• Additive risks from multiple constituents or multiple pathways;

• Clean closure of surface impoundments;

• The speciation and bioavailability of constituents;

• The effect of compacting CCRs before disposal;

• The assumption that all disposal units are above the water table;

• Full mixing of the groundwater plume;

• The choice of iron sorbent in the soil;

• The appropriateness of the leachate data used and the treatment of nondetects;

• The distance to receptor wells and surface water bodies; and

• The potential conservativeness of human health benchmarks.

The Agency, however, does solicit comment on several specific aspects of the underlying risk assessment. In particular, EPA requests comment on whether clay liners designed to meet a 1x10
−7
cm/sec hydraulic conductivity might perform differently in practice than modeled in the risk assessment. Thus, EPA solicits specific data on the hydraulic conductivity of clay liners associated with CCR disposal units. In addition to the effectiveness of various liner systems, the hydraulic conductivity of coal ash can be reduced with the appropriate addition of moisture followed by compaction to attain 95% of the standard Proctor

maximum dry density value.
32

This concept, it has been reported, could potentially be taken further with the use of compaction coupled with the addition of organosilanes. According to recent studies, organosilanes could take the hydraulic conductivity to zero.
33

EPA solicits comments on the effectiveness of such additives, including any analysis that would reflect long-term performance, as well as the appropriateness of a performance standard that would allow such control measures in lieu of composite liners. EPA has also observed that surface impoundments

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2010-12286. Public record. Not legal advice.
