Document ID: EPA-HQ-OLEM-2019-0173-0202
Agency: epa
Document Type: Rule
Title: Hazardous and Solid Waste Management System: Disposal of Coal Combustion Residuals; A Holistic Approach to Closure Part B, Alternate Demonstration for Unlined Surface Impoundments
Posted Date: 2020-11-12T05:00Z

[Federal Register Volume 85, Number 219 (Thursday, November 12, 2020)]
[Rules and Regulations]
[Pages 72506-72543]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-23327]

[[Page 72505]]

Vol. 85

Thursday,

No. 219

November 12, 2020

Part VII

Environmental Protection Agency

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40 CFR Part 257

Hazardous and Solid Waste Management System: Disposal of CCR; A 
Holistic Approach to Closure Part B: Alternate Demonstration for 
Unlined Surface Impoundments; Final Rule

  Federal Register / Vol. 85 , No. 219 / Thursday, November 12, 2020 / 
Rules and Regulations  

[[Page 72506]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 257

[EPA-HQ-OLEM-2019-0173; FRL-10015-88-OLEM]
RIN 2050-AH11

Hazardous and Solid Waste Management System: Disposal of CCR; A 
Holistic Approach to Closure Part B: Alternate Demonstration for 
Unlined Surface Impoundments

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: On April 17, 2015, the Environmental Protection Agency (EPA or 
the Agency) promulgated national minimum criteria for existing and new 
coal combustion residuals (CCR) landfills and existing and new CCR 
surface impoundments. On August 21, 2018, the U.S. Court of Appeals for 
the D.C. Circuit issued its opinion in the case of Utility Solid Waste 
Activities Group v. EPA, 901 F.3d 414 (per curiam) (USWAG). This rule 
finalizes regulations proposed on March 3, 2020, including procedures 
to allow facilities to request approval to operate an existing CCR 
surface impoundment with an alternate liner, among other things. 
Provisions from the proposed rule that are not addressed in this rule 
will be addressed in a subsequent action.

DATES: This final rule is effective on December 14, 2020.

ADDRESSES: EPA has established a docket for this action under Docket 
ID. No. EPA-HQ-OLEM-2019-0173. All documents in the docket are listed 
on the http://www.regulations.gov website. 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, is not placed on the internet 
and will be publicly available only in hard copy form. Publicly 
available docket materials are available electronically through http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: Michelle Long, Office of Resource 
Conservation and Recovery, Materials Recovery and Waste Management 
Division, Environmental Protection Agency, 1200 Pennsylvania Avenue NW, 
MC: 5304P, Washington, DC 20460; telephone number: (703) 347-8953; 
email address: Long.Michelle@epa.gov. For more information on this 
rulemaking, please visit https://www.epa.gov/coalash.

SUPPLEMENTARY INFORMATION: 

Table of Contents

I. General Information
    A. Does this action apply to me?
    B. What action is the Agency taking?
    C. What is EPA's authority for taking this action?
    D. What are the incremental costs and benefits of this action?
II. Background
    A. The ``2015 CCR Rule''
    B. The 2018 USWAG Decision
    C. The March 2020 Proposed Rule
    D. Public Participation on the Proposed Rule
III. Addition of Sec.  257.71(d) To Allow for Alternate Liner 
Demonstrations
    A. Factual Basis
    B. Application
    C. Alternate Liner Demonstration
    D. Procedures for Approval and Denial of Alternate Liner 
Demonstration
IV. Corrections to Sec. Sec.  257.102 and 257.103
V. Rationale for 30-Day Effective Date
VI. Effect of This Final Rule on States With Approved CCR Programs
VII. The Projected Economic Impacts of This Action
    A. Introduction
    B. Affected Universe
    C. Costs, Cost Savings, and Benefits of the Final Rule
VII. Executive Orders
Regulatory Text

I. General Information

A. Does this action apply to me?

    This rule applies to all CCR generated by electric utilities and 
independent power producers that fall within the North American 
Industry Classification System (NAICS) code 221112 and may affect the 
following entities: electric utility facilities and independent power 
producers that fall under the NAICS code 221112. This discussion is not 
intended to be exhaustive, but rather provides a guide for readers 
regarding entities likely to be regulated by this action. This 
discussion lists the types of entities that EPA is now aware could 
potentially be regulated by this action. Other types of entities not 
described here could also be regulated. To determine whether your 
entity is regulated by this action, you should carefully examine the 
applicability criteria found in Sec.  257.50 of title 40 of the Code of 
Federal Regulations. If you have questions regarding the applicability 
of this action to a particular entity, consult the person listed in the 
FOR FURTHER INFORMATION CONTACT section.

B. What action is the Agency taking?

    EPA is revising certain provisions of the CCR regulations at 40 CFR 
part 257 in response to the decision issued by the D.C. Circuit on 
August 21, 2018, in Utility Solid Waste Activities Group v. EPA 901 
F.3d 414 (D.C. Cir.). Specifically, the Agency is finalizing a revision 
to the 2015 CCR Rule that provides procedures for facilities to request 
approval to use an alternate liner for CCR surface impoundments.
    EPA is finalizing a two-step process for submittal of the necessary 
documentation for the alternate liner demonstration. The first step 
consists of an initial application intended to show whether a unit 
meets certain minimum requirements before embarking on a comprehensive 
alternate liner demonstration. These minimum requirements are designed 
to ensure that it is likely that the facility will ultimately be able 
to make the more extensive demonstration to support continued 
operation, and that the CCR surface impoundment can operate safely over 
the short term while the facility collects the data and conducts the 
analyses necessary to support the demonstration. The first step 
requires the facility to demonstrate that it is in full compliance with 
the applicable requirements in 40 CFR part 257 subpart D; that it 
possesses site characteristics that make it likely that it could 
qualify for a demonstration; and that there are no constituents listed 
in part 257 Appendix III that have been detected at a statistically 
significant increase (SSI) above background. The second step consists 
of a final demonstration intended to show whether there is a reasonable 
probability that releases from the impoundment throughout its active 
life may result in groundwater concentrations of constituents listed in 
part 257 Appendix IV at a statistically significant level (SSL) in the 
future. The purpose of this two-step approach is to ensure that units 
allowed to embark on a comprehensive and time-consuming demonstration 
meet the minimum requirements to ensure protectiveness throughout the 
process.
    Provisions from the proposed rule that are not addressed in this 
rule will be addressed in a subsequent rulemaking action. The remaining 
provisions from the proposed rule are to allow the use of CCR during 
closure of a CCR unit, to establish an additional closure option for 
CCR units being closed by removal of CCR, and to establish requirements 
for annual closure progress reports.
    EPA intends that the provisions of this rule be severable. In the 
event that any individual provision or part of this rule is 
invalidated, EPA intends that this would not render the entire rule 
invalid, and that any individual provisions that can continue to 
operate will be left in place.

[[Page 72507]]

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

    These regulations are established under the authority of sections 
1008(a), 2002(a), 4004, and 4005(a) and (d) 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) and the Water Infrastructure Improvements for the Nation 
(WIIN) Act of 2016, 42 U.S.C. 6907(a), 6912(a), 6944, and 6945(a) and 
(d).

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

    This action is expected to result in an estimated annualized net 
cost savings of approximately $4.0 million per year to $8.0 million per 
year when discounting at 7% and approximately $2.2 million per year to 
$4.5 million per year when discounting at 3%. Further information on 
the economic effects of this action can be found in Unit VII of this 
preamble.

II. Background

A. The ``2015 CCR Rule''

    On April 17, 2015, EPA finalized national minimum criteria for the 
disposal of CCR as a solid waste under Subtitle D of RCRA. 80 FR 21302. 
The Agency refers to the April 17, 2015 rule as the ``2015 CCR Rule'' 
in this preamble. CCR are generated from the combustion of coal by 
electric utilities and independent power producers for the generation 
of electricity. CCR include fly ash, bottom ash, boiler slag, and flue 
gas desulfurization materials and are commonly referred to as coal ash. 
The CCR regulations are codified in subpart D of part 257 of title 40 
of the CFR.
    The 2015 CCR Rule regulated existing and new CCR landfills and 
existing and new CCR surface impoundments, as well as all lateral 
expansions of these CCR units. The federal national minimum criteria 
consist of location restrictions (siting limitations), design and 
operating criteria, groundwater monitoring and corrective action 
requirements, and closure and post-closure care requirements. In 
addition, the 2015 CCR Rule put in place recordkeeping, notification, 
and internet posting provisions that require owners and operators of 
CCR units to maintain a publicly accessible internet site of rule 
compliance information. The 2015 CCR Rule does not regulate CCR that 
are beneficially used. It established a definition of ``beneficial use 
of CCR'' to distinguish between beneficial use and disposal.
    Of particular relevance to this action, the 2015 CCR Rule required 
that any existing unlined CCR surface impoundment that cause 
groundwater concentrations to exceed a groundwater protection standard 
(GWPS) must stop receiving waste (CCR and/or non-CCR wastestreams) 
within six months of making an exceedance determination. This would 
also trigger the requirement to initiate either unit retrofit or 
closure activities.\1\ See Sec.  257.101(a)(1) at 80 FR 21490 (April 
17, 2015). In the 2015 CCR Rule, the term ``unlined'' CCR surface 
impoundment included any unit not constructed with one of the following 
types of liners: (1) A composite liner; (2) an alternative composite 
liner; or (3) a liner consisting of a minimum of two feet of compacted 
soil with a hydraulic conductivity of no more than 1 x 
10-\7\ centimeters per second. Lined CCR surface 
impoundments (as defined in the CCR regulations) that impact 
groundwater above the specified GWPS are not required to close and 
could continue to operate while corrective action is performed, and the 
source of the groundwater contamination is addressed.
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    \1\ Certain units may be eligible for the alternative closure 
procedures specified in Sec.  257.103 which would change the date by 
which the unit must stop receiving waste.
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    The 2015 CCR Rule was challenged by several parties, including a 
coalition of regulated entities and a coalition of environmental 
organizations (``Environmental Petitioners''). See USWAG v EPA, 901 
F.3d 414 (DC Cir. 2018). The Environmental Petitioners raised two 
challenges \2\ that are relevant to this final rule. First, they 
challenged the provision that allowed existing, unlined CCR surface 
impoundments to continue to operate until they cause groundwater 
contamination. See Sec.  257.101(a)(1) at 80 FR 21490 (April 17, 2015). 
They contended that EPA failed to show how continued operation of 
unlined impoundments met RCRA's baseline requirement that any solid 
waste disposal site pose ``no reasonable probability of adverse effects 
on health or the environment.'' See 42 U.S.C. 6944(a). The 
Environmental Petitioners also challenged the provisions that allowed 
impoundments lined with two feet of clay (i.e., compacted soil) to 
continue operating even when they leak, requiring only that they 
remediate the resulting contamination. The petitioners pointed to 
record evidence that ``clay-lined'' units are likely to leak and 
contended that EPA's approach ``authorizes an endless cycle of spills 
and clean-ups'' in violation of RCRA.
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    \2\ Environmental Petitioners also challenged the provisions 
exempting inactive surface impoundments at inactive power plants 
from regulation. The Court ruled for the Petitioners on these 
claims, vacating these provisions and remanding to EPA. However, in 
contrast to the other provisions addressed in this rule, additional 
rulemaking is necessary to effectuate the Court's order, as the 
Court's vacatur alone did not subject these units to regulation. 
This aspect of the decision will be addressed in a subsequent 
proposal.
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B. The 2018 USWAG Decision

    The D.C. Circuit issued its decision on USWAG v. EPA on August 21, 
2018. The Court upheld most of the 2015 CCR Rule but ruled for the 
Environmental Petitioners on the two claims discussed in Unit II.A of 
this preamble. The Court held that EPA acted ``arbitrarily and 
capriciously and contrary to RCRA'' in failing to require the closure 
of unlined surface impoundments and in classifying so-called ``clay-
lined'' impoundments as lined, based on the record supporting the rule. 
901 F.3d at 431-432. The Court ordered that ``the Final Rule be vacated 
and remanded with respect to the provisions that permit unlined 
impoundments to continue receiving coal ash unless they leak, Sec.  
257.101(a), [and] classify `clay-lined' impoundments as lined, see 40 
CFR 257.71(a)(1)(i).'' Id. The Court issued the mandate for this 
decision on October 15, 2018. This decision is referred to as the 
``USWAG decision'' in this action.

C. The March 2020 Proposed Rule

    In the March 3, 2020 rule, EPA proposed revisions to the 2015 CCR 
Rule, including: Procedures to allow facilities to request approval to 
use an alternate liner for CCR surface impoundments; two co-proposed 
options to allow the use of CCR during unit closure; an additional 
closure option for CCR units being closed by removal of CCR; and 
requirements for annual closure progress reports. In this final rule, 
the Agency is taking final action on the proposed procedures for 
facilities to request approval to use an alternate liner for CCR 
surface impoundments. Provisions from the proposed rule that are not 
addressed in this rule will be addressed in a subsequent action.

D. Public Participation on the Proposed Rule

    The Agency received over 42,000 comments on the proposed rule, with 
over 170 unique comments. The majority of commenters focused on the 
alternate liner demonstration (ALD) provisions, as well as use of CCR 
in closure. Commenters included individual electric utilities and 
independent power producers, national trade associations, state 
agencies, public

[[Page 72508]]

interest and environmental groups, and entities involved with the 
beneficial use of CCR. All public comments submitted in response to the 
proposal can be found in the docket for this action. EPA's responses to 
comments on the proposed rule are addressed either in this preamble or 
in the response to comment document available in the docket to this 
final rule.
    EPA conducted two virtual public hearings on April 7, 2020, and 
April 9, 2020 using an internet-based software platform. The platform 
allowed hearing participants to provide oral testimony using a 
microphone and speakers connected to their computers or using a phone. 
It provided the ability for any person to listen to the public hearing 
via their computer. On April 7, 2020, there were 38 speakers and a 
total of 142 registered attendees. On April 9, 2020, there were 30 
speakers and a total of 82 registered attendees. Testimony at the 
public hearing focused generally on the proposed amendments of allowing 
the use of alternate liner demonstrations and use of CCR in closure. 
Several speakers commented on the alternate liner demonstration or the 
use of CCR in closure to allow CCR to be disposed in unlined surface 
impoundments indefinitely and contaminating groundwater, and the 
overall risks, especially health risks, related to CCR. Many speakers 
advocated for strengthening of the regulations rather than finalizing 
``rollbacks.'' Many commenters were concerned that people were unable 
to attend the public hearing because of the COVID-19 pandemic, and that 
EPA did not extend the public comment period. Transcripts for both 
virtual public hearings are included in the docket for this action.

III. Addition of Sec.  257.71(d) To Allow for Alternate Liner 
Demonstrations

    The 2015 CCR Rule required that all existing unlined CCR surface 
impoundments that caused groundwater concentrations to exceed 
associated GWPS must stop receiving waste and either retrofit or close. 
In the 2015 CCR Rule, the term ``unlined'' CCR surface impoundment 
included any unit not constructed with one of the following types of 
liners: (1) Composite liner; (2) alternative composite liner; or (3) 
liner consisting of a minimum of two feet of compacted soil with a 
hydraulic conductivity of no more than 1 x 10-\7\ cm/s.\3\ 
See Sec.  257.71(a). Lined CCR surface impoundments (as defined in the 
CCR regulations) that impact groundwater above the specified GWPS were 
not required to close and could continue operations while corrective 
action was performed and the source of the groundwater contamination 
was addressed.
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    \3\ The liner terms ``compacted soil'' and ``clay-lined'' are 
used interchangeably in this preamble discussion.
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    On August 21, 2018, the U.S. Court of Appeals for the D.C. Circuit 
found in the USWAG decision that the rulemaking record did not support 
the conclusion that the 2015 CCR Rule would adequately address the 
adverse effects posed by clay-lined CCR surface impoundments. 
Therefore, the court vacated the provisions that treated clay-lined 
surface impoundments differently than unlined impoundments. USWAG, 901 
F.3d at 449. The result of the court's decision is that such units are 
now required to either retrofit or close. In response to this ruling, 
EPA received reports from industry groups and individual companies 
claiming that the performance of some surface impoundments that would 
now be required to retrofit or close is equivalent or even superior to 
the liners required by the 2015 CCR Rule.\4\ These impoundments rely on 
engineered liner components (e.g., manufactured geomembrane, 
mechanically compacted soil) that deviate from the requirements of the 
rule and/or on natural low-conductivity soil beneath the unit. EPA 
agrees that it is possible for individual impoundments that are not 
lined with a composite liner or an alternative composite liner (as 
those terms are defined in the CCR regulations) to still be protective 
of human health and the environment. This is possible if the effective 
hydraulic conductivity of the engineered liner and/or naturally 
occurring soil is so low that, even if leachate migrates from the unit, 
the volume of leachate that can be released to the underlying aquifer 
over the active life of the impoundment is so small that these releases 
will not result in adverse effects at any point in the future. 
Therefore, EPA proposed procedures in the March 2020 rule at Sec.  
257.71(d) to allow facilities to submit to EPA an alternate liner 
demonstration that would provide a sufficient record to support the 
continued operation of an unlined surface impoundment that can be shown 
to pose no reasonable probability of adverse effects to human health or 
the environment.
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    \4\ These reports are available in the docket to this 
rulemaking.
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    The current self-implementing regulations limit the ability of 
owners and operators to make a site-specific demonstration that the 
design of a particular CCR surface impoundment is equivalent to the 
composite liner system in Sec. Sec.  257.71(c); consequently, a 
regulatory revision would be necessary. However, the Agency's current 
record does not support conclusions on whether any individual 
impoundment has a low enough effective hydraulic conductivity to be 
protective, were the unit allowed to continue operations. This would 
require site-specific data, such as liner performance and surrounding 
hydrogeologic characterization information. The data relied upon in the 
2014 Risk Assessment were organized into distributions compiled at 
various geographic scales (e.g., local, regional, national). The 
resolution of these data were sufficient for identifying the potential 
for risk at a national scale. However, the same data cannot be used to 
draw conclusions about any individual impoundment. While reports 
submitted to EPA by industry since the finalization of the 2015 CCR 
Rule have provided valuable information about the characteristics of 
impoundments anticipated to perform equivalent to the liner system 
required by the 2015 CCR Rule, these reports generally did not include 
the type or specificity of data needed to support conclusions about 
individual impoundments.
    Therefore, owners and operators who believe an unlined surface 
impoundment meets the RCRA Sec.  4004(a) standard and should be allowed 
to continue operation as designed must provide EPA or a Participating 
State Director with the site-specific data and analysis necessary to 
demonstrate this fact. Based on the available groundwater monitoring 
and location restriction data posted on facilities' publicly accessible 
CCR internet sites, EPA believes that it is likely that only a small 
fraction of non-composite lined surface impoundments currently in 
operation will be able to apply successfully for this demonstration.

A. Factual Basis

    The factual record supporting the 2015 CCR Rule included a 
national-scale assessment of the risks associated with disposal of CCR 
in surface impoundments constructed with various liner types.\5\ As 
part of the 2014 Risk Assessment, EPA modeled peak groundwater 
concentrations that might occur in off-site wells up to a mile away for 
a duration of up to 10,000 years. This modeling effort identified 
potential risks from both unlined and clay-lined surface impoundments: 
The risk that

[[Page 72509]]

groundwater would be contaminated at levels exceeding GWPS and the risk 
arising from the exposure of human and environmental receptors to 
contaminated water. It is now known that a greater fraction of 
operating units are unlined than previously understood. This may shift 
the national-scale risks reported for all impoundments closer to the 
risks for just unlined units because a greater fraction of all 
impoundments would now be modeled as unlined, but it would not 
substantially alter the high-end risks already modeled for unlined 
impoundments. Thus, the change in liner designation would not impact 
the overall conclusions about risk drawn from the 2014 Risk Assessment. 
Based on this modeling, EPA estimated that releases from up to 36.2% of 
unlined impoundments and 9.1% of clay-lined surface impoundments could 
ultimately contaminate off-site wells.\6\ EPA is aware that monitoring 
data indicates that a higher percentage than this have exceeded GWPS. 
However, monitoring wells are located at the waste boundary, which 
invariably have higher concentrations than would be found up to a mile 
away from the unit, and includes additional contributions from 
background groundwater. In addition, a number of these impoundments are 
located near water bodies, which intercept some or all of the release 
before it can reach private wells on the opposite side. Therefore, EPA 
does not believe that the field data that has become available since 
finalization of the risk assessment conflicts with previous modeling 
results.
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    \5\ U.S. EPA. 2014. ``Human and Ecological Risk Assessment of 
Coal Combustion Residuals.'' Prepared by the Office of Solid Waste 
and Emergency Response. Washington, DC. December.
    \6\ U.S. EPA. 2014. ``Regulatory Impact Analysis: EPA's 2015 
RCRA Final Rule Regulating Coal Combustion Residual (CCR) Landfills 
and Surface Impoundments at Coal-Fired Electric Utility Power 
Plants.'' Prepared by the Office of Solid Waste and Emergency 
Response. Washington, DC. December.
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    As explained in the proposed rule, EPA considers it to be 
theoretically possible for some unlined and clay-lined units to achieve 
the same level of performance as the composite liners required by the 
2015 CCR Rule. In order for this to be the case, the effective 
hydraulic conductivity of the engineered liner and/or naturally 
occurring soil would need to be so low that, even if leachate migrates 
from the unit, the volume of leachate that can be transmitted to the 
underlying aquifer over time is small enough that it will not adversely 
affect groundwater quality. For a unit to achieve this, it would need 
to perform materially better than the clay-lined units evaluated in the 
2014 Risk Assessment. Those clay-lined surface impoundments were 
modeled with a fixed hydraulic conductivity of 1 x 10-\7\ 
cm/s and thickness of 3 feet, similar to the minimum design standard 
for clay-lined units outlined in the 2015 CCR Rule. For this fixed set 
of parameters, EPA identified risks slightly above the relevant risk 
criteria only for lithium, one of the most mobile CCR constituents.\7\ 
Based on these model results, an effective hydraulic conductivity of 
1x10\-8\ cm/s would be sufficient to reduce identified risks to below 
levels of concern on a national-scale. However, conditions present at 
individual facilities, such as the thickness of the low-conductivity 
soil or the presence of a geomembrane liner, might support somewhat 
higher soil conductivities on a case-by-case basis. Regardless, a 
conductivity of 1 x 10-\7\ cm/s for the lowermost soil 
component of the liner, whether in isolation or beneath a geomembrane 
component, remains the absolute floor for any unit to even be 
considered for an alternate liner demonstration.
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    \7\ Lithium had a non-cancer hazard quotient of 2.
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    EPA established the minimum liner requirements for CCR surface 
impoundments in the 2015 rule based on the original municipal solid 
waste landfill regulations at 40 CFR part 258. These requirements were 
based on the Agency's experience with various liner materials and 
reflect a uniform design that EPA expects to be reliably protective if 
manufactured and constructed properly. However, EPA acknowledged in the 
original 1991 rule (56 FR 51059, October 9, 1991) that alternative 
designs may be able to achieve the same performance. Thus, EPA also 
acknowledges that the fact that an individual unit does not meet the 
liner requirements of the 2015 CCR Rule does not in and of itself 
indicate that a unit will pose risk. Facilities that commented on the 
proposed rule reported units that were considered unlined based on the 
2015 CCR Rule definition for several reasons. Based on the available 
information from these comments and the Part 258 regulatory record, EPA 
identified three primary reasons that an alternately lined unit could 
still be protective.
    One type of impoundment that was classified as unlined, but which 
might still be demonstrated to be protective, is a unit where the soil 
was not mechanically compacted to the specified depth. It is well-
established in the literature that clay-rich soils can achieve 
hydraulic conductivities lower than 1 x 10-\8\ cm/s; 
however, this often requires some degree of compaction to break down 
any larger clumps of soil and minimize the volume of void spaces 
between soil particles that allow water to flow. Reports provided by 
some facilities purport that the necessary compaction of these soils 
had been accomplished onsite through natural processes. One example of 
the natural processes envisioned by commenters is glacial compaction, 
whereby stress from the weight and flow of the glacier compressed the 
naturally occurring soil. This process has been found to result in 
regions of soil with conductivities lower than 1 x 10-\8\ 
cm/s.\8\ Soils from around the perimeter of such units, which have 
historically been exposed to similar environmental conditions as the 
soil beneath the unit and so are expected to have similar 
characteristics, can be collected to confirm that necessary hydraulic 
conductivity is present and consistent across the site. Therefore, EPA 
believes the potential exists for facilities to successfully 
demonstrate that naturally compacted soil can be protective.
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    \8\ United States Department of the Interior. 1998. ``National 
Water-Quality Assessment of the Lake Erie-Lake St. Clair Basin, 
Michigan, Indiana, Ohio, Pennsylvania, and New York Environmental 
and Hydrogeologic Setting.'' Water-Resources; Investigations Report 
97-4256. Prepared by the United States Geological Survey. Columbus, 
OH.
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    Another type of unlined impoundment that may still be demonstrated 
to be protective is one where the layer of compacted soil was not thick 
enough to meet the current part 257 requirement. Based on EPA's 
experience with these liner materials, two feet of soil is the minimum 
thickness needed to reliably obtain adequate compaction and meet 
requirements for hydraulic conductivity. This thickness is considered 
necessary to minimize the number of cracks or imperfections through the 
entire liner thickness that could allow leachate migration. Based on 
EPA's experience, a two-foot minimum thickness is believed to be 
sufficient to reliably inhibit hydraulic short-circuiting of the entire 
layer. While it is possible to achieve low conductivities with a 
reduced thickness, there is a far greater risk of lateral and vertical 
imperfections that may arise during construction. Therefore, EPA 
believes that successful demonstration is possible here only if the 
facility can provide data showing the liner achieves an adequately low 
hydraulic conductivity in-situ.
    The final type of unlined impoundment that may still be 
demonstrated to be protective is one where the geomembrane liner used 
was not thick enough to meet the current part 257 requirement. The 
upper component of a composite-lined unit must consist of a minimum of 
a 30-mil

[[Page 72510]]

geomembrane liner, or 60-mil if the liner is constructed with high 
density polyethylene. Based on EPA's experience with these liner 
materials, these are the minimum thicknesses necessary to ensure 
adequate liner performance, including being able to withstand the 
stress of construction and to ensure that adequate seams can be made. 
Commenters argued that, due to improvements in welding technology and 
quality control procedures since these standards were first 
promulgated, concerns regarding welding thinner HDPE geomembranes have 
greatly diminished. If the facility is able to document the integrity 
of the liner design, then the performance of these liners will be 
primarily a function of construction quality. Commenters acknowledged 
that thinner liners are theoretically more susceptible to defects 
during installation, but also argued that no such trends have been 
identified in the literature. The 2014 Risk Assessment found that a 
well-constructed geomembrane liner can remain protective, even with a 
higher proportion of imperfections. Therefore, EPA believes the 
potential exists for facilities to successfully demonstrate that 
alternate geomembrane liners can be protective, provided that the soil 
directly beneath the geomembrane has sufficiently low conductivity.
    To support the conclusion that the long-term performance of an 
alternately lined CCR surface impoundment can meet the RCRA Sec.  4004 
protectiveness standard, EPA would need several categories of 
information. EPA proposed two categories of information that must be 
provided for the demonstration step, which the Agency is finalizing as 
part of this rulemaking. The first category is a characterization of 
the site-specific hydrogeology surrounding the surface impoundment. The 
purpose of these data is to define the variability of the soil around 
the surface impoundment to determine whether preferential flow pathways 
exist that effectively negate the low conductivity of the alternate 
liner. The second category of data is a characterization of the 
potential for infiltration through any engineered liner and/or 
naturally occurring soil that control the release and transport of 
leachate. These data will provide for a reasonable estimate of the rate 
at which contaminants may be released and transported to groundwater 
over time. Based on comments received, EPA is also finalizing a third 
category of information. This additional category is documentation of 
material properties and unit construction quality. The purpose of these 
data is to document that the impoundment can be expected to achieve the 
low conductivity specified in the unit designs. This category is 
included in the application step to confirm upfront that conditions 
simulated in a laboratory setting as part of the demonstration step are 
a reasonable reflection of field conditions.
    Thus, EPA concludes that there is potential for some existing 
unlined and clay-lined CCR surface impoundments to continue operating 
without presenting unacceptable risk. However, the Agency's current 
risk assessment does not support conclusions on whether any individual 
surface impoundment has a low enough effective hydraulic conductivity 
that operation of the unit will continue to be protective in the 
future. This would require the site-specific data discussed above, 
including, for example, data on the ability of the engineered liner 
and/or naturally occurring soil to limit the release and transport of 
leachate away from the unit. Therefore, EPA proposed procedures at 
Sec.  257.71(d) to allow facilities to submit such information to EPA 
to demonstrate that the engineered liner and/or naturally occurring 
soil will remain protective, and consequently the continued operation 
of an individual unlined surface impoundments will present no 
reasonable probability of adverse effects to human health or the 
environment.
    Specifically, EPA proposed a two-step process. In the first step, a 
facility would be required to submit an initial application to 
demonstrate that they meet certain minimum requirements before 
embarking on a comprehensive alternate liner demonstration. These 
minimum requirements are designed to ensure that it is likely a 
facility will ultimately be able to make the more extensive 
demonstration to support continued operation, and that the CCR surface 
impoundment can operate safely over the near term while the facility 
collects the data and conducts the analyses necessary to support the 
demonstration. In the second step, the facility would be required to 
submit the data and analyses necessary to support a determination that 
the CCR surface impoundment can sustain its current performance and 
operate safely for the remainder of its active life.
    Most industry groups and individual facilities voiced support for 
the option to make this type of demonstration, stating that the 
definition of a lined CCR surface impoundment in the 2015 CCR Rule is 
inflexible and would result in the unnecessary closure of some unlined 
CCR surface impoundments that, as designed, are as protective as lined 
CCR surface impoundments. Many environmental groups and private 
citizens were critical of the proposal and commented that it was 
unsupportable and would lead to greater risks to human health and the 
environment. Some of the same commenters noted that, while the types of 
information required may be useful to differentiate non-compliant and 
underperforming units, there were concerns that the amount of 
information required would be difficult or impossible to collect and 
review.
1. Existing Record
    Environmental groups stated the existing risk record does not 
support the conclusion that alternate liners can be protective, citing 
the potential risks identified for clay-lined units in the 2014 Risk 
Assessment. Some of these commenters further argued that the reports 
submitted by facilities to date are inadequate and similarly do not 
support the continued operation of the units documented therein. These 
commenters provided critiques of the individual units and concluded 
that the information provided in the associated reports is not 
sufficient to demonstrate whether on-site groundwater monitoring wells 
are adequate in number or construction to accurately reflect upgradient 
and downgradient conditions at the site. Further, commenters concluded 
that some facilities have inappropriately handled monitoring data to 
erroneously show that the CCR surface impoundment has not contaminated 
groundwater. Commenters also critiqued a report prepared by the 
Electric Power Research Institute (EPRI), which they claim shows that 
clay liners cannot be equivalent to composite liners in protecting 
health and the environment.
    As stated in the proposal and above, EPA agrees that neither the 
2014 Risk Assessment nor the industry reports support conclusions about 
any individual unlined surface impoundment. In order to draw 
conclusions about the protectiveness of any individual CCR surface 
impoundment, EPA needs site-specific information on the performance of 
the engineered liner and/or the naturally occurring soil. This is why 
EPA proposed a process for facilities to submit documentation that 
would support the continued operation of an unlined surface 
impoundment. At an absolute minimum, the performance of these CCR units 
would need to surpass that of the clay liners previously modeled, 
making them distinct from the far broader universe of clay-lined and 
unlined CCR surface impoundments considered in the USWAG decision.

[[Page 72511]]

    Although the reports submitted to EPA by individual facilities 
since finalization of the 2015 CCR Rule provide an indication on which 
impoundments are most likely to seek an ALD, EPA stated in the proposal 
that these reports did not include the type or specificity of data 
necessary to support conclusions about these individual surface 
impoundments. As a result, EPA did not rely on the conclusions of these 
reports to support any provisions of this final rule. As discussed in 
more detail below in Unit III.B, part of the purpose of the initial 
application step is to determine whether the types of deficiencies 
raised by commenters are present at a particular site, and if so, to 
ensure that these facilities do not progress to the longer ALD process.
    The report submitted by EPRI considered more broadly whether 
alternative liners can achieve GWPS near the CCR waste boundary. The 
modeling approach in many ways mirrored that used by EPA in the 2014 
Risk Assessment. Although EPRI initially made some assumptions that 
would tend to overestimate risk, such as ignoring the effects of 
constituent sorption onto the soil, these assumptions were later 
explored in select sensitivity analyses. Ultimately, EPRI found that 
even thick clay liners with a hydraulic conductivity of 1 x 
10-\7\ cm/s could result in exceedances of GWPS under high-
end conditions, while thinner clay liners with a conductivity at and 
above 1 x 10-\8\ cm/s did not. These results generally 
comport with the conclusions drawn from the 2014 Risk Assessment and 
suggest that there are plausible scenarios in which alternative liners 
can be protective. Critiques of the EPRI report by commenters focused 
heavily on the fact that the modeled clay liners did not perform 
equivalently to composite liners, meaning that the alternative liner 
could result in releases greater than a composite liner. However, after 
consideration of the comments received, the Agency believes this type 
of ``equivalence'' is not the appropriate standard to apply in an 
alternate liner demonstration. It would be difficult for an owner or 
operator to demonstrate that a clay liner of any thickness would 
prevent migration just as effectively as a composite liner, which 
includes a flexible membrane liner that, by design, is impermeable. 
Such a standard would unnecessarily limit the ability of owners and 
operators to utilize otherwise protective designs. Therefore, EPA 
believes the appropriate standard for an alternate liner demonstration 
is that there is no reasonable probability that releases throughout the 
active life of the CCR surface impoundment will result in adverse 
effects to human health or the environment. This is the standard relied 
upon in the 2015 CCR Rule to determine that composite-lined units were 
protective. This standard is achieved in an ALD by documenting that the 
peak groundwater concentration that may result from releases over the 
active life of the impoundment will not exceed GWPS at the waste 
boundary.
    Therefore EPA is making revisions at Sec.  257.71(d) to specify the 
owner or operator of a CCR surface impoundment constructed without a 
composite liner or alternative composite liner, as defined in Sec.  
257.70(b) or (c), may submit an Alternate Liner Demonstration to the 
Administrator or the Participating State Director to demonstrate that 
the design of the current liner system or the naturally occurring media 
will remain protective of human health and the environment.
2. Potential Risks to Surface Water
    Several environmental groups expressed concern that the focus on 
protection of groundwater would exclude protection of ecological 
receptors in nearby surface water. In particular, commenters 
highlighted the potential for some constituents to be toxic for aquatic 
wildlife at lower levels than for human ingestion of groundwater. These 
commenters also stated that the USWAG decision faulted EPA for not 
directly addressing potential risks to ecological receptors identified 
in the 2014 Risk Assessment. Another commenter pointed to the damage 
cases relied upon in the 2015 CCR Rule that identified additional risks 
to surface water.
    The 2014 Risk Assessment identified the potential for surface water 
risks from unlined units as a whole, but the existing risk record does 
not support similar concerns about units that would be able to obtain 
an ALD. Releases from the base of an impoundment will migrate down to 
groundwater prior to discharge into downgradient surface water. The 
risk assessment explicitly modeled this pathway and found that all 
surface water risks from clay-lined units fall below levels of concern 
by an order of magnitude or more. If the effective hydraulic 
conductivity of an alternate liner is sufficient to mitigate the 
groundwater risks previously identified in the risk assessment, then it 
will only further reduce downgradient releases to surface water through 
groundwater discharge. Thus, by demonstrating that an alternately lined 
impoundment can reliably perform better than the clay-lined units 
considered in the 2014 Risk Assessment, this confirms that these 
impoundments will pose no reasonable probability of adverse effects to 
surface water. Although damage cases considered in the 2015 CCR Rule 
identified some surface water impacts beyond those reported in the risk 
assessment, these were frequently associated with scenarios not 
explicitly modeled in the risk assessment, such as direct discharge of 
either CCR and/or associated wastewater to surface water or disposal of 
CCR in high-risk areas (e.g., within the groundwater table). These 
scenarios have already been addressed under RCRA through requirements 
for structural integrity and location restrictions, respectively. In 
addition, EPA is finalizing a requirement as part of this rule that 
facilities must remain in detection monitoring throughout both the 
application and demonstration steps. Ensuring that there is no SSI of 
Appendix III constituents throughout the demonstration will also ensure 
that Appendix IV constituents will not migrate beyond the waste 
boundary and pose risk to nearby ecological receptors while the owner 
or operator prepares the necessary documentation to demonstrate both 
that the facility complies with all relevant requirements of the 2015 
CCR Rule and that the long-term performance of the impoundment will be 
protective.
3. Continued Operation of CCR Surface Impoundments During Demonstration
    Industry groups agreed with EPA's basis for the proposed rule and 
stated that the D.C. Circuit had not precluded EPA from supplementing 
the existing risk record to support future decisions about individual 
unlined CCR surface impoundments. However, several environmental groups 
argued that the rule was in violation of the USWAG decision and 
contrary to RCRA. These commenters claimed that the D.C. Circuit 
decision required the closure of all unlined and clay-lined CCR surface 
impoundments and so any rule that would allow additional time for 
operation while the CCR surface impoundments complete a demonstration 
process would violate the decision. Others contended that allowing any 
additional time for operation would violate RCRA Sec.  4004(a) because 
it might provide deficient units additional time to contaminate 
groundwater before addressing the source.
    EPA disagrees with the suggestion that this rule is inconsistent 
with the USWAG decision. The D.C. Circuit held that the rulemaking 
record supporting

[[Page 72512]]

the 2015 CCR Rule did not support allowing clay-lined units to continue 
to operate indefinitely. 901 F.3d at 431-432. The court did not find 
that the statute per se prohibited such units, but that EPA had failed 
to provide enough evidence to demonstrate that the statutory standard 
had been met. Id. Consequently, EPA is not precluded from subsequently 
developing the evidence necessary to support the continued operation of 
some or all of these units. As discussed in greater detail in 
subsequent Units of this preamble, the record associated with the 
specific subset of impoundments that will be eligible under this rule 
is very different than the record associated with all units regulated 
under the 2015 CCR rule. For example, in the 2015 CCR rule the majority 
of units had been operating for years without groundwater monitoring or 
other regulatory requirements. The record for that rule documented that 
the majority of these units had likely been contaminating groundwater 
for years; EPA estimated that the contamination at these units had 
spread well beyond the waste boundary. And because there was no 
groundwater monitoring at these facilities, EPA was unable to 
distinguish between units that did pose a risk and those that did not. 
By contrast, only units that remain in detection monitoring throughout 
the application and demonstration process can be approved for an ALD. 
As discussed later in this preamble, EPA has also addressed the 
specific faults that the court found in EPA's prior record.
    EPA further disagrees with the suggestion that this rule fails to 
meet the standard in RCRA Sec.  4004(a). EPA purposefully divided the 
ALD process into two steps to weed out the facilities that fail to meet 
the RCRA Sec.  4004(a) standard. The initial application ensures that a 
facility is in compliance with applicable requirements in 40 CFR part 
257 subpart D, that the design of the monitoring network is sufficient 
to identify releases, that the CCR surface impoundment is in detection 
monitoring, and that the unit has the soil characteristics or 
engineering quality that would make it possible to meet the ultimate 
performance standard before a facility is granted any additional time 
to complete the more comprehensive alternate liner demonstration. The 
combination of these factors ensures that the only CCR surface 
impoundments allowed to progress to the demonstration step are those 
that EPA expects to remain protective during the year-long process to 
complete the demonstration.
    Because the initial application phase will be completed by April 
11, 2021 (the deadline for unlined surface impoundments to cease 
receipt of waste pursuant to Sec.  257.101(a)(1)), this process will 
grant additional time to operate only to CCR surface impoundments that 
continue to show that they can operate safely during the time it will 
take for the process to be completed. As discussed in more detail 
below, the initial application will be due no later than November 30, 
2020, and EPA will make a decision on whether the facility qualifies to 
submit a demonstration no later than April 11, 2021. Consequently, all 
facilities that submit an application must still be prepared to cease 
receipt of waste and to begin closure in the event that the application 
is ultimately rejected.
    Finally, CCR surface impoundments that are able to progress to the 
demonstration step will have shown that the design of the groundwater 
monitoring network is sufficient to identify releases from the unit and 
that there is currently no evidence that releases have occurred or are 
likely to occur while they are completing the demonstration.
    CCR surface impoundments are continuously full of water. The 
resulting hydraulic head on the liner can be considerably greater than 
found in landfills, which results in a greater and sustained potential 
for infiltration into the subsurface. The expectation is that releases 
from the unit to the subsurface would be limited primarily by the low 
hydraulic conductivity of the engineered liner and/or naturally 
occurring soil. Many of the surface impoundments at facilities that 
commented on the proposed rule have been in operation for over a decade 
and some for almost 70 years. If GWPS have not been exceeded throughout 
years of operation, this indicates that some combination of low 
conductivity soil, the thickness of the soil column above the aquifer, 
or a geomembrane liner component is effectively limiting or entirely 
preventing the release and transport of leachate. And for units such as 
these, with an adequate monitoring network, the fact that they have not 
triggered assessment monitoring means there is no evidence of any 
release to groundwater. In addition, these units will continue routine 
groundwater monitoring while preparing the demonstration to ensure that 
they continue to perform as anticipated over the year-long 
demonstration step. CCR units that trigger either assessment monitoring 
or corrective action at any point during the process would be rendered 
ineligible to proceed. Thus, any impoundment able to submit a 
successful ALD would not have had any discernable impact to groundwater 
quality.
    Moreover, it is highly unlikely that a unit with no prior 
indication of impacts to groundwater will contaminate groundwater above 
the GWPS within the relatively short timeframe permitted to complete 
the demonstration. Groundwater transport is a gradual process as the 
leachate migrates to and mixes with the groundwater. It is not 
realistic to expect a sudden exceedance of the GWPS after years of no 
detections from groundwater monitoring. Rather, one would expect to 
first see the more mobile constituents in Appendix III, such as total 
dissolved solids, before detecting any of the constituents of concern 
in Appendix IV. If a unit is leaking but has failed to identify the 
exceedance due to a deficiency with either the design or implementation 
of the groundwater monitoring program, that will be identified during 
the application review. Thus, there is no evidence that these units 
will present a risk of contaminating groundwater above GWPS or a risk 
to downgradient human or ecological receptors. Nonetheless, these units 
will continue routine groundwater monitoring while preparing the 
demonstration to ensure that the units continue to perform as 
anticipated.
4. Potential for Future Harm
    Some environmental groups contended that it does not matter whether 
an unlined unit can be shown to have no current groundwater 
contamination because the existing risk record shows that it can happen 
in the future. These commenters pointed specifically to the Agency's 
previous finding that a certain portion of unlined and clay-lined units 
are anticipated to eventually contaminate groundwater. Commenters 
further stated that allowing these units to continue operation is 
contrary to the USWAG decision because the risk record does not show 
whether any future release could be promptly detected and, once 
detected, promptly remedied before it can result in harm to human 
health or the environment. Commenters also pointed out that the risk is 
further compounded by the potential size of the plume from unlined 
units.
    EPA disagrees with the proposition that allowing CCR surface 
impoundments that meet the requirements for an ALD to continue 
operation is in violation of the USWAG decision. The D.C. Circuit found 
that it was contrary to RCRA Sec.  4004(a) to allow unlined and clay-
lined units to continue

[[Page 72513]]

operating because the rulemaking record failed to address a number of 
the risks associated with these units. For example, the record did not 
demonstrate that a leak from these units could be reliably contained 
and addressed before it resulted in harm to human health and the 
environment. 901 F.3d at 432. The D.C. Circuit specifically pointed to 
several factors that EPA had failed to address that might prolong the 
time required to address leaks, including the rate and extent of 
contaminant release, the well sampling schedule, and the time allowed 
to implement source control. Id at 42,432. However, the conditions 
established as part of this rule ensure that these issues will be 
sufficiently addressed for the subset of CCR surface impoundments able 
to obtain and operate under an ALD.
    First, units with an ALD that enter into assessment monitoring are 
required to conduct additional analyses to identify the presence and 
magnitude of any trends of increasing groundwater concentrations in 
downgradient wells. If these analyses show the potential exists for 
releases from the impoundment to result in an exceedance of GWPS within 
the timeframe needed to reliably close the unit, the facility must 
retrofit or close. This provision is intended to prevent adverse 
effects to groundwater and, if necessary, to expedite remedial efforts. 
Use of trend analysis is appropriate to monitor for evidence of 
increasing groundwater concentrations because the release and transport 
of inorganic elements through the subsurface is a gradual and steady 
process. The presence of low conductivity soil beneath a unit would 
only further limit the speed at which contamination can spread. For 
example, based on the range of anticipated hydraulic gradients and 
other relevant soil properties, groundwater moving through soil with a 
hydraulic conductivity of 1 x 10-\7\ cm/s would be expected 
to progress less than a foot a year.\9\ In this context, there is 
little concern that the time between semi-annual monitoring events 
would substantially delay identification of potential 
contamination.\10\
---------------------------------------------------------------------------

    \9\ The maximum hydraulic gradient considered in the 2014 Risk 
Assessment was 1.0 ft/ft.
    \10\ Additionally, it is notable that the semi-annual timing 
between sampling events is designed to ensure a degree of 
statistical independence in assembled monitoring data. Too-frequent 
sampling at a given background well can result in highly 
autocorrelated, non-independent data that can reduce the accuracy of 
statistical tests.
---------------------------------------------------------------------------

    Even if corrective action were triggered before closure could be 
completed, this in no way prevents the concurrent implementation of 
corrective measures beyond the waste boundary to contain the plume and 
prevent downgradient exposures. EPA has previously documented how pump 
and treat can be systematically applied to control plume migration, 
even when the contaminant source has not yet been addressed.\11\ 
Furthermore, facilities that are able to submit a successful 
demonstration will be among the most well-characterized units in the 
country, which would further limit the timeframe needed to contain the 
plume and the potential for unforeseen setbacks that could result in an 
inadequate understanding of local hydrogeology.
---------------------------------------------------------------------------

    \11\ U.S. EPA. 2008. ``A Systematic Approach for Evaluation of 
Capture Zones at Pump and Treat Systems.'' EPA 600/R-08/003. 
Prepared by the Office of Research and Development. Cincinnati, OH. 
January.
---------------------------------------------------------------------------

    Ultimately, EPA believes that a judgement on whether a plume can be 
addressed promptly should be based on the potential for immediate and 
future harm. This is consistent with the established criteria in Sec.  
257.97(d) that require the development of a reasonable schedule to 
implement remedial actions to be based on a number of factors, such as 
the immediacy of risk to nearby receptors and the risk of contaminant 
spread to other environmental media. Altogether, these factors will 
help ensure that any contamination identified at the waste boundary can 
be addressed before it results in risk to downgradient receptors, 
regardless of the original extent of the release.
    EPA is also confident that contamination at these sites can be 
successfully remediated. The inorganic constituents on Appendix IV are 
not novel. Issues of impracticability at corrective action sites are 
often associated with the ability to access contaminants in the 
subsurface. The primary causes have been the hydrophobic behavior of 
organic compounds, which is not relevant in this context, and the 
presence of complex site hydrogeology.\12\ The CCR location 
restrictions at Sec.  257.64 prohibit disposal in karst and other 
unstable areas that might confound remedial efforts. Other highly 
complex geology, such as fractured bedrock, is notoriously resistant to 
modeling and unlikely to allow for a successful demonstration. Although 
corrective action at the remaining sites may be technically complex, it 
remains feasible. Therefore, there is little concern that corrective 
action, if required, would not eventually achieve established cleanup 
goals. For all these reasons, the Agency is not making any amendments 
to the proposal as a result of these comments.
---------------------------------------------------------------------------

    \12\ U.S. EPA. 2012. ``Summary of Technical Impracticability 
Waivers at National Priorities List Sites.'' OSWER Directive 9230.2-
24. Prepared by the Office of Solid Waste and Emergency Response. 
Washington, DC. August.
---------------------------------------------------------------------------

B. Application

    In the March 2020 proposed rule, EPA proposed to establish a two-
step process: Requiring an initial application followed by the 
submission of the alternate liner demonstration. The application step 
is designed to ensure that a surface impoundment meets minimum 
requirements before embarking on a comprehensive alternate liner 
demonstration.
    The Agency proposed that in order to apply for an ALD, an owner 
operator must first submit a letter to EPA declaring their intention to 
submit a demonstration under the provision. EPA also proposed that 
along with the letter, a facility must provide documentation showing 
(1) that a facility is in compliance with all applicable requirements 
in 40 CFR part 257 subpart D, including all location restrictions, and 
(2) that there has not been an exceedance of any Appendix IV 
constituents. EPA further proposed that, as part of this demonstration, 
a facility must submit documentation to show that the existing network 
of monitoring wells is sufficient to identify any releases based on 
direction of flow, well location, screening depth, and other relevant 
factors. EPA proposed that this could include well construction logs 
and a sufficient number of diagrams to depict depth to groundwater, the 
potentiometric surface, and the anticipated directions of groundwater 
flow across the site. Finally, EPA proposed to require the facility to 
show there is no indication from groundwater monitoring data that the 
unit has or will adversely affect groundwater, in part by providing 
documentation of the most recent statistical tests conducted and the 
rationale for the methods used in these comparisons. Upon submission of 
the application, a copy of the written demonstration and all associated 
documentation must be simultaneously posted to the facility's publicly 
accessible CCR internet site.
    No commenter raised concern about EPA's proposal to require the 
submission of a letter or the specific requirements applicable to the 
letter or the two categories of accompanying information required to be 
submitted. However, some commenters broadly requested that EPA provide 
greater clarity on the types of information that must be submitted for 
the application to be considered complete, while other commenters asked 
for greater clarity on

[[Page 72514]]

the specific elements necessary to satisfy the requirements of the 
rule.
    EPA is finalizing much of Sec.  257.71(d)(1) as proposed--retaining 
the requirement to submit a letter and accompanying information to 
demonstrate that certain minimum criteria have been met. The final rule 
also retains the requirements to submit documentation showing that a 
facility is in compliance with all applicable requirements in 40 CFR 
part 257 subpart D, including all location restrictions. However, the 
final rule includes a modified provision requiring facilities to 
demonstrate that there has not been a statistically significant 
increase over background levels of any Appendix III constituents 
throughout the application and demonstration process. EPA has also made 
several modifications in response to comments requesting greater 
clarity. Other changes were made to conform the procedures in this 
rulemaking with the procedures recently adopted in Sec.  257.103. These 
topics are discussed in further detail in the next Units of this 
preamble.
1. Application Letter
    EPA proposed that the owner or operator must first submit a letter 
to EPA declaring their intention to submit an alternate liner 
demonstration. EPA received no comments that raised questions or 
concerns about the substantive information to be included in the 
letter. Consequently, the final rule adopts these requirements without 
substantial revision. The final rule requires the owner or operator of 
the CCR surface impoundment to submit a letter to EPA or the 
Participating State Director. This letter will announce the owner or 
operator's intention to submit an alternate liner demonstration. The 
application must include the location of the facility and identify the 
specific CCR surface impoundment for which the demonstration will be 
made. The application letter must also include the information in Sec.  
257.71(d)(1)(i)(A) through (D), as specified in the regulatory text, 
and further described below.
2. Compliance With the CCR Regulations and Required Documentation
    Along with the letter, EPA proposed at Sec.  257.71(d)(1)(i)(A) 
that the owner or operator must submit information to EPA documenting 
that the facility is in compliance with the applicable requirements in 
40 CFR part 257, subpart D.
    EPA continues to believe that requiring facilities to document 
compliance with the subpart D of part 257 requirements is an important 
part of the demonstration. Compliance with the rule provides critical 
support for the determination that these units will not present the 
types of risks identified in the damage cases considered in the 2015 
CCR Rule. For example, some of the damage cases resulted from disposal 
in high-risk areas (e.g., within the groundwater table). These issues 
will be addressed through documenting that the surface impoundments 
meet the requirements of the 2015 CCR Rule (e.g., location 
restrictions). Similarly, documenting compliance with the groundwater 
monitoring requirements shows that the design of the groundwater 
monitoring network is sufficient to identify groundwater contamination 
in the uppermost aquifer. This, together with the fact that the unit 
remains in detection monitoring, demonstrates that there is currently 
no evidence the risks modeled in the 2014 Risk Assessment are present 
or will result from continued operation of the impoundment in the near 
term.
    Overall, compliance with part 257, subpart D generally provides 
some guarantee that the risks at the facility are properly managed and 
adequately mitigated. Consequently, this determination provides 
critical support for a decision to allow continued operation of the 
alternately lined surface impoundment. This means that EPA must be able 
to affirmatively conclude that the facility meets this criterion prior 
to authorizing any continued operation of the surface impoundment. It 
also means that EPA cannot grant facilities additional time to cure any 
noncompliance. However, EPA's determination will be prospective only; 
accordingly, for purposes of the ALD process, EPA is only interested in 
the state of a facility's current compliance rather than any instances 
of historic non-compliance.
    In response to commenters who requested that EPA provide greater 
specificity about what constitutes a complete submission, EPA has 
amended the regulatory text to identify specific documents that the 
owner or operator of a CCR unit must provide to demonstrate its current 
compliance with the requirements of part 257, subpart D. Most of these 
documents are the same documents that EPA is requiring facilities to 
provide under the recent amendments to Sec.  257.103. Further, these 
documents should already exist either because they would have had to be 
compiled when the unit was first constructed, or they were required to 
be developed under the existing regulations.
    Consistent with the recent amendments to Sec.  257.103 (85 FR 
53516, August 28, 2020), EPA has decided that a certification of 
compliance and the requirement to remain in compliance with the 
regulations are also necessary in this final rule. The compliance 
certification is represented at Sec.  257.71(d)(1)(i)(A) to require a 
certification signed by the owner or operator of the CCR unit saying it 
is in full compliance with part 257, subpart D, except for the 
requirement to document that the unit is constructed with either a 
composite liner or alternative composite liner under Sec.  
257.71(a)(1). This approach will prevent non-compliant unlined surface 
impoundments from operating for an extended period of time into the 
future. Requiring that only compliant surface impoundments can be 
approved for an ALD provides additional support for EPA's conclusion 
that this final rule meets the statutory standard.
3. Groundwater Monitoring Network Documentation
    EPA proposed at Sec.  257.71(d)(1)(i)(B) that the facility must 
show in the initial application that the existing network of monitoring 
wells is sufficient to identify any releases based on direction of 
flow, well location, screening depth and other relevant factors, 
including well construction logs and a sufficient number of diagrams to 
depict depth to groundwater, the potentiometric surface, and the 
anticipated direction(s) of groundwater flow across the site (multiple 
diagrams may be necessary if the direction of flow is affected by 
seasonal, tidal or other influences). EPA also proposed that these 
diagrams should include all the water table measurements reported from 
a standard datum, a map scale, and a legend of any important map 
symbols. EPA proposed that facilities that have improperly placed 
groundwater monitoring wells would not be eligible to apply or submit 
an alternate liner demonstration.
    Many commenters requested greater specificity on the types of 
information required for this part of the application. Some questioned 
whether facilities will be required to gather additional groundwater 
and other site-specific data in support of the application, or whether 
facilities only needed to submit previously collected groundwater 
monitoring data and analyses conducted for their sites. One commenter 
asked whether the application required specific information, such as 
representative geologic cross sections, groundwater contour maps of the 
facility, or other hydrogeologic data. Another requested inclusion of a

[[Page 72515]]

requirement that facilities include the depth of water ponded in the 
impoundment to ensure that wells intended to reflect background 
conditions are not impacted by groundwater mounding. Some commenters 
pointed out that some of the elements required in the application are 
standard components of the annual groundwater monitoring and corrective 
action reports already required by Sec.  257.90(e). Examples include 
groundwater flow maps and statistical test results. These commenters 
requested that the monitoring reports and other existing documentation 
be allowed to substitute for some or all of the application through 
citation, weblink, or other reference. Although some commenters 
acknowledged that the information requested would facilitate review of 
the application, others protested the additional burden of repackaging 
information.
    The intent of this provision is to allow for a comprehensive review 
of the existing well network to determine whether it is sufficient to 
identify releases from the unit that have occurred or might occur in 
the future. EPA did not intend to require the collection of any further 
groundwater data or other site-specific data for the purposes of the 
application. Facilities have already designed and implemented their 
site groundwater monitoring programs, and EPA expects the facility 
would normally have generated the information specified in Sec.  
257.71(d)(1)(i)(B)(1) of this final rule, either as part of developing 
or implementing the groundwater monitoring program. However, facilities 
are encouraged to provide additional detailed interpretation of the 
data and analyses for consideration during the review.
    EPA proposed that the application include documentation of relevant 
factors considered by the owner or operator when determining the 
appropriate number and placement of monitoring wells. As highlighted by 
some commenters, this should include characterization of the local 
hydrogeology, including the factors detailed in Sec.  257.91(b), and 
the potential for groundwater mounding beneath the unit to affect 
characterization of background. However, the appropriate types of data 
and level of detail will depend largely on the complexity of the site. 
As a consequence, EPA is not requiring every facility to incorporate 
discussion of the depth of impounded water as part of the justification 
for well placement. Any potential for groundwater mounding should have 
been accounted for when the wells were first installed and so should be 
reflected in the documentation already required. If mounding is found 
to be present, then this information must be reflected in any maps of 
groundwater elevation and flow direction. However, it is considered 
highly unlikely that a facility with appropriately located wells and 
releases substantial enough to result in groundwater mounding would 
remain in detection monitoring and be eligible for an ALD.
    Because this record already exists, the facility would only be 
required to provide all the data and analyses that were relied upon to 
comply with the relevant standards of the CCR regulations. However, 
documenting that the existing well network meets the standard in this 
rule will require a level of detail and discussion beyond what is 
required in a routine groundwater monitoring report. And, although such 
reports contain a subset of the required information, it is likely to 
be divided up among a number of different documents. This will 
complicate and extend the review process because the key data and 
figures will not be presented alongside the relevant discussion to 
provide proper context. Thus, applications that incorporate the 
required information solely through reference will be considered 
incomplete.
    Because this information is already available, preparation of the 
application should not require much additional work beyond compiling 
information in a concise and coherent fashion. EPA discourages 
facilities from sending hundreds or thousands of pages of laboratory 
printouts and other raw data; instead, EPA expects the data to be 
presented in a tabular or other format that has gone through a quality 
control process to present the data in a concise format. The types of 
data and analyses considered by facilities beyond what is required to 
be presented as part of monitoring reports may appropriately vary on a 
case-by-case basis.
    Therefore, EPA is finalizing the provisions at Sec.  
257.71(d)(1)(i)(B)(1) with amendments to specify the documents that the 
facility must provide to demonstrate how it has complied with each 
requirement in Sec.  257.91. The regulatory text can provide an 
effective checklist for facilities to follow. In order to review a 
facility's current compliance with the requirements governing 
groundwater monitoring systems, the Agency will need the following 
updated list of information: (1) Map(s) of groundwater monitoring well 
locations (these maps should identify the CCR units as well) that 
depict the elevation of the potentiometric surface and the direction(s) 
of groundwater flow across the site; (2) well construction diagrams and 
drilling logs for all groundwater monitoring wells; (3) maps that 
characterize the direction of groundwater flow accounting for temporal 
variations; and (4) any other data and analysis the facility relied 
upon when determining the number and placement of wells around the unit 
compiled in a concise and readable format.
4. No Adverse Effects on Groundwater Documentation
    EPA proposed at Sec.  257.71(d)(1)(i)(C) that facilities must 
demonstrate that there is no indication from groundwater monitoring 
data that the unit has or will adversely affect groundwater (i.e., no 
statistically significant levels (SSL) of Appendix IV constituents 
above relevant GWPS), including documentation of the most recent 
statistical tests conducted and the rationale for the methods used in 
these comparisons. Facilities that have conducted improper statistical 
analysis of groundwater monitoring results would not be eligible to 
apply or submit a demonstration.
    The Agency received comments about the proposed language that a 
facility must demonstrate ``there is no indication from the groundwater 
monitoring data that the unit has or will adversely affect groundwater 
. . .'' Commenters expressed concern that this standard was more 
stringent than required by the subsequent demonstration step and may 
necessitate collection of an unspecified amount of additional data, 
such as sampling for Appendix IV constituents at units that had not 
progressed beyond detection monitoring, which they worried would not be 
possible to obtain prior to the application deadline.
    As discussed previously, EPA did not intend for facilities to 
conduct additional rounds of sampling for the application beyond that 
required for ongoing compliance with the CCR regulations. The 
referenced preamble language was intended to convey that the monitoring 
data collected to date must show that there is currently no evidence 
that the unit has contaminated groundwater, as well as no evidence that 
it might do so in the future. The language in question was based on the 
assumption that units presently in assessment monitoring could submit 
an application. However, EPA has reconsidered that position in light of 
comments received. The final rule instead requires that all units must 
stay in detection monitoring to remain eligible for an ALD. The fact 
that a unit remains in detection monitoring

[[Page 72516]]

provides better evidence to demonstrate that the standard in the 
proposed rule has been met (i.e., that the unit is not currently 
causing adverse effects), and that such effects are not expected to 
occur in the near term. EPA acknowledges, as demonstrated for 
composite-lined units in the 2014 Risk Assessment, that releases can 
occur from even the most well-designed units and that these 
impoundments can remain protective. However, greater assurance that the 
impoundment can continue to operate safely throughout the approval 
process is necessary at this stage, prior to the demonstration that the 
ultimate performance standard in this rule has been met.
    To reflect these changes, EPA is adopting a provision at Sec.  
257.71(d)(1)(i)(B)(2) to specify that facilities must demonstrate that 
the unit remains in detection monitoring as a precondition for 
submitting an application. Consistent with the proposal, as part of 
demonstrating that the facility remains in detection monitoring, the 
owner operator must document the most recent statistical tests 
conducted and the rationale for the methods used in these comparisons.
    Many industry and some state commenters requested greater 
specificity on the types of information required for this part of the 
application. One commenter requested clarification on the relationship 
between these requirements and those found in Sec.  257.93 and Sec.  
257.94. Another commenter asked whether a qualified professional 
engineer's certifications that the groundwater monitoring program meets 
the requirements of the 2015 CCR Rule would provide sufficient 
documentation.
    The intent of this provision is to allow for a comprehensive review 
of the facility's determination that a unit has not adversely affected 
groundwater. Certification from a qualified professional engineer alone 
would not provide the necessary documentation. EPA proposed that 
facilities include documentation of the most recent statistical test 
and rationale for the methods selected. Whether the results of the 
statistical tests are valid depends on all the data and analyses that 
underpin it. The documentation must demonstrate that the 
characterization of groundwater quality is sufficient; the management 
of collected monitoring data has been properly considered and addressed 
non-detect data, trends, and other relevant factors that may affect 
data quality; and that the statistical tests applied are appropriate. 
The specific standards that the application must address are detailed 
in Sec.  257.93 through Sec.  257.94.
    Therefore, EPA is finalizing Sec.  257.71(d)(1)(i)(B)(2) with 
amendments to specify that the facility must document how it has 
complied with each requirement in Sec. Sec.  257.93 through 257.94. The 
regulatory text in these sections can provide an effective checklist 
for facilities to follow. To support that demonstration, the final rule 
requires facilities to provide the following: (1) Documentation of the 
most recent statistical test; and (2) the rationale for the methods 
used in these comparisons. As part of this rationale, the facility must 
provide all data and analyses relied upon to comply with each 
requirement.
5. Location Restrictions
    EPA proposed at Sec.  257.71(d)(1)(i)(D) that a unit must be in 
compliance with all relevant location restrictions at Sec. Sec.  257.60 
through 257.64 in order to be eligible for an ALD.
    Many industry commenters requested greater specificity on the types 
of information required for this part of the application. Specifically, 
commenters inquired whether facilities were expected to submit the 
entire package of location restriction demonstrations, or if they can 
simply certify that the CCR surface impoundment meets all location 
restrictions. The documents that demonstrate a unit meets a location 
restriction should already exist because they are required under the 
existing regulations. Location restrictions were established to ensure 
that units are constructed in suitable geographic areas. Prohibited 
locations reflect areas where local conditions have the potential to 
compromise the integrity of the unit or where, if contamination were to 
occur, the damages could be particularly severe or difficult to 
remediate. EPA still believes this is critical to the record supporting 
continued operation of the unit. Consequently, facilities must submit 
the entire package of location restriction demonstrations.
    Therefore, EPA maintains that documentation that the facility is in 
compliance with all location restrictions must be submitted to EPA or 
the Participating State Director as a requirement of the initial 
application and is finalizing Sec.  257.71(d)(1)(i)(B)(3).
6. Structural Stability and Safety Factor Assessment Submission
    In order to align with the recent amendments to Sec.  257.103 (85 
FR 53516, August 28, 2020)(``Part A final rule''), this final rule 
specifies that a facility must submit the facility's most recent 
structural stability assessment required at Sec.  257.73(d) and safety 
factor assessment required at Sec.  257.73(e) at Sec.  
257.71(d)(1)(i)(B)(4) and (5). EPA's intention to review these items 
was discussed in the proposed rule as part of the discussion when 
discussing that a unit must be in full compliance with the 2015 CCR 
Rule. EPA received no comments raising concern about inclusion of this 
requirement. The inclusion of this requirement also responds to 
requests that EPA provide greater specificity on the documents that 
must be submitted as part of the application.
    The Agency recognizes that the requirement to conduct periodic 
structural stability assessments and safety factor assessments is not 
applicable to all CCR surface impoundments. As specified in Sec.  
257.73(b), only those impoundments with a height of five feet or more 
and a storage volume of 20 acre-feet or more, or those impoundments 
with a height of 20 feet or more are subject to these assessment 
requirements. An owner or operator submitting an ALD application for a 
unit not meeting these thresholds must include an affirmative statement 
in the certification signed by the owner or operator under Sec.  
257.71(d)(1)(i)(A) indicating that the impoundment is not subject to 
the structural stability and safety factor assessment requirements 
under Sec.  257.73(d) and (e). Similarly, EPA is aware that not all 
impoundment dikes were constructed with soils that are susceptible to 
liquefaction, and thus are not subject periodic safety factor 
assessments showing that the calculated liquefaction factor of safety 
equals or exceeds 1.20. See Sec.  257.73(e)(1)(iv). For impoundments 
not constructed with soils subject to liquefaction and subject to the 
safety factor assessment requirements, the owner or operator must 
include an affirmative statement in the certification required under 
Sec.  257.71(d)(1)(i)(A) stating that the unit is not subject to the 
liquefaction factor of safety because it has been determined that the 
dike(s) was not constructed with soils subject to liquefaction.
7. Documentation of Source Material and Construction Quality
    EPA noted in the proposal that geomembrane liners are not as 
sensitive to the chemical composition of coal ash leachate as soil-
based liners and so performance may depend more on the frequency and 
magnitude of imperfections that arise during installation. In these 
instances, laboratory infiltration tests on pristine samples are 
unlikely to provide representative data on field performance. EPA 
discussed

[[Page 72517]]

construction quality reports as a type of documentation that could 
support characterization of geomembrane liner performance in the field. 
However, EPA did not require the submission of any particular documents 
as part of the application.
    Multiple commenters indicated that historical data on the 
construction of impoundments is important to understand whether a unit 
can perform as intended. Commenters identified several specific factors 
they believed should be part of the submission, such as the initial 
saturation, compactive effort, plasticity index, subgrade water 
content, and clay content of the liner. One commenter also warned that 
specifications on a manufacturer's product sheet alone may not provide 
adequate assurance of good performance in the field.
    EPA agrees that considerations of construction quality are equally 
relevant to all types of liners. Indeed, the ability of any liner to 
achieve performance objectives is predicated on the quality of both the 
source materials and the construction of the surface impoundment. 
Therefore, EPA concludes that information on both must be incorporated 
in the application to provide evidence that the unit has the soil 
characteristics or engineering quality that would make it possible for 
the unit to meet the ultimate performance standard is expected to 
remain protective in the near term while the comprehensive 
demonstration is completed. The relevant types of information will 
depend on the design of the surface impoundment. Consequently, EPA is 
not specifying particular documents or data that must be submitted for 
every impoundment.
    Source quality testing ensures that the materials used to construct 
the liner conform with project specifications and are able to meet the 
necessary standards. However, EPA has found negligible correlation 
between field hydraulic conductivity and many of the common soil 
characterization parameters identified by the commenter, such as 
plasticity index and clay content.\13\ As a result, EPA previously 
concluded that it is difficult to determine whether a particular soil 
is suitable for use as a liner based solely on individual index 
properties and without relevant confirmatory testing. For engineered 
soils, this will involve establishing the relationship between water 
content, density, and hydraulic conductivity in a laboratory setting 
before construction begins to ensure the liner will be installed under 
optimum conditions. For naturally-occurring soils, this will involve 
testing that the pre-existing soil structure achieves a sufficiently 
and consistently low hydraulic conductivity. For geomembrane liners, 
this involves confirming that the material can withstand the stresses 
it will be exposed to and that the seams of the liner can be reliably 
welded to meet performance requirements. Altogether, this information 
provides evidence that these materials can meet relevant performance 
objectives during operation.
---------------------------------------------------------------------------

    \13\ U.S. EPA. 2002. ``Assessment and Recommendations for 
Improving the Performance of Waste Containment Systems.'' EPA/600/R-
02/099. Prepared by the Office of Research and Development. 
December.
---------------------------------------------------------------------------

    Construction quality testing ensures that surface impoundment 
construction has been performed in accordance with all relevant 
technical specifications before any waste is accepted. EPA stated in 
the proposal that collection of in-situ data from an operating surface 
impoundment will generally be impracticable because of the potential to 
disrupt the integrity of the liner, and some facilities agreed in their 
comments. However, laboratory testing cannot account for operational 
problems during construction that result in substandard conditions, 
such as desiccation, cracking, poor bonding, and inconsistent 
compaction of the liner. There are no standardized laboratory tests 
designed to simulate a liner that has been poorly designed or 
constructed. Therefore, without contemporaneous documentation that the 
surface impoundment liner was well constructed, it will be too 
difficult to confirm that any data subsequently collected for the 
demonstration reliably represents actual liner conditions. In 
particular, for soil liners that do not meet the thickness requirement 
of the rule, field testing is likely the only reliable way to ensure 
that construction has achieved a sufficiently low and consistent 
hydraulic conductivity. Considerable guidance exists on factors that 
must be addressed to ensure the quality of a liner, such as: the proper 
thickness, compaction, moisture content, and density of compacted soil; 
the in-situ hydraulic conductivity of compacted soil; protection of 
soil from desiccation and freezing; placement of the geomembrane liner 
without excessive waves, with a goal of ensuring intimate contact 
between the liner and the underlying soil; and protection of 
geomembranes from puncture by adjacent materials or equipment. 
Altogether, this information provides evidence that the liner is well 
constructed and can be reasonably simulated in a laboratory setting.
    EPA is finalizing a new requirement at Sec.  257.71(d)(1)(i)(C) 
that facilities are required to provide documentation of the design 
specifications for any engineered liner components (e.g., manufactured 
geomembrane, mechanically compacted soil), as well as all data and 
analyses the facility relied on when determining that the materials are 
suitable for use and that the construction of the liner is of good 
quality and in line with proven and accepted engineering practices.
8. Additional Release Pathways
    In the proposal, EPA stated that in some instances direct 
infiltration to groundwater may not be the sole mechanism by which 
unpermitted release of leachate from a surface impoundment occurs. It 
is possible that additional, site-specific release pathways may exist 
for some impoundments. For example, there may be lateral transport from 
the surface impoundment directly into the water body driven in part by 
the hydrostatic head within the surface impoundment. EPA listed 
proximity to a water body, construction above grade, lack of a 
geomembrane liner, and the presence of low conductivity soil beneath 
the unit as factors that could contribute to such releases. EPA stated 
that, if such conditions are present at a site, then the demonstration 
would need to address whether such releases may occur and the potential 
adverse effects on health or the environment associated with these 
pathways. The same types of data collected to evaluate releases to 
groundwater should also support evaluation of such pathways.
    EPA received no adverse comments on this topic. One commenter 
affirmed that such pathways are possible and are a concern. No 
commenters identified other relevant subsurface release pathways beyond 
the one contemplated in the proposal.
    Upon further consideration, EPA now believes that this type of 
release is already adequately addressed by the requirements of Sec.  
257.96(a). Because this issue involves compliance with an aspect of the 
2015 CCR Rule, EPA believes it is most appropriately addressed as part 
of the application step. As clarified in the Phase One Rule, this 
provision requires a facility to commence corrective action 
``immediately upon detection of a release from a CCR unit'' for any 
non-groundwater releases. 83 FR 11584 (March 15, 2018). Thus, the 
existence of subsurface releases directly to surface water would 
trigger immediate corrective action. Further, unlike groundwater, there 
is no standardized

[[Page 72518]]

method to monitor the progression or effects of this type of release to 
confirm that the unit remains protective. Therefore, if the design of a 
surface impoundment cannot be shown to reliably prevent such releases, 
it would be ineligible for an ALD.
    Therefore, EPA is finalizing a requirement at Sec.  
257.71(d)(1)(i)(D) that facilities with surface impoundments located on 
properties adjacent to a water body must demonstrate that there is no 
reasonable probability that a complete and direct transport pathway 
(i.e., not mediated by groundwater) could exist between the impoundment 
and any nearby water body. If the potential for such releases is 
identified, then the unit would not be eligible to submit a 
demonstration. If ongoing releases are identified, the owner or 
operator of the CCR unit must address these releases in accordance with 
Sec.  257.96(a).

C. Alternate Liner Demonstration

    EPA proposed that the ALD must present evidence to demonstrate, 
with a reasonable degree of certainty, that based on the construction 
of the unit and surrounding site conditions, operation of the surface 
impoundment will not result in groundwater concentrations above 
relevant GWPS at the waste boundary.
    EPA proposed at Sec.  257.71(d)(1)(ii) that the liner 
demonstrations must be certified by a professional engineer. Some 
commenters requested that the qualifications necessary to certify the 
ALD be broadened beyond professional engineers to include geologists 
and hydrogeologists. The commenter noted that licensed professional 
geologists or hydrogeologists are trained and experienced in 
investigation and analysis of groundwater and subsurface contaminant 
flow and chemistry. EPA previously considered this exact request and 
rationale as part of the 2015 CCR Rule. The Agency concluded there 
that, while some environmental professionals (e.g., hydrologists, 
geologists) may be qualified to make certain certifications, EPA was 
not convinced that either hydrologists or geologists licensed by a 
state are held to the same standards as a professional engineer. 80 FR 
21337 (April 17, 2015). One commenter requested that EPA use the term 
``qualified professional engineer'' rather than ``professional 
engineer,'' as this is the term that was used in the 2015 CCR Rule. EPA 
agrees with this suggestion and will be finalizing the rule requiring 
that certification must be provided by a ``qualified professional 
engineer''.
    The qualified professional engineer must certify that the 
demonstration package presents evidence to demonstrate that there is no 
reasonable probability that peak groundwater concentrations that may 
result from releases throughout the active life of the surface 
impoundment will exceed GWPS at the waste boundary based on the 
construction of the unit and surrounding site conditions.
    EPA proposed two lines of evidence for which site-specific data 
must be collected and incorporated into the demonstration. These are 
the characterization of site hydrogeology and the potential for 
infiltration. EPA identified these lines of evidence because the 
hydraulic conductivity of the engineered liner and/or naturally 
occurring soil is expected to be the primary mechanism that will limit 
release and transport of contaminants from the unit. These data will be 
used to model the potential for the release of contaminants and their 
transport through the environment. For each line of evidence, as well 
as any other data and assumptions incorporated into the determination, 
EPA proposed that the facility must include documentation on how the 
data were collected and why these data and assumptions are believed to 
adequately reflect potential contaminant transport at and around that 
specific surface impoundment.
1. Line of Evidence #1--Characterization of Site Hydrogeology
    The first line of evidence that EPA proposed at Sec.  
257.71(d)(1)(ii)(A) requires characterization of the variability of the 
site-specific soil and hydrogeology that surrounds the CCR surface 
impoundment. Some surface impoundments are located on soils that are 
expected to have extremely low hydraulic conductivity. However, there 
are concerns that heterogeneity within these soils may result in 
preferential flow pathways that effectively negate the low conductivity 
of the remaining soil. For example, many electric utilities are located 
in close proximity to bodies of water. The flow path of these water 
bodies is likely to have shifted over geologic time, which could result 
in complex depositional environments with interconnected lenses of 
sand. Therefore, the purpose of this first line of evidence is twofold: 
to define the broader connectivity of higher conductivity soils that 
might act as preferential flow pathways and to characterize the 
variability of the soil to guide collection of samples for the second 
line of evidence.
    EPA proposed that characterization of site hydrogeology must 
include all of the following: (1) Measurements of the hydraulic 
conductivity in the uppermost aquifer from existing monitoring wells 
and discussion of the methods used to obtain these measurements; (2) 
Subsurface samples collected to characterize site hydrogeology must be 
located around the perimeter of the surface impoundment at a spatial 
resolution sufficient to ensure that any regions of substantially 
higher conductivity have been identified; (3) Conceptual site models 
with cross-sectional depictions of site stratigraphy that include the 
relative location of the surface impoundment (with depth of ponded 
water noted), monitoring wells (with screening depths noted), and all 
other subsurface samples used in the development of the models; (4) 
Narrative description of site geological history; and (5) All data used 
in the conceptual site model summarized into easily readable graphs or 
tables. EPA did not receive any comments relevant to Sec.  
257.71(d)(1)(ii)(A)(4). Therefore, EPA is finalizing this requirement 
as proposed with updated numbering to reflect changes in the other 
regulatory text paragraphs. Discussion of comments on other provisions 
are provided in the following Units.
a. Measurements from Existing Wells
    EPA proposed at Sec.  257.71(d)(1)(ii)(A)(1) that the demonstration 
must include measurements of the hydraulic conductivity in the 
uppermost aquifer measured from existing monitoring wells and 
discussion of the methods used to obtain these measurements.
    One commenter stated that EPA should consider modifying or removing 
the requirement that uppermost aquifer hydraulic conductivity 
measurements must be measured from existing monitoring wells. They 
argued that there may be additional data points and locations that may 
be more representative than conductivity measurements taken from the 
existing well locations. The commenter requested that locations for 
these measurements be determined by the technical team preparing the 
demonstration and should not be limited to these prescriptive 
locations.
    The waste boundary is the point of compliance for all GWPS. These 
standards apply to all units subject to the existing regulations, 
including those submitting an ALD. Thus, the hydrogeologic conditions 
in the vicinity of the wells used to determine compliance are highly 
relevant. However, Sec.  257.71(d)(1)(ii)(A)(1) only establishes a 
minimum standard for the demonstration. Facilities can collect and 
incorporate additional data beyond this minimum in the demonstration, 
as

[[Page 72519]]

warranted to further delineate hydrogeologic conditions. Therefore, EPA 
made no amendment to the rule language in response to this comment.
b. Sampling at the Perimeter of a Surface Impoundment
    EPA proposed to require that subsurface samples must be collected 
to characterize site hydrogeology and must be located around the 
perimeter of the surface impoundment at a spatial resolution sufficient 
to ensure that any regions of substantially higher conductivity have 
been identified. In the proposal, EPA acknowledged that some data may 
already be available from previous investigations, such as sampling or 
logging done during the installation of monitoring wells or other 
subsurface evaluations. However, the Agency considered it likely that 
additional data would be necessary to provide adequate coverage of the 
subsurface.
    Environmental groups raised concerns that it would not be feasible 
for an owner or operator to collect enough site-specific data to allow 
for a determination that an existing alternate liner is protective. One 
commenter stated that site characterization at the necessary spatial 
resolution would require multiple rounds of sampling, might necessitate 
installation of additional monitoring wells, and would require far 
longer than allowed by this rule. Another went further and stated that 
no characterization of a site's hydrogeology and potential for 
infiltration will be able to prove that a nonconductive layer is 
continuous under the entire ash pond.
    EPA agrees that it is critical to adequately characterize potential 
transport beneath the unit but disagrees that it is not possible to 
collect sufficient data to characterize subsurface transport. For the 
subset of impoundments that rely on natural soils to limit contaminant 
transport, it is improbable that any high-conductivity soils present 
on-site are limited entirely to within the footprint of a unit. The 
long-term movement of both water bodies and glaciers tend to leave 
deposits all along the migration path. This is supported by 
observations across a wide range of depositional environments that 
layers of sand and clay are typically found in a ``shingled'' or 
``laterally offset'' fashion, rather than as a ``layer cake'' with one 
stacked neatly on top of the other.\14\ Thus, collection of samples 
from around the perimeter is expected to provide reliable information 
about both the variability of conditions underneath the impoundment and 
the potential for transport away from the impoundment. Even if isolated 
lenses of sand or other high-conductivity material were located 
entirely beneath the impoundment, these disconnected deposits would not 
negate the low conductivity of the surrounding clay because of a lack 
of connectivity. Finally, the surficial geophysical methods referenced 
by one of the same commenters can provide information on soils some 
distance away from the point of measurement. Depending on the specific 
geometry of a unit and the methods used, the data collected around the 
perimeter of the unit can also provide substantial coverage of the 
soils beneath the unit. Based on these facts, EPA concludes that data 
collected from around the waste boundary can also provide reasonable 
estimates of the variability beneath the unit for the purposes of an 
alternate liner demonstration.
---------------------------------------------------------------------------

    \14\ U.S. EPA. 2017. ``Best Practices for Environmental Site 
Management: A Practical Guide for Applying Environmental Sequence 
Stratigraphy to Improve Conceptual Site Models.'' EPA/600/R-17/293. 
Prepared by the Office of Research and Development. Cincinnati, OH. 
September.
---------------------------------------------------------------------------

    Although fieldwork may take some time, it will not begin from 
scratch. Facilities allowed to progress to the demonstration step will 
have already confirmed that there is adequate subsurface 
characterization available to appropriately site the existing 
groundwater wells. These data will inform subsequent sampling efforts. 
In the proposal, EPA contemplated the potential for this line of 
evidence to also identify the need for additional wells to address 
previously unidentified regions of high conductivity soil. However, the 
finalized application step requires documentation that the existing 
network is sufficient to ensure detection of contamination in the 
uppermost aquifer. Therefore, this line of evidence will not involve 
the time-consuming process of installing and sampling new monitoring 
wells. The standardized geophysical survey methods discussed both in 
the proposal and raised by commenters can be conducted within the 
required timeframe, even if more than one round of data collection is 
ultimately required.
    Therefore, EPA is finalizing the requirement at Sec.  
257.71(d)(1)(ii)(A)(2) without change from the proposal. The final rule 
requires that measurements of the variability of subsurface soil 
characteristics must be collected from around the perimeter of the 
impoundment to identify any regions of substantially higher hydraulic 
conductivity.
c. Sampling Methods
    In the proposal, EPA discussed that traditional geologic mapping, 
that relies primarily on the Unified Soil Classification System, has 
been found to underestimate the prevalence and interconnectedness of 
soil deposits that may act as preferential flow pathways. EPA cited to 
a practical guide on the use of environmental sequence stratigraphy and 
facies models to aid in characterization of subsurface 
heterogeneity.\15\ EPA noted that there are a number of methods 
available that can provide useful data at the necessary spatial 
resolution, such as direct-push logging (e.g., cone penetration test) 
and borehole geophysical logging. However, EPA did not propose the use 
any specific methods, nor did the Agency place explicit restrictions on 
the types of methods available.
---------------------------------------------------------------------------

    \15\ U.S. EPA. 2017. ``Best Practices for Environmental Site 
Management: A Practical Guide for Applying Environmental Sequence 
Stratigraphy to Improve Conceptual Site Models.'' EPA/600/R-17/293. 
Prepared by the Office of Research and Development. Cincinnati, OH. 
September.
---------------------------------------------------------------------------

    Several industry commenters and one environmental group expressed 
concern that the proposal unnecessarily required invasive sampling 
methods to collect the necessary data on conditions below the ground 
surface. Multiple commenters identified specific methods, such as 
electrical-resistivity tests, as alternate methods that could provide 
relevant information. One commenter further pointed to the Interstate 
Technology and Regulatory Council website on advanced site 
characterization tools.\16\
---------------------------------------------------------------------------

    \16\ https://asct-1.itrcweb.org/.
---------------------------------------------------------------------------

    EPA acknowledges that the language used in the proposal could be 
taken to imply that invasive sampling is the only type of method 
allowed for this line of evidence, but EPA did not intend to restrict 
the methods available for use in this way. EPA agrees that surficial 
(or non-invasive) sampling can provide useful information, though these 
methods often require correlation or a combination of qualitative and 
quantitative interpretation to properly interpret the data. These 
surface geophysical tools tend to be most powerful when used in 
combination with other methods.
    Therefore, for clarity, EPA is finalizing an amended version of 
Sec.  257.71(d)(1)(ii)(A)(3). The final rule specifies that 
characterization of subsurface variability must be conducted with 
recognized and generally accepted methods. Facilities must document how 
the combination of methods relied upon provides reliable

[[Page 72520]]

information at a spatial resolution necessary to adequately 
characterize the variability of subsurface conditions that will control 
contaminant transport.
d. Sample Depth and Spacing
    EPA discussed in the preamble of the proposed rule that samples 
should extend down to the top of the natural water table or at least 20 
feet beneath the bottom of the nearest water body (to identify 
potential for upwelling), whichever is greater, to ensure that any 
potential preferential flow pathways have been identified. EPA also 
discussed that the initial soil samples collected around the perimeter 
of the unit should be spaced at a distance no greater than 200 feet 
apart in low-conductivity soils. This distance reflects recommendations 
by the U.S. Department of Transportation (U.S. DOT) for the 
characterization of unknown subsurface environments.\17\ If there is 
indication from the site history, collected soil samples, or other 
sources that high-conductivity deposits may be present at widths 
narrower than 200 feet, then even finer sample spacing may be 
warranted. EPA stated that the demonstration must substantiate why the 
number and types of samples collected are sufficient to capture any 
heterogeneity of the subsurface and why the data used to estimate 
contaminant fate and transport through the subsurface are 
representative of the variability identified. If regions of higher 
conductivity are present around the site, the potential impacts of 
preferential flow on groundwater concentrations will need to be 
considered in the demonstration. Furthermore, if regions of 
preferential flow are identified in otherwise low-conductivity soils 
that are not adequately captured by the existing monitoring well 
network, then re-evaluation of the placement of monitoring wells around 
the waste boundary would be warranted to address these gaps.
---------------------------------------------------------------------------

    \17\ U.S. DOT. 2006. ``Geotechnical Aspects of Pavement: 
Reference Manual/Participant Workbook.'' FHWA NHI-05-037. Prepared 
by the Federal Highway Administration. Washington, DC. May.
---------------------------------------------------------------------------

    Many commenters argued that the depth and spacing of samples 
discussed in the preamble was overly strict. No commenters raised issue 
with the rationale for the proposed sample depths. However, one 
commenter argued that characterization down to the groundwater table is 
unnecessarily burdensome for sites with deep groundwater. This 
commenter stated that if the first 100 feet of the soil overlying the 
aquifer is not sufficient to prevent contamination of groundwater, then 
the next 100 feet is unlikely to alter that fact. Several commenters 
raised questions about the rationale for the proposed sample spacing. 
One commenter pointed out that EPA has previously written that the 
number of borings necessary to characterize soils is dependent on the 
geological complexity, size, potential areal extent of a release, and 
the importance of defining small-scale discontinuities in formation 
materials.\18\ Many others pointed out that the U.S. DOT guidance 
referenced in the preamble is not directly related to waste disposal 
and that the guidance also states that the spacing and depth of the 
borings should be based on an evaluation of available information.\19\ 
Most of these commenters requested further justification for the 
criteria for sample spacing.
---------------------------------------------------------------------------

    \18\ U.S. EPA. 1989. ``Interim Final RCRA Facility Investigation 
(RFI) Guidance Volume II Of IV: Soil, Ground Water And Subsurface 
Gas Releases.'' EPA 530/SW-89-031. OSWER Directive 9502.00-6D. 
Prepared by the Office of Solid Waste. Washington, DC. May.
    \19\ U.S. DOT. 2006. ``Geotechnical Aspects of Pavement.'' FHWA 
NHI-05-037. Prepared by the Federal Highway Administration. 
Washington, DC. May.
---------------------------------------------------------------------------

    EPA generally agrees with commenters that the exact depth and 
spacing of samples should be informed by site conditions. The 
discussion provided in the proposal was intended to define an initial 
depth and spacing of samples that would ensure identification of 
subsurface variability at these sites, not to impose this exact 
sampling regime at every site. Instead, EPA intended for facilities to 
document why the number and types of samples collected are sufficient 
to capture the heterogeneity of the subsurface if sampling deviated 
from these specifications. Such documentation would not provide 
additional useful information if all sampling was pre-determined. EPA 
believes these baseline requirements are warranted because there will 
be no time for facilities to fill data gaps in the characterization of 
the site if a demonstration is found to be insufficient. These 
requirements also help clarify the level of documentation expected as 
part of the demonstration.
    As discussed, the 200 feet spacing was based on a U.S. DOT 
publication that provides a review of recommended practices for 
installation of pavement from a geotechnical perspective based on 
guidelines from textbooks, several state agencies, and the Federal 
Highway Administration. Commenters are correct that a primary focus of 
the publication is the stiffness and strength of the soil; however, it 
also accounts for soil permeability and the presence of 
discontinuities, fractures, and fissures of subsurface formations, 
which are relevant to the demonstration. The minimum spacing was 
selected from this publication based on the professional judgement of 
Agency staff, who have considerable experience on this topic from work 
at cleanup sites across the country. For all these reasons, EPA 
continues to believe that selected minimum spacing is relevant and 
appropriate. Notably, no commenters indicated that an initial 200 feet 
spacing was too wide apart to effectively characterize soil, nor did 
any commenters identify another standard believed to be more directly 
applicable.
    In response to these comments, EPA is finalizing Sec.  
257.71(d)(1)(ii)(A)(4) with amendments to make clear that facilities 
must document why the specific number, depth, and spacing of samples 
collected are sufficient to reflect the variability of subsurface soils 
if 1) samples are advanced to a depth less than the top of the 
groundwater table or 20 feet beneath the bottom of the nearest water 
body, whichever is greater, or 2) samples are spaced farther apart than 
200 feet around the surface impoundment perimeter.
e. Conceptual Model
    EPA proposed at Sec.  257.71(d)(1)(ii)(A)(3) that as part of the 
first line of evidence, facilities must provide conceptual site models 
with cross-sectional depictions of site stratigraphy that include the 
relative location of the surface impoundment (with depth of ponded 
water noted), monitoring wells (with screening depths noted), and all 
other subsurface samples used in the development of the models.
    One commenter stated that the conceptual models should also include 
``all relevant hydraulic information, including depth to saturated 
zones, piezometric surface elevation, withdrawal points, recharge and 
discharge areas. Based on groundwater and contaminant flow model 
projections, the cross sections should extend a sufficient distance 
from the surface impoundment to incorporate the influence of such 
features on the site-vicinity hydrogeology.''
    EPA agrees that the depiction of site hydrology on these diagrams 
is important. Although some data identified by the commenter are 
already required as part of other diagrams, inclusion here allows both 
an alternate view of these data (cross-sectional instead of aerial) and 
a more complete understanding of the relationship between site geology 
and subsurface transport. At the same time, requiring

[[Page 72521]]

facilities to depict the full variability of groundwater depth and flow 
in these cross-sections could dramatically increase the total number of 
diagrams needed without providing much additional clarity. Instead, EPA 
believes it is more important for this set of diagrams to depict the 
range of hydrologic conditions encountered at the site.
    Therefore, in response to these comments, EPA is finalizing Sec.  
257.71(d)(1)(ii)(A)(5) with an amendment that each cross-sectional 
diagram must also include demarcation of, at a minimum, (1) the upper 
and lower limits of the uppermost aquifer across the site, (2) the 
upper and lower limits of the depth to groundwater measured from 
facility wells if the uppermost aquifer is confined, and (3) both the 
location and geometry of any nearby points of groundwater discharge or 
recharge (e.g., surface water bodies, wells) with potential to 
influence groundwater depth and flow measured around the unit.
2. Line of Evidence #2--Potential for Infiltration
    The second line of evidence that EPA proposed at Sec.  
257.71(d)(1)(ii)(B) would require evaluation of the potential for 
infiltration through any liners and underlying soils that control the 
release and transport of leachate by either in-situ sampling, or by 
conducting an analysis of the soil-based liner and underlying soil of 
the unit through laboratory testing. EPA discussed in the preamble that 
the purpose of this line of evidence is to provide a reasonable 
estimate of the rate at which contaminants may be released and 
transported to groundwater over time. However, EPA also questioned 
whether collection of in-situ data would be feasible for facilities.
    EPA received comments from multiple facilities agreeing that 
collection of data from beneath the surface impoundment could be 
unnecessarily onerous and may disturb the integrity of the surface 
impoundment. One environmental group stated that field measurements of 
hydraulic conductivity were preferable because laboratory measurements 
have the potential to differ from field measurements. This commenter 
stated that the hydraulic conductivity of geosynthetic clay liners can 
be impacted by a variety of factors in the field that may not be 
adequately addressed in the lab, citing to several studies purported to 
raise concerns both that laboratory tests were unreliable and that the 
leaching behavior of clays were too poorly understood to reliably 
measure in the lab.
    EPA agrees with commenters who stated that in-situ analysis of 
liner performance while the unit operates would be impracticable. 
Installation of a leachate collection device, such as lysimeter, 
beneath the impoundment to measure releases in real time risks 
disruption of the liner. In addition, because the current state of the 
liner cannot be directly observed or measured during operation, it is 
not possible to determine whether such measurements reflect the long-
term interactions between the liner and CCR leachate. Therefore, EPA is 
removing the provision that allowed for in-situ sampling of hydraulic 
conductivity.
    EPA disagrees that the studies provided by the commenter raise 
wider concerns about either the general reliability and reproducibility 
of laboratory methods or the specific ability to accurately measure 
hydraulic conductivity in a laboratory setting. The Agency's review of 
the cited articles found that excerpts quoted by the commenter did not 
fully reflect the context or conclusions of the studies, that the 
conclusions the commenter had drawn from some studies were incorrect, 
and that many of the studies cited had limited or unclear applicability 
to CCR surface impoundments. Specifically:
     The first study quoted by the commenter evaluated the 
precision among labs for hydraulic conductivity measurements of fine-
grained soils using Method C of ASTM D5084-10.\20\ From this study the 
commenter drew the quote, ``many of the laboratories in the study did 
not follow the test method precisely.'' However, the authors of this 
study concluded that the variability of results between labs was not 
sensitive to these deviations from protocol. Further, the authors found 
that ``hydraulic conductivity can be measured within a factor of 2 for 
the 10-\6\ cm/s range, a factor of 1.5 for the 
10-\6\ cm/s range, and a factor of 4 for the 
10-\9\ cm/s range.'' These results do not support wider 
concerns about laboratory reproducibility raised by the commenter. 
First, the commenter fails to acknowledge that measurement uncertainty 
is an inherent part of any data collection effort and they provide no 
evidence that field measurements would yield appreciably lower 
variability. Second, the magnitude of variability identified in the 
study is minor compared to the multiple orders of magnitude over which 
soil conductivity can vary. Thus, this source of variability will 
become less important in lower conductivity soils. Finally, the 
commenter does not acknowledge that uncertainties can be managed within 
an evaluation to ensure that long-term contaminant release and 
transport are not underestimated. For example, under the requirements 
of this rule, facilities are required to measure the hydraulic 
conductivity of subsurface soils saturated with CCR leachate, which 
will simulate the highest conductivity possible for that soil.
---------------------------------------------------------------------------

    \20\ Benson, C.H. and N. Yesiler, 2016. ``Variability of 
Saturated Hydraulic Conductivity Measurements Made Using a Flexible-
Wall Permeametter,'' Geotechhnical Testing Journal. 39(3):476-491.
---------------------------------------------------------------------------

     A second study referenced by the commenter compared 
concentrations in CCR leachate with two different EPA methods, the 
synthetic precipitation leaching procedure (SPLP; Method 1312) and 
Leaching Environmental Assessment Framework (LEAF, Method 1313).\21\ 
From this study the commenter pointed to the statement that ``SPLP 
results were highly variable when compared to the LEAF data.'' The 
commenter indicated that this was evidence that laboratory tests were 
not reliable. EPA disagrees. The study authors discussed potential 
causes of observed differences between the two methods, which they 
attributed primarily to the different extraction acids used by the two 
methods, a conclusion supported by the findings of previous studies. 
This is reasonable because the two leaching tests are designed to 
represent somewhat different environmental scenarios. There is no 
indication that either method returned erroneous results for the 
specified conditions. EPA has subjected the LEAF methods to extensive 
inter-laboratory validation and has great confidence in the results of 
these methods.\22\ The Agency has also emphasized that the data from 
leaching tests must be considered carefully to ensure that the test 
conditions provide relevant information about actual environmental 
conditions. Therefore, the commenter's assertion that these results 
raise concerns about the reliability of laboratory methods is 
incorrect.
---------------------------------------------------------------------------

    \21\ da Silva, E.B., S. Li, L.M. de Oliveira, J. Gress, X. Dong, 
A.C. Wilkie, T. Townsend, and S.Q. Ma. 2018. ``Metal Leachability 
from Coal Combustion Residuals under Different pHs and Liquid/Solid 
Ratios.'' Journal of Hazardous Materials. 341:66-74.
    \22\ U.S. EPA. 2012. ``Interlaboratory Validation of the 
Leaching Environmental Assessment Framework (LEAF) Method 1313 and 
Method 1316.'' EPA 600/R-12/623. Prepared by tthe Office of Research 
and Development. September.
---------------------------------------------------------------------------

     The commenter cited a number of studies as evidence that 
in-situ conditions exist that cannot be reliably

[[Page 72522]]

measured. However, many of these studies do not directly address clay 
liners or even waste disposal, focusing instead on issues such as 
climate change. Others evaluated liners exposed to extreme conditions, 
such as sustained operating temperatures above 100 [deg]F and high 
ammonia concentrations. The commenter provides no indication beyond the 
ancillary citations how these issues are germane. Nevertheless, the 
commenter concluded that ``in-situ conditions are very complex and we 
do not yet have enough understanding of how these complexities affect 
CCR leachability to ensure that we make accurate models in the lab.'' 
Yet, this assertion does not comport with the available literature that 
shows reasonable agreement can be achieved between field and lab 
measurements when units are well constructed.\23\
---------------------------------------------------------------------------

    \23\ U.S. EPA. 2002. ``Assessment and Recommendations for 
Improving the Performance of Waste Containment Systems.'' EPA/600/R-
02/099. Prepared by the Office of Research and Development. 
December.
---------------------------------------------------------------------------

    EPA maintains that laboratory analysis is the preferred means to 
measure hydraulic conductivity of soil for the purposes of an ALD. 
Field analysis typically involves use of an infiltrometer or 
permeameter to measure the rate that water infiltrates into the 
uppermost layer of soil. These methods are generally not designed to 
account for the complexities associated with this type of 
demonstration. First, the soil to be tested may be located some 
distance below the ground surface, which will be difficult to isolate 
and reliably test in the field. Second, field tests are generally 
designed to use water, rather than a high-ionic strength leachate. As a 
result, these methods are not designed to collect the effluent needed 
to track system chemistry. Third, the potentially long test run times 
could make it difficult to control for environmental variables, such as 
evaporation. Therefore, to ensure reliable implementation of test 
methods and consistency between the various samples, EPA concludes that 
all samples for hydraulic conductivity should be measured in a 
controlled laboratory setting.
    Therefore, EPA is finalizing the requirement at Sec.  
257.71(d)(1)(ii)(B) with an amendment that removes the option for in 
situ sampling. The final rule now specifies that facilities must send 
all samples of the soil-based liner components and/or naturally-
occurring soil for analysis under controlled conditions in a certified 
laboratory. Samples must be analyzed using a recognized and generally 
accepted methodology. Facilities must document in the demonstration how 
the selected test method is designed to simulate field conditions 
(e.g., hydraulic head, effective stress).
    In the proposal, EPA stressed that it is critical that laboratory 
tests are designed to reflect site conditions to ensure the data 
generated reflect real-world and long-term operating conditions. EPA 
provided several examples of potentially relevant site conditions. EPA 
received a number of comments related to several of these and other 
site conditions. Discussion of the site conditions and the specific 
comments received is provided in the following Units of this preamble.
a. Number and Location of Samples
    EPA did not provide specific discussion in the proposal about the 
required number, depth, or spacing of samples for analysis of hydraulic 
conductivity for the second line of evidence. Instead, EPA stated in 
the first line of evidence that samples must be located around the 
perimeter of the surface impoundment at a spatial resolution sufficient 
to ensure that any regions of substantially higher conductivity have 
been identified. EPA had intended for the variability of the 
hydrogeology identified in the first line of evidence to inform the 
number and location of samples analyzed for the second line of 
evidence.
    Based on comments received, EPA believes that commenters generally 
assumed EPA had proposed that the location of samples for hydraulic 
conductivity must coincide with samples collected for the first line of 
evidence. As such, EPA considers all general comments requesting that 
the frequency of data collection be based on the variability of the 
site geology to be equally relevant here.
    EPA did not envision that samples collected to characterize 
hydraulic conductivity would exactly match the number or location of 
those collected for the first line of evidence. For example, as 
discussed in Unit III.C.1.b of this preamble, this rule also allows for 
use of non-intrusive methods to support the first line of evidence. 
Because non-intrusive methods do not advance equipment into the soil, 
they do not allow for simultaneous collection of subsurface soil 
samples. The combination of methods used to characterize site 
hydrogeology may identify regions of subsurface variability some 
distance away from the point of measurement. Therefore, facilities 
should instead use the information available on subsurface variability 
from the first line of evidence to inform the number and location of 
samples for the second line of evidence.
    Therefore, for clarity and consistency with the first line of 
evidence, EPA is finalizing a requirement at Sec.  
257.71(d)(1)(ii)(B)(1) that facilities are required to document where 
samples were collected around the surface impoundment and how the 
number, depth, and spacing of these samples (1) are supported by the 
data collected for the first line of evidence and (2) are sufficient to 
capture the variability of hydraulic conductivity for the soil-based 
liner components and/or naturally occurring soil.
b. Permeant Liquid
    EPA discussed in the proposal that tests used to estimate hydraulic 
conductivity need to use a permeant liquid that reflects the 
composition of the infiltrating surface impoundment porewater. The 
method must account for the chemistry of CCR porewater that can have 
both extreme pH and high salinity. Extreme pH may dissolve key 
components of the soil structure, while high salinity may result in 
interlayer shrinkage of clays, both of which can result in higher 
hydraulic conductivity. Use of a non-representative liquid (e.g., 
deionized water) as the permeant liquid or pre-hydrating the clay may 
actually decrease the conductivity of clay through swelling and result 
in a lower measured conductivity than would actually occur in the 
field.
    EPA received no adverse comments on this topic. One commenter 
raised concern that exposure to CCR leachate can adversely affect the 
integrity of a liner, though this commenter made no reference to the 
preamble discussion. Instead, the commenter cited to multiple studies 
purported to show that CCR leachate can adversely affect geosynthetic 
clay liners and that pre-hydrating samples with deionized water may 
underestimate long-term conductivity.
    As discussed in the proposal and above, EPA agrees that the effects 
of leachate chemistry on long-term soil conductivity are potentially 
significant. Therefore, EPA is finalizing a requirement at Sec.  
257.71(d)(1)(ii)(B) that the liquid used to pre-hydrate the clay and 
measure long-term hydraulic conductivity must reflect the pH and major 
ion composition of the impoundment porewater.
c. Thixotropic Effects
    EPA raised concern in the proposal that preparation of samples 
intended to reflect compacted soil liners for testing may result in the 
soil becoming temporarily less permeable as a result of

[[Page 72523]]

thixotropic behavior. EPA previously raised the potential for the 
structure of thixotropic materials, such as certain clays, to become 
temporarily more dispersed when agitated, which might limit flow 
through interstitial pores and make it more difficult for water to 
infiltrate.\24\ EPA was concerned that the material will gradually 
become more permeable as it is allowed to rest and return to its 
original state. Therefore, EPA stated in the proposal that compacted 
samples should be allowed to rest for sufficient periods prior to 
testing to reflect the long-term behavior of the soil in the field.
---------------------------------------------------------------------------

    \24\ U.S. EPA. 1986. ``Design, Construction, and Evaluation of 
Clay Liners For Waste Management Facilities.'' EPA/530-SW-86-007-F. 
Prepared for the Office of Solid Waste and Emergency Response. 
Washington, DC.
---------------------------------------------------------------------------

    EPA received no comments that expressed support for this 
requirement. One commenter questioned whether thixotropy is a relevant 
consideration and if a ``rest period'' is actually needed to provide a 
realistic measurement of hydraulic conductivity. This commenter pointed 
to multiple studies that found minimization of void spaces in the soil 
macrostructure was a key control on hydraulic conductivity. Based on 
this literature, the commenter concluded that the microscale structure 
described with terms such as ``dispersed'' or ``flocculated'' is not a 
major concern.
    The literature provided by the commenter indicates that effects 
from thixotropy are not a major concern in the measurement of hydraulic 
conductivity. EPA acknowledges that this topic is not raised in more 
recent literature discussed as part of this rulemaking. Similarly, none 
of the standardized tests for hydraulic conductivity reviewed by EPA 
specifies a need for an extended rest period. In addition, studies 
conducted more recently by EPA and others have obtained good agreement 
between measurements in the lab and field for many compacted, low-
conductivity soils without a rest period. Finally, this requirement has 
the potential to add a considerable amount of time to an already time-
intensive analysis. For all these reasons, EPA concludes that the 
available evidence does not support finalization of this provision.
d. Natural Soil Structure
    EPA discussed in the proposal that preparation for samples intended 
to reflect the naturally-occurring soils beneath the surface 
impoundment for testing may result in the soil becoming permanently 
less permeable by disturbing the natural structure of the soil and 
eliminating voids and other features that may act as conduits for 
infiltration in the field. Failure to preserve the structural integrity 
of such samples could result in a lower measured conductivity than 
would actually occur in the field because it results in greater 
compaction or consolidation than exists in the field. EPA pointed out 
that standardized methods have been developed to obtain undisturbed 
soil samples.
    EPA received no comments relevant to this topic. Therefore, EPA is 
finalizing a requirement at Sec.  257.71(d)(1)(ii)(B)(3) that 
facilities must ensure that samples intended to represent the hydraulic 
conductivity of naturally-occurring soils (i.e., not mechanically 
compacted) are handled in a manner that will ensure the macrostructure 
of the soil is not physically disturbed during collection, transport, 
or analysis (e.g., initial saturation). Facilities must provide 
documentation of the measures taken to ensure the integrity of the 
samples relied upon.
e. Test Termination Criteria
    EPA discussed that the termination point of a test must be 
established at a point that ensures the long-term behavior of the liner 
is accurately reflected. Some tests for hydraulic conductivity stop 
after the inflow and outflow rates equilibrate or after a specified 
volume of water has passed through the soil. However, these metrics may 
not be sufficient to identify the reactions that can occur between the 
soil and liquid (e.g., exchange of adsorbed cations). Some metrics that 
more directly address the chemistry of the soil-leachate interactions 
include equilibration of electrical conductivity and pH. Failure to run 
the test on a timeframe relevant to the chemical reactions of interest 
may result in a lower measured conductivity than would actually occur 
in the field.
    One facility stated that the proposed hydraulic conductivity 
testing is difficult, time-consuming, and not commonly conducted. The 
facility asserted that the information obtained from such tests would 
not significantly inform a determination of whether the impoundment is 
protective. Another commenter suggested two methods as most appropriate 
for use in the demonstration: ASTM D6766 (Standard Test Method for 
Evaluation of Hydraulic Properties of Geosynthetic Clay Liners 
Permeated with Potentially Incompatible Liquids) and ASTM D7100 
(Standard Test Method for Hydraulic Conductivity Compatibility Testing 
of Soils with Aqueous Solutions). This commenter noted that both 
methods include termination criteria based on chemical equilibrium.
    EPA acknowledges that it can take considerable time for hydraulic 
conductivity tests to meet termination criteria, and that criteria 
based on chemical equilibrium may require more time than those based on 
other metrics. However, the Agency disagrees that these tests provide 
no useful information. By allowing the chemistry of the system to reach 
equilibrium, it ensures that the long-term effects of leachate 
chemistry on the soil are adequately characterized. High ionic strength 
liquids have been shown to increase the long-term hydraulic 
conductivity of some soil materials by orders of magnitude compared to 
deionized water. The fact that these types of tests have been uncommon 
does not negate their importance.
    EPA agrees that the two methods referenced by the second commenter 
are more appropriate for use in the demonstration than ASTM D5084, 
which EPA provided as an example in the preamble. However, the two 
methods referenced by the commenter identify somewhat different 
termination criteria based on solution chemistry. While one method 
identifies only equilibrium for electrical conductivity, the other 
further identifies pH, concentrations of unspecified solutes, and/or 
the dielectric constant. Electrical conductivity and pH provide a means 
to identify changes in the dominant solution chemistry. In addition, 
both can be tested for rapidly and easily. That is why EPA believes 
they serve as practical indicators for the hydraulic conductivity 
tests. While other criteria, such as specific solute concentrations, 
can provide further information on how the leachate interacts with the 
soil (e.g., which ions are substituted on the soil surface), EPA has 
not seen evidence that these additional parameters will identify 
significant changes in the solution chemistry that electrical 
conductivity and pH would not.
    Therefore, EPA is finalizing a requirement at Sec.  
257.71(d)(1)(ii)(B)(4) that any test for hydraulic conductivity relied 
upon must include, in addition to other relevant termination criteria 
specified by the method, criteria that equilibrium has been achieved 
within acceptable tolerance limits between the inflow and outflow for 
both electrical conductivity and pH.
3. Additional Lines of Evidence
    EPA solicited comment on whether there are any additional lines of 
evidence that should be included as part of the demonstration. Various 
industry groups, individual facilities,

[[Page 72524]]

environmental groups, and states all proposed additional factors to be 
considered. These factors included whether a unit had individual liner 
components that met the standard of the CCR regulations, previous 
certification of performance from states or professional engineers, and 
the impact of closure on releases. These are discussed in more detail 
in the following Units of this preamble.
a. Presence of Geomembrane Liner
    One commenter requested that EPA waive the demonstration 
requirement for units that have at least a 60-mil geomembrane liner, 
but do not meet the remaining requirements to be considered a lined 
unit. This and another commenter indicated that a successful initial 
application combined with decades of operation without any indication 
the unit has adversely affected groundwater should be sufficient 
evidence that the liner is protective.
    EPA emphasizes that the intent of a demonstration is to 
characterize the potential for future groundwater exceedances. It can 
take years or even decades for leachate released from an impoundment to 
reach downgradient wells. Thus, the fact that a unit has not yet 
triggered corrective action does not mean it is not possible at some 
point in the future. This is why groundwater monitoring is required at 
all units. Furthermore, as part of the demonstration, facilities are 
required to test the hydraulic conductivity of the soil component of 
the composite liner to demonstrate its long-term performance when 
exposed to leachate. If the soil liner beneath a geomembrane liner is 
found to be ineffective, then imperfections in the geomembrane liner 
may lead to unimpeded flow of leachate into the subsurface. Based on 
this, EPA concludes that information on the subsurface soil component 
is a necessary line of evidence for all impoundments. Therefore, both 
an initial application and final demonstration must be submitted as 
part of an alternate liner demonstration for any impoundment.
b. Previous Certification
    Multiple commenters requested that EPA give deference to a previous 
certification by a professional engineer or prior approval by a state 
regulatory authority when determining whether to approve a 
demonstration. Some commenters noted that their states require quality-
assurance/quality-control (QA/QC) plans for liner construction and 
maintenance be included in the permit and that their surface 
impoundment liner was inspected and certified by a licensed 
professional engineer with appropriate expertise. One commenter 
asserted that this helps establish a presumption that a surface 
impoundment liner is adequately protective. However, none of the 
commenters elaborated on how the Agency should assign weight to such 
findings as part of the larger review.
    EPA agrees that documentation about the quality of liner 
construction is necessary to prove that the surface impoundment has 
been well constructed and so has the potential to be protective. That 
is why information on construction quality must be provided upfront in 
the application step. However, the fact that a unit meets an 
unspecified design standard does not guarantee that particular standard 
will be protective in the long term. A purpose of the demonstration 
step is to document that the design of an alternate liner will remain 
protective in the long-term when exposed to CCR leachate. EPA cannot 
outright substitute a prior approval by either a qualified professional 
engineer (PE) or state agency for the comprehensive alternate liner 
demonstration required by this rule. State requirements can vary in 
both scope and specificity and EPA does not have a reliable record of 
what was considered as part of these reviews or how it aligns with the 
requirements of this rule. To the extent that previous findings by a PE 
or state authority details how a unit achieves the requirements of this 
rule, EPA will consider the rationale provided as part of the larger 
demonstration. However, this rationale does not substitute for 
providing any of the data or other underlying documentation required by 
this rule. Therefore, EPA made no changes to the rule in response to 
these comments.
c. Consideration of Unit Closure
    One state recommended that the existence of plans to dewater the 
surface impoundment and install an impermeable cap be included as an 
additional line of evidence in the demonstration. The commenter noted 
such actions could alter the hydrogeologic model and/or reduce 
groundwater impacts. However, the commenter did not elaborate on how 
the Agency should weigh such information as part of the larger review.
    The intent of the determination is to document the potential 
environmental impacts associated with continued operation of the unit. 
Although the installation of an impermeable cap would reduce 
infiltration, such actions would not be feasible during operation and 
are already required of all surface impoundments as part of closure. 
Therefore, it is not clear how this could be incorporated as a line of 
evidence. Therefore, EPA concludes that is not a relevant line of 
evidence and made no changes to the regulations in response to this 
comment.
4. Incorporation of Lines of Evidence Into Demonstration
    EPA proposed that the data collected for the two lines of evidence, 
characterization of site hydrogeology and potential for infiltration, 
must be incorporated into the final demonstration. Each one provides 
different, site-specific data necessary to understand the potential for 
continued operation of the unit to adversely affect groundwater in the 
future. Consideration of future effects will necessitate some amount of 
fate and transport modeling. EPA acknowledged that the type of model 
used will depend on the complexity of the site. Regardless of the 
modeling approach used, all of the data incorporated into the 
calculations must be documented and justified.
    EPA received some general comments related to the incorporation of 
the lines of evidence into the demonstration. One commenter stated that 
groundwater and contaminant flow models should be developed by drawing 
on the data used for the conceptual site models and run using various 
scenarios to ensure adequate consideration of a range of operating and 
site conditions. A second commenter stated that the magnitude of 
releases from surface impoundments is determined by a myriad of 
variables and reducing these systems to only one (i.e., hydraulic 
conductivity) fails to capture this complexity, increasing the chance 
of mischaracterizing the probability of groundwater contamination.
    EPA agrees with the first commenter that it is critical that 
facilities document how any data relied upon adequately reflect the 
range of variability in operational and environmental conditions at and 
around the surface impoundment to ensure that high-end risks are not 
underestimated. EPA disagrees with the second commenter that the 
required lines of evidence are not adequate to identify this 
variability and the potential for adverse effects to groundwater. 
Although the effective hydraulic conductivity of the engineered liner 
and/or naturally occurring soil is one of the most important 
parameters, this does not mean other parameters are not also important 
or accounted for in the demonstration. EPA previously identified a list 
of highly sensitive

[[Page 72525]]

model parameters in the 2014 Risk Assessment. Data for some of these 
parameters are already available through the existing groundwater 
monitoring program (i.e., depth to groundwater, hydraulic gradient). 
Data for others will be collected for the two lines of evidence 
required by this rulemaking (i.e., infiltration rate, hydraulic 
conductivity). EPA did not propose to require the remaining parameters 
to be collected on a site-specific basis (i.e., leachate concentration, 
sorption coefficients) because a national-scale record of these 
parameters already exists for the constituents modeled in the 2014 Risk 
Assessment. To avoid the need for entirely new, site-specific risk 
assessments that evaluate impacts to both groundwater and surface 
water, facilities will need to consider the same high-end leachate 
concentrations that the clay-lined units were found unable to contain 
in order to demonstrate that the alternate liner performs materially 
better. Therefore, EPA is requiring that the owner or operator draw 
from the existing risk record to characterize leachate chemistry and 
behavior in the demonstration. Use of these data will help mitigate any 
uncertainties about the representativeness of the sampled ash or how 
conditions might change in the future. Altogether, this will ensure 
confidence that GWPS will not be exceeded.
    EPA is finalizing a requirement at Sec.  257.71(d)(1)(ii)(C) that 
facilities must incorporate the site-specific data collected for the 
two lines of evidence, characterization of site hydrogeology and 
potential for infiltration, into a mathematical model used to calculate 
the potential groundwater concentrations that may result in 
downgradient wells as a result of the impoundment. EPA is amending the 
proposed regulatory text to incorporate greater specificity based on 
the discussion in the preamble to the proposed rule. Accordingly, the 
final regulation specifies that facilities must also, where available, 
incorporate the national-scale data on constituent concentrations and 
behavior provided by the existing risk record. Where an existing record 
is not available, the owner or operator must justify how the data used 
are adequate to reflect high-end concentrations and behavior at the 
site. The regulation also specifies that application of the model must 
account for the full range of current and potential future conditions 
at and around the site to ensure that high-end groundwater 
concentrations have been effectively characterized. All of the data and 
assumptions incorporated into the model must be documented and 
justified.
a. Specific Models Used
    EPA discussed in the proposal that the model used may vary based on 
the complexity of a particular site. More complex sites may merit the 
use of a probabilistic fate and transport model similar to that used in 
the 2014 Risk Assessment. If a site is less complex (e.g., homogenous, 
low-conductivity soil), then more deterministic calculations may be 
sufficient to demonstrate that no adverse effects will occur. 
Regardless of the approach used, all of the data incorporated into the 
calculations must be documented and justified.
    One commenter expressed concerns that the EPA Composite Model for 
Leachate Migration with Transformation Products (EPACMTP) is not able 
to fully represent the complexities of site conditions and so should 
not be allowed as the basis for decisions about future unit 
performance. EPACMTP was previously used by the Agency in the 2014 Risk 
Assessment and later by EPRI in a white paper submitted to EPA to show 
that some unlined surface impoundments can also be protective. This 
commenter raised two specific concerns about EPACMTP. First, that the 
model treats the subsurface environment as homogenous and so is not 
able to reflect variable hydraulic conductivity in any individual model 
run. Second, that the model cannot account for constituent mass sinks 
beyond the unit, such as discharge of groundwater to water bodies.
    The Agency agrees that there can be instances where EPACMTP is not 
the model best suited to represent the complexities of a particular 
site. EPA discussed one such example in a memorandum included in the 
docket for the proposed rule.\25\ Based on these considerations, EPA 
did not propose to require use of EPACMTP or any other specific model 
in a demonstration. However, this does not mean that use of EPACMTP is 
never appropriate. EPA was cognizant of the limitations of the model 
when preparing the 2014 Risk Assessment and took steps to ensure that 
risks were neither underestimated nor overestimated. To address 
heterogeneity in the subsurface, EPA conducted a probabilistic analysis 
that varied the hydraulic conductivity based on the range of soil types 
identified around a facility. To address losses to nearby water bodies, 
EPA applied a post-processing module to subtract out the intercepted 
mass. This shows that how a model is applied can be just as important 
as the model design. Appropriate use of a model will help reduce 
uncertainties to a degree that allows decisions to be made with the 
necessary level of confidence.
---------------------------------------------------------------------------

    \25\ U.S. EPA. 2020. ``Review of Analyses in EPRI White Paper: 
Model Evaluation of Relative Performance of Alternative Liners.'' 
Prepared by the Office of Land and Emergency Management. February.
---------------------------------------------------------------------------

    To ensure that a model is applied appropriately, it is critical to 
understand all the assumptions built into that model. All models 
include some degree of simplification compared to the real world so 
that calculations are both feasible and manageable. More simplistic 
models may provide less precise results, but that does not mean these 
results are inadequate. Whether a model is appropriate is more often 
determined by how it is applied to support decision-making. The goal of 
modeling in the demonstration step is to provide confidence that peak 
groundwater concentrations that may result from releases throughout the 
active life of the impoundment will not exceed GWPS at the waste 
boundary. In this context, simplifying assumptions that will tend to 
overestimate the magnitude of contaminant release and transport can 
actually provide greater confidence in the conclusions of the 
demonstration.
    Therefore, based on the comments received, EPA is finalizing an 
additional requirement at Sec.  257.71(d)(1)(ii)(C)(1) that the models 
relied upon must be well-established and validated, with background 
documentation that can be made available for public review. Proprietary 
models that operate in a black box will not be considered appropriate 
for use in a demonstration.
b. Use of Groundwater Protection Standards
    EPA discussed in the proposal that as part of the demonstration, 
the owner or operator must demonstrate that the surface impoundment has 
not and will not result in groundwater concentrations above relevant 
GWPS at the waste boundary (health-based or background, whichever is 
higher). EPA stated that this is the standard used to trigger 
corrective action for lined surface impoundments and it is considered 
equally appropriate in this context.
    Several commenters raised concerns about the use of GWPS as the 
basis to determine that an impoundment is protective. One commenter 
alleged that facilities were allowed to set their own GWPS. Another 
commenter stated that EPA had not provided justification why the 
standard used to determine that lined surface impoundments must 
initiate corrective action is equally

[[Page 72526]]

appropriate to use in the approval of alternate liners.
    EPA believes that use of GWPS is appropriate and protective. GWPS 
are set as either specific regulatory standards identified in the CCR 
regulations or background groundwater concentrations, whichever is 
higher. Facilities are not granted discretion to establish alternate 
values. These standards are deemed to be protective and used in a 
number of regulatory programs within the Agency. EPA also considers 
them to be sufficient to demonstrate if the long-term performance of an 
alternate lined CCR impoundment can be protective because these 
standards align with those previously used to determine that composite-
lined units are protective.
    The 2014 Risk Assessment evaluated the risks associated with 
releases from CCR surface impoundments. As discussed previously, the 
only risks identified for clay-lined units in this risk assessment were 
the result of human ingestion of lithium in groundwater up to a mile 
away from the waste boundary. Lithium is one of the most mobile CCR 
constituents. If the engineered liner and/or naturally occurring soil 
of the alternate liner has an effective hydraulic conductivity 
sufficient to eliminate the risks associated with high-end lithium 
concentrations previously considered in the 2014 Risk Assessment, then 
there is confidence that the alternate liner will also prevent risks to 
both groundwater or surface water from the remaining constituents. 
Requiring the impoundment to meet the health-based GWPS for lithium at 
the waste boundary, where concentrations are highest, will only further 
limit the potential magnitude of releases from the alternate liner.
    Therefore, EPA is adopting a revised provision in the final rule 
that will better align the ALD requirements with the existing risk 
record and with the statutory standard in RCRA Sec.  4004(a). EPA is 
finalizing an additional requirement at Sec.  257.71(d)(1)(ii)(C)(2) 
that facilities must demonstrate that there is no reasonable 
probability that the peak groundwater concentrations that may result 
from releases that occur over the active life of the unit will exceed 
GWPS at the waste boundary.
c. Consideration of Background Groundwater Concentrations
    EPA did not explicitly discuss consideration of existing background 
groundwater concentrations in the proposal but noted that it is a key 
factor when establishing GWPS at a particular site. It follows that 
background is also a factor when determining if these standards have 
been exceeded. Naturally occurring background concentrations are 
typically much lower than promulgated GWPS, but have been found to 
exceed these standards in some places. Even when contributions from the 
impoundment are small, the addition of these releases to high existing 
background concentration may still trigger corrective action. Because a 
characterization of background is available on a site-specific basis 
and an ALD is required to show that the peak groundwater concentration 
that may result from releases over the active life of the impoundment 
will not exceed GWPS, existing background concentrations are a relevant 
consideration for all constituents. Consideration of existing 
background concentrations will only further limit the potential 
magnitude of any releases from the alternate liner.
    EPA is finalizing a new provision at Sec.  257.71(d)(1)(ii)(C)(3) 
that documentation of the model outputs must include the peak 
groundwater concentrations modeled for all Appendix IV constituents 
attributed to the impoundment both in isolation and in addition to 
background. This will provide an understanding of both the increase in 
concentration attributed to releases from the surface impoundment and 
the overall likelihood for an exceedance of GWPS.
d. Risk From Other Constituents
    Some commenters stated that units with ALDs should be forced to 
close after an SSI over background of any Appendix III constituent. 
Under this approach, any increase in concentrations distinguishable 
from background would trigger closure, regardless of the magnitude. 
Commenters expressed concern that reliance on Appendix IV constituents 
would not adequately protect against risks from the release of Appendix 
III constituents, such as boron and sulfate.
    EPA disagrees with these commenters. As discussed previously, EPA 
distinguishes between the situation prior to the time EPA has 
determined that the unit meets the requirements of the ALD and after 
EPA has determined that the unit meets the requirements. In the former 
case EPA must assume that the unit does not have the low hydraulic 
conductivity necessary to ensure the GWPS will never be exceeded; as a 
consequence, EPA is requiring the unit to remain in detection 
monitoring throughout the application process. By contrast, the record 
is very different with respect to a unit that has been approved for an 
ALD. In this case the site characteristics can support the additional 
time needed to determine the appropriate actions to address all the 
potential risks at that particular site. In addition, the Appendix III 
list is not intended to identify risk. These constituents and water 
quality parameters are intended to indicate that the overall 
groundwater chemistry has shifted, which may be the result of a release 
from the unit. Some additional constituents that were evaluated in the 
risk assessment, such as boron and fluoride, were selected because the 
higher mobility in the subsurface makes them ideal early indicators. 
EPA did not identify any risks for these constituents from clay-lined 
units. Therefore, a unit with an ALD that has been found to perform 
better than the modeled clay-lined units will also pose no concern for 
these constituents. Sulfate was not modeled in the risk assessment 
because EPA did not identify any health benchmarks derived in a manner 
consistent with the OLEM hierarchy for human health toxicity values or 
relevant ecological benchmarks. Nor did EPA receive any comments on the 
risk assessment identifying relevant benchmarks that the Agency had 
omitted. The review of the literature conducted in support of the 
advisory level identified some potential for laxative effects from 
elevated sulfate levels, though these effects were not observed for 
longer-term exposures as individuals appeared to adapt over time. EPA 
concluded that available data did not permit a full dose-response 
assessment for sulfate in water and ultimately set an advisory level 
lower than associated with short-term effects reported by any 
individual study.\26\ The World Health Organization subsequently 
reached a similar conclusion, stating that ``the existing data do not 
identify a level of sulfate in drinking-water that is likely to cause 
adverse human health effects.\27\'' Some organizations have chosen to 
compare this advisory level to monitoring well data reported by 
facilities to estimate risk.\28\ Even if this were an appropriate use 
of this advisory level, the report shows that sulfate levels above the 
advisory level occur concurrently with exceedances of GWPS and do not

[[Page 72527]]

outpace the magnitude of these exceedances. This is expected because 
several Appendix IV constituents can be associated with sulfate in the 
ash. There is no indication that the hypothetical risks from sulfate 
raised by the commenter would not be addressed by the requirements of 
this rule. Therefore, EPA maintains use of Appendix IV constituents as 
the basis for the alternate liner demonstration. However, as discussed 
in Unit IV.D.5.b of this preamble, detection of an SSI of Appendix III 
constituents will trigger additional measures designed to ensure that 
levels of Appendix IV constituents are never detected at SSLs. As 
discussed in Unit IV.D.5.b of this preamble, detection of an SSI of 
Appendix III parameters will trigger additional measures designed to 
ensure that an SSL of Appendix IV constituents do not occur.
---------------------------------------------------------------------------

    \26\ U.S. EPA. 2003. ``Drinking Water Advisory: Consumer 
Acceptability Advice and Health Effects Analysis on Sulfate.'' EPA 
822-R-03-007. Office of Water. February.
    \27\ World Health Organization. 2004. ``Sulfate in Drinking-
Water: Background Document for the Development of WHO Guidelines for 
Drinking-Water Quality.'' WHO/SDE/WSH/03.04/114.
    \28\ Environmental Integrity Project. 2019. ``Coal's Poisonous 
Legacy: Groundwater Contaminated by Coal Ash Across the U.S.''
---------------------------------------------------------------------------

D. Procedures for Approval and Denial of Alternate Liner Demonstration

    As mentioned previously, EPA proposed a two-step process first 
requiring the submittal of an application, and then, if the application 
is approved a demonstration. EPA also proposed regulations to govern 
the procedures for the review of and public comment on those documents. 
These elements of the proposal are discussed below.
1. Application Process
a. Deadline of Application Submission
    EPA proposed at Sec.  257.71(d)(2)(i) that the initial applications 
were due no later than thirty days after the effective date of the 
final rule. Industry commenters requested additional time to prepare 
and submit the application, as well as the ability to provide follow-up 
information beyond the deadline if EPA finds some aspect of the 
documentation to be inadequate. Commenters worried generally that a 
fixed deadline of 30 days would provide little time to prepare an 
application, and in particular that any time spent waiting for input 
from EPA would further limit the time remaining to make any necessary 
updates. Commenters stated that given the significance of this step, 
EPA must provide facilities with adequate time to assemble this 
critical preliminary information, which may require the assistance of 
third-party engineering firms. They further stated that facilities 
should not be rushed to prepare this information, which, if determined 
to be insufficient, will disqualify a facility from being able to seek 
an alternate liner demonstration and subject the unit to closure. EPA 
received comments requesting the ability to meet with EPA before 
submitting their application. Additionally, industry commenters were 
also concerned about the initial application deadline as it related to 
the proposed deadline of August 31, 2020 to cease receipt of waste, as 
well as the deadlines for submission of requests to obtain alternative 
compliance deadlines in 84 FR 65941 (December 2, 2019) (``Part A 
Proposed Rule'').
    EPA agrees with commenters that the proposed thirty-day deadline 
and the proposed date to cease receipt of waste could have made 
implementation difficult. In response to the comments, EPA is extending 
the timeframe available for facilities to submit the initial 
application. EPA believes that submittal by November 30, 2020, is 
appropriate for facilities to prepare and submit the application. This 
is the same date by which facilities will be required to submit 
requests for extensions pursuant to Sec.  257.103(f), and in the 
interest of simplifying the regulations it makes sense to coordinate 
the dates. This will provide sufficient time for facilities to become 
familiar with requirements of this rule and collect the information 
needed for the initial application. It is worth noting in this respect 
that EPA is not requiring the generation of new data or additional 
sampling to support the initial application. The additional time will 
also provide the Agency the ability to engage in a limited amount of 
discussion with a facility before the application submission deadline. 
Such discussions would need to occur before the deadline for final 
submission of the application. In regard to the deadline to cease 
receipt of waste, the Part A final rule established a deadline of April 
11, 2021, for those units that are closing pursuant to Sec.  
257.101(a)(1) or Sec.  257.101(b)(1)(i). This alleviates the concern 
that an owner or operator would not have sufficient time to submit an 
application before the deadline to cease receipt of waste.
    EPA also received comments in support of allowing the Participating 
State Director (i.e. the State Director of a State with an approved CCR 
State Permit Program in accordance with RCRA section 4005(d)) to review 
and approve alternate liner demonstrations. The commenters said states 
often have resources and expertise to evaluate applications and the 
associated technical documents necessary in order to approve alternate 
liner demonstrations. The Agency agrees that a Participating State 
Director should have the ability to review and approve an ALD, and 
therefore finalized provisions in Sec.  257.71(d) to allow that to 
occur.
    Therefore, EPA is finalizing at Sec.  257.71(d)(2)(i) that the 
owner or operator of the CCR surface impoundment must submit the 
application to EPA or the Participating State Director by November 30, 
2020. This date is consistent with the date in the Part A final rule to 
submit an alternative closure demonstration.
b. Application Review
    EPA proposed at Sec.  257.71(d)(2)(ii) that EPA or the 
Participating State Director will evaluate the application and may 
request additional information as necessary to complete its review. If 
the application was complete it would toll the facility's deadline to 
cease receipt of waste for that surface impoundment until issuance of a 
final decision on the surface impoundment's eligibility. However, EPA 
proposed that incomplete submissions would not toll the deadline. EPA 
proposed that within sixty days of receiving the application, EPA or 
the Participating State Director would notify the owner or operator of 
its determination on the eligibility of their surface impoundment, and 
finally, that the facility must post the determination to its publicly 
accessible CCR internet site. EPA stated in the proposed rule that if 
the Agency or Participating State Director determines the application 
is lacking necessary information or specificity, the facility may have 
an opportunity to resubmit with the required information, provided it 
was submitted before the deadline for all initial applications (i.e., 
30 days after the effective date of the final rule). However, no 
resubmissions could be accepted after this deadline.
    Many industry commenters requested clarification as to what 
information is required to constitute a complete application. Other 
commenters requested that EPA provide a separate certification process 
through PE certification, development of a checklist, or other means 
that could be used to confirm an application is ``complete'' before 
submittal. Commenters stated that a ``complete'' application consists 
of all the information necessary to trigger tolling of the facility's 
deadline to cease receipt of waste into that unit until a final 
decision on the unit's eligibility is issued. Commenters contrasted 
this with a ``sufficient'' application, which would allow a facility to 
proceed to the demonstration step. Because of the relatively short 
timeline provided to submit an application in the proposal, these 
commenters worried there would not be an opportunity to resubmit an

[[Page 72528]]

application found to be incomplete and the facility would not be 
allowed to toll the deadline. One commenter said that EPA should 
provide owners/operators with additional time beyond the original 
deadlines to make their resubmittals because an insufficient 
application submittal does not mean the liner itself is insufficient, 
which is the ultimate point for the alternate liner demonstrations.
    EPA is adopting procedures that largely mirror those adopted for 
requests submitted pursuant to Sec.  257.103(f). Upon receiving the 
application, EPA will evaluate the application to determine whether it 
is complete. EPA may request additional, clarifying information to 
complete its review and/or discuss the application with the facility. 
Consistent with the proposed rule, submissions that EPA determines to 
be incomplete will be rejected without further process, at which point 
any tolling of the facility's deadline will end. (EPA anticipates that 
the question of tolling for incomplete submissions should not generally 
arise, as the agency anticipates making these determinations before 
April 11, 2021). No commenter disagreed that this was appropriate. 
Incomplete submissions include both the situation in which the 
submission does not include all of the required material, and the 
situation in which EPA is unable to determine from the submission 
whether the facility or the unit meets the criteria for the 
application. EPA does not agree with the commenter that it would be 
appropriate to grant additional time to allow a facility to cure an 
incomplete application; the new deadline of November 30, 2020, provides 
more than a sufficient amount of time for the facility to submit a 
complete application. As discussed above, if an application was deemed 
incomplete, the owner or operator could attempt to cure the 
deficiencies and resubmit the application provided that it can do so 
before the November 30, 2020 deadline. If the application is deemed 
incomplete, the owner or operator may seek an alternative closure 
deadline pursuant to Sec.  257.103(f)(1) or (f)(2). For more 
information on this please see Unit III.D.3.
    EPA agrees that the timeframes are ambitious but continues to 
believe that they can be met. As discussed in more detail below, the 
Agency has limited the issues to be resolved during this process, and, 
as requested by commenters, has amended the proposed regulation to 
specify in detail the information needed for a submission to be 
considered complete. Consequently, EPA anticipates it will be able to 
make most decisions without further requests for information. Once the 
owner or operator submits the application to EPA for approval, the 
owner or operator must place a copy into the facility's operating 
record and on its publicly accessible CCR internet site. EPA will also 
post who has submitted an application on EPA's website.
    One commenter expressed concern that utilities' alternate liner 
applications would not be posted publicly prior to a proposed approval, 
and the beginning of the thirty-day comment period on the alternate 
liner demonstration would likely be the first time the vast majority of 
the public would have the opportunity to review many of the highly 
complex, technical documents that would form the basis of EPA's 
decision. In response to the comment about not providing an opportunity 
for public comment on the application and to be consistent with the 
process established in the Part A final rule, EPA is finalizing a 
requirement at Sec.  257.71(d)(2)(iii)(C) to provide for public comment 
on the application by granting a twenty day public comment period. 
After reviewing the submission, EPA will either post a determination 
that the submission is incomplete on EPA's website or a proposed 
decision to grant or to deny the request in the docket on 
www.regulations.gov for public notice and comment. EPA will also post 
the application on its website. EPA will allow for a 20-day public 
comment period. EPA will evaluate the comments received and amend its 
final decision as warranted. EPA will post all decisions on its 
website, in the relevant docket and notify the facility. EPA will make 
best efforts to complete the application review within sixty days of 
receiving the complete application.
    Some commenters raised the argument that because part 257 is self-
implementing and because certain regulatory provisions might be viewed 
as ambiguous, there could be differences in opinion on what constitutes 
compliance. These commenters felt that differences in interpretation 
should be discussed during EPA's review process and corrected as 
warranted as part of a facility's completion of its demonstration.
    EPA is establishing an expedited process to resolve requests for 
continued operation under Sec.  257.71(d); in order to meet these time 
frames EPA has limited the issues to be resolved in this proceeding. 
One of the primary issues to be resolved will be whether the facility 
is in compliance with the regulations. Although EPA does not agree that 
the regulations are ambiguous, EPA may be able to engage in a limited 
amount of discussion with a facility before the submission deadline. In 
addition, as explained previously, documentation that a facility 
remains in compliance with the requirements of part 257 subpart D 
provides critical support for a decision to allow continued operation 
of the unlined surface impoundment. This means that EPA must be able to 
affirmatively conclude that the facility meets this criterion prior to 
authorizing any continued operation of the unlined surface impoundment. 
As a consequence, any opportunity to correct the demonstration is 
limited to the period before the deadline for submission.
    Finally, note that any determinations made in evaluating the 
compliance aspects of submitted applications will be made solely for 
the purpose of determining whether to grant an initial application. In 
making these determinations the Agency generally expects to consider 
and rely on the information in a submission, information contained in 
submitted comments to a proposed decision, and any other information 
the Agency has at the time of the determination. These determinations 
may not be applicable or relevant in any other context. Should the 
facility's compliance status be considered outside of this context in 
the future, the Agency may reach a contrary conclusion based, for 
example, on new information or information that was not considered as 
part of this process.
    EPA is revising the regulatory text (now found at Sec.  
257.71(d)(2)(iii)) for the application review to more clearly reflect 
the circumstances under which a facility's deadline to cease receipt of 
waste will be tolled. Consistent with the recently promulgated 
regulations in Sec.  257.103, the regulations provide that the deadline 
to cease receipt of waste will be tolled by the submission of an 
application until EPA determines the application is incomplete or the 
application is denied. As previously discussed, because EPA anticipates 
making determinations on the initial application before the April 11, 
2021 deadline, issues of tolling should not arise for incomplete or 
denied applications. If EPA approves an application, the deadline to 
cease receipt of waste will continue to be tolled until EPA determines 
the demonstration is incomplete or issues the final disposition on the 
merits of the demonstration. The language in this section will still 
state that within sixty days of receiving a complete application, EPA 
or the Participating State Director will notify the owner or operator 
of its determination on the

[[Page 72529]]

eligibility of their surface impoundment. This section will also 
require that the facility must also post EPA's determination to its 
publicly accessible CCR internet site. Finally, this section states 
that the application will be available for public comment on EPA's 
docket for 20 days. EPA will evaluate comments as part of the review. 
EPA or the Participating State Director will post the decision on the 
application on their website and will add it to the docket.
c. Application Denial
    EPA proposed at Sec.  257.71(d)(2)(vi) that if EPA or the 
Participating State Director determines that the unit is not eligible 
for an ALD, the owner or operator must cease receipt of waste and 
initiate closure within six months of the denial or by the deadline in 
Sec.  257.101(a), whichever is later. If a facility needed to obtain 
alternative capacity, they could do so in accordance with the 
procedures in Sec.  257.103.
    Commenters requested clarification on how the timing of a denial 
would work with the deadlines applicable to units closing under Sec.  
257.101(a) and 257.101(b)(1)(i). EPA is revising its proposal to better 
account for coordination with the recently promulgated final deadlines 
and procedures associated with these surface impoundments. As 
previously discussed, EPA intends to issue a final decision within 
sixty days of submission of a complete application. Therefore, if the 
application was received on November 30, 2020, EPA would make best 
efforts to issue the denial by February 1, 2021 which is two months 
before the April 11, 2021 deadline by which these units are required to 
cease receipt of waste. Under the newly promulgated regulations the 
surface impoundment must either cease receipt of waste no later than 
April 11, 2021 or the owner or operator may apply for an alternative 
closure deadline in accordance with Sec.  257.103(f)(1) or (f)(2). 
Under the procedures associated with Sec.  257.103(f) facilities will 
have four months to submit an application. EPA is therefore granting 
facilities that need to submit an application to continue to operate 
the unit pursuant to Sec.  257.103 four months from the date of denial 
to submit their application. All other facilities must cease receipt of 
waste--either by the April 11, 2021 deadline (assuming EPA has issued 
its decision prior to the deadline) or by the revised deadline which 
will be included in the denial. This revised deadline will account for 
the amount of time EPA has taken to issue its decision. EPA has no 
basis to universally authorize the surface impoundment to continue 
operating for an additional six months in these circumstances. Those 
units that can close by the deadline must do so (e.g. because they have 
alternative capacity on site) or the facility must be treated the same 
as any other facility seeking an extension pursuant to Sec.  
257.103(f). Further discussion of the relationship of the timing of an 
application denial and the alternative closure standards is found in 
Unit III.D.3 below.
    Therefore, EPA is revising Sec.  257.71(d)(2)(vi) to remove the 
provision requiring the facility to initiate closure ``within six 
months of the denial.''
d. Multi-Unit Liner Demonstration
    The 2015 CCR Rule allowed monitoring networks for CCR units to be 
designed with consideration of multi-unit systems (i.e., multiple 
surface impoundments at one site) that share groundwater monitoring 
systems and other technical features. EPA made no reference to multi-
unit systems in the proposed rule. Multiple commenters requested 
clarification on how ALD requirements would apply to these multi-unit 
systems. Specifically, commenters inquired whether facilities with 
multiple units can submit a single application and demonstration that 
covers all the units, or if documentation for each individual unit must 
be submitted separately.
    Given that decisions about the design and implementation of these 
groundwater monitoring programs and such sites were made based on 
consideration of multiple units, EPA considers it to be reasonable that 
the ALD documentation could also include multiple units to reduce 
redundancy and ensure that each individual unit is discussed in the 
full context of the larger system. Further, given that these units are 
located in close proximity, the data generated for one is likely to be 
equally applicable to multiple units in the demonstration. For example, 
grouping data from wells around adjacent units will provide a more 
comprehensive picture of groundwater depth and flow around the wider 
facility. Therefore, EPA is amending the rule to make clear that a 
single application and demonstration may be submitted for multi-unit 
systems.
2. Demonstration Process
a. Deadline of Demonstration Submission
    EPA proposed at Sec.  257.71(d)(2)(i) that the facility would have 
one year from the date the application was due (i.e., 13 months from 
the effective date of the final rule) to submit their alternate liner 
demonstration if EPA approved their application. The proposal also 
stated that if the owner or operator cannot meet this deadline due to 
analytical limitations related to the measurement of hydraulic 
conductivity, the owner or operator must submit a request for an 
extension no later than 90 days prior to the deadline for submission of 
the demonstration, that includes a summary of the data collected to 
date that show the progress towards relevant test termination criteria 
for all samples responsible for the delay, along with an alternate 
timeline for completion that has been certified by the laboratory.
    One commenter stated that one year would not provide the amount of 
time needed to perform the robust analyses needed to provide greater 
certainty that the unit would pose no reasonable probability of adverse 
effects to human health or the environment. The commenter also stated 
that some of that one year would be spent waiting for a determination 
from EPA that the unit is eligible for an ALD. The commenter stated 
that this gave the facility only 10 months to prepare the ALD if they 
waited until their application was approved, and that would not be 
sufficient if they needed to install additional groundwater monitoring 
wells, validate fate and transport models, develop three-dimensional 
visualization to support conceptual site models, or establish 
background water quality to evaluate the potential effects for 
seasonality in the groundwater quality observations.
    EPA does not agree with the commenter. First, a facility should not 
wait for application approval to start their demonstration work. 
Second, EPA is not requiring a facility to install additional 
monitoring wells or further characterize background water quality to 
support the demonstration. Facilities were required to have installed 
an appropriate number of monitoring wells and to adequately 
characterize background water quality to evaluate the potential effects 
for seasonality years ago under part 257. EPA is not granting 
additional time as part of this process for facilities to come into 
compliance with existing requirements. Finally, while three-dimensional 
visualization may be useful for EPA's review, it is not a requirement. 
Therefore, the Agency is not revising the amount of time given to 
develop the demonstration package.
    EPA is finalizing Sec.  257.71(d)(2)(i) to require facilities to 
have one year from the date the application was due to submit their 
alternate liner demonstration. Therefore,

[[Page 72530]]

demonstrations are due no later than November 30, 2021. Once the owner 
or operator submits the demonstration to EPA for approval, the owner or 
operator must place a copy into the facility's operating record and on 
its publicly accessible CCR internet site.
    As mentioned above, EPA also proposed to allow extensions on the 
demonstration submittal deadline in the limited circumstance that it is 
not feasible for the lab to fully analyze the field samples by the 
demonstration deadline. EPA proposed that the request must be submitted 
no later than 90 days prior to the demonstration deadline. The proposal 
further stated that EPA or a Participating State Director would 
evaluate the information provided in the request and determine whether 
the duration of the requested extension is acceptable. EPA did not 
receive any comments that indicated the type of delay considered in the 
preamble was unreasonable or entirely avoidable. Some facilities 
requested additional information on the maximum duration of an 
extension, what information the facility should provide as part of the 
request, and whether extensions could be provided for any other 
reasons.
(i) Extension Due to Analytical Limitations for Chemical Equilibrium
    EPA discussed in the proposal that extensions would be allowed on 
the condition that analytical limitations prevent the necessary data 
from being collected by the demonstration deadline. EPA specifically 
pointed to the fact that tests for hydraulic conductivity may take 
upwards of 300 days to complete for extremely low conductivity soils. 
It is important that these tests be allowed to run to completion 
because long-term changes to soil structure, such as flocculation of 
clay particles, can substantially alter the conductivity of the soil.
    One commenter raised concerns that hydraulic conductivity tests for 
low permeability soils may take longer than the timeframe allotted for 
the demonstration but made no reference to the deadline extension 
discussed in the preamble. Another commenter requested clarification on 
the duration of an extension and what information should be provided as 
part of the request.
    As acknowledged in the proposal, EPA understands that the test 
methods for hydraulic conductivity may take a considerable amount of 
time. EPA continues to believe it is critical that these tests are 
allowed to run to completion to ensure that effects of leachate 
chemistry on the liner integrity are identified. Therefore, EPA will 
allow a one-time extension on the deadline for submittal of the 
demonstration for analytical limitations associated with completing the 
hydraulic conductivity test. The duration of the extension will be 
determined solely by the time projected by the lab to achieve 
termination criteria for chemical equilibrium. These metrics will 
progress along either a linear or asymptotic curve as the composition 
of the effluent approaches that of the influent. Thus, it is 
reasonable, based on these curves and the rate of flow for the lab to 
estimate how long it will take to approach and maintain conditions for 
test termination for the necessary duration. EPA expects facilities 
that receive this extension will use this additional time to prepare 
all other necessary documentation so that, once the data is available, 
it will be a relatively straightforward task to run the model and 
document the results. Once the owner or operator receives the data, 
they will have 45 days beyond the timeframe certified by the laboratory 
for the facility to submit the completed demonstration.
    In response to comments, EPA is finalizing amendments to clarify 
that, as part of the extension request, facilities must provide (1) a 
brief timeline of fieldwork to confirm that samples were collected 
expeditiously, (2) a chain of custody documenting when samples were 
sent to the laboratory, (3) written certification from the lab 
identifying how long it is projected for the necessary termination 
criteria to be met, and (4) documentation of the progression towards 
all termination metrics to date.
(ii) Other Analytical Limitations
    One commenter requested clarification on what other types of 
analytical limitations EPA would be considered eligible for extension. 
However, the commenter did not provide a specific example of another 
type of analytical limitation that might warrant a similar extension.
    It is possible that chemical interactions between the soil and 
leachate may cause the measured hydraulic conductivity to shift 
abruptly and substantially due to resulting changes in the soil 
structure. This shift may be substantial enough that it will take 
longer for the hydraulic conductivity to stabilize than it will for the 
chemistry of the system to reach equilibrium. This scenario may occur 
regardless of whether an extension has been provided to allow system 
chemistry to reach equilibrium. Yet, unlike chemical equilibrium 
between the influent and effluent, there is no predefined endpoint for 
hydraulic conductivity. As a result, there are no reasonable means to 
predict how much longer it will take for this parameter to fully 
stabilize. However, it is expected that the bulk of any changes to soil 
structure and hydraulic conductivity will have occurred by the time 
that the chemistry of the system has achieved equilibrium. This is 
because the primary driver of these changes, the exchange of ions 
between the soil and the leachate, is mostly complete. For this reason, 
EPA believes that the magnitude of any changes to hydraulic 
conductivity recorded by the time chemical equilibrium has been 
established can provide a reasonable upper bound on any future changes. 
Thus, rather than provide an unspecifiable amount of additional time to 
allow the hydraulic conductivity to fully stabilize, EPA concludes it 
is preferable in this case that the owner or operator complete the 
demonstration within the existing deadline with the available data. Use 
of appropriate bounds of uncertainty based on the magnitude of changes 
to hydraulic conductivity measured to date can ensure that long-term 
contaminant transport is not underestimated.
    Therefore, EPA is finalizing amendments to the proposal to clarify 
that, if the measured hydraulic conductivity has not stabilized to 
within acceptable tolerance limits by the time the termination criteria 
for solution chemistry are met, the owner or operator must submit a 
preliminary demonstration within the existing deadline (with or without 
the one-time extension for analytical limitations). In this preliminary 
demonstration, the owner or operator must justify how the bounds of 
uncertainty applied to the available measurements of hydraulic 
conductivity ensure that the final value is not underestimated. The 
preliminary demonstration will be subject to all of the same process, 
notification and posting requirements of a final demonstration. EPA 
will review the preliminary demonstration to determine if it is 
complete and will propose to deny or to tentatively approve the 
demonstration. Once the final laboratory results are available, the 
owner or operator must submit a final demonstration that incorporates 
the finalized hydraulic conductivity data to confirm that the model 
results in the preliminary demonstration are accurate. Until the time 
that EPA takes final action on this final demonstration, the surface 
impoundment must stay in detection monitoring to remain eligible for an 
ALD. If EPA tentatively approved the preliminary demonstration, EPA 
will then take action on the newly

[[Page 72531]]

submitted final demonstration using the same procedures that apply to 
the initial determination. The public will have an opportunity to 
comment only on the new information presented in the complete final 
demonstration or in EPA's proposed decision on the revised 
demonstration.
(iii) Extension Request Deadline
    EPA proposed that facilities must submit a request for an extension 
no later than 90 days before the deadline for submission of the 
demonstration. One commenter requested additional time to submit the 
request, stating that unforeseen issues might arise late in the 
demonstration process that necessitate an extension. The commenter did 
not elaborate on the types of delays that may occur so late in the 
process. In order to complete the demonstration on time, EPA expects 
facilities to collect the necessary field data expeditiously and long 
before the extension request deadline. The facility should be aware of 
and be able to plan for any complications associated with sample 
collection. Once data have been collected from the field and analyzed, 
the remaining modeling and documentation can be completed in the office 
where the risk of unavoidable delay is minimal. Indeed, much of the 
necessary documentation can be compiled concurrently with sample 
collection and analysis. EPA is maintaining the submission deadline for 
extension requests that the owner or operator of the CCR surface 
impoundment must submit the extension request no later than September 
1, 2021. The owner or operator must also post this extension request on 
their publicly accessible CCR internet site.
b. Demonstration Review
    EPA proposed at Sec.  257.71(d)(2)(iii) that EPA or the 
Participating State Director will evaluate the demonstration package 
and may request additional information as necessary to complete its 
review. Submission of a complete demonstration package will continue to 
toll the facility's deadline to cease receipt of waste into that unit 
until issuance of a final decision under Sec.  257.71(d)(2)(v). 
Incomplete submissions will cease tolling the facility's deadline. EPA 
also proposed at Sec.  257.71(d)(2)(iv) that EPA or the Participating 
State Director will propose a decision on the demonstration and post 
that decision on EPA or Participating State Director's website for a 
30-day public comment period. Finally, EPA proposed at Sec.  
257.71(d)(2)(v) that after consideration of the comments, EPA or the 
Participating State Director will make a final decision within four 
months of receiving the complete alternate liner demonstration and that 
if no substantive comments were received the decision would become 
automatically effective 5 days from the close of the comment. The 
facility must also post EPA's determination on its ALD to its publicly 
accessible CCR internet site.
    Commenters pointed out that there appeared to be an unintended gap 
in tolling. The proposed regulatory text indicated that the deadline to 
cease receipt of waste would not be tolled during the period between 
approval of the initial application and the time the alternate liner 
demonstration package was submitted. That was not the Agency's intent. 
EPA intended that the deadline would be tolled during the entire time 
between an approved application and the final determination on the ALD. 
Accordingly, the regulatory text has been amended to make this clear.
    EPA also received comments that the 30-day public comment period 
was too short to allow for sufficient opportunity for members of the 
public to review and comment on such highly complex, technical 
documents. EPA acknowledges that the public comment period is short but 
disagrees that it is too short to be meaningful. EPA is requiring 
facilities to post all submissions on their publicly accessible CCR 
internet site at the same time they submit them to EPA. The public can 
start their review at the same time as EPA and begin to gather 
information and prepare their comments. For similar reasons, EPA also 
disagrees that a 30-day comment period violates either the 
Administrative Procedures Act (APA) or RCRA 7004(b). This process is 
not a rulemaking, but an informal adjudication. Such adjudications do 
not typically include an opportunity for public comment and therefore 
the provision of a 30-day comment period meets the mandate in RCRA 
Sec.  7004(b) to promote public participation. Moreover, the APA 
imposes neither a requirement to provide an opportunity for public 
comment nor any minimum time for a comment period for such procedures. 
Finally, EPA notes that the same commenters requesting longer comment 
periods have also raised concern that the process grants facilities too 
much additional time to continue operating. EPA is also interested in 
not granting undue amounts of additional time for facilities to 
continue operating and is expediting all aspects of this process, 
including the comment period. After reviewing the submission, EPA will 
post a proposed decision to grant or to deny the demonstration in the 
docket on www.regulations.gov for public notice and comment. EPA will 
also post the demonstration on its website.
    One commenter stated that the regulations do not give the reviewing 
agency a deadline for approving or disapproving a submitted 
demonstration, so that such a demonstration can remain pending 
indefinitely. The Agency disagrees with that comment and is finalizing 
as proposed Sec.  257.71(d)(2)(v) which states that EPA will evaluate 
the comments received and amend its decision as warranted within four 
months. EPA will post all final decisions on EPA's website and in the 
appropriate docket. The facility must post, along with a copy of its 
demonstration, the Agency's final decision on the facility's publicly 
accessible CCR internet site.
    Finally, EPA is not finalizing the automatic five-day effective 
date for demonstrations with no substantive comments since this 
approach would be too difficult to implement.
c. Demonstration Denial
    EPA proposed at Sec.  257.71(d)(2)(vi) that if EPA or the 
Participating State Director determines that the unit's alternate liner 
does not meet the standard for approval, the owner or operator must 
cease receipt of waste and initiate closure within six months of the 
denial. If a facility needs to obtain alternative capacity, they may do 
so in accordance with the procedures in Sec.  257.103.
    Commenters were primarily concerned about the ability to pursue a 
capacity extension under Sec.  257.103 if their ALD was denied.
    If an ALD is denied and the facility lacks capacity, the owner or 
operator may apply for one of the site-specific alternative deadlines 
Sec.  257.103(f)(1) or (f)(2) as described below. As discussed in that 
section the time frames for applying for those alternatives will be 
governed by Sec.  257.103(f) rather than the six months contemplated by 
the proposal. By contrast, if the owner or operator chooses to not 
apply for Sec.  257.103(f)(1) or (f)(2), for example, if they already 
have alternative capacity to manage their waste on site, then the 
surface impoundment must cease receipt of waste and initiate closure by 
the date specified in EPA's decision (which will be the date EPA 
determines that such actions are technically feasible).

[[Page 72532]]

3. Relationship to Sec.  257.103(f)(1) and (f)(2) Alternative Closure 
Requirements
    In the proposal, EPA stated that should a facility pursuing an ALD 
not have alternative capacity, the owner or operator must continue to 
actively pursue avenues of obtaining alternative capacity during the 
time they are pursuing the ALD. Commenters were concerned that this 
would put the owner or operator in the position of devoting resources 
to two parallel paths to seek an extension under both Sec.  257.71(d) 
and under either Sec.  257.103(f)(1) or (f)(2). The Agency understands 
that the facility will be required to expend resources on two parallel 
tracks, but continues to believe that owners or operators that are 
pursuing an ALD who lack alternative capacity in which to manage their 
wastes must actively work to attain that capacity during the ALD 
process. As discussed in more detail below, facilities will not be able 
to obtain more than the maximum time allowed under Sec.  257.103(f); in 
order to meet these deadlines, facilities will need to be pursuing 
alternative capacity well before EPA would render a decision on their 
ALD. To do otherwise would create incentives for facilities to apply 
for an ALD as a means of obtaining additional time under Sec.  
257.103(f)(1) or (f)(2). Any owners or operators that are preparing to 
submit an ALD and whose facilities lack alternative capacity should 
therefore also be preparing to submit a demonstration of lack of 
capacity under either Sec.  257.103(f)(1) or (f)(2) in the event their 
application is denied.
    The current deadline for all facilities who lack capacity and wish 
to apply for the Sec.  257.103(f)(1) or (f)(2) alternative closure 
requirements is November 30, 2020. That provides the owner or operator 
approximately 4 months from the signature date of the Part A final rule 
to submit the demonstration. Accordingly, if an application is rejected 
or an ALD is denied the owner or operator will be given four months to 
apply for either Sec.  257.103(f)(1) or (f)(2). The facility's deadline 
to cease receipt of waste will be tolled during these four months to 
allow the owner or operator to develop the Sec.  257.103(f)(1) or 
(f)(2) demonstration. Thereafter, consistent with the procedures 
adopted in Sec.  257.103, the deadline to cease receipt of waste will 
continue to be tolled until the Agency determines whether the 
submission is incomplete or reaches a final decision. As stated 
earlier, the Part A final rule requires owners and operators to submit 
demonstrations under the alternative closure provisions of Sec.  
257.103(f)(1) or (f)(2) by November 30, 2020. To accommodate facilities 
whose application or alternative liner demonstration under Sec.  
257.71(d) is denied and who intend to submit a demonstration under the 
alternative closure provisions, the Agency is revising Sec.  
257.103(f)(3)(i)(A) and (C) to allow such demonstrations to be 
submitted after the deadline of November 30, 2020. Specifically, EPA is 
revising Sec.  257.103(f)(3)(i)(A) and (C) by adding the clause 
``Except as provided by Sec.  257.71(d)(2)(iii)(E) and (viii),'' to 
each paragraph.
    A facility may not be granted more time than the maximum that is 
provided in Sec.  257.103(f)(1) or (f)(2), even if the owner or 
operator is applying for the alternate closure requirements after they 
are denied an ALD. Specifically, a unit that qualifies for alternate 
closure dates under Sec.  257.103(f)(1) would still be required to 
cease receipt of waste no later than October 15, 2023. An eligible 
unlined surface impoundment granted a capacity extension must cease 
receiving CCR and/or non-CCR wastestreams no later than October 15, 
2024. In order to continue to operate until October 15, 2024, the owner 
or operator must demonstrate that the unit meets the definition of an 
eligible unlined CCR surface impoundment. Units applying for an ALD 
that ultimately are granted alternate closure dates under Sec.  
257.103(f)(2) would need to cease operation of their coal fired boiler 
and complete closure of the surface impoundment no later than October 
17, 2023 if they are 40 acres or smaller and by October 17, 2028 if 
they are larger than 40 acres.
4. Recertification
    EPA discussed in the proposal that the approved demonstration will 
be effective for the remaining active life of the unit since the 
demonstration must show that the engineered liner and/or naturally 
occurring soil is sufficient to prevent adverse effects from the 
surface impoundment.
    Several facilities and industry groups affirmed that a one-time 
demonstration is appropriate. Several other commenters argued that 
units should be required to periodically recertify the results of the 
ALD. One of these commenters cited to several studies to argue that 
onsite hydrogeologic conditions can shift suddenly and affect the 
performance of the liner. These commenters pointed to shifting land use 
and climate change as phenomena that could impact liner performance. 
The land uses envisioned by the commenter include increased agriculture 
or urban development. However, the commenters provided no direct 
explanation how these changes were expected to impact liner 
performance.
    A study cited by this commenter noted that the climate change would 
primarily impact surface water, but that there could also be impacts to 
the quantity and quality of groundwater.\29\ The most likely way in 
which this could impact liner performance would be a decrease in the 
depth to groundwater. However, the long-term trends considered by these 
and other studies are often projected out many decades into the future 
and are variable across the country. Portions of the country are 
projected to see a decrease in precipitation, while others are 
projected to see an increase through more intense storms, which may or 
may not translate to increased groundwater recharge. Similarly, the 
land uses cited would only further deplete groundwater through 
increased extraction for agriculture or increased runoff from more 
impervious surfaces. Regardless, the 2014 Risk Assessment found that 
variations in the water table height did not substantially shift high-
end risks, particularly for the most mobile constituents. Therefore, 
there is no indication that shifts in the groundwater table would alter 
the conclusion whether continued operation of a surface impoundment in 
the near term is protective. In addition, depth to groundwater is a 
parameter that is routinely measured during all phases of groundwater 
monitoring and so it will be apparent without recertification if 
groundwater levels are rising. Changes to the background quality of 
groundwater that has no direct contact with the unit would have no 
effect on whether the unit remains protective. As a result, it is not 
apparent from the comments provided what would be further achieved by 
requiring facilities to periodically recertify the characterization of 
local hydrogeology. Therefore, EPA made no amendments to the 
requirements of the rule in response to this comment.
---------------------------------------------------------------------------

    \29\ Green, T.R., M. Taniguchi, H. Kooi, J.J. Gurdak, D.M. 
Allen, K.M. Hiscock, H. Treidel, and A. Aureli. 2011. ``Beneath the 
Surface of Global Change: Impacts of Climate Change on 
Groundwater.'' Journal of Hydrology. 405:532-560.
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5. Loss of Authorization
    EPA proposed at Sec.  257.71(d)(2)(vii)(A) that authorization of an 
ALD could be rescinded at any time if the facility fails to maintain 
the performance standard or any other requirement of this rule. To 
identify the potential for a future exceedance of GWPS, the Agency 
proposed that facilities that trigger assessment monitoring would need 
to

[[Page 72533]]

conduct intra-well analyses on each downgradient well to identify any 
trends of increasing concentrations and this information would be 
included as part of subsequent groundwater monitoring reports. The 
proposal further stated that if there is evidence that the unit may 
exceed GWPS before source control measures were put in place (e.g., 
dewatering, impermeable cap, clean closure), then the alternative liner 
authorization would be reconsidered.
    EPA also proposed at Sec.  257.71(d)(2)(vii)(B) that the onus would 
remain on the facility at all times to demonstrate that the unit meets 
the conditions for authorization of the ALD. The proposal further 
stated that EPA or the Participating State Director could, without 
further notice or process, deny or revoke the owner or operator's 
authorization if these conditions for qualification were no longer 
being met.
    EPA received a number of comments on the proposed loss of 
authorization provisions. Some industry groups and facilities requested 
confirmation that an option is available to demonstrate whether 
increased groundwater concentrations are attributed to a source 
unrelated to the unit before authorization would be revoked. One 
facility claimed that it was inappropriate to rely on groundwater 
monitoring at all to determine compliance. Several environmental groups 
stated that use of GWPS to determine ongoing compliance is not 
protective, while several industry groups commented that use of trend 
analysis was not a reliable way to determine compliance.
a. Use of Groundwater Monitoring To Determine Ongoing Compliance
    The proposed rule stated at Sec.  257.71(d)(2)(vii)(A) that if at 
any time assessment monitoring pursuant to Sec.  257.95 is triggered 
for the unit, the facility must conduct intra-well analyses on each 
well as part of subsequent groundwater monitoring reports to identify 
any trends of increasing concentrations. The proposal further explained 
that if trend analysis predicts there will be an exceedance of GWPS for 
any constituent, EPA or the Participating State Director would 
reconsider the authorization and may revoke it if source control 
measures could not be put in place while the unit continues to operate.
    In response to that provision, one commenter stated it was 
inappropriate to rely on groundwater monitoring to determine whether a 
unit continued to meet the standards of the ALD because groundwater 
monitoring does not provide direct information about whether the 
conditions of the liner or site soils have changed. Instead, this 
commenter argued the rule should allow for an examination of changes to 
the liner itself, or changes in the site soils, hydrology or other site 
conditions evaluated in the demonstration.
    EPA disagrees that groundwater monitoring is an inappropriate 
method by which to establish whether a unit remains in compliance with 
this rule. Groundwater monitoring provides direct evidence of the 
impoundment's impact on groundwater quality. Whether these impacts are 
a result of a material change to the liner is immaterial to the fact 
that those impacts have occurred. In addition, the commenter provided 
no indication of what types of examinations were envisioned, how these 
examinations would be triggered, how these examinations could be used 
to prove a unit remains protective, and how this all would proceed 
faster than groundwater monitoring. To address all of these issues, EPA 
proposed the use of trend analysis to identify the potential for harm 
before it would occur so that it can be addressed. Therefore, EPA 
maintains the requirement to base continued authorization of an ALD on 
the results of groundwater monitoring.
b. Trend Analysis
    EPA proposed at Sec.  257.71(d)(2)(vii)(A) that units with an 
approved ALD that have entered into assessment monitoring (i.e., SSI of 
Appendix III) must conduct additional intra-well analysis to identify 
any increasing trends of Appendix IV constituents in groundwater. A 
positive trend can show that contaminant levels have gotten worse 
compared to earlier measurements from the same well. Understanding the 
nature of the trend, including the rate of increase per unit of time, 
allows estimation of how rapidly concentration levels are increasing. 
If the identified trendline is steep enough to result in an exceedance 
of GWPS within the timeframe required to complete closure of the unit, 
the facility would have to begin implementation of source control 
measures at that time.
    The final rule adopts a provision that largely tracks the proposal. 
The final rule requires that if a unit with an approved ALD enters into 
assessment monitoring, the facility must, in addition to their regular 
groundwater monitoring, conduct additional intra-well analysis to 
identify any statistically significant trend of increasing 
concentrations of appendix IV constituents in groundwater. If the 
identified trendline is steep enough that it would result in an 
exceedance of a GWPS at any point during the active life of the unit, 
the facility must close the unit.\30\ This final provision represents a 
change only for those units that have a geosynthetic liner; the 
proposal specified that units with only natural soil liners would be 
required to close at this point, as the agency was aware of no other 
effective option for source control. The Agency is expanding this 
requirement to units with geosynthetic liners in response to comments 
stating that the Agency lacked data to demonstrate that these liners 
can be effectively repaired.
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    \30\ The comparison of a projected concentration to groundwater 
standards is not a statistical test of significance because, without 
measurements of future groundwater concentrations, it is predicated 
on the assumption that the current trend will persist unchanged. 
Nevertheless, the fact that the impoundment has entered into 
assessment monitoring, there is a statistically significant trend of 
increasing concentration, and the current magnitude of that trend 
has the potential to result in a future exceedance of GWPS is 
considered sufficient evidence that a release has occurred and there 
is a reasonable probability that continued operation of the 
impoundment could adversely affect groundwater.
---------------------------------------------------------------------------

    Trend analysis will require collection of multiple samples to 
define whether and to what extent concentrations are changing over 
time. As discussed in the following Unit, EPA is requiring that the 
necessary samples be collected over the course of the following year; 
however, there is minimal risk that an impoundment able to obtain an 
ALD and that has no prior history of releases might trigger corrective 
action so soon after entering into assessment monitoring. As discussed 
previously, an SSI of Appendix III constituents is not an indication 
that adverse effects have occurred or will occur. An SSI only shows 
that there has been some increase in Appendix III constituents 
discernable from background, regardless of the magnitude. Multiple 
constituents on Appendix III were included on this list for their 
mobility in the environment and so provide the best early indicators 
that a release has occurred. As a result, at the time that an SSI is 
first identified, it is possible that there will not have been any 
associated increase in most Appendix IV constituents. This will be 
confirmed by the first sample collected within the initial 90-day 
window in accordance with the existing requirements in Sec.  257.95(b). 
Any further increase in concentrations of Appendix IV constituents is 
expected to be gradual based on the documented low conductivity of the 
engineered liner and/or naturally occuring soil provided in the ALD. 
The fact that many of these alternately lined units will have operated 
for decades without ever leaving detection monitoring provides 
additional evidence that any releases

[[Page 72534]]

identified in the future are indeed slow moving or small in magnitude. 
It is possible for an impoundment to remain in assessment monitoring 
for the remainder of its operational life without ever exceeding GWPS. 
As demonstrated for composite-lined units in the 2014 Risk Assessment, 
releases can occur from even the most well-designed units and these 
units can remain protective for the duration of their active life.
    EPA received a number of specific comments on the application of 
trend analysis. These comments and the revisions made to the proposed 
rule in response are discussed in the following Units of preamble.
(i) Identification of Trends
    Commenters claimed that use of trend analysis is inconsistent and 
inferior to the statistical methods already required and do not meet 
the performance standards of Sec.  257.93(g). Commenters stated that 
the proposal provided no guidance on how to identify trends and that 
the criteria used by EPA to determine that units were noncompliant 
would be subjective.
    Trend analysis serves a distinct purpose from the other statistical 
methods. Methods detailed in Sec.  257.93(f) for use in assessment 
monitoring are intended to identify whether groundwater concentrations 
have exceeded GWPS, while trend analysis, as used in this context, is 
intended to identify whether GWPS could be exceeded in the future. 
Trend analysis does not substitute for monitoring data and statistical 
evaluations already required by the rule. Trend tests are robust 
statistical methods and have previously been applied by the Agency both 
to provide evidence of plume migration and the need to expand the 
monitoring well network. EPA has previously developed guidance and 
tools to aid in applying trend analysis.\31\ \32\ Statistical 
identification of a positive trend involves testing the estimated slope 
coefficient from the regression trend line. Identification of a pattern 
of increase within the sampling record provides a reliable method to 
determine that concentrations have risen more than expected by chance 
alone. Once the trend is calculated, confidence limits around the trend 
line should be calculated to account for variability within the 
dataset. The upper 95th percentile confidence limit on the trend line 
must be used to ensure potential increases have not been 
underestimated. Use of the upper percentile is considered appropriate 
here because the goal is to prevent the impoundment entering into 
corrective action in the future. Waiting for the corresponding lower 
confidence limit to exceed GWPS to take action would provide greater 
certainty that an exceedance will occur by a certain time, but it would 
also make it far more likely that an exceedance could occur before 
then.
---------------------------------------------------------------------------

    \31\ U.S. EPA. 2009. ``Statistical Analysis of Groundwater 
Monitoring Data at RCRA Facilities Unified Guidance.'' EPA 530-R-09-
007. Prepared by the Office of Solid Waste and Emergency Response. 
Washington, DC. March.
    \32\ U.S. EPA. 2018. ``Groundwater Statistics Tool User's 
Guide.'' Prepared by the Office of Solid Waste and Emergency 
Response. Washington, DC. September.
---------------------------------------------------------------------------

    The final rule also includes a minimum sampling frequency to ensure 
that the number of samples collected is consistent with the data 
requirements in Sec.  257.93(e). Four independent samples is generally 
considered the minimum number necessary to conduct meaningful 
statistical analysis on a trend. The first of these samples must be 
collected within 90 days of triggering assessment monitoring in 
accordance with Sec.  257.95(b). The remaining three must be collected 
on a quarterly basis within a year of triggering assessment monitoring. 
After establishing this baseline from the initial sampling events, the 
subsequent monitoring frequency will be established in accordance with 
Sec.  257.95(d). The trend analysis must be updated after each sampling 
event.
    There will always be some degree of uncertainty associated with 
extrapolation of measured data into the future, with uncertainty 
increasing the further the trend is projected into the future. There is 
potential that reliance on trends can overestimate the potential of 
future exceedances. For example, it is possible that linearly 
increasing concentrations may eventually plateau at some level below 
GWPS. However, asymptotic conditions occur gradually and during that 
time concentrations continue to increase, albeit at a slower rate. 
Therefore, a decline in the slope of the trend does not itself ensure 
that GWPS will not eventually be exceeded. Additionally, there is no 
way to guarantee based on existing monitoring data that any plateau in 
current concentrations will be sustained in perpetuity. The timeframe 
required for trendline projection is commensurate with the uncertainty 
associated with closure, which is directly related to the size and 
complexity of the unit. Although full closure may take the full time 
projected, the initial steps of ceasing placement of new ash and 
dewatering the unit will have the greatest relative impact on releases 
by eliminating the primary mechanisms driving infiltration to the 
subsurface.
    Therefore, EPA is adopting a provision at Sec.  
257.71(d)(2)(vii)(A) to ensure that the number of samples available 
will provide sufficient information to support decisions. Except as 
provided for in Sec.  257.95(c), the owner or operator must collect a 
minimum of four independent samples from each well (background and 
downgradient) within one year of triggering assessment monitoring and 
analyze each sample for all Appendix IV constituents.\33\ After the 
initial sampling period, monitoring may revert to the previously 
established frequency.
---------------------------------------------------------------------------

    \33\ U.S. EPA. 2018. ``Groundwater Statistics Tool User's 
Guide.'' Prepared by the Office of Solid Waste and Emergency 
Response. Washington, DC. September.
---------------------------------------------------------------------------

    EPA is also finalizing a requirement at Sec.  
257.71(d)(2)(vii)(A)(1) to clarify that the owner or operator of the 
CCR unit must apply an appropriate statistical test to identify trends 
within the monitoring data. For normal distributions of data, linear 
regression will be used to identify the presence and magnitude of any 
trends. For non-normal distributions of data, the Mann-Kendall test 
will be used to identify the presence of a trend and the Theil-Sen 
trend line will be used to determine the associated magnitude. The test 
used shall comply, as appropriate, with the performance standards in 
Sec.  257.93(g). If a trend is identified, the facility will use the 
upper 95th percentile confidence limit on the trend line to determine 
if GWPS could be exceeded in the future. The facility will project this 
trend line into the future for a duration set to the maximum number of 
years allowed for closure of the surface impoundment pursuant to Sec.  
257.102.
    The owner or operator must submit to EPA a report of the results of 
each sampling event, as well as the initial trend analysis and they 
must include all data relied upon by the facility to support the 
analysis. The reports and the final trend analysis must be posted to 
the facility's publicly accessible CCR internet site and submitted to 
EPA within 14 days of completion. EPA will publish a proposed decision 
on the trend analysis on www.regulations.gov for a 30-day comment 
period. After consideration of the comments, EPA will issue its 
decision. If the trend analysis shows the potential for a future 
exceedance of a groundwater protection standard the CCR surface 
impoundment must cease receipt of waste pursuant to the withdrawal 
notice. Furthermore, if at any time the unit exceeds any GWPS, the 
authorization will be withdrawn.

[[Page 72535]]

(ii) Alternative Source Demonstrations Under Sec.  257.94(e)
    Under an approved alternative liner demonstration, EPA proposed 
that if groundwater monitoring detects a statistically significant 
increase of any Appendix III constituent, the facility would need to 
complete an alternative source demonstration pursuant to Sec.  
257.94(e) or initiate assessment monitoring pursuant to Sec.  257.95. 
85 FR 12462 (March 3, 2020). In response to the proposal, commenters 
noted that the proposed regulatory text did not include a specific 
provision allowing for alternative source demonstrations to be made 
under Sec.  257.94(e) prior to proceeding to assessment monitoring. 
These commenters requested the final rule include such regulatory text. 
These commenters further requested that the final rule allow facilities 
the opportunity to complete an alternative source demonstration when an 
Appendix IV constituent is detected at statistically significant levels 
above a GWPS pursuant to Sec.  257.95(g) prior to initiating corrective 
action activities.
    The current regulations provide facilities the opportunity under 
each phase of the groundwater monitoring program to demonstrate that a 
source other than the CCR unit caused the increase in groundwater 
concentrations for a constituent or that the increase resulted from an 
error in sampling, analysis, statistical evaluation, or natural 
variation in groundwater quality. Sec. Sec.  257.94(e) and 257.95(g). 
The final rule does not eliminate the opportunity for an owner or 
operator to make an alternative source demonstration for an Appendix 
III constituent pursuant to Sec.  257.94(e), but the Agency has amended 
it slightly for units with an ALD. Similar to the provision at 
257.95(g), the unit with an ALD may pursue an alternate source 
demonstration simultaneously while conducting the trend analysis. Given 
that it will take close to a year to complete a trend analysis, EPA 
considers that waiting an additional 90 days to commence the trend 
analysis is not warranted in this circumstance. As a consequence, the 
Agency agrees with commenters that the rule should include a specific 
provision allowing for alternative source demonstrations to be made 
under Sec.  257.94(e). This regulatory text is codified in Sec.  
257.71(d)(2)(ix)(A)(1) in the final rule.
    EPA disagrees with commenters that the rule should allow for 
alternative source demonstrations in the assessment monitoring program 
under Sec.  257.95(g) when an Appendix IV constituent is detected at a 
statistically significant level. First, because the purpose of the 
requirement to close based on the trend analysis is to ensure that no 
Appendix IV constituent is detected at a statistically significant 
level, the provision at Sec.  257.95(g) should never be triggered while 
the unit is operating under an alternative liner demonstration. Nor is 
it likely that an alternative source of contamination will be present 
that had not been discovered previously as a consequence of the 
detection of a statistically significant increase of one or more 
Appendix III constituents. Finally, while the Agency does agree that 
the risk of drawing incorrect conclusions about unit performance based 
on the presence of an error is equally applicable to the trend analysis 
conducted during assessment monitoring, EPA believes it is more 
appropriate for the facility to address such errors in the trends 
analysis sampling results report required under Sec.  
257.71(d)(2)(ix)(B). Therefore, the final rule does not allow owners 
and operators to make use of the alternative source demonstration 
provisions under Sec.  257.95(g) while operating under the alternative 
liner demonstration provisions.
    If an owner or operator pursuing an alternative liner demonstration 
makes a successful alternative source demonstration for an Appendix III 
constituent pursuant to Sec.  257.94(e), the final rule requires the 
owner or operator to submit the alternative source demonstration to EPA 
for review and approval. The Agency is requiring review and approval of 
alternative source demonstrations because a successful demonstration 
under Sec.  257.94(e) allows a CCR unit to continue with the detection 
monitoring program instead of progressing to an assessment monitoring 
program. EPA is finalizing this requirement at Sec.  
257.71(d)(2)(ix)(A)(4).
    The owner or operator must post the alternative source 
demonstration to the facility's publicly accessible CCR internet site 
and submit it to EPA for review and approval within 14 days of 
completing the demonstration. EPA will publish a proposed decision on 
the alternative source demonstration on www.regulations.gov for a 20-
day comment period. After consideration of the comments, EPA will issue 
its decision. If the alternative source demonstration is approved by 
EPA, the owner operator may return to detection monitoring under Sec.  
257.94 and cease conducting the trend analysis. If the alternative 
source demonstration is denied by EPA, the owner or operator must 
either complete the trend analysis or cease receipt of waste and 
initiate closure of the unit, as well as initiating an assessment 
monitoring program as provided by Sec.  257.94(e). See Sec.  
257.71(d)(2)(ix)(A)(5).
(iii) Source Control
    In the proposed rule EPA explained that if there was evidence that 
the groundwater concentrations may exceed the groundwater protection 
standard for any Appendix IV constituent within the operational life of 
the CCR unit, EPA or the Participating State Director would reevaluate 
the authorization and may revoke it if source control measures could 
not be put in place while the unit continues to operate. 85 FR 12462, 
12477 (March 3, 2019). EPA further explained that for units without a 
geomembrane liner the only source control that would be effective was 
the unit to cease receipt of waste and initiate closure.
    Several commenters stated that the proposed rule contemplates 
repair of clay-lined impoundments as part of source control. These 
commenters further explained that the available record does not support 
the conclusion that a clay-lined surface impoundment can be repaired 
successfully. These commenters also raised the concern that proposal 
procedures were deficient in that facilities were not required to 
provide evidence of liner repairability in order to continue to 
operate. Commenters also stated that the proposed source control 
provisions would cause harmful delays in closure of unlined 
impoundments by providing additional time for a facility to continue 
operating while attempting to put source controls in place after 
detection of a groundwater protection standard exceedance. EPA received 
no comments that contradicted the agency's conclusion that closure is 
the only method of source control that would be effective for units 
with a natural soil-based liner.
    After reviewing the record again, EPA agrees that the agency failed 
to identify any data to demonstrate that the source of a leak from an 
impoundment that receives an ALD can be identified and repaired. 
Therefore, the final rule treats units with a geomembrane the same as 
impoundments that rely on only a natural soil-based liner and requires 
them to close upon a determination that a GWPS will be exceeded during 
the active life of the unit.

[[Page 72536]]

IV. Corrections to Sec. Sec.  257.102 and 257.103

A. Correction to the Alternative Final Cover System Requirements

    EPA proposed to revise the alternative final cover system 
requirements under Sec.  257.102(d)(3)(ii) to correct a typographical 
error (85 FR 12468, March 3, 2020). In the introductory text to Sec.  
257.102(d)(3)(ii), the regulations provide that the ``owner or operator 
may select an alternative final cover system design, provided the 
alternative final cover system is designed and constructed to meet the 
criteria in paragraphs (f)(3)(ii)(A) through (D) . . .'' EPA explained 
in the proposal that the reference to paragraphs (f)(3)(ii)(A) through 
(D) is an incorrect cross-reference approval and that the correct 
cross-reference should be to the criteria in paragraphs (d)(3)(ii)(A) 
through (C). The Agency received no comments in response to this 
proposed change. In this action, EPA is finalizing the proposal to 
revise the introductory text of Sec.  257.102(d)(3)(ii).

B. Revisions to the Alternative Closure Requirements

    EPA recently promulgated amendments to the alternative closure 
requirements under Sec.  257.103 that provide closure options in 
situations where an owner or operator is closing a CCR unit but has no 
alternative disposal capacity or is permanently closing the coal-fired 
boiler in the foreseeable future (85 FR 53516, August 28, 2020)(``Part 
A final rule''). Since publication of the Part A final rule, the Agency 
has identified a typographical error in the regulatory text. This error 
is being corrected in this final rule and are described below.
1. Correction to Sec.  257.103(f)(1)(vi)
    Section 257.103(f)(1)(vi) establishes maximum time frames that 
wastes may be managed in a CCR surface impoundment while operating 
pursuant to the alternative closure provisions under Sec.  
257.103(f)(1). The regulatory text under Sec.  257.103(f)(1)(vi) 
provides that ``All CCR surface impoundments covered by this section 
must cease receiving waste by the deadlines specified . . .'' (emphasis 
added). As discussed in the Part A final rule, the maximum time frames 
provided for in Sec.  257.103(f)(1)(vi) only apply to impoundments 
operating under Sec.  257.103(f)(1); however, the use of the term 
``section'' in this regulatory text could be interpreted incorrectly to 
apply also to other provisions under Sec.  257.103, such as the 
alternative closure provisions under Sec.  257.103(f)(2). Therefore, 
EPA is replacing the word ``section'' in the introductory text of Sec.  
257.103(f)(1)(vi) with ``paragraph (f)(1)'' to reflect the intent of 
the provision.

V. Rationale for 30-Day Effective Date

    The effective date of this rule is 30 days after publication in the 
Federal Register. With some exceptions (see 5 U.S.C. 553(a),(d)), the 
Administrative Procedure Act (APA) provides that publication of a 
substantive rule shall be made not less than 30 days before its 
effective date and that this provision applies in the absence of a 
specific statutory provision establishing an effective date. See 5 
U.S.C. 553(d) and 559. EPA has determined there is no specific 
provision of RCRA addressing the effective date of regulations that 
would apply here, and thus the APA's 30-day effective date applies.
    EPA has previously interpreted section 4004(c) of RCRA to generally 
establish a six-month effective date for rules issued under subtitle D. 
See 80 FR 37988, 37990 (July 2, 2015). After further consideration, EPA 
interprets section 4004(c) to establish an effective date solely for 
the regulations that were required to be promulgated under subsection 
(a). Section 4004(c) is silent as to subsequent revisions to those 
regulations; EPA therefore believes section 4004(c) is ambiguous.
    Section 4004(c) states that the prohibition in subsection (b) shall 
take effect six months after promulgation of regulations under 
subsection (a). Subsection (a), in turn provides that ``[n]ot later 
than one year after October 21, 1976 . . . [EPA] shall promulgate 
regulations containing criteria for determining which facilities shall 
be classified as sanitary landfills and which shall be classified as 
open dumps within the meaning of this chapter.'' As noted, section 
4004(c) is silent as to revisions to those regulations.
    In response to Congress's mandate in section 4004(a), EPA 
promulgated regulations on September 13, 1979. 44 FR 53438. EPA 
interprets section 4004(c) to establish an effective date applicable 
only to that action, and not to future regulations the Agency might 
issue under this section. In the absence of a specific statutory 
provision establishing an effective date for this rule, APA section 
553(d) applies.
    EPA considers that its interpretation is reasonable because there 
is no indication in RCRA or its legislative history that Congress 
intended for the agency to have less discretion under RCRA subtitle D 
than it would have under the APA to establish a suitable effective date 
for subsequent rules issued under section 4004(c). Consistent with 
EPA's interpretation of the express language of section 4004, EPA 
interprets statements in the legislative history, explaining that 
section 4004(c) provides that the effective date is to be 6 months 
after the date of promulgation of regulations, as referring to the 
initial set of regulations required by Congress to be promulgated not 
later than 1 year after October 21, 1976. These statements do not 
mandate a 6 month effective date for every regulatory action that EPA 
takes under this section. This rule contains specific, targeted 
revisions to the 2015 rule and the legislative history regarding 
section 4004 speaks only to these initial 1976 mandated regulations.
    This reading allows the Agency to establish an effective date 
appropriate for the nature of the regulation promulgated, which is what 
EPA believes Congress intended. EPA further considers that the minimum 
30-day effective date under the APA is reasonable in this circumstance 
where none of the provisions being finalized require an extended period 
of time for regulated entities to comply.

VI. Effect of This Final Rule on States With Approved CCR Programs

    This final rule has impacts on states with an approved program. As 
of this final rule, EPA has granted approvals to the states of Oklahoma 
and Georgia.
    Oklahoma and Georgia were each granted approval for Sec.  257.71, 
and their regulations continue to operate without change in lieu of the 
federal program. In essence this means that the revisions promulgated 
in this rule making will not take effect in either of these states 
until such time as Oklahoma or Georgia revises the program to adopt 
them.
    EPA has determined that this rule is not more stringent than the 
current regulations in 40 CFR Subpart D. As a consequence, neither 
state is required to adopt these provisions in order to maintain 
program approval. See, RCRA section 4005(d)(1)(D)(i)(II).
    The process for approving Oklahoma or Georgia's modifications is 
the same as for the initial program approval: EPA will propose to 
approve or deny the program modification and hold a public hearing 
during the comment period. EPA will then issue the final program 
determination within 180 days of determining that the state's 
submission is complete.

VII. The Projected Economic Impacts of This Action

A. Introduction

    EPA estimated the costs and benefits of this action in a Regulatory 
Impact

[[Page 72537]]

Analysis (RIA) which is available in the docket for this action. The 
RIA estimates that the net annualized impact of this proposed 
regulatory action over a 100-year period of analysis will be annual 
cost savings of approximately $ 4.0 million to $ 8.0 million when 
discounting at 7% and approximately $ 2.2 million to $ 4.5 million when 
discounting at 3%. This action is not considered an economically 
significant action under Executive Order 12866.

B. Affected Universe

    The rule potentially affects coal fired electric utility plants 
(assigned to the utility sector North American Industry Classification 
System (NAICS) code 221112) that dispose of their waste onsite in 
surface impoundments. The universe consists of approximately 523 
surface impoundments at 229 facilities.

C. Costs, Cost Savings, and Benefits of the Final Rule

    The Alternative Liner Demonstration finalized in this rule results 
in paperwork costs associated with submitting an application for 
demonstration and, if approved, the required demonstration. Provision 
One also results in cost savings associated with delays in closure of 
units (i.e., time value of money savings). Overall, the RIA estimates 
that the time value of money cost savings will be greater than the 
paperwork costs, making this a net cost savings rule of approximately 
$4.0 million to $8.0 million per year when discounting at 7% and 
approximately $2.2. million to $4.5 million per year when discounting 
at 3%.
    The rule is not anticipated to result in impacts to benefits. A 
qualitative discussion of benefits is available in Chapter 3 of the 
RIA, which can be found in the docket for this rulemaking.

VIII. Executive Orders

    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

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

    This is a significant regulatory action that was submitted to the 
Office of Management and Budget (OMB) for review because it raises 
novel legal or policy issues. Any changes made in response to OMB 
recommendations have been documented in the docket. EPA prepared an 
analysis of the potential costs and benefits associated with this 
action. This analysis is available in the docket and is summarized in 
Unit VII of this preamble.

B. Executive Order 13771: Reducing Regulation and Controlling 
Regulatory Costs

    This action is considered an Executive Order 13771 deregulatory 
action. Details on the estimated cost savings of this final rule can be 
found in EPA's analysis of the potential costs and benefits associated 
with this action.

C. Paperwork Reduction Act (PRA)

    The information collection activities in this proposed rule have 
been submitted for approval to the Office of Management and Budget 
(OMB) under the PRA. The Information Collection Request (ICR) document 
that the EPA prepared has been assigned EPA ICR number 2609.02. You can 
find a copy of the ICR in the docket for this rule, and it is briefly 
summarized here.
    The information to be collected as a part of this rule includes 
demonstrations that must be made to EPA by owners and operators of 
units that seek to obtain an alternate liner demonstration under Sec.  
257.71(d). These demonstrations will show that the unit in question 
meets the necessary criteria to receive the extension.
    Respondents/affected entities: Coal-fired electric utility plants 
that will be affected by the rule.
    Respondent's obligation to respond: The recordkeeping, 
notification, and posting are mandatory as part of the minimum national 
criteria being promulgated under Sections 1008, 4004, and 4005(a) of 
RCRA.
    Estimated number of respondents: 7.
    Frequency of response: The frequency of response varies.
    Total estimated burden: EPA estimates the total annual burden to 
respondents to be an increase in burden of approximately 2,179 hours 
from the currently approved burden. Burden is defined at 5 CFR 
1320.3(b).
    Total estimated cost: $900,000 (per year), includes $0 annualized 
capital costs and $785,000 annualized operation & maintenance costs.
    An agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for the 
EPA's regulations in 40 CFR are listed in 40 CFR part 9.

D. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. In 
making this determination, the impact of concern is any significant 
adverse economic impact on small entities. An agency may certify that a 
rule will not have a significant economic impact on a substantial 
number of small entities if the rule relieves regulatory burden, has no 
net burden or otherwise has a positive economic effect on the small 
entities subject to the rule. This action is expected to result in net 
cost savings of approximately $4.0 million to $8.0 million per year 
when discounting at 7% and $2.2 million to $4.5 million per year when 
discounting at 3%. These cost savings will accrue to all regulated 
entities. We have therefore concluded that this action will relieve 
regulatory burden for all directly regulated small entities.

E. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate of $100 million 
or more as described in UMRA, 2 U.S.C. 1531-1538, and does not 
significantly or uniquely affect small governments. This action imposes 
no enforceable duty on any state, local or tribal governments or the 
private sector.

F. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

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

    This action does not have tribal implications as specified in 
Executive Order 13175. This action does not impose substantial direct 
compliance costs or otherwise have a substantial direct effect on one 
or more Indian tribes, to the best of EPA's knowledge. Neither will it 
have substantial direct effects on the relationship between the federal 
government and Indian tribes, or on the distribution of power and 
responsibilities between the Federal government and Indian tribes. 
Thus, Executive Order 13175 does not apply to this action.

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

    This action is not subject to Executive Order 13045 because it is 
not economically significant as defined in Executive Order 12866, and 
because the EPA does not believe the environmental health risks or 
safety risks addressed by

[[Page 72538]]

this action present a disproportionate risk to children. This action's 
health and risk assessments are contained in the document titled 
``Human and Ecological Risk Assessment of Coal Combustion Residuals,'' 
which is available in the docket for the final rule as docket item EPA-
HQ-RCRA-2009-0640-11993.
    As ordered by E.O. 13045 Section 1-101(a), for the ``Final Rule: 
Hazardous and Solid Waste Management System; Disposal of Coal 
Combustion Residuals from Electric Utilities'' published April 17, 2015 
(80 FR 21302), EPA identified and assessed environmental health risks 
and safety risks that may disproportionately affect children in the 
revised risk assessment. The results of the screening assessment found 
that risks fell below the criteria when wetting and run-on/runoff 
controls required by the rule are considered. Under the full 
probabilistic analysis, composite liners required by the rule for new 
waste management units showed the ability to reduce the 90th percentile 
child cancer and non-cancer risks for the groundwater to drinking water 
pathway to well below EPA's criteria. Additionally, the groundwater 
monitoring and corrective action required by the rule reduced risks 
from current waste management units. This action does not adversely 
affect these requirements and EPA believes that this rule will be 
protective of children's health.

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

    This action is not a ``significant energy action'' because it is 
not likely to have a significant adverse effect on the supply, 
distribution or use of energy. For the 2015 CCR rule, EPA analyzed the 
potential impact on electricity prices relative to the ``in excess of 
one percent'' threshold. Using the Integrated Planning Model (IPM), EPA 
concluded that the 2015 CCR Rule may increase the weighted average 
nationwide wholesale price of electricity between 0.18 percent and 0.19 
percent in the years 2020 and 2030, respectively. As the final rule 
represents a cost savings rule relative to the 2015 CCR rule, this 
analysis concludes that any potential impact on wholesale electricity 
prices will be lower than the potential impact estimated of the 2015 
CCR rule; therefore, this final rule is not expected to meet the 
criteria of a ``significant adverse effect'' on the electricity markets 
as defined by Executive Order 13211.

J. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not involve technical standards.

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

    The EPA believes that this action does not have disproportionately 
high and adverse human health or environmental effects on minority 
populations, low-income populations and/or indigenous peoples, as 
specified in Executive Order 12898 (59 FR 7629, February 16, 1994). The 
documentation for this decision is contained in EPA's Regulatory Impact 
Analysis (RIA) for the CCR rule which is available in the docket for 
the 2015 CCR final rule as docket item EPA-HQ-RCRA-2009-0640-12034.
    The EPA's risk assessment did not separately evaluate either 
minority or low-income populations. However, to evaluate the 
demographic characteristics of communities that may be affected by the 
CCR rule, the RIA compares the demographic characteristics of 
populations surrounding coal-fired electric utility plants with broader 
population data for two geographic areas: (1) One-mile radius from CCR 
management units (i.e., landfills and impoundments) likely to be 
affected by groundwater releases from both landfills and impoundments; 
and (2) watershed catchment areas downstream of surface impoundments 
that receive surface water run-off and releases from CCR impoundments 
and are at risk of being contaminated from CCR impoundment discharges 
(e.g., unintentional overflows, structural failures, and intentional 
periodic discharges).
    For the population as a whole 24.8 percent belong to a minority 
group and 11.3 percent falls below the Federal Poverty Level. For the 
population living within one mile of plants with surface impoundments 
16.1 percent belong to a minority group and 13.2 percent live below the 
Federal Poverty Level. These minority and low-income populations are 
not disproportionately high compared to the general population. The 
percentage of minority residents of the entire population living within 
the catchment areas downstream of surface impoundments is 
disproportionately high relative to the general population i.e., 28.7 
percent, versus 24.8 percent for the national population. Also, the 
percentage of the population within the catchment areas of surface 
impoundments that is below the Federal Poverty Level is 
disproportionately high compared with the general population, i.e., 
18.6 percent versus 11.3 percent nationally.
    Comparing the population percentages of minority and low income 
residents within one mile of landfills to those percentages in the 
general population, EPA found that minority and low-income residents 
make up a smaller percentage of the populations near landfills than 
they do in the general population, i.e., minorities comprised 16.6 
percent of the population near landfills versus 24.8 percent nationwide 
and low-income residents comprised 8.6 percent of the population near 
landfills versus 11.3 percent nationwide. In summary, although 
populations within the catchment areas of plants with surface 
impoundments appear to have disproportionately high percentages of 
minority and low-income residents relative to the nationwide average, 
populations surrounding plants with landfills do not. Because landfills 
are less likely than impoundments to experience surface water run-off 
and releases, catchment areas were not considered for landfills.
    The CCR rule is risk-reducing with reductions in risk occurring 
largely within the surface water catchment zones around, and 
groundwater beneath, coal-fired electric utility plants. Since the CCR 
rule is risk-reducing and this action does not add to risks, this 
action will not result in new disproportionate risks to minority or 
low-income populations.

L. Congressional Review Act (CRA)

    This action is subject to the CRA, and EPA will submit a rule 
report to each House of the Congress and to the Comptroller General of 
the United States. This action is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

List of Subjects in 40 CFR Part 257

    Environmental protection, Beneficial use, Coal combustion products, 
Coal combustion residuals, Coal combustion waste, Disposal, Hazardous 
waste, Landfill, Surface impoundment.

Andrew Wheeler,
Administrator.

    For the reasons set out in the preamble, EPA amends 40 CFR part 257 
as follows:

PART 257--CRITERIA FOR CLASSIFICATION OF SOLID WASTE DISPOSAL 
FACILITIES AND PRACTICES

0
1. The authority citation for part 257 continues to read as follows:

[[Page 72539]]

    Authority: 42 U.S.C. 6907(a)(3), 6912(a)(1), 6944, 6945(a) and 
(d); 33 U.S.C. 1345(d) and (e).

0
2. Amend Sec.  257.71 by adding paragraph (d) to read as follows:

Sec.  257.71  Liner design criteria for existing CCR surface 
impoundments.

* * * * *
    (d) Alternate Liner Demonstration. An owner or operator of a CCR 
surface impoundment constructed without a composite liner or alternate 
composite liner, as defined in Sec.  257.70(b) or (c), may submit an 
Alternate Liner Demonstration to the Administrator or the Participating 
State Director to demonstrate that based on the construction of the 
unit and surrounding site conditions, that there is no reasonable 
probability that continued operation of the surface impoundment will 
result in adverse effects to human health or the environment. The 
application and demonstration must be submitted to the Administrator or 
the Participating State Director no later than the relevant deadline in 
paragraph (d)(2) of this section. The Administrator or the 
Participating State Director will act on the submissions in accordance 
with the procedures in paragraph (d)(2) of this section.
    (1) Application and alternative liner demonstration submission 
requirements. To obtain approval under this paragraph (d), the owner or 
operator of the CCR surface impoundment must submit all of the 
following:
    (i) Application. The owner or operator of the CCR surface 
impoundment must submit a letter to the Administrator or the 
Participating State Director, announcing their intention to submit a 
demonstration under paragraph (d)(1)(ii) of this section. The 
application must include the location of the facility and identify the 
specific CCR surface impoundment for which the demonstration will be 
made. The letter must include all of the following:
    (A) A certification signed by the owner or operator that the CCR 
unit is in full compliance with this subpart except for Sec.  
257.71(a)(1);
    (B) Documentation supporting the certification required under 
paragraph (d)(1)(i)(A) of this section that includes all the following:
    (1) Documentation that the groundwater monitoring network meets all 
the requirements of Sec.  257.91. This must include documentation that 
the existing network of groundwater monitoring wells is sufficient to 
ensure detection of any groundwater contamination resulting from the 
impoundment, based on direction of flow, well location, screening depth 
and other relevant factors. At a minimum, the documentation must 
include all of the following:
    (i) Map(s) of groundwater monitoring well locations in relation to 
the CCR unit(s) that depict the elevation of the potentiometric surface 
and the direction(s) of groundwater flow across the site;
    (ii) Well construction diagrams and drilling logs for all 
groundwater monitoring wells;
    (iii) Maps that characterize the direction of groundwater flow 
accounting for temporal variations; and
    (iv) Any other data and analyses the owner or operator of the CCR 
surface impoundment relied upon when determining the design and 
location of the groundwater monitoring network.
    (2) Documentation that the CCR surface impoundment remains in 
detection monitoring pursuant to Sec.  257.94 as a precondition for 
submitting an application. This includes documentation that the 
groundwater monitoring program meets the requirements of Sec. Sec.  
257.93 and 257.94. Such documentation includes data of constituent 
concentrations, summarized in table format, at each groundwater 
monitoring well monitored during each sampling event, and documentation 
of the most recent statistical tests conducted, analyses of the tests, 
and the rationale for the methods used in these comparisons. As part of 
this rationale, the owner or operator of the CCR surface impoundment 
must provide all data and analyses relied upon to comply with each of 
the requirements of this part;
    (3) Documentation that the unit meets all the location restrictions 
under Sec. Sec.  257.60 through 257.64;
    (4) The most recent structural stability assessment required at 
Sec.  257.73(d); and
    (5) The most recent safety factor assessment required at Sec.  
257.73(e).
    (C) Documentation of the design specifications for any engineered 
liner components, as well as all data and analyses the owner or 
operator of the CCR surface impoundment relied on when determining that 
the materials are suitable for use and that the construction of the 
liner is of good quality and in-line with proven and accepted 
engineering practices.
    (D) Facilities with CCR surface impoundments located on properties 
adjacent to a water body must demonstrate that there is no reasonable 
probability that a complete and direct transport pathway (i.e., not 
mediated by groundwater) can exist between the impoundment and any 
nearby water body. If the potential for such a pathway is identified, 
then the unit would not be eligible to submit a demonstration. If 
ongoing releases are identified, the owner or operator of the CCR unit 
must address these releases in accordance with Sec.  257.96(a); and
    (E) Upon submission of the application and any supplemental 
materials submitted in support of the application to the Administrator 
or the Participating State Director, the owner or operator must place 
the complete application in the facility's operating record as required 
by Sec.  257.105(f)(14).
    (ii) Alternate Liner Demonstration Package. The completed alternate 
liner demonstration package must be certified by a qualified 
professional engineer. The package must present evidence to demonstrate 
that, based on the construction of the unit and surrounding site 
conditions, there is no reasonable probability that operation of the 
surface impoundment will result in concentrations of constituents 
listed in appendix IV to this part in the uppermost aquifer at levels 
above a groundwater protection standard. For each line of evidence, as 
well as any other data and assumptions incorporated into the 
demonstration, the owner or operator of the CCR surface impoundment 
must include documentation on how the data were collected and why these 
data and assumptions adequately reflect potential contaminant transport 
from that specific impoundment. The alternate liner demonstration at a 
minimum must contain all of the following lines of evidence:
    (A) Characterization of site hydrogeology. A characterization of 
the variability of site-specific soil and hydrogeology surrounding the 
surface impoundment that will control the rate and direction of 
contaminant transport from the impoundment. The owner or operator must 
provide all of the following as part of this line of evidence:
    (1) Measurements of the hydraulic conductivity in the uppermost 
aquifer from all monitoring wells associated with the impoundment(s) 
and discussion of the methods used to obtain these measurements;
    (2) Measurements of the variability in subsurface soil 
characteristics collected from around the perimeter of the CCR surface 
impoundment to identify regions of substantially higher conductivity;
    (3) Documentation that all sampling methods used are in line with 
recognized and generally accepted practices that can provide data at a 
spatial resolution necessary to adequately characterize the variability

[[Page 72540]]

of subsurface conditions that will control contaminant transport;
    (4) Explanation of how the specific number and location of samples 
collected are sufficient to capture subsurface variability if:
    (i) Samples are advanced to a depth less than the top of the 
groundwater table or 20 feet beneath the bottom of the nearest water 
body, whichever is greater, and/or
    (ii) Samples are spaced further apart than 200 feet around the 
impoundment perimeter;
    (5) A narrative description of site geological history; and
    (6) Conceptual site models with cross-sectional depictions of the 
site environmental sequence stratigraphy that include, at a minimum:
    (i) The relative location of the impoundment with depth of ponded 
water noted;
    (ii) Monitoring wells with screening depth noted;
    (iii) Depiction of the location of other samples used in the 
development of the model;
    (iv) The upper and lower limits of the uppermost aquifer across the 
site;
    (v) The upper and lower limits of the depth to groundwater measured 
from monitoring wells if the uppermost aquifer is confined; and
    (vi) Both the location and geometry of any nearby points of 
groundwater discharge or recharge (e.g., surface water bodies) with 
potential to influence groundwater depth and flow measured around the 
unit.
    (B) Potential for infiltration. A characterization of the potential 
for infiltration through any soil-based liner components and/or 
naturally occurring soil that control release and transport of 
leachate. All samples collected in the field for measurement of 
saturated hydraulic conductivity must be sent to a certified laboratory 
for analysis under controlled conditions and analyzed using recognized 
and generally accepted methodology. Facilities must document how the 
selected method is designed to simulate on-site conditions. The owner 
or operator must also provide documentation of the following as part of 
this line of evidence:
    (1) The location, number, depth, and spacing of samples relied upon 
is supported by the data collected in paragraph (d)(1)(ii)(A) of this 
section and is sufficient to capture the variability of saturated 
hydraulic conductivity for the soil-based liner components and/or 
naturally occurring soil;
    (2) The liquid used to pre-hydrate the samples and measure long-
term hydraulic conductivity reflects the pH and major ion composition 
of the CCR surface impoundment porewater;
    (3) That samples intended to represent the hydraulic conductivity 
of naturally occurring soils (i.e., not mechanically compacted) are 
handled in a manner that will ensure the macrostructure of the soil is 
not disturbed during collection, transport, or analysis; and
    (4) Any test for hydraulic conductivity relied upon includes, in 
addition to other relevant termination criteria specified by the 
method, criteria that equilibrium has been achieved between the inflow 
and outflow, within acceptable tolerance limits, for both electrical 
conductivity and pH.
    (C) Mathematical model to estimate the potential for releases. 
Owners or operators must incorporate the data collected for paragraphs 
(d)(1)(ii)(A) and (d)(1)(ii)(B) of this section into a mathematical 
model to calculate the potential groundwater concentrations that may 
result in downgradient wells as a result of the impoundment. Facilities 
must also, where available, incorporate the national-scale data on 
constituent concentrations and behavior provided by the existing risk 
record. Application of the model must account for the full range of 
site current and potential future conditions at and around the site to 
ensure that high-end groundwater concentrations have been effectively 
characterized. All of the data and assumptions incorporated into the 
model must be documented and justified.
    (1) The models relied upon in this paragraph (d)(1)(ii)(C) must be 
well-established and validated, with documentation that can be made 
available for public review.
    (2) The owner or operator must use the models to demonstrate that, 
for each constituent in appendix IV of this part, there is no 
reasonable probability that the peak groundwater concentration that may 
result from releases to groundwater from the CCR surface impoundment 
throughout its active life will exceed the groundwater protection 
standard at the waste boundary.
    (3) The demonstration must include the peak groundwater 
concentrations modeled for all constituents in appendix IV of this part 
attributed both to the impoundment in isolation and in addition to 
background.
    (D) Upon submission of the alternative liner demonstration to the 
Administrator or the Participating State Director, the owner or 
operator must place the complete demonstration in the facility's 
operating record as required by Sec.  257.105(f)(15).
    (2) Procedures for adjudicating requests--(i) Deadline for 
application submission. The owner or operator must submit the 
application under paragraph (d)(1)(i) of this section to EPA or the 
Participating State Director for approval no later than November 30, 
2020.
    (ii) Deadline for demonstration submission. If the application is 
approved the owner or operator must submit the demonstration required 
under paragraph (d)(1)(ii) of this section to EPA or the Participating 
State Director for approval no later than November 30, 2021.
    (A) Extension due to analytical limitations. If the owner or 
operator cannot meet the demonstration deadline due to analytical 
limitations related to the measurement of hydraulic conductivity, the 
owner or operator must submit a request for an extension no later than 
September 1, 2021 that includes a summary of the data that have been 
analyzed to date for the samples responsible for the delay and an 
alternate timeline for completion that has been certified by the 
laboratory. The extension request must include all of the following:
    (1) A timeline of fieldwork to confirm that samples were collected 
expeditiously;
    (2) A chain of custody documenting when samples were sent to the 
laboratory;
    (3) Written certification from the lab identifying how long it is 
projected for the tests to reach the relevant termination criteria 
related to solution chemistry, and
    (4) Documentation of the progression towards all test termination 
metrics to date.
    (B) Length of extension. If the extension is granted, the owner or 
operator will have 45 days beyond the timeframe certified by the 
laboratory to submit the completed demonstration.
    (C) Extension due to analytical limitations for chemical 
equilibrium. If the measured hydraulic conductivity has not stabilized 
to within acceptable tolerance limits by the time the termination 
criteria for solution chemistry are met, the owner or operator must 
submit a preliminary demonstration no later than September 1, 2021 
(with or without the one-time extension for analytical limitations).
    (1) In this preliminary demonstration, the owner or operator must 
submit a justification of how the bounds of uncertainty applied to the 
available measurements of hydraulic conductivity ensure that the final 
value is not underestimated.
    (2) EPA will review the preliminary demonstration to determine if 
it is

[[Page 72541]]

complete and, if so, will propose to deny or to tentatively approve the 
demonstration. The proposed determination will be posted in the docket 
on www.regulations.gov and will be available for public comment for 30 
days. After consideration of the comments, EPA will issue its decision 
on the application within four months of receiving a complete 
preliminary demonstration.
    (3) Once the final laboratory results are available, the owner or 
operator must submit a final demonstration that updates only the 
finalized hydraulic conductivity data to confirm that the model results 
in the preliminary demonstration are accurate.
    (4) Until the time that EPA approves this final demonstration, the 
surface impoundment must remain in detection monitoring or the 
demonstration will be denied.
    (5) If EPA tentatively approved the preliminary demonstration, EPA 
will then take action on the newly submitted final demonstration using 
the procedures in paragraphs (d)(2)(iv) through (vi) of this section.
    (6) The public will have 30 days to comment but may comment only on 
the new information presented in the complete final demonstration or in 
EPA's tentative decision on the newly submitted demonstration.
    (D) Upon submission of a request for an extension to the deadline 
for the demonstration due to analytical limitations pursuant to 
paragraph (d)(2)(ii)(A) of this section, the owner or operator must 
place the alternative liner demonstration extension request in the 
facility's operating record as required by Sec.  257.105(f)(16).
    (E) Upon submission of a preliminary demonstration pursuant to 
paragraph (d)(2)(ii)(C) of this section, the owner or operator must 
place the preliminary demonstration in the facility's operating record 
as required by Sec.  257.105(f)(17).
    (iii) Application review--(A) EPA will evaluate the application and 
may request additional information not required as part of the 
application as necessary to complete its review. Submission of a 
complete application will toll the facility's deadline to cease receipt 
of waste until issuance of a final decision under paragraph 
(d)(2)(iii)(C) of this section. Incomplete submissions will not toll 
the facility's deadline and will be rejected without further process.
    (B) If the application is determined to be incomplete, EPA will 
notify the facility. The owner or operator must place the notification 
of an incomplete application in the facility's operating record as 
required by Sec.  257.105(f)(18).
    (C) EPA will publish a proposed decision on complete applications 
in a docket on www.regulations.gov for a 20-day comment period. After 
consideration of the comments, EPA will issue its decision on the 
application within sixty days of receiving a complete application.
    (D) If the application is approved, the deadline to cease receipt 
of waste will be tolled until an alternate liner demonstration is 
determined to be incomplete or a final decision under paragraph 
(d)(2)(vi) of this section is issued.
    (E) If the surface impoundment is determined by EPA to be 
ineligible to apply for an alternate liner demonstration, and the 
facility lacks alternative capacity to manage its CCR and/or non-CCR 
wastestreams, the owner or operator may apply for an alternative 
closure deadline in accordance with the procedures in Sec.  257.103(f). 
The owner or operator will be given four months from the date of the 
ineligibility determination to apply for the alternative closure 
provisions in either Sec.  257.103(f)(1) or (f)(2), during which time 
the facility's deadline to cease receipt of waste will be tolled.
    (F) Upon receipt of a decision on the application pursuant to 
paragraph (d)(2)(iii)(C) of this section, the owner or operator must 
place the decision on the application in the facility's operating 
record as required by Sec.  257.105(f)(19).
    (iv) Demonstration review. EPA will evaluate the demonstration 
package and may request additional information not required as part of 
the demonstration as necessary to complete its review. Submission of a 
complete demonstration package will continue to toll the facility's 
deadline to cease receipt of waste into that CCR surface impoundment 
until issuance of a final decision under paragraph (d)(2)(vi) of this 
section. Upon a determination that a demonstration is incomplete the 
tolling of the facility's deadline will cease and the submission will 
be rejected without further process.
    (v) Proposed decision on demonstration. EPA will publish a proposed 
decision on a complete demonstration package in a docket on 
www.regulations.gov for a 30-day comment period.
    (vi) Final decision on demonstration. After consideration of the 
comments, EPA will issue its decision on the alternate liner 
demonstration package within four months of receiving a complete 
demonstration package. Upon approval the facility may continue to 
operate the impoundment as long as the impoundment remains in detection 
monitoring. Upon detection of a statistically significant increase over 
background of a constituent listed on appendix III to this part, the 
facility must proceed in accordance with the requirements of paragraph 
(ix) of this section.
    (vii) Facility operating record requirements. Upon receipt of the 
final decision on the alternate liner demonstration pursuant to 
paragraph (vi) of this section, the owner or operator must place the 
final decision in the facility's operating record as required by Sec.  
257.105(f)(20).
    (viii) Effect of Demonstration Denial. If EPA determines that the 
CCR surface impoundment's alternate liner does not meet the standard 
for approval in this paragraph (d), the owner or operator must cease 
receipt of waste and initiate closure as determined in EPA's decision. 
If the owner or operator needs to obtain alternate capacity, they may 
do so in accordance with the procedures in Sec.  257.103. The owner or 
operator will have four months from the date of EPA's decision to apply 
for an alternative closure deadline under either Sec.  257.103(f)(1) or 
(f)(2), during which time the facility's deadline to cease receipt of 
waste will be tolled.
    (ix) Loss of authorization-(A) The owner or operator of the CCR 
unit must comply with all of the following upon determining that there 
is a statistically significant increase over background levels for one 
or more constituents listed in appendix III to this part pursuant to 
Sec.  257.94(e):
    (1) In addition to the requirements specified in this paragraph 
(d), comply with the groundwater monitoring and corrective action 
procedures specified in Sec. Sec.  257.90 through 257.98;
    (2) Submit the notification required by Sec.  257.94(e)(3) to EPA 
within 14 days of placing the notification in the facility's operating 
record as required by Sec.  257.105(h)(5);
    (3) Conduct intra-well analysis on each downgradient well to 
identify any trends of increasing concentrations as required by 
paragraph (d)(2)(ix)(B) of this section. The owner and operator must 
conduct the initial groundwater sampling and analysis for all 
constituents listed in appendix IV to this part according to the 
timeframes specified in Sec.  257.95(b);
    (4) The owner or operator may elect to pursue an alternative source 
demonstration pursuant to Sec.  257.94(e)(2) that a source other than 
the CCR unit caused the contamination, or that the statistically 
significant increase resulted from error in sampling, analysis, 
statistical evaluation, or natural variation in groundwater quality, 
provided that such alternative source

[[Page 72542]]

demonstration must be conducted simultaneously with the sampling and 
analysis required by paragraph (d)(2)(ix)(A)(3) of this section. If the 
owner or operator believes that a successful demonstration has been 
made, the demonstration must be submitted to EPA for review and 
approval. The owner or operator must place the demonstration in the 
facility's operating record within the deadlines specified in Sec.  
257.94(e)(2) and submit the demonstration to EPA within 14 days of 
placing the demonstration in the facility's operating record.
    (5) The alternative source demonstration must be posted to the 
facility's publicly accessible CCR internet site and submitted to EPA 
within 14 days of completion. EPA will publish a proposed decision on 
the alternative source determination on www.regulations.gov for a 20-
day comment period. After consideration of the comments, EPA will issue 
its decision. If the alternative source demonstration is approved, the 
owner or operator may cease conducting the trend analysis and return to 
detection monitoring. If the alternative source demonstration is 
denied, the owner or operator must either complete the trend analysis 
or cease receipt of waste. Upon receipt of the final decision on the 
alternative source demonstration, the owner or operator must place the 
final decision in the facility's operating record as required by Sec.  
257.105(f)(22).
    (B) Trend analysis. (1) Except as provided for in Sec.  257.95(c), 
the owner or operator must collect a minimum of four independent 
samples from each well (background and downgradient) on a quarterly 
basis within the first year of triggering assessment monitoring and 
analyze each sample for all constituents listed in appendix IV to this 
part. Consistent with 257.95(b), the first samples must be collected 
within 90 days of triggering assessment monitoring. After the initial 
year of sampling, the owner or operator must then conduct sampling as 
prescribed in Sec.  257.95(d)(1). After each sampling event, the owner 
or operator must update the trend analysis with the new sampling 
information.
    (2) The owner or operator of the CCR surface impoundment must apply 
an appropriate statistical test to identify any trends of increasing 
concentrations within the monitoring data. For normally distributed 
datasets, linear regression will be used to identify trends and 
determine the associated magnitude. For non-normally distributed 
datasets, the Mann-Kendall test will be used to identify trends and the 
Theil-Sen trend line will be used to determine the associated 
magnitude. If a trend is identified, the owner or operator of the CCR 
surface impoundment will use the upper 95th percentile confidence limit 
on the trend line to estimate future concentrations. The owner or 
operator will project this trendline into the future for a duration set 
to the maximum number of years established in Sec.  257.102 for closure 
of the surface impoundment.
    (3) A report of the results of each sampling event, as well as the 
final trend analysis, must be posted to the facility's publicly 
accessible CCR internet site and submitted to EPA within 14 days of 
completion. The trend analysis submitted to EPA must include all data 
relied upon by the facility to support the analysis. EPA will publish a 
proposed decision on the trend analysis on www.regulations.gov for a 
30-day comment period. After consideration of the comments, EPA will 
issue its decision. If the trend analysis shows the potential for a 
future exceedance of a groundwater protection standard, before the 
closure deadlines established in Sec.  257.102, the CCR surface 
impoundment must cease receipt of waste by the date provided in the 
notice.
    (C) If the trend analysis demonstrates the presence of a 
statistically significant trend of increasing concentration for one or 
more constituents listed in appendix IV of this part with potential to 
result in an exceedance of any groundwater protection standard before 
closure is complete, or if at any time one or more constituents listed 
in appendix IV of this part are detected at a statistically significant 
level above a groundwater protection standard, the authorization will 
be withdrawn. The provisions at Sec.  257.96(g)(3) do not apply to CCR 
surface impoundments operating under an alternate liner demonstration. 
Upon receipt of a decision that the alternate liner demonstration has 
been withdrawn, the owner or operator must place the decision in the 
facility's operating record as required by Sec.  257.105(f)(24).
    (D) The onus remains on the owner or operator of the CCR surface 
impoundment at all times to demonstrate that the CCR surface 
impoundment meets the conditions for authorization under this section. 
If at any point, any condition for qualification under this section has 
not been met, EPA or the Participating State Director can without 
further notice or process deny or revoke the owner or operator's 
authorization under paragraph (d)(2)(ix) of this section.

0
3. Amend Sec.  257.101 by revising paragraph (a)(3) to read as follows:

Sec.  257.101  Closure or retrofit of CCR units.

    (a) * * *
    (3) The timeframe specified in paragraph (a)(1) of this section 
does not apply if the owner or operator complies with the alternate 
liner demonstration provisions specified in Sec.  257.71(d) or the 
alternative closure procedures specified in Sec.  257.103.
* * * * *

0
4. Amend Sec.  257.102 by revising (d)(3)(ii) introductory text to read 
as follows:

Sec.  257.102  Criteria for conducting the closure or retrofit of CCR 
units.

* * * * *
    (d) * * *
    (3) * * *
    (ii) The owner or operator may select an alternative final cover 
system design, provided the alternative final cover system is designed 
and constructed to meet the criteria in paragraphs (d)(3)(ii)(A) 
through (C) of this section. The design of the final cover system must 
be included in the written closure plan required by paragraph (b) of 
this section.
* * * * *

0
5. Amend Sec.  257.103 by revising paragraphs (f)(1)(vi) introductory 
text, (f)(3)(i)(A) and (f)(3)(i)(C) to read as follows:

Sec.  257.103  Alternative closure requirements.

* * * * *
    (f) * * *
    (1) * * *
    (vi) Maximum time frames. All CCR surface impoundments covered by 
paragraph (f)(1) must cease receiving waste by the deadlines specified 
in paragraphs (f)(1)(vi)(A) and (B) of this section and close in 
accordance with the timeframes in Sec.  257.102(e) and (f).
* * * * *
    (3) * * *
    (i) * * *
    (A) Except as provided by Sec.  257.71(d)(2)(iii)(E) and (viii), 
the owner or operator must submit the demonstration required under 
paragraph (f)(1)(iv) of this section, for an alternative deadline to 
cease receipt of waste pursuant to paragraph (f)(1) of this section, to 
the Administrator or the Participating State Director for approval no 
later than November 30, 2020.
* * * * *
    (C) Except as provided by Sec.  257.71(d)(2)(iii)(E) and (viii), 
the owner or operator must submit the demonstration required under

[[Page 72543]]

paragraph (f)(2)(v) of this section to the Administrator for approval 
no later than November 30, 2020.
* * * * *

0
6. Amend Sec.  257.105 by adding paragraphs (f)(14) through (23) to 
read as follows:

Sec.  257.105  Recordkeeping requirements.

* * * * *
    (f) * * *
    (14) The application and any supplemental materials submitted in 
support of the application as required by Sec.  257.71(d)(1)(i)(E).
    (15) The alternative liner demonstration as required by Sec.  
257.71(d)(1)(ii)(D).
    (16) The alternative liner demonstration extension request as 
required by Sec.  257.71(d)(2)(ii)(D).
    (17) The documentation prepared for the preliminary demonstration 
as required by Sec.  257.71(d)(2)(ii)(E).
    (18) The notification of an incomplete application as required by 
Sec.  257.71(d)(2)(iii)(B).
    (19) The decision on the application as required by Sec.  
257.71(d)(2)(iii)(F).
    (20) The final decision on the alternative liner demonstration as 
required by Sec.  257.71(d)(2)(vii).
    (21) The alternative source demonstration as required under Sec.  
257.71(d)(2)(ix)(A)(4).
    (22) The final decision on the alternative source demonstration as 
required under Sec.  257.71(d)(2)(ix)(A)(5).
    (23) The final decision on the trend analysis as required under 
Sec.  257.71(d)(2)(ix)(B)(3).
    (24) The decision that the alternative source demonstration has 
been withdrawn as required under Sec.  257.71(d)(2)(ix)(C).
* * * * *

0
7. Amend Sec.  257.106 by adding paragraphs (f)(13) through (23).

Sec.  257.106  Notification requirements.

* * * * *
    (f) * * *
    (13) Provide notification of the availability of the application 
and any supplemental materials submitted in support of the application 
specified under Sec.  257.105(f)(14).
    (14) Provide notification of the availability of the alternative 
liner demonstration specified under Sec.  257.105(f)(15).
    (15) Provide notification of the availability of the alternative 
liner demonstration extension request specified under Sec.  
257.105(f)(16).
    (16) Provide notification of the availability of the documentation 
prepared for the preliminary demonstration specified under Sec.  
257.105(f)(17).
    (17) Provide notification of the availability of the notification 
of an incomplete application specified under Sec.  257.105(f)(18).
    (18) Provide notification of the availability of the decision on 
the application specified under Sec.  257.105(f)(19).
    (19) Provide notification of the availability of the final decision 
on the alternative liner demonstration specified under Sec.  
257.105(f)(20).
    (20) Provide notification of the availability of the alternative 
source demonstration specified under Sec.  257.105(f)(21).
    (21) Provide notification of the availability of the final decision 
on the alternative source demonstration specified under Sec.  
257.105(f)(22).
    (22) Provide notification of the final decision on the trend 
analysis specified under Sec.  257.105(f)(23).
    (23) Provide notification of the decision that the alternative 
source demonstration has been withdrawn specified under Sec.  
257.105(f)(24).
* * * * *

0
8. Amend Sec.  257.107 by adding paragraphs (f)(13) through (23).

Sec.  257.107  Publicly accessible internet site requirements.

* * * * *
    (f) * * *
    (13) The application and any supplemental materials submitted in 
support of the application specified under Sec.  257.105(f)(14).
    (14) The alternative liner demonstration specified under Sec.  
257.105(f)(15).
    (15) The alternative liner demonstration specified under Sec.  
257.105(f)(16).
    (16) The documentation prepared for the preliminary demonstration 
specified under Sec.  257.105(f)(17).
    (17) The notification of an incomplete application specified under 
Sec.  257.105(f)(18).
    (18) The decision on the application specified under Sec.  
257.105(f)(19).
    (19) The final decision on the alternative liner demonstration 
specified under Sec.  257.105(f)(20).
    (20) The alternative source demonstration specified under Sec.  
257.105(f)(21).
    (21) The final decision on the alternative source demonstration 
specified under Sec.  257.105(f)(22).
    (22) The final decision on the trend analysis specified under Sec.  
257.105(f)(23).
    (23) The decision that the alternative source demonstration has 
been withdrawn specified under Sec.  257.105(f)(24).
* * * * *
[FR Doc. 2020-23327 Filed 11-10-20; 8:45 am]
BILLING CODE 6560-50-P