the groundwater to concentrations that are technically practicable and
significantly reduce threats to human health or the environment. 40 CFR
258.57(f).
    EPA is proposing to adopt this same provision into part 257 with
one modification. EPA is proposing that a State Director may, on a
site-specific basis, decide not to require cleanup of part 257 Appendix
IV constituents released to groundwater from a CCR disposal unit where:
(1) The groundwater is contaminated by multiple sources and cleanup of
the CCR release would provide no significant reduction of risk; or (2)
the contaminated groundwater is not a current or potential source of
drinking water and is not hydraulically connected with waters to which
the part 257 Appendix IV constituents are migrating or likely to
migrate in a concentration(s) that would exceed the groundwater
protection standards; or (3) remediation is not technically feasible;
or (4) remediation would result in cross-media impacts. In part 258, an
owner or operator is not required to undertake source control measures
unless ordered by a State Director to do so. Although today's proposal
includes Sec.  257.97(g), which would make source control measures
mandatory in a departure from part 258, EPA is considering making the
source control measures for CCR units discretionary, similar to part
258, and seeks comment on this approach. For example, while the
Director may determine that total remediation is not required, EPA
seeks comment on whether source control measures (e.g., covers and/or
flow control measures or closure, if triggered by Sec.  257.101(a)-(c))
to minimize or eliminate further releases could not be waived. In other
words, EPA seeks comment on whether a State or EPA as the permitting
authority in a nonparticipating state, or a facility directly
implementing the requirements of this rule and subject to EPA oversight
and public notice, should have discretion not to require or perform
source control measures, including closure, in certain situations,
e.g., where there is no reasonable probability of adverse effect to
human health or the environment. In addition, partial remediation of
groundwater to concentrations that are technically feasible and that
significantly reduce risks would also be required. EPA also seeks
comment on this proposed approach. EPA describes each of these in
further detail below. Under part 258, these provisions are
discretionary. Depending on the comments EPA receives, EPA may modify
the proposed requirements at Sec.  257.97 to more closely reflect the
source control measures contained in part 258. If EPA makes any such
changes to Sec.  257.97, it may also make conforming changes to Sec.
257.101.
    As noted, the Agency is proposing that participating states may
waive the clean-up requirements where the groundwater is already
contaminated by multiple sources and clean-up of the CCR release would
provide no significant reduction of risk. In some cases, CCR units
releasing part 257 Appendix IV constituents to the groundwater may be
located in areas that already are significantly contaminated by other
sources. Where releases from the CCR units are minor compared to the
overall area-wide contamination, or where remedial measures aimed at
the CCR unit would not significantly reduce risk, EPA believes that
remediation of releases from the CCR unit would not be necessary or
appropriate. Proposed Sec.  257.97(f) is intended to address such
situations.
    Section 258.57(e)(1) applies only where sufficient evidence exists
that the groundwater is contaminated by a source other than the CCR
unit. In such cases, the owner or operator must demonstrate that
cleanup of a release from its unit would provide no significant
reduction in risk to receptors due to concentrations of constituents
from the other source. EPA has previously characterized this provision
as requiring facilities to make a robust demonstration that other
sources are significant contributors to the contamination; this
provision is not intended to provide facilities with a general
opportunity to seek a waiver from the existing cleanup requirements
under part 257.
    The Agency is not proposing to define ``significant reductions'' in
risk in this rulemaking, but consistent with the MSWLF rules, believes
the decision is best made on a case-by-case basis by the State. The
Agency understands and anticipates that states may have difficulties in
defining ``significant reduction of risk'' but expects that States will
be able to draw from their experience in implementing the analogous
requirement in Sec.  258.57(e)(1). Consistent with that provision,
participating states should take a protective approach when evaluating
requests for such a waiver. As one potential example, EPA considers
that where the facility could document that the risks to potential
receptors from non-CCR constituents would still exceed acceptable
levels of concern (i.e., risks greater than 1 x 10-4 to 1 x
10-6 for carcinogens, or an HQ greater than 1 for non-
carcinogens) even if all CCR constituents had been removed, the
facility could demonstrate there would be no significant reduction of
risk from remediation of the CCR constituents. However, EPA solicits
comment on whether there are additional criteria that

would be useful in further defining the proposed regulatory provision
under Sec.  257.97(f)(1), e.g., criteria that states have used in
implementing the analogous provision in part 258.
    Under proposed Sec.  257.97(f)(2), the State may also determine
that a hazardous constituent that has been released from a CCR unit to
groundwater does not pose a threat to human health and the environment
and, therefore, does not require remediation if: (1) The groundwater is
not a current or potential source of drinking water and (2) the
groundwater is not hydraulically connected with waters that could be a
current or potential source of drinking water or are not likely to
migrate in a concentration(s) that would exceed the groundwater
protection standards established under Sec.  257.95(h). EPA generally
interprets this to require a determination that the quality of the
water in the aquifer is such that it could not reasonably be expected
to be used as drinking water, even if treated to remove the
contaminants. The provision does not allow a waiver on the grounds that
the cost of treating the water to remove the contaminants is too high.
EPA realizes that it is difficult to predict future improvements in
treatment technologies, or to determine hydraulic connection. In
interpreting whether the aquifer meets these regulatory criteria,
States may use the approach outlined in the Agency's Ground-Water
Protection Strategy (August 1984) as guidance.\32\ As described in this
guidance, typically Class III groundwaters will be considered to meet
the requirements specified in Sec.  257.97(f)(2). Class III
groundwaters are groundwaters not considered potential sources of
drinking water. They are groundwaters with high salinity, total
dissolved solids levels over 10,000 mg/l, or are otherwise contaminated
beyond levels that allow cleanup using methods reasonably employed in
public water system treatment. These groundwaters also must not migrate
to Class I or II groundwaters or have a discharge to surface water that
could cause degradation. The need to remediate Class III groundwaters
should be assessed on a case-by-case basis. Under the second criterion,
the owner or operator must also demonstrate that the uppermost aquifer
is not hydraulically connected with a lower aquifer. The owner or
operator may nevertheless seek an exemption if it can be demonstrated
that attenuation, advection/dispersion or other natural processes can
remove the threat to interconnected aquifers. The owner or operator may
also seek the latter exemption if the contaminated zone is not a
current or potential drinking water source.
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    \32\ In addition to federal guidance, EPA is aware that States
may currently use different or more sophisticated groundwater
classification systems. In the preamble to the October 9, 1991 Final
Rule promulgating the MSW landfill standards, on the matter of
groundwater classification EPA noted that ``States are expected to
use groundwater classification and resource evaluations in making
their State decisions.'' 56 FR 50995.
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    EPA is also proposing under Sec.  257.97(f)(3) and (4) to allow the
State to determine that remediation of a release is not required when
remediation is not technically feasible or when remediation presents
unacceptable cross-media impacts. Such a determination may be made, for
example, in some cases where the nature of the hydrogeologic setting
would prevent installation and operation of an effective groundwater
pump and treat system (or other effective cleanup technology), e.g.,
where the installation and operation of such a system could potentially
increase environmental degradation by introducing the contaminant into
groundwater that was not previously affected by the release. Additional
examples of factors that may affect the efficacy of groundwater
remediation can be found in EPA Guidance for Evaluating the Technical
Impracticability of Ground-Water Restoration (OSWER Directive 9234.2-
25, September 1993).\33\ The Agency is specifically soliciting comment
on the types of situations that might warrant a determination that
remediation of a release is technically impracticable or presents
unacceptable impacts and would not, therefore, be required.
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    \33\ Additional documents related to technical impracticability
may be found at https://www.epa.gov/superfund/superfund-groundwater-groundwater-response-selection#TI_anchor.
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    A successful demonstration that remediation is not technically
feasible must document specific facts that attribute to this
demonstration. Technical infeasibilities may be related to the
accessibility of the groundwater to treatment, as well as the
treatability of the groundwater using existing treatment technologies.
If the owner or operator can demonstrate that unacceptable cross-media
impacts are uncontrollable under a given remedial option (e.g.,
movement in response to groundwater pumping) and that the no action
option is a less risky alternative, then the Director of approved
participating state may determine that remediation is not necessary.
    As noted, EPA is generally relying on the factual record developed
for the part 258 regulations to support this rule. However, the record
for that rule does not contain information that would demonstrate that
removing the existing regulatory requirement that all CCR units impose
source control would meet the RCRA section 4004(a) protectiveness
standard. These existing CCR requirements were established to address
the well-documented risks associated with CCR units, as detailed in the
risk assessment and the numerous damage cases in the rulemaking
record.\34\ The part 258 regulations apply only to landfills, while the
CCR regulations apply to both landfills and surface impoundments, the
latter being of particular concern. Surface impoundments by their very
nature pose a potential for releases to groundwater that is different
than landfills (e.g., presence of a hydraulic head) that may impact the
importance of source control for these types of units. As discussed
above, EPA requests comment on whether the proposal is appropriate, and
whether the record for either the existing CCR rule or the part 258
rules includes information, or whether other information exists, to
support adoption of the more flexible corrective action provision based
on part 258 for CCR units, which could allow an owner or operator to
undertake corrective action for unlined surface impoundments in lieu if
closure. Depending on comments received, EPA may revise this provision
to more closely reflect the existing source control and corrective
actions requirements in part 258 that would allow source control,
including closure, to be discretionary in certain situations.
---------------------------------------------------------------------------

    \34\ For example, risk estimates for unlined surface
impoundments were the highest of all CCR unit types evaluated (80 FR
21319, April 17, 2015) and EPA's documented record of confirmed
damage cases was dominated by ``wet disposal'' (e.g., impoundments;
80 FR 21456, April 17, 2015).
---------------------------------------------------------------------------

C. Modification of Groundwater Monitoring Requirements

    The current regulations at Sec.  257.90 require all CCR units,
without exception, to comply with the groundwater monitoring and
corrective action requirements of Sec. Sec.  257.90-257.98. The final
CCR rule at Sec.  257.91(a)(2) requires the installation of groundwater
monitoring wells at the waste boundary of the CCR unit.
    EPA is proposing to adopt a provision analogous to 40 CFR
258.50(b), which allows the Director of an approved participating state
to suspend the groundwater monitoring requirements under Sec.  258.51
through Sec.  258.55 if the

owner or operator can demonstrate that there is no potential for
migration of hazardous constituents from that MSWLF unit to the
uppermost aquifer during the active life of the unit and the post-
closure care period. Under part 258, the demonstration must be
certified by a qualified groundwater scientist and approved by the
Director of a participating state, and must be based upon:

    (1) Site-specific field collected measurements, sampling, and
analysis of physical, chemical, and biological processes affecting
contaminant fate and transport, and
    (2) Contaminant fate and transport predictions that maximize
contaminant migration and consider impacts on human health and
environment.

    The Agency recognizes that certain hydrogeologic settings may
preclude the migration of hazardous constituents from CCR disposal
units to groundwater resources. Requiring groundwater monitoring in
these settings would provide little or no additional protection to
human health and the environment. Therefore, EPA is proposing to
incorporate a nearly identical provision into the part 257 regulations.
This would allow the Director of a participating state to suspend the
groundwater monitoring requirements in Sec.  257.91 through Sec.
257.95 for a CCR unit upon demonstration by the owner or operator that
there is no potential for migration of hazardous constituents from the
unit to the uppermost aquifer during the active life, closure, or post-
closure periods. However, the requirements of Sec.  257.96 through
Sec.  257.98 would not be suspended. As discussed below, the provision
being proposed for the part 257 regulations would be identical to that
in the part 258 regulations with the exception for the requirement to
periodically demonstrate that conditions have not changed, that is,
there is still no migration of Appendix III or IV constituents from the
CCR unit to the uppermost aquifer.
    EPA recognizes it may be difficult for many facilities to meet the
``no potential for migration'' standard in the regulations. The
suspension of monitoring requirements is intended only for those CCR
units that are located in hydrogeologic settings in which hazardous
constituents will not migrate to groundwater during the active life of
the unit, closure, and post-closure periods. The Agency reminds readers
that the ``no migration'' waiver has been a component of both the part
258 and the RCRA subtitle C groundwater monitoring programs for many
years, and; based on its experience under these programs, the Agency
expects that cases where these criteria are met will be rare.
    The part 258 requirements allow the Director of a state program to
establish the relevant point of compliance; in an unapproved state, the
point of compliance is set by regulation at the waste management unit
boundary. EPA does not believe the record for the part 258 requirements
would support an alternative means for establishing the relevant point
of compliance for CCR groundwater monitoring wells under RCRA section
4004(a). EPA requests comment on whether a State Director or EPA in a
nonparticipating state, or an owner/operator subject to EPA oversight
and public notice, could establish an alternative point of compliance
consistent with the flexibility already allowed under the part 258
rules that would satisfy the standard of no reasonable probability of
adverse effect on human health or the environment under section
4004(a).
    In this action, EPA is not proposing to provide waivers from
groundwater monitoring requirements except where the owner or operator
in a participating state can demonstrate no potential for migration of
hazardous constituents to the uppermost aquifer during the active life
of the unit, closure, or post-closure periods. Consistent with the part
258 regulation, the Agency is proposing to allow this waiver only under
the following conditions. EPA seeks comment on the use of each of these
conditions. First, the suspension of groundwater monitoring
requirements in Sec.  257.91 through Sec.  257.95 is available only for
owners and operators of CCR units located in participating states or in
those instances where EPA is the permitting authority. The Agency has
limited the availability of the waiver because the Agency recognizes
the need for the State to review a no-migration demonstration prior to
granting a waiver from groundwater monitoring. However, the Agency
seeks comment on an approach where a technical expert could make this
demonstration (under the criteria described in the following
paragraphs) and the facility could implement without the intervention
of a permitting authority. In such an approach, the facility would keep
records and post its determination on its web site and EPA would use
the authorities in the WIIN act to oversee such a determination.
    Second, the rule requires demonstrations of no potential for
migration to be supported by both predictions that maximize contaminant
migration and actual field data collected at the site. Field testing is
necessary to establish the site's hydrogeological characteristics and
must include an evaluation of unsaturated and saturated zone
characteristics to ascertain the flow rate and pathway by which
contaminants will migrate to groundwater. Any demonstration must be
based on site-specific field measurements and sampling and analyses to
determine the physical, chemical, and biological processes affecting
the fate and transport of hazardous constituents. Site-specific
information must include, at a minimum, the information necessary to
evaluate or interpret the effects of the following properties or
processes on contaminant fate and transport:
    (1) Aquifer Characteristics, including hydraulic conductivity,
hydraulic gradient, effective porosity, aquifer thickness, degree of
saturation, stratigraphy, degree of fracturing and secondary porosity
of soils and bedrock, aquifer heterogeneity, groundwater discharge, and
groundwater recharge areas;
    (2) Waste Characteristics, including quantity, type, and origin;
    (3) Climatic Conditions, including annual precipitation, leachate
generation estimates, and effects on leachate quality;
    (4) Leachate Characteristics, including leachate composition,
solubility, density, the presence of immiscible constituents, Eh, and
pH;
    (5) Engineered Controls, including liners, cover systems, and
aquifer controls (e.g., lowering the water table). These should be
evaluated under design and failure conditions to estimate their long-
term residual performance.
    (6) Attenuation of contaminants in the subsurface, including
adsorption/desorption reactions, ion exchange organic content of soil,
soil water pH, and consideration of possible reactions causing chemical
transformation or chelation.
    (7) Microbiological Degradation, which may attenuate target
compounds or cause transformations of compounds, potentially forming
more toxic chemical species.
    Modeling may also be useful for assessing and verifying the
potential for migration of hazardous constituents. However, any models
used should be based on actual field collected data to adequately
predict potential groundwater contamination. When owners or operators
prepare a no migration demonstration, they must use transport
predictions that are based on the maximum contaminant migration (i.e.,
worst case scenario) both from the unit and through the subsurface
media. Assumptions about variables affecting transport should be biased
toward over

estimating transport and the anticipated concentrations. Assumptions
and site-specific data that are used in the fate and transport
predictions should conform with transport principles and processes,
including adherence to mass-balance and chemical equilibria
limitations. Within these physicochemical limitations assumptions
should be biased toward the objective of assessing the maximum
potential impact on human health and the environment.
    Third, the proposed rule would require the demonstrations to be
certified by a qualified professional engineer and approved by the
Director of a participating state to ensure that there is a high degree
of confidence that no contamination will reach the uppermost aquifer.
    Finally, the proposed rule would require the owner or operator of
the CCR unit to make periodic demonstrations every 10 years in order to
retain the suspension of groundwater monitoring. The Agency received
comments on suspending the groundwater monitoring requirements for
MSWLFs in part 258 that suggested EPA require periodic demonstrations
every five or ten years. See, 56 FR 51061 (October 9, 1991). The Agency
decided against requiring periodic demonstrations for MSWLFs because
the demonstration required must be extremely rigorous and because of
the additional costs associated with the continual reapplication for
the suspension. As mentioned earlier in this proposed rulemaking, the
statutory standard for the part 258 regulations is different than the
standard for the CCR regulations: The CCR regulations are based on RCRA
section 4004(a), which requires that the regulations ensure ``there is
no reasonable probability of adverse effects on health or the
environment from disposal of solid waste at such facility.'' 42 U.S.C.
6944(a). This is a risk-only standard. By contrast, EPA was authorized
to ``take into account the [facility's] practicable capability'' in
developing the part 258 regulations. 42 U.S.C. 6949a(c). Also, the part
258 regulations apply only to landfills, while the CCR regulations
apply to both landfills and surface impoundments, the latter being of
particular concern. Surface impoundments by their very nature pose a
potential for releases to groundwater that is different than landfills
(e.g., presence of a hydraulic head) that may impact the importance of
source control for these types of units. The risk assessment for the
CCR rule found that, even when key variables are controlled (e.g.,
liner type, waste type) for the long-term risks from surface
impoundments are greater than from landfills. This is because the high
and sustained hydraulic head present in these surface impoundments
drives leachate into the groundwater table at an accelerated rate.
Based on these factors, EPA is proposing to require an owner or
operator to conduct a new demonstration once every 10 years to show
that the suspension of groundwater monitoring continues to be
appropriate. See proposed Sec.  257.90(g). This new demonstration
should be submitted to the State Director one year before the existing
groundwater monitoring suspension is due to expire. If the suspension
expires for any reason, the unit must begin groundwater monitoring
according to Sec.  257.90(a) within 90 days.
    Further guidance for conducting these evaluations can be found in
the OSWER Solid Waste Disposal Facility Criteria Technical Manual for
MSWLFs (EPA530-R-93-017, 1993) and the Ground-Water Monitoring Guidance
Document for Owners and Operators of Interim Status Facilities (1983).

D. Alternate Period of Time To Demonstrate Compliance With Corrective
Action

    The current regulations at Sec.  257.98(c)(2) require that
facilities demonstrate that compliance with the groundwater protection
standards (GWPS) established under Sec.  257.95(h) have been achieved
by monitoring results documenting that concentrations of constituents
listed in Appendix IV to part 257 have not exceeded the groundwater
protection standard(s) for a period of three consecutive years using
the statistical procedures and performance standards in Sec.  257.93(f)
and (g). EPA is proposing to modify this by adopting a provision
analogous to 40 CFR 258(e)(2). Both the part 258 regulation and the
proposed Sec.  257.98(c)(4) counterpart allow the Director of a
participating state to specify an alternative length of time during
which the owner or operator must demonstrate that concentrations of
Appendix II to part 258 constituents (or in the case of the proposed
part 257 counterpart, Appendix IV to part 257 constituents) have not
exceeded the groundwater protection standard(s). Under the current part
258 regulations, the State must make this determination after taking
into consideration: (1) The extent and concentration of the release(s);
(2) behavior characteristics of the hazardous constituents in the
groundwater; (3) accuracy of monitoring or modeling techniques,
including any seasonal, meteorological, or other environmental
variabilities that may affect the accuracy; and (4) characteristics of
the groundwater.
    When establishing an alternative compliance period, the proposed
regulation would require a State to consider the following site-
specific conditions under Sec.  257.98(c)(4): (1) The extent and the
concentration of the release; (2) the behavior characteristics (fate
and transport) of the part 257 Appendix IV constituents in the
groundwater (e.g., mobility, persistence, toxicity); (3) the accuracy
of monitoring or modeling techniques, including any seasonal,
geotechnical/geophysical, meteorological, or other environmental
variabilities that may affect the accuracy; and (4) the characteristics
of the groundwater (e.g., flow rate, pH). These are the same factors
included in part 258; consideration of these factors will allow the
State to set an appropriate time period for demonstrating compliance
with the groundwater protection standards rather than relying on an
arbitrary time period for all facilities or all situations at the same
facility. In large part, EPA is relying on the longstanding experience
with these criteria under part 258 for municipal solid waste landfills.
    In summary, Sec.  257.98(c)(2) and (4) of this proposal requires
that the groundwater protection standard be achieved for a period of
three consecutive years at all points within the plume of contamination
unless an alternative period of time is established by a participating
state. Those states may set an alternative period of compliance after
taking site-specific conditions into consideration. In demonstrating
compliance with the groundwater protection standard, the owner or
operator would be required to use the statistical procedures in Sec.
257.93.

E. Length of Post-Closure Care Period

    The current regulations at Sec.  257.104(c)(1) state that the owner
or operator of a closed CCR unit must conduct post-closure care for 30
years unless at the end of the 30 years corrective action is on-going,
or the CCR unit is operating under assessment monitoring, in which case
the owner or operator must continue to conduct post-closure care until
the unit has returned to detection monitoring.
    EPA is proposing to adopt a provision analogous to 40 CFR
258.61(b), which allows the Director of a participating state to
decrease the length of the post-closure care period if the owner or
operator demonstrates that the reduced period is sufficient to protect
human health and the environment and this demonstration is approved by
the

Director of approved participating state. It also allows the Director
of the participating state to increase the length of the post closure
period if the Director determines a lengthened period is necessary to
protect human health and the environment.
    The Agency is proposing this provision to account for situations
where a 30-year post-closure care period may be inappropriate based on
site-specific conditions. Overall, providing for variances in the post-
closure care period in these states allows the flexibility to
accommodate differences in geology, climate, topography, resources,
demographics, etc. In all cases, however, these decisions must be
reviewed carefully by the State to ensure units are monitored and
maintained for as long as is necessary to protect human health and the
environment.
    In determining whether a revised post-closure care period is
warranted, one critical factor is ensuring that the cover will continue
to function effectively. EPA recognizes that no final cover, however
well-constructed, will last forever. In 1988, EPA stated that ``even
the best liner and leachate collection system will ultimately fail due
to natural deterioration . . . .'' \35\ Although any impermeable
barriers used in a final cover system will eventually fail, studies
have shown that such natural deterioration can take thousands of years
(Needham et al., 2006; Rowe & Islam, 2009).36 37 This is
consistent with the concept of bathtub (or U shaped) failure rate in
reliability analysis (Shehla & Khan, 2016).\38\ This failure pattern
begins with a wear-in period where failure rates are high due to design
and manufacturing problems. The failure rate then decreases to a low,
constant rate for a period of time before rising in the third, wear-out
phase.
---------------------------------------------------------------------------

    \35\ US EPA, ``Solid Waste Disposal Facility Criteria; Proposed
Rule,'' 53 FR 33345 (August 30, 1988).
    \36\ Needham, A.D., Smith, J.W.N., Gallagher, E.M.G. 2006. The
service life of polyethylene geomembrane barriers. Engineering
Geology 85. 82-90.
    \37\ Rowe, R.K., Islam, M.Z. 2009. Impact of landfill liner
time-temperature history on the service life of HDPE geomembranes.
Waste Management 29. 2689-2699.
    \38\ Shehla, R., & Khan, A.A. (2016). Reliability analysis using
an exponential power model with bathtub-shaped failure rate
function: a Bayes study. SpringerPlus, 5(1), 1076. http://doi.org/10.1186/s40064-016-2722-3.
---------------------------------------------------------------------------

    Though this wear-out phase may take thousands of years, the wear-in
phase for waste management unit covers is much shorter. In the context
of CCR units, the wear-in phase of a closed unit would be due to
imperfections in covers, either from a manufacturing defect or faulty
installation. Manufacturing defects may include items such as pin
holes, whereas faulty installation may be the result of a tear or
failure to properly seal joints (Bonaparte et al, 1989).\39\
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    \39\ Bonaparte, R., J.P. Giroud, and B.A. Gross. 1989. Rates of
leakage through landfill liners. Geosynthetics 1989 Conference. San
Diego, CA.
---------------------------------------------------------------------------

    Settlement resulting from factors, such as the gradual dissolution
of more soluble components within the ash mixture, is also a potential
issue. Depressions caused by settlement may lead to ponding and should
be filled with soil. Excessive settlement may warrant reconstructing or
adding to portions of the infiltration layer. Settlement can also
damage the cover through tension cracks and tears in the synthetic
membrane. For example, topographic surveys of the unit(s) may be used
every few years until settlement behavior is established, to determine
whether settlement has occurred.
    Consequently, EPA is proposing to require that part of determining
whether a shorter post-closure care period will protect human health
and the environment, a state must ensure that the post-closure care
period is long enough to detect such issues. This would require the
state to consider not only the type of cover placed on the unit (e.g.,
compacted soil), but also the placement of the groundwater monitoring
wells with respect to the waste management unit. For instance, where a
waste management unit is close to the groundwater table and the
groundwater monitoring wells are located at the unit boundary, one
would generally expect transit time of any contamination to be short,
and thus a shorter post-closure monitoring period might be sufficient
to catch wear-in defects in the cover system. However, where the unit
is located further from the groundwater table, constituents may not
have sufficient time to reach the monitoring wells under such a
curtailed post-closure period.
    In addition, under the current CCR regulations, once detection
monitoring yields a statistically significant increase above background
levels of any Appendix III constituent, assessment monitoring is
triggered, and the unit continues to be subject to the rule's post-
closure care requirements so long as the CCR unit is operating under
assessment monitoring. Section 257.104(c)(2). EPA is not proposing to
amend this requirement, or to allow States to do so as part of this new
provision. Thus, the State could not allow a facility to end the post-
closure care period, once the detection of contamination above
background triggers assessment monitoring. This would hold, even if the
State had previously authorized a shorter post-closure care period. EPA
is proposing to include language in this provision that clarifies how
these two requirements interact.

F. Allowing Directors of Participating States To Issue Certifications
in Lieu of Requiring a PE Certification

    To ensure that the RCRA subtitle D requirements would achieve the
statutory standard of ``no reasonable probability of adverse effects on
health and the environment'' in the absence of regulatory oversight,
the current CCR regulations require facilities to obtain third party
certifications and to provide enhanced state and public notifications
of actions taken to comply with the regulatory requirements.
Specifically, in the final CCR rule EPA required numerous technical
demonstrations made by the owner or operator be certified by a
qualified professional engineer (PE) in order to provide verification
of the facility's technical judgments and to otherwise ensure that the
provisions of the rule were properly applied. While EPA acknowledged
that relying upon a third party certification was not the same as
relying upon a state or federal regulatory authority and was not
expected to provide the same level of independence as a state permit
program, the availability of meaningful third party verification
provided critical support that the rule would achieve the statutory
standard, as it would provide a degree of control over a facility's
discretion in implementing the rule. However, the situation has changed
with the passage of the WIIN Act, which offers the opportunity for
State oversight under an approved permit program. To reflect that, EPA
is proposing to revise the regulations to allow the Director of a state
with an approved CCR permit program (a participating state) to certify
that the regulatory criteria have been met in lieu of the exclusive
reliance on a qualified PE. EPA expects that States will generally rely
on the expertise of its own engineers to evaluate whether the technical
criteria have been met. Alternatively, States might choose to retain
the required certification by a qualified PE and use its own expertise
to evaluate that certification. Finally, EPA notes that under the
existing regulations, a facility may already rely on a certification
provided by a qualified PE in a State agency, who reviews the facility
actions as part of a purely State-law mandated process. Thus, EPA is
confident that the

additional layer of oversight provided by the State under this proposal
will be at least as protective than the status quo under the existing
regulations.

G. Revision To Allow the Use of CCR During Certain Closure Situations

    EPA is proposing to revise the current regulations to allow the use
of CCR in the construction of final cover systems for CCR units closing
pursuant to Sec.  257.101 that are closing with waste-in-place. EPA is
also proposing specific criteria that the final cover system must meet
in order to allow for the placement of CCR in the final cover system.
EPA is proposing two performance standards: One that applies directly
to facilities in any ``non-participating state'' and a second that
applies to facilities that operate in states with an approved CCR
permit program (``participating'' state). Specifically, EPA is
proposing to allow for the continued placement of CCR in units
triggered for closure to construct a cover system under the following
conditions: (1) Only CCR generated on-site may be used in the
construction of the cover system; (2) CCR may be used exclusively for
the purposes of grading and contouring of the cover system; (3) CCR
must be placed within the vertical plane of the boundary of the unit;
and (4) must be at either no steeper than a 5 percent grade or at a
steeper grade, as determined by the Director of an approved program
based on a stability analysis. These criteria are intended to ensure
that the CCR utilized in construction of the final cover system does
not exceed the necessary amount for grading and contouring.
    The current CCR rules require that certain units must close for
cause, as laid forth in Sec.  257.101(a)-(c). As written, the
regulation expressly prohibits ``placing CCR'' in any units required to
close for-cause pursuant to Sec.  257.101. This includes unlined CCR
surface impoundments whose groundwater monitoring shows an exceedance
of a groundwater protection standard (Sec.  257.101(a)(1)); existing
CCR units that do not comply with the location criteria (Sec.
257.101(b)(1)); and CCR surface impoundments that are not designed and
operated to achieve minimum safety factors (Sec.  257.101(b)(2) and
(c)(1)). Note that the rule does not distinguish between placement that
might be considered beneficial use and placement that might be
considered disposal. All further placement of CCR into the unit is
prohibited once the provisions of Sec.  257.101 are triggered. By
contrast, the regulations do not restrict further placement or use of
CCR when the unit is closing under other provisions.
Proposal for Closure With CCR
    After publication of the final rule, EPA received numerous requests
that EPA clarify whether use of CCR in completing the closure of a unit
was permitted under the regulation, either as part of a closure plan or
under the theory that such an activity was ``beneficial use.'' After
evaluating the issue, EPA is proposing an exemption that would allow
further placement of CCR in a CCR unit closing pursuant to Sec.
257.101 for the purposes of construction of the final cover system. EPA
is not proposing any other revisions to the existing closure
requirements; therefore, owners and operators who choose to place CCR
as part of the final cover system as part of closure ``for cause'' will
still need to comply with all of the existing closure requirements in
Sec. Sec.  257.101-104.
    EPA is proposing this revision because there are environmental and
health benefits in allowing use of CCR in this fashion, and as
discussed below in more detail, provided the conditions outlined in
this rule are met, the existing information demonstrate that the use of
CCR in this fashion would not measurably affect the risks from the
unit. Allowing the use of on-site CCR in lieu of other material to
construct the cover furthers the general goal in Sec.  257.102(d)(1)(v)
of closing as quickly as possible. As EPA identified in the final rule,
the process for procuring at-specification earthen material in the
volumes necessary for the final cover system construction can
complicate completion of closure requirements within the required time
frames. This was explicitly described as a factor that could support an
extension of the closure deadlines under Sec.  257.102(f)(2)(i)(C).
Thus, this proposed revision is expected to allow facilities to
complete closure more quickly, and accordingly realize reduced risks
more quickly.
    This proposal is a narrow modification of the Sec.  257.101
prohibition on CCR placement, and contains four requirements to ensure
that the use of CCR is to accelerate closure rather than merely allow
the facility continue the disposal of CCR in a deficient unit. First,
the material placed under this exemption must have been generated on-
site and be present at the time of closure. Second, the material may
only be used for the grading and contouring of the cover system, not to
fill up a partially full unit. Third, the placement of the material
must be within the boundary or the vertical plane of the boundary of
the waste management unit. Finally, the material may only be used to
construct a cover at either no steeper than a 5 percent grade or at a
steeper grade, as determined by the Director of an approved program (or
EPA where it is the permitting authority). Each of these requirements
is discussed further below.
    On-site materials. EPA is proposing that all CCR material utilized
for construction of the final cover system must have been generated by
the facility, i.e., by the coal-fired boilers that generated
electricity at the facility and associated air pollution control
devices, and that the CCR be located at the facility since the time of
generation. CCR sourced exclusively from on-site will allow for timely
construction of the final cover system. Moreover, EPA does not intend
this proposed rule to allow owners and operators to continue disposal
into a waste management unit that is closing for cause pursuant to
Sec.  257.101. Limiting the source of material will help to ensure
that. Rather, the exemption is meant to allow for the genuine use of
available materials for the closure of a waste management unit.
    For grading and contouring. EPA is also proposing to limit the
exemption to the design and construction of the final cover system. As
noted previously, Sec.  257.102(d)(2) requires that dewatering and
stabilization be achieved prior to installation of a cover, and Sec.
257.102(d)(3) requires that several protective layers be constructed at
the uppermost areas of the final cover system. As a practical matter,
these two existing provisions (which EPA is not proposing to modify or
take comment on) would effectively limit the placement of CCR to
grading and contouring. Nevertheless, to avoid confusion, EPA is
proposing to include a specific condition to make this explicit. For
the purposes of this rule, EPA considers grading and contouring as
activities specifically related to creating elevation differences and
travel pathways to encourage free drainage of liquids out of and away
from the CCR surface impoundment. Accordingly, EPA is proposing to
define grading to mean placement of CCR for the sole purpose of
creating differences in elevation to support positive stormwater
drainage. EPA is also proposing to define contouring to mean placement
of material to provide a continuous downward slope on the surface of a
drainage area (i.e., the final cover system), except for erosion
control features (e.g., swales, contour banks).
    This proposal would not allow placement of CCR for the purposes of
waste stabilization or to otherwise fill

the unit to capacity. Placement of CCR for these purposes would involve
the placement of substantial volumes of CCR into a leaking or otherwise
deficient unit, and EPA lacks information that such further placement
would be protective. To achieve this, EPA is proposing different
criteria based on the construction of the unit. Many surface
impoundments consist of an incised portion, or portion which is
excavated below the surrounding grade. Incised units are units that
hold an accumulation of CCR entirely below the adjacent natural ground
surface, and do not consist of any constructed diked portion. For
incised CCR surface impoundments, EPA is proposing that any CCR
utilized for the final cover system must be placed above the highest
elevation of the surrounding natural ground surface where the CCR unit
was constructed.
    EPA intends for this requirement to account for the preexisting
topography in the area where the incised CCR unit was constructed. The
owner or operator would be responsible for determining the preexisting
topography of the CCR unit through means of historical documentation or
by identifying the highest point of the perimeter of the excavated
portion of the unit.
    A primary purpose of a final cover system is to encourage free
surface drainage in order to limit infiltration from precipitation into
the underlying waste. CCR units with incised portions can present an
issue with free drainage of liquids because much of the unit is located
below the surrounding grade and does not allow for drainage by gravity,
i.e., the drainage must occur mechanically, by evapotranspiration, or
by infiltration. Placement of CCR below the highest elevation of the
surrounding topography would no longer serve the purpose of encouraging
drainage, and therefore would not be considered part of constructing
the final cover system.
    For all other units, including CCR surface impoundments that
consist of a diked portion, e.g., diked impoundments, cross-valley
impoundments, side-hill impoundments, or some combination thereof, EPA
is proposing to require the owner or operator to establish a baseline
elevation above which all CCR would need to be placed when constructing
the final cover system. EPA is proposing that this baseline elevation
be defined as the highest elevation of CCR in the unit, following
dewatering and stabilization as required by Sec.  257.102(d)(2).\40\
From that point forward, CCR material may only be placed above that
elevation for grading and contouring.
---------------------------------------------------------------------------

    \40\ As noted, under the existing regulations the owner or
operator must first breach and dewater the CCR unit, allowing for
free drainage of water, sediment, or slurry out of the CCR surface
impoundment via surface runoff, prior to construction of the final
cover system. Additionally, if the owner or operator intends to
leave waste-in-place, the owner or operator must ``preclude the
probability of future impoundment of water, sediment, or slurry,''
per the requirements of Sec.  257.102(d)(1)(ii).
---------------------------------------------------------------------------

    These requirements are designed to establish clear and objective
geometric boundaries for the permissible placement of CCR. With these
two performance standards, EPA is effectively establishing a ``lowest
bound'' plane; placement below that elevation would be considered to be
disposal, and would still be prohibited. EPA is also proposing to
establish an upper bound to ensure that only the amount of CCR
necessary for grading and contouring is used. The ``upper bound'' is
represented by the maximum final grade of the final cover system of
1:20, i.e., 5 percent (discussed further below). Furthermore, the
``vertical plane'' criteria discussed later in this preamble would also
establish ``horizontal bounds'' for placement of CCR material in the
cover system. In order to fulfill the ``free drainage'' criteria set
forth in Sec.  257.102(d)(1)(ii), the geometry of the waste in the unit
must allow for free drainage of all water, sediment, and slurry from
any point within the CCR surface impoundment out of the breached
portion of the embankment.
    Collectively, these criteria are designed to ensure owners and
operators place only the amount of CCR necessary to achieve adequate
grading and contouring for free drainage.
    For example, this proposal would not allow the owner or operator to
raise the breached invert elevation and place CCR material above the
previously placed ``waste-in-place'' CCR and effectively raise the
invert elevation for drainage. EPA intends for the final level of CCR
within the CCR unit to essentially be the ultimate height of the
surface of the final cover system, with allowance for limited addition
of material to ensure effective drainage from the unit. EPA does not
intend for this proposal to allow the facility to unnecessarily raise
the invert elevation of the breached portion of the embankment, as a
means of further disposal of CCR in the interim space between initial
invert and adjusted invert elevations.
    Within the vertical plane. EPA is proposing that CCR used for
construction of the final cover system may not be placed outside the
vertical plane. The vertical plane for non-incised units is established
as the line which extends from the intersection between the crest of
the CCR within the surface impoundment and the berm or dike of the CCR
surface impoundment. For incised CCR surface impoundments, the vertical
plane is established as the line that extends at the intersection where
the cap of the CCR surface impoundment with a slope of no steeper than
5 percent meets the natural topography of the land prior the
construction of the CCR unit. Placement beyond this boundary would
constitute a lateral expansion as defined in Sec.  257.53.\41\ EPA is
proposing this requirement in order to prevent the potential release of
CCR constituents outside of the waste boundary without the protections
EPA deliberately included in the final rule for such lateral
expansions.
---------------------------------------------------------------------------

    \41\ Lateral expansion means a horizontal expansion of the waste
boundaries of an existing CCR landfill or existing CCR surface
impoundment made after October 19, 2015.
---------------------------------------------------------------------------

    At no steeper than a 5 percent grade. EPA is proposing that the
final cover system using CCR for grading and contouring be constructed
with slopes no steeper than 1:20. This ratio of vertical rise to
horizontal rise is equal to a 5 percent grade. EPA has identified 5
percent to generally be the maximum necessary grade to promote positive
drainage in a vegetated slope runoff, as steeper grades may lead to
erosion and deterioration of the final cover system.\42\ EPA is
proposing a maximum grade for the final cover system to minimize the
potential for abuse whereby a facility might unnecessarily grade a
cover steeply in order to dispose of additional CCR. EPA intends the
grade of the final cover system to allow for free drainage to the
invert elevation of the breached portion of the embankment.
---------------------------------------------------------------------------

    \42\ USEPA, Solid Waste Disposal Facility Criteria-Technical
Manual, EPA Document EPA530-R-93-017.
---------------------------------------------------------------------------

    However, in rare instances it may be possible that a cover requires
a steeper grade. Consequently, EPA is proposing that the Director of a
participating state may approve a grade steeper than 5 percent in a
permit if such a grade is necessary for the proper function of the
cover system. To support a steeper grade, a stability analysis must be
performed to evaluate possible erosion potential. A stability analysis
looks at the ability of soil to resist sliding on itself on the slope.
The analysis, at a minimum, must evaluate: (1) The site geology, (2)
characterize soil shear strength, (3) construct a slope stability
model, (4) establish groundwater and seepage conditions, if any, (5)
select loading conditions, (6) locate critical

failure surface, and (7) iterate until minimum factor of safety is
achieved.
    Finally, EPA recently issued an interpretation that under the
current regulations, the prohibition on the placement a unit closing
for cause did not preclude the movement of additional wastes
(stormwater and associated/accompanying CCR) between the units that
operate as part of a multiunit treatment system. The current
regulations allow the facility to treat such units as a single unit.
See, e.g., Sec.  257.91(d)(1). Based the longstanding interpretation
that EPA does not regulate the movement of wastes within a unit, EPA
concluded that where the impoundments are being treated as a singular
system, the movement of CCR within that system (i.e., from one
impoundment to another) would not be considered ``placing CCR'' under
the prohibitions of Sec.  257.101. Under this same logic, a facility
could conceivably consolidate the CCR from other units in the system
into a single unit, even though the unit was deficient. There can be
benefits to such a practice; for example, it may facilitate clean
closure and allow owners and operators to focus their long term
monitoring, care, and cleanup obligations on a single unit rather than
many units. And presuming the unit meets all of the performance
standards for closure with waste in place, it may be the risks
associated with such consolidation are acceptable. However, there are
also potentially significant risks associated with the continued
placement of large volumes of CCR in a deficient unit. As discussed in
the next section, although EPA has preliminarily concluded that the use
of CCR in the construction of the cover system will meet the RCRA
section 4004(a) standard, there were limitations in the assessment that
raise questions about further extrapolation of that assessment to
support the placement of large volumes of CCR in these units (e.g.,
EPA's risk assessment did not model the addition of CCR to partially-
filled leaking units). Thus an interpretation that allowed
consolidation of CCR into a single unit of a multi-unit system could be
seen as inconsistent with the approach outlined in this proposal.
    EPA has not determined whether allowing such a practice meets the
statutory standard, and is therefore soliciting comment on two
potential alternatives. Under one approach EPA would rely on its
longstanding interpretation to allow the consolidation of CCR from
units operating within a multi-unit system, when the facility treats
the system as a single unit for purposes of closure (i.e., all units
within the system are closing). Alternatively, EPA would revise the
regulations to explicitly clarify that only the use of CCR for purposes
of grading and contouring is permitted, even between units within a
multi-unit system closing for cause. Note that under either approach,
EPA does not intend to revise its interpretation that the movement of
stormwater (and associated CCR) between units within a multi-unit
system that is closing for cause is permissible. EPA is concerned about
the potential risks associated with the continued placement of large
volumes of CCR, and similar concerns are not raised by the movement of
stormwater and de minimis amounts of CCR between units in the process
of clean closing.
Analytic Support of Risk Assessment Results
    U.S. EPA (2009) \43\ used a response-surface regression method to
derive a statistical model for groundwater concentration (as the
dependent variable) based on the input parameters from the
probabilistic analysis (as independent variables). Concentration,
rather than risk, was chosen as the dependent variable for the
sensitivity analysis because the additional exposure factors used to
calculate human health risk from environmental concentration (e.g.,
body weight) have well established, peer-reviewed distributions based
on EPA policy. The outputs of the sensitivity analysis were goodness-
of-fit values used to determine the relative importance of each input
parameter. The most sensitive parameters identified are presented in
Table 1.
---------------------------------------------------------------------------

    \43\ U.S. EPA (Environmental Protection Agency). 2009.
Sensitivity Analysis for the Coal Combustion Waste Risk Assessment.
Draft Technical Report. Prepared by RTI International for U.S. EPA,
Office of Solid Waste, Washington, DC.

                                          Table 1--Sensitive Parameters
----------------------------------------------------------------------------------------------------------------
               Pathway:                                GW to DW pathway                      GW to SW pathway
----------------------------------------------------------------------------------------------------------------
            Constituents:                  All constituents         Strongly sorbing         All constituents
----------------------------------------------------------------------------------------------------------------
Sensitive Parameters.................   Infiltration     Kd value......   Infiltration
                                        rate.                    Depth to         rate.
                                        Leachate         groundwater.             Leachate
                                        concentration.                                    concentration.
                                        Hydraulic        Distance to      Water body
                                        gradient.                receptor well.           flow rate.
                                        Hydraulic
                                        conductivity..
----------------------------------------------------------------------------------------------------------------
Note: GW = Groundwater; DW = Drinking Water; SW = Surface Water.

    As seen in the table above, the groundwater to drinking water
exposure pathway had more input parameters that were highly sensitive
(seven) than the groundwater to surface water exposure pathways
(three). The most sensitive parameters for the groundwater to drinking
water pathways were parameters that impact flux (infiltration rate and
leachate concentration) and groundwater flow (hydraulic conductivity
and gradient). When modeling strongly sorbing constituents, the
Kd values and distance to receptor also become important.
The most sensitive parameters for the groundwater to surface water
exposure pathways were parameters impacting flux (infiltration rate to
groundwater and leachate concentration) and the water body flow rate.
    Depth to groundwater was a sensitive parameter for strongly sorbing
constituents. However, the sensitivity analysis did not find total
waste depth (i.e., total thickness of CCRs disposed in a unit filled to
capacity) to be a sensitive parameter for closed landfills and surface
impoundments. However, EPA sought to verify this through further
analysis of the final risk assessment results (U.S. EPA, 2014).\44\
---------------------------------------------------------------------------

    \44\ U.S. EPA. 2014. Human Health and Ecological Risk Assessment
of Coal Combustion Residuals. Final. Office of Resource Conservation
and Recovery. December. RIN: 2050-AE81.
---------------------------------------------------------------------------

    The risks EPA sought to further evaluate were those from surface
impoundments closed for cause with waste in place. In Appendix K of the
final risk assessment, EPA modeled dewatered surface impoundments post-
closure with waste in place as

equivalent to closed landfills. Because the results driving EPA's final
rule were those for trivalent arsenic [As(III)] cancer risks, EPA
selected As(III) cancer risk results from landfills as the appropriate
results on which to conduct this sensitivity analysis.
    EPA used the probabilistic model inputs for waste depth to
calculate 25th, 50th, and 75th percentile waste depths. These cutoffs
were used to filter the model runs into four quartiles. For each
quartile EPA calculated a 90th percentile As(III) cancer risk. Below
are the As(III) cancer risk results EPA obtained when filtering the
landfill risk results for the depth of the waste. As waste depth
changed, EPA did not see significant changes in risk for any liner
type. This confirms the findings of the sensitivity analysis where
depth was not shown to be a sensitive parameter.

                    Table 2--90th Percentile As(III) Cancer Risks Across Waste Depth Quartile
----------------------------------------------------------------------------------------------------------------
                                                   1st Quartile    2nd Quartile    3rd Quartile    4th Quartile
----------------------------------------------------------------------------------------------------------------
Liner Type:
    Unlined.....................................        1.50E-05        1.28E-05        2.66E-05        1.79E-05
    Clay Lined..................................        1.28E-05        1.11E-05        1.32E-05        1.93E-05
    Composite...................................        1.39E-20        5.34E-29        3.84E-27       <1.00E-30
----------------------------------------------------------------------------------------------------------------

    EPA also notes that the volume of infiltration from precipitation
relative to the volume of waste present in a unit is very small. This
would lead to a low liquid-to-solid (L/S) ratio for water passing
through landfills and dewatered surface impoundments. The low L/S ratio
ensures that the leachate is saturated with constituent mass before it
exits the bottom of the landfill or surface impoundment. Because the
leachate is in equilibrium with the waste, the addition of more mass
would not further increase leachate concentrations. Instead, the
increased total mass would affect the time necessary for constituent
mass to fully deplete from the waste. A majority of the model runs for
arsenic already reached a steady state concentration at the well within
the modeled timeframe. Therefore, an increase in leaching duration
would not substantially alter long-term risks.
    The addition of larger volumes of ash for purposes other than
expediting closure would result in a greater amount of time without a
cap and other appropriate controls in place. This would result in
greater opportunity for precipitation to infiltrate into the unit prior
to closure. The additional volume of water would increase the hydraulic
head within the unit and, ultimately, the rate of infiltration down to
the groundwater table. EPA identified infiltration to groundwater as
one of the most sensitive variables when modeling risks. Thus, EPA
concludes that the addition of ash for purposes other than expediting
closure has the potential to increase the transport of constituent mass
to groundwater and the associated risks.
    Under this proposal, utilities could add ash to construct the cover
system for closure of a unit for the purpose of achieving the necessary
grade to safely close with waste in place. A review of both the 2009
sensitivity analysis and the final risk assessment found that the
comparatively minor addition of CCR mass applied solely for grading
purposes would not alter potential risks to receptors. Therefore, EPA
finds that the use of ash for grading would remain protective of human
health and the environment.

V. The Projected Economic Impacts of This Action

A. Introduction

    EPA estimated the costs and benefits of this action in a Regulatory
Impact Analysis (RIA) which is available in the docket for this action.
The RIA estimates costs and cost savings attributable to the provisions
of this action against the baseline costs and cost savings of the 2015
CCR final rule. The RIA estimates that the net annualized impact of
these eleven provisions over a 100 year period of analysis will be cost
savings of between $32 million and $100 million when discounting at 7
percent and cost savings between $25 million and $76 million when
discounting at 3 percent. This action is considered an economically
significant action under Executive Order 12866.

B. Affected Universe

    The universe of affected entities for this rule consists of the
same entities affected by EPA's 2015 CCR final rule. These entities are
coal-fired electricity generating plants operated by the electric
utility industry. They can be identified by their North American
Industry Classification System (NAICS) designation 221112 ``Fossil Fuel
Electric Power Generation''. The RIA estimates that there are 414 coal-
fired electricity generating plants operating 922 CCR management units
(landfills, disposal impoundments, and storage impoundments) that will
be affected by this rule.

C. Baseline Costs

    The baseline costs for this rule are the costs of compliance with
EPA's 2015 CCR final rule, as the provisions of this rule modify the
provisions of the 2015 CCR final rule or modify the implementation of
the 2015 CCR rule by WIIN Act participating states. The RIA for the
2015 CCR final rule estimated these costs at an annualized $509 million
when discounting at 7 percent and an annualized $735 million when
discounting at 3 percent.

D. Cost Savings, Other Benefits, and Adjustments to the Baseline

    The RIA estimates costs and costs savings for the four proposals
associated with the 2015 CCR rule judicial remand as well as the six
alternative performance standards that will apply in participating
states under the WIIN Act, and the use CCR during certain closure
situations. The RIA estimates that the net annualized impact of these
eleven provisions over a 100 year period of analysis will be an
annualized cost savings of between $32 million and $100 million when
discounting at 7 percent, and an annualized cost savings of between $25
million and $76 million when discounting at 3 percent.
    The RIA also estimates potential adjustments to the baseline costs
of the CCR final rule due to plant closures that occurred after the
rule was published but before the effective date of the rule. The RIA
accompanying the 2015 CCR final rule assigned compliance costs to these
plants, which they are exempt from because they closed before the final
rule's effective date. In all, 23 plants closed before the effective
date of the final rule that were not accounted for in 2015 final rule
RIA. The annualized compliance costs avoided for these plants equals
between $22 million and $25 million per year when discounting at 7
percent and between $22 million and $31 million when

discounting at 3 percent. This cost adjustment is detailed in the RIA
that accompanies this rulemaking, however it is not factored into the
baseline or the benefit estimates for this rule to keep comparisons
with the 2015 CCR final rule straight forward.

E. Solicitation of Comments on the Projected Economic Impacts

    EPA is soliciting comments on the following aspects of the
Regulatory Impact Analysis (RIA), which is available in the docket for
this rulemaking. The Agency is soliciting comment primarily on the
assumptions and the data sources used in the analysis.
     Do you have information that would refine the RIA
assumptions about the number of facilities both in and serving affected
NERC regions that would request alternative closure under Additional
Provision 1 (the amendment discussed in Unit III.D of this preamble)?
     Do you have information that would refine the RIA
assumption that facilities seeking alternative closure requirements
under Additional Provision 1 (the amendment discussed in Unit III.D of
this preamble) would delay closure by five years (the maximum allowed
under the rule)?
     Do you have information that would refine the RIA
assumptions about the maximum or minimum number of states that would
likely adopt alternative performance standards under the WIIN Act?
     Do you have information that would refine the RIA
assumptions about the changes in total corrective action costs for a
release due to the Alternative Performance Standard 1 (the amendment
discussed in Unit IV.A of this preamble)?
     Do you have information that would refine the RIA
assumptions about the total number of CCR units that may avoid
corrective action costs due to the Alternative Performance Standard 2
(the amendment discussed in Unit IV.B of this preamble)?
     Do you have information that would refine the RIA
assumptions about the number of units that will receive a ``no
migration'' waiver under Alternative Performance Standard 3 (the
amendment discussed in Unit IV.C of this preamble)?
     Do you have information that would refine the RIA
assumption that states adopting Alternative Performance Standard 4 (the
amendment discussed in Unit IV.D of this preamble) would on average
reduce the post-remedy monitoring from three years to one year?
     Do you have information that would refine the RIA
assumption that states adopting Alternative Performance Standard 5 (the
amendment discussed in Unit IV.E of this preamble) would on average
reduce the period from 30 years to five years?
     Do you have information that would refine the RIA
assumptions about the total number of CCR units that would use CCR as
allowed under Additional Provision 2 (the amendment discussed in Unit
IV.G of this preamble)?
     Do you have information that would refine the RIA
assumptions about the average annual number of CCR units closing (RIA
page 4-14)?
     Do you have information that would refine the RIA
assumptions about the estimated tonnage of CCR that could be used for
closure (RIA page 4-14)?
     Do you have information that would refine the RIA
description and estimates of impacts related to interactions among CCR
Remand Rule provisions (RIA pp. 5-1 through 5-3)?

VI. Statutory and Executive Order (EO) Reviews

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

    This action is a significant regulatory action that was submitted
to the Office of Management and Budget (OMB) for review. Any changes
made in response to OMB recommendations have been documented in the
docket. The EPA prepared an analysis of the potential costs and
benefits associated with this action. This Regulatory Impact Analysis
(RIA), entitled Regulatory Impact Analysis; EPA's 2017 RCRA Proposed
Rule; Disposal of Coal Combustion Residuals from Electric Utilities;
Amendments to the National Minimum Criteria (October 2017), is
summarized in Unit V of this preamble and the RIA is available in the
docket for this proposal.

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

    This action is expected to be an Executive Order 13771 deregulatory
action. Details on the estimated cost savings of this proposed 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 1189.27, OMB
control number 2050-0053. This is an amendment to the ICR approved by
OMB for the Final Rule: Hazardous and Solid Waste Management System;
Disposal of Coal Combustion Residuals from Electric Utilities published
April 17, 2015 in the Federal Register at 80 FR 21302. You can find a
copy of the ICR in the docket for this action, and it is briefly
summarized here. This rulemaking, specifically the provision clarifying
the type and magnitude of non-groundwater releases that would require a
facility to comply with some or all of the corrective action procedures
set forth in Sec. Sec.  257.96-257.98, reduces the paperwork burden
attributable to provisions of the April 17, 2015 CCR Final Rule.
    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: 414.
    Frequency of response: The frequency of response varies.
    Total estimated burden: EPA estimates the total annual burden to
respondents to be a reduction in burden of approximately 4,267 hours
from the currently approved burden. Burden is defined at 5 CFR
1320.3(b).
    Total estimated cost: The total estimated annual cost of this rule
is a cost savings of approximately $5,713,027. This cost savings is
composed of approximately $519,832 in annualized avoided labor costs
and $5,193,195 in avoided capital or operation and 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 amounting to approximately $32 million per
year to $100 million per year when discounting at 7 percent and
annualized over 100 years. It is expected to result in net cost savings
of between $25 million and $76 million when discounting at 3 percent
and annualized over 100 years. Savings will accrue to all regulated
entities, including small entities. Further information on the economic
effects of this action can be found in Unit V of this preamble and in
the Regulatory Impact Analysis, which is available in the docket for
this action. 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. The costs involved in this action are imposed only by
participation in a voluntary federal program. UMRA generally excludes
from the definition of ``federal intergovernmental mandate'' duties
that arise from participation in a voluntary federal program.

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. For the ``Final Rule: Hazardous and Solid Waste
Management System; Disposal of Coal Combustion Residuals from Electric
Utilities'' published April 17, 2015 in the Federal Register at 80 FR
21302, EPA identified three of the 414 coal-fired electric utility
plants (in operation as of 2012) which are located on tribal lands;
however, they are not owned by tribal governments. These are: (1)
Navajo Generating Station in Coconino County, Arizona, owned by the
Arizona Salt River Project; (2) Bonanza Power Plant in Uintah County,
Utah, owned by the Deseret Generation and Transmission Cooperative; and
(3) Four Corners Power Plant in San Juan County, New Mexico owned by
the Arizona Public Service Company. The Navajo Generating Station and
the Four Corners Power Plant are on lands belonging to the Navajo
Nation, while the Bonanza Power Plant is located on the Uintah and
Ouray Reservation of the Ute Indian Tribe. Moreover, since this action
is expected to result in net cost savings to affected entities
amounting to approximately $32 million per year to $100 million per
year when discounting at 7 percent and annualized over 100 years, or in
net cost savings of between $25 million per year and $76 million per
year when discounting at 3 percent and annualized over 100 years, it
will not have substantial direct effects on one or more 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 the EPA
does not believe the environmental health or safety risks addressed by
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 EO 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
in the Federal Register at 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
adversely affect these requirements and, in fact it enhances the
groundwater monitoring requirements by adding boron to the list of
constituents in Appendix IV that trigger corrective action. Thus, 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 proposed 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 proposed 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.
    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.

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.

    Dated: March 1, 2018.
E. Scott Pruitt,
Administrator.

    For the reasons set out in the preamble, title 40, chapter I, of
the Code of Federal Regulations is proposed to be amended as follows:

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

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

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

0
2. Section 257.53 is amended by:
0
a. Adding in alphabetical order the definition of ``Contouring'',
``Engineered slope protection measures'', ``Grading'', ``Grassy
vegetation'', ``Non-groundwater releases'', ``Participating state'',
``Pertinent surrounding areas'', ``Vegetative height'', and ``Woody
vegetation'' in alphabetical order.
0
b. Revising the definition of ``Slope protection'' and ``State
director.''
    The revisions and additions read as follows:

Sec.  257.53  Definitions.

* * * * *
    Contouring means the placement of material to provide a continuous
downward slope on the surface of a drainage area, except for erosion
control features (e.g., swales, contour banks).
* * * * *
    Engineered slope protection measures means non-vegetative cover
systems, which include but are not limited to rock riprap, concrete
revetments, vegetated wave berms, concrete facing, gabions,
geotextiles, or fascines.
* * * * *
    Grading means the placement of CCR only to the extent necessary to
create sufficient differences in elevation to support stormwater
drainage.
    Grassy vegetation means vegetation that meets both of the
conditions described in paragraphs (1) and (2) of this definition:
    (1) The vegetation develops shallow roots which both do not
penetrate the slopes or pertinent surrounding areas of the CCR unit to
a substantial depth and do not introduce the potential of internal
erosion or risk of uprooting; and
    (2) The vegetation creates a continuous dense cover that prevents
erosion and deterioration of the surface of the slope or pertinent
surrounding areas, thereby preventing deterioration of the surface.
* * * * *
    Non-groundwater releases mean releases from the CCR unit other than
the releases directly to the groundwater that are detected through the
unit's groundwater monitoring system. Examples of non-groundwater
releases include seepage through the embankment, minor ponding of
seepage at the toe of the embankment of the CCR unit, seepage at the
abutments of the CCR unit, seepage from slopes, ponding at the toe of
the unit, a release of fugitive dust and releases of a ``catastrophic''
nature such as the release of CCR materials from CCR surface
impoundments from the Tennessee Valley Authority's (TVA) Kingston
Fossil Plant in Harriman, TN and the Duke Energy Dan River Steam
Station in Eden, NC.
* * * * *
    Participating state means a state with a state program for control
of CCR that has been approved pursuant to Section 4005 of the Resource
Conservation and Recovery Act.
    Pertinent surrounding areas means all areas of the CCR surface
impoundment or immediately surrounding the CCR surface impoundment that
have the potential to affect the structural stability and condition of
the CCR surface impoundment, including but not limited to the toe of
the downstream slope, the crest of the embankment, abutments, and
unlined spillways.
* * * * *
    Slope protection means measures installed on the slopes or
pertinent surrounding areas of the CCR unit that protect the slope
against wave action, erosion or adverse effects of rapid drawdown.
Slope protection includes grassy vegetation and engineered slope
protection measures.
* * * * *
    State Director means the chief administrative officer of any State
agency operating an approved CCR permit program or the delegated
representative of the State Director. If responsibility is divided
among two or

more State agencies, State Director means the chief administrative
officer of the State agency authorized to perform the particular
function or procedure to which reference is made. On Tribal Lands and
in non-participating States where Congress has specifically provided
appropriations to EPA to administer a CCR permit program, State
Director means the EPA Administrator or their designee.
* * * * *
    Vegetative height means the linear distance between the ground
surface where the vegetation penetrates the ground surface and the
outermost growth point of the vegetation.
* * * * *
    Woody vegetation means vegetation that develops woody trunks, root
balls, or root systems which can penetrate the slopes or pertinent
surrounding areas of the CCR unit to a substantial depth and introduce
the potential of internal erosion or risk of uprooting.
0
3. Section 257.73 is amended by:
0
a. Revising paragraphs (a)(4) and (d)(1)(ii); and
0
b. Removing and reserving paragraph (d)(1)(iv).
    The revisions read as follows:

Sec.  257.73  Structural integrity criteria for existing CCR surface
impoundments.

    (a) * * *
    (4) The slopes and pertinent surrounding areas of the CCR unit must
be designed, constructed, operated, and maintained with one of the
forms of slope protection specified in paragraph (a)(4)(i) of this
section that meets all of the performance standards of paragraph
(a)(4)(ii) of this section.
    (i) Slope protection must consist of one of the following:
    (A) A vegetative cover consisting of grassy vegetation;
    (B) An engineered cover consisting of a single form or combination
of forms of engineered slope protection measures; or
    (C) A combination of the forms of cover specified in paragraphs
(a)(4)(i)(A) or (a)(4)(i)(B) of this section.
    (ii) Any form of cover for slope protection must meet all of the
following performance standards:
    (A) The cover must be installed and maintained on the slopes and
pertinent surrounding areas of the CCR unit;
    (B) The cover must provide protection against surface erosion, wave
action, and adverse effects of rapid drawdown;
    (C) The cover must be maintained to allow for the observation of
and access to the slopes and pertinent surrounding areas during routine
and emergency events;
    (D) Woody vegetation must be removed from the slopes or pertinent
surrounding areas. Any removal of woody vegetation with a diameter
greater than \1/2\ inch must be directed by a person familiar with the
design and operation of the unit and in consideration of the
complexities of removal of a tree or a shrubbery, who must ensure the
removal does not create a risk of destabilizing the unit or otherwise
adversely affect the stability and safety of the CCR unit or personnel
undertaking the removal; and
    (E) The vegetative height of grassy and woody vegetation must not
exceed 12 inches.
* * * * *
    (d) * * *
    (1) * * *
    (ii) Slope protection consistent with the requirements under
paragraph (a)(4) of this section.
* * * * *
0
4. Section 257.74 is amended by:
0
a. Revising paragraphs (a)(4) and (d)(1)(ii); and
0
b. Removing and reserving paragraph (d)(1)(iv).
    The revisions read as follows:

Sec.  257.74  Structural integrity criteria for new CCR surface
impoundments and any lateral expansion of a CCR surface impoundment.

    (a) * * *
    (4) The slopes and pertinent surrounding areas of the CCR unit must
be designed, constructed, operated, and maintained with one of the
forms of slope protection specified in paragraph (a)(4)(i) of this
section that meets all of the performance standards of paragraph
(a)(4)(ii) of this section.
    (i) Slope protection must consist of one of the following:
    (A) A vegetative cover consisting of grassy vegetation;
    (B) An engineered cover consisting of a single form or combination
of forms of engineered slope protection measures; or
    (C) A combination of the forms of cover specified in paragraphs
(a)(4)(i)(A) or (a)(4)(i)(B) of this section.
    (ii) Any form of cover for slope protection must meet all of the
following performance standards:
    (A) The cover must be installed and maintained on the slopes and
pertinent surrounding areas of the CCR unit;
    (B) The cover must provide protection against surface erosion, wave
action, and adverse effects of rapid drawdown;
    (C) The cover must be maintained to allow for the observation of
and access to the slopes and pertinent surrounding areas during routine
and emergency events;
    (D) Woody vegetation must be removed from the slopes or pertinent
surrounding areas. Any removal of woody vegetation with a diameter
greater than \1/2\ inch must be directed by a person familiar with the
design and operation of the unit and in consideration of the
complexities of removal of a tree or a shrubbery, who must ensure the
removal does not create a risk of destabilizing the unit or otherwise
adversely affect the stability and safety of the CCR unit or personnel
undertaking the removal; and
    (E) The vegetative height of grassy and woody vegetation must not
exceed 12 inches.
* * * * *
    (d) * * *
    (1) * * *
* * * * *
    (ii) Slope protection consistent with the requirements under
paragraph (a)(4) of this section.
* * * * *
0
5. Section 257.83 is amended by revising paragraph (b)(5) to read as
follows:

Sec.  257.83  Inspection requirements for CCR surface impoundments.

* * * * *
    (b) * * *
    (5) If a deficiency or release is identified during an inspection,
the owner or operator must remedy the deficiency or release in
accordance with applicable requirements in Sec. Sec.  257.96 through
257.99.
* * * * *
0
6. Section 257.84 is amended by revising paragraph (b)(5) to read as
follows:

Sec.  257.84  Inspection requirements for CCR surface landfills.

* * * * *
    (b) * * *
    (5) If a deficiency or release is identified during an inspection,
the owner or operator must remedy the deficiency or release in
accordance with applicable requirements in Sec. Sec.  257.96 through
257.99.
* * * * *
0
7. Section 257.90 is amended by revising paragraphs (a) and (d) and
adding paragraph (g) to read as follows:

Sec.  257.90  Applicability.

    (a) All CCR landfills, CCR surface impoundments, and lateral
expansions of CCR units are subject to the groundwater monitoring and
corrective action requirements under Sec. Sec.  257.90 through 257.99,
except as provided in paragraph (g) of this section.
* * * * *
    (d) The owner or operator of the CCR unit must comply with all
applicable

requirements in Sec. Sec.  257.96, 257.97, and 257.98, or, if eligible,
must comply with the requirements in Sec.  257.99.
* * * * *
    (g) Suspension of groundwater monitoring requirements. (1) Except
as provided by paragraph (g)(2) of this section, the State Director of
a participating state may suspend for up to ten years the groundwater
monitoring requirements under Sec. Sec.  257.90 through 257.95 for a
CCR unit if the owner or operator provides written documentation that
there is no potential for migration of the constituents listed in
appendices III and IV to this part from that CCR unit to the uppermost
aquifer during the active life of the CCR unit and the post-closure
care period. This demonstration must be certified by a qualified
professional engineer and approved by the State Director, and must be
based upon:
    (i) Site-specific field collected measurements, sampling, and
analysis of physical, chemical, and biological processes affecting
contaminant fate and transport; and
    (ii) Contaminant fate and transport predictions that maximize
contaminant migration and consider impacts on human health and the
environment.
    (2) The owner or operator of the CCR unit may secure an additional
ten years for the suspension of the groundwater monitoring requirements
provided the owner or operator provides written documentation that
there continues to be no potential for migration of the constituents
listed in appendices III and IV to this part. The documentation must be
supported by, at a minimum, the information specified in paragraphs
(g)(1)(i) and (g)(1)(ii) of this section and must be certified by a
qualified professional engineer and approved by the State Director. The
owner or operator must submit the documentation of their re-
demonstration for the state's review and approval of their extension
one year before their groundwater monitoring suspension is due to
expire. If the existing groundwater monitoring extension expires, the
owner or operator must begin groundwater monitoring according to
paragraph (a) of this section within 90 days. The owner or operator may
obtain additional ten-year groundwater monitoring suspensions provided
the owner or operator continues to make the written demonstration. The
owner or operator must place each completed demonstration, if more than
one ten-year suspension period is sought, in the facility's operating
record.
0
8. Section 257.95 is amended by revising paragraph (h)(2) and adding
paragraph (j) to read as follows:

Sec.  257.95  Assessment monitoring program.

* * * * *
    (h) * * *
    (2) For constituents for which an MCL has not been established, the
background concentration for the constituent established from wells in
accordance with Sec.  257.91, except as provided by paragraph (j) of
this section; or
* * * * *
    (j) The State Director of a participating state may establish an
alternative groundwater protection standard for constituents listed in
appendix IV to this part for which MCLs have not been established.
    (1) The alternative groundwater protection standards must be
appropriate health-based levels that are protective of potential
receptors (both human and ecological) and satisfy all of the following
criteria:
    (i) The alternative groundwater protection standard is at a level
derived in a manner consistent with EPA guidelines for assessing the
health risks of environmental pollutants, including ``Supplementary
Guidance for Conducting Health Risk Assessment of Chemical Mixtures'',
``Guidelines for Developmental Toxicity Risk Assessment'', and
``Reference Dose, (RfD): Description and Use in Health Risk
Assessments'' (incorporated by reference);
    (ii) The alternative groundwater protection standard is at a level
based on scientifically valid studies conducted in accordance with the
Toxic Substances Control Act Good Laboratory Practice Standards (40 CFR
part 792) or equivalent; and
    (iii) For systemic toxicants, the level represents a concentration
to which the human population could be exposed to on a daily basis that
is likely to be without appreciable risk of deleterious effects during
a lifetime; this must be the level that ensures a Hazard Quotient no
greater than 1. For purposes of this subpart, systemic toxicants are
toxic chemicals that cause effects other than cancer.
    (2) In establishing alternative groundwater protection standards
under paragraph (j)(1) of this section, the State Director may consider
the following:
    (i) Multiple contaminants in the groundwater;
    (ii) Exposure threats to sensitive environmental receptors; and
    (iii) Other site-specific exposure or potential exposure to
groundwater.
    (3) The owner or operator of the CCR unit must document in the
annual groundwater monitoring and corrective action report required by
Sec.  257.90(e) or Sec.  257.100(e)(5)(ii) the constituent(s) and
level(s) for which an alternative groundwater protection standard has
been established by the State Director.
0
9. Section 257.97 is amended by adding paragraphs (f) and (g) to read
as follows:

Sec.  257.97  Selection of remedy.

* * * * *
    (f) The State Director of a participating state may determine that
remediation of a release of a constituent listed in appendix IV to this
part from a CCR unit is not necessary if the owner or operator
demonstrates to the satisfaction of the State Director that:
    (1) The groundwater is additionally contaminated by substances that
have originated from a source other than a CCR unit and those
substances are present in concentrations such that cleanup of the
release from the CCR unit would provide no significant reduction in
risk to actual or potential receptors; or
    (2) The constituent(s) is present in groundwater that:
    (i) Is not currently or reasonably expected to be a source of
drinking water; and
    (ii) Is not hydraulically connected with waters to which the
constituent(s) is migrating or are likely to migrate in a
concentration(s) that would exceed the groundwater protection standards
established under Sec.  257.95(h) or (i); or
    (3) Remediation of the release(s) is technically impracticable; or
    (4) Remediation results in unacceptable cross-media impacts.
    (g) A determination by the Director of approved participating state
pursuant to paragraph (f) of this section shall not affect the
requirement under Sec.  257.90(d) and Sec.  257.97(b) for the owner or
operator to undertake source control measures or other measures
(including closure if triggered) that may be necessary to eliminate or
minimize further releases to the groundwater, to prevent exposure to
the groundwater, or to remediate the groundwater to concentrations that
are technically feasible and significantly reduce threats to human
health or the environment.
0
10. Section 257.98 is amended by revising paragraph (c) to read as
follows:

Sec.  257.98  Implementation of the corrective action program.

* * * * *
    (c) Remedies selected pursuant to Sec.  257.97 shall be considered
complete when:

    (1) The owner or operator of the CCR unit demonstrates compliance
with the groundwater protection standards established under Sec.
257.95(h) has been achieved at all points within the plume of
contamination that lie beyond the groundwater monitoring well system
established under Sec.  257.91;
    (2) Except as provided by paragraph (c)(4) of this section,
compliance with the groundwater protection standards established under
Sec.  257.95(h) has been achieved by demonstrating that concentrations
of constituents listed in appendix IV to this part have not exceeded
the groundwater protection standard(s) for a period of three
consecutive years using the statistical procedures and performance
standards in Sec.  257.93(f) and (g); and
    (3) All actions required to complete the remedy have been
satisfied.
    (4) The Director of a participating state may specify an
alternative length of time to that specified in paragraph (c)(2) of
this section during which the owner or operator must demonstrate that
concentrations of constituents listed in appendix IV to this part have
not exceeded the groundwater protection standard(s) taking into
consideration:
    (i) Extent and concentration of the release(s);
    (ii) Behavior characteristics of the constituents in the
groundwater;
    (iii) Accuracy of monitoring or modeling techniques, including any
seasonal, meteorological, or other environmental variabilities that may
affect the accuracy; and
    (iv) Characteristics of the groundwater.
* * * * *
0
11. Add Sec.  257.99 to read as follows:

Sec.  257.99  Corrective action procedures to remedy eligible non-
groundwater releases.

    (a) General. This section specifies the corrective action
requirements that apply to non-groundwater releases from CCR units that
can be completely remediated within 180 days from the detection of the
release. A release is completely remediated when either a qualified
professional engineer or the permitting authority of a participating
state completes the certification required in subsection (c)(2) of this
section. If the owner or operator determines, at any time, that the
release will not be completely remediated within this 180-day
timeframe, the owner or operator must comply with all additional
procedural requirements specified in Sec. Sec.  257.96, 257.97, and
257.98.
    (b) Corrective action requirements. Upon detection of a non-
groundwater release from a CCR unit, the owner or operator must comply
with all of the following requirements:
    (1) Meet the requirement in Sec.  257.90(d) to ``immediately take
all necessary measures to control the source(s) of releases so as to
reduce or eliminate, to the maximum extent feasible, further releases
of contaminants into the environment;''
    (2)(i) Determine the corrective measures that will meet the
substantive standards in Sec. Sec.  257.96(a) to prevent further
releases, to remediate any releases and to restore the affected area to
original conditions; and
    (ii) Analyze the effectiveness of potential corrective measures in
meeting all of the requirements and objectives of the remedy as
described in Sec.  257.96(c);
    (3) Select the corrective action that will remedy the non-
groundwater release, taking into account, at a minimum, the results of
the assessment in paragraph (b)(2)(ii) of this section and the factors
specified in Sec.  257.97(c); and
    (4) Remediate the non-groundwater release to meet the standards
specified in Sec.  257.97(b)(1), (3), (4), and (5).
    (5) Complete remedy within 180 days of the date of discovery of the
release.
    (c) Required notices and reports. An owner or operator of a CCR
unit that complies with the requirements of this section to remediate a
non-groundwater release is responsible for ensuring that the notices
and reports specified in paragraphs (c)(1) through (c)(3) of this
section are completed in accordance with this section. All required
notices and reports must be signed by the owner or operator.
    (1) Within 15 days of discovering a non-groundwater release, the
owner or operator must prepare a notification of discovery of a non-
groundwater release. The owner or operator has completed the
notification when it has been placed in the facility's operating record
as required by Sec.  257.105(h)(15).
    (2) Within 15 days of completing the analysis of the effectiveness
of potential corrective measures as required by paragraph (b)(2)(ii) of
this section, place the completed analysis in the facility's operating
record.
    (3) Within 30 days of completion of a corrective action of a non-
groundwater release, the owner or operator must prepare a report
documenting the completion of the corrective action. The report must,
at a minimum, describe the nature and extent of the non-groundwater
release, the CCR unit(s) responsible for the non-groundwater release,
and how the remedy selected achieves the corrective action requirements
specified in paragraph (b) of this section. The notification must
include a certification by a qualified professional engineer that the
corrective action has been completed in accordance with the
requirements of paragraph (b) of this section. The owner or operator
has completed the notification when it has been placed in the
facility's operating record as required by Sec.  257.105(h)(16).
    (d) The owner or operator of the CCR unit must comply with the
recordkeeping requirements specified in Sec.  257.105(h), the
notification requirements specified in Sec.  257.106(h), and the
internet requirements specified in Sec.  257.107(h).
0
12. Section 257.102 is amended by adding paragraph (d)(4) to read as
follows:

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

* * * * *
    (d) * * *
    (4) Use of CCR in Design and Construction of Final Cover System.
(i) This paragraph specifies the allowable uses of CCR in the closure
of CCR units closing pursuant to Sec.  257.101. Notwithstanding the
prohibition on further placement in Sec.  257.101, CCR may be placed in
such units but only for the purposes of grading and contouring in the
design and construction of the final cover system, based either on:
    (A) A determination by the Director of a participating state that
the criteria in paragraph (d)(4)(ii) of this section have been met; or
    (B) The certification by a qualified professional engineer that the
criteria in (d)(4)(ii) of this section have been met, as required in
paragraph (d)(4)(iii) of this section.
    (ii) Use of CCR in Design and Construction of Final Cover System
Requirements.
    (A) The owner or operator of a CCR unit subject to Sec.  257.101
may continue to place CCR in the unit after initiating closure in order
to construct the final cover system required under paragraph (d)(3) of
this section but only for the following activities:
    (1) Grading; and
    (2) Contouring.
    (B) The owner or operator of a CCR unit must meet all of the
following criteria when placing CCR within a CCR unit for the purposes
of grading or contouring:
    (1) The CCR placed for construction of the final cover system must
have been generated at the facility and be located at the facility at
the time closure was initiated;
    (2)(i) For incised CCR surface impoundments the CCR must be placed
entirely above the highest elevation of

the surrounding natural ground surface where the CCR surface
impoundment was constructed;
    (ii) For all other CCR units, CCR must be placed entirely above the
highest elevation of CCR in the unit, following dewatering and
stabilization as required by Sec.  257.102(d)(2);
    (3) The CCR must not be placed outside the plane extending
vertically from the line formed by the intersection of the crest of the
CCR surface impoundment and the upstream slope of the CCR surface
impoundment; and
    (4) The final cover system must be constructed with either:
    (i) A slope not steeper than 5% grade after allowance for
settlement; or
    (ii) At a steeper grade, if the Director of a participating state
determines that the steeper slope is necessary based on conditions at
the site, to facilitate run-off and minimize erosion, and that side
slopes are evaluated for erosion potential based on a stability
analysis to evaluate possible erosion potential. The stability
analysis, at a minimum, must evaluate the site geology; characterize
soil shear strength; construct a slope stability model; establish
groundwater and seepage conditions, if any; select loading conditions;
locate critical failure surface; and iterate until minimum factor of
safety is achieved.
    (iii) If required by paragraph (d)(4)(i)(B) of this section, the
owner or operator of the CCR unit must also include in the notification
required by Sec.  257.102(h) a certification by a qualified
professional that the CCR unit was closed in accordance with the
requirements of paragraph (d)(4) of this section.
* * * * *
0
13. Section 257.103 is amended by:
0
a. Revising Sec.  257.103 introductory text; and
0
b. Redesignating paragraphs (b), (c), and (d) as (c), (e), and (f); and
adding new paragraphs (b) and (d).
    The revisions and additions read as follows:

Sec.  257.103  Alternative closure requirements.

    The owner or operator of a CCR landfill, CCR surface impoundment,
or any lateral expansion of a CCR unit that is subject to closure
pursuant to Sec.  257.101(a), (b)(1), or (d) may continue to receive
CCR and/or non-CCR wastestreams in the unit provided the owner or
operator meets the requirements of either paragraph (a), (b), (c) or
(d) of this section.
* * * * *
    (b) No Alternative capacity for non-CCR wastestreams. (1)
Notwithstanding the provisions of Sec.  257.101(a), (b)(1), or (d), a
CCR unit may continue to receive non-CCR wastestreams if the owner or
operator of the CCR unit certifies that the wastestreams must continue
to be managed in that CCR unit due to the absence of alternative
capacity both on-site and off-site the facility. For these non-CCR
wastestsreams, capacity means the capacity of impoundments, tanks, and
other conveyances to manage daily flows currently handled by the unit
that is closing pursuant to Sec.  257.101(a) or (b)(1), or (d). To
qualify under this paragraph (b)(1), the owner or operator of the CCR
unit must document that all of the following conditions have been met
for each non-CCR wastestream that will continue to be received by the
CCR unit:
    (i) No alternative disposal capacity is available. An increase in
costs or the inconvenience of existing capacity is not sufficient to
support qualification under this section;
    (ii) The owner or operator has made, and continues to make, efforts
to obtain additional capacity. Qualification under this subsection
requires that efforts to obtain additional capacity were made at the
earliest date that an owner or operator knew, or had reason to know,
that such a unit may become subject to closure under Sec.  257.101(a),
(b)(1), or (d). Qualification under this subsection lasts only as long
as no alternative capacity is available. Once alternative capacity is
identified, the owner or operator must arrange to use such capacity as
soon as feasible;
    (iii) The owner or operator must certify that the facility
generating any wastestream that continues to be placed into a CCR unit
pursuant to this section would need to cease generating power and is
located in or regularly provides the majority of generated electricity
to, one of the following three North American Electric Reliability
Corporation regions and sub-regions: the Midcontinent Independent
System Operator, the Southeastern Electric Reliability Council-East,
and/or the Southeastern Electric Reliability Council-North;
    (iv) The owner or operator must remain in compliance with all other
requirements of this subpart, including the requirement to conduct any
necessary corrective action; and
    (v) The owner or operator must prepare an annual progress report
documenting the continued lack of alternative capacity and the progress
towards the development of alternative capacity for the given
wastestream.
    (2) Once alternative capacity is available for a given wastestream,
the CCR unit must cease receiving that wastestream, and in the case
that alternate capacity has been found for all wastestreams, the
facility must initiate closure of the CCR unit following the timeframes
in Sec.  257.102(e) and (f).
    (3) If no alternative capacity is identified within five years
after the initial certification as required under (b)(1) of this
section, the CCR unit must cease receiving all wastestreams and close
in accordance with the timeframes in Sec.  257.102(e) and (f).
* * * * *
    (d) Permanent cessation of a coal-fired boiler(s) by a date
certain. (1) Notwithstanding the provisions of Sec.  257.101(a),
(b)(1), and (d), a CCR unit may continue to receive non-CCR
wastestreams if the owner or operator certifies that the facility will
cease operation of the coal-fired boilers within the timeframes
specified in paragraphs (d)(2) and (3) of this section, but in the
interim period (prior to closure of the coal-fired boiler), the
facility must continue to use the CCR unit due to the absence of
alternative capacity. For wastewaters capacity means the capacity of
impoundments, tanks, and other units to manage daily flows currently
handled by the unit closing pursuant to Sec.  257.101(a) or (b)(1). To
qualify under this paragraph (d)(1), the owner or operator of the CCR
unit must document that all of the following conditions have been met
for each wastestream that will continue to be received by the CCR unit:
    (i) No alternative capacity is available. An increase in costs or
the inconvenience of existing capacity is not sufficient to support
qualification under this section.
    (ii) The owner or operator must certify that the facility is
located in or regularly provides the majority of generated electricity
to one of the following three North American Electric Reliability
Corporation regions and sub-regions: The Midcontinent Independent
System Operator, the Southeastern Electric Reliability Council-East,
and/or the Southeastern Electric Reliability Council-North.
    (iii) The owner or operator must remain in compliance with all
other requirements of this subpart, including the requirement to
conduct any necessary corrective action; and
    (iv) The owner or operator must prepare an annual progress report
documenting the continued lack of alternative capacity and the progress
towards the closure of the coal-fired boiler.
    (2) For a CCR surface impoundment that is 40 acres or smaller, the
coal-fired boiler must cease operation and the CCR surface impoundment
must have

completed closure no later than October 17, 2023.
    (3) For a CCR surface impoundment that is larger than 40 acres, the
coal-fired boiler must cease operation, and the CCR surface impoundment
must complete closure no later than October 17, 2028.
* * * * *
0
14. Section 257.104 is amended by revising paragraph (c) to read as
follows:

Sec.  257.104  Post-closure care requirements.

* * * * *
    (c) Post-closure care period. (1) Except as provided by paragraphs
(c)(2) and (3) of this section, the owner or operator of the CCR unit
must conduct post-closure care for 30 years.
    (2) If at the end of the post-closure care period the owner or
operator of the CCR unit is operating under assessment monitoring in
accordance with Sec.  257.95, the owner or operator must continue to
conduct post-closure care until the owner or operator returns to
detection monitoring in accordance with Sec.  257.95.
    (3)(i) The Director of a participating state may establish an
alternate post-closure period upon a determination that the alternate
period is sufficient to protect human health and the environment.
    (ii) To reduce the post closure care period, the Director must
ensure that the post-closure care period is long enough to establish
settlement behavior and to detect to wear-in defects in the cover
system. At a minimum, the Director must consider the type of cover
placed on the unit (e.g., geosynthetic clay liner) and the placement of
the groundwater monitoring wells with respect to the waste management
units and the groundwater table.
    (iii) A determination that a reduced post-closure care period is
warranted does not affect the obligation to comply with paragraph (b)
of this section.
* * * * *
0
15. Section 257.105 is amended by adding paragraphs (h)(14) through
(h)(16) and paragraph (i)(14) to read as follows:

Sec.  257.105  Recordkeeping requirements.

* * * * *
    (h) * * *
    (14) The demonstration, including long-term performance data,
supporting the suspension of groundwater monitoring requirements as
required by Sec.  257.90(g).
    (15) The notification of discovery of a non-groundwater release as
required by Sec.  257.99(c)(1).
    (16) The report documenting the completion of the corrective action
as required by Sec.  257.99(c)(2).
    (i) * * *
    (14) The demonstration, including long-term performance data
supporting the reduced post-closure care period as required by Sec.
257.104(c)(3).
* * * * *
0
16. Section 257.106 is amended by adding paragraphs (h)(11) through
(h)(13) and paragraph (i)(14) to read as follows:

Sec.  257.106  Notification requirements.

* * * * *
    (h) * * *
    (11) Provide the demonstration supporting the suspension of
groundwater monitoring requirements specified under Sec.
257.105(h)(14).
    (12) Provide notification of discovery of a non-groundwater release
specified under Sec.  257.105(h)(15).
    (13) Provide notification of the availability of the report
documenting the completion of the corrective action specified under
Sec.  257.105(h)(16).
    (i) * * *
    (14) Provide the demonstration supporting the reduced post-closure
care period specified under Sec.  257.105(i)(14).
* * * * *
0
17. Section 257.107 is amended by adding paragraphs (h)(11) through
(h)(13) and adding paragraph (i)(14) to read as follows:

Sec.  257.107  Publicly accessible internet site requirements.

* * * * *
    (h) * * *
    (11) The demonstration supporting the suspension of groundwater
monitoring requirements specified under Sec.  257.105(h)(14).
    (12) The notification of discovery of a non-groundwater release
specified under Sec.  257.105(h)(15).
    (13) The report documenting the completion of the corrective action
specified under Sec.  257.105(h)(16).
    (i) * * *
    (14) The demonstration supporting the reduced post-closure care
period specified under Sec.  257.105(i)(14).
* * * * *
0
18. Revise Appendix IV to part 257 to read as follows:

Appendix IV to Part 257--Constituents for Assessment Monitoring

                             Common Name \1\
------------------------------------------------------------------------

-------------------------------------------------------------------------
Antimony
------------------------------------------------------------------------
Arsenic
------------------------------------------------------------------------
Barium
------------------------------------------------------------------------
Beryllium
------------------------------------------------------------------------
Boron
------------------------------------------------------------------------
Cadmium
------------------------------------------------------------------------
Chromium
------------------------------------------------------------------------
Cobalt
------------------------------------------------------------------------
Fluoride
------------------------------------------------------------------------
Lead
------------------------------------------------------------------------
Lithium
------------------------------------------------------------------------
Mercury
------------------------------------------------------------------------
Molybdenum
------------------------------------------------------------------------
Selenium
------------------------------------------------------------------------
Thallium
------------------------------------------------------------------------
Radium 226 and 228 combined
------------------------------------------------------------------------
\1\ Common names are those widely used in government regulations,
  scientific publications, and commerce; synonyms exist for many
  chemicals.

[FR Doc. 2018-04941 Filed 3-14-18; 8:45 am]
 BILLING CODE 6560-50-P