care period shall be no less than annual. As noted, the owner or
operator will bear the burden of justifying an alternate frequency
under this regulation, and in any court proceeding brought to enforce
these requirements. This means that any uncertainty or lack of
information will be weighed against the entity seeking to justify the
alternate frequency.
    Consistent with the proposed rule, if the owner or operator
determines that there is a statistically significant increase (SSI)
over background for one or more of the parameters listed in appendix
III at any monitoring well at the waste boundary, the owner or operator
must place a notice in the operating record and on the facility's
internet site indicating which parameters have shown statistically
significant changes from background levels and notify the State
Director.
    The facility must also then establish an assessment monitoring
program and begin monitoring within 90 days. The owner or operator has
the opportunity to demonstrate that a source other than the CCR unit
caused the statistically significant increase or that the statistically
significant increase resulted from error in sampling, analysis,
statistical evaluation or a natural variation in groundwater quality.
Within 90 days, the owner or operator must prepare a report documenting
this demonstration which must then be certified by a qualified
professional engineer verifying the accuracy of the information in the
report. If a successful demonstration is made within 90 days, the owner
or operator may continue detection monitoring. If a successful
demonstration is not made within 90 days, the owner or operator must
initiate assessment monitoring.
    Commenters raised concern that 90 days would not be sufficient to
complete all of the activities necessary to determine whether the
detection of an SSI was from another source than the CCR unit or was
based on inaccurate results. The Agency recognizes that in some
circumstances it could take more than 90 days to resample and have
laboratories conduct new analyses, or to conduct field investigations
to determine that another source is causing the contamination. As a
result, Sec.  257.94(e)(3) does not place an ultimate time limit for
owners and operators to complete the demonstration. However, if after
90 days the owner or operator has not made a successful demonstration,
(s)he must begin an assessment monitoring program. At this stage, there
is evidence to indicate that a release has occurred from the CCR unit,
and while EPA agrees that the facility may want to confirm that the
information is accurate, it is critical that the facility not delay
indefinitely the more targeted monitoring to determine whether a
constituent of concern is contaminating groundwater. It would not be
consistent with the statutory standard to allow a facility unlimited
time to delay taking reasonable steps to assess, and if necessary,
address potential contamination by continuing to resample until they
obtain a ``better'' answer. Moreover, initiation of an assessment
monitoring program does not involve an irretrievable commitment of
resources or even a significant investment by the facility, but only
requires the facility to begin more targeted sampling for constituents
of concern. This represents a reasonable first step to address a
potential threat to groundwater. This requirement is also in the MSWLF
part 258 regulations. For more information see 56 FR 51078 (October 9,
1991).
    Subsequent to initiating the assessment monitoring program, if an
owner or operator demonstrates that the statistically significant
increase resulted from an error in sampling, analysis, statistical
evaluation, or natural variation in groundwater quality, or was caused
by a source other than the CCR unit, the owner or operator may cease
assessment monitoring and return to detection monitoring. If the
demonstration is successful, the owner or operator must have the
demonstration certified by a qualified professional engineer, and is
required by Sec.  257.94(e)(3) to place a notice in the operating
record, and on publicly accessible Internet site and send a copy of the
report to the State Director.
5. Assessment Monitoring Program
    EPA is adopting an assessment monitoring program that is largely
identical to the program laid out in the proposal. However, as
discussed in more detail below, some revisions have been made; some
were made in response to comments, but most are conforming changes made
to be consistent with changes adopted in other provisions, such as the
detection monitoring program described previously.
    Consistent with the proposed rule, if any of the detection
monitoring parameters are detected at a statistically significant level
over the established background concentrations, the owner or operator
must proceed to the next step, assessment monitoring. Assessment
monitoring requires annual sampling and analysis for the full list of
constituents included in appendix IV. The number and frequency of
samples required for assessment monitoring are the same as those
established for detection monitoring. See discussion above in 3.
Sampling and Analysis Requirements.
    EPA has also revised the list of constituents in appendix IV by
deleting the following constituents and parameters: Aluminum, boron,
chloride, copper, iron, manganese, pH, sulfate, sulfide, and TDS; and
adding the following constituents: Cobalt, lithium, and radium 226 and
228 combined. The following constituents and parameters are being
removed from appendix IV because they are on appendix III and therefore
will continue to be monitored throughout assessment monitoring: Boron,
chloride, pH, sulfate and TDS. Although fluoride is on appendix III, we
are also retaining it on appendix IV because it does have an MCL and
was found to pose risks in the 2014 risk assessment, and therefore is
appropriately considered to be a constituent that is relevant for
purposes of corrective action. Aluminum, copper, iron, manganese, and
sulfide have been removed because they lack maximum contaminant levels
(MCLs) and were not shown to be constituents of concern based on either
the risk assessment conducted for this rule or the damage cases (see
Units X and XI of this document). Cobalt has been added to appendix IV
because cobalt was found to be a risk driver in the 2014 risk
assessment, based on certain waste management disposal practices that
lead to highly acidic wastes conditions. Lithium is being added to
appendix IV because it has been detected in several proven and
potential damage cases at levels exceeding EPA's Regional Screening
Level (RSL) of soil to groundwater and has been determined as
potentially toxic if consumed concurrently with certain drug
types.\117\ Radium 226 and 228 combined (the sum of the radioactive
isotopes radium-226 and radium-228) is being added because there is
evidence from several damage cases of exceedances of gross alpha,
indicating that radium from the disposal of CCR may be problematic.
Appendix IV now contains antimony, arsenic, barium, beryllium, cadmium,
chromium, cobalt, fluoride, lead, lithium, mercury, molybdenum,

selenium, thallium and radium 226 and 228 combined.
---------------------------------------------------------------------------

    \117\ EPA's Regional Screening Level (RSL) Soil to Groundwater
Supporting Table (TR = 1E-6, HQ = 1) May 2014/Mid-atlantic Risk
assessment: http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/Generic_Tables/index.htm; and Health
Consultation: Chesapeake ATGAS 2H Well Site Leroy Hill Road, Leroy,
Leroy Township, Bradford County, Pennsylvania, October 29, 2013.
U.S. Department of Health and Human Services, Agency for Toxic
Substances and Disease Registry Division of Community Health
Investigations Atlanta, Georgia. http://www.atsdr.cdc.gov/.
---------------------------------------------------------------------------

    If any appendix IV constituents are detected in any appendix IV
analyses, the owner or operator must notify the State Director and
continue to monitor, at least semiannually, for both the specific
constituents in appendix IV that were detected and all parameters in
appendix III. EPA has decided to also include a provision to allow an
alternative sampling frequency if there is not adequate groundwater to
flow to sample wells semiannually, consistent with the revised
provision adopted for the detection monitoring program. If the owner or
operator demonstrates at any time during assessment monitoring that all
of the detected appendix III and IV constituents are at or below
background values for two consecutive sampling events, (s)he must
notify the state and may return to detection monitoring. In general,
EPA expects that appendix III constituents are unlikely to remain
elevated once measures have been taken to address the release of the
detected appendix IV constituents. But should appendix III constituent
levels remain elevated, detection monitoring continues to be necessary
to determine whether another source of contamination is present.
    After obtaining the sampling results the owner or operator must
place a notice in the operating record and on the facility's internet
site indicating which appendix IV constituents have been detected and
notify the State Director. Within 90 days and on at least a semiannual
basis thereafter, the owner or operator must resample all wells,
conduct analyses for all parameters in appendix III and for those
constituents in appendix IV that were detected in the initial
assessment monitoring sampling event. The results of this resampling
must be placed in the owner or operator's operating record, as well as
its publicly accessible internet site. The results of the resampling
must also be sent to the State Director. These provisions have been
adopted without change from the proposal.
    For each appendix IV constituent that is detected, a groundwater
protection standard must be set. The groundwater protection standards
must be the MCL or the background concentration level for the detected
constituent, whichever is higher. If there is no MCL promulgated for a
detected constituent, then the groundwater protection standard must be
set at background. The proposed rule would have allowed the owner or
operator to establish an alternative groundwater protection standard
for constituents for which MCLs have not been established provided that
the alternative groundwater protection standard has been certified by
an independent registered professional engineer and the state has been
notified that the alternative groundwater protection standard has been
placed in the operating record and on the owner's or operator's
publicly accessible internet site. This provision had been adopted from
the part 258 regulations, but was determined to be inappropriate in a
self-implementing rule, as it was unlikely that a facility would have
the scientific expertise necessary to conduct a risk assessment, and
was too susceptible to potential abuse. Additionally, numerous comments
were received suggesting that only those constituents with MCLs be
included in appendix IV. The commenters were concerned that only MCLs
are enforceable. With the exception of cobalt, lead, lithium and
molybdenum (included on appendix IV because of their relevance in the
risk assessment and damage cases), all appendix IV constituents have an
MCL. In the proposed rule, as stated above, owner or operators were
allowed to establish certain types of alternative groundwater
protection standards. In the final rule, if a constituent has no MCL
(i.e., cobalt, lead, lithium and molybdenum), their groundwater
protection standards will be their background levels. These background
standards are sufficiently precise that they are enforceable.
    The owner or operator must compare the levels of any detected
appendix IV constituents to the appropriate groundwater protection
standard. If the concentrations of all appendix IV constituents are
shown to be at or below background values for two consecutive sampling
events using the statistical procedures required by Sec.  257.93, the
owner or operator of the CCR disposal facility must place that
information in the operating record and on the facility's publicly
accessible internet site and notify the State Director. The owner or
operator may then return to detection monitoring.
    If the concentrations of any appendix III or IV constituents are
above background values, but all concentrations are determined to be
below the groundwater protection standard using the statistical
procedures required by this rule, the owner or operator must continue
assessment monitoring program.
    If, however, the monitoring indicates a statistically significant
increase for any appendix IV constituent over the groundwater
protection standard, the owner or operator is required to notify the
State Director and local officials of this finding and place a notice
in the operating record and on the owner or operator's publicly
accessible internet site.
    The owner or operator also must characterize the nature and extent
of the release. As part of characterizing the nature and extent of the
release, the owner or operator must install additional wells, as
necessary to define the contaminant plume(s) and collect data on the
nature and estimated quantity of the material released. Adequate
characterization of the release is critical in designing and
effectively implementing a protective corrective action program if
groundwater remediation is necessary. The purpose of these additional
wells is to delineate the contaminant plume boundary and to eventually
demonstrate the effectiveness of corrective action in meeting the
groundwater protection standard.
    Because the requirements for additional monitoring are entirely
specific to the site conditions and the size and nature of the release,
the Agency is not able to set requirements that precisely specify the
location or the number of additional wells that must be installed.
Instead EPA has adopted an approach that corresponds to the approach to
designing the original groundwater monitoring system under Sec.
257.91. The regulations establish a general performance standard
(``install additional wells as necessary to define the contaminant
plume'') and specify a true minimum of installing at least one well at
the facility boundary in the direction of contaminant migration in
order to ascertain whether the contaminants have migrated past the
facility boundary. The regulations also establish a rebuttable
presumption that this minimum is insufficient, requiring the owner or
operator to justify a decision to install only this minimum. The
requirement to justify the decision to only install the minimum number
of additional wells is a revision from the proposal that has been
adopted to be consistent with the Agency's overall approach to
developing an effective groundwater monitoring system.
    The Agency has also added some clarification to the proposed
requirement to characterize the nature and extent of the release, by
requiring the owner or operator to collect data on the nature and
estimated quantity of material released, including specific information
on the constituents listed in appendix IV and the levels at which they
are present in the material released. This information will be
necessary to help the owner or operator characterize the release and
assist in ultimately deciding on a remedy.

    If contamination has migrated off-site, the owner or operator must
notify individuals who own land or reside on land overlying the plume.
    In addition to characterizing the nature and extent of the release,
the owner or operator must initiate an assessment of corrective
measures within 90 days of finding a statistically significant increase
over background concentrations, and select the appropriate remedy.
During this phase, the owner or operator is required to continue at
least semiannual monitoring (or an alternative frequency, no less than
annually) for all appendix III constituents and for those appendix IV
constituents exceeding the groundwater protection standard. To be
consistent with the provisions in detection monitoring, EPA has
included a provision that would allow the owner or operator to
demonstrate that a source other than their CCR unit caused the
contamination or that the statistically significant increase above
groundwater protection standards resulted from error in sampling,
analysis, statistical evaluation, or natural variation in groundwater
quality. This alternative option will not delay compliance with the
next phase of the groundwater monitoring and corrective action program.
Thus, until such a demonstration is made, the owner or operator must
comply with the other requirements of this section, including
initiating the assessment of corrective measures. At this stage, the
evidence that the CCR unit is leaking is stronger, and the owner or
operator has previously had the opportunity to demonstrate that the
finding was made in error under the detection monitoring program, so no
further delay in initiating measures to address any groundwater
contamination is warranted.
    Another change since the proposal is that in addition to complying
with all of the corrective action requirements--i.e., initiating an
assessment of corrective measures, followed by selection of a remedy
and implementation of a corrective action program--if the unit is an
unlined surface impoundment, it must either retrofit or initiate
closure. Further, where the facility has chosen to install a multi-unit
groundwater monitoring system, the detection of an SSI of an appendix
IV constituent would trigger the corrective action and closure (or
retrofit) of all of the unlined surface impoundments covered by that
monitoring system, as there will be no way to isolate a particular
unlined unit as the source of the contamination. These requirements are
discussed in more detail in the Closure section.
6. Assessment of Corrective Measures
    This section of the regulations also largely mirrors the analogous
provisions in the proposed rule. EPA added some language to reflect
that this section is not limited to the remediation of groundwater from
a leaking CCR unit but will also apply to contamination caused by any
kind of release from a CCR unit. EPA also made some minor revisions in
response to comments, and some editorial changes to conform this
provision to changes made in other sections of the rule.
    Consistent with the proposal, Sec.  257.96(a) specifies that the
assessment of corrective measures must be initiated within 90 days of
detecting a statistically significant increase of any of the
constituents listed in appendix IV, at a level exceeding the
groundwater protection standard(s), or of otherwise documenting a
release of contaminants from the CCR unit. The regulation also requires
the assessment of corrective measures to be completed in 90 days of
such a finding, but in response to comments, EPA is adopting a
provision that will allow for a single 60 day extension. Multiple
commenters argued that 90 days was not adequate to complete the
assessment of corrective measures. Commenters stated that for
situations with complex hydrogeology, additional studies and sampling
may be required in order to assess potential contributing offsite
sources, background levels, and possible remedies. They stated that
identification of remedy alternatives, collection and analysis of data
used to evaluate remedy alternatives, and discussions with vendors/
contractors regarding availability of labor and materials are all
critical steps in the remedy selection process. As explained in the
``Technical Manual Solid Waste Disposal Facility Criteria,'' EPA530-R-
93-017, USEPA, November, 1993, Chapter 5, Subpart E, Ground-Water
Monitoring and Corrective Action, the owner or operator will need to:
(1) Identify and remediate the source of contamination; and (2)
identify and remediate the known contamination. The factors that must
be considered in assessing corrective measures include source
evaluation, plume delineation, groundwater assessment and source
control. Based on the comments received, as well as the Agency's own
experience, EPA recognizes that there may be complex situations that
require more time to develop a careful and well-thought out corrective
measures assessment. Therefore, the final rule has been modified to
allow up to an additional 60 days to complete the assessment of
corrective measures, provided that a qualified professional engineer
certifies that the additional time is necessary. The initial 90 days
plus the additional 60 days, which is within the range of time
suggested by the commenters, would provide the owner or operator up to
150 days to complete the corrective measures assessment, which EPA
expects will be sufficient. The certification must be placed in the
operating record, on the owner's or operator's publicly accessible
internet site and submitted to the proper state official.
    The rule requires the owner or operator to assess the effectiveness
of potential remedies in meeting the objectives of Sec.  257.97 by
addressing at least: (1) Performance, reliability, ease of
implementation and potential impacts; (2) time requirements; and (3)
institutional requirements. The proposed rule also included
consideration of the costs of remedy implementation. However, that
language came directly from the MSWLF rule in part 258. Because
Congress did not authorize the consideration of costs in establishing
minimum national standards under RCRA section 4004(a), we have removed
this factor. In evaluating the performance, reliability, ease of
implementation, and potential impacts of each remedy, the owner or
operator should evaluate whether specific remedial technologies are
appropriate to the problem and the ability of those technologies to
achieve the groundwater protection standards. Analysis of a remedy's
reliability should include an assessment of the effectiveness of the
remedy in controlling the source of the release and its long-term
reliability. Source control measures need to be evaluated to limit the
migration of the plume, and to ensure an effective remedy. The
regulation does not limit the definition of source control to exclude
any specific type of measure to achieve this. Remedies must control the
source of the contamination to reduce or eliminate further releases by
identifying and locating the cause of the release. Source control
measures may include the following: Modifying the operational
procedures (e.g., banning waste disposal); undertaking more extensive
and effective maintenance activities (e.g., excavate waste to repair a
liner failure); or, in extreme cases, excavation of deposited wastes
for treatment and/or offsite disposal. Construction and operation
requirements also should be evaluated. The analysis of the timing of
potential remedies should include an evaluation of construction, start-
up, and

completion time. Timing is particularly important if contamination has
migrated off-site. Institutional requirements such as local permit or
public health requirements may affect implementation of the remedies
evaluated and should be assessed by the owner or operator.
    The proposed rule included a provision that would allow an owner or
operator to determine that compliance cannot be reasonably achieved
with any currently available methods. This has been deleted from the
final rule. The Agency determined that without state oversight or a
permitting program, that provision was potentially subject to abuse and
thus, inappropriate to include in a self-implementing rule.
    As part of evaluating potential remedies, the owner or operator
must hold a public meeting to discuss the remedies under consideration
(prior to selecting a final remedy). Once the owner or operator has
selected a remedy, he must place a description of the selected remedy
in the operating record, on the owner or operator's publicly accessible
internet site and notify the State Director.
7. Selection of Remedy
    This section of the final rule has been adopted with only minor
changes from the proposal. As in the prior section, EPA has revised
certain provision to reflect that this section will also apply to the
cleanup of contamination caused by a release from a CCR unit. EPA also
deleted a provision that had been adopted from the part 258
regulations, but that was determined to be inappropriate in a self-
implementing rule as it was too susceptible to potential abuse.
    Based on the results of the corrective measures assessment
conducted, the owner or operator must select a remedy. The selected
remedy must attain all of the performance standards listed in
subsection (b). Specifically, the remedy must protect human health and
the environment, attain the groundwater protection standards, control
the sources of releases so as to reduce or eliminate, to the maximum
extent practicable, further releases of appendix IV constituents into
the environment, and comply with any relevant standards for management
of wastes generated as a result of the remedial activities. EPA
included an additional criterion more directly related to remediation
of contamination associated with a release, such as from a collapse or
structural failure of a CCR unit, which requires the remedy to ``remove
from the environment as much of the contaminated material that was
released from the CCR unit as is feasible, taking into account factors
such as avoiding the inappropriate disturbance of sensitive
ecosystems.'' Together, these criteria reflect the major technical
components of any kind of clean up remedy.
    The rule also specifies decision criteria to be considered by the
owner or operator in selecting the most appropriate remedy. These
include: (1) Long and short term effectiveness, and degree of certainty
of success; (2) effectiveness of remedy in controlling the source to
reduce further releases; (3) ease or difficulty of implementation; and
(4) community concerns. Additionally, the rule requires the owner or
operator to specify a schedule for implementing and completing the
remedial activities. The rule requires the owner or operator to set the
schedule because it is impossible for EPA to establish a single
schedule appropriate for all possible situations; the schedule will
necessarily depend on the nature and size of the contamination, among
other factors. The rule outlines six factors to be considered in
establishing a schedule for completing remedies (Sec. Sec.
257.97(d)(1-6)). These factors are: (1) Extent and nature of
contamination; (2) reasonable probabilities of remedial technologies in
achieving compliance with the groundwater protection standards; (3)
availability of treatment or disposal capacity for CCR managed during
implementation of the remedy; (4) potential risks to human health and
the environment; (5) resource value of the aquifer; and (6) other
relevant factors. EPA had included one additional factor in the
proposal: ``The desirability of utilizing technologies that are not
currently available, but which may offer significant advantages over
already available technologies in terms of effectiveness, reliability,
safety, or ability to achieve remedial objectives.'' EPA considered
that this provision, which could be used to justify delaying
remediation measures, was potentially subject to abuse and thus,
inappropriate to be included in a self-implementing rule.
    For similar reasons, EPA deleted the provisions in the proposal,
subsections (e) and (f) that would authorize a facility to determine
that remediation of a release is not necessary. These sections which
came from the MSWLF rule in part 258 are appropriate where there is
state oversight. The preamble to the final MSWLF rule specifically
discusses situations in which an approved state may decide not to
require cleanup of hazardous constituents released to groundwater from
a MSWLF (see 56 FR 51090). However, there is no similar guarantee that
an individual facility will act in the public interest.
8. Implementation of the Corrective Action Program
    The proposed rule required the owner or operator to include a
schedule for initiating the remedial activities in the schedule for
implementing the remedy (Sec.  257.97(d)). The Agency understands that
selecting a remedy is closely related to the assessment process and
cannot be accomplished unless a sufficiently thorough evaluation of
alternatives has been completed. The process of documenting the
rationale for selecting a remedy requires that a report be placed in
the operating record that clearly defines the corrective action
objectives and demonstrates why the selected remedy is anticipated to
meet those objectives. The report must identify how the remedy will be
protective of human health and the environment, attain the groundwater
protection standards (either background or MCLs), attain source control
objectives, and comply with waste management standards.
    The selection of a remedy also involves a public meeting with
interested parties before finally selecting a remedy. For these
reasons, the Agency is not establishing a deadline for completing the
remedy selection process, but rather expects it to be completed as soon
as practicable. Once the assessment of corrective measures has been
completed within the timeframe specified in this rule, and the public
meeting has occurred, the facility owner or operator must select a
remedy and begin implementing that remedy as soon as is practicable. It
is vitally important that the facility selects a remedy as soon as
practicable and begins designing and implementing that remedy, so that
releases to groundwater are addressed without unnecessary delay. EPA
understands that there are a variety of activities that may be
necessary in order to select the appropriate remedy (e.g., discussions
with affected citizens, state and local governments; conducting on-site
studies or pilot projects); and, once selected, to implement the remedy
(e.g., securing on-site utilities if needed, obtaining any necessary
permits, etc.). That is why EPA does not find it appropriate to set
specific timeframes for selecting the remedy or to begin implementing
the selected remedy. However, in order to ensure that the community is
kept informed as to the progress of selecting and implementing the
remedy, EPA is requiring that the facility owner or operator, on a
semiannual basis, post status reports/updates on their progress

to their publicly accessible internet site and submit these to the
state.\118\
---------------------------------------------------------------------------

    \118\ As evidenced in 42 U.S.C. 6971(f), Congress intended that
the OSHA be able to enforce its regulations to protect workers
exposed to hazardous waste and that EPA and OSHA would work together
to ensure that. EPA is clarifying that it intends that the CCR
disposal rule not preempt applicable OSHA standards designed to
protect workers exposed to CCRs; thus EPA's final rule on CCR
disposal will apply in addition to any applicable OSHA standards.
The Agency has added specific regulatory language in this section to
address this intent.
---------------------------------------------------------------------------

    However, the Agency has concluded that it is reasonable to require
that once a remedy has been chosen, the owner or operator of the CCR
unit must begin to implement that remedy within a specified period of
time. Consistent with the timeframes throughout this section, the final
rule requires that within 90 days of selecting a remedy, the owner or
operator must have initiated corrective measures, including any interim
measures determined to be appropriate, and have established a
corrective action groundwater monitoring program (and begin following
it). (Sec.  257.98). This is a reasonable timeframe in which to begin
these activities based on EPA's long experience in conducting and
overseeing cleanup activities.
    The remedy would be considered complete when the owner or operator
demonstrates compliance with the groundwater protection standards for a
period of three consecutive years, and all other actions required to
meet the performance standards in Sec.  257.97(b) have been satisfied
(e.g., source control). The owner or operator must obtain certification
that the remedy is complete from a qualified professional engineer, and
must notify the State Director. The certification must also be placed
in the operating record and on the owner or operator's publicly
accessible Internet site.
    The Agency deleted the provision that allows an owner or operator
to determine that compliance cannot be reasonably achieved with any
currently available methods. The Agency determined that without state
oversight or a permitting program, that provision was potentially
subject to abuse and thus, inappropriate to be included in a self-
implementing rule.
9. Timing Overview
    The groundwater monitoring regulations require that the owner or
operator of existing CCR units must comply with Sec.  257.90-Sec.
257.94 within 30 months of the date of publication of the rule.
Essentially, that means that by the end of 30 months, the owner or
operator must (1) install the groundwater monitoring system; (2)
document the sampling and analysis procedures; (3) establish which
statistical tests will be used to determine exceedances; (4) sample all
wells to have a minimum of 8 samples for all appendix III and IV
parameters; and (5) determine if there is a statistically significant
exceedance of any appendix III parameter, which would trigger
assessment monitoring.
    New CCR units must comply with Sec. Sec.  257.90-257.93, including
the requirement under Sec.  257.94(b) to collect and analyze eight
independent samples from each well for the parameters listed in
appendix III and IV to this part to determine background levels for all
appendix III and IV constituents, before commencing operation.
Essentially, that means that before receiving CCR waste, the owner or
operator must (1) install the groundwater monitoring system; (2)
document the sampling and analysis procedures; (3) establish which
statistical tests will be used to determine exceedances; and (4) sample
all wells to have a minimum of eight samples for all appendix III and
IV parameters.
    If assessment monitoring is triggered, within three months the
owner or operator must sample all wells for all appendix IV
constituents (minimum of one sample) and resample (minimum of one
sample) all wells for all appendix III parameters and those appendix IV
constituents that were detected in the first round of sampling. The
owner or operator could also simultaneously use this three month
timeframe to demonstrate that the statistically significant increase
found in detection monitoring was due to another source or sampling and
analysis error. While conducting assessment monitoring, the owner or
operator must continue sampling for all appendix III constituents and
any appendix IV detected constituents semiannually. The owner or
operator must sample for all appendix IV constituents annually.
    The owner or operator must also establish groundwater protection
standards (MCL or background levels) for all appendix IV constituents
detected during sampling.
    If one or more appendix IV constituents are detected at
statistically significant levels above the groundwater protection
standards established, or a release from a CCR unit has been detected,
corrective action is triggered. The owner or operator must characterize
the nature and extent of the release by installing additional
monitoring wells, collecting data on the quantity and concentration
levels of regulated constituents in the released material, sampling and
notifying the State Director, local government officials, and any
persons who own land or reside on the land that overlies the plume if
the plume has migrated off site. The owner or operator must also place
the notification in their operating record and on their publicly
accessible Internet site.
    If corrective action is triggered, within three months the owner or
operator must initiate an assessment of corrective measures. If the CCR
unit is an unlined surface impoundment, the unit must stop receiving
CCR and non-CCR wastes and initiate closure of the unit or begin to
retrofit the unit within six months. The owner or operator could also
simultaneously use these three months to initiate an assessment of
corrective measures to demonstrate that the statistically significant
increase found during assessment monitoring was due to another source
or sampling and analysis error.
    The assessment of corrective measures must be completed in three
months, with the possibility of an additional two months if the owner
or operator demonstrates the need for additional time. The owner or
operator must continue assessment monitoring and provide notification
of the corrective measures assessment to the State Director and place
the assessment in the operating record and on the owner's or operator's
publicly accessible Internet site. The owner or operator also must
discuss the results of the corrective measures assessment at least one
month prior to selection of remedy in a public meeting.
    Within three months of selecting a remedy, the owner or operator
must initiate remedial activities. Corrective action is completed when
the owner or operator demonstrates compliance with the groundwater
protection standards for three consecutive years.

L. Closure of Inactive Units.

    As discussed in Unit VI.A of this document, EPA proposed that
inactive CCR surface impoundments that had not completed closure in
accordance with specified standards by the effective date would be
subject to all of the requirements applicable to existing CCR surface
impoundments. EPA adopted this approach to create an incentive to
expedite the closure of these units, with all of the significant risk
mitigation that such a measure would entail. EPA is retaining this
general approach in the final rule, but has revised the provision to
grant inactive CCR surface impoundments more time to complete closure,
consistent with the other closure provisions in the final rule. The

final rule extends the deadline to three years from publication of the
rule in the Federal Register.
    The proposal was based on EPA's belief that the timeframes between
publication of the final rule and the effective date would be
sufficient for facilities to close inactive CCR surface impoundments.
This was particularly true under the subtitle C option, where the
timeframe between publication and the effective date could be as long
as 18 months, due to the need for subsequent action by authorized
states. Under the proposed rule, the maximum amount of time a facility
would have to initiate and complete closure of a disposal unit was
seven months. However, as discussed elsewhere in this preamble, EPA
received numerous comments raising concern that these timeframes would
essentially be ``impossible to meet'' for surface impoundments located
in certain geographic and climatic conditions, as well as for all of
the larger units. These comments convinced EPA that it had not
adequately accounted for the complexities inherent in electric
generating facility operations, and the different characteristics of
CCR surface impoundments in designing the closure provisions in the
proposal. EPA has revised the timeframes applicable to closures in the
final rule accordingly in light of these issues. See Unit VI.M of this
document. These same considerations apply with respect to this
provision, and additional time is therefore necessary to make this
option truly viable.
    EPA selected three years based primarily on two factors. EPA
initially focused on the minimum amount of time necessary to close a
CCR surface impoundment. As discussed in more detail in Unit VI.M of
this document, there can be a substantial range in the amount of time
needed to close a surface impoundment, depending on, for example, the
size and location of the unit.
    However, a critical factor in EPA's decision is that under this
approach these units will not be subject to the rule's groundwater
monitoring or structural stability requirements (provided they complete
closure within three years). Moreover, based on the information in the
record, it appears highly unlikely that groundwater monitoring is
currently being conducted at these units (as discussed in Unit IV.A of
this document, the information on groundwater monitoring requirements
applicable to existing units was extremely sparse, but many older units
appear to lack effective groundwater monitoring systems). EPA
considered that allowing these inactive units to remain in place
without taking measures to address the continuing threat that these
units present for a substantial amount of time could not be justified.
EPA therefore focused on the amount of time authorized under the rule
for implementation of the groundwater monitoring requirements (i.e., 2
years from the effective date) and for key structural stability
requirements (i.e., 18 months to complete key analyses).
    As discussed in more detail in the next section, the information in
the record demonstrates that it is feasible to complete the closure of
CCR surface impoundments within three years. EPA recognizes that larger
CCR surface impoundments (i.e., above 40 acres) may not be able to
close within this timeframe. However, to be able to support this
provision, EPA must balance the risk mitigation achieved by closure of
CCR surface impoundments against the risks inherent in allowing
inactive CCR surface impoundments to remain in place for longer periods
of time. The longer inactive CCR impoundments remain without all of the
protections provided by the final rule, the greater the potential for
significant health and environment impacts. Larger units are also the
ones more likely to present the highest risks, and so warrant the
greater oversight provided by application of all of the technical
criteria to their operation (and closure). Consequently, EPA is unable
to justify expanding this option to include the longer timeframes
available under Sec. Sec.  257.102 or 257.103.
    The criteria for conducting the closure of inactive CCR surface
impoundments are essentially the same as those applicable to active CCR
units. Inactive units can either clean close units, or close with waste
in place, subject to same performance standards in Sec.  257.102 for
all other CCR units. If an inactive CCR surface impoundment is
completely closed within the three year timeframe, no other
requirements apply to that unit. This means that no groundwater
monitoring or other post-closure care requirements would apply to these
units. Once an inactive CCR surface impoundment has been breached and
dewatered, the risks are essentially the same as the risks associated
with an inactive CCR landfill, which are not subject to any
requirements under the final rule.
    However, owners or operators of inactive CCR surface impoundments
that have not completed closure within this timeframe must comply with
all of the requirements applicable to existing CCR impoundments. If the
facility intends to maintain the inactive unit indefinitely, whether to
provide potential future capacity, or to continue to dredge the unit to
provide material for beneficial use, or with the idea that it may be
repurposed for other facility operations (e.g., to manage stormwater),
there is no basis for distinguishing between these units and actively
managed units on the basis of the potential risks. Thus, such units
would need, for example, to meet all of the location and structural
stability criteria (which could independently compel closure of the
unit), install the groundwater monitoring system, and begin to monitor
within the timeframes established in the final rule. This also means
that any facility that initiates closure under this provision but fails
to complete it within this timeframe, must comply with all groundwater
monitoring requirements in Sec. Sec.  257.90-98 (e.g., install
groundwater monitoring wells) as well as all of the post-closure care
requirements.

M. Closure and Post-Closure Care

    Closure and post-closure care are an integral part of the design
and operation of CCR landfills and CCR surface impoundments.\119\ EPA
solicited public comment on closure and post-closure care requirements
under a subtitle D approach in the proposed rule and sought additional
comment on specific closure requirements in a subsequent notice of data
availability.
---------------------------------------------------------------------------

    \119\ As discussed in the proposed rule, EPA's ``Guide for
Industrial Waste Management'' documents the general consensus on the
need for effective closure and post-closure care requirements
(Chapter 11). This guide can be accessed at http://www.epa.gov/epawaste/nonhaz/industrial/guide/.
---------------------------------------------------------------------------

    For CCR landfills, the proposed closure and post-closure care
requirements were modeled on current regulations that apply to
municipal solid waste landfills, which are codified in part 258. In
some cases, the proposed requirements were modified to reflect the lack
of a mandatory permitting mechanism (see Unit V.A. of this preamble for
additional information), in addition to other changes EPA believed were
appropriate to ensure that there would be no reasonable probability of
adverse effects from the wastes that remain after a CCR unit had
closed. For CCR surface impoundments, the Agency modeled the proposed
requirements on current regulations that apply to interim status
hazardous waste surface impoundments, which are codified in part 265.
Some additional proposed provisions were based on requirements
currently applicable to water, sediment, or slurry impoundments and

impounding structures that are regulated by the MSHA. See 30 CFR part
77, subpart C.
    The proposed rule included a number of closure and post-closure
criteria, including: (1) Requirements to prepare closure and post-
closure plans; (2) requirements for conducting closure of a CCR unit
when the CCR is removed and when the CCR is left in place, including
design criteria for a final cover system; (3) timeframes to commence
and complete closure activities; (4) closure and post-closure care
certification requirements; and (5) requirements for conducting post-
closure care. The Agency received numerous comments on the proposed
closure and post-closure criteria, with the majority of comments
pertaining to the proposed timeframes for closure (i.e., timeframes for
commencing and completing closure) of a CCR surface impoundment. As a
result of these comments, EPA solicited additional comments on the
timeframes for closure in a NODA published on August 2, 2013 (NODA 3).
See 78 FR at 46944. The sections below explain the approach and
rationale for the final rule closure and post-closure care criteria
based on the comments received in response to the proposed rule and the
NODA.
1. Closure Plan
    The Agency proposed to require that the owners or operators of CCR
landfills and CCR surface impoundments prepare a written closure plan
describing the closure of the unit and providing a schedule for
implementation of the plan. 75 FR at 35207-08. The closure plan would
describe the steps necessary to close the CCR unit at any point during
the active life based on recognized and generally accepted good
engineering practices. The proposal also identified the minimum
information necessary to include in the closure plan. This information
included: (1) An estimate of the largest area of the CCR unit that
would ever require a final cover during the active life of the CCR
unit; (2) an estimate of the maximum inventory of CCR that would ever
be present on-site over the active life of the CCR unit; (3) a
description of the final cover and the procedures to be used to install
the final cover; (4) a description of how the facility will provide for
major slope stability following closure; (5) a description of the
measures the owner or operator will adopt to preclude the probability
of future impoundment of water, sediment, or slurry; and (6) a schedule
for the implementation of the closure plan. See proposed Sec.
257.100(a) and (g). The proposed rule would also have required each
owner or operator to develop the closure plan by the effective date of
the final rule. Finally, EPA proposed to require the owner or operator
to have the closure plan certified by an independent registered
professional engineer, in addition to complying with all of the
notification and posting requirements under the rule.
    EPA received few public comments on either the proposal to develop
a closure plan or the individual elements of the closure plan. Some
commenters generally supported the requirement for an owner or operator
to develop a closure plan for the CCR unit, and no commenters opposed
it. However, one commenter requested that EPA include more specific
requirements for slope stability in the regulatory language beyond the
general requirement to address major slope stability in the closure
plan for units that close with waste in place.
    The Agency agrees that the proposed regulatory language should
provide more specific criteria defining the expectations with regard to
major slope stability. The proposed regulation merely required the
owner or operator to ``provide for major slope stability'' in the
closure plan, or in other words, to include measures to ensure that
slope stability issues will be accounted for in designing the final
cover. See 75 FR 35252.
    EPA explained that unit closure must provide for major slope
stability to prevent the sloughing of the cover system over the wastes
that will remain in the CCR unit over the long term. Sloughing of a
land slope can occur when the earth material becomes saturated with
water and incapable of maintaining the slope resulting in the movement
or sliding of the earth material. 75 FR at 35209. Slope stability is a
critical issue in the design of final cover systems for both surface
impoundments and landfills because cover system slope instability has
been attributed to a number of final cover system failures.\120\ More
specifically, the primary causes of final cover system slope failure
during construction have been identified as: (1) Placing soil over the
sideslope geosynthetics from the top of the slope downward, rather than
the toe of the slope upward; (2) using presumed values for critical
interface shear strengths that were not conservative; and (3) using
interface shear strength values from laboratory tests performed under
conditions not representative of the actual field conditions. For final
cover system slope failures after rainfall or thaw, the primary causes
of failure have been identified as: (1) Not accounting for seepage
forces; (2) clogging of the internal drainage layer, which leads to
increased seepage forces; and (3) not accounting for moisture at the
geomembrane and compacted clay liner interface (which weakened the
interface) due to both rain falling on the compacted clay liner surface
during construction and freeze-thaw effects.
---------------------------------------------------------------------------

    \120\ USEPA, ``Assessment and Recommendations for Improving the
Performance of Waste Containment Systems,'' EPA/600/R-02/099,
December 2002.
---------------------------------------------------------------------------

    Given that slope stability is a critical issue in the design and
eventual performance of a final cover system, EPA has adopted a new
criterion in the performance standard that all closures must meet: The
owner or operator must ensure that the CCR unit is closed in a manner
that will ``provide for major slope stability to prevent the sloughing
or movement of the final cover system during closure and throughout the
post-closure care period.'' See Sec.  257.102(d)(1)(iii). Or in other
words, the owner or operator must design a final cover system with any
measures necessary to ensure that the major slopes of the closed CCR
unit remain stable. Consistent with the proposal, the closure plan must
discuss how the final cover system will achieve the performance
standards specified in the regulation, which will necessarily include
how the measures taken to address major slope stability. As explained
in the proposed rule, the original provision was based on existing MSHA
standards, specifically the requirements under 30 CFR 77.216-5 which
apply to abandoned water, sediment or slurry impoundments and
impounding structures.\121\ 75 FR 35208-09. Under these requirements
major slope stability includes long term stability considerations, such
as ``erosion control, drainage, etc.'' These issues are equally
relevant to the closure of CCR units, and EPA expects facilities to
account for these factors in their final closure plans.
---------------------------------------------------------------------------

    \121\ The term ``abandoned'' is defined in the MSHA regulations
under 30 CFR 77.217, and as applied to an impoundment or impounding
structure such term means that work on the structure has been
completed in accordance with a plan for abandonment approved by the
District Manager.
---------------------------------------------------------------------------

    The remaining information elements of the closure plan have been
adopted without revision (although EPA has reorganized the final
regulatory text for greater clarity). These are briefly summarized
below:
    a. An estimate of the largest area of the CCR unit ever requiring a
final cover during the active life of the CCR unit. If

the owner or operator routinely closes portions of a CCR unit as the
design capacity is reached, the closure plan should indicate the
largest area of the CCR unit that will be open (and requiring a final
cover) at one time.
    b. An estimate of the maximum inventory of CCR ever on-site over
the active life of the CCR unit. If the owner or operator routinely
closes portions of a CCR unit as the design capacity is reached, the
closure plan should indicate the maximum inventory of CCR that will be
open (and requiring a final cover) at one time.
    c. A description of the final cover and the procedures to be used
to install the final cover. The closure plan should also discuss how
the closure performance standard will be achieved.
    d. A description of the provisions to preclude the probability of
future impoundment of water, sediment, or slurry. The final grades of
the final cover system should promote surface water run-off and
minimize erosion. The closure plan should also discuss the steepness of
the slopes of the final cover system, in addition to the vertical
spacing and width of benches.
    e. A schedule for the implementation of the closure plan.
    This rule also provides new procedures for amending an existing
written closure plan. While the proposed rule did not specifically
allow or require the owner or operator to revise an existing closure
plan, EPA recognizes that available information and conditions known at
the time the closure plan is prepared may very well change during the
active life of the CCR unit, which could be decades in some cases. In
order to eliminate any potential confusion over whether an owner or
operator is allowed under this rule to revise the closure plan to
reflect a change in conditions or circumstances, the final rule adopts
new procedures for amending a written closure plan. These new
procedures allow the owner or operator to revise the closure plan at
any time provided the revised plan is placed in the facility's
operating record, in addition to complying with all of the notification
and posting requirements under the rule. Furthermore, the final rule
requires the closure plan be amended any time there is a change in
conditions that would substantially affect the written closure plan in
effect.
    Finally, in a departure from the proposed rule, the final rule
provides owners and operators one year from the rule's effective date
to prepare the initial written closure plan, which is one year longer
than proposed. EPA made this change as part of its effort to coordinate
the compliance and implementation timeframes in the CCR rule with
another Agency rulemaking--the Effluent Limitations Guidelines and
Standards for the Steam Electric Power Generating Point Source Category
(ELG) rulemaking--that may affect owners and operators of CCR units.
See 78 FR 34442. As explained in that proposal, consistent with RCRA
section 1006(b), EPA has sought to effectively coordinate any final
RCRA requirements with the ELG requirements, to minimize the overall
complexity of these two regulatory structures, and to facilitate the
implementation of engineering, financial and permitting activities.
EPA's goal is to ensure that the two rules work together to effectively
address the discharge of pollutants from steam electric generating
facilities and the human health and environmental risks associated with
the disposal of CCRs, without creating avoidable or unnecessary
burdens.
    EPA proposed to require facilities to complete a closure plan by
the rule's effective date, or six months following the rule's
publication. However, this would have required owners or operators to
prepare closure plans approximately three months prior to publication
of the ELG final rule. Given that an understanding of the ELG rule
would likely affect the details and content of a closure plan, the
Agency concluded that it would make no sense to require an owner or
operator to prepare a closure plan within six months, only to have them
update it months later, after the owner or operator understands the
requirements of both the CCR and ELG final rules. No measureable
environmental or health benefit would be gained by having a closure
plan in place for those three months. Moreover, EPA wants to ensure
that closure plans are well considered, and the knowledge that a plan
may need to be substantially revised in the near future could create a
contrary incentive.
    By extending the deadline for preparation of the closure plan by
one year, owner or operators will have slightly more than six months
after the ELG rule is published to complete a closure plan. This is
consistent with the six month timeframe EPA originally proposed, which
as noted, would have required completion of the closure plan within six
months of publication of the final CCR rule.
2. Closure of a CCR Unit Through Removal and Decontamination
    The proposed rule would have allowed facilities to close a CCR unit
either through CCR removal and decontamination of all areas affected by
releases from the CCR unit (``clean closure'') or with CCR in place
with a final cover system. The Agency proposed that if the owner or
operator elects to clean close a CCR unit, CCR removal and
decontamination are complete when constituent concentrations throughout
the CCR unit and any areas affected by releases from the CCR unit do
not exceed the numeric cleanup levels for those constituents found in
CCR established by the state in which the CCR unit is located, to the
extent that the state has established cleanup levels. 75 FR 35208. In
the absence of state cleanup levels, the proposal stated that metals
should be removed to either statistically equivalent background levels,
or to maximum contaminant levels or health-based numbers. Once a
facility had completed clean closure of a CCR unit, EPA proposed that
post-closure care would not be required for that unit. EPA also noted
that it was considering whether to adopt a further incentive for clean
closure, under which the owner or operator could remove the deed
notation required under the proposed rule, once all CCR has been
removed from the facility and notification provided to the state.
    Several commenters urged EPA to not require clean closure as the
only method of closing a CCR unit, arguing that clean closure is not
feasible or not necessary. Others acknowledged that clean closure is
not only a viable option for their CCR units, but in some cases it
would be ``the only prudent closure option.'' A few commenters
suggested criteria to determine the conditions under which clean
closure would be appropriate. For example, one commenter agreed with
EPA that the risk-based corrective action process (RBCA) would be
useful in determining whether waste removal is appropriate at the site.
    EPA received relatively few comments on the specific standards for
conducting clean closure. One commenter identified six criteria that
should be included in any final regulation in order to allow a facility
to have been deemed to have completed clean closure of a CCR surface
impoundment and thereby avoid post-closure care. Some of the
commenter's suggestions were comparable to requirements in the
proposal. However the commenter also included requirements to ensure
that adequate engineering controls were used to prevent contamination
of soil and groundwater during excavation, and requirements for
quarterly monitoring of shallow groundwater beneath the surface
impoundment for a period of five years to demonstrate that no

residual CCR was left in place. Finally, a number of commenters
supported a provision that would allow the owner or operator to remove
the deed notation required provided all CCR is removed from the site.
    EPA did not propose to require clean closure nor to establish
restrictions on the situations in which clean closure would be
appropriate. As EPA acknowledged in the proposal, most facilities will
likely not clean close their CCR units given the expense and difficulty
of such an operation. Because clean closure is generally preferable
from the standpoint of land re-use and redevelopment, EPA has
explicitly identified this as an acceptable means of closing a CCR
unit. However, both methods of closure (i.e., clean closure and closure
with waste in place) can be equally protective, provided they are
conducted properly. Thus, consistent with the proposal, the final rule
allows the owner or operator to determine whether clean closure or
closure with the waste in place is appropriate for their particular
unit. EPA agrees that the RBCA process, using recognized and generally
accepted good engineering practices such as the ASTM Eco-RBCA process,
can be a useful tool to evaluate whether waste removal is appropriate
at the site. It is, however, not a necessary prerequisite.
    EPA has adopted the provisions governing clean closure from the
proposed rule with only one revision. The final provisions consist of
two performance standards: First, the owner or operator must remove all
CCR from the unit and decontaminate all areas affected by releases from
the CCR landfill or surface impoundment. As part of meeting this
performance standard, the final rule requires facility owners or
operators to remove all wastes from the closing unit, and remove all
liners contaminated with CCR waste and CCR waste leachate. The final
rule also requires the owner or operator to remove and decontaminate
all areas affected by releases from the CCR unit. This would require
removal or decontamination of the underlying and surrounding soils and
flushing, pumping, and/or treating the aquifer. The Agency interprets
the term ``soil'' broadly to include both unsaturated soils and soils
containing groundwater.
    Second, the final rule specifies that closure has been completed
when all CCR in the unit and any areas affected by releases from the
CCR unit have been removed and groundwater monitoring demonstrates that
all concentrations of the assessment monitoring constituents listed in
appendix IV to part 257 do not exceed either statistically equivalent
background levels or MCLs. This standard encompasses both saturated and
unsaturated soils, as well as the groundwater. As part of attaining
this standard, facility owners and operators will need to document that
any contaminants left in the subsoils (i.e., contaminated groundwater
left in soils below the former landfill or impoundment) will not impact
any environmental media including groundwater, surface water, or the
atmosphere in excess of Agency-recommended limits or factors.
Typically, any metals in these ``subsoils'' in excess of background
levels are allowed to either naturally attenuate, or are removed by
flushing. Once the facility has removed all of the assessment
monitoring constituents listed in appendix IV down to background levels
or MCLs the groundwater is considered to be ``clean'' and closure is
complete.
    EPA disagrees that specific provisions requiring the use of
adequate engineering controls to prevent contamination of soil and
groundwater during excavation are necessary to ensure that closure will
be protective. To the extent that any contamination of soil or
groundwater has occurred during CCR removal, this would constitute a
release (or an ``area affected by a release'') from the CCR unit, and
the final performance standard requires the facility to ensure that
this has been removed before closure is deemed to be complete.
    Contrary to the commenter's suggestion that quarterly monitoring
for five years is necessary to demonstrate that no residual CCR was
left in place, the rule requires a facility to document that all
appendix IV concentrations are below MCL or background levels for two
consecutive sampling events, using the statistical procedures in Sec.
257.93(g). This is the same sampling required to demonstrate under the
groundwater monitoring program that there is no longer a reason to
suspect a source of contamination, and that consequently assessment
monitoring can cease. EPA selected these provisions as the most
factually analogous to the circumstances surrounding the clean closure
of a CCR unit. Once a facility has removed the waste and any liner, the
presumption is that the source of contamination has been removed as
well. Although there may be site-specific factors that could support
the need for a longer monitoring period, there is no factual basis to
require a longer minimum period of sampling on a national basis.
    This represents a change from the proposal. EPA proposed a
performance standard that required decontamination to either any state
established numeric cleanup levels for CCR constituents, or in the
absence of state cleanup levels, the removal of metals to either
statistically equivalent background levels, or to MCLs, or health-based
numbers. This was taken directly from the current part 258 standards
for MSWLFs. EPA has deleted both of these standards as inappropriate
for these units.
    The reference to state established clean up levels was
inadvertently carried over from the existing part 258 regulations. As
explained throughout this preamble, EPA is unable to rely on state
programs to establish the specific standards under this rule; the
record does not contain information on all state cleanup standards, and
there is no mechanism for states to operate approved programs in lieu
of federal programs.
    EPA determined that the requirement to clean all soils to
background levels was equally inappropriate. In practice, EPA does not
routinely require complete removal of all contamination (that is,
cleanup to `background') from a closing unit even for hazardous waste
units. Requiring CCR units to clean up soils to levels before the site
was contaminated, would be more stringent than current hazardous waste
policies. There is no basis in the current record to impose provisions
for the remediation of CCR units that are more stringent than those
imposed on hazardous wastes.
    Upon completion, the unit is exempt from the groundwater monitoring
and any other post-closure care requirements. In addition, the final
rule adopts the proposal to allow the owner or operator to remove the
deed notation required under Sec.  257.102(i)(4), upon certification
that clean closure has been completed. EPA proposed this option to
create a further incentive for clean closure, and it is clear from the
commenters, who uniformly supported this option, that it does so. Some
commenters raised concern about the effect this option will have on
state laws, which may not allow the deed notation to be removed. EPA
notes that these criteria do not preempt state laws; to the extent
state law requires the facility to retain a deed notation despite the
completion of clean closure, those requirements will remain in place,
notwithstanding this final rule.
3. Closure of a CCR Unit With CCR in Place
    The proposed rule would have also allowed facilities to close a CCR
unit by leaving the CCR in place and installing a final cover system.
The final cover

system would have been required to be designed and constructed to a
have a permeability less than or equal to the permeability of any
bottom liner system or the natural subsoils present, or a permeability
no greater than 1 x 10-5 centimeters per second (cm/sec),
whichever is less. The proposal would have also required an
infiltration layer that contains a minimum of 18 inches of earthen
material and an erosion layer containing a minimum of six inches of
earthen material that is capable of sustaining native plant growth to
help minimize erosion of the final cover. These proposed requirements
were generally modeled after the performance standard and technical
requirements contained in Sec.  258.60 for MSWLFs. 75 FR 35208. EPA
also proposed that the final cover system would have to be designed to
minimize the disruption of the final cover through a design that
accommodates settling and subsidence and provides for major slope
stability to prevent the sloughing of the closed CCR unit over the long
term. These last two criteria are based on existing requirements for
interim status units under RCRA part 265 and MSHA requirements under 30
CFR part 77, subpart C, respectively.
    As proposed, CCR surface impoundments would have been subject to an
additional set of performance standards. The owner or operator of a CCR
surface impoundment would have been required to either drain the CCR
unit or solidify the remaining wastes. In addition, the owner or
operator would have been required to stabilize the wastes to a bearing
capacity to support the final cover. The proposed criteria would also
have required that the final cover for all CCR units be designed to
minimize the migration of liquids through the closed CCR surface
impoundment over the long term; promote drainage, and accommodate
settling and subsidence so that the final cover's integrity is
maintained. Finally, closure of the CCR unit would also have been
subject to the general performance standard that the probability of
future impoundment of water, sediment, or slurry be precluded.
    The Agency also proposed to allow owners or operators of CCR units
to select an alternative final cover design. As proposed, the
alternative final cover design would have required an infiltration
layer that achieves an equivalent reduction in infiltration, and an
erosion layer that would provide equivalent protection from wind and
water erosion, as the infiltration and erosion layers specified for
final covers described above. In addition, the proposed approach for
alternative final cover designs would have also required certification
by an independent registered engineer, notification being provided to
the state that the alternative final cover design has been placed in
the facility's operating record, and placement of the alternative final
cover design on the owner or operator's publicly accessible Internet
site.
a. Final Cover System Design
    EPA received comments supporting the proposed approach, while other
commenters opposed the proposed final cover system design requirements.
One state commenter generally supported using the part 258 final cover
design requirements as a general model for CCR units. This commenter
also requested that the Agency clarify whether new CCR units would be
required to install a composite final cover system given that it was
proposed that new CCR units would be required to designed and
constructed with a composite bottom liner. Another state indicated that
its state regulations allow final cover designs similar to that
proposed by EPA, although the state requires a 24 inch infiltration
layer and a 12 inch erosion layer. Another commenter referenced current
research showing that soil-only covers may not be effective in
minimizing infiltration over the long term under certain climates. This
commenter recommended that a geomembrane should be made a standard
component of the cover system. Other commenters stated that the final
cover system should be a composite system consisting of a synthetic
component and a low permeability clay component. A state commenter
offered that post-closure maintenance of composite cap system
incorporating a geomembrane has been challenging in that state. Another
commenter stated that a compacted clay liner should not be used as a
final cover for landfills due to the potential for settlement cracking,
desiccation cracking, and root and animal penetration. Instead, it was
suggested that if a single barrier system is used, then a benefit-cost
analysis favors a geomembrane, and if a composite barrier is to be
used, a benefit-cost analysis favors a composite system of a
geomembrane and geosynthetic clay liner.
    The Agency also received many comments on the proposed approach to
allow the use of alternative final cover systems. Most commenters
supported allowing the use of alternative covers. One commenter stated
that the use of geosynthetic clay liners in lieu of 18 inches of
earthen material for the infiltration layer is a commonly accepted for
cover systems for MSWLFs. This commenter also noted that that
geosynthetic clay liners have documented permeability characteristics
on the order of 1 x 10-9 cm/sec. Another commenter supported
allowing the use of alternative cover systems because a one-size-fits-
all approach is not appropriate for final cover system designs. A state
also offered that appropriately designed alternative final covers such
as capillary barrier covers and evapotranspiration covers are being
successfully used at facilities in the state.
    After considering comments received regarding final covers, the
Agency is essentially finalizing the approach in the proposed rule with
minor revisions. The final rule allows owners or operators to use a
final cover system consisting of an infiltration layer and an erosion
layer, provided the infiltration layer has a permeability less than or
equal to the bottom liner or natural subsoils. However, regardless of
the bottom liner or natural subsoils present, the final cover must have
a permeability no greater than 1 x 10-5 cm/sec.
    To address the commenters' concerns that the final cover system may
not function effectively as designed over the long term under certain
circumstances, the rule also includes a performance standard that any
final cover system must meet. This standard is modeled after the
closure performance standard applicable to interim status hazardous
waste units under Sec.  265.111. The final rule requires that any final
cover system control, minimize or eliminate, to the maximum extent
practicable, post-closure infiltration of liquids into the waste and
releases of leachate (in addition to CCR or contaminated run-off) to
the ground or surface waters. Thus, a facility must ensure that in
designing a final cover for a CCR unit they account for any condition
that may cause the final cover system not to perform as designed. This
could include accounting for site conditions that may increase the
likelihood that a cover would be susceptible to desiccation cracking or
settlement cracking. Under this performance standard, if the cover
system results in liquids infiltration or releases of leachate from the
CCR unit, the final cover would not be an appropriate cover. The final
rule requires the final cover system design to be certified by a
qualified professional engineer that the design meets both the
performance standard and cover system criteria.
    The final rule does not require the use of composite final covers,
such as a geomembrane underlain by a compacted soil infiltration layer.
This is also the

case in situations for a CCR unit that is designed with a composite
bottom liner or if the permeability of the soil underlying the unit is
comparable to the permeability of a geomembrane. As EPA has concluded
for municipal solid waste landfills, in certain site-specific
situations it may be possible to construct an infiltration layer that
achieves an equivalent reduction in infiltration without matching the
permeability in the bottom liner material. 62 FR 40710.
    Nonetheless, in certain locations, composite cover systems may be
necessary to achieve the rule's performance standards. EPA acknowledges
that under certain circumstances issues can arise with compacted clay
barriers, particularly when used alone. These can include desiccation,
freeze-thaw sensitivity, and distortion due to total and differential
settlement of the underlying wastes. These issues can generally be
addressed through proper maintenance of the cover system; and in fact
the final rule requires as part of post-closure care that the owner or
operator maintain the integrity and effectiveness of any final cover,
including making repairs to the final cover to correct the effects of
settlement, subsidence, erosion, or other events, and preventing run-on
and run-off from eroding or otherwise damaging the final cover.
Consequently, EPA is not mandating the installation of a composite
liner system.
    However, fewer problems are typically seen with the use of
composite cover systems. And while ongoing oversight and proper
maintenance is necessary to ensure the efficacy of any cover system,
less effort is generally involved to ensure the continued performance
of a composite cover system. EPA therefore generally recommends that
facilities install a composite cover system, rather than a compacted
clay barrier, as the composite system has often proven to be more
effective (and cost effective) over the long term. For these reasons,
EPA also anticipates that composite cover systems will be recommended
in many circumstances by qualified professional engineers.
    The final rule also allows the use of an alternative final cover.
The rule requires that the alternative final cover must include
infiltration and erosion layer that achieve equivalent performance as
the minimum designs specified for final cover systems as discussed
above. As discussed in the proposed rule, EPA included this provision
to increase the flexibility for an owner or operator of a CCR unit to
account for site-specific conditions. Moreover, these provisions will
provide an opportunity to incorporate future technology improvements
that would be missed if the rule required prescriptive design measures.
In addition, these requirements would not supersede more stringent
state requirements. Thus, if a state either has more prescriptive or
more stringent standards in its state regulations applicable to CCR
units, those state requirements would control any final cover system or
alternative final cover system design.
    While the rule provides the owner or operator flexibility in
selecting the final cover for the unit, EPA remains concerned about the
lack of guaranteed state oversight on final cover selection. A final
cover system that does not perform as designed may result in
unacceptable infiltration of water into the closed CCR unit that may
lead to leachate and releases from the unit. To address this concern,
as well as the concerns raised by commenters regarding the long-term
performance of certain cover systems by providing further assurance
that the final cover system will perform over the long term, EPA has
deleted the proposed provision that would have allowed owners or
operators to shorten the length of the post-closure care period. As
discussed in Unit M.9 below, the final rule requires facilities to
conduct post-closure care for all CCR units for 30 years.
b. Performance Standards When Leaving CCR in Place
    EPA received no significant comments on the proposed performance
standards. The Agency is therefore finalizing these requirements
without revision from the proposal (although EPA has reorganized the
final regulatory text for greater clarity). The performance standards
are summarized below:
    i. As discussed in the previous section, the CCR unit must be
closed in a manner that will control, minimize or eliminate, to the
maximum extent practicable, post-closure infiltration of liquids into
the waste and releases of CCR, leachate, or contaminated run-off to the
ground or surface waters.
    ii. The CCR unit must be closed in a manner that will preclude the
probability of future impoundment of water, sediment, or slurry.
    iii. The CCR unit must be closed in a manner that will provide for
major slope stability, which is discussed is Unit M.1 of this document
for closure plans above.
    iv. The CCR unit must be closed in a manner that will minimize the
need for further maintenance of the unit.
    v. The CCR unit must be closed in the shortest amount of time
consistent with recognized and generally accepted good engineering
practices. The Agency added this performance standard to be consistent
with the final provisions applicable for the timeframes for initiating
and completing the closure of CCR units.
4. Timeframes for Closure
    The Agency proposed that closure of a CCR landfill or CCR surface
impoundment must be initiated by the owner or operator no later than 30
days following the known final receipt of CCR. To address concerns
about ``inactive'' or abandoned units, the proposed rule also provided
that a CCR unit must initiate closure no later than one year after the
most recent receipt of CCR if the CCR unit had remaining capacity and
there was a reasonable likelihood that the CCR unit would receive
additional CCR (i.e., the rule would have forced the facility to close
the CCR unit). See 77 FR at 35209 and proposed Sec.  257.100(j). In
addition, the proposed rule would have required an owner or operator to
complete closure activities within 180 days of initiating closure. See
proposed Sec.  257.100(k). Thus, the maximum amount of time a facility
would have had to initiate and complete closure of a CCR unit was seven
months.
    While the existing closure criteria for MSWLFs allow the Director
of an approved State to grant time extensions for closure (both to
initiate and to complete closure) if steps are taken to prevent threats
to human health and the environment from the unclosed unit, EPA
proposed not to include similar provisions for owners or operators of
CCR units. At proposal, the Agency believed that extending the closure
deadlines was inappropriate because, in the absence of an approved
state program, the owner or operator could unilaterally decide to
extend the time for closure of a CCR unit, without any basis, or
oversight by a regulatory authority. 75 FR 35209.
    EPA received numerous comments in response to the proposed
deadlines under the subtitle D proposed approach. Industry and state
commenters stated that the proposed deadlines to begin and complete
closure activities (30 and 180 days, respectively) are technically
impracticable and simply too short for the vast majority of CCR units,
especially for CCR surface impoundments to complete closure. Commenters
stated that a 30-day deadline to initiate closure activities may not be
workable in situations such as when there are construction

limitations due to seasonal or climatic conditions, and should not be
required in circumstances when a coal-fired generating unit is
temporarily idled (e.g., maintenance related outages or an outage
corresponding with a CCR handling system conversion). Regarding the
amount of time needed to close a unit, numerous commenters noted that
it would be impossible to properly complete closure activities within
the proposed 180 days at most CCR surface impoundments due to the
length of time needed to dewater an impoundment and stabilize the
wastes prior to constructing the final cover system. For example,
commenters pointed out that dewatering of a surface impoundment alone
can take several years to complete because impoundments can be hundreds
of acres in size. One commenter provided information related to an
ongoing CCR surface impoundment closure where the dewatering and ash
stabilizing phases of closure took two years to complete. Commenters
also stated that because a large number of CCR units will have to be
closed during roughly the same timeframe, facilities may not be able to
obtain the necessary specialized personnel, equipment, and materials
(e.g., clay or fill material, liner materials) to close multiple units
simultaneously. This issue may be further complicated in locations
where multiple facilities are competing for the same limited resources.
Commenters further argued that adopting the same closure deadlines
applicable to MSWLFs is not appropriate given differences in size,
design, and operation (e.g., CCR surface impoundments contain large
volumes of water, MSWLFs typically close each component cell when it
reaches its disposal capacity). As a result of these concerns,
commenters recommended that EPA extend the deadlines both to commence
and complete closure activities. The majority of the these commenters,
however, urged EPA not to establish specific deadlines for closure and
instead require facilities to close a CCR unit consistent with a
closure plan approved by a state, or developed and certified by a
qualified professional, such as a professional engineer.
    In a subsequent NODA, the Agency solicited additional public
comment on several different options to address these concerns. 78 FR
at 46944-46. With respect to the deadline to initiate closure, EPA
presented several examples of routine and legitimate circumstances in
which CCR units would not receive CCR for periods longer than one year,
even though the facility intended to continue to use the unit. For
example, EPA discussed circumstances in which the facility alternates
between two surface impoundments, only one of which is operational at a
time. Once the impoundment has reached capacity, the facility dewaters
the unit, and begins to send CCR to the second impoundment. Once the
unit is dewatered, the CCR is excavated and disposed in an adjacent
landfill. The time to fill these units has varied over the years as
demand has fluctuated, but a typical time to fill a unit with CCR is
two years, perhaps longer, during which the other unit is ``idle,'' in
that it does not ``receive CCR,'' but it remains operational.
    The Agency also solicited comment on a revised approach to the
deadline to initiate closure. The approach entailed establishing a
rebuttable presumption that if the CCR unit has not received waste
within a particular period of time (e.g., 18-24 months), the CCR unit
would be considered inactive and unit closure would be required to
begin within a specified time. However, if the facility could
substantiate that there was a reasonable likelihood that the CCR unit
would again receive CCR in the future and also was able to document
certain findings, the owner or operator would not need to immediately
commence closure of the CCR unit. In the NODA, EPA discussed several
examples of situations that could support a demonstration that
immediate closure of the CCR unit was not necessary. One example was if
an owner or operator could document that a CCR unit had been dedicated
to a temporarily idled coal-fired generating unit and there was a
reasonable likelihood that CCRs would be disposed in the CCR unit once
the coal-fired generating unit resumed operation. Another situation
presented was a CCR unit dedicated to a coal-fired generating unit that
was not burning coal at the time (e.g., electricity was being generated
with other fuels such as natural gas), but the facility needed the CCR
unit following resumption of coal burning. A final example involved
normal facility operations that include periods during which the CCR
unit does not receive CCR for extended periods (e.g., the alternating
use of two CCR surface impoundments discussed above). As part of this
approach, the Agency solicited comment on whether to limit the length
of time an owner or operator can maintain an idle CCR unit.
    With respect to the deadline for completing closure, EPA
acknowledged in the NODA that different deadlines, at least for the
larger CCR units, were warranted. Information that the Agency has
obtained throughout the rulemaking confirmed commenters' claims that
the timeframes originally proposed to complete closure of CCR surface
impoundments will be practicably infeasible for the larger
impoundments. However, the Agency cautioned that any ultimate timeframe
provided in the rule that would be practicable for the largest CCR
units would be far too long to justify as timeframes for closure of the
smaller impoundments. EPA explained that it intended to examine
available closure plans for CCR surface impoundments to determine
whether there are consistent timeframes or other factors that EPA could
adopt as part of the regulations. EPA specifically identified two
closure plans of CCR units that were scheduled to close as a possible
source of useful information. These plans projected that closure would
take multiple years to complete for modestly-sized CCR surface
impoundments (i.e., less than 50 acres).
a. Deadlines To Initiate Closure
    In response to the NODA, most utility commenters stated that the
time to initiate closure should be tied to reasonable triggers that
account for the diverse uses of CCR surface impoundments and CCR
landfills. In particular, these commenters recommended that closure not
be initiated for an idled CCR unit if the CCR unit was expected to
receive additional waste in the future, whether CCR or any other waste
the unit may be authorized to manage. These commenters also supported
the scenarios EPA described in the NODA as examples of legitimate
situations that could warrant delaying the immediate closure of a CCR
unit. Many of these commenters generally agreed that the rebuttable
presumption alternative discussed in the NODA could be an appropriate
approach for closure, in particular for CCR units not covered by a
state-approved operating plan, provided the regulatory approach would
be implemented in a manner that did not restrict other legitimate uses
of the CCR unit. Many of these commenters also asserted that a limit on
the length of time a CCR unit can remain idle is not practical because
the owner or operator will not be able to predict with any degree of
certainty how long a CCR unit will be idled. Several of these
commenters also urged EPA to specify in the final rule what EPA
intended by the phrase ``initiation of closure;'' that is, that EPA
define the activities or actions the owner or operator must take by the
deadlines specified in the rule.
    A trade organization and other commenters warned that strict
restraints on the initiation (and completion) of

closure of CCR units would pre-empt opportunities for reclaiming CCR
from these CCR units for beneficial use of CCR. These commenters
recommended that the final rule create meaningful incentives for the
beneficial use of CCR already in CCR units which will become
unavailable to reclamation once a final cover system is put in place.
For example, one commenter suggested that an incentive could be
deferring deadlines for closure of a CCR unit if an owner or operator
reduces its net tonnage by a set amount, such as 10,000 tons per year,
if the CCR is beneficially used. EPA also received comments from
several states that generally supported the rebuttable presumption
concept. One state supported a longer rebuttable presumption time
period of three years that could be extended if approved by the state
on a case-by-case basis.
    After consideration of all of the public comments, the Agency is
adopting an approach that largely mirrors the approach outlined in the
NODA. Closure of a CCR unit is triggered in one of three ways. The
first is upon the known final receipt of waste (CCR or otherwise), or
when an owner or operator removes the known final volume of CCR from
the CCR unit for the purpose of beneficial use of CCR. Under these
scenarios, the final rule requires an owner or operator to commence
closure of the CCR unit within 30 days of such known final receipt or
known final volume removal, whichever date is later.
    The second way closure can be triggered relates to ``idled'' CCR
units. This applies to situations in which the CCR unit has remaining
disposal, treatment, or storage capacity, or there has been a temporary
pause in the removal activities of CCR from the CCR unit. In these
situations, the rule establishes a presumption that the owner or
operator must initiate closure of the CCR unit no later than two years
after the most recent receipt of CCR or any non-CCR waste stream, or no
later than two years after the most recent date that CCR was removed
from the CCR unit for the purpose of beneficial use, whichever date is
later. The rule, however, provides procedures for an owner or operator
of the CCR unit to rebut this presumption and obtain additional time,
provided the owner or operator can make the prescribed demonstrations.
    The final way closure is triggered is when a CCR unit fails to meet
certain of the technical criteria. Specifically, an owner or operator
may be compelled to close a CCR unit in the following circumstances:
(1) If the CCR unit has been sited inappropriately; i.e., cannot meet
the applicable location criteria; (2) if an unlined CCR surface
impoundment is found to contaminate groundwater in excess of a
groundwater protection standard; or (3) if a CCR surface impoundment
cannot demonstrate the minimum factors of safety regarding structural
integrity of the CCR unit. When closure is triggered under these
circumstances, the owner or operator must initiate closure of the CCR
unit within six months. Each of these is discussed in more detail
below.
i. ``Known Final Receipt'' of CCR
    Several commenters suggested that the rule not link the deadlines
to initiate closure solely to when a CCR unit ceases to receive CCR.
Many of these commenters provided information that CCR units also serve
functions other than managing CCR, including the management of other
wastes or water treatment. Thus, while there are periods of time that
certain CCR units will receive both CCR and non-CCR wastes, there are
also other times when the same CCR unit will only receive non-CCR
wastes or perform other forms of active waste management in the unit,
e.g., specific water treatment functions. EPA agrees that these are
legitimate waste management activities, and EPA is aware of no risks
that would warrant cessation of such activities simply because the unit
is no longer receiving CCR. Therefore, in response to these comments,
the final rule no longer requires closure based solely upon the receipt
of CCR. Instead, the final rule requires closure to be initiated after
the CCR unit ceases to receive any waste or waste stream into the CCR
unit. See Sec.  257.102(e)(1) and (e)(2) in the rule.
    The Agency also agrees with those commenters that supported
delaying the commencement of closure of a CCR unit if substantial
quantities of CCR are removed from the CCR unit for the beneficial use
of the waste. This could include, for example, removal of CCR from a
CCR unit followed by its use as a partial replacement for Portland
cement. As discussed in Unit IV.B of this preamble, EPA has identified
significant benefits from reducing the disposal volumes of CCR in CCR
landfills and CCR surface impoundments, including reduced risks
associated with the practice of CCR disposal, benefits from reducing
the need to mine and process virgin materials, and energy and
greenhouse gas benefits. EPA finds these potential benefits compelling
and is therefore revising the closure requirements in the rule to
accommodate the removal and beneficial use of CCR. EPA has therefore
revised the rule to provide that closure of an otherwise idled CCR unit
is not immediately triggered, as long as the owner or operator is
removing substantial quantities of CCR from the unit. However, once
removal of CCR for beneficial use is no longer taking place, the rule
would require the owner or operator to initiate closure of the CCR
unit. See Sec.  257.102(e)(1) and (e)(2) in the rule.
    After considering comments received regarding the specific
timeframe by which closure must be initiated following known final
receipt of wastes, the Agency is finalizing the 30 day timeframe from
the proposed rule. Several commenters expressed concern that 30 days is
too short because it does not account for the potential that weather or
seasonal concerns may interfere or cause substantial delay. The Agency
acknowledges that weather or seasonal effects can delay certain
activities, but disagrees that the rule provision needs to be revised
to account for those. This provision does not require that specific
actions or activities must be initiated during this 30-day period. For
example, the rule does not require the installation of the final cover
system (or the commencement of removal of CCR from the CCR unit)
necessarily begin within this 30-day period. Instead, the provision is
more flexible; the owner or operator can initiate closure by taking
other actions necessary to implement the closure plan that are not
weather or seasonal dependent, such as turning off pumps supporting
sluice lines or taking any steps necessary to comply with any state or
other agency standards that are a prerequisite to initiating closure.
Provided the owner or operator has started to take the measures to
implement the closure plan that can be feasibly undertaken, the
facility will have complied with this requirement.
    The 30-day period remains equally appropriate under the wider
provision that allows closure to be triggered either by the known final
receipt of all wastes in the unit, or upon the known final volume
removal of CCR for beneficial use of CCR. There are no facts unique to
these circumstances that would necessitate an extension beyond the 30
day timeframe. Furthermore, as the terms ``known final receipt'' and
``known final volume removal'' suggest, the owner or operator has made
the determination to cease managing waste in the CCR unit, or to cease
removing CCR from the CCR unit for beneficial use purposes. This will
likely occur in situations where the CCR unit is reaching its disposal
capacity (or treatment capacity when the CCR unit is receiving non-CCR
waste streams) or the

owner or operator intends to close the CCR unit for other purposes
(e.g., the closing of a CCR surface impoundment following conversion to
dry handling of CCR). Given that these situations can generally be
anticipated and planned for in advance, EPA is not aware of
circumstances that would prevent owners or operators from at least
commencing closure within this 30-day period. In summary, the owner or
operator must commence closure of the CCR unit with 30 days of known
final receipt of CCR or any non-CCR waste stream, or within 30 days of
known final removal of CCR for beneficial use, whichever date is later.
ii. Temporarily Idled Units
    This situation involves CCR units with remaining CCR disposal or
storage capacity (or treatment capacity for non-CCR waste streams) that
may sit idle for extended periods of time (e.g., potentially years at a
time); however, the owner or operator intends to continue to maintain
the idled unit to receive CCR or non-CCR waste streams in the future.
EPA proposed that these CCR units could remain idle for up to one year,
but that closure of the CCR unit would have to be initiated no later
than one year after the most recent receipt of CCRs. See 75 FR 35252
(proposed Sec.  257.100(j)). The majority of commenters claimed that
one year was too short and would require the premature closure of CCR
units that would be needed in the future. In response to these comments
and new information documenting examples of legitimate circumstances in
which CCR units were idled for more than one year, EPA solicited
comment on a revised approach to establish longer timeframes to
initiate closure for temporarily idled CCR units. As discussed
previously, this approach entailed establishing a rebuttable
presumption that if the CCR unit has not received waste within a
specified period of time (i.e., 18 months to two years), the CCR unit
would be considered inactive and closure of the CCR unit would be
required. However, this time could be extended beyond the 18 months or
two years if the facility could substantiate certain findings. See 78
FR at 46945.
    After considering comments received, the Agency is essentially
finalizing the approach presented in the 2013 NODA. Specifically, in
situations where the CCR unit has remaining disposal or storage
capacity (or treatment capacity for non-CCR wastestreams) and there is
a reasonable likelihood that the CCR unit will receive additional CCR
or non-CCR waste in the future, the final rule allows the owner or
operator to keep the CCR unit available for use for up to two years.
However, if the CCR unit has not received CCR or any non-CCR waste
within two years of the last receipt of CCR or any non-CCR waste,
whichever date is later, the rule requires closure of the CCR unit
unless the owner or operator can document that additional time is
necessary to accommodate routine operations and legitimate waste
management activities.
    The Agency agrees that it is not necessary to require closure of
temporarily idled CCR units after one year. Information in the record
documents numerous examples of legitimate circumstances in which CCR
units were idled for more than one year. In most of the examples
provided CCR units are temporarily idled for periods that can last more
than one year, but typically use of the CCR units resumes within
approximately two years. Based on this information EPA has concluded
that a two year timeframe before presumptively requiring closure of a
CCR unit would be more consistent with current practice, and is better
supported by the available information.
    This same information documented that there can be situations in
which a CCR unit is idled for longer periods of time (e.g., a coal-
fired boiler may be idled for years during which another fossil fuel is
burned (e.g., natural gas), and the CCR unit will be needed when the
utility returns to coal burning. In order to obtain additional time
beyond two years, the owner or operator must document in writing both
that the CCR unit has remaining disposal or storage capacity and the
facts that support a conclusion that there is a reasonable likelihood
that the CCR unit will accept CCR or non-CCR waste in the foreseeable
future. The facility would need to substantiate those findings,
including the specific reasons the owner or operator believes ``that
there is a reasonable likelihood that CCR will be disposed in the waste
disposal unit.'' These findings would need to be certified by the owner
or operator of the CCR unit.
    The rule identifies examples of specific scenarios that would
support a determination that there is a continuing need for the unit to
support future waste management activities (e.g., that the CCR will
resume receiving CCR or non-CCR waste in the future). These are
intended to be illustrative rather than an exclusive list; there may
well be additional circumstances in which routine operations or
legitimate waste management practices would support the necessary
determination. The particular situations identified in the rule
generally match those discussed in the NODA or reflect situations
identified in public comments. Specifically, the rule identifies four
particular circumstances: (1) Normal plant operations include periods
during which the CCR unit does not receive wastes (CCR or non-CCR waste
streams). This may include the alternating use between one CCR unit
that receives CCR while dewatering or removing CCR from a second unit.
(2) The CCR unit is dedicated to a coal-fired boiler unit that is
temporarily idled (i.e., CCR is not being generated) and there is a
reasonable likelihood that the coal-fired boiler will resume operations
in the future. (3) The CCR unit is dedicated to an operating coal-fired
boiler (i.e., CCR is being generated); however, no CCR is being placed
in the CCR unit because the CCR is being entirely diverted to
beneficial uses, but there is a reasonable likelihood that the CCR unit
will again be used in the foreseeable future. (4) The CCR unit
currently receives only non-CCR waste streams and those non-CCR waste
streams are not generated for an extended period of time, but there is
a reasonable likelihood that the CCR unit will again receive non-CCR
waste streams in the future. As noted, a facility must substantiate
these findings; it is not sufficient to merely repeat the words of the
regulation and conclude that additional time is warranted.
    The final rule allows an owner or operator to obtain additional
two-year time extensions for as long as the owner or operator continues
to be able to provide a factual basis to justify the need for
additional time via a written demonstration. Because these idled units
must continue to comply with all applicable technical requirements,
including those for groundwater monitoring, corrective action, and
structural stability, a fixed or definitive limit on the amount of time
that a CCR unit can sit idle is not necessary.
    In addition, the Agency agrees that the final rule should better
define the actions or activities that constitute ``initiation of
closure'' of a CCR unit. A clear definition will assist in the
implementation and understanding of the rule. Commenters suggested a
number of actions or activities, any one of which would be sufficient
to show that closure of the CCR unit has been initiated. Examples
provided by the commenters included the removal of CCR sluice lines;
beginning the necessary permitting processes (i.e., submitting a
completed permit application); turning off pumps supporting the sluice
lines; preparing a bid for contractors; or procuring capping materials
such as clay or top soil.

    The final rule specifies that closure has been initiated when the
owner or operator takes two actions. The first action is that the owner
or operator must have permanently ceased placing CCR and non-CCR waste
streams in the CCR unit. As suggested by commenters, permanent removal
of CCR sluice lines or inactivation of the pumping system supporting
the sluicing operation would be evidence that placement of CCR and non-
CCR waste streams has ceased. The second action is that the owner or
operator must have taken steps to implement the written closure plan
required by the rule. This second action would include submitting a
completed application for any required state or agency permit or permit
modification in order to implement closure of the CCR unit, or taking
any steps necessary to comply with any state or other agency standards
or regulations that are a prerequisite to initiating or completing the
closure of the CCR unit. Once the owner or operator has completed both
of these actions, closure of the CCR unit has been initiated for
purposes of this rule. See Sec.  257.102(e)(3) in this rule.
iii. Closure for Cause
    Finally, the Agency is clarifying that the closure initiation
timeframes specified above--the 30 day period for known final receipt
or known final volume removal and the 2 year period for temporarily
idled CCR units--do not apply to closures initiated for cause. As
discussed elsewhere in the preamble, the final rule requires certain
CCR surface impoundments and CCR landfills to close. The situations
include: Unlined CCR surface impoundments whose groundwater monitoring
shows an exceedance of a groundwater protection standard; existing CCR
surface impoundments that do not comply with the location criteria; CCR
surface impoundments that are not designed and operated to achieve
minimum safety factors; and existing CCR landfills that do not comply
with the location criteria for unstable areas. In these situations, the
final rule specifies that the owner or operator must initiate closure
activities within six months of making the relevant determination that
the CCR unit must close.
b. Deadlines To Complete Closure
    In response to the August 2013 NODA, many utility commenters stated
that the time period to complete closure must be sufficiently flexible
to account for the inherent uncertainties in predicting a closure
schedule. These commenters pointed to potentially innumerable
complications and circumstances beyond the control of the owner or
operator that render it nearly impossible to predict with precision
when the closure of a CCR unit will be completed. These commenters also
believe it is impractical and unrealistic for the rule to subject the
closure of CCR units to any type of fixed regulatory structure. They
maintained their position from the proposed rule that it would be
impossible to properly complete closure of most CCR surface
impoundments within 180 days. Their recommendation is to allow closure
timeframes to be governed by the a state-approved closure process,
which would include the owner or operator developing and submitting a
closure plan to the state and mechanisms for the state to verify and
enforce compliance with all closure requirements, including the closure
plan. Under this approach, the owner or operator's compliance with the
requirements of the state-approved closure process (including following
the closure plan, completing mitigation, etc.) would represent
compliance with this rule's closure requirements. For CCR units not
subject to a state-approved closure process, these commenters
recommended that the owner or operator should demonstrate compliance
with the CCR closure requirements by submitting a closure plan to the
state that is certified by an independent professional engineer. In
this case, because there is not direct state oversight and
administration of the closure process, the timelines in the closure
plan could be subject to a modified set of tiered timeframes for
completing closure, provided owners or operators could demonstrate that
more time is needed to close the unit on a case-by-case basis.\122\
These commenters also opposed any closure approach with firm and
inflexible timeframes because no single factor (e.g., the acreage of
the CCR unit or the volume of CCR in the unit) is determinative in all
instances of how long it will take to complete closure of the CCR unit.
Commenters also cautioned that pre-closure closure plans (and the
closure schedules contained therein) may not be an actual reflection of
the time it will take to close the unit due to unforeseen or variable
conditions. Finally, these commenters also generally opposed the idea
discussed in the NODA of petitioning the Agency for a site-specific
rule to vary from a generally applicable deadline.
---------------------------------------------------------------------------

    \122\ The tiered timeframes for completing closure could be
based on the size of the CCR unit (after obtaining necessary state
and local approvals): (1) Within 3 years for an impoundment with an
area less than 20 acres; (2) Within five years for an impoundment
between 20 and 50 acres; (3) Within 8 years for an impoundment
between 50 and 75 acres; (4) Within 10 years for an impoundment with
an area of 75 acres or more; and (5) Within 180 days for a landfill.
Under this approach, the owner or operator could demonstrate the
need for additional time to close the CCR unit.
---------------------------------------------------------------------------

    Many commenters described the numerous factors that could affect
timeframes for closure of a CCR unit. Most comments were specific to
CCR surface impoundments where closures are typically more complex as
compared to CCR landfills due to the presence of water in impoundments.
Factors most often cited by the commenters that may affect the time
required to close a CCR unit included: (1) The size and volume of CCR
in the unit; (2) the geotechnical characteristics of the CCR; (3) the
type or design of the surface impoundment (i.e., diked, incised, valley
fill, and side hill); (4) the need to coordinate or obtain approvals
from state permitting officials; (5) the availability of qualified
engineers, contractors, and materials since closing a CCR unit is a
specialized activity, especially given that many units may be required
to close simultaneously; (6) climate and weather that can affect
dewatering operations and the length of a construction season; (7) the
time needed to obtain replacement disposal capacity for a closing unit
that would ensure ongoing facility operations; and (8) dam safety
considerations during closure. Many of commenters identified that the
dewatering process (an early necessary step in the closure process) as
being a site-specific issue, as the time that will be needed to dewater
an impoundment can vary considerably depending on the type of CCR unit,
the volume of CCR in unit, and the geotechnical properties of the CCR.
Several commenters also cited that closure times for some CCR units
will require substantial volumes of fill material to properly grade a
closing surface impoundment to facilitate positive drainage from the
closed unit. These commenters provided estimates on the volumes of fill
material needed and showed that the earthmoving aspect of this step
alone can take many years to complete in some cases.
    Several state commenters generally supported the tiered closure
alternative discussed in the NODA. However, these commenters urged EPA
to include provisions in the rule to provide flexibility for closing
units to demonstrate the need for additional time on a case-by-case
basis.
i. Timeframes for Completing Closure
    In the August 2013 NODA the Agency solicited comment on ways to
establish categories of timeframes that would adequately account for
the various factors that can affect the amount of

time needed to properly close a CCR surface impoundment. One approach
discussed in the NODA was called the ``tiered approach'' that was based
on comments received in response to the proposed rule. Under that
approach, the final rule would establish fixed timeframes to complete
closure that varied depending on the size of the impoundment (i.e.,
surface area acreage). The Agency stated in the NODA that the concept
of a tiered approach was appealing; however, the precise basis for the
distinctions (i.e., unit size cutoffs) and timeframes were not clear.
EPA further explained its concern that factors other than size (e.g.,
climate, geography, unit configuration) would also appear to be
relevant, and that any timeframes should account for those other
factors. EPA encouraged commenters interested in supporting a tiered
approach to provide the rationale and data to support any suggested
categories of timeframes. 78 FR 46946. Most commenters opposed the
tiered approach by itself (i.e., an approach without an accompanying
process by which an owner or operator could obtain additional time due
to site-specific circumstances) because they felt there simply are too
many factors that can affect closure timeframes. These commenters
concluded that basing closure timeframes on a subset of factors would
not be appropriate. As one commenter noted, a 20 acre impoundment 10
feet deep can likely be dewatered and closed more quickly than a 20
acre impoundment 30 feet deep.
    After considering comments and information available on closure
timeframes, EPA has concluded that there are insufficient data and
information to adopt the kind of tiered approach discussed in the NODA.
EPA is convinced that the available information does not support an
approach that would establish fixed and definitive timeframes for
closure, based on a select subset of factors that distinguish between
surface impoundments (e.g., a 50 acre diked impoundment holding 500
acre-feet of CCR with a hydraulic conductivity of 1 x 10-5
centimeters per second located in a state in the southwest with a
permitting program would be required to close in four and one-half
years, while a 50 acre cross valley impoundment holding 1,500 acre-feet
of CCR with a hydraulic conductivity of 1 x 10-6 centimeters
per second located in a state in the upper midwest with a permitting
program would be required to close in seven years, etc.). While
information is available for surface impoundments on certain factors,
such as the size and type of the unit and geographic information, the
Agency has little to no data for a number of other key factors. For
example, EPA has no information on the geotechnical properties of the
CCR that can affect the time needed to dewater a unit, the volumes of
clays, soils, and other materials that will be needed for closure, and
information on the time needed to obtain state approvals (in accordance
with state CCR programs) related to closure of a unit.
    In discussing the tiered approach EPA noted that commenters had
suggested that the largest CCR surface impoundments (i.e., those having
a surface area greater than 75 acres) should be subject to a site-
specific deadline to complete closure. In the NODA, the Agency
explained that a site-specific deadline may not be practicable unless
the rule were to establish a ``variance'' process as part of the rule.
78 FR 46946. Under a variance approach, EPA would establish a specific
deadline (e.g., closure must be completed no later than five years from
the date closure activities are initiated), but would allow facilities
to petition EPA for a site-specific rule to establish an alternate
deadline. In response to the NODA, some commenters expressed interest
in such an approach, but other commenters found the approach not
practicable since each owner or operator would need to petition the
Agency for a site-specific rule. Some commenters believed that a site-
specific rule process, which would necessarily involve a notice and
comment process, would be an unwieldy process leading to unnecessary
delays. The Agency agrees that this is also not a practical alternative
to establish timeframes to complete closure.
    Recognizing the numerous factors that can affect the amount of time
needed to close an impoundment, many commenters suggested EPA not
establish any type of fixed regulatory deadline for closure. Instead,
these commenters recommended that the rule allow closure timeframes to
be governed by a state-approved closure process. Under this process
suggested by commenters, an adequate state-approved closure process
would include one where the owner or operator developing and submitting
a closure plan to the state and mechanisms for the state to verify and
enforce compliance with all closure requirements, including the closure
plan. Under the commenter's recommendation, compliance with the
requirements of the state-approved closure process would not be
compliance with the closure requirements of this rule. As discussed
elsewhere in this preamble, under subtitle D of RCRA, the Agency cannot
rely on the existence of a state permitting authority to implement the
subtitle D requirements.
    Some other commenters suggested EPA not establish any type of fixed
regulatory deadline for closure in the rule, and instead rely on the
closure plan developed and certified by a professional engineer. The
Agency disagrees that this approach would meet the protectiveness
standard of RCRA section 4004(a). CCR units present significant risks,
and it is critical that facilities complete closure expeditiously--
particularly those that are closing because they are structurally
unsound or are contaminating groundwater. To be able to determine that
the rule will be protective, the final rule must limit the discretion
of individual facilities, many of whom may have significant incentives
for delay, and avoid the potential for abuse. Moreover, in contrast to
corrective action, where EPA was truly unable to establish an outer
limit on the necessary timeframes--including even a presumptive outer
bound--closures, while complex, do not vary to the same degree as site
remediation actions. Consequently, as discussed later in this section,
the available data were sufficient to support the establishment of
definitive timeframes.
    Most commenters, however, were generally supportive of an approach
that would establish timeframes for closure, whether in a tiered-like
approach (i.e., timeframes for closure based on one or more
characteristics of the unit) or under a ``rebuttable presumption''
approach, so long as the rule would provide the owner or operator a
process or procedures to demonstrate the need for additional time. As
explained in the NODA, such an approach could be implemented by
establishing a presumption that facilities complete closure within a
specified timeframe, such as five years, unless the facility could
document that closure is not feasible to complete within the
presumptive timeframe.
    After consideration of all of the public comments, EPA is adopting
an approach that takes elements from two of the alternatives discussed
in the NODA: The concept of tiered timeframes based primarily on the
size of the surface impoundment, and the concept of a rebuttable
presumption. The final rule establishes a presumption that the owner or
operator must complete the closure of a CCR surface impoundment within
five years of initiating closure activities. For CCR landfills the
presumption is that the owner or

operator must complete closure within six months of initiating closure
activities. The rule, however, provides procedures for an owner or
operator to rebut either presumption and obtain additional time,
provided the owner or operator can make the prescribed demonstrations.
For CCR surface impoundments, the amount of additional time beyond the
five years varies based on the size (using surface area acreage of the
CCR unit as the surrogate of size) of the unit. For impoundments 40
acres or smaller, the maximum time extension is two years. For
impoundments greater than 40 acres, the maximum time extension is five
two-year extensions (ten years) and the owner or operator must
substantiate the factual circumstances demonstrating the need for each
two year extension. For a CCR landfill, the amount of additional time
beyond the six months does not vary according to the size of the
landfill, rather the maximum time extension is two one-year extensions
(two years) for any CCR landfill. The owner or operator must
substantiate the factual circumstances demonstrating the need for each
one-year extension.
ii. CCR Surface Impoundment Timeframes
    To develop these timeframes the Agency began by identifying the
period of time in which most surface impoundments could feasibly
complete closure. EPA intended this period of time to serve as the
basis for the rebuttable presumption of the rule. As EPA recognized in
the NODA, a timeframe that would be feasible for the largest units
would grant more time than could be justified to complete the closure
of smaller units. The closure of CCR units, and particularly the
closure of CCR units that are compelled to close because they fail to
comply with the rule's requirements (e.g., are structurally unstable or
are contaminating groundwater), needs to occur as expeditiously as is
feasible. While these units (and particularly the larger CCR surface
impoundments) are in the process of closing, they continue to present
risks to human health and the environment. On the other hand a
presumptive time period that is feasible for a small percentage of
units would simply result in a greater number of facilities that would
need to obtain time extensions. It is well established that the law
cannot compel actions that are physically impossible, ``lex non cogit
ad impossibilia,'' and it is incumbent on EPA to develop a regulation
that does not in essence establish such a standard.
    The available information shows that CCR surface impoundments can
vary in size by orders of magnitude (i.e., from less than one acre to
nearly 1,000 acres). EPA evaluated the information on the size
distribution of CCR surface impoundments in its database of survey
results from EPA's 2009 Information Request.\123\ Through this effort,
EPA received a substantial amount of factual information from 240
facilities covering 676 surface impoundments, including surface area
information on over 650 impoundments. The database of survey responses
shows that the median surface impoundment is approximately 14 acres in
size, 75 percent of impoundments are 50 acres or smaller, 80 percent of
impoundments are 66 acres or smaller, and 90 percent of impoundments
are 111 acres or smaller.
---------------------------------------------------------------------------

    \123\ More information on EPA's Information Request, including a
data base of survey responses, can be accessed at http://www.epa.gov/epawaste/nonhaz/industrial/special/fossil/surveys/index.htm.
---------------------------------------------------------------------------

    Available information on actual and projected timeframes needed to
close CCR surface impoundments of varying sizes (using surface area as
the surrogate for size) is summarized below. Much of this information
came from public comments from utilities. The largest CCR surface