Attach 2 - DEQ Position regarding Duke Energy's Proposed Revisions CAP Guidance FINAL

North Carolina Department of Environmental Quality's (NCDEQ's) Review Position concerning:
Attachment 2
Supporting Rationale for Proposed Interpretation and Adjustments to the
Corrective Action Plan Content Guidance (NCDEQ April 2018) by
Duke Energy January 2019
CAP Guidance
Duke Energy's
DEQ's Position regarding
Section*
Rationale for Proposed Adjustments
Duke Energy's Proposed
Adjustments
Executive Summary
• Added Executive Summary to provide a
Acceptable.
high-level summary of the Corrective Action
Plan's (CAP) conceptual site model (CSM)
and the site -specific corrective action
approach proposed based on the CSM.
1. INTRODUCTION
1.C.b.
• Deleted text referring to the Notice of
Deleting text concerning the
Regulatory Requirements (NORR). These
NORR in the section is not
NORR requirements are focused on the
acceptable and related content
Comprehensive Site Assessments (CSAs) and
must be reflected in the CAP.
are not directly relevant to the CAP.
The information in the NORR
required by rule was not
provided in a complete manner
in the CSA documents;
whereas, the information in
the letters generated by the
Regional Offices identified
what is needed. This
information was not provided
in previous submittals and shall
be included in the CAPS.
1.D
• Added text to clarify that the CAP will
The proposed additional text is
provide a general written description of how
acceptable; however, the
these items were considered during the CAP
criteria that will be used for
preparation process per 02L .0106(i). This is
evaluation and selection of
also intended to clarify that the criteria
remedial alternatives in the
provided in Section 7.D.a.iv.1-10 will be used
CAPS should be provided in
for evaluation and selection of remedial
Section 6.
alternatives in the CAPS.
July 29, 2019

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CAP Guidance
Duke Energy's
DEQ's Position regarding
Section*
Rationale for Proposed Adjustments
Duke Energy's Proposed
Adjustments
1.E.b.
• Added text to clarify that only non -coal
Acceptable. Acknowledge and
waste streams that may affect the
identify other primary and
subsurface conditions at or proximate to
secondary sources present that
coal ash basins or coincident source areas
are not under the jurisdiction
will be included to maintain focus on the
of CAMA. Provide DEQ Division
Coal Ash Management Act requirements.
oversight and Incident Number
if relevant.
2. RESPONSE TO COMPREHENSIVE SITE ASSESSMENT UPDATE COMMENTS IN SUPPORT OF CAP
DEVELOPMENT
2. and 2.13.
• The note at the top of the section clarifies
Acceptable. Revised
how responses to the NCDEQ CSA comment
interpretations of site
letters will be addressed in the CAP to
conditions that address
facilitate the NCDEQ's review. Modification
Department concerns
to the text in Section 2.13.a.&b. has been
identified in the CSA comment
revised to reflect this approach.
letters shall be provided in the
documents to support
determination of appropriate
remedial alternatives.
3. OVERVIEW OF SOURCE AREAS BEING PROPOSED FOR CORRECTIVE ACTION
Added a note that describes the role of ash
Acceptable.
basin decanting and ash basin closure plans
as source removal/control methods that are
linked to the groundwater corrective action
plan for each site. Duke Energy will add a
discussion of the source control measures
(the approved Closure Plan) and the benefits
to groundwater restoration and integration
into the corrective action program.
3.A.
• Added reference to the NCDEQ letter
Acceptable.
providing the list of sources for each site to
be addressed in CAP.
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019

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CAP Guidance
Duke Energy's
DEQ's Position regarding
Section*
Rationale for Proposed Adjustments
Duke Energy's Proposed
Adjustments
3.B.
• Revised text to reference NCDEQ letter
Acceptable.
providing list of sources for each site that
will be addressed in subsequent and
separate CSAs.
• Previously numbered items a, b, c are no
longer needed due to the clarification
provided by the NCDEQ's letter and were
deleted.
4. SUMMARY OF
BACKGROUND DETERMINATIONS
4.B.
• Added text to provide discussion of
Acceptable. However, site -
regional background concentrations for
specific background data
similar geologic settings as context for soil
collected proximal to the
background Threshold Values (BTVs).
subject facilities are the basis
for corrective action decisions.
4.C.
• Added text to provide discussion of
Acceptable. However, site -
regional background concentrations for
specific background data
similar geologic settings as context for
collected proximal to the
groundwater BTVs.
subject facilities are the basis
for corrective action decisions
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019

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CAP Guidance
Section*
Duke Energy's
Rationale for Proposed Adjustments
DEQ's Position regarding
Duke Energy's Proposed
Adjustments
4.D.
• Revised text to indicate that referenced
This proposed change is not
EPA values are recommended "criteria". EPA
acceptable since application of
Nationally Recommended Water Quality
EPA NRWQC by DEQ is
Criteria for Aquatic Life & Human Health
authorized in the context of
(EPA NRWQC) have not been universally
using narrative regulations for
adopted under 15A NCAC 02B. Sample
toxic controls where no surface
results will be compared to those criteria
water quality standard has
found in 15A NCAC 02B .0211(11) with
been adopted into state
values for EPA NRWQC provided for
regulations. This is consistent
reference.
with state authority under
Clean Water Act directives as
well as state administrative
code with respect to corrective
action.
Stream segments near samples
that exhibit exceedances or
that demonstrate impacts
attributable to coal ash should
be evaluated for potential
groundwater/ surface water
discharge and appropriate
remedial measures shall be
considered for corrective
action.
Direction concerning
evaluation of 15A NCAC 2B
standards was provided in an
email from Eric Smith to John
Toepfer on July 19, 2018. The
process for evaluating state
water quality standards,
criteria, and protective values
should be followed as
described in the website
regarding 15A NCAC 02B
surface water standards:
https://deg.nc.gov/nc-
stdstable-09222017
DEQ will work with Duke
Energy to determine the
appropriate response to
exceedances of the 15A NCAC
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019

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CAP Guidance
Duke Energy's
DEQ's Position regarding
Section*
Rationale for Proposed Adjustments
Duke Energy's Proposed
Adjustments
02B surface water quality
standards where applicable.
Removed Section - SUMMARY OF POTENTIAL RECEPTORS
• Removed this section and consolidated
Acceptable. Note that since the
potential receptor information into Section
hydraulics and
6.13. This will avoid presenting redundant
groundwater/surface water
information.
flow patterns near the ash
basins have changed over the
years, all areas that may have
been impacted should be
considered with respect to
potential receptors.
5. CONCEPTUAL SITE MODEL (CSM) — New Section
• Placed CSM into a more prominent
Acceptable. A figure that
position in the guidance document to
illustrates groundwater
emphasize the importance of the CSM to
impacts with a 3-dimensional
support corrective action decision -making.
perspective should be included
All elements from Section 6.A.b.i. were
as part of the revised CSM.
included along with additional items to
make the CSM more robust.
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019

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6. SOURCE AREA 1
6. Opening Section
• Paragraph 1 - Deleted text referring to
Overall, the proposed changes
Paragraphs
discussions with regional DWR office to
to the text are acceptable.
identify source areas. This item was resolved
However, observations
by NCDEQ letter identifying source areas.
concerning proposed changes
These sources will be considered for
to specific paragraphs include:
corrective action based on the results of the
site assessments currently in progress.
Concerning proposed text
revision in Paragraph 3, note
• Paragraph 3- Edited text to identify water
that since the hydraulics and
supply wells and surface water features
groundwater/surface water
hydraulically downgradient relevant to
flow patterns near the ash
Source Area 1 to focus only on those areas
basins have changed over the
that could potentially be affected to
years, all areas that may have
facilitate the corrective action
been impacted should be
preparation process. The CAP will provide
considered with respect to
justification for selection of water supply
potential receptors.
wells and downgradient surface water
features relevant to each source area.
Concerning proposed text
revisions in Paragraph 4, while
• Paragraph 4 - Added text to define
the definition of COI presented
constituents of Interest (COls) for corrective
is consistent with15 NCAC 02L.
action. This is consistent with 15 NCAC 02L.
0106(e)(4) corrective action
0106(e)(4) corrective action requirements to
requirements, any constituent
address constituents with concentrations
identified by the Department
greater than 2L applicable values at or
that has migrated across, or
beyond the compliance boundary. This
has potential to migrate across,
approach will focus the information
the compliance boundary shall
presented and the corrective action to the
be considered as part of any
constituents exceeding the applicable
remedial design. This concept
standard (2L/IMAC/BTV) at the relevant
shall be reflected in the CAPS.
point of compliance.
Refer to requirements related
to 2L .0107(k).
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019

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6.A.a
• Added text to reduce representing data
Not acceptable. This proposed
previously provided to NCDEQ with the
change is problematic since a
intent of leaving more time to focus on
complete and defensible data
corrective action analysis.
set was not provided in the
past. Sufficient data must be
included to justify any
proposed corrective action.
Duke may not rely on
previously submitted data to
justify such proposed
corrective action. Additionally,
consensus concerning which
Cols to analyze for corrective
action must be reached
between Duke Energy and the
respective Regional Offices.
The data needed to address
NCDEQ CSA Update comments
shall be provided in the body of
the CAP. In summary, the
Department does not believe
that all data have been
provided in a comprehensive
manner at this time to
adequately evaluate site
conditions and refine remedial
design to facilitate decision
making regarding corrective
action. Also, providing data or
responses to CSA Update
comments only in an appendix
is not acceptable.
6.A.a.v
• Revised text to remove the reference to
Acceptable.
the calculation of specific storage. Specific
storage is a general aquifer parameter that
represents the amount of groundwater per
unit volume of a saturated formation that is
lost or gained from storage due to the
compressibility of the mineral framework
that comprises the formation and the pore
water per unit change in head rather than
being used to evaluate COls in groundwater.
The groundwater flow and transport model
will estimate the COI concentrations over
time for the evaluation of remedial
alternatives. This approach provides a more
meaningful representation of the
performance of the remedial alternatives
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019

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over time compared to a calculation of
specific storage.
6.A.a.vi.1.
• Added Ash Leachate Environmental
Acceptable.
Assessment Framework (LEAF) sample data.
6.A.a.vi.3
• Added text to allow for figure preparation
The overall concept of
flexibility such as the use of exceedance
flexibility with respect to figure
ratio maps and including the surrounding
generation for the CAPs is
area.
acceptable, but the specific
constituents that will be
mapped in the documents shall
be determined by consensus
with the DEQ Regional Offices.
The Department acknowledges
that the isolated and irregular
spatial distribution exhibited by
some constituents does not
translate well to the
conventional illustration of
groundwater plumes.
Consideration of constituents
that will be mapped in the
CAPs shall be based on a
review of site factors that
affect flow and transport,
including geochemical
conditions, as well as what is
needed to explain site
conditions and risk to the
public. Duke Energy should
initiate dialogue with the DEQ
Regional Offices to facilitate
agreements concerning
constituents that will be
mapped in the CAPs.
6.A.a.vii
• Revised text to indicate "other source
Acceptable.
material", if any, will be addressed based on
the results of the additional source area
assessments currently underway.
6.A.b.
• Added text to clarify that the discussion
Acceptable. The June 2019 cut -
regarding the extent of COls will include
off date for inclusion of data
data collected through June 2019. This will
into a CAP is acceptable for
provide Duke Energy with the needed time
sites where document
to reduce site data and include it in the
submittals are scheduled for
interpretation of site conditions.
December 2019. However,
CAPs due at later dates should
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019

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will have different data cut-off
dates based on Duke Energy's
internal review process.
6.A.b.i.1-6.
• Removed text to the newly created
Acceptable.
Section 5 above to place greater emphasis
on the CSM.
6.A.b.ii.
• Added text that COI results presented are
This proposed change is not
to be based on consideration of geometric
acceptable since any 2L
mean concentrations and/or time vs.
Standard exceedances
concentrations relationships based on
detected at a site are relevant
historical data collected through June 2019.
and should be acknowledged
This approach will provide more appropriate
and discussed. Discussions
concentration results for corrective action
concerning specific COls that
planning by eliminating anomalous or
will be considered for
inconsistent data likely associated with
corrective action will
transient geochemical variations.
commence on March 15, 2019.
See time -frame reference with
respect to data that shall be
incorporated into the
documents in response to
proposed 6.A.b. text changes.
6.A.b.iii.1.6.
• Eliminated table of analytical results for
Acceptable.
supply wells in this section since the same
information is requested in Section B.b.ii. to
eliminate redundant information.
6.A.c.i-ii.
• Removed this section since very similar
Not acceptable. Do not
information is requested in Section 6.D.a.i-ii
remove. Keep the section and
which is more focused on corrective action
provide a list of COls for each
analysis.
area that require corrective
action.
6.A.c.i-ii.
• Added to text to clarify that
Acceptable.
isoconcentration maps will be included for
COls identified for remediation.
6.A.e.
• Changed section title from Plume
Acceptable.
Characteristics to COI Distribution in
Groundwater to reflect the fact that not all
inorganic COls behave as a "plume" and are
often isolated and/or transient due to
geochemical conditions.
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019

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6.a.e.i.1.
• Revised text to say 'stable' to expanding'
Acceptable.
rather than 'moving' and (or) expanding
since 'moving' is very similar
to expanding. This wording is also consistent
with NCDEQ and USEPA MNA guidance
concerning the description of plume
behavior.
6.a.e.ii.1.
• Revised text to provide a general
Acceptable. Provide content
discussion of site geochemical conditions in
that was directed in the CSA
the body of the CAP recognizing
Update document comments.
that the detailed geochemical items listed
will be included in the geochemical
modeling report which will be presented
in the appendices.
6.B.a
• Revised text to clarify that only those
Acceptable. Note that since the
surface waters that are hydraulically
hydraulics and
downgradient that could be affected by
groundwater/surface water
site -related COls will be identified on the
flow patterns near the ash
map to maintain focus on those areas that
basins have changed over the
may need to be addressed under the CAP.
years, all areas that may have
been impacted should be
considered with respect to
potential receptors.
6.B.b.
• Revised to provide clarity regarding
Acceptable.
identification of water supply wells.
6.D.a.i.1.
• Removed text regarding a 3-dimensional
Acceptable.
(3-D) map. A 3-D block diagram figure will be
included as part of the CSM.
6.D.a.iii.
• Removed this section on predictive
Not acceptable. Keep this
modeling. Duke Energy proposes to
section and provide a succinct
consolidate this section into the
summary of modeling results.
groundwater modeling report that will be
presented as an appendix to the CAP. The
groundwater modeling will be used to
inform corrective action decision -making.
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019

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6.E.b.
• Added text to indicate information
Acceptable. Provide enough
requested will be provided at conceptual
information and detail for the
design level.
various remedial alternatives
considered to facilitate review.
A higher level of cost detail
shall be provided for the
remedial alternative selected in
order than others considered
to provide adequate
information for decision
making. Otherwise, additional
documentation may be
required before an alternative
is approved.
6.E.b.iv.
• Added "approximate" to costs since
See comments above
information will be at conceptual level.
concerning Section 6.E.b.
10. MAPs AND FIGURES
• Added note that describes Duke Energy's
Acceptable. Isoconcentration
approach for figures to be included in the
maps shall provide mapping of
CAP with an emphasis on
analytical results to
making the CAP more manageable on a
background or non -detect
practical basis and focusing on those figures
levels to depict concentration
necessary to support our corrective action
gradients related to COI
approach.
distribution. In addition, all
data points must be illustrated
on maps. This level of detail is
needed to evaluate remedial
design and address CSA Update
document comments.
11. APPENDICES
Added a general planned list of CAP
Acceptable. Final content
appendices to clarify what will be included
should be based on a
in the CAP deliverables. The
consensus developed between
appendices may be adjusted on a site-
Duke Energy and the respective
specific basis as needed.
DEQ Regional Offices and
should include all supporting
documentation for remedial
alternative design.
*Refers to the proposed revised CAP guidance section and supporting rationale provided in
Attachment 2 of Duke Energy Interpretation of Corrective Plan Content Guidance Provided by the
North Carolina Department of Environmental Quality January 23, 2019
DEQ Position Duke Energy's Proposed CAP Guidance Revisions January 2019