Duke CAP Contents Guidance Letter 9-10-19

ROY COOPER
Governor
HCHAEL S. REGAN
Secretory
LINDA CULPEPPER
Director
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
NORTH CAROLINA
Envkmmental Qual ty
September 10, 2019
Subject: Duke Energy Interpretation of Corrective Action Plan Content Guidance (January 23,
2019) — North Carolina Department Environmental Quality Response and Conditional
Approval
Dear Mr. Draovitch:
On January 23, 2019, the North Carolina Department of Environmental Quality's (DEQ) Division of Water
Resources (DWR) received the Duke Energy Interpretation of Corrective Action Plan (CAP) Content
Guidance Provided by the DEQ. That document describes Duke Energy's proposed approach for preparing
the groundwater CAPS within the structure of the DWR's guidance titled "CAP Content for Duke Energy
Coal Ash Facilities" dated April 27, 2018. DWR has reviewed the proposed approach regarding CAP
development and conditionally approves its implementation with the following considerations and
conditions: In addition, DWR has provided the attached comments on Duke Energy's Supporting Rationale
for the Proposed Interpretations and Adjustments to the CAP Content Guidance that was produced with
respect to the April 27, 2018 letter (Attachment 2).
• Section 1.C.b. — Keep text that references the Notice of Regulatory Requirements (NORR).
Information related to the NORR needed to address DEQ Comprehensive Site Assessment (CSA)
Update comments shall be provided in the body of the CAPS in a comprehensive manner to
adequately evaluate site conditions and to refine remedial design to facilitate decision making
regarding corrective action.
• Section 1.D. — The proposed additional text is acceptable; however, the criteria that will be used
for evaluation and selection of remedial alternatives in the CAPS should be provided in Section 6.
• Section 1.E.b. — Duke Energy's clarification is acceptable, however, please acknowledge and
identify any other primary and secondary sources, non -coincident with the ash basins, that are on -
site and are currently or were formerly under the jurisdiction of DEQ.
• Sections 4.B. and 4.C. — A discussion of background concentrations in other similar settings is
acceptable; however, site -specific data will be the primary consideration for determination of
background threshold values (BTVs) for both soil and groundwater.
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� Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1636 Mail Service Center I Raleigh, North Carolina 27699-1636
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• Section 4.D. — Application of United States Environmental Protection Agency Nationally
Recommended Water Quality Criteria for Aquatic Life & Human Health by the DEQ is authorized
in the context of using narrative regulations for toxic controls where no surface water quality
standard has been adopted into state regulations. This is consistent with state authority under the
Clean Water Act, as well as state administrative code with respect to corrective action. DEQ will
work with Duke Energy to determine the appropriate response to exceedances of the 15A NCAC
02B surface water quality standards where applicable.
• Section 5 — Please include a 3-dimensional figure that illustrates groundwater impacts.
• Summary of Potential Receptors/Section 6 — The process of identifying potential receptors should
acknowledge that the hydraulics and groundwater/surface water flow patterns near the ash basins
have potentially changed over the years due to mounding and other site conditions; therefore, the
area that may have been impacted by may be more extensive than the area affected by current site
operations.
• Section 6 — Constituents of interest (COIs) that are subject to corrective action shall be constituents
with concentrations greater than the 15A NCAC .02L Groundwater Standards, Interim Maximum
Allowable Concentrations, or BTVs at or beyond the point of compliance, as well as, any
constituents within the compliance boundary that are predicted to cause a violation of any standard
in adjoining classified groundwaters, as directed by 15A NCAC .02L .0107(k). This concept shall
be reflected in any revised text.
• Section 6.A. — While the overall concept for data reduction to focus CAP development is
acceptable, sufficient data must be included to justify any proposed corrective action and an
agreement must be reached between Duke Energy and the DWR Regional Offices concerning
which COIs to address for corrective action. Also, providing data or responses to CSA Update
comments only in an appendix is not acceptable.
• Section 6.A.a.vi.3. — 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, public concern. The specific constituents that will be mapped in the CAPs shall be determined
by consensus between Duke Energy and the DEQ Regional Offices. If constituents display a
limited or discontinuous distribution that does not lend well to conventional mapping, then a
discussion of related site conditions should be provided in a manner that could understood by the
general public.
• Section 6.A.b. — The June 2019 cut-off date for inclusion of data into a CAP is acceptable for sites
where document submittals are scheduled for December 2019. However, CAPs due at later dates
should have different data cut-off dates based on Duke Energy's internal review process.
• Section 6.A.b.ii. —All 15A NCAC .02L Groundwater Standard exceedances should be
acknowledged and discussed. An agreement must be reached between Duke Energy and the
respective DWR Regional Offices concerning which COIs to address for corrective action.
• Section 6.A.c.i-ii — Removal of this section is acceptable. Under Section 6.D.a.i.ii, also list the
maximum concentrations of the COIs within and beyond the point of compliance for each media
(soil, groundwater, sediment, etc.).

• Section 6.B.a. — The process ofidentifying identifying potential receptors should acknowledge that the
hydraulics and groundwater/surface water flow patterns near the ash basins have potentially
changed over the years due to mounding and other site conditions, and therefore the area that may
have been impacted by past site operations may be more expanded than current site operations.
• Section 6.D.a.ii. — List the maximum concentrations of the COIs within and beyond the point of
compliance for each media (soil, groundwater, sediment, etc.).
• Section 6.D.a.iii. — Keep this Section and provide a succinct summary of modeling results,
including modeled concentrations above the 2L standards at or beyond the point of compliance for
the modeled time frame.
• Section 6.E.b and 6.E.b. iv. — Provide enough information and detail for the various remedial
alternatives considered to facilitate review. A higher level of cost detail shall be provided for the
remedial alternative selected in order to provide adequate information for decision making.
Otherwise, additional documentation may be required before an alternative is approved.
• Section 10 —Where applicable, isoconcentration maps shall provide mapping of analytical results
to background or non -detect levels to depict concentration gradients related to COI 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.
• Section 11. — Final content concerning appendices should be based on an agreement between Duke
Energy and the DEQ Regional Offices and should include all supporting documentation for
remedial alternative design.
Please include this correspondence as part of the CAP Update documents. If you have any questions, please
feel free to contact Steve Lanter (Central Office) at [phone].
Sincerely,
Ji �reggson, Deputy Director
Division of Water Resources
Attachments: (1) Duke Energy Interpretation of Corrective Action Plan Content Guidance Provided by
the North Carolina Department of Environmental Quality — January 23, 2019
(2) Supporting Rationale for Proposed Interpretation and Adjustments to the Corrective
Action Plan Content Guidance (NCDEQ April 2018) by Duke Energy January 2019
cc: WQROS Regional Office Supervisors
WQROS Central File Copy