NC0003425_Comments_20180423

DUKERoxboro Steam Station
i.J1` 1700 Dunnaway Road
ENERGY. Semora,NC 27343
April 23, 2018
REC ailENONRI®WR
Teresa Rodriquez, P E
NC Division of Water Resources (SPR ® 201
1617 Mail Service Center Water Resources
Raleigh, NC 27699-1617 permitting Section
Subject Comments on the DRAFT NPDES Permit for Roxboro Steam Electric Plant
Permit No.: NC0003425
Person County
Dear Ms Rodriquez
Duke Energy Progress, LLC (Duke Energy) appreciates the opportunity to meet with Division of Water
Resources NPDES permitting staff on February 27, 2018 to discuss issuance of the subject draft permit
The purpose of this letter is to provide additional information for items that were verbally requested by
the Division during that meeting and in subsequent discussions Duke Energy submits this letter as an
amendment to the pending permit application under consideration by the Division.
For clarity,the following items were discussed and confirmed
• The Division confirmed there will be no pH limits imposed on any new internal outfalls
• The Division confirmed that the frequency for toxicity sampling would be changed to quarterly
for outfall 003 and outfall 001 during routine operations and decanting with monthly monitoring
being imposed during"dewatering" of interstitial water activates.
• The Division will evaluate the appropriateness of the monthly average Selenium limit on outfall
006 This is based on the fact that one data point exists for Selenium during the last decade and
that the coal pile runoff flow, while in the NPDES wastewater permit, is a flow generated by
stormwater The stormwater benchmark for selenium in our permits issued by the Division is 56
ug/I. We also discussed how the mass of selenium associated with the coal pile runoff pond
discharge from outfall 006 is relatively small when compared to the ash basin and FGD scrubber
flows. This is relevant since the concern with Selenium is bioacculmuation, and mass is a more
important measure than concentration. Duke Energy has many years of fish tissue analysis
throughout Hyco Reservoir demonstrating that the fishery is not experiencing any impacts from
excessive bioacculuation of Selenium See attachment#2—NC DWR review of most recent
annual report for Hyco Reservoir. During meetings in 2017, Duke Energy requested that the

Selenium limit for outflall 006 be aligned with other stormwater requirements and be set at a
daily max of 56 ug/I. Duke Energy reiterates that requests with this submittal
• Division staff confirmed they will add language to the permit allowing a 5 day window on
temperature readings at the Afterbay USGS gauging station in the event of gauging station
damage Duke Energy suggests the same language as exists in the Belews Creek permit be used
for consistency.
• The Division agreed to evaluate the calculation of criteria for Thallium with the Standards and
Classifications Unit based on information Duke Energy provided during comment periods on
various permits and exisiting processes to assure the proposed limit is correct.
• The Division will add "extracted groundwater" as potential contributing flow to outfall 001 and
outfall 003. Characterization of groundwater was provided to the Division via email on
December 08,2016(attached). Duke Energy has discussed having"extracted groundwater" as a
contributing flow in each of the pending permits in previous discusions with Division staff given
the potential that we will undertake some long term groundwater extraction and remediation
around our ash basins. See attached letter from the Division (Attachment 1)that confirms that
extracted groundwater can be returned to ash basins and released at our Belews and Asheville
sites.
• Division staff confirmed the permit would not contain Attachments 1&2 and Condition A(15)
"Discharge from seepage"
• Division staff confimed that pH limits would be modified to "6.0"to"9.0" (the current DRAFT
permit lists pH limits as 6 to 9).
Based on subsequent discussions with regard to outfall 001, it is Duke Energy's understanding that the
Division will include this outfall in the reissued permit but also require removal of CCR material from the
remnant of the east ash basin located east of the onsite landfill Removal of material from this area will
likely require wet dredging and will require detailed engineering analysis to assure the stability of the
landfill is maintained. With activities proposed to remove the CCR materials in the east ash basin
remnant, Duke Energy requests a compliance schedule for limits imposed on Selenium,Arsenic, Flouride
&Sulfates for Outfall 001 during closure activities. If wet dredging is employed, Duke Energy will
provide filtration of filter press filtrate prior to release to outfall 001.
• Submittal of the closure plan to include removal of remaining CCR's from the east ash basin
remnant —03/31/19 (this will include a berm that will need to be designed to support the
landfill with the removal of this material)
• Apply for necessary permits and other agency approvals for work(including but not limited to
Solid waste and Dam Safety)—8/01/19
• Removal of CCR material to be completed by 12/31/21(if all permits are received by 12/31/19).
If permits are not received by 12/31/19,the completion date shall be 24 months after receipt of
all permits CCR material that can not be removed due to landfill stability concerns will be
quantified.
• Submit final report on amount of material removed and certifying completion of closure by
06/30/22

• Meet final limits or requests removal of outfall 001 by 06/30/2023.This would allow Duke
Energy to evaluate the discharge to determine whether additional treatment or modifications
are required to comply with effluent limits.
Duke Energy welcomes any further discussion to finalize the issuance of the pending NPDES Permit If
you have any questions, please contact Lori Tollie at 336.854.4916 or at Lori Tollie@duke-energy com
Sincerely,
Ac
Jason Haynes
Manager—Roxboro Steam Station
Duke Energy
Attachments
Cc Mr.Jon Hennessey—Roxboro Public Hearing officer
1617 Mail Service Center
Raleigh, NC 27699-1617