NC0003425_Other Correspondence_20190314

DUKE
Paul Draovitch,P.E.
tiliZS V ILL Senior Vice President
ENERGY® Environmental,Health&Safety
526 S.Church Street
Mail Code:EC3XP
C) -
- -- Charlotte,NC 28202
[phone]
March 14, 2019
Ms. Sheila Holman '
Assistant Secretary
NC Department of Environmental Quality
217 West Jones Street
Raleigh NC 27603
RE: Startup of treatment components
Internal process flow modifications
Roxboro Steam Electric Plant
NC0003425
Person County
Dear Assistant Secretary Holman,
This letter is to provide details about the forthcoming startup of required treatment components
at the subject facility. Between the date of this letter and April 12, Duke Energy intends to
complete final commissioning of the newly constructed Lined Retention Basin ("LRB"), divert
certain waste streams from the ash basin to the LRB, and begin discharging from the LRB to
wastewater treatment system upstream of Outfall 003. It is our understanding, based on
language in the existing NPDES permit and on previous discussions with you and your staff,
that these changes can be implemented without a new or modified permit because they are
'internal to the system and do not materially affect the quality of the water discharged.
In accordance with the North Carolina Coal Ash Management Act's mandate to discontinue the
use of ash basins for wastewater treatment and a comparable requirement in the Federal CCR
Rule, Duke Energy has constructed replacement treatment systems for low volume waste and
other wastestreams that will continue to be generated in the future. These replacement
systems, commonly called "Lined Retention basins" or"LRB's" were constructed to replace ash
basins at sites that will remain active and generate electricity using coal as a fuel source.
Discharges from LRBs have been included in NPDES permits recently issued for other Duke
Energy generating stations where LRB replacement treatment for ash basins has been
constructed. The LRB replacement treatment system at the Roxboro station is nearing
completion of construction and will be ready for commissioning and use very soon.
As previously shared with your office, Duke must cease all flows into the existing ash basin at
the Roxboro plant by April 12 to comply with requirements in the Federal CCR rule. To comply
with this requirement, Duke must complete commissioning of the Roxboro LRB and divert
remaining waste streams from the ash basin to the LRB. Duke intends to undertake the
following activities at Roxboro to begin use of the new LRB and discontinue sending flows to the
ash basin under the existing permit.
1. Final commissioning of the LRB system components will be undertaken using service
water. Service water is water withdrawn from Hyco reservoir.

Ms. Sheila Holman
March 14, 2019
Page 2
2. After final construction checks using service water, Duke intends to redirect influent
flows from the ash basin to the LRB and place the LRB into service at Roxboro. For
clarity, this LRB system will only receive flows that previously were directed to the ash
basin and no new flows are included. Some flows have been removed (e.g. routine
bottom ash sluice waters) but no new sources of wastewater are present that were not
previously directed to the respective sites ash basins for treatment.
3. Flows from the LRB at Roxboro will be reintroduced into the wastewater flow path prior
to outfall 003 to the Hyco reservoir. The internal outfall has been constructed and
includes a diffuser system to assure rapid and complete mixing with other wastestreams
prior to discharge. As the flows at Roxboro, will not commingle solely with flows from the
existing ash basin before being commingled with cooling water flows, Duke will sample
the Roxboro LRB to demonstrate that discharges from the system meet Steam Electric
Effluent Guidelines for TSS and Oil and Grease. Duke will also sample the LRB
discharge for all constituents required to be sampled for the ash basin in our NPDES
permit. These internal sample results will be reported as an attachment to our monthly
required NPDES Discharge Monitoring report.
Duke Energy appreciates your agency's assistance as we have completed an unprecedented
amount of modifications at our coal fired facility's over the last few years. The compliance
deadlines associated with the North Carolina Coal Ash Management Act and Federal CCR rule
have been aggressive and required significant effort and expenditures comply with. Duke
Energy is focused on safely closing ash basins in ways that are dictated by science and
engineering and the work described in this submittal is being undertaken with that common goal
in mind.
Duke Energy hereby requests your concurrence with this action with the understanding
that this action is being undertaken under the conditions of the existing permit and is not
intended in any way to be binding on future permitting decisions or terms currently
under review by the Department.
If there are any questions about this matter, please contact Mr. Shannon Langley at (919) 546-
24 [e-mail].
\A
Sincerel ,
c., SZ -ice
11 IM.0 •
Paul Draovitch
Senior Vice Pre ident
Duke Energy

J
Ms. Sheila Holman
March 14, 2019
Page 3
Cc: RRO DEQ WQ Supervisor
3800 Barrett Drive
Raleigh, NC 27609
Jeff Poupart—DWQ Section Chief
1617 Mail Service center
Raleigh, NC 27699-1617
Shannon Langley—via email
Lori Tollie -via email
i