NC0001422_Metals Evaluation Study Plan_20191218

4111N DUKE L.V.Sutton Energy Complex
ENERGY® 801 Sutton Steam
Wilmington, Rd
NCC 2840101
PROGRESS o:910.341.4750
f:910.341.4790
December 18, 2019
Certified Mail#7018 1130 0001 4419 9313(2 copies)
Mr. Jeffrey O. Poupart
NCDEQ-DWR, Water Quality Permitting Section RECEIVED
1617 Mail Service Center
Raleigh, NC 27699-1617 DEC 2 7 2019
Subject: Duke Energy Progress, LLC. NCDEQIDWRINPDES
L. V. Sutton Energy Complex NPDES Permit NC0001422
Metals Evaluation Study Plan—27 Month Compliance Milestone
Dear Mr. Poupart:
In accordance with Sections A. (29.) and A. (30.) of the NPDES permit N0001422, Duke Energy
Progress LLC hereby submits the 27-Month progress study.
If you have any questions concerning this submittal, please do not hesitate to contact either:
• Ms. Lori Tollie, Environmental Specialist at our North Carolina Regional Headquarters, phone
[phone] or email [e-mail], or
• Mr. Kent Tyndall, Environmental Professional for the L. V. Sutton Energy Complex Plant;
phone [phone] or e-mail [e-mail].
I certify, under penalty of law, that this document and all attachments were prepared under my direction or supervision
in accordance with a system designed to assure that qualified personnel properly gather and evaluate the information
submitted.Based on my inquiry of the person or persons who manage the system,or those persons directly responsible
for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and
complete. I am aware that there are significant penalties for submitting false information, including the possibility of
fines and imprisonment for knowing violations.
Sin 'rely,
Jason Talbott
Station Manager

.
Mr.Jeffery Poupart
NPDES Permit No.0001422
December 18, 2019
NPDES METALS EVALUATION STUDY PLAN - 27 MONTH SUBMITTAL
DUKE ENERGY L.V. SUTTON ENERGY COMPLEX
NPDES PERMIT NC0001422
The NPDES Permit NC0001422 for the L.V. Sutton Energy Complex (Sutton) requires Duke
Energy to submit a study plan to identify actions that will be taken to ensure the facility can
comply with metals limits contained within the permit.
• Section A.(29.) of the permit requires submittal of a study plan for copper, arsenic, and
selenium at outfall 008.
o Twenty-seven months from the permit effective date submit a progress report
describing the findings of the study. If a source of Cu, As, and Se was identified
in the 18-month report, this report should discuss the success of the efforts to treat
or eliminate sources of Cu, As, and Se. If a source of Cu, As, and Se has not been
identified, the interim report shall provide additional steps planned or necessary to
comply with the limits set forth in section A.(10.) of the permit.
• Section A.(30.) of the permit requires a study plan for copper and nickel at outfall 001.
o Twenty-seven months from the permit effective date submit a progress report. If a
source of Cu and Ni was identified in the 18-month report, this report should
discuss the success of the efforts to treat or eliminate sources of the pollutants. If a
source of Cu and Ni has not been identified, the interim report shall provide
additional steps planned or necessary to comply with the limits set forth in
sections A.(1.) or A.(2.) of the permit.
Background
In 1972, Carolina Power and Light constructed the 1,100-acre cooling pond at the L.V. Sutton
Energy Complex to provide condenser-cooling water for the three-unit 613-MW coal-fired
power plant. The cooling pond consists of a 2.36-mile central main dike, which bisects the pond,
and six wing dikes,ranging in length from 500 to 2,500 ft., designed to maximize circulation of
water and cooling efficiency. The cooling pond has a mean depth of 6.2 ft. with a normal pool
elevation of between 8.5 ft. and 10.5 ft. MSL.
Heated water from the steam condensation process is released to the effluent channel and flows
in a generally counterclockwise direction around the cooling pond to the Sutton Energy Complex
intake where it is recirculated.
Duke Energy maintains the level of the Sutton lake by pumping from a raw water intake located
on the Cape Fear River into the Sutton lake as needed. There are no streams or natural surface
waters contributing inflow to the Sutton lake; all water within the pond consists of either rainfall,
wastewater discharges from the Sutton Plant, groundwater recharge or pumped makeup water
from the Cape Fear River.

Mr.Jeffery Poupart
NPDES Permit No.0001422
December 18, 2019
Although the NPDES requires evaluation at two outfalls and for different parameters, the cooling
pond is a single recirculating system. Outfall 008 represents waters discharged from the
combined cycle natural gas plant to Sutton Lake and Outfall 001 represents wastewaters released
to the Cape Fear river. However, any evaluation of pollutant sources into the pond would pertain
to both outfalls. Therefore this report is organized as a single evaluation to meet both conditions,
A.(29.) and A.(30.), of the NPDES permit.
Results
Duke Energy investigated all waste streams from the combined cycle natural gas operation of the
L.V. Sutton Energy Complex, including the application of herbicides in or around the cooling
pond and could identify no current sources of Nickel, Arsenic, Selenium, and Copper.
Duke Energy has not detected Nickel since permit issuance in the discharge and believes Nickel
will not be a compliance issue.
The most likely source of arsenic and selenium seen in the discharge are a result of the influence
of coal combustion residuals (CCR) from the operation a three-unit coal-fired power plant from
1972 to 2013 and it is believed that the levels of both constituents will continue to decrease over
time.
Similarly, Duke Energy believes operation of the previous plant steam condenser admiralty brass
condenser tubes are the most likely source of historic and ongoing copper in the Sutton Lake
sediments and thereby the most likely source of Copper in the outfalls and in the Sutton Lake
water column. This flow from the previous plant ceased in 2013 but the copper appears to still
be within the sediments of the lake. The lake sediments contain copper from many years of
operating the retired coal-fired plant that had Admiralty Brass condenser tubes. A mass balance
study previously conducted by Duke Energy in the 1990s identified the condenser tubes as the
source of copper loading in the system. Condenser tube erosion/corrosion over many years of
time was the process by which copper found its way into the lake sediments. Without a
continued source of input into the system, we believe the concentrations observed in the outfalls
and lake water column is due to natural biogeochemical cycling of copper.
When operating at typical generation capacities,the Sutton Energy complex will withdraw the
entire volume of Sutton lake for process and steam cooling activities approximately every 6.5
days. Because of this operating condition and the shallow levels of the lake, the lake is very well
mixed and uniform. Said another way, the levels of copper measured in the outfall 008 location
are essentially the same as the intake levels and levels seen throughout the lake as a whole.
Because there is no ongoing identifiable source of copper, Duke Energy has evaluated several
mechanisms to assure compliance with the existing NPDES permit condition related to copper
concentrations. Routine measurements indicate that copper levels are generally just below to just
above the future limit. Duke evaluated the water hardness to evaluate if hardness dependent

•
Mr.Jeffery Poupart
NPDES Permit No.0001422
December 18, 2019
criteria could be developed. The water hardness values do not indicate any mechanisms to
recalculate the limit based on water hardness.
Duke Energy is undertaking a Water effects ratio (WER) study for copper. As such, Duke plans
to submit a modification requests for the NPDES permit in January 2020. This request will,
among other things, request an extension of the compliance date for copper at outfall 008 to
allow for the WER to be completed. Preliminary discussions regarding the WER have been had
with DWR NPDES permitting staff in recent weeks. A meeting is being planned for January
2020 to further discuss the operating conditions and study plan for a WER for copper at outfall
008.
Additionally, a modelling effort has been completed in accordance with the provision found in
permit condition A.(22.). Results of the modeling will be submitted and included in the requests
for modification of the permit in early 2020.