NC0001422_Other Correspondence_20190411

lcesills DUKE L.V.Sutton Energy Complex
801 Sutton Steam Plant Rd
ENERGY® Wilmington,NC 28401
PROGRESS o:910.341.4750
f:910.341.4790
June 27, 2018 RECEfvED/DENR/DWR
Certified Mail#7017 2680 0000 1260 9355(2 copies) APR 1 1 2019
Mr. Jeffrey O. Poupart
NCDEQ-DWR, Water Quality Permitting Section Water Resource`
1617 Mail Service Center Permitting Section
Raleigh, NC 27699-1617
Subject: Duke Energy Progress, LLC.
L. V. Sutton Energy Complex NPDES Permit NC0001422
Metals Evaluation Study Plan— 18 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 18-Month progress study.
An additional progress report will be provided at 27-months as required by the permit. If you have
any questions concerning this submittal, please do not hesitate to contact either:
• Mr. Steve Cahoon, Environmental Specialist at our North Carolina Regional Headquarters,
phone [phone] or email Steve.Cahoon©duke-energy.com, 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.
Sincerely,
41141 --- ,
J T nTalbott
Station Manager

NPDES METALS EVALUATION STUDY PLAN - 18 MONTH SUBMITTAL
DUKE ENERGY L.V. SUTTON ENERGY COMPLEX
NPDES PERMIT NC0001422
PURPOSE
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 Eighteen months from the permit effective date, submit a progress report describing the
findings of the study. If a source of Cu,As, and Se has been identified,the interim report
shall include proposed measures that will be evaluated to treat or eliminate the source
of pollutants. 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.
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 Eighteen months from the permit effective date, submit a progress report describing the
findings of the study. If a source of Cu and Ni has been identified, the interim report
shall include proposed measures that will be evaluated to treat or eliminate the source
of the pollutants. If a source of Cu and Ni is not 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.
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.
Page 1 of 5

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
(see Figure 1).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.The land surrounding the approximately 13.7-mile shoreline is generally
undeveloped and primarily forested.
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 Plant intake where it is
recirculated.There is no discharge of water from the cooling pond into the Cape Fear River except
through NPDES permitted Outfall 001. Duke Energy staff must manually open the discharge gate(s)at
Outfall 001 to allow water to flow from the cooling pond into the Cape Fear River.
Duke Energy maintains the level of the cooling pond by pumping from a raw water intake located on the
Cape Fear River into the cooling pond as needed.There are no streams or natural surface waters
contributing inflow to the cooling reservoir; all water within the pond consists of either rainfall,
wastewater discharges from the Sutton Plant,or pumped makeup water from the Cape Fear River.
Prior to 2015,the cooling pond was operated as a wastewater treatment unit under the terms of the
effective NPDES. In December 2015, NCDEQ issued a permit which classifies the cooling pond as waters
of the state, and therefore required Sutton Plant to meet water quality based limits on effluent
discharges into the pond through outfall 008.The 2015 permit contained metals monitoring
requirements at outfall 008 for selenium, arsenic, mercury, copper and zinc. In October 2017, a revised
permit was issued containing limits on arsenic, selenium, and copper.
Similarly,the 2015 permit contained metals discharge limits at outfall 001 for iron, cadmium, aluminum,
lead, arsenic,selenium,and mercury. Monitoring was required for copper and zinc. Due to newly
adopted, lower water quality standards in effect beginning 2017,the Division added limits for copper
and nickel at outfall 001.
Although the NPDES requires evaluation at two outfalls and for different parameters,the cooling pond is
a single recirculating system. Outfall 008 represents waters which have been recently discharged from
the operating power plant and Outfall 001 represents waters released from the cooling pond. 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.
DISCUSSION
Special conditions A.(29.)and A.(30.) of the permit require Duke Energy to outline efforts to evaluate
the sources of these metals at the outfall, including potential wastewater sources, practices such as
vegetation management, and background sources.
Page 2 of 5

Arsenic and Selenium
Arsenic and selenium are pollutants that would typically be expected as a result of the influence of coal
combustion residuals(CCR).The Sutton Plant has two onsite ash basins,which are adjacent to the
cooling pond. From 1972 until 2013,the basins discharged wastewater directly into the cooling pond
through NPDES permitted outfalls 002 and 004. Both outfalls can no longer discharge to Sutton Lake as
we continue closure of these ash basins.We are scheduled to remove all ash from these basins by
August 2019.As previously described,the wastewater within the cooling pond is recirculated and
discharged to the Cape Fear River through outfall 001. Due to this operational history, the ash basins are
the expected wastewater source of legacy arsenic and selenium to the cooling pond. Background levels
of arsenic and selenium, as monitored by both Duke Energy and the Lower Cape Fear River Basin
Association are typically below NC water quality standards.
Copper
The former coal generating unit which operated at the Sutton Plant from the 1950s until 2013 utilized
condenser tubes made in part from copper.These condenser tubes were in contact with the
recirculated cooling water and were the primary source of copper in the wastewater.The natural gas
combined cycle plant, brought online with the retirement of the coal units, use titanium condenser
tubes. However, it is likely that existing copper in the cooling pond is due to legacy coal operations.
Ambient copper levels monitored in the Cape Fear river are typically below water quality standards.
An additional potential source of copper in the cooling pond is the use of copper herbicides.There have
been occasional nuisance algal blooms in the pond, most notably in 1999, 2010 and 2012,which were
direct results of the increased phosphorus input from the Cape Fear River intake. Duke Energy
continually evaluates the pond for the presence of invasive species such as filamentous algae, and
routinely applies herbicide as early as possible after detection to prevent nuisance conditions within the
cooling pond while minimizing the quantity of herbicides needed for control. Duke Energy also regularly
stocks triploid grass carp to prevent nuisance aquatic weed (macrophyte)growth within the cooling
pond.
Historically, Duke Energy has used a copper-based herbicide to control a specific nuisance filamentous
alga (Lyngbia).This practice is allowed under the current NPDES permit. Duke Energy believes that if the
treatment is properly applied according to manufacturer's instructions, it should not increase copper
levels in the pond; however, this has never been thoroughly investigated.To evaluate whether the
application of the copper-based herbicide has the potential to effect water quality within the cooling
pond, Duke Energy intends to monitor and track water quality at set time intervals after herbicide
application to determine whether there is potential for either an immediate or delayed impact to
copper levels within the cooling pond.This sampling effort was planned to be conducted in late 20181
and again in spring 20192, depending on needs to apply the herbicide.
1 A herbicide treatment was planned for spring 2018, but the results of a vegetation survey indicated a herbicide
application was not needed.
2 A herbicide treatment was planned for spring 2019, but the results of a vegetation survey indicate a herbicide
application is not needed.
Page 3 of 5

Based on the results of the sampling, Duke Energy may choose to do additional monitoring,evaluate the
need for sediment samples, or begin to evaluate whether alternate treatment methodologies are
appropriate. Future status reports to the Division of Water Resources(DWR)will describe further steps
as they develop.
Nickel
According to the Reasonable Potential Analysis developed by DWR to support the 2017 NPDES permit
issuance,the nickel permit limit at outfall 001 was based on two data points reported above the water
quality standard. Since the permit issuance, Duke Energy has not detected nickel. Duke Energy will
continue to monitor nickel values at outfall 001 to determine if this pollutant is being discharged. If so,
Duke Energy will identify strategies to identify any source of nickel in future status reports to the
Division.
SUMMARY OF ACTIONS
In summary:
• Measurable levels of Arsenic in the wastewater discharges (circa 4-6 ug/L range)are due to
legacy operations of the coal fired generating plant and will decrease over time.
• Measurable levels of Selenium in the wastewater discharges (circa 2 ug/L range) are due to
legacy operations of the coal fired generating plant and will decrease over time.
• Measurable levels of Nickel in the wastewater discharges remain around 2 ug/L. Duke Energy
will continue to monitor for this parameter as required by the permit and report on additional
identification steps, if applicable, in future status reports.
• Measurable levels of Copper in the wastewater discharges remain around 6-7 ug/L.To identify
potential sources of copper in the cooling pond, Duke Energy will conduct ambient sampling in
conjunction with planned herbicide applications and report on next steps in future status
reports.
Page 4 of 5

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Figure 1: Figure 1- L.V. Sutton Cooling Pond
Page 5 of 5