NC0001422_More Information Received_20180627

ts 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
Certified Mail#7017 2680 0000 1260 8709(2 copies)
Mr. Jeffrey O. Poupart
NC RECEIVED/DENR/DWR
NCDEQ-DWR,
Water Quality Permitting Section
1617 Mail Service Center
Raleigh, NC 27699-1617 JUN 2 8 2018
Subject: Duke Energy Progress, LLC. Water Resources
L. V. Sutton Energy Complex NPDES Permit NC0001422 Permitting Section
Metals Evaluation Study Plan—9 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 first of several required reporting milestones. The referenced sections of the
NPDES permit state the following:
1. Nine months from the permit effective date, submit to DEQ an evaluation study plan describing
steps to be undertaken to identify the source of Cu and Ni at Outfall 001[and As, Se and Cu at
Outfall 008]in order to comply with the limits set forth in sections A.(1.) or A.(2.)of the permit.
The study should consider potential wastewater sources, practices such as vegetation
management, and background sources.
Additional evaluations will be provided as required by the permit, at the 18 month and 27 month
milestones.
If there are any questions, please contact either:
• Mr. Kent Tyndall, Environmental Professional and ORC-B for the L. V. Sutton Energy Complex;
phone [phone] or e-mail Kent.Tyndall @duke-energy.com; or
• Ms. LeToya Ogallo, Environmental Specialist at our North Carolina Regional Office, phone (919)
546-6647 or email [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,
cAkCLAQ9 —
Jason Talbott
Station Manager

NPDES METALS EVALUATION STUDY PLAN - 9 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 that Duke Energy
submit a study plan to identify actions that will be taken in order 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, while section A(30) of the permit requires a study plan
for copper and nickel at outfall 001.
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 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 of the 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
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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.
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. 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, uses stainless steel
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 amount of herbicides needed for control. Duke Energy also regularly
stocks triploid grass carp to prevent nuisance aquatic weed (macrophyte)growth within the cooling
pond.
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Historically, Duke Energy has used a copper-based herbicide to control a particular 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 is planned to be conducted in late 20181 or
spring 2019, depending on needs to apply the herbicide.
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 and 008 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, Duke Energy believes that measurable levels of arsenic and selenium in the wastewater
discharges from outfall 001 and 008 are due to legacy operations of the coal fired generating plant and
will decrease over time. Nickel has not been identified in samples collected since the issuance of the
October 2017 permit, however Duke Energy will continue to monitor for this parameter as required by
the permit and report on additional identification steps in future status reports.
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.
1 A herbicide treatment was planned for spring 2018, but the results of a vegetation survey indicated that
herbicide application was not needed at that time.
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Figure 1: Figure 1-L.V.Sutton Cooling Pond
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