NC0001422_Water-Effect Ratio Study Quarterly Progress_20200925

fikt) DUKE L.V.Sutton Energy Complex
1` 801 Sutton Steam Plant Rd
ENERGY Wilmington, NC 28401
PROGRESS 910.341.4750
September 25, 2020
Certified Mail#7018 1130 0001 4419 9719(2 copies) RECEIVED
Mr. Sergei Chernikov
NCDEQ-DWR, Water Quality Permitting Section SEP 3 5 1010
1617 Mail Service Center
Raleigh, NC 27699-1617 NCDEQ/DWPJNPDES
Subject: Duke Energy Progress, LLC.
L. V. Sutton Energy Complex NPDES Permit NC0001422
Water-Effect Ratio (WER) Study Quarterly Progress
Dear Mr. Chernikov:
In accordance with Sections A. (2.) footnote 8. and A. (21.) 5. of the NPDES permit N0001422
effective 7/1/2020, Duke Energy Progress LLC hereby submits the WER Quarterly Progress Report.
If you have any questions concerning this submittal, please do not hesitate to contact either:
• Ms. Elizabeth Glenn, Environmental Specialist in our Permitting and Compliance Group,
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.
Sincerel�L�
Jame rriher
General Manager
C: Certified Mail#7018 1130 0001 4419 9726(1 copy)
Morella Sanchez-King
NC DEQ-DWQ, WiRO
127 Cardinal Drive Extension
Wilmington, NC 28405-3845

NPDES COPPER WATER-EFFECT RATIO (WER) STUDY
QUARTERLY PROGRESS REPORT
Duke Energy Progress, LLC - L.V. Sutton Energy Complex
NPDES Permit NC0001422
PURPOSE
The NPDES Permit NC0001422 (effective date 7/1/2020) for the L.V. Sutton Energy Complex
(Sutton) contains a Copper compliance schedule for Outfall 008 extension by 2 years to allow
the facility to conduct a Water-Effect Ratio (WER) study. This permit requires Duke Energy to
provide quarterly progress reports.
• Section A. (2.) Note 5. of the permit state: The (Total Copper) limits become effective on
October 1, 2022 to allow the facility to conduct a Water Effect Ratio Study. The facility
shall provide a quarterly progress reports to the Division.
• Section A. (21.) 5. of the permit state: The limits for Cu shall become effective on
October 1, 2022. The facility shall provide a quarterly progress reports to the Division.
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. mean sea level (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 sluice gates. Duke Energy staff
must manually open the sluice gate(s) at Outfall 001 to allow water to flow from the cooling pond
into the Cape Fear River. Under normal conditions the sluice gate(s) remain closed.
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.
Page 1 of 4

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
based on Reasonable Potential Analysis of discharges to the newly designated lake. Duke
Energy is seeking the development of site-specific copper monthly average and daily maximum
limits in accordance with 15A NCAC 02B, Water Quality Standards for Surface Waters.
DISCUSSION
The former three coal generating units 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.
Metals such as copper are generally less toxic to aquatic organisms in site water versus
laboratory dilution water, though all US Environmental Protection Agency (EPA) water quality
criteria (WQC) were derived from results of aquatic toxicity tests conducted in laboratory dilution
water. In response to the concern that the WQC are overly protective for most waters of the
United States, the USEPA approved several options for deriving site-specific limits. Included in
the list of options is the water-effect ratio (WER). The WER procedure produces a ratio that
represents the difference in toxicity between a specific wastewater facility's site water and
standard laboratory dilution water. This ratio, or WER, may be used by the permitting authority
to determine a site-specific metal permit limit for the facility. Guidance for conducting WER
studies was published by the EPA in 1994 as Interim Guidance on Determination and Use of
Water-Effect Ratios for Metals, (Interim Method).
Page 2 of 4

SUMMARY OF QUARTERLY ACTIONS
1 Q 2020
• Duke Energy submitted to DEQ a proposed study plan and sampling plan for the
development of a copper water effects ratio for NPDES Outfall 008.
• The Division approved the copper WER study and sampling plan.
2Q 2020
• Duke Energy began the study plan while closely monitoring COVID-19 and taking
precautions to protect the health and safety of our teammates.
3Q 2020
• NPDES Permit, effective date 7/1/2020. requires Duke Energy to provide quarterly
progress reports.
• The laboratory work for the WER study is completed.
• We are currently reviewing the data with our consultants.
Page 3 of 4

Duke Energy Progress. LLC. NPDES Permit NC00001422
l.V. Sutton Electric Plant 2020 Permit Application
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Figure 1: Figure 1- L.V. Sutton Cooling Pond
Page 4 of 4