NC0024392_Fact Sheet_20230831

DEQ/DWR
FACT SHEET FOR NPDES PERMIT DEVELOPMENT
Duke Energy Carolinas LLC/ McGuire Nuclear Station
NCO024392
Facility Information
Facility Name:
McGuire Nuclear Station
Address:
12700 Hagers Ferry Rd. Huntersville, NC 28078
Permitted Flow (MGD):
Not Limited
County:
Mecklenburg
Facility Class:
II
Regional Office:
Mooresville
Pretreatment Program:
N/A
USGS Topo Quad:
B33NE
Permit Status:
Renewal
USGS Quad Name:
Lake Norman
Stream Characteristics
Receiving Stream:
Catawba River (002, 005)
Lake Norman (001, 004)
Stream Classification:
WS-IV
WS-IV B
Sub -basin:
03-08-33
HUC:
03050101
Drainage Area (mi2):
N/A
30Q2 (cfs):
N/A
Summer 7Q10 (cfs):
80 cfs (min release
Catawba River)
Winter 7Q10 (cfs):
80 cfs (min release
Catawba River)
Average Flow (cfs):
N/A
IWC %:
005 - 2.9 %
002- 0.8 %
Summary
Duke Energy Carolinas, LLC operates the McGuire Nuclear Station in Mecklenburg County at
the Cowans Ford Dam on Lake Norman. The station operates two nuclear steam generating
units. Intake water for cooling purposes is withdrawn from Lake Norman through a dual intake
system, a surface and a subsurface system. The Station operates five outfalls. These outfalls are
001, 002, 004, 005, and 006. Outfall 004 is an internal outfall discharging to outfall 001 before the
discharge to Lake Norman. Outfall 006 is an internal outfall discharging to outfall 002.
The permitted outfalls are summarized below:
• Outfall 001 (Once Through Cooling Water) - This outfall discharges once -through non -
contact cooling water from the nuclear service water system (RN), low pressure service
water, low level intake water, ventilation unit condensate, and storm drains. This outfall is
subject to 40 CFR 423.12 (6), once through cooling water. The facility received a 316(a)
variance for temperature for this outfall. There is no treatment at outfall 001.
Outfall 002 (Conventional Wastewater Treatment) - This outfall is a discharge of treated
wastewater from miscellaneous systems components cleaning, turbine building sumps,
water treatment room sumps, RO reject flow, condensate demineralizer backwashes, closed
cooling systems, the Standby Shutdown Facility sumps, laboratory drains, landfill leachate,
steam generator blowdown, wet lay-up, dewatering pumps, and other low volume
wastewater generating activities. Treatment system consists of a 200,000 gallon polyurethane
coated concrete initial holdup pond, two parallel 2.5 MG HDPE geomembrane lined settling
ponds, a 1 MG concrete based Geothane lined final holdup pond, chemical addition of
coagulants, oxidants, catalysts, pH control, and effluent pH adjustment by CO2 addition. This
discharge is subject to 40 CFR 423.12 (b)(3), low volume waste. This outfall discharges to the
Catawba River below the dam. The discharge occurs in batches two to three times per week.
Page 1 of 26

NC0024392
Internal Outfall 004 (Low Volume Wastes/Radwaste Liquid Waste Monitoring System) -
This outfall discharges water from the radwaste liquid monitoring system, floor and
equipment drains, laundry drains, ventilation unit drains, and other low volume wastewater
generating activities. This discharge is subject to 40 CFR 423.12 (b)(3) low volume waste. This
outfall combines with Outfall 001 before discharge to Lake Norman.
Outfall 005 (Wastewater Collection Basin)- This outfall discharges standby nuclear service
pond overflow, administrative building drains, main condenser cooling dewatering, HVAC
unit drains, storm drains, fire tank flushing, reverse osmosis reject flows. Treatment consists
of a 13.4 acre settling pond and surface skimmer. Discharge is to the Catawba River below
the dam. This discharge is subject to 40 CFR 423.12 (b)(3) low volume waste.
Outfall 006 (Chemical Metal Cleaning Waste) - This outfall is an internal outfall to the
waste treatment system (outfall 002) and discharges chemical metal cleaning wastes on an as -
needed basis. This discharge is subject to 40 CFR 423.12 (b)(5).
Receiving Stream
The Catawba River (Lake Norman) is listed in the 2014 North Carolina 303(d) list as impaired for
PCB Fish Tissue Advisory.
316 (a) Thermal variance
Outfall 001 includes alternative thermal limitations less stringent than the limits required by Clean
Water Act (CWA) section 306. The request for continuation of the variance is incorporated into
this permit renewal. To support the alternative limits and to comply with the terms and conditions
of the 316(a) variance Duke has implemented an annual monitoring plan for Lake Norman. The
Division has reviewed the annual reports and determined that the fish community currently found
in Lake Norman qualify as a balanced and indigenous community typical of a meso-oligotrophic
piedmont reservoir. The results of the studies support the implementation of less stringent thermal
limits.
Duke was granted the thermal variance for this facility on October 1985 and it has been renewed
with subsequent permits. Operations and load factors at the facility have remained unchanged.
316(b) Requirements
The McGuire Nuclear station is subject to the CWA 316(b) cooling water intake structure rules
effective October 2014. Below, please find Executive Summary of the 316(b) document
submitted by Duke.
Introduction
Duke Energy requests that determinations for impingement and entrainment best
technology available (BTA) be provided separately for the stations' two intake structures:
• Main Intake: withdraws raw water for cooling purposes through a shoreline -situated
intake structure.
• Low Level Intake (LLI): withdraws water through a secondary intake to provide
service water (continuously) and to support cooling system needs (on an infrequent
basis) for thermal efficiency.
Page 2 of 26

NCO024392
Main Intake
Based on the current design and operations of the Main Intake, Duke Energy requests the
following determinations based on the supporting information listed below.
1. A determination of de minimis rate of impingement, based on the following:
• A 2002 study documented low rates of impingement (2.2 to 2.3 fish/ day
excluding fragile species) and species diversity; additional information is
provided in Section 4.5.1.
• Operations at McGuire (detailed in Section 5) and the fish community
documented in Lake Norman (detailed in Section 4) have remained consistent
since the 2002 impingement study, thus the data are valid and representative of
current conditions.
• The cost -benefit analyses (Section 11) indicated that the potential benefits of
implementing an impingement -reduction technology for McGuire's Main
Intake does not justify the potential social costs, as each potential alternative
technology evaluated resulted in net negative benefits.
2. A determination of de minimis rate of entrainment, indicating that no additional
control requirements are warranted beyond existing facility operations, based on the
following:
• Results of a two-year entrainment characterization study performed at
McGuire's Main Intake (Section 9) demonstrated that entrainment at McGuire
consists primarily of post yolk -sac larvae of forage species (Clupeidae) and
White Perch; however, data from ongoing annual monitoring (Section 4)
demonstrates that Lake Norman continues to support a healthy forage fish base
supportive of predatory species such as temperate and warm water basses. As
such, reduction of clupeid losses due to entrainment and impingement is not
expected to provide a substantial benefit to the fishery, as evidenced by a low
equivalent yield impact of the various compliance scenarios (see Section 11).
• The cost -benefit analyses (Section 11) indicated that the potential benefits of
implementing an entrainment -reduction technology for McGuire's Main Intake
does not justify the potential social costs, as each potential technology evaluated
resulted in net negative benefits.
Low Level Intake
Based on the current design and operations of the LLI (secondary intake used for nuclear
service water and thermal compliance during peak demand of late summer), Duke Energy
requests the following determinations based on the supporting information listed below.
1 . A determination of de minimis rate of impingement, based on the following:
• Continuous operation of service water pumps results in through -screen
velocities (TSVs) of less than 0.5 feet per second (fps) at the LLI.
• TSVs at the LLI structure are greater than 0.5 fps only when the LLI pumps
operate, which is limited to one to five weeks during the warmest part of
the year when the potential for impingement is low (i.e., during peak
reservoir stratification).
• The design depth and restriction of operations to during peak summer
temperatures support the withdrawal of hypoxic water from the
hypolimnion of a thermally stratified Lake Norman, when fish are least
Page 3 of 26

NC0024392
likely to be present at the depth of the LLI, and thus reducing the
susceptibility of fish to impingement at the LLI.
• The operational precautions employed prior to pump initiation and
periodically during pump operation (periodic hydroacoustic monitoring of
LLI to determine fish presence and density near the intake).
2. A determination of de minimis rate of entrainment, indicating that no additional control
requirements are warranted beyond existing facility operations, based on the following:
• Continuous operation of service water pumps results in TSVs of less than 0.5
fps at the LLI.
TSVs at the LLI structure are greater than 0.5 fps only when the LLI pumps
operate, which is limited to one to five weeks during the warmest part of the
year when the potential for entrainment is low (i.e., during peak reservoir
stratification).
• The design depth and restriction of operations to during peak summer
temperatures support the withdrawal of hypoxic water from the hypolimnion
of a thermally stratified Lake Norman, when fish are least likely to be present
at the depth of the LLI, and thus reducing the susceptibility of fish to
impingement at the LLI.
Station Description
McGuire is a two -unit nuclear steam electric generating station in Huntersville, North Carolina,
and is owned and operated by Duke Energy. Commercial operation of Unit 1 began in 1981,
followed by Unit 2 in 1984. McGuire uses once -through (open -cycle) condenser cooling and
withdraws more than 125 million gallons per day (MGD) of raw water through a shoreline
situated cooling water intake structure (CWIS) referred to as the Main Intake. Raw water is also
withdrawn at a second intake (LLI) for nuclear service water (continuously) and to support
cooling system needs (on an infrequent basis) for thermal efficiency and/or for compliance with
a CWA §316(a) thermal effluent variance as identified in the National Pollutant Discharge
Elimination System (NPDES) permit. Nuclear service water is piped directly to the two nuclear
units via two17,500 gallons per minute (gpm) (25 MGD) pumps. Cooling water is pumped via
three 150,000 gpm (216 MGD) pumps and routed through a pipe to the Main Intake. The
discharge of the non -contact cooling water withdrawn via McGuire's Main Intake is currently
authorized under NPDES Permit No. NC0024392.
Regulatory Nexus
On August 15, 2014, the U.S. Environmental Protection Agency (USEPA) published in the
Federal Register the NPDES — Final Regulations to Establish Requirements for Cooling Water
Intake Structures at Existing Facilities and Amend Requirements at Phase I Facilities, referred to
as the Final Rule (Rule). The Rule establishes requirements under §316(b) of the CWA to ensure
that the location, design, construction, and capacity of a CWIS reflect the BTA for minimizing
impingement and entrainment at the CWIS. The Rule applies to existing facilities that withdraw
more than 2 MGD from Waters of the United States (WOTUS), use at least 25 percent of that
water exclusively for cooling purposes, and have an NPDES permit.
The Rule is applicable to McGuire due to the following:
Page 4 of 26

NC0024392
• McGuire withdraws raw water from Lake Norman, the source waterbody, through the
Main Intake for use in a once -through cooling water system and from the LLI for service
water and to support (on an infrequent basis) the station's cooling system.
• McGuire meets the minimum 2 MGD withdrawal rate criteria for actual intake flows (AIF)
and design intake flows (DIF). The total DIF at McGuire is 2,969 MGD (2,926 MGD at the
Main Intake and 43 MGD at the LLI). Based on data from January 2015 through December
2017, average annual AIF was 2,604 MGD at the Main Intake and 27 MGD at the LLI.
• McGuire uses greater than 25 percent of the water withdrawn from Lake Norman
exclusively for cooling water purposes (approximately 98.5 percent, or 2,926 MGD).
Because McGuire is subject to the Rule, Duke Energy has prepared technical information required
under CFR §122.21(r) (2) through (r) (13) for submittal to the North Carolina Department of
Environmental Quality (NCDEQ) Division of Water Resources NPDES permit Director (Director)
to facilitate the determination of BTA for the facility.
Under the Rule, the owner or operator of a facility must choose from one of seven compliance
options for impingement mortality (IM) reduction or an alternate exemption, as provided by the
Rule. The facility must also provide results from site -specific entrainment studies and information
identified at §122.21(r)(2) through (r)(13) and §125.98 to the permitting authority to aid in the
determination of whether site -specific controls would be required to reduce entrainment.
At §125.98, the Rule identifies specific information that the Director Must (§125.98 (f)(2))
consider and information that the Director May (§125.98 (f)(3)) consider in a site -specific
entrainment BTA determination. This Executive Summary describes the evaluation of these
compliance options and the Must and May factors for the Director to consider, as they relate to
McGuire.
Impingement Mortality Compliance
Per §122.21(r)(6), the owner of a facility must identify the chosen method of compliance with the
IM standard for the entire facility, or for each CWIS. Facilities may select one of seven IM BTA
compliance options (IM Options) provided in §125.94(c) paragraphs (1 ) through (7) unless
pursuing compliance under paragraphs (c)(11) de minimis rate of impingement or (c)(12) low
capacity utilization power generating units. The facility must also provide sufficient information
and justification to support the selected alternative compliance approach. Methods used to assess
the compliance options for addressing the requirements of §122.21 (r)(6) of the Rule are
summarized in Section 6 of this document.
Duke Energy performed a screening -level evaluation of IM reduction technologies and
alternative operational measures for the LLI and the Main Intake to identify feasible options that
could be implemented to reduce impingement at McGuire. Alternatives that were not considered
feasible were removed from further consideration. The remaining (i.e., short-listed) options were
evaluated in greater detail and the findings, which are presented in Section 6, identify the
technology or technologies that could result in the greatest benefit while minimizing
implementation, maintenance, and operational costs.
The compliance options were evaluated using the following step -wise process:
1 . Determine if McGuire is currently compliant with BTA for impingement under IM
Options 1, 2, or 3, based on existing design and operational data.
2. Evaluate existing impingement data to determine if impingement rates support a de
minimis rate of impingement determination by the Director.
Page 5 of 26

NC0024392
Calculate the most recent three-year average low capacity utilization rate (CUR) to
determine if it is below the 8 percent average capacity factor threshold established in
the Rule.
4. Assess the potential efficacy, technical feasibility, and relative costs of IM reduction
technologies and operational measures applicable to open -cycle cooling systems (IM
Options 4, 5, and 6).
5. Evaluate the potential efficacy, technical feasibility, and relative costs of ceasing
operations.
McGuire is an open -cycle system withdrawing more than 125 MGD of raw water and the
existing design and operation of the Main Intake results in TSV estimates of greater than 0.5 fps;
therefore, it does not comply with BTA Options 1, 2, or 3. Nuclear service water is withdrawn
continuously via the LLI structure resulting in TSVs less than 0.5 fps at the LLI. During limited
periods (i.e., one to five weeks per year), the additional LLI pumps are operated to supply raw
water from the bottom of Lake Norman to the Main Intake, resulting in TSVs greater than 0.5 fps
at the LLI. Additionally, based on existing conditions, McGuire does not currently comply with
IM BTA compliance Option 4 (typically applies to facilities in coastal environments) or Option 7
(not applicable as the most recent impingement study performed at McGuire did not include an
assessment of latent mortality). Further, McGuire does not meet the requirements for compliance
based on Low Capacity Utilization Rate (CUR) as a year-round, base load facility.
Therefore, Duke Energy performed a screening -level evaluation of IM reduction technologies
and alternative operational measures for the Main Intake and LLI to identify feasible options
that could be implemented to reduce impingement at McGuire and achieve compliance under
the remaining IM BTA options (provided in Section 6 and Appendix 6-A). The results of this
evaluation were used to identify the de minimis rate of impingement as the preferred compliance
option for McGuire's Main Intake and LLI, as described in the following sections.
Impingement Mortality Characterization
Although not required by the Rule, data from an impingement characterization study were
analyzed (see Section 4) to support the evaluation of IM Options. The study was performed at the
Main Intake from December 2000 to November 2002 (Duke Power 2003) and these results were
used to estimate annual IM losses representative of actual water withdrawals during 2016 and
2017.
Based on the Duke Power (2003) impingement study summarized in Section 4 and actual
volumes withdrawn at McGuire (from 2016 and 2017), annual IM was estimated at 2,175 fish in
2016 and 2,113 fish in 2017 for an estimated two-year average of 2,144 fish. Discounting the
fragile species (clupeids with impingement survival rates of less than 30 percent) from the
annual IM estimates resulted in revised annual estimates of 826 and 797 fish for 2016 and 2017,
respectively, or a loss of approximately 2.2 to 2.3 non -fragile fish per day.
The 10-year-old study employed methodologies that are consistent with contemporary methods
and quality assurance/quality control (QA/QC) protocols. Further, the withdrawal rates and
screen operations at McGuire have remained consistent over time (see Sections 3 and 5) and are
therefore representative of current conditions at the facility. Based on Duke Energy's annual
Maintenance Monitoring Program data, the biological community of Lake Norman has remained
consistent over the past twenty years, with expected, routine annual variation observed in the
Page 6 of 26

NC0024392
abundance of specific clupeid species (Duke Energy 2015). As such, these data indicate that the
impingement data collected during the 2000-2002 study performed at McGuire are
representative of existing conditions at the Main Intake the fish community in Lake Norman is
not adversely impacted by operations at McGuire.
Summary of Selected Impingement Mortality Compliance Options
Duke Energy performed a screening -level evaluation of IM reduction technologies and
alternative operational measures for the LLI and the Main Intake to identify feasible options that
could be implemented to reduce impingement at McGuire. The evaluation supports a
determination of de minimis rate of impingement for McGuire's LLI and Main Intake located on
Lake Norman.
Main Intake
Based on the evaluations and data presented in Section 4 and Section 11, annual
impingement at McGuire's Main Intake was estimated to be between 2,113 (based on 2016
operations) and 2,175 (based on operations in 2017) fish per year. Over half (approximately 62
percent) of the estimated total annual impingement losses presented for 2016 and 2017 were
comprised of fragile clupeid species (as defined at 40 CFR §125.92(m)), which exhibit
inherently low impingement survival (less than 30 percent survival as defined by the Rule)
and are not subject to the IM standard. Excluding these fragile species, total annual
impingement at McGuire is estimated at 826 and 797 fish per year, or approximately 2.3 and
2.2 fish per day in 2016 and 2017, respectively.
The estimated annual IM losses at McGuire are relatively low with respect to the natural life
history of the resident fish species in Lake Norman. In general, fish have reproductive
strategies which promote early maturity with high fecundity and no parental care (referred to
as r-selection reproductive strategy [MacArthur and Wilson 1967]). Therefore, fish spawn
many eggs but few survive through the developmental stages, from eggs to larvae to adults.
The high reproductive capacity (fecundity) compensates for the high natural mortality rates
experienced in early life stages. For example, the low end of estimated fecundity rates of
Bluegill (Lepomis macrochirus) or Largemouth Bass (Micropterus salmoides) is
approximately 10,000 eggs per female per spawning event. Assuming 99 percent of eggs do
not reach adulthood (EPRI 2004a), 25 reproducing adult fish would replace the number of
fish lost annually to impingement at McGuire.
Based on the species composition (high numbers of fragile species), minimal estimated
annual IM losses, low rate of impingement, and estimated equivalent adult, production
foregone, and equivalent yield losses to the fishery (see Section 11), a determination of de
minimis rate of impingement is requested as the IM BTA for McGuire's Main Intake, as
defined by the Rule. Further, Lake Norman is a managed fishery that continues to support a
balanced and productive fish community. These data demonstrate that the current design
and operations result in minimal IM and that the cost of implementing an impingement -
reduction technology for McGuire's Main Intake does not justify the potential social benefits.
Page 7 of 26

NC0024392
Low Level Intake
Results from the screening -level evaluation (Section 6) support the selection of the de
minimis rate of impingement compliance option for the McGuire LLI, as defined by the Rule,
based on the following factors:
1 . Continuous operation of service water pumps results in TSVs of less than 0.5 fps at
the LLI;
2. TSVs at the LLI structure are greater than 0.5 fps only when the additional LLI pumps
intermittently operate, which is limited to one to five weeks per year and only occurs
during the period of peak reservoir stratification when the potential for impingement
is low;
3. The design depth and restriction of operations to during peak summer temperatures
support the withdrawal of hypoxic water from the hypolimnion of a thermally
stratified Lake Norman, when fish are least likely to be present at the depth of the LLI,
and thus reducing the susceptibility of fish to impingement at the LLI; and
4. The operational precautions employed prior to pump initiation and periodically
during pump operation (periodic hydroacoustic monitoring of LLI to determine fish
presence and density near the intake).
These factors represent a framework for evaluating and adaptively managing LLI operations
to minimize the risk of operating when impingeable-sized fish are present near the LLI, and
minimizes the susceptibility of aquatic organisms in Lake Norman to impingement during
LLI operations.
Analyses Performed in Support of an Entrainment BTA Determination
This section summarizes the analyses required by the Rule for submission to the Director in
support of a site -specific best professional judgment (BPJ) review and entrainment BTA
determination. Although information presented under the requirements of §122.21(r)(2)
through (r)(8) of the Rule (i.e., Sections 1-8 of this document) provides useful perspective on
the location, design, and operation of the existing facility, this section focuses on those reports
prepared under §122.21 (r)(9) through (r)(13) of the rule (i.e., Sections 9-13), which offer
perspective on entrainment BTA. The process and results for evaluating the social costs,
social benefits, and other environmental impacts related to entrainment BTA, as prepared
under §122.21(r)(9) through (r)(12), are outlined along with a description of and results from
the peer review process in §122.21 (r)(13).
Entrainment Characterization Study — §122.21 (r)(9)
A two-year Entrainment Characterization Study (Study) was performed at McGuire in 2016
and 2017. The Study plan was reviewed by the North Carolina Department of Environmental
Quality (NCDEQ) and comments were incorporated into the Study plan report. Section 9 of
this document summarizes the two-year entrainment Study and the final report is provided
in Appendix 9-A.
Twice -monthly entrainment samples were collected at the entrance to the Main Intake
structure on Lake Norman, upstream of the bar racks and screens, using a pumped sampling
technique.
Sampling was performed from March 1 through October 31 in 2016 and 2017 (16 sampling
events in each year). Mean daily densities for days between each of the twice -monthly
Page 8 of 26

NC0024392
sampling events were determined through linear interpolation. The daily densities were then
used to calculate the mean rate of entrainment by month, which was multiplied by the total
monthly cooling water volume withdrawn at McGuire (see Section 5) to estimate total annual
entrainment losses at the McGuire Main Intake for 2016 and 2017 using actual water
withdrawal volumes. These data were also used to develop annual entrainment loss
estimates under hypothetical maximum water withdrawals at McGuire.
Comprehensive Technical Feasibility and Cost Evaluation Study—§122.21(r)(10)
The Rule requires an evaluation of feasibility and costs for alternative entrainment control
measures to support an entrainment BTA determination by the Director. Potential social costs
of alternative entrainment control measures must be estimated and compared to potential
social benefits. Due to the diversity in organism biology, habitat requirements, and different
body sizes of entrainable organisms, the available technologies and measures expected to be
reasonably effective at reducing entrainment are relatively limited. An evaluation of potential
entrainment reduction technologies for McGuire was performed to identify those that are
feasible and practicable to address requirements listed at §122.21(r)(10).
The process for developing this information for McGuire included.
• Evaluating potential siting locations to identify options posing minimal impact on
station operations and the surrounding community;
• Assessing potential for impact on nuclear safety;
• Assessing potential for overcoming operational problems (e.g., no
negative impacts to intake velocities or flows, does not exceed pressure
specifications of condensers);
• Evaluating potential for impacting operational reliability of McGuire;
• Evaluating facility -level Operation and Maintenance (O&M) costs associated with
each technology; and
• As required by the Rule, considering the feasibility and costs of three potential
technologies that could reduce rates of entrainment at McGuire, which include:
1. Retrofit to closed -cycle cooling;
2. Installation and operation of fine -mesh screens (FMS) with an aquatic
organism return system (includes fine -slot wedgewire screens and/or
dual -flow screens) at the Main Intake; and
3. Use of alternate water sources to replace all or some of the water used
in the once -through cooling system.
Assessment of Compliance Technology Feasibility
A cursory assessment of aquatic filter barriers, porous dikes, and variable speed pumps
indicated these technologies are infeasible and/or impractical at McGuire; thus, they were
excluded from further consideration. Alternate water supply sources were identified;
however none could provide the amount of water needed to replace the significant volume of
McGuire's intake flow, and thus were excluded from further consideration. However,
conversion to closed -cycle cooling (mechanical draft cooling towers [MDCT]) and installing
Page 9 of 26

NC0024392
FMS with an aquatic organism return system were considered technically feasible retrofit
technologies for McGuire; these two technologies were retained for further evaluation.
For the two potentially feasible technologies, a conceptual design, including location of
infrastructure, costs associated with engineering, scheduling, permitting, and constructing the
retrofit, and O&M costs through the remaining life of the station were developed. The net
present value (NPV) of the social costs of each technology was then developed based on the
estimated start of operations for each technology and estimated retirement date for the facility.
The complete process and results of the evaluations are provided in Section 10. A summary of
the results are presented below.
Costs of Compliance Technologies
Social Costs
Social costs were used to determine whether the potential entrainment reduction technology
costs would result in the plant becoming economically unfeasible to operate. Since a
premature shutdown of McGuire would result in social costs (i.e., lost jobs, income, and tax
base, and increased generation costs and emissions), installing entrainment reducing
technologies at McGuire to comply with the Rule represents additional operational costs that
would most likely be passed onto Duke Energy's electric customers in the form of higher
rates. Thus, the social costs were determined assuming that Duke Energy would incur these
additional costs and pass them on to electric customers.
The social costs of installing entrainment reduction technologies are estimated by
determining the design, construction, and installation costs of the evaluated technologies
along with the operation and maintenance (O&M), power system, externality, and permitting
costs. Following the requirements of the Rule, social costs were evaluated under two discount
rates: 3 and 7 percent (79 FR 158, 48428). Social costs include costs associated with compliance
with governmental regulations, power system effects, and externalities.
The estimated social costs (in 2018 dollars) of potential compliance technologies at McGuire
are presented in Table E-6. The analysis discounts the future stream of each of these social
costs at the relevant discount rate and sums them over the years they are specified to occur to
develop the total social cost estimate presented in the next to last column in Table E-6; annual
social costs for each technology are presented in the last column.
Also shown on Table E-6 are the compliance costs. Compliance costs are assumed to occur
over a 13-year period for the cooling tower retrofit scenario and over the remaining life of the
station (a 19year period) for FMS scenario, as discussed in Section 10.1.2. Power system costs
are due to construction -related outage impacts and efficiency and auxiliary load impacts
during operation.
Page 10 of 26

Table E-6. Total
Closed-
Cycie
Cooling
Retrofit
2.0-m m
Fine -Mesh
Ristroph
Traveling
Screens
Closed -
Cycle
Cooling
Retrofit
2.0-mm
Fine -Mesh
Ristroph
Traveling
Screens
and Social Costs of Feasible
$1.4913 $6.4M $1.858 $557 1 M $14.2M
$34.45M $2.42M $50.53M $0.63M $OM
$1.498 $6.4M $922.10M $277.1 M $8.1 M
$34.45M $2.42M $29.01 M $0.36M $OM
Note: $M = million dollars; $B = billion dollars
= million dollars; SB = billion dollars
NCO024392
at McGuire
SO-2M $11.4713 $113.2M
$4.2K $51.2M $2.69M
$0.1 M $733.6M $56.4M
$2.8K $29.4M $1.55M
Note:
1 The compliance costs are undiscounted and in 2018 dollars. The social costs associated with each
technology are discounted at 3 and 7 percent using the timing of technologies (see Section 10, Table 10-17).
2 Costs that contribute to increases in electricity prices.
3 Externality costs include decreases in social wellbeing resulting from property value, water consumption
(i.e., lost hydroelectric generation), and winter fishery (i.e., recreation) impacts.
Other Costs
Under certain compliance technology scenarios, the reduction or elimination of warm water
discharges at McGuire could occur, and could potentially lead to the loss of the thermal
refugia that supports the existing winter fishery and associated social costs (from reduced
angler catch rates) and benefits (potential localized improvements in water quality
parameters such as dissolved oxygen). However, DO does not typically decrease to levels
below the North Carolina water quality standards within the McGuire discharge zone;
therefore, the reduction in thermal discharges may not alter water quality substantially in
this area (Duke Energy 2017, 2018).
The fish species composition found in the vicinity of the discharge may also change in
response to reduced warm water discharges. Depending on the species, this may be seen as
either a cost or a benefit. Introduced species native to tropical regions may find refuge in the
discharge areas of power plants, which allows these species to persist in their non-native
range and the reduction or elimination of this refuge would be seen as a benefit. However, an
example of a species which may use the thermal discharge as refuge in Lake Norman is the
Threadfin Shad, which also provides an important forage base for recreational predator
species.
Annual fish community sampling throughout Lake Norman shows that abundance and size
structure of representative important species (defined as Largemouth Bass, Alabama Bass,
Bluegill, and Redbreast Sunfish) are not statistically different between thermally -influenced
Page 11 of 26

NCO024392
zones and non -influenced zones (Duke Energy 2017, 2018). Therefore, the effects (i.e., benefits)
of reducing thermal discharges with the installation of MDCTs at McGuire are not expected to
be substantial.
Benefits Valuation Study — §122.21(r)(11)
The goal of the Benefits Valuation Study was to demonstrate the estimated social benefits that
would be derived from impingement and entrainment reductions based on implementation
of one or more technologies at McGuire.
Estimates of Changes in Stock Size or Harvest Levels
Baseline (existing) impingement and entrainment losses (under actual and maximum water
withdrawals) and impingement and entrainment losses under selected compliance
technologies (MDCT and FMS) were estimated using 2016 and 2017 entrainment data
collected at McGuire (Section 9). The estimated reductions in entrainment were calculated for
the MDCT scenario assuming a percent reduction in water withdrawal volumes estimated
based on preliminary design assumptions, while the FMS scenario was estimated by
applying an exclusion calculation based on body size dimensions and a 2.0-mm mesh
opening.
The potential benefits to the fishery, due to changes in stock size or harvest levels, of the
estimated entrainment reductions were then estimated using commonly applied population
and harvest models (EPRI 2004a, 2012) that use numeric and mass based data in the
Production Foregone (PF) model, Equivalent Adult (EA) model, and Equivalent Yield (EY)
model. These three models were used to determine the potential entrainment reduction
benefits (for both "use" and "nonuse" scenarios) on commercial and recreational harvest, as
well as the effects of loss of forage associated with the entrainment of other finfish.
Parameters used in population modeling were derived from the literature (EPRI 2004a;
USEPA 2006) and also reflect site -specific information on the fishery of Lake Norman (when
available) and data specific to the recreational uses of the fishery. An evaluation of model
uncertainty was performed and is discussed in Appendix 11-E.
In evaluating the potential social benefits of entrainment reducing technologies determined
to be feasible for McGuire, a third option was evaluated: a complete or 100 percent reduction
in entrainment. This option assumes a shutdown and subsequent retirement of both units at
McGuire, as described in Section 11. To develop the NPV estimates, the benefits estimated for
each alternative were discounted at 3 and 7 percent annually and summed over the specified
time period used in the analysis.
Monetization of Benefits
The benefits of reductions in entrainment and impingement losses of early life stage fish are
best evaluated by translating losses to an ecological or human -use context, and assessing
differences in total losses among compliance technology scenarios discussed in Section 10.
The methodology for developing species and life -stage specific estimates of the potential
incremental reductions in entrainment or impingement among compliance technology
scenarios is detailed in Section 11 .
The estimation of social benefits was based on use benefits derived from potential changes in
recreational fishing stocks (e.g., equivalent adults, forage production foregone, and
equivalent yield) and their associated economic effects annualized over the remaining useful
Page 12 of 26

NC0024392
plant life (Section 10.1.2). Based on an evaluation of the potential for nonuse benefits of
entrainment reduction at McGuire, and given the precepts of nonuse values, the nonuse
benefits of reducing entrainment at McGuire are anticipated to be low. Specifically, given
estimated entrainment reduction costs and benefits, and the absence of federal or state listed
species in entrainment (Section 9), impingement (Section 4 and Section 6), and source
waterbody assessments (Section 4), correctly measured nonuse benefits would not impact a
BTA determination that considers benefits and costs based on historically applied criteria.
To develop the present value estimates, the benefits estimated for each feasible alternative are
discounted at 3 and 7 percent annually and summed over the specified time period used in
the analysis.
Other Benefits
Other benefits from reducing entrainment can include ecosystem effects such as population
resilience and support, nutrient cycling, natural species assemblages, and ecosystem health
and integrity (79 FR 158, 48371 ). The fisheries benefits study (summarized in Section 11) does
not evaluate other effects on the fish community, such as density -dependent influences
including increased competition, predation, or increased introduced species populations.
Increased survival of forage species would increase competition among the forage fishes, as
well as provide a greater forage base for predators. The dynamic effects among native and non-
native predators are not known (for instance, improved Largemouth Bass relative weight
[Duke Energy 2017], or greater increases in the Spotted Bass population).
The existing Main Intake does not include an aquatic organism return system and has no
means to return biomass to the source waterbody. A reduction in entrainment or
impingement, as well as the installation of an organism return system would allow carbon
(as live or dead fish) to be returned to Lake Norman. Live returned organisms would then
be made available as prey or to grow as adults, and dead organisms would be made available
as a resource for scavengers, detritivores, or decomposers.
Non -water Quality Environmental and Other Impacts Study—§122.21(r)(12)
The Rule at §122.21 (r)(12) calls for assessment of other non -water quality environmental
impacts, including estimates of the level of impact, for each technology or operational
measure considered under S12.21 It also calls for discussion of reasonable efforts to mitigate
the impacts; this information is presented in Section 12. The evaluation must address, if
relevant to the alternative technology being assessed, the following items:
• Estimates of changes to energy consumption, including but not limited to,
auxiliary power consumption and turbine backpressure energy penalty; .
Estimates of increases in air pollutant emissions;
• Estimates of changes in noise generation;
• A discussion of potential impacts to safety;
• A discussion of facility reliability;
• Estimation of changes in water consumption; and
• Discussion of efforts to mitigate these adverse impacts.
The conceptual approach to each technology (e.g., location and design of the cooling towers),
as defined in Section 10, has an important effect on the level of impacts discussed in Section
12. The quantitative engineering and costing analyses presented in Section 10 includes an
evaluation of potential impacts and incorporates reasonable estimates of impact mitigation
Page 13 of 26

NC0024392
and associated costs, thus concepts and approaches presented in Section 10 and 12 are
related.
Peer Review - $122.21(r)(13)
As required by the Rule at S122.21(r) (13), the reports prepared under $122.21 (r) (10) — (r) (12)
underwent external peer -reviewed by subject matter experts. Four expert peer reviewers
were selected in fields relevant to the material presented in the submittal package (i.e., power
plant engineering, aquatic biology, and resource economics). The qualifications of the peer
reviewers were submitted to NCDEQ on July 27, 2015. Consistent with the Rule's
requirements, Section 13 of this document provides a summary of the peer reviewer
qualifications (Appendix 13-A), documentation of formal peer review comments and
responses to those comments, and includes confirmation from reviewers of their satisfaction
with responses to comments and recommended revisions.
Additionally, informal peer review and guidance was requested during project
development regarding the overall approach to developing the Study Plans for entrainment
characterization as well as specifics on key technical issues related to entrainment -related
reports.
Entrainment BTA Factors that Must Be Considered
The Rule requires that the Director consider several factors in the written explanation of the
proposed entrainment BTA determination. The following Must factors to be considered for
entrainment BTA (§125.98(f)(2)) are:
• Numbers and types of organisms entrained, including federally listed, threatened
and endangered species, and designated critical habitat (e.g., prey base, glochidial
host species);
• Impact of changes in particulate emissions or other pollutants associated with
entrainment technologies;
• Land availability as it relates to the feasibility of entrainment technology; .
• Remaining useful plant life; and
• Quantitative and qualitative social benefits and costs of available entrainment
technologies.
While each of the Must factors are considered separately in Section 10 for the potential
technologies considered (i.e., MDCT and FMS with an aquatic organism return), a brief
summary of findings for each factor is presented below along with references to the relevant
section(s) of the report.
Numbers and Types of Organisms Entrained
Sections 9 and 11 present the number and type of organisms entrained based on the two-year
Study at McGuire, which were then annualized and adjusted for station flows (design and
actual intake flows) to estimate total annual entrainment at McGuire. The annual estimates
are presented separately for 2016 and 2017 based on the rates of entrainment documented
during the 2016-2017 Study. Total annual entrainment at McGuire, based on the actual water
withdrawn over the two-year period, was estimated at 476.8 million ichthyoplankton in 2016
and 374.7 million ichthyoplankton in 2017. Annual entrainment at McGuire included 12
distinct species from 8 families of fish, and consisted primarily of post yolk -sac larvae (48
percent) and young -of -year (51 percent) in 2016, and post yolk -sac larvae (98 percent) in 2017.
Page 14 of 26

NCO024392
The primary period of ichthyoplankton entrainment at the McGuire CWIS occurred during
late spring to early summer, from March through June (see Section 9). The period of
entrainment observed in the Study is consistent with observations made at other
southeastern U.S. reservoirs (EPRI 2011). It is also consistent with documented life history
information for the species entrained at McGuire (summarized in Appendix 4-A).
Annual entrainment loss estimates for the young -of -year life stage are primarily based on a
single event collection of a relatively large number of Inland Silverside (Menidia beryllina).
This collection is considered an anomaly and represents the first documented occurrence of
this species in Lake Norman; as such, a sensitivity analysis was performed to quantify model
response to inclusion of this species (see Appendix 11-A). Excluding this introduced species
from the data, the 2016 entrainment losses were dominated by post yolk -sac larvae (95
percent), similar to 2017.
These data indicate that post yolk -sac larvae of introduced White Perch (Morone americana) and
several species from the Clupeidae family are most susceptible to entrainment at the McGuire
CWIS (Main Intake). With the exclusion of anomalous Inland Silverside, clupeids represented
82 to 90 percent of entrainment and other than White Perch, few recreational species were
entrained. No endangered or threatened species were collected during either year of the Study,
and based on the absence of documented occurrences in Lake Norman, none are anticipated
to be susceptible to entrainment at the McGuire Main Intake.
It is important to place the rates of entrainment at McGuire into the context of the trends
documented for Lake Norman, the source waterbody (see Section 4):
• Duke Energy has monitored the Lake Norman fishery for over 30 consecutive years;
this monitoring has demonstrated a stable and balanced, self-sustaining population
with a healthy forage fish base supportive of predatory species such as temperate and
black basses (Duke Energy 2017).
• Some interannual variation has been documented in Lake Norman, which shows a
shifting species composition in response to introduction of non-native species;
however, these trends are not associated with or impacted by operations at McGuire
(Duke Energy 2017).
• The direct and indirect effects of the loss of organisms at McGuire, as demonstrated
through modeling (specifically designed to overestimate effects), resulted in a non -
observable impact to the recreational fishery (see Section 11).
These findings are interrelated and driven by the same factors: (1) species and life stages
entrained at McGuire exhibit high natural mortality, and (2) entrainment losses affect a very
small portion of the total resources available in Lake Norman. The majority of entrainable
organisms at McGuire were common fragile forage species resulting in a non -observable
impact on the recreational fishery and minimal nonuse value impacts.
Recreational species entrained at McGuire represented between 4.2 percent (2016) and 17.4
percent (2017) of total annual entrainment, with the majority of those consisting of post yolk -
sac larvae. The largest contribution to these values was from White Perch with an estimated
average 32.5 million post yolk -sac larvae entrained between 2016 and 2017. The relatively
small portion of White Perch eggs that were entrained (approximately 1.1 million) was likely
due to the demersal, adhesive nature of White Perch eggs (Rohde et al. 1994). To put these
entrainment numbers into context, a single White Perch female (depending on age) can
produce between 50,000 and 360,000 eggs per spawning event (Rohde et al. 1994). Because
this species reaches reproductive maturity early in life (as early as age 1), exhibits high
Page 15 of 26

NCO024392
fecundity (50,000 and 360,000 eggs per spawning event), and is a habitat generalist during
spawning, White Perch can rapidly become established in reservoirs and has been shown to
outcompete other natives in the fish community (Rohde et al. 1994). Further, White Perch
was introduced into Lake Norman, and has been implicated as one of several introduced
species likely responsible for declining populations of the native Largemouth Bass (Duke
Energy 2017). Based on this information and the high fecundity of this species, the
entrainment of White Perch at McGuire is not anticipated to have a negative impact on the
species diversity and abundance of Lake Norman.
Based on the estimated annual losses under existing conditions, the total annual foregone
fishery yield was estimated to be 16,682 pounds (lbs) in 2016 and 542 lbs in 2017. Foregone
fishery yield represents the total annual biomass lost from the recreational fishery due to
entrainment at McGuire. However, these values likely represent a conservative estimate (i.e.,
overestimate) of lost yield in response to multiple assumptions and BPJ decisions (i.e.,100
percent mortality of entrained organisms, all entrainment losses affect recreational taxa,
absence of density -dependent effects in the model that would occur in the biological
population, and BPJ decisions on surrogate species or values to utilize in the model)
employed during model development to maximize benefits of evaluated technologies (see
Section 11).
The incremental reductions in estimated entrainment losses and their impact to fishery
production and yield were modeled for each of the potential compliance scenarios described
in Section 11, and results are summarized in Table E-8 and Table E-9. The variability in FMS
efficacy between the two years was driven by differences in species composition and
abundance; with a large number of post yolk -sac larvae and juvenile Inland Silverside
collected in 2016 samples only. These small -bodied fish would be easily excluded on a 2.0-
mm FMS, thus increasing the exclusion efficiency.
As such, the number and type of organisms entrained (primarily non -protected, forage
species) do not provide a compelling basis under the Rule to evaluate additional entrainment
measures. The rates of entrainment at McGuire are not believed to negatively affect the Lake
Norman fishery.
Impacts of Changes in Air Emissions of Particulates and Other Pollutants
The assessment of entrainment technologies for BTA considers changes in pollutant air
emissions in Section 12. The increase in emissions is associated with two factors: (1 )
particulate matter (PM) emissions from the cooling tower associated with the concentration
of total dissolved solids (TDS) and total suspended solids (TSS) in the make-up water, and (2)
loss of generation capacity associated with parasitic loads and loss of efficiency based on the
entrainment technology operating requirements. Increased emissions are estimated to be far
more substantial for a potential retrofit to cooling towers than a retrofit to FMS.
Particulate emissions were estimated to travel 2,500 to 3,600 feet (ft) from the cooling towers
and not anticipated to result in damage to vegetation and/or infrastructure near McGuire.
Emissions associated with replacement of lost generation (approximately 18 percent of Duke
Energy's base load generation) would be dominated by carbon dioxide with substantially
lower amounts of sulfur dioxide, nitrogen oxides, and PM. These increased emissions are
assumed to occur at off -site fossil -fuel fired generators in the area. No attempt was made to
monetize the social costs of the increased emissions.
Page 16 of 26

NC0024392
Land Availability Related to Technology Retrofit Options
The availability of space for infrastructure associated with retrofitting for entrainment
technologies was considered in the assessment of entrainment BTA for McGuire. While
available land at McGuire is limited, space was identified for the placement of two sets of
cooling towers, one set for each of the two units, and the piping required to transmit cooling
water. Although this retrofit is potentially feasible, the constrained site results in higher
estimated installation costs, which affect the social cost estimates for the MDCT scenario. The
space constraints related to the FMS scenario were substantially reduced in comparison to the
closed -cycle cooling scenario.
Remaining Useful Plant Life
The remaining life of each generating unit impacts technology selection, O&M costs, potential
future technology repair costs (if the life of the unit is longer than the anticipated life of the
technology), and the benefits. Operating licenses for McGuire are due to expire in June 2041
for Unit 1 and in March 2043 for Unit 2 (USNRC 2002). A potential second license renewal
could extend the station's life by another 20 years, but for the purposes of this evaluation,
McGuire generating units were assumed to operate through June 2041 and March 2043. If the
original entrainment reduction technology is in good operating order at the respective
retirement date, it is assumed that the technology would be retired (no salvage value has been
evaluated). If the anticipated life of the technology is shorter than the anticipated life of the
units, this evaluation assumes that the technology would be repaired or rebuilt and remain in
service until the unit is retired.
Quantitative and Qualitative Social Benefits and Costs of Available Entrainment Technologies
Consistent with the Rule's requirements, and with review and input from external expert peer
reviewers, Duke Energy has developed rigorous estimates of both social costs and social
benefits of the two feasible entrainment BTA technologies for McGuire (i.e., MDCT and FMS
with aquatic organism return system). The methodologies and assumptions associated with
these estimates are discussed in detail in Section 10 and Section 11, and summarized in the
previous section.
Quantitative Cost to Benefit Comparison
The Director must consider the social costs (detailed in Section 10) and benefits (detailed in
Section 11) of each evaluated entrainment compliance option when determining the
maximum entrainment reduction warranted. In benefit -cost analysis, determinations of
compliance alternatives are made based on application of the concept of economic efficiency
under increasing costs and diminishing benefits. In this context, compliance alternatives are
economically efficient if they either have higher benefits and higher costs or lower benefits
and lower costs than other compliance alternatives; compliance alternatives with higher costs
and lower benefits are ruled out. When these economically efficient technologies are ordered
by increasing cost (or benefit), net benefits (benefits minus costs) increase, reach a maximum,
and then decrease.
The Rule, at §125.98(f)(4) indicates that where evaluated technologies result in social costs
that are in disproportion to and do not justify the social benefits, or result in unacceptable
adverse impacts that cannot be mitigated, the Director has the option of determining that no
additional control requirements are necessary beyond the existing technologies and
operational measures. Directly comparing social costs and social benefits is a sound approach
Page 17 of 26

NCO024392
to determining if a potentially feasible technology represents entrainment BTA on a BPJ basis.
In the event that the net benefits of a proposed entrainment technology or measure are
negative (i.e., social costs outweigh social benefits), there is no reasonable justification for the
selection of that technology/measure as BTA for entrainment.
A calculation of the total social cost, total impingement and entrainment benefits, and net
benefits associated with each feasible compliance alternative identified for McGuire shows
that the selected IM BTA option for McGuire has a net negative benefit of $457. The
incremental impact of entrainment compliance to the IM BTA requirement of the Rule is that
the net benefits become increasingly negative, estimated between-$50.7M for FMS to-$1.47B
for closed -cycle retrofit (MDCT), indicating that the disparity between social costs and social
benefits increases with increasing investment in entrainment reduction technologies,
especially in relation to the costs required for the IM compliance component of the Rule.
The comparison indicates that the social costs of entrainment reduction technologies at
McGuire clearly outweigh the social benefits, and the net benefits of both alternatives (MDCT
and FMS) are substantially negative. Further, the 100 percent reduction scenario (i.e.,
immediate retirement of McGuire), does not overcome the substantial social costs associated
with either the MDCT or FMS technologies; while the lost generation capacity would have a
significant impact on the operations and costs of electricity production for Duke Energy,
which would be passed onto electricity customers.
McGuire's chosen method to comply with the impingement compliance requirement (de
minimis rate of impingement) has zero net benefits: the social benefits and social costs are the
same. By comparison, 2.0-mm fine mesh screens have net benefits of-$50.7M and mechanical
draft cooling towers have net benefits of-$1.47B. Given that the net benefits beyond what is
required for impingement are negative, neither entrainment compliance option is warranted
as the BTA for meeting the site -specific entrainment requirement.
As such, in reviewing this application package for McGuire, NCDEQ has the discretion to
"reject otherwise available entrainment controls if the costs of the controls are not justified by
their associated benefits (taking into account monetized, quantified, and qualitative benefits),
and the other factors discussed in the Rule." Based on the evaluation of social costs and
benefits of each technology, McGuire's current configuration represents BTA for meeting the
site -specific entrainment requirements. The basis of this conclusion relies on the fact that each
of the potentially feasible compliance options evaluated for McGuire have negative net
benefits, meaning that the social costs of each of the entrainment compliance options are
greater than the social benefits:
• 2.0-mm fine -mesh screens have negative net benefits of-$50.7M and
• MDCTs have negative net benefits of-$1.47B.
Qualitative Cost to Benefit Comparison
The qualitative costs and benefits of reducing entrainment and IM are difficult to evaluate
and therefore are not quantified in the benefits valuation discussed in Section 11. These
qualitative effects, however, may result in ecosystem benefits such as increased population
resilience and support, and overall health and integrity of the ecosystem (79 FR 158, 48371).
The reduction in entrainment losses could also result in qualitative costs to the fish
community due to density -dependent influences such as increased competition, predation, or
increased population size of introduced species. However, based on species composition and
Page 18 of 26

NC0024392
entrainment losses documented at McGuire, qualitative benefits are not expected to be
significant or sufficient to outweigh the disproportionate social costs of entrainment and IM
reduction controls.
The elimination of warm water discharges at McGuire is a potential outcome under the
MDCTs scenario (see Section 11), which could lead to social costs or benefits. The warm
water discharges provide a thermal refuge for fish, thereby creating a winter fishery near
McGuire. Threadfin Shad, an important forage species, is one example of a species that
would potentially be impacted by the loss of thermal refuge provided by warm water
discharges at McGuire. Thus the loss of the warm water discharges can be viewed as a social
cost, especially to anglers that rely on the winter fishery each year.
The elimination of warm water in Lake Norman near McGuire's discharge zone could also
have a benefit in the form of improved water quality, which could result in increased
dissolved oxygen (DO) concentrations during peak summer temperatures when water
temperatures are already warm. However, since the DO levels in McGuire's discharge zone
do not typically decrease to levels below the North Carolina water quality standards, the
impact (i.e., benefit) to water quality would not be substantial.
• The direct and indirect effects of the loss of organisms at McGuire, as demonstrated through
modeling (specifically designed to overestimate effects), resulted in a modest measurable
impact to the recreational fishery.
• The social cost to social benefit comparison indicates that all modeled scenarios result in
zero or net -negative benefits.
Entrainment BTA Factors that Ma Be Considered
The May factors to be considered for entrainment BTA (§125.98(f)(3)) are:
• Entrainment impacts on the waterbody;
• Thermal discharge impacts;
• Credit for reductions in flow associated with the retirement of units occurring within
the ten years preceding October 14, 2014;
• Impacts on the reliability of energy delivery within the immediate area;
• Impacts on water consumption; and
• Availability of process water, grey water, waste water, reclaimed water, or other
waters of appropriate quantity and quality for reuse as cooling water.
The information from this list is included or addressed in detail in the study reports and
supporting documentation provided in Sections 2 through 12 of the compliance submittal
document. The findings of the entrainment BTA assessment relative to the factors that
NCDEQ may consider are provided below.
Entrainment Impacts on the Waterbody
Based on the information presented above and in Sections 1 through 12, entrainment at
McGuire does not result in substantial or adverse impacts to Lake Norman, with no observable
Page 19 of 26

NC0024392
or measurable impacts occurring based on the stability of the fishery and presence of a
balanced indigenous population (Sections 4 and 9). Duke Energy has over 30 years of biological
data to support this conclusion as detailed in Section 4. This was confirmed with quantitative
modeling of the effects of entrainment, using recent entrainment monitoring data collected at
McGuire in 2016 and 2017 (Section 9), including direct losses of recreational species as well as
indirect losses from trophic transfer of forage species to consumers or predators (see Section
11).
An assessment of cooling water residence time (CWRT), a volumetric rate, was performed for
McGuire. The CWRT, an alternative approach to defining the proportion of the source
waterbody that is withdrawn at the CWIS, is appropriate for a lacustrine waterbody and
presents a theoretical estimate of the time required for cooling water that exits the discharge
to be withdrawn by the intake in the recirculation process. Lake Norman, which was created
to provide cooling water for both McGuire and Marshall Steam Station, a facility owned by
Duke Energy to the north of McGuire, has a volume of approximately 356,374 million gallons.
The combined AIF for McGuire's Main Intake and LLI is 2,631 MGD based on the three most
recent years of data. Based on this withdrawal volume, Lake Norman's CWRT is
approximately 135 days. Additionally, estimates of the Main Intake and LLI area of influence
(AOI) were developed based on existing operations and targeted TSV thresholds of 0.5 fps
(impingement) and 0.1 and 0.3 fps (entrainment). At the most protective entrainment TSV
threshold (0.1 fps), the AOI extends 400 ft from the front of the Main Intake, an area
representing approximately 5.77 acres or approximately 0.02 percent of the total volume of
Lake Norman. Therefore, the AOI of the Main Intake is contained within the small intake
cove, between the floating debris boom and the intake structure.
The AOI at the LLI structure with just the nuclear service water pumps running is estimated
at 3 ft (0.5 fps velocity threshold) and 13 ft (0.1 fps velocity threshold). During the one to five
week period each summer when both the nuclear service water pumps and LLI pumps are
running, the AOI at the LLI structure is estimated at 43 ft (0.5 fps velocity threshold) and 212
ft (0.1 fps velocity threshold). However, as discussed in Section 6, the potential implications of
the impingement AOI for the LLI are reduced based on the location and depth of the
structure, timing, frequency, and duration of LLI operations, and adaptive management
strategies that minimize potential impacts resulting from LLI operations.
Thermal Discharge Impacts
The thermal discharge from McGuire is authorized under the facility's NPDES permit and a
§316(a) thermal variance based on a review that determined the variance is protective of the
balanced indigenous community in Lake Norman. Further, the thermal discharge from
McGuire provides thermal refuge for fish during cold winter months, and is currently
supporting a recreational winter fishery. As such, the reduction in thermal loading that
would occur with a potential cooling tower retrofit would not have a meaningful beneficial
effect on the nearby aquatic community, and instead, would eliminate a winter fishery that
provides social and economic value to the community. See Section 10 for additional details.
Credit for Flow Reductions
No unit retirements or associated reductions in flow occurred at McGuire within the
preceding 10year period.
Page 20 of 26

NC0024392
Impacts on the Reliability of Energy Delivery
McGuire is a large generating asset that supplies zero carbon electricity to Duke Energy's
customers. Maintaining safe and reliable energy delivery is imperative to Duke Energy, their
customers, and their shareholders, and has been considered in this entrainment BTA
assessment in the following manner:
During the conceptual design phase for potential entrainment technologies,
consideration was given to the location, configuration, operational requirements,
and other design specifics for each potential technology to improve generation
reliability. This information was incorporated into capital and social costs
estimated for each potential retrofit option.
Power system modeling (PROSYM) was performed by Duke Energy to evaluate
extent and system -wide impact of loss of generation capacity associated with
potential retrofit options to ensure reliable energy delivery and to estimate the
social costs of securing it.
Under the MDCT retrofit scenario, the station would need to operate at reduced power during
the warmest and most humid periods; the reduction is anticipated to result in reliability impacts
due to main condenser backpressure energy penalty. Additionally, during periods of peak
demand in winter, there would be potential for icing at McGuire's switchyard and/or on off -site
transmission lines. During normal winters, heat emanating from the cables may be sufficient to
prevent or minimize icing impacts. However, transmission corridors and switchyards may be at
increased risk during severe ice storm events potentially jeopardizing nuclear generation safety.
The MDCT could be designed for the maximum wet bulb temperature to mitigate the likelihood
of reduced power at McGuire, however, this option would result in a significantly larger
footprint and increased costs.
Under the FMS retrofit scenario, the primary source of reliability impacts would be due to screen
fouling or clogging, which would be mitigated by the assumed continuous rotation of the
screens and the use of pressure wash system. Therefore, the FMS retrofit scenario is not
anticipated to have substantial impacts to station reliability.
Impacts on Water Consumption
Section 12.2.6 considers changes in water consumption for candidate technologies evaluated in
Sections 10 through 12. Potential changes in water consumption with FMS would be negligible.
Monthly water consumption due to increased consumptive evaporation with the use of cooling
towers was quantified and compared to the monthly increased evaporation associated with
discharge of heated effluent from the once -through cooling system (forced evaporation). The
results of such an analysis are dependent on ambient weather conditions. Depending on the
month, cooling towers were estimated to increase water loss by 33 to 42 percent compared to
the once -through cooling system. Such losses would potentially require Duke Energy to release
water from upstream reservoirs to support Lake Norman pond elevations, or reduce zero
carbon hydropower generation at Cowans Ford Hydroelectric Station and six downstream
hydroelectric stations to mitigate the increased evaporative losses.
Availability of Alternate Water Sources for Reuse as Cooling Water
Based on a review of several potential sources of water in the area, no alternate source of
cooling water was found to be feasible. Factors considered in this assessment include the
potential quantity of water available and the distance of the source from McGuire.
Page 21 of 26

NC0024392
Groundwater and wastewater supplies within 5 miles of McGuire were determined to be
insufficient to support even a fraction of McGuire's cooling water requirements.
Conclusions
Based on the current design (location and depth) and operations of the Main Intake and low rate
and composition of impingement (2.2 to 2.3 non -fragile fish/day), a determination of de minimis
rate of impingement is requested as the IM Option for McGuire's Main Intake. Further, based on
the current design (location and depth), operations (frequency, timing, and duration), and
adaptive management (periodic hydroacoustic monitoring for fish presence and density) of the
LLI, Duke Energy requests a determination of de minimis rate of impingement as the compliance
approach for the LLI. The data presented in Section 6 and summarized in this Executive
Summary demonstrate that the current design and operations at McGuire result in minimal IM
and that the cost of implementing an impingement -reduction technology for McGuire's Main
Intake or LLI does not justify the potential social benefits.
As outlined in the Rule, the requirements of the NPDES Director include the following (40
CFR §125.98(f), Site -specific Entrainment Requirements):
(4) If all technologies considered have social costs not justified by the social benefits, or
have unacceptable adverse impacts that cannot be mitigated, the Director may
determine that no additional control requirements are necessary beyond what the
facility is already doing. The Director may reject an otherwise available technology as a
BTA standard for entrainment if the social costs are not justified by the social benefits.
Model -based estimates of the direct and indirect effects of the loss of organisms at McGuire,
based on conservative assumptions and BPJ decisions, indicated a non -observable impact to the
recreational fishery of Lake Norman. These data were then used to assess the social costs and
social benefits of potential entrainment reduction technologies, including: (1) a potential retrofit
to closed -cycle cooling (MDCT) and (2) the installation of FMS with an organism return system.
Monetized social costs and social benefits were estimated for both technologies to provide a
common basis for comparison, which is consistent with the goals and requirements of the Rule.
The estimates were based on conservative assumptions (e.g., all entrained organisms were
considered to affect recreational fisheries either directly as EAS or indirectly through trophic
transfer of PF) and include evaluations of uncertainty at multiple stages of the development
process. The social cost to social benefit comparison yielded substantial net -negative benefits for
the modeled entrainment reduction technologies, and unavoidable adverse effects were
identified for both technologies evaluated; however, a potential retrofit to closed -cycle cooling
(MDCT) would also result in increased air emissions, increased noise, loss of zero carbon
generation output, and potential impacts to system reliability.
Based on over 30 years of historical biological monitoring data, historical impingement
monitoring, and results of the entrainment Study presented in Section 9, Lake Norman supports
a diverse and balanced fishery in the presence of ongoing McGuire operations. No federal or
state threatened or endangered species are known to occur in Lake Norman, none were collected
in Duke Energy monitoring studies or the historical impingement study, and none were
collected during the 2016-2017 entrainment sampling activities. These data, combined with the
evaluations described in Sections 10 through 12, demonstrate that the two entrainment reduction
technologies (MDCT and FMS) are not justified as BTA for entrainment at McGuire as they
Page 22 of 26

NCO024392
would result in adverse effects and the social costs would be wholly disproportionate compared
to the potential social benefits.
The Director must consider the social costs and benefits of each evaluated entrainment
compliance option when determining the maximum entrainment reduction warranted. Based on
the evaluation of social costs and benefits of each technology, McGuire's current configuration
represents BTA for meeting the site -specific entrainment requirements
The Division agrees with the conclusion of the Duke report that "McGuire's current
configuration represents BTA for meeting the site -specific entrainment requirements" of the
Rule. The Division also agrees that station demonstrates de minimis rates of impingement at
both intakes, which does not warrant any additional impingement control measures.
These conclusions are supported by the four independent peer reviewers retained by Duke and
by the DWR environmental scientists.
It is also important to emphasize that the biological monitoring for more than 30 years at
McGuire concluded that Balanced and Indigenous Population is being maintained in Lake
Norman, which supports conclusions of the report.
Whole Effluent Toxicity
The facility has WET testing requirements on 3 outfalls: 001, 002 and 005.
Outfall 001 discharges to Lake Norman and has a current test requirement for acute toxicity
ceriodaphnia Pass/Fail Limit at 90%. All WET tests resulted in passing for this outfall. No
changes are recommended.
Outfall 002 discharges to the Catawba River and has an acute toxicity cerodaphnia LC 50 at 64%.
All WET tests resulted in passing.
Outfall 005 discharges to the Catawba River and has a chronic toxicity ceriodaphnia permit limit
at 1.4%. All WET tests resulted in passing for this outfall.
Reasonable Potential Analysis (RPA)
The Division conducted EPA -recommended analyses to determine the reasonable potential for
toxicants to be discharged at levels exceeding water quality standards/EPA criteria by this
facility. For the purposes of the RPA, the background concentrations for all parameters were
assumed to be below detection level. The RPA uses 95% probability level and 95% confidence
basis in accordance with the EPA Guidance entitled "Technical Support Document for Water
Quality -based Toxics Control." The RPA included evaluation of dissolved metals' standards,
utilizing a default hardness value of 25 mg/L CaCO3 for hardness -dependent metals.
Outfall 001
Calculations included: As, Be, Cd, Total Phenolic Compounds, Cr, Cu, CN, F, Pb, Hg, Mo, Ni, Se,
Ag, Zn, Al, B, Sulfate, and Tl (please see attached). The renewal application listed 2,926 MGD as
the highest reported flow during the last permit cycle. This flow was used in the RPA. The
analysis indicates no reasonable potential to violate the surface water quality standards or EPA
criteria.
Page 23 of 26

NC0024392
The Division also considered data for radioactive parameters of concern in the EPA Form 2C that
the facility submitted for the renewal, including Total Alpha radioactivity, Total Beta
radioactivity, Total Radium, and Radium 226. All these parameters were not detected in the
discharge.
Outfall 002
Calculations included: As, Be, Cd, Total Phenolic Compounds, Cr, Cu, CN, F, Pb, Hg, Mo, Ni, Se,
Ag, Zn, Al, B, Sulfate, and Tl (please see attached). The renewal application listed 0.73 MGD as
the highest reported flow during the last permit cycle. This flow was used in the RPA. The
analysis indicates no reasonable potential to violate the surface water quality standards or EPA
criteria.
The Division also considered data for radioactive parameters of concern in the EPA Form 2C that
the facility submitted for the renewal, including Total Alpha radioactivity, Total Beta
radioactivity, Total Radium, and Radium 226. All these parameters were not detected in the
discharge.
Outfall 005
Calculations included: As, Be, Cd, Total Phenolic Compounds, Cr, Cu, CN, F, Pb, Hg, Mo, Ni, Se,
Ag, Zn, Al, B, Sulfate, and Tl (please see attached). The renewal application listed 12.79 MGD as
the highest reported flow during the last permit cycle. This flow was used in the RPA The
analysis indicates no reasonable potential to violate the surface water quality standards or EPA
criteria.
The Division also considered data for radioactive parameters of concern in the EPA Form 2C that
the facility submitted for the renewal, including Total Alpha radioactivity, Total Beta
radioactivity, Total Radium, and Radium 226. All these parameters were not detected in the
discharge. The only exception was Total Beta radioactivity, which was well below state water
quality standard.
The proposed permit requires that EPA methods 200.7 or 200.8 (or the most current versions)
shall be used for analyses of all metals except for total mercury.
Compliance History
DMR data were reviewed for the period of April 2018 to April 2023. The facility violated permit
limits four times. All violations occurred in August of 2018. Two violations were for Oil and
Grease and two violations were for Total Suspended Solids.
Permit Limits Rationale
Outfall
Parameter
Limits/Condition*
Basis for Condition
Outfall 001
Flow
Monitor
14A NCAC 02B .0505
Free Available
Total Residual Chlorine
40 CFR 423.12 (b) (6)
Chlorine
was replaced with Free
Time of chlorine
Available Chlorine
addition
Temperature
95 °F (35' C) (Oct -
316(a) temperature variance
June)
Page 24 of 26

NC0024392
99 °F (37.2° C) (July -
Sept)
Outfall 002
Flow
Monitor
14A NCAC 02B .0505
TSS
30 mg/ L (MA)
40 CFR 423.12 (b) (3)
100 mg/ L (DM)
Oil & Grease
15 mg/L (MA)
40 CFR 423.12 (b) (3)
20 mg/ L (DM)
TRC
Monitor Monthly
14A NCAC 02B .0200
WTP discharge which is
chlorinated is included in this
outfall.
pH
6 to 9 S.U.
40 CFR 423.12 (b) (1)
Outfall 004
Flow
Monitor
14A NCAC 02B .0505
TSS
30 mg/ L (MA)
40 CFR 423.12 (b) (3)
100 mg/ L (DM)
Oil & Grease
15 mg/L (MA)
40 CFR 423.12 (b) (3)
20 mg/ L (DM)
Outfall 005
Flow
Monitor
14A NCAC 02B .0505
TSS
30 mg/ L (MA)
40 CFR 423.12 (b) (3)
100 mg/ L (DM)
15 mg/ L (MA)
40 CFR 423.12 (b) (3)
Oil & Grease
20 mg/L (DM)
pH
Monitor
40 CFR 423.12 (b) (1)
Outfall 006
Flow
Monitor
14A NCAC 02B .0505
TSS
30 mg/ L (MA)
40 CFR 423.12 (b) (3)
100 mg/ L (DM)
15 mg/ L (MA)
40 CFR 423.12 (b) (3)
Oil & Grease
20 mg/L (DM)
Total Recoverable
1 mg/ L MA
40 CFR 423.12 (b) (5)
Copper
1 mg/ L DM
Total Recoverable Iron
1 mg/ L MA
40 CFR 423.12 (b) (5)
1 mg/ L DM
*MA -monthly average, DM -daily maximum
Summary of proposed permit changes
1. The Division approved 316(b) report submitted by Duke and updated Section A. (21.)
accordingly.
2. The Section A. (16.) entitled Lake Monitoring Aquatic Environmental Maintenance
Monitoring Program has been removed to eliminate redundancy with 316a requirements.
Page 25 of 26

NCO024392
Proposed Schedule for Permit Issuance
Draft Permit to Public Notice:
Permit Scheduled to Issue:
State Contact Information
If you have any questions on any of the above information or on the attached permit, please contact
Sergei Chernikov at [phone].
Page 26 of 26