NC0038377_Report_20220202

( DUKE Mayo Steam Plant
ENERGY, Duke Energy Progress
10660 Boston Road
PROGRESS Roxboro, NC 27574
January 26, 2022 RECEIVED
North Carolina Department of Environmental Quality FEB QW
Division of Water Resources 2 2022''���'
1617 Mail Service Center VCDE
Raleigh NC 27699-1617 � ";'�i,
RE: Duke Energy Progress, LLC
Mayo Steam Electric Generating Plant,NPDES Permit NC0038377
Part A. (20.) Clean Water Act Section 316(b) Submittal
Dear Sir or Madam:
In accordance with the provisions of NPDES Permit NC0038377, Part A. (20.), following and
enclosed is our timely submittal of the requested Clean Water Act § 316(b) information for the
Mayo Steam Electric Generating Plant. Specifically, the Department has requested that the
submitted 316(b) information be provided by January 31, 2022. We believe that this submittal
completely satisfies this obligation.
As detailed in the enclosed reports, the Mayo Steam Electric Generating Plant meets Best
Technology Available for impingement and entrainment through the use of existing closed cycle
cooling using mechanical draft cooling towers.
Please contact Michael Smallwood ([e-mail], 704-382-4117) or
Lori Tollie ([e-mail], 336-854-4916) if there are any questions regarding
this submittal.
Sincerely,
Tom Copolo
General Manager, Mayo Steam Station
Attachment: 316(b) study reports for Mayo Steam Electric Generating Plant (pdf)
Cc: North Carolina Department of Environmental Quality (pdf and hardcopy)
Water Sciences Section
1623 Mail Service Center
Raleigh NC 27699-1623

Clean Water Act § 316(b)
Compliance Submittal
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MAYO STEAM ELECTRIC GENERATING PLANT
Roxboro, North Carolina
NPDES Permit NC0038377
Duke Energy Environmental Services I Environmental Programs
526 South Church Street
Charlotte NC 28202
January 2022
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ENERGY®

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Contents
Executive Summary 1
1 Introduction 4
2 Source Water Physical Data [§122.21(r)(2)] 7
2.1 Description of Source Waterbody[§122.21(r)(2)(i)] 7
2.2 Characterization of Source Waterbody[§122.21(r)(2)(ii)] 7
2.2.1 Geomorphology 8
2.2.2 Hydrology 8
2.2.3 Water Quality 8
2.3 Locational Maps[§ 122.21(r)(2)(ii) 11
3 Cooling Water Intake Structure Data [§ 122.21(r)(3)] 12
3.1 Description of MWIS Configuration [§122.21(r)(3)(i)] 12
3.2 Latitude and Longitude of MWIS[§122.21(r)(3)(ii)] 17
3.3 Description of MWIS Operation [§122.21(r)(3)(iii)] 17
3.4 Description of Intake Flows[§122.21(r)(3)(iv)] 18
3.5 Engineering Drawings of CWIS[§122.21(r)(3)(v)] 18
4 Source Water Baseline Biological Characterization Data [§122.21(r)(4)] 19
4.1 List of Unavailable Biological Data[§122.21(r)(4)(i)] 20
4.2 List of Species and Relative Abundance in the vicinity of CWIS[§122.21(r)(4)(ii)] 20
4.2.1 Exotic Species 25
4.3 Primary Growth Period 25
4.3.1 Reproduction and Larval Recruitment 25
4.4 Species and Life Stages Susceptible to Impingement and Entrainment 29
4.4.1 Impingement 29
4.4.2 Entrainment 30
4.4.3 Selected Species 32
4.5 Threatened, Endangered, and Other Protected Species Susceptible to Impingement and
Entrainment at the MWIS 34
4.6 Documentation of Consultation with Services 37
4.7 Incidental Take Exemption or Authorization from Services 37
4.8 Methods and Quality Assurance Procedures for Field Efforts 37
4.9 Fragile Species 37
5 Cooling Water System Data [§122.21(r)(5)(i)] 39
5.1 Description of Cooling Water System Operation [§122.21(r)(5)(i)] 39
5.1.1 Cooling Water System Operation 39
5.1.2 Proportion of Design Flow Used in the Cooling Water System 40
5.1.3 Cooling Water System Operation Characterization 41
5.1.4 Distribution of Water Reuse 42
5.1.5 Description of Reductions in Total Water Withdrawals 42
5.1.6 Description of Cooling Water Used in Manufacturing Process 42

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
5.1.7 Proportion of Source Waterbody Withdrawn 42
5.2 Design and Engineering Calculations[§122.21(r)(5)(ii)] 43
5.3 Description of Existing Impingement and Entrainment Reduction Measures[§122.21(r)(5)(iii)] 43
5.3.1 Best Technology Available for Entrainment 43
6 Chosen Method(s)of Compliance with Impingement Mortality Standard [§122.21(r)(6)] 45
7 Entrainment Performance Studies [§ 122.21(r)(7)] 47
7.1 Site-Specific Studies 47
7.2 Studies Conducted at Other Locations 47
8 Operational Status [§ 122.21(r)(8)] 48
8.1 Description of Operating Status[§122.21(r)(8)(i)] 48
8.1.1 Individual Unit Age 48
8.1.2 Utilization for Previous Five Years 48
8.1.3 Major Upgrades in Last Fifteen Years 49
8.2 Description of Consultation with Nuclear Regulatory Commission [§122.21(r)(8)(ii)] 49
8.3 Other Cooling Water Uses for Process Units[§122.21(r)(8)(iii)] 49
8.4 Description of Current and Future Production Schedules[§122.21(r)(8)(iv)] 49
8.5 Description of Plans or Schedules for New Units Planned within Five Years[§122.21(r)(8)(v)] 49
9 References 51
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Tables
Table 1-1. Facility and Flow Attributes and Permit Application Requirements 5
Table 1-2. Summary of§316(b) Rule for Existing Facilities Submittal Requirements for§122.21(r)(2)-(8). 6
Table 2-1. Annual Mean Concentration for Select Field and Analytical Parameters in the Vicinity of the Mayo
MWIS (Location B1). 10
Table 4-1.Total number and community composition (%) of fish collected by boat electrofishing in Mayo
Reservoir, 2015-2019. 22
Table 4-2. Total number(n), composition (%), and relative abundance (fish/hour-CPUE) of fish collected by
boat electrofishing in Mayo Reservoir, 2015-2019. (NC= No catch) 23
Table 4-3. Known Spawning and Recruitment Period of Fish Collected in Mayo Reservoir from 2015-2019 25
Table 4-4. Seasonal and Daily Activities of Species Collected in Mayo Reservoir from 2015-2019. 26
Table 4-5. Entrainment Potential for Fish (Egg and Larvae)Species Present near the Mayo MWIS 31
Table 4-6.Summary of Rare,Threatened, or Endangered (RTE)aquatic species listed for the area around Mayo
Reservoir, North Carolina, and record of occurrence of potential to occur near the Mayo MWIS. 35
Table 4-7. List of fragile species as defined by the EPA and their occurrence in Mayo Reservoir. 37
Table 5-1. Percent Monthly Proportion of Design Flow Withdrawn at the Mayo MWIS. 40
Table 5-2. Mayo MWIS Percent of Source Waterbody (Mayo Reservoir)Withdrawal 42
Table 5-3. MWIS TSV Calculations at Mayo Reservoir Pool Elevation. 43
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316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Figures
Figure 2-1. Map Showing the Mayo MWIS in the Lower Dan River Basin. 9
Figure 2-2. Duke Energy Progress Mayo Reservoir B1 and B2 monitoring locations in the vicinity of the Mayo
MWIS 10
Figure 3-1. Mayo Water Balance Diagram 14
Figure 3-2. Plan View of MWIS at Mayo 15
Figure 3-3. Section View of MWIS at Mayo 16
Figure 3-4. Traveling Screen Design of Mayo MWIS 17
Figure 4-1. Mayo Reservoir electrofishing survey transects 21
Figure 4-2.Aerial View of the MWIS within Mayo Reservoir. 30
Figure 5-1. Mayo Cooling Tower General Arrangement 40
Figure 5-2. Monthly Total MWIS Withdrawals at Mayo 41
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316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Appendices
Appendix A. Mayo Steam Electric Generating Plant§ 122.21(r)(2)-(8)Submittal Requirement Checklist.
Appendix B. Engineering Drawings of Makeup Water Intake Structure.
Appendix C. Engineering Calculations for Through-Screen Velocity.
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Abbreviations
°C degrees Celsius
°F degrees Fahrenheit
µS/cm micro Siemens per centimeter
AIF actual intake flow
A01 area of influence
BTA Best Technology Available
CCC closed cycle cooling
CFR Code of Federal Regulations
cfs cubic feet per second
cm centimeter
COC cycles of concentration
CWA Clean Water Act
CWIS Cooling Water Intake Structure
DIF design intake flow
Director NPDES Director
DO dissolved oxygen
Duke Energy Duke Energy Progress,LLC
EPA United States Environmental Protection Agency
ESA Endangered Species Act
fps feet per second
ft foot/feet
ft msl feet above mean sea level
gpm gallons per minute
HRSG heat recovery steam generator
HUC Hydrologic Unit Code
IPaC Information for Planning Conservation
IRP Integrated Resource Plan
m meter
micrometer
µS/cm microsiemens per centimeter
m3 cubic meters
Mayo Mayo Steam Electric Generating Plant
MDCT mechanical draft cooling tower
MGD million gallons per day
mg/L milligrams per liter
mm millimeters
MW megawatts
MWIS Makeup Water Intake Structure
NCDEQ North Carolina Department of Environmental Quality
NCUC North Carolina Utility Commission
NCNHP North Carolina Natural Heritage Program
NMFS National Marine Fisheries Service
NPDES National Pollutant Discharge Elimination System
NRDAR Natural Resource Damage Assessment and Restoration
NTU Nephelometric Turbidity Units
OTC once-through cooling
QA Quality Assurance
POA percent open area
Rule Clean Water Act§316(b)rule
RTE rare,threatened,or endangered
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316(b)Compliance Submittal
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TL total length
TSV through-screen velocity
USEPA United States Environmental Protection Agency
USFWS United States Fish and Wildlife Service
USGS United States Geological Survey
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316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Executive Summary
On August 15,2014,regulations implementing§316(b)of the final Clean Water Act(CWA)rule for existing
facilities (the Rule) were published in the Federal Register with an effective date of October 14, 2014.
Facilities subject to the Rule are required to develop and submit technical material, in accordance with
§122.21(r), that will be used by the National Pollutant Discharge Elimination System (NPDES) permit
Director(Director)to make a Best Technology Available(BTA)determination for the facility.
The Mayo Steam Electric Generating Plant (Mayo) began commercial operations in March 1983. Mayo is
comprised of two coal-fired boilers that provide steam to a single steam turbine with a current generating
capacity of 727 MW. Wastewater discharges from Mayo are authorized by NPDES Permit NC0038377.
Therefore, Mayo is an existing facility and subject to the Rule.
The §122.21(r) submittal material provided herein concludes that Mayo employs Best Technology
Available (BTA) for impingement and entrainment reduction with currently installed closed-cycle
cooling as described below and, as such, no further impingement or entrainment controls are
warranted.
Impingement BTA
The final Rule, at §125.94(c), requires existing facilities to employ one of seven impingement BTA
alternatives'. Mayo is compliant for impingement because it employs three of these alternatives,any one
of which would be wholly compliant for impingement:
• Primary impingement BTA—Closed-cycle cooling with a mechanical draft cooling tower is utilized
to provide makeup water which is consistent with a closed-cycle recirculating system (CCRS)
defined at§125.92(c)and meets the BTA Standards for Impingement Mortality at§125.94(c)(1).2
• Secondary impingement BTA — Cooling tower makeup water intake structure with a through-
screen velocity of less than 0.5 fps at normal source waterbody elevation;thus meeting the BTA
Standards for Impingement Mortality at§125.94(c)(2).
Overall, impingement at the facility is expected to be at near or zero due to the combination of low
makeup flows to the cooling tower and makeup intake structure low (<_0.5 fps)through-screen velocity.
There are no known federal or state listed species or designated critical habitats within the source
waterbody (Mayo Reservoir) in the vicinity of Mayo. As a result, potential adverse impacts due to
impingement are not expected to occur.
1 Or under specific circumstances one of nine alternatives,which includes§125.94(c)(11)and(12)in addition to
§125.94(c)(1)-(7).
2 Note that the source waterbody, Mayo Reservoir, meets the definition as a closed cooling recirculating system as
it was exclusively constructed to provide cooling water to the power generation facility. (§125.92(c)(2)).
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316(b)Compliance Submittal
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Entrainment BTA
The Rule does not prescribe BTA for entrainment; however,the Rule requires BTA to be determined on a
site-specific basis. This submittal demonstrates that Mayo meets BTA for entrainment based on the
following:
• Mayo uses closed-cycle cooling, which minimizes entrainment through flow reduction. During
the 2016-2020 period, Mayo's average withdrawal was 5.14 million gallons per day(MGD)which
is substantially less than the 125 MGD value of concern technically justified by the Rule. The flow
reduction achieved at Mayo,is calculated to be 98.1%as compared to an equivalent once-through
cooling (OTC) facility based on average makeup withdrawal flow, cooling tower design
characteristics, and 365 days per year operation. In addition, the average flow of 7.16 MGD is
reduced 73.5 percent from the design potential flow of 26.64 MGD.
• Statements made by the United States Environmental Protection Agency (EPA) in the preamble
to the Rule support this conclusion:
"Although this rule leaves the BTA entrainment determination to the Director,
with the possible BTA decisions ranging from no additional controls to closed-cycle
recirculating systems plus additional controls as warranted, EPA expects that the
Director, in the site-specific permitting proceeding, will determine that facilities
with properly operated closed-cycle recirculating systems do not require
additional entrainment reduction control measures. "3
This conclusion is further reiterated in the Response to Public Comments document, where EPA
states:
"EPA has made it clear that a facility that uses a closed-cycle recirculating
system, as defined in the rule, would meet the rule requirements for
impingement mortality at§125.94(c)(1). This rule language specifically identifies
closed-cycle as a compliance alternative for the [impingement mortality]
performance standards. EPA expects the Director would conclude that such a
facility would not be subject to additional entrainment controls to meet BTA."4
• The final Rule for new facilities published in the Federal Register on December 18, 2001 which
had an effective date of January 17, 2002, does prescribe BTA for entrainment', which Mayo
meets. Regulations are more stringent for new facilities than for existing facilities. By virtue of
meeting the most stringent entrainment BTA criteria (i.e., applicable to new facilities), Mayo is
compliant for entrainment BTA under the final Rule for existing facilities.
379 Fed.Reg. 48344(15 August 2014)
4 Response to Comments, Essay 14,p.62.
BTA for entrainment under the new facilities rule at 40 CFR §125.84(b) requires facilities with design intake flow
equal to or greater than 10 MGD,and under Track 1,to employ closed-cycle recirculating cooling as well.
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316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Potential impacts to fish and shellfish populations due to entrainment are also extremely unlikely due to:
• The use of closed cycle cooling via mechanical draft cooling towers;
• Low actual and design water withdrawals; and
• The calculated through screen velocity (TSV) at Mayo Reservoir normal pool elevation for the
design intake flow(DIF) case is 0.28 fps and under actual intake flow(AIF)conditions is 0.07 fps.
Based on the above facts, entrainment is reduced to the maximum extent warranted and additional
control measures are not warranted nor necessary for Mayo.
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316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
1 Introduction
Section 316(b)was enacted under the 1972 CWA,which also introduced the NPDES permit program.
Certain facilities with NPDES permits are subject to§316(b) requirements,which require the location,
design, construction, and capacity of the facility's cooling water intake structure (CWIS or MWIS as
referenced in this report)6 to reflect BTA for minimizing potential adverse environmental impacts.
On August 15, 2014, regulations implementing§316(b) of the CWA for existing facilities (Rule)were
published in the Federal Register with an effective date of October 14, 2014.The Rule applies to existing
facilities that withdraw more than 2 MGD from waters of the United States, use at least 25 percent of
that water exclusively for cooling purposes, and have or require an NPDES permit.
Facilities subject to the Rule are required to develop and submit technical material that will be used by
the NPDES Director(Director)to make a Best Technology Available (BTA) determination for the facility.
The actual intake flow (AIF)' and design intake flow(DIF)8 at a facility determines which submittals will
be required. As shown in Table 1-1,facilities with an AIF of 125 MGD or less have fewer application
submittal requirements and will generally be required to select from the impingement compliance
options contained in the final Rule. Facilities with an AIF in excess of 125 MGD are required to address
both impingement and entrainment, and provide specific entrainment studies,which may involve
extensive field studies and the analysis of alternative methods to reduce entrainment (§122.21(r)(9)-
(13)).
The§316(b) compliance schedule under the Rule is dependent on the facility's NPDES permit renewal
date. Facilities are to submit their§316(b) application material to the Director with their next permit
renewal application unless that permit renewal application is due prior to July 14, 2018, in which case an
alternate schedule may be requested.
6 CWIS(or MWIS as referenced in this report)is defined as the total physical structure and any associated
constructed waterways used to withdraw cooling water from Waters of the United States.The CWIS extends
from the point at which water is first withdrawn from waters of the United States up to,and including,the intake
pumps.
AIF is defined as the average volume of water withdrawn on an annual basis by the cooling intake structure over
the past 3 years initially and past 5 years after Oct. 14,2019.The calculation of AIF includes days of zero flow.AIF
does not include flows associated with emergency and fire suppression capacity.
DIF is defined as the value assigned during the CWIS design to the maximum instantaneous rate of flow of water
the CWIS is capable of withdrawing from a source waterbody.The facility's DIF may be adjusted to reflect
permanent changes to the maximum capabilities of the cooling water intake system to withdraw cooling water,
including pumps permanently removed from service,flow limit devices,and physical limitations of the piping. DIF
does not include values associated with emergency and fire suppression capacity or redundant pumps(i.e., back-
up pumps).
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316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Table 1-1. Facility and Flow Attributes and Permit Application Requirements.
Existing facility with DIF greater than 2
MGD and AIF greater than 125 MGD. §122.21(r)(2) (13)
Existing facility with DIF greater than 2
MGD and AIF less than 125 MGD. §122.21(r)(2) (8)
Existing facility with DIF of 2 MGD or
less, or less than 25 percent of AIF Director Best Professional Judgment
used for cooling purposes.
New units at existing facility. §122.21(r)(2), (3), (5), (8), and (14) and applicable
paragraphs (r)(4), (6), and (7)of§122.21(r)
Duke Energy Progress, LLC's (Duke Energy) Mayo is subject to the existing facility rule and, based on its
current configuration and operation (i.e., the facility has a DIF greater than 2 MGD and an AIF of less
than 125 MGD), Duke Energy is required to develop and submit each of the §122.21(r)(2)-(8) submittal
requirements (Table 1-2)with its next permit renewal application in accordance with the facility NPDES
operating permit and the Rule's technical and schedule requirements. Appendix A provides a checklist
summary of the specific requirements under each of the §122.21(r)(2)-(8) submittal requirements and
how each is addressed in this report or why it is not applicable to Mayo.
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316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Table 1-2.Summary of§316(b)Rule for Existing Facilities Submittal Requirements for§122.21(r)(2)-(8).
(2) Source Water Physical Data Characterization of the source waterbody including
intake area of influence.
(3) Cooling Water Intake Structure Data Characterization of the cooling water intake system;
includes drawings and narrative;description of
operation;water balance.
(4) Source Water Baseline Biological Characterization of the biological community in the
Characterization Data vicinity of the intake; life history summaries;
susceptibility to impingement and entrainment;
existing data; identification of missing data;
threatened and endangered species and designated
critical habitat summary for action area;
identification of fragile fish and shellfish species list
(<30 percent impingement survival).
(5) Cooling Water System Data Narrative description of cooling water system and
intake structure; proportion of design flow used;
water reuse summary; proportion of source
waterbody withdrawn (monthly);seasonal operation
summary; existing impingement mortality and
entrainment reduction measures;flow/megawatts
(MW) efficiency.
(6) Chosen Method of Compliance with Provides facility's proposed approach to meet the
Impingement Mortality Standard impingement mortality requirement (chosen from
seven available options); provides detailed study
plan for monitoring compliance, if required by
selected compliance option; addresses entrapment
where required.
(7) Entrainment Performance Studies Provides summary of relevant entrainment studies
(latent mortality,technology efficacy);can be from
the facility or elsewhere with justification;studies
should not be more than 10 years old without
justification; new studies are not required.
(8) Operational Status Provides operational status for each unit; age and
capacity utilization for the past 5 years; upgrades
within last 15 years; uprates and Nuclear Regulatory
Committee relicensing status for nuclear facilities;
decommissioning and replacement plans; current
and future operation as it relates to actual and
design intake flow.
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316(b)Compliance Submittal
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2 Source Water Physical Data [§122.21(r)(2)]
The information required to be submitted per 40 Code of Federal Regulations (CFR) §122.21(r)(2),
Source Water Physical Data, is as follows:
(i) A narrative description and scaled drawings showing the physical configuration of all source
water bodies used by your facility, including areal dimensions,depths, salinity and temperature regimes,
and other documentation that supports your determination of the waterbody type where each cooling
water intake structure is located;
(ii) Identification and characterization of the source waterbody's hydrological and
geomorphological features, as well as the methods you used to conduct any physical studies to
determine your intake's area of influence within the waterbody and the results of such studies;
(iii) Locational maps; and,
(iv) For new offshore oil and gas facilities that are not fixed facilities, a narrative description and/or
locational maps providing information on predicted locations within the waterbody during the permit
term in sufficient detail for the Director to determine the appropriateness of additional impingement
requirements under§125.134(b)(4).
Each of these requirements is described in the following subsections.
2.1 Description of Source Waterbody [§122.21(r)(2)(i)]
Mayo Reservoir is located in Person County, North Carolina (Fig 2-1). It is an impoundment of Mayo
Creek,which is a tributary of the Roanoke River Basin. The Mayo Makeup Water Intake Structure is
located on the western shore of the north end of Mayo Reservoir. This reservoir has a surface area of
1,133 hectares and has an average retention time of 36 months. Mayo Reservoir's watershed is
characterized by rolling hills with 55%forest, 18%agriculture,4% residential development, and less than
1%impervious cover(USGS 2012). The reservoir was constructed to provide make-up cooling water for
the Mayo Steam Electric Plant cooling towers and receives some plant process wastewaters via a
National Pollutant Discharge Elimination System (NPDES) permitted outfall (NC0038377,Outfall 002).
Mayo Reservoir is classified as Water Supply V(WS-V)waters by the North Carolina Department of
Environmental Quality(NCDEQ 2021).
Mayo Reservoir was constructed to "create a dependable supply of water to replace water loss from
evaporation and blow down from the plant's cooling towers" (USACE 1978). Authorization to construct
Mayo Reservoir was provided under the Section 404 of the Clean Water Act. Mayo Dam provides an
aerated minimum downstream flow that varies based on Mayo Reservoir elevation.
2.2 Characterization of Source Waterbody [§122.21(r)(2)(ii)]
To identify and characterize the primary source waterbody(i.e., Mayo Reservoir in the vicinity of the
MWIS)the following data were reviewed:
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316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
• Mayo Environmental Monitoring data 2015-2019(DEP 2016-2020)
The Duke Energy annual environmental monitoring program was created to meet requirements
specified in the NPDES Permit issued by the North Carolina Division of Water Resources (NCDWR). Since
1984, DEP has annually characterized and described the aquatic community within Mayo Reservoir.
Recent sample data (2015-2019)from the location near the MWIS(B1)will be used to characterize the
source water for the purpose of this report..
2.2.1 Geomorphology
Mayo Reservoir is located within the Piedmont Level III ecoregion, more specifically,the MWIS is located
within the Carolina Slate Belt (Level IV) of the Piedmont ecoregion. The Piedmont region is considered
to be the non-mountainous portion of the old Appalachians Highland. The northeast-southwest
trending Piedmont ecoregion comprises a transitional area between the mostly mountainous ecological
regions of the Appalachians to the northwest and the relatively flat coastal plain to the southeast. It is
an erosional terrain of moderately dissected irregular plains with some hills,with a complex mosaic of
Precambrian and Paleozoic metamorphic and igneous rocks. Most rocks of the Piedmont are covered by
a thick mantle of saprolite, except along some major stream valley bluffs and on a few scattered granitic
domes and flat rocks (Griffith et al. 2002).
The Carolina Slate Belt extends from Virginia, across the Carolinas, and into a small portion of eastern
Georgia. The Carolina Slate Belt band within North Carolina consist of mineral-rich metavolcanic and
metasedimentary rocks with slate cleavage,tending to be finer-grained and less metamorphosed than
other parts of the Piedmont and are somewhat less resistant to erosion. As a result,the Carolina Slate
Belt typically forms areas of slightly lower elevations with wider valleys. In North Carolina, however,
some parts of the region are more rugged and hilly, such as the Uwharrie Mountains, while other areas
have hills and linear ridges. Soils are often silty and clay silty,streams tend to dry up, and water yields
to wells are low as this region contains some of the lowest water-yielding rock units in North Carolina
(Griffith et al. 2002).
2.2.2 Hydrology
Portions of the Roanoke River Basin in North Carolina are divided into five 10-digit U.S. Geological
Survey hydrologic units, each designated by a Hydrologic Unit Code (HUC). The MWIS is located in the
Lawsons Creek-Dan River(0301010404) portion of the Lower Dan River HUC 03010104(Figure 2-1).
Land use within this section of the basin is predominantly forested followed by agriculture and
vegetated land in percent area (NCDEQ 2018).
2.2.3 Water Quality
As an element of the Mayo NPDES Permit, DEP collected a wide range of water quality data from
multiple sampling locations within Mayo Reservoir. Data from samples collected at location B1,which is
in the vicinity of the MWIS,from 2015-2019 (Figure 2-2)were used to characterize water quality. The
sampling program included either bi-monthly(2015 -2018)or quarterly(2019 only) collection of field
parameters and water chemistry samples from surface waters throughout Mayo Reservoir(DEP 2016-
2020). For the purposes of this report,a reduced list of water chemistry parameters is summarized in
Table 2-1. Additional water chemistry data can be found in the Mayo Annual Environmental Monitoring
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316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Reports (DEP 2016-2020).
Legend
Lower Dan River Basin(03010104) Q Stale Boundary
10 Digit Hydrological Units J County Boundaries prince Edward
0301010401.Hogans Creek-Dan River • May Steam Eectric Plant
0301010402.Country Line Creek
0301010403.Bach Creek-Dan River
0301010404,Lawson Creek-Dan River
0301010405.Hyco Lake N
0301010406 Hyco River 0 15
0301010407,Axons Creek-Dan River
O Miles Charlotte Lunenbl.
Virginia
PatsyNania
Halifax
( �-`''�,..�-.r"•---"` "` Mecklenburg
js
H� 'Danville
leprePr'i 2R5Reservoir
Mayo
✓"- Reservoir \
Mayo Steam
Caswell 31yco Lake 1 "' �-.—._. Electric Plant
"J--.�•. _ Person Granville Vance
North Carolina
Durham Franklin
Orange
Alamance
{ New Jerlity
PennsyNania
Ohio
rsey
West Virginia ar D
Kentucky Virginia
Chatham
Tennessee
North Carolina
Georg.ceouth Carolina Johnston
Figure 2-1. Map Showing the Mayo MWIS in the Lower Dan River Basin.
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316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
_ . 1,4 ., ',,,...:
..... .0 r
r *Location B2
Location B1
* Mayo MWIS S '.
}` I - .'t
t.
S s,
-'
Figure 2-2. Duke Energy Progress Mayo Reservoir B1 and B2 monitoring locations in the vicinity of the Mayo
MWIS.
Table 2-1.Annual Mean Concentration for Select Field and Analytical Parameters in the Vicinity of the Mayo
MWIS(Location B1).
Parameter 2015 2016 2017 2018 2019 _
Dissolved oxygen(mg/L)A 9.3 9.0 8.8 9.4 9.1
pH A 7.6 7.6 7.7 7.6 7.5
Water Temperature(°C)A 17.8 19.8 19.1 18.5 19.0
Specific Conductance(itS/cm)A 271 194 167 131 97
Turbidity(NTU)A 2.2 1.5 2.0 9.6 1.8
Total dissolved solids(mg/L)B 177 113 137 108 65
Ammonia-N (mg/L)B 0.065 0.015 0.020 0.032 0.024
Nitrate+ nitrite-N(mg/L)B 0.020 0.018 0.024 0.034 0.053
Total nitrogen(mg/L)B 0.30 0.17 0.19 0.30 0.31
Total phosphorus (mg/L)B 0.016 0.011 0.024 0.019 0.006
Total organic carbon (mg/L)B 4.2 3.9 4.2 4.4 4.6
Calcium(mg/L)B 24.1 16.8 15.5 12.1 7.8 _
Chloride(mg/L)B 49.4 31.6 24.4 18.1 8.9
Magnesium (mg/L)B 9.2 6.7 6.1 4.7 2.9
Sodium (mg/L)B 7.0 6.2 6.2 5.0 3.0
Arsenic (µg/L)B 1.0 0.8 1.1 1.3 0.6
Selenium (µg/L)B 0.3 0.4 0.4 0.3 0.3
Sulfate (mg/L)B 27.4 22.2 21.6 20.9 9.0
10
i

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Parameter 2015 2016 2017 2018 2019
Total alkalinity(mg/Las CaCO3)B 18.3 18.9 20.6 21.3 21.6
Hardness(mg equiv.CaCO3/L)B 98.2 70.0 64.0 49.7 31.6
"Field parameter.
'Analytical parameter.
Mayo Reservoir is typically characterized by low to moderate biological productivity. The most recent
assessment conducted by the North Carolina Division of Water Resources determined a trophic state
index classification of oligotrophic for the reservoir(NCDWR 2014). The relatively small watershed area,
low water inflow,and limited shoreline development within the watershed influences the amount of
nutrients entering the reservoir and the subsequent biological productivity. Productivity, as measured
by chlorophyll a concentration was relatively low and reflected the nutrient-limited conditions present
in the reservoir(DEP 2020). Annual mean concentrations of chlorophyll a near the MWIS(Location B2)
were 1.6, 1.3, 1.3, 3.5 and 4.5 (µg/L)from 2015-2019 respectively.
Mean annual concentrations of select water quality parameters within Mayo Reservoir near the MWIS
appeared to be consistent or trending down from 2015-2019. Annual mean concentrations of total
dissolved solids, chloride, hardness, and specific conductance have all exhibited declines since operation
of the thermal evaporator system for flue gas desulfurization (FGD)wastewater began during early 2015
(DEP 2020). Concentrations for these constituents as well as arsenic and selenium have reached pre-
FGD levels.
2.3 Locational Maps [§ 122.21(r)(2)(ii)
An aerial photograph of the Mayo MWIS and the associated environmental monitoring locations is
provided in Figure 2-2 (Section 2.2.3) and Figure 4-2 (Section 4.4.2).
11

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
3 Cooling Water Intake Structure Data [§
122.21(r)(3)]
The information required to be submitted per 40 CFR§122.21(r)(3), Cooling Water Intake Structure
Data, is outlined as follows:
(i) A narrative description of the configuration of each of the cooling water intake
structures and where it is located in the waterbody and in the water column;
(ii) Latitude and longitude in degrees, minutes, and seconds for each of the cooling water
intake structures;
(iii) A narrative description of the operation of each of the cooling water intake structures,
including design intake flows, daily hours of operation, number of days of the year in operation
and seasonal changes, if applicable;
(iv) A flow distribution and water balance diagram that includes all sources of water to the
facility, recirculating flows, and discharges; and
(v) Engineering drawings of the cooling water intake structure.
Each of these requirements is described in the following subsections.
3.1 Description of MWIS Configuration [§122.21(r)(3)(i)]
Cooling tower makeup water for Mayo is withdrawn from the Mayo Reservoir via the existing MWIS.
The MWIS is integrated with the reservoir shoreline.
Pumped raw water is utilized for other non-cooling purposes such as the flue gas desulfurization (FGD)
system, and other plant needs. Approximately 72 percent of the withdrawn water is used for cooling
tower makeup(see Figure 3-1 for the water balance diagram).
The raw water intake system at Mayo consists of two conventional traveling screens, one fixed screen,
two cooling tower makeup pumps,two FGD makeup pumps,fire protection system pumps, and piping
necessary to convey the pumped water. The makeup water intake structure is divided as follows:
• Bay 1—consists of one conventional traveling screen and one cooling tower makeup pump with
a rated capacity of 18,500 gpm. The traveling screen rotates as required to remove
accumulated debris and has 3/8" mesh openings. The bay well is 8'wide, 56' high, and
• Bay 2—identical to Bay 1.
• Bay 3—consists of one fixed screen (non-operable traveling screen),two FGD makeup pumps,
and fire protection pumps. Note that during extreme drought conditions, a temporary pump
(approximately 16,800 gpm)can also be installed in this bay to provide cooling tower makeup
water.
12

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Cooling tower makeup water is withdrawn from Mayo Reservoir by two pumps located in separate
pump bays. The invert of the pump structure is at 390.0 feet and normal Mayo Reservoir pool level is
434.0 feet. As viewed from the reservoir to the plant, each cooling tower makeup bay consists of a trash
rack,traveling screen, and a pump. Each pump bay is 8'wide and the traveling screens are 6'-10" in
width. A trash rack consisting of 3/8"thick steel bars with 3" center spacing is located at the entrance to
each bay for screening of large debris. The traveling screens have composite frames and stainless steel
mesh with 3/8"square openings. Figure 3-4 provides the traveling screen details. Critical Mayo
Reservoir elevations relative to the makeup intake structure are provided below:
Parameter Elevation,feet
MWIS Top of Structure 446.0
"High" (100 year flood) 437.5
"Normal" (Pool) 434.0
"Low" 407.0
"Low-Low" 398.0
MWIS Invert 390.0
Each traveling screen is 126 feet in length and consists of 63 identical panels that are 6'-10"wide and 2'
high. The traveling screen forms a continuous loop with a total height of 57'as measured from the
center of the head shaft sprocket to the center of the boot radius. The traveling screen mesh openings
are square and 3/8"wide. Traveling screens are periodically rotated as dictated by plant operations. A
spray system removes debris as the traveling screens are rotated with the resultant water and debris
returned to the Mayo Reservoir.
The cooling tower makeup pumps are vertical single stage pumps with a guaranteed flow of 16,800 gpm
each (24.2 MGD). As measured from the impeller bell to the top of the makeup structure operating
deck, each pump shaft is 54'4" in length. Typically, one makeup pump operates with the other makeup
pump functioning as a backup. Therefore,the maximum pump capacity(or DIF) of the cooling tower
makeup pumps is 24.2 MGD. Each of the makeup water intake pumps discharge to a common pipe that
terminates at the cooling tower basin.
Figures 3-2 and 3-3 provide relevant drawings of the Mayo MWIS. Figure 3-4 provides details of the
MWIS traveling screens.
13

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
wmerr.emnwrtAeea lRo coal mle camncnnk
OfM&AN Cpata410mit
wasg0eains Xeiect,eahwash,Neu[glixatlon
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co!Tn.-7 Mayo Stwm Station
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(W DAW) Forowl3lc SO%) Pumpf lOe1007f) Flow Wagram of
water tiediracta and Prowl wastewater
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Effluent Structure wre3 3w 0 FACma
I •outfall eoz/ u. ip
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1
MAYO RESERVOIR
Figure 3-1. Mayo Water Balance Diagram
14

316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
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Figure 3-2.Plan View of MWIS at Mayo
15

316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
M.*Sin COMM MART APIAP-OPARATS
1 grvar PrJAI.,.
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Figure 3-3.Section View of MWIS at Mayo
, I
1 1
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16

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
:-,f•
N-UNC CM
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Figure 3-4.Traveling Screen Design of Mayo MWIS
3.2 Latitude and Longitude of MWIS [§122.21(r)(3)(ii)]
The approximate latitude and longitude (in degrees, minutes, and seconds)of Mayo's MWIS is:
• Latitude:36° 31'41.6" N
• Longitude: 78°52' 55.8"W
3.3 Description of MWIS Operation [§122.21(r)(3)(iii)]
Withdrawal from Mayo Reservoir is dependent on makeup water demand, maximum pump capacity,
and water loss due to evaporation, plant processes, and system losses. Cooling tower makeup water
demand is directly related to the operation of generating units with the highest makeup commensurate
with high cooling tower evaporation rates during the summer months.
Operation of the MWIS consists of only one of the two makeup pumps withdrawing water from Mayo
Reservoir at any one time. During the 2016-2020 period,the MWIS daily average withdrawal was 7.16
MGD with a maximum daily withdrawal of 23.0 MGD. Note that the maximum daily withdrawal was less
than the single maximum pump capacity of 24.2 MGD.
17

316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
3.4 Description of Intake Flows [§122.21(r)(3)(iv)]
Monthly average water withdrawals during the 2016-2020 period are provided in Table 3-1. The average
withdrawal for this period was 7.16 MGD compared to a DIF of 24.2 MGD.
Table 3-1. Mayo MWIS Monthly Total Withdrawals from 2016-2020.
Month 2016 2017 2018 2019 2020
January 278.1 204.3 304.1 244.6 81.8
February 209.4 163.2 128.0 94.9 103.2
March 125.9 236.2 120.0 121.5 129.0
April 144.3 109.2 271.2 17.4 83.7
May 231.6 130.5 281.8 197.2 85.2
June 313.8 338.4 370.2 339.9 214.5
July 360.2 485.1 376.0 335.1 290.2
August 364.9 478.6 370.8 295.7 301.3
September 376.2 170.4 237.9 401.1 125.7
October 195.6 221.3 37.8 222.0 67.0
November 224.4 96.6 51.0 206.7 64.8
December 200.6 279.0 351.5 167.7 85.9
Annual
Average 8.3 7.9 7.9 7.2 4.4
Units = MG for monthly total, MGD for annual average
3.5 Engineering Drawings of CWIS [§122.21(r)(3)(v)]
The following engineering drawings of the Mayo MWIS are provided in Appendix B:
• Drawing S-2300: Cooling Tower Make Up Water Intake Structure Plan Sheet 1
• Drawing S-2302: Cooling Tower Make Up Water Intake Structure Plan &Sections Sheet 3
• Drawing CH1381-101: General Arrangement Traveling Water Screen
18

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
4 Source Water Baseline Biological Characterization
Data [§122.21(r)(4)]
The information required to be submitted per 40 CFR §122.21(r)(4), Source Water Baseline Biological
Characterization, is outlined as follows:
(i) A list of the data supplied in paragraphs (r)(4)(ii)through (vi) of this section that are not
available and efforts made to identify sources of the data;
(ii) A list of species (or relevant taxa)for all life stages and their relative abundance in the
vicinity of CWIS;
(iii) Identification of the species and life stages that would be most susceptible to impingement
and entrainment;
(iv) Identification and evaluation of the primary period of reproduction, larval recruitment, and
period of peak abundance for relevant taxa;
(v) Data representative of the seasonal and daily activities of biological organisms in the vicinity
of CWIS;
(vi) Identification of all threatened, endangered, and other protected species that might be
susceptible to impingement and entrainment at a cooling water intake structure(s);
(vii) Documentation of any public participation of consultation with Federal or State agencies
undertaken in development of the plan;
(viii) Methods and QA procedures for any field efforts;
(ix) In the case of the owner or operator of an existing facility or new unit at an existing facility,
the Source Water Baseline Biological Characterization Data is the information included in (i)
through (xii);
(x) Identification of protective measures and stabilization activities that have been
implemented, and a description of how these measures and activities affected the baseline
water condition in the vicinity of CWIS;
(xi) List of fragile species as defined at 40 CFR 125.92(m) at the facility; and
(xii) Information submitted to obtain incidental take exemption or authorization for its cooling
water intake structure(s)from the U.S. Fish and Wildlife Service or the National Marine
Fisheries Service.
Each of these requirements is described in the following subsections.
19

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
4.1 List of Unavailable Biological Data [§122.21(r)(4)(i)]
The biological data needed to prepare the information required under 40 Code of Federal Regulations
(CFR) §122.21(r)(4) are available. The historical data reviewed to develop the baseline biological
characterization of the source waterbody, Mayo Reservoir includes the following:
• Mayo Environmental Monitoring data 2015-2019(DEP 2016-2020).
These data were compiled and analyzed for this report and are summarized below. This report was
developed utilizing the relevant existing data for Mayo Reservoir. No impingement or entrainment
studies were performed in support of the development of this compliance document.
4.2 List of Species and Relative Abundance in the vicinity of CWIS
[§122.21(r)(4)(ii)]
Seasonal boat electrofishing(four times annually)surveys were conducted along six transects within
Mayo Reservoir during the study period (Figure 4-1). Each transect was surveyed using a Smith Root
equipped,Wisconsin design electrofishing boat with pulsed DC current for 15 minutes per survey event.
Collected fish were identified to the species level when possible using regional taxonomic references
(Menhinick 1993,Jenkins and Burkhead 1994), measured for total length (TL)to the nearest millimeter,
and weighed to the nearest gram. Fish that could not be accurately identified in the field were
preserved with 10 percent buffered formalin solution and transported to the laboratory for
identification and body measurements. Each specimen was examined for hybridization,anomalies,
disease, parasites,and general condition. Photographs were also taken of fish with any deformity or
anomaly. Some specimens were retained for identification in the laboratory.
20

316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
VIRGINIA io Creek
.__. . _.. .. _ NORTH CAROLINA May°eke RQ __..
N
A Outhin+
002
B B3
gbio ••
Plant
0 0.5 1 2 Miles
r r l site / y9hA
t Intake 3,)
0 0.75 1.5 3 Kilometers /Structure / '�,r
Sampling Locations:
O Water Quality
Water Chemistry
Elactrofishing +o
Transects a 1
aRa 1.
cos('
Public Boat Ramp
tit
�G
1 G3
A "`"
1_--.--_ -_ hutch Rd
Mayo Steam wsOn 11
Electric Plant
NORTH CAROLINA `._ '..
C—"
Figure 4-1. Mayo Reservoir electrofishing survey transects.
In total 5,449 fish, representing 23 species (excluding hybrids and unidentified individuals), were
collected by boat electrofishing in Mayo Reservoir from 2015 to 2019. Dominant species included
i
21

316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Bluegill (50.2%), Redear Sunfish (17.2%), Largemouth Bass (11.6%) Gizzard Shad (7.5%), Green Sunfish
(5.8%), and Chain Pickerel (3.5%) (Table 4-1). The fish community composition for each survey year
(2015 - 2019) was similar. Annual mean catch rate (fish/hour) was slightly variable for the dominant
species (Table 4-2).
Table 4-1.Total number and community composition(%)of fish collected by boat electrofishing in Mayo
Reservoir,2015-2019.
Scientific Name Common Name Total Number Composition
Alosa aestivalis Blueback Herring 12 0.2
Ameiurus brunneus Snail bullhead 2 <0.1
A.catus White catfish 2 <0.1
A.natalis Yellow bullhead 7 0.1
A.nebulosus Brown bullhead 21 0.4
A.platycephalus Flat bullhead 45 0.8
Catostomus commersonii White sucker 1 <0.1
Cyprinella analostana Satinfin Shiner 1 <0.1
Cyprinus carpio Common Carp 13 0.2
Dorosoma cepedianum Gizzard Shad 410 7.5
Erimyzon oblongus Creek Chubsucker 2 <0.1
Esox niger Chain Pickerel 185 3.4
Gambusia holbrooki Eastern Mosquitofish 1 <0.1
Ictalurus punctatus Channel Catfish 1 <0.1 _
Lepomis auratus Redbreast Sunfish 1 <0.1
L.cyanellus Green Sunfish 318 5.8
L.gulosus Warmouth 64 1.2 _
L.macrochirus Bluegill 2736 50.2
L.microlophus Redear Sunfish 936 17.2
Micropterus salmoides Largemouth Bass 632 11.6
Moxostoma collapsum Notchlip Redhorse 4 0.1
Notemigonus crysoleucas Golden Shiner 2 <0.1
Pomoxis nigromaculatus Black Crappie 53 1.0
22

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Table 4-2.Total number(n),composition(%),and relative abundance(fish/hour-CPUE)of fish collected by boat electrofishing in Mayo Reservoir,2015-
2019. (NC=No catch)
2015 2016 2017 2018 2019
Common Name Scientific Name n % CPUE n % CPUE n % CPUE n % CPUE n % CPUE
Blueback Herring Alosa aestivalis NC 1 0.1 0.2 11 0.8 1.8 NC NC
Snail Bullhead Ameiurus brunneus NC NC NC NC 2 0.2 0.3
White Catfish A.catus 1 0.1 0.2 NC NC NC 1 0.1 0.2
Yellow Bullhead A.natalis 3 0.3 0.5 1 0.1 0.2 3 0.2 0.5 NC NC
Brown Bullhead A.nebulosus 4 0.3 0.7 6 0.6 1.0 3 0.2 0.5 3 0.3 0.5 5 0.5 0.8
Flat Bullhead A.platycephalus 14 1.2 2.3 11 1.0 1.8 13 0.9 2.2 4 0.5 0.7 3 0.3 0.5
White Sucker Catostomus commersonii NC NC NC NC 1 0.1 0.2
Satinfin Shiner Cyprinella analostana NC NC 1 0.1 0.2 NC NC
Common Carp Cyprinus carpio 5 0.4 0.8 2 0.2 0.3 4 0.3 0.7 NC 2 0.2 0.3
Gizzard Shad Dorosoma cepedianum 66 5.6 11.0 74 6.9 12.3 126 9.0 21.0 71 8.2 11.8 73 7.9 12.2
Creek Chubsucker Erimyzon oblongus NC 2 0.2 0.3 NC NC NC
Chain Pickerel Esox niger 59 5.0 9.8 53 4.9 8.8 33 2.3 5.5 16 1.8 2.7 24 2.6 4.0
Eastern Mosquitofish Gambusia holbrooki NC NC 1 0.1 0.2 NC NC
Channel Catfish Ictalurus punctatus NC NC 1 0.1 0.2 NC NC
Redbreast Sunfish Lepomis auritus NC NC 1 0.1 0.2 NC NC
Green Sunfish L.cyanellus 87 7.4 14.5 55 5.1 9.2 64 4.5 10.7 32 3.7 5.3 80 8.7 13.3
Warmouth L.gulosus 17 1.5 2.8 17 1.6 2.8 14 1.0 2.3 8 0.9 1.3 8 0.9 1.3
Bluegill L.mocrochirus 670 57.3 111.7 619 57.3 103.2 706 50.2 117.7 389 44.8 64.8 352 38.1 58.7
Redear Sunfish L.microlophus 89 7.6 14.8 112 10.4 18.7 258 18.3 43.0 235 27.0 39.2 242 26.2 40.3
Largemouth Bass Micropterus salmoides 141 12.1 23.5 117 10.8 19.5 155 11.0 25.8 97 11.2 16.2 122 13.2 20.3
Notchlip Redhorse Moxostoma collapsum NC 2 0.2 0.3 NC NC 2 0.2 0.3
Golden Shiner Notemigonus crysoleucas NC 1 0.1 0.2 NC 1 0.1 0.2 NC
23

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
2015 2016 2017 2018 2019
Common Name Scientific Name n % CPUE n % CPUE n % CPUE n % CPUE n % CPUE
Black Crappie Pomoxis nigromaculatus 14 1.2 2.3 7 0.6 1.2 13 0.9 2.2 13 1.5 2.2 6 0.7 1.0
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4.2.1 Exotic Species
Common Carp(Cyprinus carpio)was the only Exotic Species (USGS 2020) collected during the study
period and only represented 0.2%of the individuals collected (Table 4-1).
4.3 Primary Growth Period
Fish are cold blooded,thus primary growth occurs when water temperatures are 10°C or above. The
conventional view on seasonal variation in fish growth in North America is that growth is fastest in the
spring and early summer,slows in the late summer and fall, and virtually stops in the winter(Gebhart
and Summerfelt 1978). The majority of fishes will have their highest densities shortly after the hatch
occurs when larvae are concentrated, and natural mortality has not yet reduced numbers. Feeding
competition is especially important during late spring through early summer when the bulk of fish are in
their early life stages. During this time,they are more susceptible to starvation (May 1974). This is a
critical stage in development,where larval fish have a short time period to initiate exogenous feeding
before starving(Ehrlich 1974; Miller et al. 1988).
4.3.1 Reproduction and Larval Recruitment
Spawning and recruitment details for fish species collected in Mayo Reservoir are described in detail in
Table 4-3 and 4-4. Most of the fish species collected prefer a spring—early summer spawning period.
During this time period, egg and larval fish in the vicinity of the Mayo MWIS are most susceptible to
entrainment.
Table 4-3. Known Spawning and Recruitment Period of Fish Collected in Mayo Reservoir from 2015-2019
(Jenkins and Burkhead 1993;Rohde et al.2009). [Lighter shade indicates the spawning window while the darker
shading indicates the peak spawning period]
Common Name Jan Feb Mar ' Apr May Jun Jul Aug Sep Oct Nov Dec
Blueback Herring
Snail Bullhead
White Catfish
Yellow Bullhead
Brown Bullhead
Flat Bullhead
White Sucker
Satinfin Shiner
Common Carp
Gizzard Shad
Creek P ere --.,.
Chain Pickerel
kerel
Eastern Mosquitofish
Channel Catfish
Green Sunfish
Warmouchuth
Bluegill
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Common Name Jan Feb Mar Apr May Jun ® Aug Sep Oct Nov Dec
Redbreast Sunfish
Redear Sunfish
Largemouth Bass
Notchlip Redhorse Golden Shiner
Black Crappie
Table 4-4.Seasonal and Daily Activities of Species Collected in Mayo Reservoir from 2015-2019(Jenkins and
Burkhead 1994;Rohde et al.2009).
Species
(Common Seasonal Activities(Spawning) Daily Activities(Feeding and Habitat)
Name)
Blueback Land locked populations of Inhabits pelagic portion of water bodies. Feeds primarily
Herring Blueback Herring spawn during the on plankton.
spring. Eggs appear to be
adhesive during the water
hardening period but become
detached and suspend in the water
column where sufficient turbulence
occurs.
Snail Spawning occurs from May thru Inhabits warm, medium and large rivers, reservoirs in
Bullhead July starting at temperatures of near-shore habitats, associates with cover such as large
21°C in May. Large nests are rock, logs, fallen trees. Feeds on aquatic invertebrates
constructed on bottom in sand or and fish, omnivorous feeding on aquatic invertebrates
gravel, near or in fallen tree and and fishes.
logs, eggs are then guarded by
males.
White Spawning occurs from May into Inhabits warm ponds, reservoirs, medium and large
Catfish July depending on seasonal rivers. Young and juveniles predominantly feed on
conditions. Sizeable spawning aquatic insects. Adults are omnivorous, consuming a
nest are constructed with sand and variety of aquatic invertebrates, fishes and plants.
gravel in approximately 0.3-0.5
meters of water.
Yellow Spawning occurs from April Inhabits pools and backwaters of lotic habitats and in
Bullhead through June. Spawning occurs in ponds, lakes, and reservoirs. Typically, are associated
shallow circular nests excavated with cover, often dense vegetation. Young feed primarily
near cover or in open settings, in on microcrustaceans and insect larvae.Adults are
calm water. omnivorous but mainly eat various aquatic invertebrates
and fishes.
Brown Spawning begins in April and may Inhabits backwaters of pools of moderate-gradient and
Bullhead continue through late summer sluggish large creeks, streams, and rivers, and of ponds,
when water temperatures are lakes, and reservoirs. Omnivorous feeder where young
between 14-29°C. Nest occur in feed on a variety of microcrustaceans and adults feed on
shallows, in the open, in natural algae, a broad spectrum of aquatic invertebrates, and
shelters such as under logs and fishes.
burrows and in litter.
Flat Bullhead Similar to Snail Bullheads, Similar to the Snail Bullhead, inhabits warm, medium and
spawning occurs in May and June large rivers, reservoirs in near-shore habitats, associates
at peaking at temperatures with cover such as large rock, logs, fallen trees. Feeds
between 21 -24°C in May. on aquatic invertebrates and fishes.
Assumed to construct nests and
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Species
(Common Seasonal Activities(Spawning) Daily Activities(Feeding and Habitat)
Name)
guard eggs similar to other
Bullhead catfishes.
White Sucker Spawning occurs between late- Inhabits moderate and high gradient, un-silted and
March and much of July when heavily silted creeks and streams. Large juvenile and
temperatures are between 15— adults occupy pools that are fairly deep or that have
23°C. Spawning typically occurs structural shelter. Feeds chiefly on midge larvae and
riffles of largely gravel in large small crustaceans., and to a lesser extent on other
creeks to large rivers. Fecundity aquatic insects, other arthropods, snails, finger clams,
ranges from 20,000- 139,000 ova. other invertebrates and fish eggs. _
Satinfin Spawning occurs between May Typically inhabit warm medium-sized streams to major
Shiner and mid-August when rivers of moderate to low gradient. Can be found in
temperatures are between 18— pools, backwaters, and runs of shallow to moderate
30°C. Fractional spawners that depth over a variety of substrates. Opportunistic feeder
deposit eggs in crevices of wood particularly on drifting items, principally,
and other structures. microcrustaceans,terrestrial and aquatic insects and
algae.
Common Spawning occurs in the spring in Tolerant of a wide range of environmental conditions.
Carp the shallow water and along Typically found in the calm and mud-bottomed waters of
shorelines in reservoirs, over sluggish pools, backwaters, and reservoirs where
vegetation,tree roots, or open vegetation is present. Common Carp are omnivores.
bottom, peak spawning occurs They ingest mouthfuls of the soft bottom sediments
between 15 and 20°C and usually (detritus), expels them into the water, and then feed on
when aquatic vegetation is flooded the disclosed insects, crustaceans, annelid worms,
during April and May. Spawning mollusks,weed and tree seeds, aquatic plants, and
activities create lots of turbidity, algae.
eggs attach to vegetation or sink
into the mud. Fecundity for large
females can be over 2,000,000
ova.
Gizzard Shad Spawning occurs from March to Inhabits a variety of habitats but is considered a pelagic
August, usually between April and schooling fish. Filter feeder, using numerous fine gill
June. Spawning occurs in sloughs, rakers to strain plankton from the water column and
ponds, lakes, and reservoirs, occasionally from the bottom.
usually at near-surface depths
ranging from 0.3- 1.6 meters.
Sometimes spawning can occur
over vegetation or debris.
Creek Spawning typically occurs from Inhabits ditches, creeks to rivers, and natural and
Chubsucker late-March into May. Spawning artificial ponds and lakes. Often found on soft and firm
typically occurs over sand and bottoms and less associated with submersed vegetation.
gravel in 0.5- 1.2 meters of water. Feeds primarily on microcrustaceans, aquatic insects,
mollusk, algae and detritus.
Chain Spawning occurs from January— Inhabits clear, cool and warm, sluggish creeks, rivers,
Pickerel March when water temperatures ditches, natural and artificial ponds, and lakes that are
range from 2-22°C. Spawning well vegetated. Generally found in water less than 3
activity typically occurs in shallow meters deep. Young feed primarily on fish, small
water up to 3 meters, usually crustaceans, and insects. Adults feed primarily on fish.
among submerged vegetation.
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Species
(Common Seasonal Activities(Spawning) Daily Activities(Feeding and Habitat)
Name)
Eastern Spawning occurs during the warm Inhabits a wide range of conditions, but favors vegetated
Mosqutiofish months of the year. Prolific areas of lakes, oxbows, ponds, drainage ditches,
livebearer.The number per brood sloughs, and backwaters of creeks and rivers over a soft
ranges proportionally to the size of substrate of mud or and. Feeds primarily on surface
the female,typically one to more dwelling aquatic insects and their larve.
than 300.
Channel Spawning occurs from May through Inhabit lakes, rivers, streams occupying a variety of
Catfish July, between 21 and 30°C, nests habitats and substrates. Young feed primarily on
are constructed in sheltered areas. plankton and insect larvae and larger fish eat almost any
available food items including other fish.
Green Spawning occurs April through Inhabit slow pools and backwaters of low-and moderate
Sunfish August, constructs nests in gradient streams and rivers, but also occur in ponds,
colonies as shallow depressions in lakes, and reservoirs. Highly tolerant of conditions such
sand and gravel in pools in sand as turbidity and drought and can rapidly colonize new
and gravel near shelter such as habitats. Food preferences are aquatic insects and small
logs and vegetation, males guard fishes. Frequently associated with vegetation and large
eggs in nests. rocky areas or rip-rap shorelines.
Warmouth Spawning occurs from mid-spring Inhabits pools and backwaters, swamps, lakes, and
into summer, occasionally early frequently associates with aquatic vegetation, and large
fall, starts spawning at 21°C. rocky areas, commonly associates with rip-rap shorelines
Males construct a solitary nest in reservoirs. Young feed on plankton and small insects
often hidden in vegetation and while adults eat insects, snails, crayfishes, and fishes.
guard eggs.
Bluegill Spawning occurs from May through Inhabits pools, lakes, streams, and rivers,with
September, generally most of the vegetation, overhead cover, structure. Young are
growing season, peaking in June. planktivores, adults eat aquatic and terrestrial insects.
Fish construct nests in
aggregations in shallow water on
sand or gravel bottoms, eggs are
guarded by male.
Redbreast Spawning occurs from June thru Inhabits pool habitat, lakes, and rivers, associates with
Sunfish August between 16-28°C. Nests woody debris, stumps, and undercut banks, abundant in
are constructed over sand and upstream reaches of reservoirs, rip-rap shoreline, and
gravel, often with overhead cover, rocky points. A generalist predator that eats insects,
eggs are adhesive and can form crayfish, arthropods, mollusks, and fishes.
large clumps in the nest, males
guard eggs in the nest.
Redear Generally, spawning occurs from Inhabits lacustrine ecosystems, generally found in
Sunfish April through August,with the vegetated lakes, ponds, reservoirs, streams, rivers, or
onset of temperatures between 20 backwater areas. Generally, feeds on small prey, snails,
-21°C. Nests found in aggregate and small mussels and clams, small insects and fishes.
and are constructed in waters
shallower than 2 meters, often near
vegetation and in colonies, males
guard eggs in the nest.
Largemouth Spawning occurs late April to June Inhabits a wide variety of habitats. Prefer warm, calm,
Bass when temperatures are between 16 and clear water and thrive in slow streams, farm ponds,
- 18°C,with peak spawning lakes, and reservoirs.Young feed primarily on plankton,
occurring in April and May. Nests insects, small fishes, adults feed on fishes, frogs, and
are generally located in sand or almost any other animal of appropriate size.
gravel at the base of logs, stumps,
and emergent vegetation along
shorelines usually at depths of 0.6
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Species
(Common Seasonal Activities(Spawning) Daily Activities(Feeding and Habitat)
Name)
meters. Both male and female
guard eggs in nest.
Notchlip Spawning occurs in April and May Inhabits large streams, small to big rivers, and natural
Redhorse when water temperatures range and artificial lakes. Feeds on insect larvae,
from 11 - 15°C. Spawning is microcrustaceans, crayfishes, mollusks, algae and
typically associated with shallow detritus.
riffles over_gravel and rubble.
Golden Spawning may occur from April Inhabits open water and along edges of weedy habitat,
Shiner thru August, from 15-26°C. moves from shallow inshore areas to open waters
Adhesive eggs are cast over rooted following plankton migrations. Feeds primarily from
aquatic vegetation, filamentous midwater to surface depths on plankton,
algae, gravel, and sometime on microcrustaceans, and insects, sometimes algae.
nests of black basses and
sunfishes.
Black Spawning occurs from late Inhabits vegetated areas of backwaters in streams and
Crappie February to early June. Nests are rivers in ponds and reservoirs, aggregates around
constructed in shallow water to structure and associates with aquatic vegetation, fallen
moderately deep water(to 6 trees, stumps. Young Black Crappie feed on aquatic
meters), sometimes in close insects and small fishes and adults feed primarily on
proximity to each other and usually fishes.
associated with vegetation or
structure, larvae are pelagic and
move inshore as larr erjuveniles.
4.4 Species and Life Stages Susceptible to Impingement and
Entrainment
The MWIS design,with a TSV of less than 0.5 fps at normal Mayo Reservoir pool elevation, is compliant
with impingement BTA requirements of the Rule. As such, no species or life stages are anticipated to be
susceptible to impingement at the Mayo MWIS(Table 4-5). While some species may have the potential
to be entrained, based on the operational parameters of the MWIS within Mayo Reservoir(low DIF, low
AIF, and low TSV), interactions with aquatic organisms are expected to be limited, with no potential for
adverse environmental impacts.
4.4.1 Impingement
The degree of vulnerability to impingement exhibited by adult and juvenile fish species depends upon
biological and behavioral factors including seasonal fish community structure, spawning effects on
distribution, habitat surrounding intake structures, high flow events, and attraction to the flow
associated with the intake. In addition,swimming speed, intake velocity, screen mesh size,trash rack
spacing, and other intake configurations will also affect the susceptibility to impingement. For example,
clupeids have high susceptibility to impingement based on multiple factors such as schooling behavior,
distribution in the water column, negative rheotactic response to intake flows, and poor swimming
performance in winter months due to lower water temperatures (Loar et al 1978).
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No ongoing or historical impingement studies have been performed at Mayo. The MWIS withdraws
water from Mayo Reservoir through coarse-mesh screens with a TSV of less than 0.5 fps at normal pool
elevation. In the Rule,screens designed to achieve a TSV at or below 0.5 fps are compliant with the
impingement reduction standard.
4.4.2 Entrainment
Ichthyoplankton (the egg and larval life stage of fishes)exhibit the highest degree of susceptibility to
entrainment based on body size and swimming ability. Therefore, an organism is most susceptible to
entrainment for a portion of its life cycle. Larger juvenile and adult life stages have the swimming ability
to avoid entrainment. Life history characteristics can influence the vulnerability of a fish species to
entrainment. For example, broadcast spawners with non-adhesive,free-floating eggs can drift with
water currents and may become entrained in a MWIS,while nest-building species with adhesive eggs
are less susceptible to entrainment during early life stages.
When considering the spawning preference of the species present in Mayo Reservoir(Table 4-5)and the
habitat in the immediate vicinity of the MWIS (described as steep sided and deep,surrounded by rip-rap
Figure 4-2),this area is not preferred spawning habitat. These factors alone result in a low entrainment
potential for eggs and larvae.
•
Figure 4-2.Aerial View of the MWIS within Mayo Reservoir.
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Table 4-5. Entrainment Potential for Fish(Egg and Larvae)Species Present near the Mayo MWIS.
Species Spawning Habitat Potential for Entrainment'
(Common Name) Use/Preference
Blueback Surface open water spawner. Possible due to the habitat around the MWIS and
Herring Eggs are essentially pelagic. The spawning behavior.
eggs appear to be adhesive
during the water-hardening period
but become detached and
susjDended in the water column.
Snail Bullhead Cavity nesters. Unlikely due to habitat and spawning preference, and
low abundance.
White Catfish Cavity nesters. Unlikely due to habitat and spawning preference, and
low abundance.
Yellow Bullhead Cavity nesters. Unlikely due to habitat and spawning preference, and
low abundance.
Brown Bullhead Cavity nesters. Unlikely due to habitat and spawning preference, and
low abundance.
Flat Bullhead Cavity nesters. Unlikely due to habitat and spawning preference, and
low abundance.
White Sucker Upstream spawning migration. Unlikely due to habitat and spawning preference, and
Typical spawning occurs over low abundance.
riffles of large creeks to large
rivers. Demersal eggs.
Satinfin Shiner Fractional spawners that deposit Unlikely due to habitat and spawning preference, and
adhesive eggs in crevices of wood low abundance.
and other structures.
Common Carp Lays adhesive eggs in shallow Unlikely due to habitat and spawning preference, and
vegetation. low abundance.
Gizzard Shad Random, aggregate, shallow Possible due to the habitat around the MWIS and
water surface spawners. spawning behavior.
Adhesive eggs
Creek Spawns over sand and gravel in Unlikely due to habitat and spawning preference, and
Chubsucker shallow water. low abundance.
Chain Pickerel Spawns along vegetated substrate Unlikely due to habitat and spawning preference, and
in shallow water, approximately< low abundance.
3.0 meters.
Eastern Live barer with internal Unlikely due to life history requirements, and low
Mosquitofish fertilization. abundance.
Channel Catfish Cavity nesters,found in large Unlikely due to habitat and spawning preference, and
open areas with woody debris, low abundance.
bank cavities; moderate currents.
Green Sunfish Construct nests around Unlikely due to habitat and spawning preference, and
vegetation. low abundance.
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Species Spawning Habitat Potential for Entrainment'
(Common Name) Use/Preference
Warmouth Construct nests in cover. Unlikely due to habitat and spawning preference, and
low abundance.
Bluegill Nest generally constructed in Possible due to species abundance.
shallow waters.
Redbreast Construct nests over silt-free or Unlikely due to habitat and spawning preference, and
Sunfish lightly silted sand and gravel in low abundance.
cover.
Redear Sunfish Nest generally constructed in Unlikely due to habitat and spawning preference,
shallow waters. demersal and adhesive eggs, parental care of nest
until larvae swim-up.
Largemouth Nest constructed in shallow areas Unlikely due to water depth in the vicinity of the
Bass of 0.3-2 meters. MWIS.
Notchlip Spawning occurs in shallow riffles Unlikely due to habitat and spawning preference, and
Redhorse over gravel and rubble. low abundance.
Golden Shiner Adhesive eggs are cast over Unlikely due to habitat and spawning preference,
rooted aquatic vegetation, adhesive and demersal eggs, relatively low
filamentous algae, gravel, and abundance.
sometime on nests of black
basses and sunfishes, schools in
open water and along edges of
weedy habitat.
Black Crappie Construct nests around vegetation Unlikely due to habitat and spawning preference,
close to other nests. demersal and adhesive eggs, parental care of nest
until larvae swim-up, and low abundance.
1TSV below 0.5 fps at the MWIS will minimize potential for entrainment for all species based on their ability for avoidance of the
intake. Species with floating eggs would continue to have some susceptibility to entrainment.
4.4.3 Selected Species
A subset of species present(dominant species) in Mayo Reservoir with the highest likelihood to be
entrained was selected for detailed life history descriptions including reproduction, recruitment,and
peak abundance as detailed in excerpts from Freshwater Fishes of Virginia (Jenkins 1993). The habitat in
the immediate vicinity MWIS is described as steep sided and deep, surrounded by riprap. Most fish
species are using the vicinity of the MWIS for staging or foraging. Of the species present, Bluegill,
Gizzard Shad, and Blueback Herring have the highest likelihood of being entrained based on species
abundance(Bluegill) and spawning preference (Gizzard Shad and Blueback Herring).
Bluegill
Bluegill are native to the Great Lakes-St. Lawrence and Mississippi basins,the Atlantic slope probably
from North Carolina southward, and the Gulf slope west to Texas. It is the most widely introduced
species of Sunfish (Jenkins 1993). Bluegills are found in pools and backwaters of low to moderate-
gradient creeks,streams, and rivers, and in all types of lacustrine habitats. The Bluegill occupies clear
and turbid waters, hard and silted substrates (Grahm and Hastings 1984). Spawning likely occurs from
May to August or September.
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Spawning typically occurs over nest constructed by males in shallows on sand or gravel; nest frequently
occur in colonies (Coggeshall 1924, Crowe 1959, and Gross and MacMillan 1981). Bluegill average five
spawnings and produce about 80,000 eggs per year.
Redear Sunfish
Redear Sunfish are native to the middle and lower Mississippi basin,the Atlantic slope from Florida to
perhaps no further than Georgia,and the Gulf slope west into Texas (Bailey 1938). Predominantly a
lacustrine species, Redear Sunfish inhabits generally clear,vegetated ponds and lakes. It occurs widely in
pools and backwaters of streams with the same attributes. The onset of spawning varies by latitude,
generally occurring in the spring when water temperatures approach 21°C. Spawning normally ends by
mid-summer but extends into October in some southern states (Wilbur 1969 and Carlander 1977).
Spawning typically occurs over nest constructed in water shallower than 2 meters. Often, nest occur
near vegetation and in colonies. Males make a grunting sound during courtship (Gerald 1971).
Estimates of mature ova per female are 15,001-30,144 (Wilbur 1969).
Largemouth Bass
Largemouth Bass are native to the Great Lakes-St. Lawrence and Mississippi basins and the Gulf and
south Atlantic slopes; both subspecies have been widely transplanted in North American and beyond
(Robbins and MacCrimmon 1974). Largemouth Bass inhabits marshes, swamps, ponds, lakes, reservoirs
(like Mayo), and creeks to large rivers. Largemouth Bass prefer warm,generally clear water, and are less
tolerant of turbidity than the Spotted Bass (Trautman 1981). Spawning occurs in the spring(May and
June)when water temperatures approach 16- 18°C and continue to 24°C(Carlander 1977).
Males fan out a nest and guard it against intruders; sometime spawning occurs on unprepared bottoms.
Nests are made on a variety of substrates in pools and backwaters of streams and along the shores of
ponds and reservoirs at a depth of 0.3 -0.6 meters typically, but up to 8.2 meters deep(Carlander 1977).
Nests may be found in open settings or in association with ledges, logs, or aquatic macrophytes, and
may be well spaced or crowded.
Green Sunfish
Green Sunfish are native to the Great Lakes and Mississippi basins and the Gulf slope and have been
widely distributed elsewhere. Green Sunfish occupy slow pools and backwaters of moderate-gradient,
clear and turbid creeks, streams, and rivers, and of ponds lakes and reservoirs. It is strictly a freshwater
fish (Musick 1972). Spawning typically begins in April and could extend into August.
Males construct nest in pools and backwaters, often near vegetation. The territorial males produce a
grunting sound during courtship and spawning(Gerald 1971). Females are moderately fecund, bearing
2,000- 10,000 ova (Beckman 1952).
Gizzard Shad
Gizzard Shad are native to the Atlantic and Gulf Slopes and to interior drainages of eastern and central
North America. The Gizzard Shad is characterized as a pelagic,schooling fish that occurs in a variety of
habitats. It inhabits pools and runs of medium streams to rivers of low or moderate gradient, and
populates reservoirs, lakes,swamps,floodwater pools, estuaries, brackish bays, and occasionally,
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marine waters (R. R. Miller 1960, 1964). Spawning typically occurs from March through August(Miller
1960).
Spawning occurs in freshwater sloughs, ponds, and reservoirs, usually at near-surface depths (0.3- 1.6
meters) but sometimes as deep as 15 meters, and sometimes over vegetation or debris (Gunter 1938,
Miller 1960, Shelton and Grinstead 1973,Jones et al. 1978, Wang and Kernehan 1979). Spawning
groups swim near the surface and roll about a mass, releasing egg and sperm (Miller 1960). Eggs are
demersal and adhere to algae, rocks, or other objects (R. R. Miller 1960, 1964). Fecundity ranges from
22,400-543,910 ova (Bodola 1966,Schneider 1969).
Blueback Herring
Blueback Herring range from Cape Brento, Nova Scotia,to the St.Johns River Florida (Hildebrand and
Schroeder 1928, Bigelow and Schroeder 1953). Blueback Herring have been transported by anglers and
State agencies resulting in landlocked reproducing populations. Blueback Herring is described as a
typical pelagic-schooling river herring. Landlocked populations spawn during spring(D. K. Whitehurst,
personal communication).
During spawning, a female and two or males swim circularly at about one meter from the surface.
Swimming speed gradually increases and the group dives to the bottom, releasing gametes (Loesch and
Lund 1977). The eggs settle in still water but are essentially pelagic(Kuntz and Radcliffe 1917, Lippson
and Moran 1974). The eggs appear to be adhesive during the water-hardening period but become
detached and suspended in the water column where sufficient turbulence occurs(Loesch and Lund
1977).
Chain Pickerel
Chain Pickerel are native to the Atlantic slope from New England to Florida,the Gulf slope,and the
lower central Mississippi Valley. Chain Pickerel are solitary fish,found typically in cool and warm,
sluggish creeks, rivers, ditches, natural and artificial ponds, and lakes that are well vegetated. Chain
Pickerel are coldwater spawners. Spawning may last only 7-10 days in any one water body of water at 2
-22°C; peak spawning occurs in the middle of that range of temperatures(Scott and Crossman 1973,
Guillory 1979, 1984,Wang and Kernehan 1979).
Reproductive activity occurs in lakes and calm stream shallows at depths to three meters, usually among
submerged vegetation. A female and one or two males swim together for a day or two, periodically
rolling inward, bringing their vents close together. Eggs and milt are shed simultaneously, and mixed
and dispersed by purposeful undulations of the tail (Kendall 1917,Scott and Crossman 1973). The
number of ripe eggs produced is 342—8,140(Scott and Crossman 1973, Guillory 1979, 1984).
4.5 Threatened, Endangered, and Other Protected Species
Susceptible to Impingement and Entrainment at the MWIS
The Rule requires the permittee to document the presence of federally listed species and designated
critical habitat in the action area (see 40 CFR 125.98[f]). For the purpose of defining listed species,the
action area is defined as a one-mile radius around the Mayo MWIS.
A desktop review of available resources was performed to develop a list of species with protected,
endangered, or threatened status that might be susceptible to impingement and entrainment at the
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MWIS on Mayo Reservoir. The USFWS's map-based search tool (Information for Planning and
Consultation [IPaC])was used to identify state or federally listed rare,threatened, or endangered (RTE)
aquatic species or critical habitat designations within the defined search area. Listed species spatial
occurrence data from the North Carolina Natural Heritage Program was cross-referenced spatially
relative to the Mayo MWIS. Because the Mayo MWIS is in a freshwater environment, marine and
anadromous federally listed species and designated critical habitat under National Marine Fisheries
Service jurisdiction were not considered.
State and federally listed rare,threatened, or endangered (RTE)aquatic species or critical habitat
designations occurring within the vicinity of the Mayo MWIS, are provided in Table 4-6. Federal species
of concern and candidate species were omitted from the list(unless they were also state threatened or
endangered), as there are no requirements to address those species under the Rule or Section 7 of the
ESA. The following materials were reviewed to develop the species list in Table 4-6:
• IPaC(https://ecos.fws.gov/ipac/) (USFWS 2020)
• North Carolina Department of Natural and Cultural Resources (NCDNCR) Natural Heritage
Program Data explorer listed species element occurrence data (NCDNCR 2021).
The Mayo Environmental Monitoring program discussed in Section 4.2 of this report resulted in no
collections of federally or state-listed species from 2015 to 2019. The UFWS IPAC search indicated that
the Atlantic Pigtoe (Fusconaia masoni) might be affected by activities in the search location (1.0-mile
circumference of the Mayo Reservoir). The Atlantic Pigtoe has no known population within Mayo
Reservoir and is highly unlikely to be present. Additionally,all other federal or state listed species were
not detected during the study period.
Surveys conducted by Duke Energy in 2004 and prior to 1986 documented the presence of Carolina
Darter and Fantail Darter in Mayo Reservoir. The abundance of these species in historical surveys was
low, resulting in the low likelihood of interaction with the Mayo MWIS.
Table 4-6.Summary of Rare,Threatened,or Endangered(RTE)aquatic species listed for the area around Mayo
Reservoir,North Carolina,and record of occurrence of potential to occur near the Mayo MWIS.
Scientific Common Federal Record of occurrence or potential to
Source Name Name Status State Status occur Near the Mayo MWIS
NCDNCR Alasmidonta Triangle n/a Threatened Unlikely as none have been collected
undulata Floater in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
NCDNCR Elliptio Box Spike n/a Poorly Known Unlikely as none have been collected
cistellaeformis in NC, Threat in the vicinity of the MWIS. Preferred
to Habitat 5 habitat is not present in the vicinity of
the MWIS.
USFWS Fusconaia Atlantic Proposed Endangered Unlikely as none have been collected
masoni Pigtoe Threatened in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
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316(b)Compliance Submittal
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Scientific Common Federal Record of occurrence or potential to
Source Name Name Status" State Status occur Near the Mayo MWIS
NCDNCR Lampsilis Yellow n/a Endangered Unlikely as none have been collected
cariosa Lampmussel in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
NCDNCR Lampsilis Eastern n/a Threatened Unlikely as none have been collected
radiata(syn. Lampmussel in the vicinity of the MWIS. Preferred
Lampsilis habitat is not present in the vicinity of
radiata radiata, the MWIS.
Lampsilis
fullerkati,
Lampsilis
radiata
conspicua)
NCDNCR Lampsilis sp. 2 Chameleon n/a Significantly Unlikely as none have been collected
Lampmussel Rare in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
NCDNCR Lasmigona Green n/a Endangered Unlikely as none have been collected
subviridis Floater in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
NCDNCR Strophitus Creeper n/a Threatened Unlikely as none have been collected
undulatus in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
NCDNCR Villosa Notched n/a Threatened Unlikely as none have been collected
constricta Rainbow in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
NCDNCR Ambloplites Roanoke n/a Significantly Unlikely as none have been collected
cavifrons Bass Rare in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
NCDNCR Etheostoma Carolina n/a Special Unlikely as none have been collected
corns Darter Concern in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
NCDNCR Etheostoma Fantail Tarter n/a Threat to Unlikely as none have been collected
f/abellare Habitat in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
NCDNCR Lythrurus Pinewoods n/a Threat to Unlikely as none have been collected
matutinus Shiner Habitat in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
36

316(b) Compliance Submittal
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Scientific Common Federal Record of occurrence or potential to
Source Name Name Status` State Status occur Near the Mayo MWIS
NCDNCR Notropis Mimic Shiner n/a Threatened Unlikely as none have been collected
volucellus in the vicinity of the MWIS. Preferred
habitat is not present in the vicinity of
the MWIS.
4.6 Documentation of Consultation with Services
In preparing this response package for compliance with the Rule, there has been neither public
participation, nor coordination undertaken with the USFWS or NMFS. Duke Energy has not submitted
information to obtain incidental take exemption or authorization from any Agency.
4.7 Incidental Take Exemption or Authorization from Services
Duke Energy has not submitted information to obtain incidental take exemption or authorization from
the Services.
4.8 Methods and Quality Assurance Procedures for Field Efforts
Data presented in this report were compiled from DEP's Mayo Environmental Monitoring Program (DEP
2015-2019). All data were collected according to NCDEQ approved procedures under the Duke Energy
Progress Biological Laboratory Certification number 006.
4.9 p
Fragile Species
g
In the Rule,the EPA identifies 14 species of fish as fragile or having post-impingement survival rates of
less than 30 percent. Occurrence of fragile species in Mayo Reservoir have been documented in the
Duke Energy Environmental Monitoring Program (Tables 4-1 and 4-7).
Table 4-7. List of fragile species as defined by the EPA and their occurrence in Mayo Reservoir.
Scientific Name Common Name Occurrence in vicinity of the
Mayo MWIS*
Alosa pseudoharengus Alewife No
Alosa sapidissima American Shad No
Clupea harengus Atlantic Herring No
Doryteuthis(Amerigo)pealeii Atlantic Long-fin Squid No
Anchoa mitchilli Bay Anchovy No
Alosa aestivalis Blueback Herring Yes
Pomatomussaltatrix Bluefish No
Poronotus triacanthus Butterfish No
Lutjanus griseus Grey Snapper No
Alosa mediocris Hickory Shad No
Brevoortia tyrannus Atlantic Menhaden No
Osmerus mordax Rainbow Smelt No
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316(b) Compliance Submittal
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Scientific Name Common Name Occurrence in vicinity of the
Mayo MWIS*
Etrumeus sadina Round Herring No
Engraulis eurystole Silver Anchovy No
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316(b)Compliance Submittal
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5 Cooling Water System Data [§122.21(r)(5)(i)]
The information required to be submitted per 40 CFR§122.21(r)(5), Cooling water system data, is
outlined as follows:
(i) A narrative description of the operation of the cooling water system and its relationship to
cooling water intake structures;the proportion of the design intake flow that is used in the system;the
number of days of the year the cooling water system is in operation and seasonal changes in the
operation of the system, if applicable;the proportion of design intake flow for contact cooling, non-
contact cooling, and process uses; a distribution of water reuse to include cooling water reused as
process water, process water reused for cooling, and the use of gray water for cooling;a description of
reductions in total water withdrawals including cooling water intake flow reductions already achieved
through minimized process water withdrawals; a description of any cooling water that is used in a
manufacturing process either before or after it is used for cooling, including other recycled process
water flows;the proportion of the source waterbody withdrawn (on a monthly basis);
(ii) Design and engineering calculations prepared by a qualified professional and supporting data to
support the description required by paragraph (r)(5)(i)of this section; and,
(iii) Description of existing impingement and entrainment technologies or operational measures and
a summary of their performance, including but not limited to reductions in impingement mortality and
entrainment due to intake location and reductions in total water withdrawals and usage.
Each of these requirements is described in the following subsections.
5.1 Description of Cooling Water System Operation
[§122.21(r)(5)(i)]
The Mayo circulating water system is a closed-loop system with cooling water recycled and reused in the
steam turbine condenser. The purpose of the circulating water system is to supply cooling water to the
main and auxiliary steam condensers. The heat transferred to the circulating water in the condenser is
rejected to the atmosphere by the evaporation process in the cooling tower. Approximately 95 percent
of water withdrawn by the MWIS is used for cooling tower makeup.
5.1.1 Cooling Water System Operation
Three circulating water pumps, each rated at 128.2 MGD (89,000 gpm) supply cooling water to the
condenser and additional circulating water to the auxiliary cooling water heat exchangers. Heated
water from these systems is returned to the cooling tower through the circulating water piping. The
heated circulating water is cooled by the cooling tower and then collected in the cooling tower basin
where it flows back to the circulation pumps, and the cycle is repeated. Mayo has one mechanical draft
counterflow cooling tower equipped with ten cooling cells, motor-driven fans, and three pumps in the
tower basin to recirculate the cooling water to the condenser. Figure 5-1 provides a schematic of the
Mayo cooling tower.
Most of water losses in the circulating water system is through evaporation in the cooling tower.
Evaporation does not carry away solids in the water such as mud, silt, or dissolved solids;therefore, it is
39

316(b)Compliance Submittal
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necessary to continuously discharge some of the circulating water to remove waste and prevent a
buildup of solids in the circulating water. This discharge, called blowdown, is routed to the Lined
Retention Basin.
The cooling tower has five main components:
1. the blower type fans which direct the airflow upward,
2. the heat transfer section commonly called the "fill",
3. the water distribution system,
4. the drift eliminator section, and
5. the concrete basin which collects water for return to the condenser and other heat exchangers.
0 ,A\
mac IV,^ �x a..�,o.� ni g- Ic'. 1
itkiN 0014 1400i t o Wve. #i r ft, ice® r 4,14 t r
ut
p W 7.7.7i w,z _..ram u- utee sa .. �. •\.
e 7 .ao e
1. 1is
i l
a a )pppyl"futiel VIEW wa
Figure 5-1. Mayo Cooling Tower General Arrangement
5.1.2 Proportion of Design Flow Used in the Cooling Water System
Water withdrawals from Mayo Reservoir to support plant operations from 2016 through 2020 are
provided in Table 3-1(Section 3.4). Based on the engineering design water balance diagram (Figure 3-1),
approximately 95 percent of the MWIS withdrawal is used for makeup to the cooling tower. The
remainder is used as service water for various plant uses such as fire protection water, boiler wash
water, and boiler makeup water. Table 5-1 provides the proportion of the 26.64 MGD DIF withdrawn
during the 2016-2020 period.
Table 5-1. Percent Monthly Proportion of Design Flow Withdrawn at the Mayo MWIS.
Month 2016 2017 2018 2019 2020 Average
January 33.7 24.7 36.8 29.6 9.9 27.0
February 27.1 21.9 17.2 12.7 13.4 18.4
March 15.2 28.6 14.5 14.7 15.6 17.7
April 18.1 13.7 33.9 2.2 10.5 15.7
May 28.0 15.8 34.1 23.9 10.3 22.4
June 39.3 42.3 46.3 42.5 26.8 39.5
July 43.6 58.7 45.5 40.6 35.1 44.7
August 44.2 58.0 44.9 35.8 36.5 43.9
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316(b)Compliance Submittal
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Month 2016 2017 2018 2019 2020 Average
September 47.1 21.3 29.8 50.2 15.7 32.8
October 23.7 26.8 4.6 26.9 8.1 18.0
November 28.1 12.1 6.4 25.9 8.1 16.1
December 24.3 33.8 42.6 20.3 10.4 26.3
Although historical averages are not necessarily indicative of future withdrawals, only 26.9 percent of
the DIF was withdrawn from Mayo Reservoir from 2016 through 2020.
5.1.3 Cooling Water System Operation Characterization
Operation of the cooling water system results in an increased makeup water demand and makeup water
pump operation. As presented in Section 3.3,the MWIS operated nearly continuously during the 2016-
2020 period. Steam turbine typically occur in the spring and/or fall.
Monthly total flow data during the 2016-2020 period are provided n Figure 5-2. MWIS withdrawals
during the summer months (i.e., May to September) are typically higher than the remainder of the year
due to increased cooling tower evaporation, higher electrical generation load, and higher ambient
temperatures.
500
450
400
350
c 300
0
E 250 .�
(.7 200 , -.
150 _.- _
50 a, j
_ ' _ . I
0
�Ja� c�a�� a�� P �aJ �J�e �J QoJ�� ��c o�� sec sec
cep � �e�e pe` �oatc aece'
■2016 ■ 2017 ■2018 2019 ■ 2020
Figure 5-2. Monthly Total MWIS Withdrawals at Mayo
At normal Mayo Reservoir pool elevation,the calculated TSV is 0.28 fps at the DIF(18,500 gpm) and the
calculated TSV is 0.07 fps at the AIF (4,972 gpm)fps. Both of these values are considerably less than the
0.5 fps alternative in the 316(b) Rule for impingement compliance. Appendix C provides TSV
calculations.
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316(b) Compliance Submittal
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5.1.4 Distribution of Water Reuse
The distribution of water reuse does not apply to Mayo because this facility does not reuse cooling
water as process water, reuse process water for cooling purposes, or use grey water for cooling
purposes.
5.1.5 Description of Reductions in Total Water Withdrawals
The 2016-2020 average water withdrawal is reduced by 73.1 percent as compared to the design flow.
Note that the design flow is based on only one of the two installed cooling tower makeup pumps. The
average flow reduction is substantial when compared to the DIF.
5.1.6 Description of Cooling Water Used in Manufacturing Process
Mayo makeup cooling water is not used in a manufacturing process either before or after the water is
used for cooling.
5.1.7 Proportion of Source Waterbody Withdrawn
Withdrawal from the Mayo Reservoir is dependent on the cooling tower makeup water demand,
maximum pump capacity, and water losses due to evaporation and system losses. The daily average
percent withdrawal of Mayo Reservoir(assuming full pool) during the 2016-2020 period are provided in
Table 5-3. The percent of source water withdrawal ranges from a low of<0.01 percent (October 2018
and April 2019) to a high of 0.06 percent (July and August 2017).
Table 5-2. Mayo MWIS Percent of Source Waterbody(Mayo Reservoir)Withdrawal
Month 2016 2017 2018 2019 2020
January 0.03 0.02 0.04 0.03 0.01
February 0.03 0.02 0.02 0.01 0.01
March 0.01 0.03 0.01 0.01 0.02
April 0.02 0.01 0.03 <0.01 0.01
May 0.03 0.02 0.03 0.02 0.01
June 0.04 0.04 0.01 0.04 0.03
--
July _ 0.04 0.06 0.01 0.04 0.03
August 0.04 0.06 0.04 0.03 0.04
September 0.05 0.02 0.03 0.05 0.02
October 0.02 0.03 <0.01 0.03 0.01
November 0.03 0.01 0.01 0.02 0.01
December 0.02 0.03 0.04 0.02 0.01
Annual 0.03 0.03 0.03 0.03 0.02
Average
During the 2016-2020 period of record for this report,the Mayo average withdrawal was 0.03 percent of
the Mayo Reservoir source waterbody.
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316(b)Compliance Submittal
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5.2 Design and Engineering Calculations [§122.21(r)(5)(ii)]
The following table provides calculated TSV values. Appendix C presents the engineering calculations of
TSV for the traveling screen design as prepared by a qualified professional.
Table 5-3.MWIS TSV Calculations at Mayo Reservoir Pool Elevation.
Flow Scenario Calculated TSV
AIF (2016-2020) 0.07 fps
DIF (one pumps) 0.28 fps
5.3 Description of Existing Impingement and Entrainment
Reduction Measures [§122.21(r)(5)(iii)]
Mayo achieves substantial reductions in entrainment and impingement by means of flow reduction.The
underlying assumption for entrainment is that entrainable organisms have limited or no motility and
passively move with the water entering the power plant;therefore, reduction in flow results in a
commensurate reduction in entrainment.This flow reduction is achieved through the use of mechanical
draft wet cooling towers. Utilization of closed-cycle cooling results in a flow reduction of 98.1 percent
relative to OTC at Mayo.
In addition to providing a significant reduction of organisms entrained,the lower flows associated with
closed-cycle cooling also result in a commensurate reduction in the potential for impingement at the
facility. As the MWIS traveling screens have a maximum TSV of 0.28 fps at the DIF and Mayo Reservoir
pool elevation,the risk of impingement is essentially eliminated. The annual average AIF of 7.16 MGD at
Mayo(see Section 3.4) is low, as well as the calculated TSV of 0.07 fps. Thus,the MWIS AOI would not
extend beyond the face of the screens and is substantially less than the source waterbody current.
Based on the AOl calculations and site conditions, impingement at Mayo is expected to be negligible.
5.3.1 Best Technology Available for Entrainment
To aid the Director in making a BTA determination,the following information is provided to support the
conclusion that the existing Mayo MWIS configuration and operation results in the maximum reduction
in entrainment and no additional entrainment controls are warranted.
Most importantly, Mayo uses closed-cycle cooling,which minimizes entrainment through flow
reduction. The flow reduction achieved, compared to OTC, is calculated at 98.1 percent. The EPA allows
broad flexibility in the BTA determination for individual facilities, but also supports closed-cycle cooling
as a BTA option for entrainment as confirmed through this statement in the preamble to the Rule:
"Although this rule leaves the BTA entrainment determination to the Director,with the
possible BTA decisions ranging from no additional controls to closed-cycle recirculating
systems plus additional controls as warranted, EPA expects that the Director, in the site-
specific permitting proceeding,will determine that facilities with properly operated
closed-cycle recirculating systems do not require additional entrainment reduction
control measures."
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316(b)Compliance Submittal
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Closed-cycle cooling as a potential entrainment BTA is further reiterated in the Response to Public
Comments document,where EPA states:
"EPA has made it clear that a facility that uses a closed-cycle recirculating system, as
defined in the rule, would meet the rule requirements for impingement mortality at§
125.94(c)(1).This rule language specifically identifies closed-cycle as a compliance
alternative for the [impingement mortality] performance standards. EPA expects the
Director would conclude that such a facility would not be subject to additional
entrainment controls to meet BTA."
The final rule for new facilities as well as the new units provision within the Rule provide similar support
for closed-cycle cooling as entrainment BTA at Mayo:
• The final Rule for new facilities published in the Federal Register on December 18, 2001 and
with an effective date of January 17, 2002 does prescribe BTA for entrainment,which Mayo
meets. Regulations are more stringent for new facilities than for existing facilities. By virtue of
meeting the most stringent entrainment BTA criteria (i.e.,applicable to new facilities), Mayo is
compliant for entrainment BTA under the final Rule for existing facilities.
• If Mayo were classified as a new unit at an existing facility,the station would be in compliance
with the more stringent requirements stated at§125.94(e), BTA standards for impingement
mortality and entrainment for new units at existing facilities.
Beyond this regulatory guidance,the number of organisms expected to be entrained at Mayo is very
low. Since entrainment is proportional to flow, reductions in flow equate to commensurate reductions
in entrainment. The use of closed-cycle cooling as compared to an equivalent OTC facility is estimated
to reduce entrainment by 98.1 percent.
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6 Chosen Method(s) of Compliance with
Impingement Mortality Standard [§122.21(r)(6)]
The information required to be submitted per 40 CFR§ 122.21(r)(6) is as follows:
The owner or operator of the facility must identify the chosen compliance method for the
entire facility;alternatively, the applicant must identify the chosen compliance method
for each cooling water intake structure at its facility. The applicant must identify any
intake structure for which a BTA determination for Impingement Mortality under 40 CFR
125.94(c)(11)or(12)is requested.
The Rule at 40 CFR 125.94(c) provides existing facilities with seven BTA options for achieving
impingement mortality compliance. A facility needs to implement only one of these options to comply
with the Impingement Mortality Standard. Highlighted text indicates the compliance option for Mayo.
1. Operate a closed-cycle recirculating system as defined at 40 CFR 125.92(c)(1) (this includes wet,
dry or hybrid cooling towers,a system of impoundments that are not WOTUS, or any
combination thereof);
2. Operate a cooling water intake structure that has a maximum design through-screen velocity of
0.5 fps or less;
3. Operate a cooling water intake structure that has a maximum actual through-screen velocity of
0.5 fps or less;
4. Operate an existing offshore velocity cap that is a minimum of 800 feet offshore and has bar
screens or otherwise excludes marine mammals, sea turtles, and other large aquatic organisms;
5. Operate a modified traveling screen system such as modified Ristroph screens with a fish
handling and return system, dual flow screens with smooth mesh, or rotary screens with fish
returns. Demonstrate that the technology is or will be optimized to minimize impingement
mortality of all non-fragile species;
6. Operate any combination of technologies, management practices, and operational measures
that the Director determines is BTA for reducing impingement. As appropriate to the system of
protective measures implemented, demonstrate the system of technologies has been optimized
to minimize impingement mortality of all non-fragile species; and
7. Achieve a 12-month performance standard of no more than 24 percent mortality including
latent mortality for all non-fragile species.
Compliance options 1, 2, and 4 are essentially pre-approved technologies that require minimal
additional monitoring after their installation and proper operation. Options 3, 5, and 6 require that
more detailed information be submitted to the Director before they can be specified as the BTA to
reduce impingement mortality. Options 5, 6, and 7 require demonstrations with field studies that the
technologies have been optimized to minimize impingement mortality of non-fragile species.
45

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In addition,the Rule provides two other impingement compliance BTA options for which the Director
may consider little or no additional controls for impingement mortality(USEPA 2014a). These options
apply under very specific circumstances.
• De minimis rate of impingement—if the rates of impingement at a facility are so low that
additional impingement controls may not be justified (Section 125.94(c)(11)); and
• Low Capacity utilization of generating units—if the annual average capacity utilization rate of a
24-month contiguous period is less than 8 percent (Section 125.94(c)(12)).
Mayo meets the requirements of 40 CFR§125.94(c)(1) (BTA Option#1) based on data provided in Table
5-2. In addition,the MWIS has a design and actual low through-screen velocity.
By meeting the CCRS criterion (BTA#1)the existing technologies in use at Mayo are BTA for
impingement mortality compliance.
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7 Entrainment Performance Studies [§ 122.21(r)(7)]
The information required to be submitted per 40 CFR§ 122.21(r)(7), Entrainment performance studies,
is as follows:
The owner or operator of an existing facility must submit any previously conducted
studies or studies obtained from other facilities addressing technology efficacy, through-
facility entrainment survival, and other entrainment studies.Any such submittals must
include a description of each study, together with underlying data, and a summary of
any conclusions or results.Any studies conducted at other locations must include an
explanation as to why the data from other locations are relevant and representative of
conditions at your facility. In the case of studies more than 10 years old, the applicant
must explain why the data are still relevant and representative of conditions at the
facility and explain how the data should be interpreted using the definition of
entrainment at 40 CFR 125.92(h).
7.1 Site-Specific Studies
Mayo utilizes a CCRS,therefore adverse entrainment impacts are not anticipated. Hence, no site-
specific entrainment performance studies (such as studies evaluating biological efficacy of specific
entrainment reducing technologies or through-facility entrainment survival) have been conducted for at
Mayo.
Section 4 of this report provides a discussion of the fish community monitoring conducted within the
MWIS source waterbody(Mayo Reservoir).
7.2 Studies Conducted at Other Locations
As of the date of this report, no entrainment performance studies conducted at other facilities have
been determined relevant for documentation in this section.
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8 Operational Status [§ 122.21(r)(8)]
The information required to be submitted per 40 CFR§122.21(r)(8), Operational status, is outlined as
follows:
(i) For power production or steam generation, descriptions of individual unit operating
status including age of each unit, capacity utilization rate (or equivalent)for the
previous 5 years, including any extended or unusual outages that significantly affect
current data for flow, impingement, entrainment, or other factors, including
identification of any operating unit with a capacity utilization rate of less than 8 percent
averaged over a 24-month block contiguous period, and any major upgrades completed
within the last 15 years, including but not limited to boiler replacement, condenser
replacement,turbine replacement, or changes to fuel type;
(ii) Descriptions of completed, approved, or scheduled uprates and Nuclear Regulatory
Commission relicensing status of each unit at nuclear facilities;
(iii) For process units at your facility that use cooling water other than for power production
or steam generation, if you intend to use reductions in flow or changes in operations to
meet the requirements of 40 CFR 125.94(c),descriptions of individual production
processes and product lines, operating status including age of each line, seasonal
operation, including any extended or unusual outages that significantly affect current
data for flow, impingement, entrainment, or other factors, any major upgrades
completed within the last 15 years, and plans or schedules for decommissioning or
replacement of process units or production processes and product lines;
(iv) For all manufacturing facilities, descriptions of current and future production schedules;
and,
(v) Descriptions of plans or schedules for any new units planned within the next 5 years.
Each of these requirements is described in the following subsections.
8.1 Description of Operating Status [§ 122.21(r)(8)(i)]
Mayo operates as needed to provide electrical generation for customer use. Plant outages typically
occur during the spring(February to May) and/or in the fall/winter(October to December) months.
8.1.1 Individual Unit Age
The existing Mayo unit began commercial operations during March 1983. Therefore at the time of this
report the Mayo unit has nearly 39 years of commercial operations.
8.1.2 Utilization for Previous Five Years
Monthly and annual average capacity factor information for 2016-2020 is provided in Table 8-1. Annual
capacity factors during this period ranged from 10.0 to 31.2 percent.
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Table 8-1. Mayo Unit 1 Annual Capacity Factors,2016-2020.
Month 2016 2017 2018 2019 2020
January 33.3 22.3 52.7 33.4 0
February 26.3 19.2 12.4 6.5 2.5
March 6.6 34.1 12.8 11.9 10.3
April 8.0 11.3 35.4 0 0
May 26.5 5.2 26.5 33.1 0
June 38.3 31.1 37.3 42.1 24.7
- -- --- -------------------
July 59.5 47.7 26.6 32.4 37.4
August 58.7 45.7 23.5 26.5 40.5
September 54.0 5.4 9.2 56.4 4.9
October 14.2 7.3 0 11.3 0
November 31.1 0 0 3.3 0
December 17.9 32.0 37.2 22.7 0
Annual Average 31.2 21.8 22.8 23.3 10.0
Note:Annual average may not equal monthly total average due to rounding.
8.1.3 Major Upgrades in Last Fifteen Years
Mayo commissioned a flue gas desulphurization (FGD)during 2009, installed a wastewater thermal
evaporator system during 2015, installed a pneumatic bottom ash system during 2013, completed
wastewater management revisions in 2019, and is in the process of performing ash pond closure
activities.
8.2 Description of Consultation with Nuclear Regulatory
Commission [§122.21(r)(8)(ii)]
Mayo does not have a nuclear fueled unit;therefore,this subsection is not applicable.
8.3 Other Cooling Water Uses for Process Units [§122.21(r)(8)(iii)]
Mayo is not a manufacturing facility;therefore,this subsection is not applicable.
8.4 Description of Current and Future Production Schedules
[§122.21(r)(8)(iv)]
Mayo is not a manufacturing facility;therefore,this subsection is not applicable.
8.5 Description of Plans or Schedules for New Units Planned within
Five Years [§122.21(r)(8)(v)]
During the next five years,there are no current plans to decommission, replace, or add new units at this
facility as stated in the 2020 Integrated Resource Plan.
The retirement date of the existing Mayo unit is somewhat uncertain at this time. According to the
2020 Duke Energy Sustainability Report(Duke 2021),the existing Mayo unit is to retire in 2028. I
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However, recent North Carolina legislation (HB951)9 or other operational requirements may result in
changes to the 2028 retirement projection.
9 North Carolina HB951(HB951,2020)requires the North Carolina Utility Commission (NCUC)to take all
reasonable efforts to achieve a 70%reduction in CO2 emissions by 2030 for the electric public utility sector(as
referenced to a 2005 baseline) in an"affordable, reliable manner". HB951 also requires net zero CO2 emissions
by 2050. The NCUC is to develop the initial plan by December 31,2022 and to update this plan every two years
thereafter.
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9 References
Bailey, R.M.A systematic revision of the centrarchid fishes,with a discussion of their distribution,
variation, and probable interrelationships. Doctoral dissertation, University of Michigan,Ann
Arbor.Becker, G. C. 1983. Fishes of Wisconsin. University of Wisconsin Press, Madison WI.
Beckman, W.C. 1952. Guide to the fishes of Colorado. University of Colorado Museum, Boulder.
Bigelow, H.B. and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. U.S. Fish and Wildlife service
Fisheries Bulletin 53. (Reprinted 1964, Museum of Comparative Zoology, Harvard University,
Cambridge, Massachusetts.)
Bodola,A. 1966. Life History of the Gizzard Shad, Dorsoma cepdianum (Lesuer), in western Lake Erie.
U.S. Fish and Wildlife Service Fisheries Bulletin 65:391-425.
Carlander, K.D. 1977. Handbook of Freshwater Fishery Biology.Vol. 2.The Iowa State University Press,
Ames IA. 431 pp.
Coggeshall, L.T. 1924.A study of the productivity and breading habits of the Bluegill, Lepomis pallidus
(Mitch.). Proceedings of Indiana Academy of Science 33:315-320.
Crowe,W. R. 1959.The Bluegill in Michigan. Michigan Department of Conservation Fish Division
Pamphlet 31.
Duke 2021. 2020 Duke Energy Sustainability Report. Duke Energy Corporation. Charlotte NC.
DEP 2016. Mayo Steam Electric Plant 2015 annual environmental monitoring report. Duke Energy
Progress, LLC. Raleigh NC.
DEP 2017. Mayo Steam Electric Plant 2016 annual environmental monitoring report. Duke Energy
Progress, LLC. Raleigh NC.
DEP 2018. Mayo Steam Electric Plant 2017 annual environmental monitoring report. Duke Energy
Progress, LLC. Raleigh NC.
DEP 2019. Mayo Steam Electric Plant 2018 annual environmental monitoring report. Duke Energy
Progress, LLC. Raleigh NC.
DEP 2020. Mayo Steam Electric Plant 2019 annual environmental monitoring report. Duke Energy
Progress, LLC. Raleigh NC.
Ehrlich, K. F. 1974. Chemical changes during growth and starvation of herring larvae. Pages 301-323 in J.
H. S. Blaxter, editor. The early life history of fish. Springer-Verlag, New York.
Gebhart, Glen E., and Robert C. Summerfelt. 1978. Seasonal Growth of Fishes in Relation to Conditions
of Lake Stratification. Oklahoma Cooperative Fishery Research Unit 58 (1978): 6-10. Oklahoma
State University, Stillwater OK.
Gerald,J. W. 1971. Sound production during courtship in six species of sunfish (Centrarchidae). Evolution
25:75-87.
51

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Graham,J. H., and Hastings, R.W. 1984. Distributional patterns of sunfishes on the New Jersey Coastal
Plain. Environmental Biology of Fishes 10:137-148.
Griffith, G.E., Omemik,J.M., Comstock, M.P.,Schafale,W.H., McNab, D.R., Lenat, D.R., and MacPherson,
T.F. 2002. Ecoregions of North Carolina. U.S. Environmental Protection Agency, Corvallis OR.
(map scale 1:1,500,000).
Gross, M. R., and MacMillan,A. M. 1981. Predation and the evolution of colonial nesting in Bluegill
sunfish (Lepomis macrochirus). Behavioral Ecology and Sociobiology 8:167-174.
Guillory,V. 1979. Life history of Chain Pickerel in a central Florida lake. Florida Game and Fresh Water
Fish Commission, Fishery Bulletin 8,Tallahassee.
Guillory,V. 1984. Reproductive biology of Chain Pickerel in Lake Conway, Florida. Proceedings of the
Annual Conference Southeastern Association of Fishes and Wildlife Agencies 35(1981):585-591.
Gunter,G.S. 1938. Seasonal variation in abundance of certain estuarine and marine fishes with
particular reference to life histories. Ecological Monographs 8:313-346.
Hildebrand,S.F., and W.C. Schroeder. 1928. Fishes of Chesapeake Bay. U.S. Bureau of Fisheries Bulletin
43. (Reprinted 1972 Tropical Fish Hobbyist Publications, Neptune City, New Jersey.)
Jenkins, R.E. and Burkhead, N.M.1994. Freshwater Fishes of Virginia.American Fisheries Society,
Bethesda MD.
Jenkins, R.E., and Burkhead, N.M. 1993. Freshwater Fishes of Virginia. American Fisheries Society,
Bethesda MD.
Jenkins, R. E. 1970.Systematic studies of the catostomid fish tribe Moxostomitini. Doctoral dissertation.
Cornell University, Ithaca NY.
Jones, P.W., F.D. Martin, and J.D. Hardy. 1978. Development of fishes of the Mid-Atlantic Bight. An atlas
of egg, larval and juvenile stages,Volume 1. U.S. Fish and Wildlife Service Biological Services
Program FWS-OBS-78/12.
Kendall,W.C. 1917.The pikes:their geographical distribution habits, culture,and commercial
importance. U.S. Commissioners Fisheries Report for 1917. Bureau of Fisheries Document 853.
45 pp.
Kunz,A., and L Radcliffe. 1917. Notes on the embryology and development of twelve species of
teleostean fishes. U.S. Bureau of Fisheries Bulletin 15:87-134.
Lippson,A.J., and R.L. Moran, editors. 1974. Manual for identification of early developmental stages of
fishes of the Potomac River estuary. Maryland Department of Natural Resources, Power Plant
Siting Program, Miscellaneous Publications 13,Annapolis.
Loar,J.M, Griffith,J.S., and Kumar, K.D. 1978. An analysis of factors influencing the impingement of
threadfin shad at power plants in the southeastern United States. Pages 245-255 in L.C.Jensen,
editor. Fourth national workshop on entrainment and impingement. EA Communications,
Melville NY.
52

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Loesch,J.G., and W.A. Lund. 1977. A contribution to the life history of the Buleback herring,Alosa
aestivalis.Transactions of the American Fisheries Society 106: 583-589.
May, R.C. 1974 Larval mortality in marine fishes and the critical period concept. Pages 3-19 in J. H.S.
Blaxter, editor. The early life history of fish. Springer-Verlag, New York.
Menhinick, E.F. 1993. The Freshwater Fishes of North Carolina. North Carolina Wildlife Resources
Commission, Raleigh, NC.
Meyer, W. H. 1962. Life history of three species of redhorse (Moxostoma) in the Des Moines River, Iowa.
Transactions of the American Fisheries Society 91:412-419.
Miller, R.R. 1960.Systematic and biology of the Gizzard Shad (Dorosoma cepedianum) and related
Fishes. U.S. Fish and WildlifeBulletin
Service ce Fishery r s e y Bu letin 60(173):370-392.
Miller, R.R. 1964. Genus Dorosoma Rafinesque 1820. Gizzard Shads,Threadfin Shads. Pages 443-451 in
Fishes of the western North Atlantic Part 3. Sears Foundation for Marine Research. Yale
University, New Haven, Connecticut.
Miller,T.J.,Crowder, L.B., Rice,J.A., Marshall, E.A. 1988. Larval size and recruitment mechanisms in
fishes:toward a conceptual framework. Canadian Journal of Fisheries and Aquatic Sciences
45:1657-1670 p.
Musick,J. A. 1972. Fishes of Chesapeake Bay and the adjacent Coastal Plain. Pages 175-212 in M. L.
Wass editor. A check list of bota of lower Chesapeake Bay. Virginia Institute of Marine Science
Special Scientific Report 65.
North Carolina Department of Environmental Quality (NCDEQ) 2018. Roanoke River Basin Restoration
Priorities October 2009 Amended August 2018. Accessed February 27, 2020.
https://files.nc.gov/ncdeq/Mitigation%20Services/Watershed Planning/Roanoke River Basin
/Roanoke-RB R P-082018.pdf
NCDEQ 2021. Division of Water Resources Water Classification map. Accessed February 10, 2021.
https://ncdenr.maps.arcgis.com/apes/webappviewer/index.html
North Carolina Department of Natural and Cultural Resources (NCDNCR). 2021. North Carolina Natural
Heritage Data Explorer element occurrence data. NCDNCR, Raleigh NC.
https://deq.nc.gov/about/divisions/water-resources/planning/basin-planning/water-resource-
plans/roanoke-2006
NCDWR 2014. Lake and reservoir assessments Roanoke River basin. Division of Water Quality. Water
Sciences Section, Raleigh NC.
North Carolina General Assembly(HB951). Energy Solutions for North Carolina. House Bill 951/SL
2021-165. Accessed January 20, 2022. https://www.ncleg.gov/BillLookup/2021/H951
Robbins,W. H., and H. R. MacCrimmon. 1974.The blackbass in America and overseas. Biomanagement
Research Enterprises,Sault Ste. Marie, Ontario.
Rohde, F. C.,Arndt,J. W., Foltz, and Quattro,J. W. 2009. Freshwater Fishes of South Carolina. University
of South Carolina Press, Columbia SC.430 pp.
53

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Schneider, R.W. 1969. Some aspects of the life history of the Gizzard Shad, Dorsoma cepdianum in Smith
Mountain Lake,Virginia. Master's thesis.Virginia Polytechnic Institute and State University,
Blacksburg.
Scott,W.B. and E.J. Crossman. 1973. Freshwater fishes of Canada. Fisheries Research Board of Canada
Bulletin 184.
Shelton,W.L. and B. G. Grinstead. 1973. Hybridization between Dorsoma cepedianum and D. petenense
in Lake Texoma,Oklahoma. Proceedings of the Annual Conference Southeastern Association of
Game and Fish Commissioners 26(1972):506-510.
Trautman, M. B. 1981. Fishes of Ohio with illustrated keys, revised edition. Ohio State University Press,
Columbus OH.
United States Army Corps of Engineers (USACE). 1978. Mayo Electric Generating Plant Final
Environmental Statement.
United States Environmental Protection Agency (USEPA). 2001. National Pollutant Discharge Elimination
System: Regulations Addressing Cooling Water Intake Structures for New Facilities: Final Rule.
40 CFR Parts 9 and 122, et al. Federal Register Vol.66 No. 243. December 18, 2001.
United States Environmental Protection Agency(USEPA). 2014. National Pollutant Discharge Elimination
System - Final Regulations to Establish Requirements for Cooling Water Intake Structures at
Existing Facilities and Amend Requirement at Phase I Facilities; Final Rule. 40 CFR Parts 122 and
125. Federal Register Vol. 79 No. 158.August 15, 2014.
United States Fish and Wildlife Service (USFWS). 1987, 1988, 2017. Environmental Conservation Online
System (ECOS). Accessed May 3, 2021.
https://ecos.fws.gov/ecp/species/1134#conservationPlans.
USGS. 2012. U.S. Geological Survey,StreamStats Program Ver.4.3.0,site visited 4/2/19 at
http://streamstats.usgs.gov.
United States Geologic Survey(USGS) 2020. Nonindigenous Aquatic Species (NAS).
https://nas.er.usgs.gov/queries/SpeciesList.aspx?Group=Fishes. Accessed February 10, 2020.
USFWS(United States Fish and Wildlife Service). 2020. Information for Planning and Consulting(IPaC).
https://ecos.fws.gov/ipac/ accessed February 10, 2020.
Wang,J.C.S., and R.J. Kernehan. 1979. Fishes of the Delaware estuaries:a guide to the early life
histories. E A Communications, Ecological Analysts,Townson, Maryland.
Wilbur, R.L. 1969.The Redear Sunfish in Florida. Florida Game and Fresh Water Fish Commission, Fishery
Bulletin 5,Tallahassee.
Whitehurst, D.K. Personal communication. Cited in,Jenkins, R.E., and N.M. Burkhead. 1993. Freshwater
Fishes of Virginia. American Fisheries Society, Bethesda, Maryland.
54

316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Appendices

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Appendix A. Mayo Plant §122.21(r)(2) — (8) Submittal
Requirement Checklist.
(2)(i) Narrative description and scaled drawings of source Yes
waterbody.
a (2)(ii) Identification and characterization of the source Yes
Ywaterbody's hydrological and geomorphological
RS
3 o features, as well as the methods used to conduct any
°' physical studies to determine intake's area of
influence within the waterbody and the results of
such studies.
^' (2)(iii) Locational maps. Yes
4, (3)(i) Narrative description of the configuration of each Yes
(13
CWIS and where it is located in the waterbody and in
the water column.
c (3)(ii) Latitude and Longitude of CWIS. Yes
o v, (3)(iii) Narrative description of the operation of each CWIS. Yes
`' Y (3)(iv) Flow distribution and water balance diagram. Yes
01 CO
�" (3)(v) Engineering drawing of CWIS. Yes
(4)(i) A list of the data supplied in paragraphs (r)(4)(ii) Yes, but not
coo through (vi) of this section that are not available and applicable
o efforts made to identify sources of the data. because all data
is available.
(4)(ii) A list of species (or relevant taxa)for all life stages and Yes
ca
•� their relative abundance in the vicinity of CWIS.
m (4)(iii) Identification of the species and life stages that would Yes
t be most susceptible to impingement and entrainment.
70 (4)(iv) Identification and evaluation of the primary period of Yes
oa reproduction, larval recruitment, and period of peak
abundance for relevant taxa.
(4)(v) Data representative of the seasonal and daily Yes
= activities of biological organisms in the vicinity of
CWIS.
m (4)(vi) Identification of all threatened, endangered, and Yes
other protected species that might be susceptible to
impingement and entrainment at cooling water intake
structures.
(4)(vii) Documentation of any public participation or Yes, but not
consultation with Federal or State agencies applicable.
C7 undertaken in development of the plan.
A-1

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
(4)(viii) Methods and QA procedures for any field efforts. Yes, but not
applicable as no
new data have
been collected.
(4)(ix) In the case of the owner or operator of an existing Yes, noted in
facility or new unit at an existing facility,the Source report that (i)
Water Baseline Biological Characterization Data is the through (xii)
information included in (i)through (xii). provide this
information.
(4)(x) Identification of protective measures and stabilization Yes
activities that have been implemented, and a
description of how these measures and activities
affected the baseline water condition in the vicinity of
CWIS.
(4)(xi) List of fragile species as defined at 40 CFR 125.92(m) Yes
at the facility.
(4)(xii) Information submitted to obtain Incidental take Yes, but not
exemption or authorization for its cooling water applicable.
intake structure(s)from the U.S. Fish and Wildlife
Service or the National Marine Fisheries Service.
(5)(i) Narrative description of the operation of the cooling Yes
water system and its relationship to CWIS.
(5)(i) Number of days of the year the cooling water system Yes
is in operation and seasonal changes in the operation
of the system.
co
(5)(i) Proportion of the design intake flow that is used in the Yes
o system.
(5)(i) Proportion of design intake flow for contact cooling, Yes
a non-contact cooling, and process uses.tA
(5)(i) Distribution of water reuse to include cooling water not applicable
cu
reused as process water, process water reused for
CO
cooling, and the use of gray water for cooling.
(5)(i) Description of reductions in total water withdrawals Yes
c including cooling water intake flow reductions already
achieved through minimized process water
withdrawals.
(5)(i) Description of any cooling water that is used in a not applicable
manufacturing process either before or after it is used
for cooling, including other recycled process water
flows.
(5)(i) Proportion of the source waterbody withdrawn (on a Yes
monthly basis).
A-2

316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
(5)(ii) Design and engineering calculations prepared by a Yes
qualified professional and supporting data to support
the description required by paragraph (r)(5)(i) of this
section.
(5)(iii) Description of existing impingement and entrainment Yes
technologies or operational measures and a summary
of their performance.
Identification of the chosen compliance method for the entire Yes
CWIS or each CWIS at its facility.
(6)(i) Impingement Technology Performance Optimization No, not selected
Study for Modified Travelling Screen. compliance path
s Two years of biological data collection. and thus not
applicable.
a)
u ea
C -O
c
O .2
E
O
U
o r Demonstration of Operation that has been optimized
2 to minimize impingement mortality.
tc Complete description of the modified traveling
• cuscreens and associated equipment.
2 a (6)(ii) Impingement Technology Performance Optimization
VI• Q Study for Systems of Technologies as BTA for
r E Impingement Mortality.
Minimum of two years of biological data measuring
the reduction in impingement mortality achieved by
the system.
(7)(i) Site-specific studies addressing technology efficacy, Yes; note that no
through plant entrainment survival, and other site-specific
impingement and entrainment mortality studies. studies were
E conducted at this
,o facility.
a a, (7)(ii) Studies conducted at other locations including an Yes; note that
✓ explanation of how they relevant and representative. studies at other
E v, locations were
co not determined
to be relevant.
(7)(iii) Studies older than 10 years must include an not applicable
explanation of why the data are still relevant and
representative.
i 3 (8)(i) Description of individual unit age, utilization for Yes
00 Q. o ;° previous 5 year, major upgrades in last 15 years.
O •— in
A-3

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
(8)(ii) Descriptions of completed, approved, or scheduled Yes, but not
uprates and Nuclear Regulatory Commission applicable.
relicensing status of each unit at nuclear facilities.
(8)(iii) Other cooling water uses and plans or schedules for Yes, but not
decommissioning or replacing units. applicable.
(8)(iv) For all manufacturing facilities, descriptions of current Yes, but not
and future production schedules. applicable.
(8)(v) Descriptions of plans or schedules for any new units Yes
planned within the next 5 years.
A-4

316(b) Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
Appendix B. Engineering Drawings of Cooling Water
Intake Structure
• Drawing S-2300: Cooling Tower Make Up Water Intake Structure Plan Sheet
1
• Drawing S-2302: Cooling Tower Make Up Water Intake Structure Plan &
Sections Sheet 3
• Drawing CH1381-101: General Arrangement Traveling Water Screen
B-1

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
_AMMAR'Of IS/M•ea0 o 00-TICS
_ .,e..
fflo
z ”--_ — �_-
�a _
NM
._.
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a! 1 —I ,y.��E�� 1Y-
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4— 1 -}"') 1-:�7IL " ' iin11� 0 _
2.76:,,. -v = '_ 6 i.3 it d spa =or--t,PIPE o°Me■
il ,e� ".— pig- Fps § - . — 1
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.eon soma. s.eeaic t•)i s "'J_ •
'
OP£RArws am:,PL<N_.a 6.l59 rs•C
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,.K:. v:.�,,,, .a.r..:wry l6 ':��w�7J'L. L = !• �� -- 4 Ti U425 00
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�+ K' -TOT)
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B-2

316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
r — me.--", -�, .... ^.a � �a / i1 Ur�'... „®' ++w.�.,... r
■". Bar , 4atl i I u I .»Bssa
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pgpg gg g y
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B-3

l
316(b)Compliance Submittal
MAYO STEAM ELECTRIC GENERATING PLANT
a.-�5C
Alf.1\ 1:14 tilia! 1111WITO .5...... '""*.\ : Z w/....I
/9114111 PM Oa ouR ' —' .14%
P11. 1.....•••
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dam''" I •
zy1 1 1 i --�s _-� .....=°_OM NW NMI�_Mal NPR
ff 1MGM
B-4

Appendix C. Engineering Calculations for Through-
Screen Velocity
c-i

MAYO Traveling Screen Through Screen Velocity(TSV)Calculations
Design Data
Mike Smallwood Pumping Capacity
11/16/2021 Nameplate= 18,500 gprn
2016-2020 Average= 4,972 grain
Gibbs&Hill Drawing 5-2302 lists lake levels
Evoqua replacement drawing(CH11381-101)indicates WIRE,3045S,WIRE MESH IS 814 GA(0.080 DIA.)W/3/8"SQUARE OPENINGS Water Depth Table
Screen basket width=6'10" Depth at MWIS invert=390.0 feet
Evoqua spec is 1.52 fps velocity(8'water depth,100%clean screen,and 18,500 gpm(
cau.w Condition Lake Level MWIS water depth
/a.........a A,rar•'rvacew... High 437.5 47.5
rrilaan a...
tla�-t- ♦• ro+Y .-T • Normal 434.0 440
y1e' . � iCtn..OW6 a.ew. Low 407.0 17.0 (note 1)
1 ALL 1*-' ' �� - k'!/ ?f "� PMP 446.0 56.0
—�'" I fl u� ''"'- ••.•'''''' 7 low-low 398.0 8.0 from Evoqua drawing)
_Mi'�:� -ram �re� , is � � - �I 1-level nMedm MAY-EAP-01-0006(rev9)that makeup
II '�` r a pumps lose suction.
`°�`.a'acr'La _Q I .w .ZT•4fai14:•:.a �i r�ae.aaa 2-fire water pumps lose suction at 393.0 as noted in
e°°.:a- ?s yyi'.rY+'if!.Lm= _ MAY EAP 01 0006(rev9).
3-an alternate pump(16,800 gpm)maybe used in the
e 4T 40111 if P spare intake bay after makeup pumps lose suction
___y ur.rer w.a> _ _ !!' tea! (elevation 407.0)Per MAY-EAP-0I-OW6(rev91.
n
!Y ■ 1 ■) di r e
a i 9■ ! � MI a
!.�rryn ih1iUh
Ill' 11I III w .
L':—.. •
ili
Ill3lgs-4'
SECr(QA/./.-./.
REPLACEMENT SCREEN DETAILS:(except as noted,all information from Evoqua replacement drawing CH11381-101(
126 feet of traveling screens
63 number of panels per traveling screen
2 feet height of each screen panel
6.833333 feet width of each screen panel
C-2

MAYO Traveling Screen Through Screen Velocity(TSV)Calculations
normal pool=407.0 feet,MWIS invert=390.0 feet
Mike Smallwood TSV= 0.23
11/16/2021 actual TSV= 0.28 (accounts for screen frame submerged in water column)
INSERT REQUESTED INFORMATION INTO GREEN CELLS AND SHEET CALCULATES TSV
Through-screen velocity calculated using Pankratz equation("Screening Equipment Handbook",1988)
V=Q/(WD•OA•TW•K) where V=velocity,feet/second
Q=flow rate,gallons/minute
WD=wetted screen depth,feet
OA=proportion of screen open area to total screen area=(mesh size*mesh size)/((mesh size+wire size)•(mesh size+wire size))
TW=screen basket width,feet
K=396 for through-flow screen and 740 for dual-flow screen
pump flow rate,gpm Evoqua drawing CHI1381-101
.., depth of screen in water column,ft Gibbs&Hill Drawing S-2302 and Evoqua drawing CHI1381-101
0.3 screen mesh opening,in Evoqua drawing CHI1381-101
0.3 screen mesh width,in same
0.3 screen mesh length,in same
screen mesh wire size,in same
screen basket width,ft same
number of screens for each pump same
enter 396 for through-flow screen or 740 for dual-flow screen
percent clogging
factor to account for screen frame
C-3

MAYO Traveling Screen Through Screen Velocity(TSV)Calculations
normal pool=407.0 feet,MWIS invert=390.0 feet
Mike Smallwood TSV= 0.06
11/16/2021 actual TSV= 0.07 (accounts for screen frame submerged in water column)
INSERT REQUESTED INFORMATION INTO GREEN CELLS AND SHEET CALCULATES TSV
Through-screen velocity calculated using Pankratz equation("Screening Equipment Handbook",1988)
V=Q/(WD•OA*TW*K) where V=velocity,feet/second
Q=flow rate,gallons/minute
WD=wetted screen depth,feet
OA=proportion of screen open area to total screen area=(mesh size•mesh size)/((mesh size+wire size)*(mesh size+wire size))
TW=screen basket width,feet
K=396 for through-flow screen and 740 for dual-flow screen
pump flow rate,gpm 2016-2020 water withdrawal data average
depth of screen in water column,ft Gibbs&Hill Drawing 5-2302 and Evoqua drawing CHI1381-101
screen mesh opening,in Evoqua drawing CHI1381-101 �•.„, ,.
screen mesh width,in same
screen mesh length,in same
screen mesh wire size,in same
screen basket width,ft same
number of screens for each pump same
enter 396 for through-flow screen or 740 for dual-flow screen
percent clogging
factor to account for screen frame
C-4

MAYO Traveling Screen Through Screen Velocity(TSV)Calculations
low pool=434.0 feet,M W IS invert=390.0 feet
Mike Smallwood TSV= 0.59
11/16/2021 actual TSV= 0.71 (accounts for screen frame submerged in water column)
INSERT REQUESTED INFORMATION INTO GREEN CELLS AND SHEET CALCULATES TSV
Through-screen velocity calculated using Pankratz equation("Screening Equipment Handbook",1988)
V=Q/(WD•OA•TW•K) where V=velocity,feet/second
Q=flow rate,gallons/minute
WD=wetted screen depth,feet
OA=proportion of screen open area to total screen area=(mesh size•mesh size)/((mesh size+wire size)*(mesh size+wire size))
TW=screen basket width,feet
K=396 for through-flow screen and 740 for dual-flow screen
pump flow rate,gpm Evoqua drawing CHI1381-101
depth of screen in water column,ft Gibbs&Hill Drawing S-2302 and Evoqua drawing CHI1381-101
D. screen mesh opening,in Evoqua drawing CHI1381-101 4
0 3 screen mesh width,in same
0.3 screen mesh length,in same
0.• screen mesh wire size,in same
6.' screen basket width,ft same
number of screens for each pump same
3 enter 396 for through-flow screen or 740 for dual-flow screen
percent clogging 411400031,0 sy ,.l
•
factor to account for screen frame
C-5

MAYO Traveling Screen Through Screen Velocity(TSV)Calculations
low pool=434.0 feet,M W IS invert=390.0 feet
Mike Smallwood TSV= 0.16
11/16/2021 actual TSV= 0.19 (accounts for screen frame submerged in water column)
INSERT REQUESTED INFORMATION INTO GREEN CELLS AND SHEET CALCULATES TSV
Through-screen velocity calculated using Pankratz equation("Screening Equipment Handbook",1988)
V=Q/(WD•OA•TW•K) where V=velocity,feet/second
Q=flow rate,gallons/minute
WD=wetted screen depth,feet
OA=proportion of screen open area to total screen area=(mesh size•mesh size)/((mesh size+wire size)•(mesh size+wire size))
TW=screen basket width,feet
K=396 for through-flow screen and 740 for dual-flow screen
pump flow rate,gpm 2016-2020 water withdrawal data average
depth of screen in water column,ft Gibbs&Hill Drawing 5-2302 and Evoqua drawing CHI1381-101
screen mesh opening,in Evoqua drawing CHI1381-101
screen mesh width,in same
screen mesh length,in same
screen mesh wire size,in same
screen basket width,ft same
number of screens for each pump same
enter 396 for through-flow screen or 740 for dual-flow screen
percent clogging citii4101WE:47 ,
factor to account for screen frame
C-6

MAYO Traveling Screen Through Screen Velocity(TSV)Calculations
low-low pool=398.0 feet,MWIS invert=390.0 feet
Mike Smallwood TSV= 1.26
11/16/2021 actual TSV= 1.52 (accounts for screen frame submerged in water column)
INSERT REQUESTED INFORMATION INTO GREEN CELLS AND SHEET CALCULATES TM/
Through-screen velocity calculated using Pankratz equation("Screening Equipment Handbook",1988)
V=Q/(WO•OA•TW•K) where V=velocity,feet/second
Q=flow rate,gallons/minute
WD=wetted screen depth,feet
OA=proportion of screen open area to total screen area=(mesh size•mesh size)/((mesh size+wire size)•(mesh size+wire size))
TW=screen basket width,feet
K=396 for through-flow screen and 740 for dual-flow screen
pump flow rate,gpm Evoqua drawing CHI1381-101
depth of screen in water column,ft Gibbs&Hill Drawing S-2302 and Evoqua drawing CHI1381-101
screen mesh opening,in Evoqua drawing CHI1381-101
screen mesh width,in same
screen mesh length,in same
screen mesh wire size,in same
screen basket width,ft same
number of screens for each pump same
enter 396 for through-flow screen or 740 for dual-flow screen
percent clogging
factor to account for screen frame
C-7

MAYO Traveling Screen Through Screen Velocity(TSV)Calculations
low-low pool=398.0 feet,MWIS invert=390.0 feet
Mike Smallwood TSV= 0.34
11/16/2021 actual TSV= 0.41 (accounts for screen frame submerged in water column)
INSERT REQUESTED INFORMATION INTO GREEN CELLS AND SHEET CALCULATES TSV
Through-screen velocity calculated using Pankratz equation("Screening Equipment Handbook",1988)
V=Q/(WD*OA'TW*K) where V=velocity,feet/second
Q=flow rate,gallons/minute
WD=wetted screen depth,feet
OA=proportion of screen open area to total screen area=(mesh size•mesh size)/((mesh size+wire size)*(mesh size+wire size))
TW=screen basket width,feet
K=396 for through-flow screen and 740 for dual-flow screen
pump flow rate,gpm 2016-2020 water withdrawal data average
depth of screen in water column,ft Gibbs&Hill Drawing 5-2302 and Evoqua drawing CHI1381 101
0 fig;screen mesh opening,in Evoqua drawing CHI1381-101 ***f `,
0 ;/.screen mesh width,in same
0 3 :screen mesh length,in same
0, screen mesh wire size,in same
6,, screen basket width,ft same
number of screens for each pump same
3'S enter 396 for through-flow screen or 740 for dual-flow screen
' percent clogging c i w;
12t factor to account for screen frame
C-8