NC0038377_WQ S18-005_20200423

tiN DUKE RECEIVED James Wells
ENERG�/ Vice President
Y Environmental,Health and Safety
MAY 01 2020 Programs 8 Environmental Sciences
526 South Church Street
Charlotte,NC 28202
NCDEQIDWRINPDES [phone]
April 23, 2020
Via Overnight Mail
Rick Bolich
Raleigh Regional Office Regional Supervisor
North Carolina Department of Environmental Quality
Division of Water Resources
1628 Mail Service Center
Raleigh, NC 27609
Bob Sledge
North Carolina Department of Environmental Quality
Division of Water Resources
Water Quality Permitting Program
1617 Mail Service Center
Raleigh, NC 27699-1617
Subject: Report Under Special Order by Consent—EMC SOC WQ S 18-005
Duke Energy Progress, LLC—Mayo Steam Electric Plant
NPDES Permit NC0038377
2019 Annual Seep Survey Report
Dear Messrs. Bolich and Sledge:
On behalf of Duke Energy Progress, LLC (DEP), I am submitting to you the Mayo Steam Electric
Plant Annual Seep Report summarizing the findings of the comprehensive survey as required by
Special Order by Consent (SOC), SOC No. S 18-005 Section 2.c.3).
As required by the SOC,I certify under penalty of law that this document and all attachments were
prepared under my direction or supervision in accordance with a system designed to assure that
qualified personnel properly gather and evaluate the information submitted. Based on my inquiry
of the person or persons who manage the system, or those persons directly responsible for
gathering the information, the information submitted is, to the best of my knowledge and belief,
true, accurate, and complete. I am aware that there are significant penalties for submitting false
information, including the possibility of fine and imprisonment for knowing violations.

Messrs. Bolich and Sledge
April 23, 2020
Page 2
Please direct any questions concerning the Mayo Steam Electric Plant SOC No. S 18-005 to Lori
Tollie at [phone] and to Chris Hallman at [phone] relative to the annual seep
inspection report.
Sincerely,
James W lls
Vice President, Environment, Health & Safety-
Programs and Environmental Sciences
Duke Energy
Attachment:
Mayo Steam Electric Plant 2019 Annual Seep Survey
CC: Richard Baker, Duke Energy
Lori Tollie, Duke Energy
Chris Hallman, Duke Energy
Leanne Wilson, Duke Energy
Paul Draovitch, Duke Energy
Matt Hanchey, Duke Energy

Terra
2019 ANNUAL SEEP REPORT
MAYO STEAM ELECTRIC PLANT
EMC SOC WQ S18-005
10660 BOSTON ROAD
RoxBORO, NC 27574
APRIL 2020
PREPARED FOR
taN DUKE
ENERGY
PP( (P cc
DUKE ENERGY PROGRESS, LLC
erry y ie, C G #1425
Senior Pro ct Manager

• 2019 Annual Seep Report April 2020
Mayo Steam Electric Plant, Duke Energy Progress, LLC SynTerra
TABLE OF CONTENTS
SECTION PAGE
1.0 INTRODUCTION 1-1
1.1 Inspection Details 1-1
2.0 FINDINGS 2-1
2.1 General Observations 2-1
2.2 Effects of Decanting 2-1
2.3 Changes to Seep Status 2-1
3.0 REFERENCES 3-1
LIST OF FIGURES
Figure 1 SOC Locations and Inspection Areas
LIST OF TABLES
Table 1 SOC Locations and Descriptions — 2019 Inspection
LIST OF APPENDICES
Appendix A Photographs
Page i

' 2019 Annual Seep Report April 2020
Mayo Steam Electric Plant,Duke Energy Progress,LLC SynTerra
LIST OF ACRONYMS
C&D Landfill Constructrion and Debris Landfill
EMC Environmental Management Commission
SOC Special Order by Consent
Page ii

• 2019 Annual Seep Report April 2020
Mayo Steam Electric Plant,Duke Energy Progress,LLC SynTerra
1.0 INTRODUCTION
On February 28, 2019,Jerry Wylie (NC L.G. #1425) of SynTerra inspected the Mayo
Steam Electric Plant(Mayo or Site) property for existing and potential new seeps.
Inspection activities were performed in accordance with North Carolina Environmental
Management Commission (EMC) Special Order by Consent WQ #S18-005. That Special
Order by Consent(SOC) describes inspection requirements as follows:
Duke Energy shall conduct annual comprehensive surveys of areas down gradient of ash
basins identifying new seeps, and documenting the physical characteristics of previously
documented seeps. All examinations of seeps must include identification of seeps by
approximate latitude and longitude and date-stamped digital photographs of their
appearance. A report summarizing the findings of the surveys, including a section
analyzing the effect decanting of the basin(s) has on seep flows, accompanied by copies of
the photographs noted above ("Annual Seep Report"), shall be submitted to DWR in
conjunction with submittal of the April 30 quarterly report noted in 2(c)(2)above. This
Annual Seep Report must list any seep that has been dispositioned (as described below)
during the previous year, including an analysis of the manner of disposition.
Each location documented as a seep at issuance of the SOC, as listed in Table 1 of the
SOC, was observed and documented with photographs during the inspection.
General observations include:
• No previously unidentified seeps were observed during the inspection.
• No noteable changes to seep status were observed during the inspection.
• Decanting had not begun at the time of this inspection.
1.1 Inspection Details
Weather before and during the inspection was clear. Temperatures ranged from
approximately 40 to 50 degrees Fahrenheit (F). There was no precipitation on the day of
the inspection, according to information from the on-Site rain gauge. Information from
the rain gauge indicated there was no precipitation during the three days before the
inspection.
The inspector reviewed previous inspection reports and dam safety inspection reports
pertaining to the ash basin. Cedric Fairbanks (Duke Energy system owner) conducted
the ash basin dam safety inspections and prepared the reports. Ms. Leanne Wilson
(Mayo Plant Environmental Coordinator) and Mr. Fairbanks were interviewed
Page 1-1

• 2019 Annual Seep Report April 2020
Mayo Steam Electric Plant,Duke Energy Progress,LLC SynTerra
concerning recent rainfall, construction/stabilization projects associated with the ash
basins, and general Site conditions in and surrounding the ash basin. Observations from
the dam safety inspection reports were consistent with observations made during the
annual inspection.
The inspection included observations in the following areas (Figure 1):
• Along the perimeter of the ash basin (at the toe of the dam)
• Along the area north of the 1981 Construction and Debris (C&D) Landfill
• Within areas at or below the ash basin water elevation and downgradient and/or
downstream
• Drainage features associated with the basin, including engineered channels
Seep locations and inspection areas are shown on Figure 1. Observations noted during
the inspection are summarized on Table 1. Photographs taken of each seep location
during the inspection are included in Appendix A.
Page 1-2

2019 Annual Seep Report April 2020
Mayo Steam Electric Plant,Duke Energy Progress,LLC SynTerra
2.0 FINDINGS
2.1 General Observations
Inspection observations of each seep are shown in Table 1. Details include:
• No new seeps were observed during the inspection.
• No previously unidentified or unreported pipes were observed during
inspection.
• Ash basin dam toe drains (S-01 and S-02) are enclosed within a confined space.
• A system designed to capture flow from S-01 and S-02 and from nearby seep
locations — including S-01A, S-02A, and S-02B — is in operation.
2.2 Effects of Decanting
Decanting of the ash basin at Mayo had not yet begun at the time of this inspection.
2.3 Changes to Seep Status
Mr. Wylie inspected each seep to evaluate whether it may be dispositioned in
accordance with the SOC. The requirements for dispositioning a seep are as follows:
For purposes of this Special Order, "dispositioned" includes the following: (1) the seep is
dry for at least three consecutive quarters; (2) the seep does not constitute, and does not
flow to, waters of the State or Waters of the United States for three consecutive quarters;
(3) the seep is no longer impacted by flow from any coal ash basin as determined by the
Director of DWR in accord with applicable law and best professional judgment; or (4) the
seep has been otherwise eliminated (e.g., through an engineering solution). If a seep that
has been dispositioned through drying up reappears in any subsequent survey, such a
seep will no longer be deemed dispositioned and can be subsequently re-dispositioned as
specified above. Non-constructed seeps described in paragraph 1(h) of this SOC cannot be
dispositioned through option (2) above.
No changes to seep status were observed during this inspection.
Page 2-1

• 2019 Annual Seep Report April 2020
Mayo Steam Electric Plant, Duke Energy Progress, LLC SynTerra
3.0 REFERENCES
North Carolina Department of Environmental Quality. (2018). Special Order by Consent
EMC SOC WQ S18-005.
Page 3-1

• 2019 Annual Seep Report April 2020
Mayo Steam Electric Plant,Duke Energy Progress, LLC SynTerra
FIGURE

'
.
mot.
lb
,.. ,:-: .., • NORTH CAR(A(APPROXIMATE STATE LINE E „.
)! 60'RIGHT-OF-WAY
■ MAYO I
/'..'— EKE R0. •
1
. 'I —_—_ 1
1, ---7;-.1.Z.-1 t--1 \/
// _ ..Wit+¢-• .��l _-_ -_ ww�rr��--
FRR I S 01 t S 02A S-'01 --- _— --— ---— SETTLING ■
I I [S-02B BASIN
J ) t
j s
S0
r .. A�
>1;2"" , a. - .- . ,, - _ • ' ' ' '
`� I) APPROXIMATE 1981 v.-
ASH BASIN
Y LANDFILL
\ AREA
\% 1 100'RAILROAD e ' w +" 'S-05), t (CLOSED)
V A� 'RIGHT-OF-WAY:/// "r ) i -
i 1 I
.\
. "-°ao" 1 r MAYO RESERVOIR "`
I ( W.E.433.0±
Po
p
/,/
`
1 1 1 I LINED ' ,,
) , . )S, 4
I>" RETENTION ;
t
)I ,3, BASIN ,
/ / hr AREA
! f 1 GYPSUM r . '
) I
/ I
100'HWY 50 f I i I /// STORAGE
w A. ,' )
-`,
Y .
AREA �► {•
".. POWER PLANT
°
/ / A; COAL aJ. "`„ . • /•
, •
/ / I I A STORAGE t
�
i ' PILE `'
,/,/ I r AREA - r LEGEND
r ' I [ CONSTRUCTED SEEP(APPROXIMATE)
I — ,,�, NON-CONSTRUCTED SEEP(APPROXIMATE)
Ifr "• , -` DISPOSITIONED SEEP(APPROXIMATE)
'`� •`• ,• I 1 SPECIAL ORDER BY CONSENT(SOC)INSPECTION
S-09
+'�."� AREA
NOTES:
1.SPECIAL ORDER BY CONSENT(SOC)LOCATIONS ARE DESCRIBED IN EMC SOC WO '+' ASH BASIN WASTE BOUNDARY
S18-005. 5-06
S o •—• GEOGRAPHIC LIMITATION
2 THE WATERS OF THE U.S.DELINEATION HAS NOT BEEN APPROVED BY THE U.S.
ARMY CORPS OF ENGINEERS AT THE TIME OF THE MAP CREATION.THIS MAP IS A "- ' - -" '//- ---- RIGHT-OF-WAY(DUKE ENERGY PROPERTY)
PRELIMINARY JURISDICTIONAL DETERMINATION ONLY.THE PRELIMINARY WETLANDS
AND STREAMS BOUNDARIES WERE OBTAINED FROM AMEC FOSTER WHEELER .:+�
ENVIRONMENTAL&INFRASTRUCTURE,INC.NATURAL RESOURCES TECHNICAL -�' +-\ • DUKE ENERGY PROGRESS PROPERTY
REPORT(NRTR)FOR MAYO STEAM ELECTRIC PLANT DATED JANUARY 2014 AND �� az
UPDATED ON JULY 11,2018 TO REMOVE ONE PREVIOUSLY MISIDENTIFIED WETLAND • �•!■ 1• STREAM(AMEC NRTR 2014)
NEAR THE ASH BASIN DISCHARGE CHANNEL. WETLAND(AMEC NRTR 2014)
' f ak 3.SAMPLE LOCATIONS WERE DERIVED FROM VARIOUS SOURCES AND ARE A MIX OF ;„,e,,, _ aill
SURVEYED AND APPROXIMATE LOCATIONS.THEREFORE,SAMPLE LOCATIONS ARE
APPROXIMATE. 1DUKE GRAPHIC SCALE
Illi " w i
481.) 500 o soo i.000 FIGURE 1
4.ALL BOUNDARIES ARE APPROXIMATE. ENERGY (IN FEET) SOC LOCATIONS AND INSPECTION AREAS
- MJIIiNSLN '
5. MAYO PLANT PROPERTY BOUNDARY PROVIDED BY DUKE ENERGY PROGRESS. r - . ^, -!. +' 1 PROGRESS 2019 ANNUAL SEEP REPORT
�' DRAWN BY:A.ROBINSON DATE:05/03/2019
6.AERIAL PHOTOGRAPHY OBTAINED FROM ESRI ONLINE ON JUNE 10,2019.AERIAL c 1 REVISED BY:A.ROBINSON DATE:03/19/2020
WAS COLLECTED ON FEBRUARY 6,2017. ` 0CHECKED BY:J.WYLIE DATE:03/19/2020 MAYO STEAM ELECTRIC PLANT
APPROVED BY:J.WYLIE DATE:03/19/2020 ROXBORO, NORTH CAROLINA
7 DRAWING HAS BEEN SET WITH A PROJECTION OF NORTH CARD LINA STATE PLANE synTerrd PROJECT MANAGER:1.WYLIE
COORDINATE SYSTEM FIPS 3200(NAD83). '
.-- . .:.:- www.s nterracor..com

TABLE 1
SOC LOCATIONS AND DESCRIPTIONS - 2019 INSPECTION
2019 ANNUAL SEEP REPORT
MAYO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, ROXBORO, NC
Location Coordinates Receiving
Facility Sample ID Receiving Waterbody Waterbody Description SOC Monitoring Interim Action Levels Notes from Inspection
Latitude Longitude Classification
NA - Flow is collected and
pumped back to NPDES Constructed seep. Water level in box is low
permitted wastewater system and sump is active. Evidence of sediment
Mayo S-01 36.538849 -78.893512 in accordance with the NA Seep flow from west toe drain. NA NA transport from upslope gravel and riprap is
pumping system's design present around the area surrounding the box
capacity. structure.
Minor seep forming within filter bed at the Monitoring in An area of rip rap and gravel at the toe of the
Mayo S-01A 36.538903 -78.89351 UT to Crutchfield Branch B toe of the west dam and flowing into an Crutchfield Branch NA - 2B Standards Apply west side groin ditch of the dam. Minimal flow
downstream of all seepbeneath/around ripr
UT to Crutchfield Branch. eneat /around rap.p Seep captured by
flow contributions collection system.
NA - Flow is collected and
pumped back to NPDES-
Mayo S-02 36.537964 -78.891364 Permitted wastewater system NA Seep flow from east toe drain. NA NA Constructed seep. Water level in box is low
in accordance with the and sump is active.
pumping system's design
capacity.
Minor seep forming within filter bed 20 Monitoring in
Mayo S-02A 36.538005 -78.891611 Crutchfield Branch B feet upslope of east dam toe drain (S-02) Crutchfield Branch NA - 2B Standards Apply Dry. Seep captured by collection system.
collection box, flowing into Crutchfield downstream of all seep
Branch. flow contributions
Monitoring in Seep is adjacent to east toe drain structure in
Minor seep forming just downgrade of S- area of rip rap at the toe of the east side groin
Mayo S-02B 36.537989 -78.891339 Crutchfield Branch B 02 collection box, flowing into Crutchfield Crutchfield Branch NA - 2B Standards Apply of the ash basin dam. Flow downslope and
Branch. downstream of all seep along/within groin on east side of the toe drain
flow contributions
structure.
NA - Seep
Mayo S-03** 36.538654 -78.890714 Crutchfield Branch B Sampling location; not a seep Dispositioned NA - Seep Dispositioned Dispositioned. Not a seep.
Mayo S-04** 36.538896 -78.89341 Crutchfield Branch B Sampling location; not a seep NA Seep NA - Seep Dispositioned Dispositioned. Not a seep.
Dispositioned
NA - Seep
Mayo S-05** 36.535039 -78.891693 Mayo Reservoir WS-V Ash basin sampling location, not a seep Dispositioned NA - Seep Dispositioned Dispositioned. Not a seep.
* Seep flow to small channel that originates NA - Seep
Mayo S-06 36.521971 -78.88526 Mayo Reservoir WS-V southeast of power plant. Flows to Mayo Dispositioned NA - Seep Dispositioned Historical sample location. Dispositioned.
Reservoir.
Page 1 of 2

TABLE 1
SOC LOCATIONS AND DESCRIPTIONS - 2019 INSPECTION
2019 ANNUAL SEEP REPORT
MAYO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, ROXBORO, NC
Location Coordinates Receiving
Facility Sample ID Receiving Waterbody Waterbody Description SOC Monitoring Interim Action Levels Notes from Inspection
Latitude Longitude
Classification
Intermittently observed area of wetness
downslope from former production well
location. No flow observed during recent NA Seep
Mayo S-07* 36.521798 -78.892152 Mayo Reservoir WS-V evaluations. Any flow would drain Dispositioned NA - Seep Dispositioned Historical sample location. Dispositioned.
southeast, merging with flow at S-06
before reaching Mayo Reservoir. From
sampling - no CCR impacts.
Area of emergence is a small pool (-3 ft x 6
Monitoring in ft) with little discernible flow that increases
Seep forms one ridge over (east) from downslope. A small, wet, muddy area is
Crutchfield Branch
Mayo S-08 36.537502 -78.890398 Crutchfield Branch B east toe drain, flowing northwest in small downstream of all seep NA - 2B Standards Apply present near sign (east) flowing across leaf
channel to Crutchfield Branch. flow contributions litter with iron floc present. About 50 feet
uphill is an area of emergence in a scour
channel that flows towards and into channel.
Natural stream flow to Mayo Reservoir
originating southeast of plant. Location is NA - Seep
Mayo S-09* 36.522902 -78.886868 Mayo Reservoir WS-V upstream of, and flowing toward S-06. Dispositioned NA - Seep Dispositioned Historical sample location. Dispositioned.
From sampling - no CCR impacts.
Seep is located to the southeast of S-03 on a
Monitoring in hillside between two topographic draws.
Minor seep to small channel, flowing Crutchfield Branch Shallow flow was present in the channel
Mayo S 10 36.538422 -78.890395 Crutchfield Branch B northwest into Crutchfield Branch. downstream of all seep NA 2B Standards Apply directly below sign. Flow increased downslope
flow contributions and crossed the monitoring well access road
and continued into Crutchfield Branch.
Prepared by:JAW Checked by: PWA
Notes:
* -Location previously investigated as a seep.Monitoring has not indicated the presence of coal combustion residuals.
-Seep dispositioned via repair and/or non-flowing condition to potentially reach Waters of the U.S.,or other,as noted. Monitoring shall be conducted at the approximate locations indicated on the attached site map.
All monitoring shall be conducted per the requirements found in Attachment B of this Order.
2B- 15A NCAC 02L.0202 Standard
CCR-Coal Combustion Residuals
ft-feet
NA-Not Applicable
NPDES-National Pollutant Discharge Elimination System
SOC-Special Order by Consent
UT-Unnamed Tributary
Page 2 of 2

• 2019 Annual Seep Report April 2020
Mayo Steam Electric Plant,Duke Energy Progress,LLC SynTerra
APPENDIX A
PHOTOGRAPHS

• 2019 Annual SOC Report April 2020
Mayo Steam Electric Plant-Duke Energy Progress, LLC SynTerra
179°S(T) 136°32'19"N,78°53'36"W*16.4ft A 418ft
„.„,,...,.._,, ,,,. AOW ,-
s-oi
A:7 r-- r
_ i--
F t
'�Zr
AI
S-01 View of constructed seep location,facing down(top of photo is to the
south).
Nl I NE E
0 28°NE(T) 0 36°3221"N,78°53.37"W±32 8ft ♦394ft
S-01A 14,
4 ,
G .e ?`e-.
, f.
1 1
.... t.4..
•
S VIA
.144. un t02550
S-0 1;A View of seep location facing northeast.
alms i&
Page 1 of 7

• 2019 Annual SOC Report April 2020
Mayo Steam Electric Plant-Duke Energy Progress,LLC SynTerra
S isw W
PO 210 2to
1 • • I • I • I • I • 1 • 1 • I • 1 • 1 • I • I • I • I
O 220°SW(T) •36°32'15"N,78°53'28"W*32.8ft ♦390ft
.,,I/Ap
c L
dii
f,
a
at
S-02 View of constructed seep location facing southwest.
5," ♦ sw l' o
• I •.t . 1. 49 • 1„• I • I • I • i • I • I • I • I • I
O 231°SW(T) 7i 36°32'16"N,78°53'29"W±16.4ft ♦387ft
I . .."1 riir, . '
. 4
• T. •••-• \.
d':•,, J
J \
T106,
•
► �!+ r
' le
,ii
' #fir ..' M '°, '4 j
S-02A View of seep location facing sou th,\l,,t
Page 2 of 7

• 2019 Annual SOC Report April 2020
Mayo Steam Electric Plant-Duke Energy Progress, LLC SynTerra
---simmumimiiiimirmiumr----
O 185•S(T) *36°32'16"N,78.53'30"W±98.4ft ♦332ft
�. ti' j
;, ",4 ,k, W4 4. ., ,- ;
1G. ..
i
0$. Ars
4.14
ti-01 li View of seep location facing south.
----------- lijijillIlgr-----
®69°E(T) 7 36°3218"N,78°53.26"W.32.8ft ♦427ft
•
t e weir! '
y^j V
y .•
. .•ice. '
aw •, -,,- . _ 4,
y'
., fit. ' h•
y.° Y '28 Feb 2019,0t34:08
-O3 View of dispositioned seep location facing northeastMEW VIIIIIIIIIIIMI...
Page 3 of 7

' 2019 Annual SOC Report April 2020
Mayo Steam Electric Plant-Duke Energy Progress,LLC SynTerra
NE E SE S
30 6;, 00 20 150 180
1 . I . 1 . I . . I . • . 1 . 1 . • I . • . I . I . I . 1 .
0 101°E (T) O 36°32'20"N,78°53'36"W±16.4ft ♦ 426ft
i a.,.
s
.
t. ! r
J 4~`':t'i/ ` t a
..citik
' ' aa liT' �F p ♦ 1:1:1 , n , O u }•Al 14" ` I* � lu ! ;1 _.a
S-04 View of dispositioned seep location facing east.
No photo provided.Location was dispositioned prior to issuance of SOC because it 4
is not a seep.Location was an ash basin location.
S-0a
........ .2. ,
Page 4 of 7

2019 Annual SOC Report April 2020
Mayo Steam Electric Plant-Duke Energy Progress,LLC SynTerra
No photo provided.Location was dispositioned prior to issuance of SOC based on
no CCR impacts.Location is a historical sampling location.
S-06
No photo provided.Location was dispositioned prior to issuance of SOC based on
no CCR impacts.Location is a historical sampling location.
I S-07
Page 5 of 7

• 2019 Annual SOC Report April 2020
Mayo Steam Electric Plant-Duke Energy Progress,LLC SynTerra
®245°SW(T) ®36°3214"N,78°53'25"W±16.4ft ♦449ft
0 Y
Fes.In p. 1 ✓' z
1 1.
y
4 * *4- 64,1h: - ‘-,1• '. •*.e•+%P ' „kol
cy .!
S-08 View of seep location facing west.
No photo provided. Location was dispositioned prior to issuance of SOC based on
no CCR impacts.Location is a historical sampling location. 1
S-(l9
Page 6 of 7

• 2019 Annual SOC Report April 2020
Mayo Steam Electric Plant-Duke Energy Progress,LLC SynTerra
NVV N NE
S)355°N M •36.32'18"N,78°53'25"W*16.4ft ♦408ft
r:
4 <
�
y..
_ k. .
1
,,
.. -
... . .
t., , 'w} r '_ r _ ,t, o
r
i a L s*-.
! :'•'7 4-t'
' i°9 ." •
e w
a i'
• A.
R 4lib
5 2.
S-10 View of seep location facing north.
0143°SE(T) •36°32'18"N,78°53'26"W*32.8ft ♦293ft
pit
14
rrr 1•` i
`�# fig
+, ,„44.44Y? t
..
1
S-10 \ 1raw of seep location facing southeast.
Page 7 of 7