NC0003417_FINAL HF_Lee_CAP 11-02-2015_20151103

161P
synTerra
CORRECTIVE ACTION PLAN
PART 1
Site Name and Location:
H.F. Lee Energy Complex
1199 Black Jack Church Road
Goldsboro, North Carolina 27530
Groundwater Incident No.:
Not Assigned
NPDES Permit No.:
NC0003417
Date of Report:
November 2, 2015
Permittee and Current
Duke Energy Progress, LLC.
Property Owner:
410 South Wilmington Street
Raleigh, NC 27601
[phone]
Consultant Information:
SynTerra
148 River Street
Greenville, South Carolina
[phone]
Latitude and Longitude of Facility:
N 35.373212 / W-78.089031�,,w`���hl
-
love,,
SE,q�
2026 s'
Justin Mahan, NC PG 2026
Project Manager
Webb N (418
of t Dicp4
y �' 7'28 w
a k0�
s,��, /V W

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
H.F. LEE ENERGY COMPLEX — CORRECTIVE ACTION PLAN PART 1
EXECUTIVE SUMMARY
North Carolina General Assembly Session Law 2014-122, the Coal Ash Management
Act (CAMA) of 2014, requires the owner of a coal combustion residuals surface
impoundment to submit a Groundwater Assessment Plan (GAP) to the North Carolina
Department of Environmental Quality (NCDEQ, formerly Department of Environment
and Natural Resources) no later than December 31, 2014 and a Groundwater
Assessment Report referred to as a Comprehensive Site Assessment (CSA) no later than
180 days after approval of the GAP. A Groundwater Corrective Action Plan (CAP) is to
be submitted no later than 90 days from submittal of the CSA, or a time frame otherwise
approved by NCDEQ not to exceed 180 days from submittal of the CSA. The CAP shall
include, at a minimum, all of the following:
a. A description of all exceedances of the groundwater quality standards, including
any exceedances that the owner asserts are the result of natural background
conditions.
b. A description of the methods for restoring groundwater in conformance with the
requirements of Subchapter L of Chapter 2 of Title 15A of the North Carolina
Administrative Code and a detailed explanation of the reasons for selecting these
methods.
c. Specific plans, including engineering details, for restoring groundwater quality.
d. A schedule for implementation of the CAP.
e. A monitoring plan for evaluating the effectiveness of the proposed corrective
action and detecting movement of any contaminant plumes.
Duke Energy requested a 90-day extension for submittal of the final Groundwater
Corrective Action Plan. The request was based on discussions with NCDEQ that the
CAP would be provided in two parts, with the first part submitted on the original due
date and the second part submitted 90 days later. The CAP Part 1 reports (submitted 90
days after the CSA reports) are to include:
167 Background information,
41' A brief summary of the CSA findings,
0 A brief description of site geology and hydrogeology,
'611 A summary of the previously completed receptor survey,
Page ES-1
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
0 A description of 2L and 2B exceedances,
0l Proposed site -specific groundwater background concentrations,
0 A description of the site conceptual model (SCM), groundwater flow and
transport model and geochemical model.
Part 2 will include the remainder of the CAP requirements including:
101 Risk assessment,
y Alternative methods for achieving restoration,
101 Conceptual plans for recommended corrective actions,
17 Implementation schedule, and
'41, Plans for effectiveness monitoring and reporting.
This CAP Part 1 has been prepared for the Duke Energy Progress, LLC (Duke Energy)
H. F. Lee Energy Complex, and provides additional evaluation of the CSA data
reported on August 5, 2015. Duke Energy has recommended that the ash basins be fully
excavated with the material safely recycled or reused in a lined structural fill
(https://www.duke-energy.com/pdfs/SafeBasinClosureUpdate_HFLee.pdf, accessed on
July 29, 2015). The ash removal under the recommendation would be the primary
source control measure. The results of modeling to evaluate the effects of the ash
removal on groundwater are presented in Section 4 of this CAP Part 1. A description of
exceedances of the groundwater quality values, including provisional background
values are presented in Section 2.
ES-1. Introduction
Duke Energy Progress, Inc. (Duke Energy), owns and operates the H.F. Lee Energy
Complex (Lee Plant), located near Goldsboro in Wayne County, North Carolina (Figure
1-1). Three coal-fired units were retired in September 2012, followed by four oil -fueled
combustion turbine units in October 2012. In December 2012, the H.F. Lee Combined
Cycle Plant fueled by natural gas was brought on-line. Coal ash has been managed in
the Plant's on -site ash basins, which include three inactive ash basins located to the west
of the plant operations area, an active ash basin and Lay of Land Area (LOLA) northeast
of the operations area. The management areas contain approximately 5,970,000 tons of
ash (https://www.duke-energy.com/pdfs/duke-energy-ash-metrics.pdf, accessed on July
17, 2015).
The Lee Plant site exhibits typical Coastal Plain geology with layered soil deposits and
shallow water table conditions. Boron exhibits the largest area of distribution in
Page ES-2
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
SynTerra
shallow groundwater in the immediate vicinity of the ash basins. Arsenic is
consistently present in samples from several monitoring wells within the boron plume.
Shallow groundwater flows from uplands north and west of the ash management areas
to the east, southeast, and south toward the Neuse River. There are no known users of
shallow groundwater downgradient of the ash basin. Private water wells are located
upgradient of the ash basins. One public water supply well that draws water from a
deep aquifer is located approximately 2,000 feet north and upgradient from the inactive
basins. The area surrounding the Lee Plant has access to public water supply.
ES-2. Site Conceptual Model
The CSA determined that leaching of CCR impounded within the ash basins impacts
groundwater in the immediate vicinity of the ash basins as shown on Figures ES-1 and
ES-2. Cross sections conceptually illustrating conditions at the site are provided as
Figures ES-3 through ES-8. Based on the CSA and compliance monitoring results,
groundwater flow is toward the Neuse River (south for the active basin, east to
southeast for the inactive basins and north for the LOLA). Water within the active ash
basin and inactive ash basin 1 is hydraulically higher (upgradient) than the surrounding
land surface. Pore water drains through the underlying soil to the groundwater.
Groundwater and seeps are the primary mechanisms for migration of ash -related
constituents to the environment. Elimination of the hydraulic head within the ash
basin, either by placing an impermeable cover on the ash or by removing the ash,
would eliminate migration of ash pore water into the subsurface.
Geochemical factors that affect groundwater quality in the surficial aquifer in the
vicinity of the ash basins include variations in pH, redox potential (Eh), and dissolved
oxygen (DO) that are attributed to mixing of groundwater from upland areas with ash
pore waters and wetland conditions near groundwater monitoring wells. Cobalt, iron,
vanadium and manganese are ubiquitous in groundwater samples from the site.
Provisional site background concentrations for these constituents are provided herein to
determine the extent of ash influence. Sorption tests on soils from the site indicate that
iron and manganese leach from naturally occurring materials. While it is known that
these metals leach from coal ash, occurrences in background areas limit their use as
indicators of groundwater contamination. Geochemical modeling indicates that only a
small fraction of the sorptive capacity of the soils at the site has been consumed.
The ash basins, surficial deposits, the Black Creek and the Cape Fear deposits make up
distinct hydrogeologic layers at the Lee site. Groundwater in the surficial deposits
under the ash basins flows horizontally to the east and south and discharges into the
Neuse River or Halfmile Branch. This flow direction is away from the nearest public
Page ES-3
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
SynTerra
and private water wells. The surficial aquifer groundwater discharge to surface water
provides a boundary for groundwater migration.
The hydrogeologic and geochemical data are consistent with observed conditions that
indicate migration of CCR constituents to, and potentially beyond, the compliance
boundary is limited to boron and arsenic at the east side of the active basin. The
horizontal migration of boron and arsenic in the surficial groundwater best represent
the dominant flow and transport system. Downward vertical migration is restricted
due to the clay and silt layers beneath the ash basins that act as confining layers over the
deeper aquifers in the area.
ES-3. Extent of 2L and 213 Exceedances
Constituent concentrations in excess of 2L or IMAC detected in monitoring wells
screened in the surficial aquifer include pH, antimony, arsenic, barium, boron,
chromium, cobalt, iron, lead, manganese, sulfate, thallium, total dissolved solids (TDS),
and vanadium. Exceedances of antimony (IMAC), barium, chromium, sulfate and
thallium (IMAC) are limited in extent. TDS exceedances are restricted to samples from
monitoring wells screened beneath the ash basins. Iron and manganese exceedances of
2L have been detected in nearly all samples collected from surficial wells across the site
since monitoring was first initiated in 2010. Vanadium was first sampled in
groundwater as part of the CSA. Vanadium occurrences in excess of IMAC are
scattered and include both upgradient and downgradient areas.
Surface water samples from upland areas had pH values less than the 2B standard of
6.0. Aluminum was detected above 2B in surface water samples collected from upland
(background) surface waters and the Neuse River. Boron, a coal ash indicator that does
not have an associated 2B standard has been detected in surface waters and springs
near the ash basins.
ES-4. Receptor Survey
Land use surrounding the Lee site includes commercial, rural residential, agricultural,
and forest land. Beaverdam Creek, Halfmile Creek, and the Neuse River border the Lee
Plant. Public water service in the area is provided by Fork Township Sanitary District.
ES-4.1 Public Water Supply Wells
Surveys of public and private water supply wells within a 1/2 mile radius of the
ash basin compliance boundaries have been conducted. One Fork Township
Sanitary District water supply well is located approximately 2,000 feet
upgradient (north) of the inactive basins. The well was sampled at the direction
of NCDEQ during 2015. The next two closest public water supply wells are
Page ES-4
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
located approximately 1 mile to the northeast and 1 mile south and across the
Neuse River from the site. These wells reportedly produce water from the Upper
Cape Fear Aquifer and bedrock.
ES-4.2 Private Water Supply Wells
Inventories of public and private water supply wells have been compiled.
NCDEQ contacted nearby residents regarding private wells and managed the
sampling of the wells in accordance with CAMA. Based on results of the water
supply well sampling, NCDEQ recommended that nine of the residences use
bottled water rather than well water. The recommendations were based on
results for cobalt, chromium, manganese and vanadium which were above 2L or
IMAC. Groundwater modeling results included with this CAP and data
collected for the CSA will be used to further evaluate the probability that 2L
exceedances for private water wells are associated with the presence of the ash
basins. The updated survey indicates that approximately 97 private water
supply wells may be located within or in close proximity to the 0.5 mile radius of
the compliance boundary.
ES-4.3 Human and Ecological Receptors
A screening level human health and ecological risk assessment was performed as
a component of the CSA Report (SynTerra 2015). Preliminary human health and
ecological conceptual exposure models were prepared as part of the screening
level risk assessment. Each model identified the exposure media for human and
ecological receptors. Human health exposure media includes potentially
impacted groundwater, soil, surface water and sediments. The exposure routes
associated with the potentially complete exposure pathways evaluated for the
site include ingestion, inhalation and dermal contact of environmental media.
Potential human receptors include residential, recreational users, and industrial
workers.
The potential exposure media for ecological receptors includes impacted soil,
surface water and sediments. Direct contact with groundwater does not present
a complete exposure pathway to ecological receptors. Exposure routes
associated with potentially completed exposure pathways include incidental
ingestion and ingestion of prey or plants. Potential ecological receptors include
aquatic receptors (e.g., fish, benthic invertebrates), semi -aquatic receptors (e.g.,
piscivorous birds, piscivorous mammals), terrestrial receptors (e.g., terrestrial
invertebrates, plants, small and large mammals, passerine birds, raptors).
Page ES-5
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Samples were collected and analyzed for the purposes of characterization and
comparison to established water, soil, and sediment quality criteria as published
by the US EPA and/or NCDEQ. Comparison of upgradient constituent
concentrations to downgradient constituent concentrations aids in determination
of areas of potential concern for human and ecological receptors.
Results of the SLERA, analyzed in the context of background data, indicate that
many constituents that exceed screening criteria occur at naturally elevated
levels in the area. There are, however, some constituents in various media that
are found at greater concentrations in source areas than in background or other
receiving areas. These potential risks will be evaluated as part of the risk
assessment in the CAP Part 2.
ES-5. Geochemical Modeling Results
Results of geochemical modeling yield the following observations:
E1, Sorption modeling indicates that aquifer solids have sufficient sorption capacity
for high concentrations of all constituents though the actual sorbed
concentrations will vary based on the sorption affinity (i. e. distribution
coefficient) of individual constituents. Available sorption sites were estimated
based on extractible iron and aluminum concentrations.
Retardation or sorption behavior of arsenic, selenium and vanadium is related to
the oxidation state.
'67 Sorption of arsenic increases upon oxidation of As(III) to As(V), the latter is the
likely dominant state of arsenic at the Lee Plant as a result of prevalent lower pH
values. This leads to a decrease in mobility of As.
161, Selenium oxidation from Se(IV) to Se(VI) occurs at higher pH values. Overall
lower pH values and the lack of oxidizing conditions at higher pH locations at
the Lee Plant, results in a lack of mobility of selenium.
01 Vanadium also has strong sorption at lower pH values and decreased mobility in
these conditions. However, vanadium has multiple oxidation states in aqueous
environments, which can lead to increased mobility of lower states if proper
oxidation is not maintained.
`0 Barium, zinc, cobalt and lead sorption is primarily influenced by pH. Sorption
increases with increasing pH.
Boron is relatively inert and exhibits little sorption affinity. This leads to it being
highly mobile in groundwater.
Page ES-6
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Modeled distribution coefficients for boron are significantly lower than
experimentally derived values. This indicates there is a mechanism limiting
aqueous concentrations of boron which is accounted for in the sorption model.
This may be related to substitution for silicon in micas or co -precipitation
reactions with other mineral phases.
ES-6. Groundwater Modeling Results
Groundwater flow and constituent transport modeling was conducted to evaluate the
results of different possible corrective actions at the site. The study consisted of three
main activities: development of a calibrated steady-state flow model of current
conditions, development of a historical transient model of constituent transport that is
calibrated to current conditions, and predictive simulations of the different corrective
action options. Fate and transport of arsenic, boron, iron and manganese were
addressed in the model. Simulations included the following scenarios:
(1) In this scenario the ash basins continue to be managed in their current condition
and no ash is excavated.
(2) Install low permeability surface covers for each ash basin (cap -in -place).
(3) Full excavation of the ash basins and isolation of ash to an off -site lined structural
fill or landfill.
Key results from groundwater fate and transport modeling include the following items:
Calibration to constituent concentrations observed in June 2015 resulted in iron
and manganese impact that extends for short distances (several hundreds of feet)
in all directions from the footprint of the ash basins. This might be expected as a
result of historical sluicing of CCR to the basins. Predicted concentrations
extended beyond the compliance boundaries on the east side of the active basin
and on the south side of the inactive basins. These results lead to the
recommendation for replacement of several background monitoring wells (BW-1,
BGMW-09, BGMW-10, AMW-09BC and DMW-2) and the addition of monitoring
wells on the south side of the inactive basins.
`0 Based on review of the calibration results for iron and manganese there is
potential for historical CCR constituent migration for short distances north of the
inactive basins. Proper abandonment of water supply wells and access to public
water pipelines should be evaluated for parcels between the inactive basins and
Old Smithfield Road.
Page ES-7
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
41P Calibration to constituent concentrations observed in June 2015 resulted in
arsenic and boron impact that extends beyond the compliance boundary east of
the active basin.
In the no ash removal simulation, CCR constituent impact gradually diminishes
as recharge from upland areas dilutes groundwater and pushes constituents
toward the Neuse River. The extent of arsenic and boron to the east of the active
basin does not increase significantly. The farthest extent of the impact is
controlled by the presence of the Neuse River.
y Results of simulations for off -site removal to a lined structural fill or landfill
indicate there is a quicker reduction in extent of groundwater quality impacts.
However, the boron impact beyond the compliance boundary on the east side of
the active basin does not diminish any more quickly.
ES-7. Corrective Actions to be Evaluated Based on Provisional
Background Concentrations
Site -specific background concentrations for soil, groundwater, surface water and
sediment were determined as part of the CAP Part 1. Background locations were
selected for each media based on topographic maps, groundwater elevation maps, the
SCM (discussed further in Section 3), and sample analytical results. Comparison to
provisional background concentrations leads to determination of areas that will be
included in the risk assessment and evaluated for corrective action if needed. Media
will also continue to be monitored for refinement of background conditions.
Observations from the provisional background comparisons are summarized below:
167 Exceedances of provisional background soil concentrations are limited to areas
within the footprint of the ash basin or within the compliance boundaries.
Groundwater exceedances of provisional background are limited to areas within
the basins or compliance boundaries except for the east side of the active basin.
Areas east of the active basin will be further evaluated for corrective action.
47 Surface water, springs or seeps with exceedances of provisional background
concentrations are present adjacent to the inactive basins, the active basin and the
LOLA. Source (ash) removal is expected to diminish both the volume of flow and
the CCR constituent concentrations of these waters. The exceedances will be
considered for corrective action.
41, Sediment exceedances of provisional background concentrations are limited in
occurrence. Additional background concentration development is anticipated.
Page ES-8
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

cat
I J-41
C774L
m
LEGEND
T T'
N
c' c0 N
7
N N N N N N m
i 0, 0 . "t
4 Ar N hil N
0
N N Ni N
4 Y.�
0.
OL
7w
lo
0 0 0
L
3 7�. W,w ON
0 j2--, .
0 0
N N rw N w
A N N
N N N
o
0
S c N N N N N N
000
N N N" N N N
0
's
0.
I &
-t�44'
0 0 A
'o
0 �3 iN
`4 0
i7:V 0
wir
Pco
M .�5 - 0 hhS
Ar 0
0
v
X
'Faft
*411W
4;
x
ALI
w
z
'Ili x W
iy';,
0
NOTES:
D
N N N N c N N N N
Ne(N N N N N N A N N ww mw
N N PthhN gA N N N N N rohN ge
0 Q
ACTIVE Nsfthi A N N N N e
rrhi nN N N N N N N N
4
l'77777 N N N ev e e z
0
ASH BASIN
p N N N N N N N N N
N N ev V e e
w
N N N N N N N N N N N w
N N hhrrhh[V t ngrhi i W 0
...........
t
N
plih h hh i dlhh hh 4hh
Rtiffs —1 OK4-1.A.
V N W
MEy. 0
N AN,
A
—rY W 'J�l
ENERGY
.1, DUKE
. m.4-;g
1',Ll�,-Q.-., 1. sTelrlrad PROGRESS
i of N N EN h" eN N N
p'l m
N hkvrhi i i vvN N N N w
. . . . . . . . ky�t r oom (Yvvv 8N hhpnh
e e
A"
N VW EN N 4 hq VOLI P
N MEN N A hg v#Li p
N VW EN
FIGURE ES-1 SITE CONCEPTUAL MODEL -PLAN VIEW
INACTIVE ASH BASINS
H.F. LEE ENERGY COMPLEX

LEGEND
N N
N N N N N N m
-0 m
Q G eh N hh N
s ' Q +N N NiN m a
Q O N N rw N W
-----
_
1
, N N
N N
' Q� Q•' c N N N
OO Q N N N N
o �
thisQ 'Q7 r N N N" N N N
Q
.OQ` phhs Q +'r s �• :Y,"y�3?e " u *7i"- r'µ'` :"i`,P , .. -' ' a
F
a y' 1 :3 • s 5E
Ji. �• � t rr .3 c
LL
0.0
3 .? ` Q •.� �'YY.. ��' -+may. ; _"1�f f (,+gyp''F - - k s
Y 4, ', - Q, ♦ M
e r,' • ° . - r a+g "°, e mar. f�4 4 �'&
�
70
X' � �'+{� �fr y � \ wM'r '"S Hyy+� b � ,r Ft _ � / / �` �P' � • �_ - r, � k ' a ,� U
A_e a, 4 .:. . � � i • yr • ;; M _ �.''4' 3
T sf vO Rc, a �ywX q Y ,� `•'"'4y",e, I -4 .* a *'. ,r' e• .,y, a
• •'" � t+;. a•.� � .� k'k r,:;k�l 7i_ ` ° +'4.;tf�Xra jr., ��� v ,r d �,5 cV
Active w
$ {..
x� 1� ' �. 'R •• NOTES:
`` r • gJ(- Ash Basin N N N N N N N NW' �
t a
� ._ N N N N c N N N N LL
.rP ` ¢� `• NeN N N N N a N N hhfV m (1 W
-0�
fr t, . '._..� .'..�., - �• `,. ` • N N f$hhN g 6�1 N N N N N fOhN g e Q
�*+4
�� -11 '"*{y"r '�•�..�k -°' Lay Of �`''. `• Nsd*hiA N N N N e Q
v
e s y• • nhi nN N N N N N N N U
Land Area F N N N 6+V e e w
o
4 v N N N N N N N N N
N N N N NN N N N N N
�" rz• * N N hhnhhN t ngrhi i W W
t LL
i
1[ `
1` phh h phh IAthh I hh rrdthh H
V N W
w
—,DUKE o
` ENERGY
G . snTerra PROGRESS N
i of N N EN hhrh a EN N N d
N hkvrhi iivvN N N N >
trooxn avvv EN %pnh a
e e W
c
N N VN EN 1N N vW h qq v qtj p W
N N MEN IN N vWhgv i pY
'^-• - N N eN EN �
FIGURE ES-2
`t SITE CONCEPTUAL MODEL -PLAN VIEW
ACTIVE ASH BASIN
H.F. LEE ENERGY COMPLEX o
0

0
Of
0
Lu INACTIVE ASH BASIN (SOURCE)
WETLAND
co RECHARGE /ASH PORE WATER
ZONE
RIVER BANK
ui
NEUSE RIVER
ASH
y SURFICIAL AQUIFER
-- -S. -- _-- ` -- ---- - - ��
� JAREA OF CONCENTRATIONS IN
CAPE FEAR FORMATION ]GROUNDWATER ABOVE NC 2L STANDARD
�-�
100,
/��i�w/i/vvivv/vivw�/v��/%�/vy vvvwwv//v//�/wiwiv/ .
LEGEND METAMORPHIC BEDROCK!`
Q ASHvvv�-
Q ASH PORE WATER
GROUNDWATER ABOVE NC 2L STANDARD
FOR BORON
GROUNDWATER BELOW NC 2L STANDARD
FOR BORON
INFERRED OR MEASURED
APPROXIMATE WATER TABLE
INFERRED OR MEASURED
♦ APPROXIMATE ASH PORE WATER TABLE
LITHOLOGIC CONTACT
141,
synTerra
NOT TO SCALE
148 RIVER STREET, SUITE 220
GREENVILLE, SOUTH CAROLINA 29601
PHONE [phone]
www.synterracorp.com
DRAWN BY: JOHN CHASTAIN DATE: 10/18/2015
PROJECT MANAGER: JUDD MAHAN
LAYOUT: ES-3 (CURRENT CONDITIONS)
SURFICIAL AQUIFER
FIGURE ES-3
CURRENT CONDITIONS
CROSS-SECTION SITE CONCEPTUAL MODEL
INACTIVE ASH BASIN
H.F. LEE ENERGY COMPLEX
GOLDSBORO, NORTH CAROLINA

ASH BASIN (SOURCE)
POWER LINE ASH PORE WATER
WETLAND DRAINAGE
DITCH
RECHARGE
ZONE
♦
ASH
�- ♦ RIVER BANK LAY -OF -LAND -AREA
_ _ -��_- - SURFICIAL AQUIFER (LOLA)
—
_—— — NEUSE RIVER
---_--- — —_���
—BLACK CREEK CONFINING LAYER=z — — — — ASH
-44
BLACK CREEK AQUIFER
CONFINING LAYER Jw-- — — — +——--�'r---a
LEGEND
Q ASH
Q ASH PORE WATER
GROUNDWATER ABOVE NC 2L STANDARD
FOR BORON
GROUNDWATER BELOW NC 2L STANDARD
FOR BORON
INFERRED OR MEASURED
APPROXIMATE WATER TABLE
INFERRED OR MEASURED APPROXIMATE ASH
♦ PORE WATER TABLE
LITHOLOGIC CONTACT
CAPE FEAR AQUIFER
METAMORPHIC BEDROCK
1417
synTerra
AREA OF CONCENTRATIONS IN
GROUNDWATER ABOVE NC 2L STANDARD
NOT TO SCALE
148 RIVER STREET, SUITE 220
GREENVILLE, SOUTH CAROLINA 29601
PHONE [phone]
www.synterracorp.com
DRAWN BY: JOHN CHASTAIN DATE: 10/19/2015
PROJECT MANAGER: JUDD MAHAN
LAYOUT: ES-4 (CURRENT CONDITIONS)
ASH PORE WATER
COOLING POND
FIGURE ES-4
CURRENT CONDITIONS
CROSS SECTION SITE CONCEPTUAL MODEL
ACTIVE ASH BASIN
H.F. LEE ENERGY COMPLEX
GOLDSBORO, NORTH CAROLINA

0
Q
&
o
INACTIVE ASH BASIN
INACTIVE ASH BASIN
Lu
o
Of
o (SOURCE) o
o
(SOURCE)
o
c�
a
-a
CULVERT
U
0
0
Y
w
Y ASH PORE WATER Y
o
Q
Y
ASH PORE WATER
s
cr
DO
o
/
o
Lu
o
w
ASH ,
_
ASH , ,
m
ACTIVE ASH BASIN (SOURCE)
o
Q
ASH PORE WATER
w
Lu
Y
=
o
�
o WETLAND
w RECHARGE
ASH
z ZONE
■
SURFICIAL AQUIFER SURFICIAL AQUIFER
---��—�-----Z �---- _—_--, SURFICIAL AQUIFER
--------------- - BLACK CREEK CONFINING LAYER ='_
AREA OF CONCENTRATIONS IN —i— —'��
— --- _-_ ----i
GROUNDWATER ABOVE NC 2L STANDARD z BLACK CREEK AQUIFER — S — — — — --
/UVA� A�V'iA i�iAAiAA/VA//V Ai\//VAiAA'VA/\�GAA/�A\i\A\j AA'�,
CAPE FEAR FORMATION
METAMORPHIC BEDROCK
LEGEND
Q ASH
Q ASH PORE WATER
Q GROUNDWATER ABOVE NC 2L STANDARD FOR BORON
Q GROUNDWATER BELOW NC 2L STANDARD FOR BORON
INFERRED OR MEASURED APPROXIMATE WATER TABLE
INFERRED OR MEASURED APPROXIMATE ASH PORE WATER TABLE
LITHOLOGIC CONTACT
AREA OF CONCENTRATIONS IN
GROUNDWATER ABOVE NC 2L STANDARD
CAPE FEAR FORMATION
lo,\\ \
� ii\\�i\�\ '\�\�i/i/\\i\\i\•. , , �i\i'\�\\i\\\'\\i�/i\/i\\i/\\��\\'i\\�i\�/\\i/\\j; \ — z�\\!\i\ �\\i\\i\\�\\''i\��\\i\\�\\�'�\\'�\''��\�\i\\i\\i''�\'/\��\\
-:.wAV�,�.�i.A�A� aV� vAivi G , ,. �!�\isA�V�.v/%/i�iA��AAwA<;v/�,ii�i:AAnAA��- <'.,/���A\.vAfv/%�✓vAyvAA/\��VA�A�wAiCvi�/�iiA�._;
VA''iA�VAiiAA�AiAAA''VA/i�V�AAiVAi�\iAA�V'//AA�iAAiVAi�VA'/VAiV//i�AAAiAAiA,,' S��/\iViA�i��A�AAiAAVi�/iA\�AAiVAiAAA''VA''�AV/AA/iAAiAAi�
//AAAAVA�iVAViiAiVAi/AAAAi'VA'/A\\�AAiAAiVAA �A�i��AAiAAiAAiAA/iV� v H I C BEDROCK
AAiVAiAA�'VA�V'�AA'i\iAAVA�VA� V�AA//A�iAAA �A
NOT TO SCALE
148 RIVER STREET, SUITE 220
AROLINA 29601
>i\�\\�i\�/i\\ij�\�\\'/i�i\\i}i�i\\\''\\/\\'\\i\\i\\i\\\\\\\\i'\\i''\\\/\\ii\i\\i\\\\\i/\\/�\\�����\\/\\\i\\\/�\�\\��\ •
PHONE 864 42� 9999UTH
wwwsynterracorp.com
��r�
DRAWN BY: NAG R JUD IN DATE: 10/15/2015
PROJECT MANAGER: JUDD MAHAN
/i\i\\�.\\�/\//\�/\�/\\�.\��/�\//\//\�/\\\ �\�\�/�//\\/\\J/\\ \\%� j�\j\\%�\\/�\\�\%j//�\jam\\�\\� \\�/\\�\//\\f\\\/\\ � /�\'/i\\%��% •.
\/ " '/ �` \ / ' /'�• \
LAYOUT: ES-5 (PRE SITE CAR)
RI
10/29/2015 253 PM P:\Duke Energy Progress.1026\104. Lee
'\' '
FIGURE ES-5
CURRENT CONDITIONS
CROSS-SECTION SITE CONCEPTUAL MODEL
ACTIVE & INACTIVE ASH BASINS
H.F. LEE ENERGY COMPLEX
GOLDSBORO, NORTH CAROLINA

0
K
W
C7
0
WETLAND
> RECHARGE
o ZONE
w
y SURFICIAL AQUIFER
CAPE FEAR FORMATION
LEGEND
GROUNDWATER ABOVE NC 2L STANDARD
FOR BORON
GROUNDWATER BELOW INC 2L STANDARD
FOR BORON
INFERRED OR MEASURED
APPROXIMATE WATER TABLE
— — LITHOLOGIC CONTACT
FORMER INACTIVE ASH BASIN
(SOURCE REMOVED)
NEUSE RIVER
° — SURFICIAL AQUIFER
AREA OF CONCENTRATIONS IN
GROUNDWATER ABOVE NC 2L STANDARD
CAPE FEAR FORMATION
METAMORPHIC BEDROCK
141,
synTerra
NOT TO SCALE
148 RIVER STREET, SUITE 220
GREENVILLE, SOUTH CAROLINA 29601
PHONE [phone]
www.synterracorp.com
DRAWN BY: JOHN CHASTAIN DATE: 10/15/2015
PROJECT MANAGER: JUDD MAHAN
LAYOUT: ES-6 (SOURCE REMOVAL)
FIGURE ES-6
SOURCE REMOVAL
CROSS-SECTION SITE CONCEPTUAL MODEL
INACTIVE ASH BASIN
H.F. LEE ENERGY COMPLEX
GOLDSBORO, NORTH CAROLINA

POWER LINE
WETLAND DRAINAGE
DITCH
RECHARGE
ZONE
FORMER ASH BASIN
L
` RIVER BANK (LOLA) FORMER
SURFICIAL AQUIFER LAY OF LAND AREA
— _ _ —� _ — NEUSE RIVER
—7—-
Y[7
-!BLACK CREEK CONFININGZ - '- - - BLACK CREEK ACONFINING LAYER ��—�--
LEGEND
GROUNDWATER ABOVE NC 2L STANDARD
0 FOR BORON
GROUNDWATER BELOW NC 2L STANDARD
FOR BORON
INFERRED OR MEASURED APPROXIMATE
WATER TABLE
LITHOLOGIC CONTACT
CAPE FEAR AQUIFER
METAMORPHIC BEDROI
L�
synTerra
AREA OF CONCENTRATIONS IN
GROUNDWATER ABOVE NC 2L STANDARD
NOT TO SCALE
148 RIVER STREET, SUITE 220
GREENVILLE, SOUTH CAROLINA 29601
PHONE [phone]
www.synterracorp.com
DRAWN BY: JOHN CHASTAIN DATE: 10/18/2015
PROJECT MANAGER: JUDD MAHAN
LAYOUT: ES-7 (SOURCE REMOVAL)
COOLING POND
FIGURE ES-7
SOURCE REMOVAL
CROSS-SECTION SITE CONCEPTUAL MODEL
ACTIVE ASH BASIN
H.F. LEE ENERGY COMPLEX
GOLDSBORO, NORTH CAROLINA

= Y
W
Lu
FORMER INACTIVE ASH BASIN Q FORMER INACTIVE ASH BASINCr
Cr
(SOURCE REMOVED) DO (SOURCE REMOVED)
WOr
o
_ - - - Do
J
Q Do
FORMER ACTIVE ASH BASIN
(SOURCE REMOVED)
\I I
�l
SURFICIAL AQUIFER SURFICIAL AQUIFER
— — — — — SURFICIAL AQUIFER
_ _
————— _ _ BLACK CREEK CONFINING LAYERAREA OF CONCENTRATIONS IN
GROUNDWATER ABOVE NC 2L STANDARD \ z BLACK CREEK AQUIFER
AREA OF CONCENTRATIONS IN
GROUNDWATER ABOVE NC 2L STANDARD
CAPE FEAR FORMATION
CAPE FEAR FORMATION
\�\i\\i\\\'\v i\;, \ / .i \ .► i\\ \\''i i\\i\\i\\\'\ >\\i \i
/\
\
✓/\\ \ v ol / \,\ \ ///\ \ \i ✓Y\
//\ //
/\ \ ///\ \ \ //\ \ \/\,\\ \ /r\ \ \ / /\ \ \i/ \,\\ \ ///\ \ //i\ \ \ir \,\\ \ / / i\ \ \i \
,\,\\ \ //\/\ \ //\ \ \ //\\ /,/r\,\ \ //r\ \ \ii //\\ \ //�\,\ \ ///\ \ \i/ //\\ /// i\ \ /r/\ \ \/i ✓/
.METAM RPHI BEDR CK //\ r/ \ \ � ///\ \/ /\\ \ // \ \ `! ///\ \ \\'/ //\ \ / '\,\ \ r//\ \ \/ //\\ \ // \ \ \ r//\ \ \/ , METAM RPHIC BEDR K
0 C 0 \i„v\\ \\ \/// \ \ / /\ \ ///\\ \\ \/✓/\,\ \ ///\ \ \i /\i\\ \\ \i/ \,\ \ ///\ \ \ //\\ \\ \//,\,\ \ //r\ \, 0 OC o/
\r/ //\\ \\w
\ \\�i\,\
FIGURE ES-8
NOT TO SCALE
i \ \ , \ , _ w \, \, !•. it\\/i, ,\\\ \\/i\\ri\\i\\\\\\'/\i\\\�\i'\i'r\\'i\i\i\i\\i\\v /i\\/\\i/\\i\\i\\ i\'i\ /\\i\\i\\i \\'y\\i\\i \\\ \\ \''/\\'r\\i\:
SOURCE REMOVAL
LEGEND \\/\,\�'/\,\ 148 RIVER STREET, SUITE 220 CROSS-SECTION SITE CONCEPTUAL MODEL
?i''\\''r\i\v\\ \\i\\ \\�\'/i\\\\ \\i i \'i\ \i\\j\\ \\\ \i \\ \� \'\\'i\\v\\\\ \� \\�i,\\\/\\ \\ /\\'i\\'i\ '.;
GROUNDWATER ABOVE NC 2L STANDARD FOR BORON i\,\\i\\i\\\/\v\'i\i\,\ \\ \/iri\i \\\/vi/\r/\\i\\\ \\/\'ice/\\ \\ vir/\ \\ \// /\,\\ \v\r�r\ \ \/\ GREENV 61-421-9999 ROLINA29601
'\'����\� `\'\� \\'' \'<�'�\��\�w\\\%��'\\�\\ VIP PHONE ss4-421-9999 ACTIVE &INACTIVE ASH BASINS
GROUNDWATER BELOW N C 2 L STANDARD D FOR BORON %\\iv\\ \\'/i\\i\\i\\\ \\'ri \i\ \\�ir\\i,�\� \ r\\� i\ \ \\ \\\\v\\\i\\ \\i \\ \\'ri\\i\\i\\i\\i \\'\\ \\i\i\\i\\�\ 4\i\ `- yn wwwsynterracorp.com
0 \w%\\ '\'\'\\'/\y `y`` \\> \v \ \\\'\ \\\J \ \\> H.F. LEE ENERGY COMPLEX
INFERRED OR MEASURED APPROXIMATE WATER TABLE !i\ri/\\ \\�\\r\\'i\/�\//\\i\\\r\\'i \/i\\i\\\ \\/ i\r\\ / /\ \` \/' \/\\ \\ \ / �/\ \\ \i' , DRAWN BY: JOHN cHAsrAIN DATE: 10/15/2015
/\ j\\ j\\j/\\/\\\%�\ '\\�\\'\%\\%\\'''\\%\v\\%\\'\\j'\\\'\\`\/\\%\\\'�\''\\%\\%\\\'\\'/'�\\�\\ T
� r� PROJECT MANAGER: JUDD MAHAN G O L D S B O RO, NORTH CA RO L I N A
LAYOUT: ES-8 (POST SITE CAR)
L�THOLOG�CCONTACT \ \/" /' \ \ \' ` `\ ii" ' v /'i•' /� 10/29/2015 2:56 PM P:\Duke Energy Progress.1026\104. Lee Ash Basin GWAssessment\16CorrectiveAction Plan\Figures\Active\DE LEE CAR INACTIVE & ACTIVE X-SECT.dwg

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
TABLE OF CONTENTS
SECTION PAGE
H.F. LEE ENERGY COMPLEX — CORRECTIVE ACTION PLAN PART 1 EXECUTIVE
SUMMARY............................................................................................................................ ES-1
ES-1.
Introduction..........................................................................................................
ES-2
ES-2.
Site Conceptual Model........................................................................................
ES-3
ES-3.
Extent of 2L and 2B Exceedances.......................................................................
ES-4
ES-4.
Receptor Survey...................................................................................................
ES-4
ES-4.1 Public Water Supply Wells.......................................................................
ES-4
ES-4.2 Private Water Supply Wells......................................................................
ES-5
ES-4.3 Human and Ecological Receptors............................................................
ES-5
ES-5.
Geochemical Modeling Results..........................................................................
ES-6
ES-6.
Groundwater Modeling Results........................................................................
ES-7
ES-7.
Corrective Actions to be Evaluated Based on Provisional Background
Concentrations......................................................................................................
ES-8
1.0 INTRODUCTION.........................................................................................................1-1
1.1
Site History and Overview....................................................................................1-1
1.2
Purpose of Corrective Action Plan.......................................................................1-2
1.3
Regulatory Background.........................................................................................1-3
1.3.1 T15A NCAC 02L .0106 — Corrective Action Requirements .....................1-3
1.3.2 Coal Ash Management Act Requirements................................................1-4
1.3.3 Regulatory Standards for the Site Media...................................................1-6
1.3.4 NCDEQ Requirements.................................................................................1-6
1.3.5 NORR Requirements....................................................................................1-6
1.4
Summary of CSA Findings....................................................................................1-6
1.5
Site Description.......................................................................................................1-9
1.6
Site Geology and Hydrogeology..........................................................................1-9
1.7
Receptor Survey....................................................................................................1-10
1.7.1 Summary of Receptor Survey Activities..................................................1-11
1.7.2 Summary of Receptor Survey Findings...................................................1-11
1.7.3 Public Water Supply Wells........................................................................1-11
1.7.4 Private Water Supply Wells.......................................................................1-12
1.7.5 Potential Human Receptors.......................................................................1-12
1.7.6 Potential Ecological Receptors...................................................................1-13
Page i
P:\Duke Energy Progress. 1026 \ 104. Lee Ash Basin GW Assessment\16.Corrective Action Plan\CAP Report\ FINAL\ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
2.0 BACKGROUND CONCENTRATIONS AND EXTENT OF EXCEEDANCES 2-1
2.1 Background Concentration Determination.........................................................2-1
2.1.1 Provisional Background Soil Concentrations ............................................
2-2
2.1.2 Provisional Background Groundwater Concentrations ..........................
2-3
2.1.2.1 Surficial Groundwater..........................................................................
2-4
2.1.2.2 Cape Fear Groundwater....................................................................... 2-5
2.1.2.3 Black Creek Groundwater...................................................................
2-6
2.1.3 Provisional Background Surface Water Concentrations
......................... 2-6
2.1.4 Provisional Background Sediment Concentrations ..................................
2-7
2.2 Exceedances.............................................................................................................
2-8
2.2.1 Soil...................................................................................................................2-9
2.2.2 Groundwater................................................................................................2-10
2.2.3 Surface Water...............................................................................................
2-13
2.2.4 Sediment.......................................................................................................
2-16
2.3 Initial and Interim Response Actions.................................................................2-17
2.3.1 Source Control.............................................................................................2-17
2.3.2 Groundwater Response Actions...............................................................
2-17
3.0 SITE CONCEPTUAL MODEL................................................................................... 3-1
3.1 Site Geology.............................................................................................................
3-1
3.2 Site Hydrogeology..................................................................................................
3-3
3.3 Confining Layers.....................................................................................................3-5
3.4 Shelby Tube Analysis.............................................................................................
3-5
3.5 Site Hydrology........................................................................................................
3-6
3.5.1 Hydraulic Conductivity...............................................................................
3-6
3.5.2 Hydraulic Gradients..................................................................................... 3-7
3.5.3 Groundwater/Surface Water Interaction...................................................
3-7
3.6 Site Geochemistry...................................................................................................
3-7
3.6.1 Source Characteristics...................................................................................
3-8
3.6.1.1 CCR Constituents in Ash Pore Water ................................................
3-8
3.6.2 Groundwater..................................................................................................3-9
3.6.2.1 Redox Conditions..................................................................................
3-9
3.6.2.2 Constituent Distribution in Groundwater ........................................
3-9
3.6.2.3 Facilitated (Colloidal) Transport.......................................................
3-11
Page ii
P:\Duke Energy Progress. 1026 \ 104. Lee Ash Basin GW Assessment\16.Corrective Action Plan\CAP Report\ FINAL\ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
3.6.2.4 Eh/pH/DO Diagrams.......................................................................... 3-11
3.6.2.5 Time Versus Boron Concentration Diagrams ................................. 3-12
3.7 Correlation of Hydrogeologic and Geochemical Conditions to Constituent
Distribution............................................................................................................ 3-12
4.0 MODELING...................................................................................................................4-1
4.1 Determination of Distribution Coefficient.......................................................... 4-1
4.2 Geochemical Modeling.......................................................................................... 4-3
4.3 Numerical Fate and Transport Model.................................................................4-5
4.3.1 Flow and Transport Model..........................................................................4-6
4.3.1.1 Flow Model............................................................................................ 4-6
4.3.1.2 Transport Model.................................................................................... 4-7
4.3.2 Model Results................................................................................................. 4-8
4.4 Groundwater and Surface Water Interactions....................................................4-9
4.4.1 Flow Considerations..................................................................................... 4-9
4.4.2 Concentration of a Constituent................................................................. 4-11
4.4.3 Results........................................................................................................... 4-11
4.4.4 Sensitivity Analysis..................................................................................... 4-12
5.0 CORRECTIVE ACTION PLAN PART 2..................................................................5-1
6.0 REFERENCES................................................................................................................ 6-1
Page iii
P:\Duke Energy Progress. 1026 \ 104. Lee Ash Basin GW Assessment\16.Corrective Action Plan\CAP Report\ FINAL\ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
LIST OF FIGURES
SynTerra
Figure ES-1
Plan View Conceptual Site Model - Inactive Ash Basins
Figure ES-2
Plan View Conceptual Site Model - Active Ash Basin
Figure ES-3
Cross -Section View Conceptual Site Model - Inactive Ash Basins -
Current Conditions
Figure ES-4
Cross -Section View Conceptual Site Model - Active Ash Basin -
Current Conditions
Figure ES-5
Cross Section View - Inactive and Active Ash Basins- Current
Conditions
Figure ES-6
Cross Section View Post Excavation- Inactive Ash Basins- Source
Removal
Figure ES-7
Cross Section View Post Excavation- Active Ash Basins- Source
Removal
Figure ES-8
Cross Section View - Inactive and Active Ash Basins- Source
Removal
1.0 Introduction
Figure 1-1
Site Location Map
Figure 1-2a
Site Layout Map - Inactive Ash Basins
Figure 1-2b
Site Layout Map - Active Ash Basin
Figure 1-3
Geology Map
Figure 1-4a
Drinking Water Well and Receptor Survey - Inactive Ash Basins
Figure 1-4b
Drinking Water Well and Receptor Survey - Active Ash Basin
2.0 Extent of 2L and 2B Exceedances
Figure 2-1a
Areas of Exceedances of Comparative Values in Groundwater -
Inactive Ash Basins
Figure 2-1b
Areas of Exceedances of Comparative Values in Groundwater -
Active Ash Basin
Figure 2-2a
Areas of Exceedances of Comparative Values in Surface Water -
Inactive Ash Basins
Figure 2-2b
Areas of Exceedances of Comparative Values in Surface Water -
Active Ash Basin
Figure 2-3a
Areas of Exceedances of Comparative Values in Soils - Inactive Ash
Basins
Figure 2-3b
Areas of Exceedances of Comparative Values in Soils - Active Ash
Basin
Page iv
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
3.0 Site Conceptual Model
Figure 3-1a
Surficial Water Level Map- Inactive Ash Basin
Figure 3-1b
Surficial Water Level Map- Active Ash Basin
Figure 3-2a
Deep Water Level Map- Inactive Ash Basin
Figure 3-2b
Deep Water Level Map- Active Ash Basin
Figure 3-3
Potential Gradient Between Shallow and Deep Zones
Figure 3-4
Isoconcentration Maps - Eh In Ash Pore Water - Active Ash Basin
Figure 3-5
Isoconcentration Maps - pH In Ash Pore Water - Active Ash Basin
Figure 3-6
Isoconcentration Maps - Eh In Surficial Groundwater - Inactive Ash
Basins
Figure 3-7
Isoconcentration Maps - pH In Surficial Groundwater - Inactive
Ash Basins
Figure 3-8
Isoconcentration Maps -
DO In Surficial Groundwater - Inactive
Ash Basins
Figure 3-9
Isoconcentration Maps -
Eh In Surficial Groundwater - Active Ash
Basin
Figure 3-10
Isoconcentration Maps -
pH In Surficial Groundwater - Active Ash
Basin
Figure 3-11
Isoconcentration Maps -
DO In Surficial Groundwater - Active Ash
Basin
Figure 3-12
Isoconcentration Maps -
Eh In Black Creek Groundwater - Active
Ash Basin
Figure 3-13
Isoconcentration Maps -
pH In Black Creek Groundwater - Active
Ash Basin
Figure 3-14
Isoconcentration Maps -
DO In Black Creek Groundwater - Active
Ash Basin
Figure 3-15
Isoconcentration Maps -
Eh In Cape Fear Groundwater - Inactive
Ash Basins
Figure 3-16
Isoconcentration Maps -
pH In Cape Fear Groundwater - Inactive
Ash Basins
Figure 3-17
Isoconcentration Maps -
DO In Cape Fear Groundwater - Inactive
Ash Basins
Figure 3-18
Isoconcentration Maps -
Eh In Cape Fear Groundwater - Active
Ash Basin
Figure 3-19
Isoconcentration Maps -
pH In Cape Fear Groundwater - Active
Ash Basin
Figure 3-20
Isoconcentration Maps -
DO In Cape Fear Groundwater - Active
Ash Basins
Page v
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
Figure 3-21a Time vs Boron Concentration Graphs - Inactive Ash Basins
Figure 3-21b Time vs Boron Concentration Graphs - Active Ash Basins
4.0 Modeling
Figure 4-1 Computed vs Observed Values
Figure 4-2 Conceptual Figure Illustrating Groundwater Discharge
SynTerra
Page vi
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
LIST OF TABLES
1.0 Introduction
Table 1-1 Ash Pore Water Exceedances
Table 1-2 Groundwater Analytical Results
Table 1-3 Groundwater Exceedances
2.0 Extent of 21, and 2B Exceedances
Table 2-1
Provisional Background Soil Concentrations
Table 2-2a
Provisional Background Surficial Groundwater Values
Table 2-2b
Provisional Background Cape Fear Groundwater Values
Table 2-3
Provisional Background Surface Water Concentrations
Table 2-4
Provisional Background Sediment Concentrations
Table 2-5
Soil Exceedances
Table 2-6
Black Creek Unit Groundwater Exceedances
Table 2-7
Surficial Unit Groundwater Exceedances
Table 2-8
Cape Fear Unit Groundwater Exceedances
Table 2-9
Surface Water and Seep Exceedances
Table 2-10
Sediment Exceedances
3.0 Site Conceptual Model
Table 3-1
Vertical Hydraulic Conductivities of Undisturbed Soil
Table 3-2
In -situ Hydraulic Conductivities
Table 3-3
Horizontal Groundwater Gradients and Flow Velocities
Table 3-4
Potential Gradients between Shallow and Deep Zones
Table 3-5
0.10 Micron Sample Results
4.0 Modeling
SynTerra
Table 4-1 Summary of Distribution Coefficients
Table 4-2 Water Supply Wells in Close Proximity to Inactive Ash Basins
Table 4-3 Summary of the Neuse River Water Quality Upgradient and
Downgradient of Ash Basins
Page vii
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
LIST OF APPENDICES
Appendix A
Duke Energy Background Private Well Sampling
Appendix B
Laboratory Results - 0.1 Micron Filtered Groundwater
Appendix C
Site Sorption Report
Appendix D
Geochemical Modeling Report
Appendix E
Groundwater Modeling Report
SynTerra
Page viii
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
1.0 INTRODUCTION
SynTerra
Duke Energy Progress, LLC. (Duke Energy) owns and operates the H.F. Lee Energy
Complex (Lee Plant) located at 1199 Black Jack Church Road, Goldsboro, North
Carolina. The property encompasses approximately 2,100 acres, including the
approximately 314-acre ash basins (171-acre inactive ash basins and 143-acre active ash
basin). The management areas contain approximately 5,970,000 tons of ash
(https://www.duke-energy.com/pdfs/duke-energy-ash-metrics.pdf, accessed on July 17,
2015). The property includes the cooling pond (Quaker Neck Lake), located to the east
of the plant operations area. The Neuse River flows through the property as shown on
Figure 1-1.
The North Carolina Coal Ash Management Act ( NC CAMA) directs owners of coal
combustion residuals (CCR) surface impoundments to conduct groundwater
assessment, and remedial activities, if necessary. A Comprehensive Site Assessment
Report (CSA) dated August 5, 2015, has been completed for the Site. The CSA was
conducted to collect information necessary to understand potential impact associated
with CCR management areas, the vertical and horizontal extent of potential impact,
identify potential receptors and screen for potential risks to receptors.
CAMA requires the preparation of a Corrective Action Plan (CAP) for each regulated
facility within 270 days of approval of the assessment work plan (90 days within
submittal of the CSA Report). Duke Energy and NCDEQ mutually agreed to a two part
CAP submittal, with Part 1 being submitted within the original due date and Part 2
being submitted 90 days thereafter. Based on the findings of the CSA report and the
requirements of CAMA, this CAP Part 1 presents a synopsis of the CSA and provides
further understanding of groundwater exceedances identified. The CAP Part 1 also
presents results of groundwater flow, groundwater -surface water interaction, and fate
and transport modeling, which will support an evaluation of potential remedial
alternatives and the recommended remedial approach to be provided in the CAP Part 2.
1.1 Site History and Overview
The Lee Plant began operation in 1951. From 1967 through 1971 four oil -fueled
combustion turbine units were added. In 2000 five simple -cycle duel fuel (oil and
natural gas) units were built. Three coal-fired units were retired in September 2012,
followed by the four oil -fueled combustion turbine units in October 2012. The new
combined -cycle plant was brought on line in 2012.
Coal ash has been managed in the Plant's on -site ash basins, which include three
inactive ash basins located to the west of the plant operations area, an active ash basin
Page 1-1
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
and a Lay of Land Area (LOLA) northeast of the operations area (Figures 1-2a and 1-
2b). The ash basins and the LOLA comprise the ash management areas. Discharges
from the active ash basin are permitted by the North Carolina Department of
Environmental Quality (NCDEQ) formerly known as the Department of Environment
and Natural Resources (NCDENR) under the National Pollutant Discharge Elimination
System (NPDES).
Duke Energy has performed voluntary groundwater monitoring around the active ash
basin from July 2007 until April 2010. The voluntary groundwater monitoring wells
were sampled two times each year and the analytical results were submitted to
NCDEQ. Groundwater monitoring as required by the NPDES permit began in October
2010 for the active basin and in October 2011 for the inactive basins. The system of
compliance groundwater monitoring wells required for the NPDES permit is sampled
three times a year and the analytical results are submitted to the NCDEQ. The
compliance groundwater monitoring is performed in addition to the normal NPDES
monitoring of the discharge flows.
Concentrations of boron, iron, manganese and pH in excess of North Carolina
Administrative Code (NCAC) Title 15A, Subchapter 02L.0202 groundwater quality
standards (2L) or the Interim Maximum Allowable Concentrations (IMAC) established
by NCDEQ pursuant to 15A NCAC 02L.0202(c)1 have been measured in groundwater
samples collected at the inactive basin compliance monitoring wells. Concentrations of
arsenic, boron, iron, manganese and pH in excess of 2L are routinely detected in
monitoring wells at the active basin.
Duke Energy recommended in June 2015 that the basins be fully excavated with the
material safely recycled into a lined structural fill (https://www.duke-
energy.com/pdfs/SafeBasinClosureUpdate_HFLee.pdf), accessed on July 29, 2015).
1.2 Purpose of Corrective Action Plan
The final CAP (Parts 1 and 2) are designed to describe means to restore groundwater
quality to the level of the standards, or as closely thereto as is economically and
technologically feasible in accordance with T15A NCAC 02L .0106. Exceedances of
numerical values contained in Subchapter 2L and Appendix 1 Subchapter 02L (IMACs)
at or beyond the compliance boundary will be the basis for corrective action with the
exception of parameters for which naturally occurring background concentrations are
1 Appendix #1 Interim Maximum Allowable Concentrations, lists IMACs. See
http://portal.ncdenr. org/c/document_library/get_file?uuid=2380a642-Of7e-42e2-8e59-
1c32087724af&groupld=38364
Page 1-2
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
greater than the standards. The purpose of the CAP Part 1 is to clarify what constituent
concentrations the owner asserts are background at this time, herein referred to as
provisional background. The CAP Part 1 also provides the modeling data to
understand flow direction, simulations of the ash basin removal and effects on
groundwater.
This CAP contains a synopsis of the CSA report dated August 5, 2015, the results of
predictive groundwater models, and an evaluation of potential corrective actions in
accordance with 15A NCAC 2L Implementation Guidance dated December 6, 1995 for
the constituents that exceed these standards.
1.3 Regulatory Background
In a Notice of Regulatory Requirements (NORR) letter dated August 13, 2014, NCDEQ
requested that Duke Energy prepare a Proposed Groundwater Assessment Work Plan
(GAP or Work Plan) to conduct a CSA in accordance with 15A NCAC 02L .0106(g) to
address groundwater constituent concentrations detected above Title 15, Subchapter 2L
Groundwater Classification and Standards (2L or 2L Standards) at the compliance
boundary.
1.3.1 T15A NCAC 02L .0106 — Corrective Action Requirements
Groundwater corrective action is addressed in T15A NCAC 02L.0106.
"... where groundwater quality has been degraded, the goal of any required corrective
action shall be restoration to the level of the standards, or as closely thereto as is
economically and technologically feasible."
The specific requirements are as follows:
f. Corrective action required following discovery of the unauthorized release of a
contaminant to the surface or subsurface of the land, and prior to or concurrent
with the assessment required in Paragraphs (c) and (d) of this Rule, shall
include, but is not limited to:
(1) Prevention of fire, explosion or the spread of noxious fumes;
(2) Abatement, containment or control of the migration of contaminants;
(3) Removal, treatment or control of any primary pollution source such as
buried waste, waste stockpiles or surficial accumulations of free products;
(4) Removal, treatment or control of secondary pollution sources which would
be potential continuing sources of pollutants to the groundwaters such as
Page 1-3
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
contaminated soils and non -aqueous phase liquids. Contaminated soils
which threaten the quality of groundwaters must be treated, contained or
disposed of in accordance with applicable rules. The treatment or disposal
of contaminated soils shall be conducted in a manner that will not result
in a violation of standards or North Carolina Hazardous Waste
Management rules.
The rule additionally delineates the following requirements for CAPS:
h. Corrective action plans for restoration of groundwater quality, submitted
pursuant to Paragraphs (c) and (d) of this Rule shall include:
(1) A description of the proposed corrective action and reasons for its
selection.
(2) Specific plans, including engineering details where applicable for
restoring groundwater quality.
(3) A schedule for the implementation and operation of the proposed plan.
(4) A monitoring plan for evaluating the effectiveness of the proposed
corrective action and the movement of the contaminant plume.
1.3.2 Coal Ash Management Act Requirements
The Coal Ash Management Act (CAMA) 2014 — General Assembly of North
Carolina Senate Bill 729 Ratified Bill (Session 2013) (SB 729) revised North
Carolina General Statute 130A-309.209 and imposed additional requirements
regarding corrective action at the Site.
In regards to this CAP, Section §130A-309.209 of the CAMA ruling specifies
groundwater assessment and corrective actions, drinking water supply well
surveys and provisions of alternate water supply, and reporting requirements as
follows:
b. Corrective Action for the Restoration of Groundwater Quality. - The owner of a
coal combustion residuals surface impoundment shall implement corrective action
for the restoration of groundwater quality as provided in this subsection. The
requirements for corrective action for the restoration of groundwater quality set
out in the subsection are in addition to any other corrective action for the
restoration of groundwater quality requirements applicable to the owners of coal
combustion residuals surface impoundments.
Page 1-4
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
(1) No later than 90 days from submission of the Groundwater Assessment
Report required by subsection (a) of this section, or a time frame otherwise
approved by the Department not to exceed 180 days from submission of
the Groundwater Assessment Report, the owner of the coal combustion
residuals surface impoundment shall submit a proposed Groundwater
Corrective Action Plan to the Department for its review and approval.
The Groundwater Corrective Action Plan shall provide restoration of
groundwater in conformance with the requirements of Subchapter L of
Chapter 2 of Title 15A of the North Carolina Administrative Code. The
Groundwater Corrective Action Plan shall include, at a minimum, all of
the following:
• A description of all exceedances of the groundwater quality
standards, including any exceedances that the owner asserts are
the result of natural background conditions.
• A description of the methods for restoring groundwater in
conformance with requirements of Subchapter L of Chapter 2 of
Title 15A of the North Carolina Administrative Code and a
detailed explanation of the reasons for selecting these methods.
• Specific plans, including engineering details, for restoring
groundwater quality.
• A schedule for implementation of the Plan.
• A monitoring plan for evaluating effectiveness of the proposed
corrective action and detecting movement of any contaminant
plumes.
• Any other information related to groundwater assessment required
by the Department.
(2) The Department shall approve the Groundwater Corrective Action Plan if
it determines that the Plan complies with the requirements of this
subsection and will be sufficient to protect public health, safety, and
welfare, the environment, and natural resources.
(3) No later than 30 days from the approval of the Groundwater Corrective
Action Plan, the owner shall begin implementation of the Plan in
accordance with the Plan's schedule.
Page 1-5
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex SynTerra
1.3.3 Regulatory Standards for the Site Media
Groundwater samples are compared to North Carolina Groundwater Quality
Standards found in the North Carolina Administrative Code Title 15A,
Subchapter 02L.0202 (2L or 2L Standards) or the Interim Maximum Allowable
Concentrations (IMAC) established by NCDEQ pursuant to 15A NCAC
02L.0202(c). The IMACs were issued in 2010, 2011, and 2012, however DEQ has
not established a 2L for these constituents as described in 15A NCAC
02L.0202(c). For this reason, IMACs noted in this report are for reference only.
Surface water sample analytical results are compared to the appropriate North
Carolina Surface Water and Wetland Standards found in the North Carolina
Administrative Code Title 15A, Subchapter 02B.0200 (2B or 2B standards)
established by NCDEQ and USEPA National Recommended Water Quality
Criteria. The Neuse River is classified as a surface water source for drinking
water. Therefore the standards designated as 'water supply' were included for
comparison. The most conservative of the two values (ecological and human
health) was relied upon in the comparison tables included herein to focus
evaluation of constituents in surface water for additional evaluation in the risk
assessment and corrective action evaluation process.
Compositional (total) soil sample analytical results were compared to NCDEQ
Preliminary Soil Remediation Goals (PSRGs) 'new format' tables for industrial,
residential and groundwater exposures (updated March 2015). Sediment sample
analytical results were compared to USEPA Region 4 Ecological Screening
Values (ESVs).
1.3.4 NCDEQ Requirements
NCDEQ issued site specific requirements for the Site in letters dated November
4, 2014 and February 6, 2015. Specific NCDEQ requirements for the CSA and
CAP attached to the February letter were modified after issuance of the letter and
were finalized in June 2015.
1.3.5 NORR Requirements
The NORR required Duke Energy to comply with 15A NCAC 02L .0106(g),
DWR's Groundwater Modeling Policy, May 31, 2007, and various site specific
requirements.
1.4 Summary of CSA Findings
The CSA focused on evaluation of constituents associated with CCR, such as metals and
other inorganics. NCDEQ prescribed the list of monitoring parameters to be measured
Page 1-6
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
SynTerra
at the Site. Following receipt of the data, parameters were evaluated to assess those
most relevant for the Site. These parameters were determined by examining data from
monitoring wells installed in ash and groundwater.
When water is present below the ash surface and above the base of the basin, it is
referred to as ash pore water. If a constituent concentration exceeded 2L or IMAC in
ash pore water wells, it is considered a constituent that may leach from ash and migrate
into the underlying soil and groundwater. Some constituents are also present in
background monitoring wells and thus require careful examination to determine
whether the presence and concentrations are natural (e.g., rock and soil) or the result of
leaching from the ash basins, or a combination.
A second potential mechanism for the presence of an ash basin to result in groundwater
quality impact can be associated with the changes to natural substrate geochemistry
solubilizing naturally occurring metals from soil to groundwater. This potential
groundwater impact has been evaluated through geochemical analysis and modeling.
The CSA determined that leaching of CCR impounded within the ash basins impacts
groundwater in the immediate vicinity of the ash basins as shown on Figures ES-1 and
ES-2. Constituents leached from ash into ash basin pore water at concentrations greater
than 2L or IMAC include antimony, arsenic, barium, boron, cobalt, iron, manganese,
selenium, thallium, TDS, and vanadium (Table 1-1).
Based on the CSA and compliance monitoring results, groundwater flow is toward the
Neuse River (south for the active basin, east to southeast for the inactive basins and
north for the LOLA). Water within the active ash basin and inactive ash basin 1 is
hydraulically higher (upgradient) than the surrounding land surface. Pore water drains
through the underlying soil to the groundwater or from perimeter dams as seeps.
Groundwater and seeps are the primary mechanisms for migration of ash -related
constituents to the environment. Monitoring well sampling results from CSA activities
are provided on Table 1-2 (CSA Groundwater Analytical Results) and Table 1-3
(Groundwater 2L Exceedances).
The following conclusions are based on scientific evaluation of historical and CSA data:
01 No imminent hazard to human health has been identified as a result of
constituent migration from the ash basins or LOLA.
1611 Recent groundwater assessment results are consistent with previous results from
historical and routine compliance boundary monitoring well data.
Page 1-7
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
01 Upgradient, background monitoring wells contain naturally occurring metals at
concentrations greater than 2L or IMAC. This information is used to evaluate
whether concentrations in groundwater downgradient of the basins are also
naturally occurring, or might be influenced by migration of constituents from the
ash basins. Examples include iron, manganese and cobalt, all present in
background groundwater samples at concentrations greater than 2L or IMAC.
,61P Groundwater in the surficial aquifer under the ash basins flows horizontally to
the east and south and discharges into the Neuse River or Halfmile Branch. This
flow direction is away from the nearest public and private water wells. The
surficial aquifer groundwater discharge to surface water provides a boundary for
migration.
H There are no water supply wells located between the ash basins and the Neuse
River.
H Boron is the primary constituent in groundwater detected at concentrations
greater than background concentrations and 2L. Boron is detected at
concentrations greater than 2L within a three dimensional area beneath and
downgradient of the ash basins in the surficial aquifer, primarily to the southeast
of the active ash basin and beyond the property boundary.
E10 Arsenic is also present in groundwater greater than 2L to the southeast of the
active ash basin.
E1P Rainwater infiltration and standing water in the active ash basin create
mounding and radial flow in the immediate vicinity of the active ash basin. This
would be anticipated to be the case previously, or to a lesser extent under current
conditions, for the inactive ash basins.
N The horizontal migration of boron and arsenic in surficial groundwater best
represent the dominant flow and transport system. Downward vertical
migration is restricted due to the clay and silt layers beneath the ash basins that
act as confining layers over the deeper aquifers in the area.
41, Data indicate the water quality of the Neuse River has not been impacted.
The results of the CSA serve to characterize the horizontal and vertical extent of
ash basin constituent migration, and the groundwater gradients which facilitate
development of the Site Conceptual Model (SCM) (i.e., the groundwater flow and
contaminant migration model). Groundwater modeling included within this
Part 1 CAP allows an evaluation of potential ash removal and other remedies in
regard to restoration of groundwater quality.
Page 1-8
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
1.5 Site Description
The Lee Plant is situated on an approximate 2,100-acre tract in a rural area west of
Goldsboro, NC. The Neuse River flows through the property as shown on Figure 1-1.
The river makes a large bend around the site but is generally flowing from northwest to
southeast. The property includes the cooling pond (Quaker Neck Lake), located to the
east of the plant operations area. The impoundment remains in service. Importantly,
the Neuse River is a groundwater discharge area that effectively controls the potential
impacts associated with the ash basins and the LOLA. Coal ash is no longer generated
at the site.
Coal ash has been managed in the Plant's on -site ash basins, which include three
inactive ash basins located to the west of the plant operations area, an active ash basin
and LOLA northeast of the operations area (Figures 1-2a and 1-2b). The ash basins and
the LOLA comprise the ash management areas. Coal combustion residuals (CCR)
produced from the combustion of coal were sluiced to the ash basins. The ash basins
were developed near original ground surface with some excavation of soils.
Collectively the ash basins encompass approximately 314 acres and contain
approximately 5,970,000 tons of CCR (https://www.duke-energy.com/pdfs/duke-
energy-ash-metrics.pdf, accessed on July 17, 2015).
1.6 Site Geology and Hydrogeology
Field activities conducted as part of the CSA indicate that the lithology beneath the site
generally consists of a layer of silty to clayey surficial deposits underlain by
interbedded clay and sand of the Cape Fear and Black Creek Formations. The Cape Fear
is present beneath surficial deposits at the inactive basins and in areas west of the active
basin. The Black Creek Formation is present beneath the active basin and in areas to the
east. A geologic map illustrating these relationships is included as Figure 1-3.
On the west side of the site, groundwater flows to the east toward the Neuse River.
Downstream from the inactive basins, the Neuse River turns from a northerly direction
toward the east. Groundwater on the east side of the site flows north to south toward
the river from the active ash basin area, and south to north toward the river from the
LOLA. The water table occurs within a few feet of the surface to as much as 15 feet
below ground surface in upland areas.
Water within the active ash basin and inactive ash basin 1 is hydraulically higher
(upgradient) than the surrounding land surface. This leads to groundwater flowing
outward in a radial pattern from the zone of saturated ash for short distances (no more
than several hundred feet) before returning to a natural flow pattern toward the Neuse
Page 1-9
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
SynTerra
River. Groundwater and seeps are the primary mechanisms for migration of CCR
constituents to the environment.
Results from hydraulic gradient calculations using water levels collected from
monitoring wells in June 2015 indicate that there is a potential for upward flow from
deeper zones in areas along the Neuse River. Well pairs in upgradient areas tend to
show a weak potential downward gradient.
Field observations indicate that a confining layer at the top of the Black Creek
Formation is present under the active basin and to the east. The surficial deposits and
the Cape Fear Formation also mitigate vertical migration of CCR constituents. The
surficial deposits include multiple clay beds that are laterally extensive in both the
inactive basin and LOLA areas. The Cape Fear Formation deposits at the site consist of
tightly packed silt which impedes groundwater flow.
1.7 Receptor Survey
The Lee Plant lies in a rural area west of Goldsboro, NC. Properties located within a 0.5
mile radius of the Lee Plant compliance boundary are located in Wayne County, North
Carolina. The surrounding property uses include residential, commercial, and
agricultural. Potable water lines are present along all public roads within a 0.5 mile
radius of the ash basin compliance boundaries.
The surface topography slopes downward toward the Neuse River. Shallow
groundwater moving beneath the ash basins discharges to the Neuse River. The Neuse
River near the Site is not tidally influenced, but the river stage does respond to overland
flow and groundwater flow to the river. Measurements taken at the nearby United
States Geological Survey (USGS) gauging station 02089000 (Neuse River near
Goldsboro, NC [USGS, 2013]) show that the Neuse River water level elevation has
ranged between approximately 45 feet and 63 feet North American Vertical Datum of
1988 (NAVD88).
Perimeter ditches drain the toe of the dam on the north and east sides of the active ash
basin. Locations of subsurface utilities in the plant area to 1,500 feet beyond the basin
boundary are exhaustive and difficult to complete and map with certainty.
Identification of piping near and around the ash basin was conducted by Stantec in 2014
and utilities around the Site property were also included on a 2014 topographic map by
WSP. Due to the isolation of the ash basins from the plant area, subsurface utilities in
the plant area are not expected to be major contaminant flow pathways.
Page 1-10
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Shallow groundwater moving beneath the ash basins discharges to perimeter ditches,
Halfmile Creek or the Neuse River. There are no water supply wells between the ash
basins and surface water discharge features.
1.7.1 Summary of Receptor Survey Activities
Surveys to identify potential receptors including public and private water supply
wells (including irrigation wells and unused or abandoned wells) and surface
water features within a 0.5 mile radius of the Lee Plant compliance boundary
have been reported to NCDEQ (SynTerra, Drinking Water Well and Receptor
Survey, September 2014, and Supplement to Drinking Water Well and Receptor
Survey, November 2014). The first report included results of a review of publicly
available data from NC Department of Environmental Health, NC OneMap
GeoSpatial Portal, DWR Source Water Assessment Program (SWAP) online
database, county geographic information system, Environmental Data Resources,
Inc. records review, the USGS National Hydrography Dataset (NHD), as well as
a vehicular survey along public roads located within 0.5 mile radius of the
compliance boundary. The second report included the results of water supply
well survey questionnaires.
1.7.2 Summary of Receptor Survey Findings
Public water lines serviced by the Fork Township Sanitary District are available
to residences in the area of the site. However, private water wells are also present
in the area. The water supply wells are located upgradient from the ash basins.
1.7.3 Public Water Supply Wells
Public water systems in Wayne County extract groundwater from the Upper
Cape Fear Aquifer according to the website at
(http://www.waynewaterdistricts.com/documents/332/CCR-2014 EDITION.pdf,
accessed on July 7, 2015). One public water supply well has been identified
approximately 2,000 feet north (upgradient) of the inactive basins. Approximate
distances for the public water wells measured from the compliance boundaries
follow:
*7 PWS ID 0496060, Well #not available: 2,000 feet north
'410 PWS ID 0496060, Well #3: 0.9 miles south
0 PWS ID 0496060, Well #4:1.1 miles south
Page 1-11
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
NCDEQ coordinated sampling of the public water supply well located 2,000 feet
north of the site in May 2015 (results reported in the CSA). Results indicated that
iron at 1,450 µg/L and manganese at 317 µg/L exceed the respective 2L of 300
µg/L and 50 µg/L. These concentrations are within the range observed at
background monitoring wells as part of the 2015 groundwater assessment. For
instance, the June 2015 sample from background monitoring well AMW-11BC
contained iron at a concentration of 3,290 µg/L and manganese at a concentration
of 983 µg/L.
1.7.4 Private Water Supply Wells
The receptor survey indicated that no public or private drinking water wells or
wellhead protection areas were located within the potential area of interest
downgradient of the site. Approximately 98 wells (97 private residential wells
and one public well) may be located within or in close proximity to the survey
area. This includes reported wells, observed wells, and possible wells (Figures 1-
4a and 1-4b Drinking Water Well and Receptor Survey).
NCDEQ coordinated sampling of fourteen private water supply wells within 0.5
mile radius of the site (see CSA report for details). Based on results of the water
supply well sampling, NCDEQ recommended that fourteen of the wells not be
used as drinking water supplies. The recommendations were based on results
for cobalt, iron, hexavalent chromium, manganese and vanadium which were
above 2L. Detections of total chromium from monitoring wells in and around the
ash basins have been limited. Because of the limited nature of the total
chromium occurrences, hexavalent chromium analysis has not been conducted
previously for site wells. It will be included in future monitoring in order to
evaluate for this parameter. Groundwater modeling results included with this
CAP and data collected for the CSA will be used to further evaluate whether the
potential that 2L exceedances for private water wells are associated with the
presence of the ash basins.
1.7.5 Potential Human Receptors
An imminent hazard exists whenever it can be demonstrated that the
uncontrolled release of coal ash constituents into the environment has caused
serious harm to public health or the environment, or the threat of harm caused
by an uncontrolled release of coal ash constituents into the environment will
increase substantially before a remedial action plan can be developed.
Emergency remedial measures are warranted when an imminent hazard exists.
Environmental assessment and characterization of onsite environmental media
Page 1-12
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
(groundwater, soil, seepage, surface water, and sediment) within and beyond the
coal ash management compliance boundary (boundaries) to date has determined
that potential risks to human health and the environment posed by constituents
potentially attributable to historical and ongoing management of coal ash within
the basin(s) do not constitute an imminent hazard.
A screening level human health risk assessment was performed as a component
of the CSA Report (SynTerra 2015). Preliminary human health conceptual
exposure models were prepared as part of the screening level risk assessment.
Each model identified the exposure media for human receptors. Human health
exposure media includes potentially impacted groundwater, soil, surface water
and sediments. The exposure routes associated with the potentially complete
exposure pathways evaluated for the site include ingestion, inhalation and
dermal contact of environmental media. Potential human receptors under the
current use scenario include recreational users along with industrial workers.
Potential human receptors under a hypothetical future use scenario include
residents, recreational users and industrial workers. The conceptual exposure
model will continue to be refined consistent with risk assessment protocol, in the
Part 2 CAP.
1.7.6 Potential Ecological Receptors
The Lee site is located in the Southeastern Plains ecoregion of North Carolina,
further divided into the Rolling Coastal Plains ecoregion, with the Neuse River
lying within the Southeastern Floodplains and Low Terraces ecoregion (Griffith,
et al., 2002). Wetland delineation was conducted in 2015 by AMEC Foster
Wheeler, which identified 15 wetland areas and two jurisdictional tributary
segments based on current wetland and stream criteria established by the US
Army Corps of Engineers and NC Division of Water Resources (DWR).
A screening level ecological risk assessment (SLERA) was conducted, which
involved investigation of areas on site with potential for exposure to ecological
receptors (e.g., surface water, seeps, sediment, and soil). Samples were collected
and analyzed for the purposes of characterization and comparison to established
water, soil, and sediment quality criteria as published by the USEPA and/or
NCDEQ. Comparison of upgradient constituent concentrations to downgradient
constituent concentrations, aids in determination of areas of potential concern for
ecological receptors, such as: aquatic receptors (e.g., fish, benthic invertebrates),
semi -aquatic receptors (e.g., piscivorous birds, piscivorous mammals), terrestrial
Page 1-13
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex SynTerra
receptors (e.g., terrestrial invertebrates, plants, small and large mammals,
passerine birds, raptors).
Results of the SLERA, analyzed in the CAP in the context of background data,
indicate that many constituents that exceed screening criteria occur at naturally
elevated levels in the area. There are, however, some constituents in various
media that are found at greater concentrations in source areas than in
background or other receiving areas, such as: arsenic, boron, manganese, and
molybdenum. These constituents have the potential to pose risk to ecological
receptors. These potential risks will be evaluated as part of the risk assessment
in Part 2 of the CAP. Additional details regarding the screening -level risk
assessment can be found in the H. F. Lee CSA report (SynTerra 2015).
Page 1-14
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
2.0 BACKGROUND CONCENTRATIONS AND EXTENT OF
EXCEEDANCES
In accordance with CAMA, the CAP provides a description of all exceedances of
groundwater quality standards, including any exceedances that Duke Energy asserts are
the result of natural background concentrations. Background concentrations are
considered provisional values and will be updated as more data becomes available with
input from NCDEQ.
This section establishes provisional background concentrations for the media of interest
(soil, groundwater, surface water and sediment). Using provisional background data,
the extent of potential ash basin influence can be better understood. Sample results are
then compared to regulatory criteria and background concentrations in order to make
risk assessment evaluations and ultimately determine areas and media where corrective
action evaluation is appropriate.
During the CSA, source areas were defined as the ash basins. Source characterization
was conducted to identify physical and chemical properties of ash, ash basin pore water,
and ash basin seeps. Analytical results for source characterization samples were
compared to 2L or IMAC values, and other regulatory screening levels for the purpose
of identifying constituents that may be associated with potential impacts to soil,
groundwater, and surface water from the source areas. Numerous constituents are
naturally occurring and present in background media and thus require examination to
determine whether the concentrations downgradient of the source areas are naturally
occurring or a result of influence from the source areas.
2.1 Background Concentration Determination
Per 15A NCAC .0106(k), any person required to implement a CAP may propose
alternate background concentrations based on site -specific conditions. Provisional
background concentrations are initially used to identify areas of potential source area
influence. This is intended to expand on the analysis provided in the CSA. Site -specific
background locations were identified for each media (soil, sediment, surface water, and
groundwater). Background locations were selected for each media based on topographic
maps, groundwater elevation maps, the SCM (discussed further in Section 3), historical
analytical results, results of the fate and transport model (discussed in Section 4) and
input from NCDEQ.
Provisional background concentrations have been developed for the parameters with
reported values greater than a standard or criteria. In addition, background
concentrations for constituents which provide an indication of ash basin influence but do
Page 2-1
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
not have established criteria, such as strontium and specific conductance in
groundwater, have also been evaluated as a basis for comparison to determine
horizontal and vertical extent of migration.
Monitoring wells BW-1, BGMW-09 and BGMW-10, which are screened within surficial
deposits, have been used as the compliance monitoring network background locations.
However, based on further evaluation including review of groundwater modeling, these
locations may not represent background conditions. Similarly, monitoring wells AMW-
09BC (located near BGMW-09) and DMW-02 (located near BGMW-10), with well screens
in the Cape Fear and Black Creek deposits, respectively, may not represent background
conditions. Details of groundwater modeling are provided in Section 4.
Therefore, provisional background concentrations are developed based upon analysis of
the CSA data. Additional background data will also be developed and used for further
evaluation in the CAP Part 2.
Where limited background data is currently available, the highest observed background
value for each parameter in each media will be considered the potential provisional
background value unless the data appears to be an outlier or otherwise
unrepresentative. The existing Lee database indicates that some parameters have
background concentrations similar to or greater than measured values in areas
potentially affected by the former ash basins. Where provisional background
concentrations are greater than regulatory criteria such as 2L, 2B, or NCPSRG values,
provisional background values will be the basis for establishing areas for risk assessment
and corrective action evaluations.
As part of the CAP Part 2, a risk assessment will be conducted to identify areas where
correction action evaluations may be needed. This is done by identifying media
locations affected by source areas having a concentration in excess of the appropriate
standard or criteria, or the provisional background value, whichever is greater.
2.1.1 Provisional Background Soil Concentrations
The soil background concentrations will primarily be used to determine if
naturally occurring metals concentrations in soil may leach and lead to
groundwater concentrations greater than 2L or IMAC. The data also provide an
indication of whether naturally occurring soil concentrations are greater than risk -
based human consumption concentrations. However, for the purpose of the
groundwater corrective action plan, the soil to groundwater leaching
concentration is of primary interest.
Page 2-2
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Soil samples collected during installation of background monitoring wells were
used to develop provisional soil background concentrations. These locations
included the following: AMW-11, AMW-12, AMW-13, IMW-01, IMW-02, and
IMW-03. Provisional background soil concentrations were determined as
described above and summarized on Table 2-1. Provisional background soil
concentrations for the parameters antimony, arsenic, cobalt, iron, manganese,
selenium, thallium, and vanadium are greater than applicable PSRGs.
Table 2-1
Provisional Background Soil Concentrations
Analytical
Parameter
North Carolina Preliminary Soil Remediation
Goals
Range of
Observed
Concentrations
Provisional
Background
Concentration
Industrial
Health
Residential
Health
Protection of
Groundwater
Aluminum
100,000
15,000
NE
542 - 9 510
9,510
Antimony
94
6.2
0.9
ND > DL
ND > DL
Arsenic
3
0.68
5.8
1.1 - 8.5
8.5
Cobalt
70
4.6
0.9
1.4 - 47.9
47.9
Iron
100,000
11,000
150
829 - 30 600
30,600
Manganese
5,200
360
65
2.7 - 377
377
Selenium
1,200
78
2.1
0.89 - 1.4
1.4
Thallium
2.4
0.16
0.28
0.62 - 0.84'
0.84'
Vanadium
1,160
78
6
3.1 - 94.8
94.8
Prepared by: CIS
Notes: Checked by:
DMY/EMB
Highlighted values indicate the value selected for comparison
All concentrations reported in
milligrams per kilogram
NE - Not established
ND > DL = No data above detection limit
BOLDED values exceed a Preliminary Soil Remediation Goal
2.1.2 Provisional Background Groundwater Concentrations
Monitoring wells considered in developing the provisional background
concentrations include existing NPDES compliance boundary wells, wells
installed during previous groundwater investigations, and wells recently installed
as part of the CSA.
Page 2-3
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Discussion of monitoring well locations and rationale for inclusion in the
background data set is included in the CSA (August, 2015). As noted in Section
2.1, several compliance well locations (BW-1, BGMW-09 and BGMW-10) have not
been used to develop provisional background concentrations. In general,
background locations are in upgradient areas away from the ash management
areas.
The historical data set was evaluated to exclude sample events associated with
levels of turbidity greater than 10 NTUs.
Regional Background
Many of the constituents that occur in association with CCR management areas
also occur naturally at elevated concentrations. A 2010 state-wide sampling study
for private water supply wells conducted by DEQ (formerly DENR) indicated that
arsenic, chromium, iron and manganese were detected above 21, in significant
numbers of private water supply wells (North Carolina State of the Environment
Report 2011, accessed on 10/30/201 at
http://portal.ncdenr.org/c/document_library/get_file?uuid=3b6484c4-35dd-4139-
b769-a3dc878fce59&groupld=14).
Duke Energy conducted sampling of private water supply wells located between
two and ten miles from the Lee Plant in 2015. The goal of this sampling was to
provide a locally relevant data set beyond potential influence of the ash basins in
order to determine levels of constituents observed naturally near the site. Ranges
of observed concentrations from this study are generally consistent with the
provisional background concentrations provided in this CAP Part 1. Detailed
information as to well construction details and depths were not available. The
private water supply well sampling results serve as a basis for comparison rather
than a tool for background concentration development. The results are
summarized in table format in Appendix A.
2.1.2.1 Surficial Groundwater
Selected background wells for the surficial hydrostratigraphic zone include
AMW-11S, AMW-12S, AMW-13S, IMW-01S, IMW-03S and SMW-02.
Provisional background surficial groundwater concentrations were
determined as described above and summarized on Table 2-2a. Provisional
background surficial groundwater concentrations for the parameters pH,
cobalt, iron, manganese, and vanadium are greater than the 2L or IMAC
(Table 2-2a).
Page 2-4
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
Table 2-2a
Provisional Background Surficial Groundwater Values
Analytical
Parameter
NCAC 2L
Standard
or IMAC
Range of
Observed
Concentrations
Provisional
Background
Concentration
pH
6.5-8.5
4.4 - 5.8
4.4 - 5.8
Antimony
1
ND (<1)
<1
Arsenic
10
ND (<1)
<1
Barium
700
16 - 338
338
Beryllium
4
ND (<1)
<1
Boron
700
ND (<50)
<50
Chromium
10
ND (<1) - 3.78
3.78
Cobalt
1*
ND (<1) - 35.7
35.7
Iron
300
57 - 6,320
6,320
Lead
15
ND (<1)
<1
Manganese
50
20 - 727
727
Selenium
20
ND (<1) - 1.14
1.14
Strontium
NE
26 - 123
123
Sulfate
250,000
11400 - 25,000
25,000
Thallium
0.2*
ND (<0.2)
<0.2
TDS
500,000
47,000 - 210,000
210,000
Vanadium
0.3*
ND (<0.3) - 6.71
6.71
SynTerra
Notes: Created by: TDP Checked by: TCP
Values reported in micrograms per liter for each constituent except pH, which is reported in Standard
Units
* Interim Maximum Allowable Concentration (IMAC) of the 15A NCACO2L Standard, Appendix 1, April
2013
Highlighted values indicate the value selected for comparison
BOLDED values exceed 2L or IMAC
NE - Not established
ND - Not detected above laboratory reporting limit
2.1.2.2 Cape Fear Groundwater
Selected background wells for the Cape Fear hydrostratigraphic zone
include AMW-11BC, AMW-12BC, AMW-13BC, IMW-01BC, IMW-02BC and
IMW-03BC. Provisional background Cape Fear groundwater concentrations
were determined as described above and summarized on Table 2-2b.
Provisional background Cape Fear concentrations for pH, cobalt, iron,
manganese and vanadium are greater than (or outside the pH range for) 2L
or IMAC.
Page 2-5
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
Table 2-2b
Provisional Background Cape Fear Groundwater Values
Analytical
Parameter
NCAC 2L
Standard
or IMAC
Range of
Observed
Concentrations
Provisional
Background
Concentration
pH
6.5-8.5
6.2-8.9
6.2-8.9
Cobalt
1*
ND (<1) - 2.75
2.75
Iron
300
98 - 12,600
12,600
Manganese
50
38 - 1,220
1,220
Strontium
NE
29 - 151
151
TDS
500,000
86,000 - 350,000
350,000
Vanadium
0.3*
ND (<0.3) - 0.962
0.962
SynTerra
Notes: Created by: TDP Checked By: TCP
Values reported in micrograms per liter for each constituent except pH, which is reported in
Standard Units
* Interim Maximum Allowable Concentration (IMAC) of the 15A NCACO2L Standard, Appendix 1,
April 2013
Highlighted values indicate the value selected for comparison
BOLDED values exceed 2L or IMAC
ND - Not detected above laboratory reporting limit
2.1.2.3 Black Creek Groundwater
A background monitoring well screened in the Black Creek
hydrostratigraphic zone has not been established. Voluntary monitoring well
DMW-2 was proposed in the CSA (August 2015) as background location in
the Black Creek zone. However, further evaluation and results of
groundwater modeling suggest it may not be background. A location to the
north of the DMW-2 location will be evaluated for installation of a
replacement background well.
2.1.3 Provisional Background Surface Water Concentrations
Background surface water samples were collected upstream from the inactive
basins along the Neuse River, upstream from the active basin (S-10) and along
two upper branches of Halfmile Creek. The upstream samples from the east (S-
14) and west fork (ISW-HMBREF) of Halfmile Creek were collected in May 2015
adjacent to the bridges on Ferry Bridge Road. Sample ASW-BG serves as a
background location for the active basin and is located on a small stream that
flows from an upland area into the perimeter ditch on the north side of the basin.
It should be noted that NPDES outfalls upgradient in the watershed may create
anthropogenic background influence.
Page 2-6
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Provisional background surface water concentrations were determined as
described above and summarized on Table 2-3. Provisional background surface
water concentrations for the parameters pH, aluminum, cobalt, iron, manganese,
mercury, and vanadium are greater than applicable regulatory criteria.
Additional sample events will be used to further define surface water background
concentrations for the CAP Part 2.
Table 2-3
Provisional Background Surface Water Concentrations
Analytical
Parameter
Surface Water Criteria
NCAC 2B / EPA NRW C
Groundwater
Criteria
Range of
Observed
Concentrations
Provisional
Background
Concentration
Water
Supply
Human
Health
Ecological
NCAC 2L or
IMAC
pH
NE
5-9
6.5-9
6.5-8.5
5.7-7.3
5.7-7.3
Aluminum
6,500
8,000
87
NE
319 - 791
1,910
Antimony
5.6
640
NE
1*
ND (<1)
<1
Arsenic
NE
NE
150
NE
ND (<1)
<1
Arsenic
(TOT)
10
10
NE
10
ND (<1)
<1
Barium
1,000
200,000
NE
700
31 - 102
102
Boron
NE
NE
NE
700
ND (<50)
<50
Chromium
NE
NE
11**
10
ND (<1) - 1.23
1.23
Cobalt
3
4
NE
1*
ND (<1) - 1.54
1.54
Iron
NE
NE
NE
300
897 - 2,900
2,900
Lead
NE
NE
NE
15
ND (<1) - 1.16
2.45
Manganese
50
100
NE
50
30 - 197
197
Mercury
NE
NE
0.012
1
1.4 - 2.24
0.00224
Molybdenum
160
2,000
NE
NE
ND (<1)
<1
Selenium
170
4,200
5
20
ND (<1)
<1
Strontium
14,000
40,000
NE
NE
29 - 63
63
Sulfate
250,000
NE
NE
250,000
2,400 - 15,000
15,000
Thallium
0.24
0.47
NE
0.2*
ND (<0.2)
<0.2
Total
Dissolved
Solids
500,000
NE
NE
500,000
67,000 - 110,000
110,000
Vanadium
NE
NE
NE
0.3*
0.644 - 2.02
2.02
Zinc
I NE
NE
36
NE
ND (<5) - 17
17
Notes: Created by: TDP Checked By: TCP
Values reported in micrograms per liter for each constituent except pH, which is reported in Standard Units
* Interim Maximum Allowable Concentration (IMAC) of the 15A NCACO2L Standard, Appendix 1, April 2013
Highlighted values indicate the value selected for comparison
BOLDED values exceed applicable regulatory values
ND - Not detected above laboratory reporting limit
NE - Not established
2.1.4 Provisional Background Sediment Concentrations
Background sediment samples were collected upstream from the inactive and
active basins along the Neuse River (S-10 and S-16), along two upper branches of
Page 2-7
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment \ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Halfmile Creek (ISW-HMBREF and S-14) and along a small stream that flows
from an upland area into the perimeter ditch on the north side of the active basin
(ASW-BG).
Provisional sediment background concentrations were determined as described
above and summarized on Table 2-5. Provisional background sediment
concentrations for barium and manganese were greater than EPA Region 4
Freshwater Sediment Ecological Freshwater Screening Values.
Table 2-4
Provisional Background Sediment Concentrations
EPA Region 4
Provisional
Analytical
Ecological
Range of Observed
Background
Parameter
Screening
Concentrations
Concentration
Values
Arsenic
9.8
ND (1.5) - ND (8.2)
<8.2
Barium
20
2.8 - 75.6
75.6
Cobalt
50
ND (6.1) - ND (8.2)
<8.2
Iron
20,000
855 - 12,000
12,000
Manganese
460
5.2 - 575
575
Notes: Prepared by: CJS Checked By: DMY
Values reported in milligrams per kilogram for each constituent
Highlighted values indicate the value selected for comparison
BOLDED values exceed applicable regulatory values
ND - Not detected above laboratory reporting limit
2.2 Exceedances
Soil, sediment, surface water and groundwater results from samples collected
downgradient of the ash basins as part of the CSA and a previous investigation
conducted by Geosyntec Consultants were used to evaluate the distribution of
constituents and assess the areas of potential influence. A risk assessment conducted as
part of the CAP Part 2 will be used to further assess potential corrective action
evaluation.
Of the constituents that exceed an applicable regulatory value or provisional
background concentration, boron, pH, sulfate, and TDS are detection monitoring
constituents listed in 40 CFR 257 Appendix III of the USEPA's Hazardous and Solid
Waste Management System; Disposal of Coal Combustion Residuals from Electric
Utilities (CCR Rule). The USEPA considers these constituents to be indicators of
groundwater contamination from CCR as they move rapidly through the surface layer,
relative to other constituents, and thus provide an early detection of whether
Page 2-8
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
contaminants are migrating from the CCR unit. Additional details regarding the CCR
Rule and applicable constituents can be found in the CSA report (SynTerra 2015).
Tables 2-5 through 2-10 compare sample analytical results to regulatory criteria and
background values. Sample locations are shown on Figures 1-2a and 1-2b.
2.2.1 Soil
The following describes the observed exceedances in downgradient area soils
compared to the greater of regulatory screening levels or provisional background
concentration.
Inactive Basins
The following CCR constituents were present at the indicated sampling locations
at the inactive basins above the greater of either the PSRG for the protection of
groundwater or the provisional background concentration.
47 Aluminum - IABMW-1, IABMW-2 and IABMW-3
E1 Arsenic - PZ-04 and PZ-07
10 Manganese - DMW-3
161 Selenium - PZ-04 and PZ-07
,61 Thallium - PZ-04 and PZ-07
The locations are shown on Figure 2-3a.
Active Basins
The following CCR constituents were present at the indicated sampling locations
at the active basin above the greater of either the PSRG for the protection of
groundwater or the provisional background concentration.
,01 Antimony - PZ-02
,61 Arsenic - ABMW-01 and PZ-02
101 Manganese - AMW-04 and PW-01
161 Selenium - ABMW-01, AMW-06R and PZ-02
161 Thallium - PZ-02
The locations are shown on Figure 2-3b.
Page 2-9
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
LOLA
The following CCR constituents were present at the indicated sampling locations
at the LOLA above the greater of either the PSRG for the protection of
groundwater or the provisional background concentration.
y Aluminum - LLMW-01 and LLMW-02
1611 Manganese - LLMW-02
The locations are shown on Figure 2-3b
Constituent concentrations of soils beneath the ash basins tend to be higher for
aluminum, arsenic and selenium compared to background soil concentrations.
Two out of four soil borings with exceedances of provisional background for
manganese (AMW-04 and DMW-03) are located between the ash basins and the
Neuse river bank. Both locations are within the compliance boundaries and
therefore are not identified as background locations. However, the relatively high
manganese concentrations in soil (even when compared to most soil samples from
beneath the basins), may be a result of conditions associated with proximity to the
river rather than proximity to the ash basins.
2.2.2 Groundwater
Where groundwater data indicate that a constituent exceeds the greater of an
applicable regulatory value or the provisional background concentration, the area
is interpreted to be influenced by the presence of the source areas.
Inactive Basins - Surficial
Areas where current or historical data suggest influence for surficial zone
groundwater in the vicinity of the inactive basins are illustrated on Figure 2-1a.
The following CCR constituents were present at the indicated monitoring well
screened within surficial deposits at the inactive basins above 2L and the
provisional background concentration (Table 2-7).
01 Antimony - PZ-05 and PZ-08
01 Arsenic - PZ-05, PZ-06, PZ-07 and PZ-08
10 Boron - BW-01, CW-03, IABMW-02S, PZ-04, PZ-05 and PZ-08
01 Chromium - CW-01
41, Cobalt - IABMW-02S and SMW-03
Page 2-10
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex SynTerra
47 Iron - BW-01, CW-01, CW-02, CW-03, CW-04, IABMW-01S, IABMW-02S,
IABMW-03S, PZ-04, PZ-05, PZ-06, PZ-07, SMW-03, SMW-04, and SMW-05
0 Lead - CW-01
,67 Manganese - BW-01, CW-03, CW-04, IABMW-01S, IABMW-02S, IABMW-03S,
PZ-05, SMW-03 and SMW-05
`7 Selenium - BW-01
,67 Sulfate - PZ-05 and PZ-08
0 Thallium - PZ-04, PZ-05 and PZ-06
t7 TDS - CW-01, IABMW-02S, PZ-04, PZ-05 and PZ-08
All monitoring well locations listed above are either in the footprint of the
inactive basins or within the compliance boundary.
Inactive Basins - Cape Fear
Only one downgradient monitoring well, DMW-03, is screened within Cape Fear
deposits. Groundwater samples from DMW-03 historically exceed 2L and
provisional background concentrations for cobalt, iron and manganese (Table 2-
8).
Monitoring well DMW-03 is located within the compliance boundary between the
inactive basins and the Neuse River.
Active Basins - Surficial
Areas where current or historical data indicate influence for surficial zone
groundwater in the vicinity of the active basins are illustrated conceptually on
Figure 2-1b.
The following CCR constituents were present at the indicated monitoring wells
which are screened within surficial deposits at the active basin above 2L and/or
the provisional background concentration.
y Arsenic - ABMW-01S, CMW-06, CMW-06R, CMW-10 (one sample from
December 2010), MW-01 and MW-03
y Boron - ABMW-01S, CMW-05, CMW-06, CMW-06R, CMW-08, MW-01, MW-
02 and MW-03
y Chromium - CMW-10, MW-01, and MW-04
Page 2-11
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex SynTerra
41, Iron - ABMW-01S, AMW-14S, BGMW-10, CMW-06, CMW-06R, CMW-07,
CMW-10, MW-01, MW-02, MW-03 and MW-04
y Lead - MW-01, MW-03 and MW-04
01 Manganese - ABMW-01S, CMW-06, CMW-08, CMW-10, MW-02, MW-03, and
MW-04
,67 Thallium - MW-01 and MW-04
,67 TDS - ABMW-015, MW-01 and MW-03
Monitoring well BGMW-10 is included for exceedances of the iron provisional
background, however iron concentrations at those levels have not been observed
in this well since October 2013. All other monitoring well locations listed above
are either in the footprint of the active basin or within the compliance boundary.
Active Basin - Cape Fear
Monitoring well AMW-09BC is screened within Cape Fear deposits. It was
installed as part of CSA activities in 2015 and was proposed as a background
location. However, it has since been removed from the background list due to
results of groundwater modeling reported in Section 4 suggest it may not reflect
background conditions.
It was sampled in March and June 2015. The March 2015 sample exceeded 2L for
TDS. The June 2015 TDS concentration was below 2L.
Active Basins - Black Creek
Areas where current or historical data indicate influence for groundwater
occurring in the Black Creek deposits in the vicinity of the active basins are
illustrated conceptually on Figure 2-1b. One well, DMW-02, was considered as a
background well for Black Creek deposits. However, groundwater modeling
results reported in Section 4 indicate that the DMW-02 location may be influenced
by CCR constituents from the active basin. Therefore, provisional background
concentrations have not been determined for Black Creek data. Until a
background well is established, 2L will continue to be used for comparison
purposes (Table 2-6).
The following CCR constituents were present above 2L at the indicated
monitoring wells which are screened within the Black Creek deposits.
10 Cobalt - CTMW-01
Page 2-12
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex SynTerra
E1, Iron - AMW-06RBC, AMW-14BC, AMW-15BC, CTMW-01, DMW-01 and
DMW-02
Manganese - AMW-06RBC, AMW-1413C, AMW-1513C, CTMW-01, DMW-01
and DMW-02
Thallium - AMW-14BC
Vanadium - AMW-06RBC, AMW-15BC and DMW-02
All monitoring wells listed above are located in areas east of the active basin. A
background well for the Black Creek Formation will be installed northeast of
DMW-02 outside of the area identified by groundwater modeling as potentially
influenced by the presence of the active basin.
LOLA - Surficial
Areas where current or historical data indicate influence for surficial zone
groundwater in the vicinity of the LOLA are illustrated conceptually on Figure 2-
1b.
The following CCR constituents were present at the indicated monitoring wells
which are screened within surficial deposits at the LOLA above 2L and/or the
provisional background concentration (Table 2-7).
,61, Arsenic - LLMW-02S
y Barium - LLMW-02S
% Iron - LLMW-02S
`1, Manganese - LLMW-01S and LLMW-02S
01 Thallium - LLMW-01S
Monitoring wells LLMW-01S and LLMW-02 are within the footprint of the LOLA.
2.2.3 Surface Water
Where surface water or spring data indicate that a constituent exceeds the greater
of an applicable regulatory value or provisional background concentration, the
risk assessment will be used to further evaluate the area. These areas are
discussed below.
Inactive Basins
Two branches (west and east) of Halfmile Creek join just north of the inactive
basins. Halfmile Creek bisects the inactive basin area and then flows into the
Page 2-13
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Neuse River. One sample location downstream of the basins and upstream of the
Neuse (S-15) was sampled in August 2014 and May 2015. A low-lying area (S-18)
near the Neuse River is present at the inactive basins. Samples from these surface
water features have been compared to 2B and provisional background
concentrations (Table 2-9).
The following CCR constituents were present in surface water or spring samples
above 2B and the provisional background concentration as shown on Figure 2-2a.
[0 Aluminum - S-17 and S-18
,67 Arsenic - S-18
10 Boron - S-18
161P Chromium - S-18
47 Cobalt - S-15
161P Iron - S-15, S-17, and S-18
,61P Lead - 5-18
47 Manganese - S-17 and S-18
y Mercury - S-18
The S-18 sample location is in a low-lying, swampy area between inactive basin 2
and the Neuse River. Based on review of historical topographic maps, this area
was likely part of the Halfmile Creek drainage before it was re-routed as part of
construction of the inactive basins. Depending upon the season and recent
precipitation, the feature may consist of a small area of standing water or may
provide limited flow into the Neuse River.
Page 2-14
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Active Basins
A small stream flows from an upland area north of the active basin and joins a
system of perimeter ditches that ring the basin. The ditches discharge to the
Neuse River at a location west of the basin and at a location east of the basin.
Seasonally, water flows from swampy areas northeast of the basin and joins the
ditch system on the east. Additionally, a number of springs are located in the area
between the south side of the basin and the Neuse River. The springs flow for a
short distance, normally less than 100 feet, into the Neuse River. Samples from
these surface water features have been compared to 2B and provisional
background concentrations (Table 2-9).
The following CCR constituents were present in surface water or spring samples
above 2B and the provisional background concentration as shown on Figure 2-2b.
Aluminum - S-22, S-24A and S-26
�? Arsenic - S-22, S-23, S-24, S-24A, S-25, S-26, S-02, S-03, S-04, S-07 and S-09
167 Barium - S-22 and S-24A
`7 Boron - S-22, S-23, S-24, S-24A, S-25, S-26, S-02, S-03, S-04, S-07 and S-09
E7 Chromium - S-22
167 Cobalt - S-24
167 Iron - S-20, S-21, S-22, S-23, S-24, S-24A, S-25, S-26, S-01, S-02, S-03, S-04, S-06,
S-07 and S-09
E7 Lead - S-22
E7 Manganese - S-20, S-22, S-23, S-24, S-24A, S-25, S-26, S-02, S-03, S-04, S-07, S-
09 and S-21
01 Mercury - S-23
01 Molybdenum - S-07
17 Sulfate - S-22
17 Thallium - S-04 and S-09
167 TDS - S-22, S-26, S-02 and S-03
,61 Vanadium - ASW-NR01, S-03A, and S-06
161 Zinc - S-01
Page 2-15
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
The surface water and spring sample locations listed above are located within the
compliance boundary of the active basin. A number of samples are from different
locations along the same water feature. For example, S-02, S-03 and S-03A are
samples at different locations along one perimeter ditch. Based on groundwater
modeling results, upon removal of the ash within the basin and re -grading of the
basin to drain, both volume of flow and CCR constituent impact to these waters is
expected to diminish.
LOLA
Ponded water collects in the east side of the LOLA. This surface water was
sampled in March and August 2015. A limited number of springs are also present
between the LOLA and the Neuse River (Table 2-9).
The following CCR constituents were present in surface water or spring samples
above 2B and the provisional background concentration (Figure 2-2b).
101 Aluminum - LOLAS -01A and LOLAS-01B
y Arsenic - LOLAS-01A and LOLAS-01B
�� Chromium - LOLAS-SW-01
y Iron - LOLAS-01A and LOLAS-01B
47 Manganese - LOLAS -01, LOLAS-01A, LOLAS-01B and LOLAS-SW-01
,61P Mercury - LOLAS-01B
01 Vanadium - LOLAS-01
The ponded water inside the LOLA area is not expected to remain after ash
removal. With removal of the ash from the area, both volume of flow and CCR
constituent impact to the springs is expected to diminish.
2.2.4 Sediment
Where sediment data indicate that a constituent exceeds an applicable regulatory
value or a site -specific background maximum concentration, then risk assessment
and corrective action evaluation will be considered in the CAP Part 2. These areas
are indicated below.
Inactive Basins
Sediment was collected from the Halfmile Creek streambed at the S-15 sample
location. No exceedances of EPA RSLs were observed.
Active Basins
Page 2-16
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Stream sediment was collected at selected representative locations at surface
water features around the active basin. Exceedances of screening and background
values are summarized in Table 2-10.
Regulatory exceedances are summarized below.
,61P Arsenic - S-03A, S-04, and S-24
10 Barium - S-24
0 Cobalt - S-04
,61P Iron - S-24
0 Manganese - S-03A
Sediment exceedances associated with the active basin will be evaluated as part of
the risk assessment to be provided in the CAP Part 2.
LOLA
Due to the lack of streams, no sediment samples have been collected from the
LOLA.
2.3 Initial and Interim Response Actions
2.3.1 Source Control
Duke Energy recommended in June 2015 that the basins be fully excavated with
the material safely recycled into a lined structural fill. Coal ash from the Lee plant
under that recommendation would be beneficially reused as structural fill
material at the former Colon clay mine in Lee County, NC.
2.3.2 Groundwater Response Actions
Based on the CSA results and analysis of provisional background concentrations,
CCR constituent impact is present beyond the compliance boundary at the east
side of the active basin. There are no water supply wells in the area between the
east side of the active basin and the Neuse River. The area is heavily forested,
low-lying and is mapped as wetlands. CCR constituent impact will be evaluated
as part of the risk assessment. Strategies such as groundwater extraction wells or
installation of an interceptor trench are anticipated to be evaluated with the CAP
Part 2.
Page 2-17
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
3.0 SITE CONCEPTUAL MODEL
SynTerra
The site conceptual model (SCM) is an interpretation of processes and characteristics
associated with hydrogeologic conditions and constituent interactions at the Lee Plant
site. The purpose of this SCM is to evaluate areal distribution of constituents with
regard to site -specific geological/ hydrogeological and geochemical properties at the Lee
site. The SCM was developed using data and analysis from the CSA and fate and
transport modeling, and based on discussions between Duke Energy and NCDEQ.
Additional discussion of the models is provided later in this report following a
discussion of modeling results.
3.1 Site Geology
Figures ES-3 through ES-8 show conceptual cross sections through the active and
inactive basins at current conditions and after site closure. The sections show the key
hydrostratigraphic units, direction of groundwater flow, and area of groundwater
exceedances for boron.
Clay and/or silt beds are present at multiple levels beneath the site. Portions of the
surficial aquifer, especially on the west side of the site, include plastic clay beds that
vary in thickness from one to approximately 9 feet thick. The Black Creek Formation is
present on the east side (active basin area) of the site. The uppermost part of the Black
Creek Formation is a thick (approximately 25 feet) clay unit that serves as the Black
Creek confining unit. The Cape Fear Formation is the deepest unconsolidated geologic
unit in the area. It is present immediately beneath surficial deposits on the west side of
the site (inactive basins), and is inferred to be present beneath the Black Creek
Formation to the east (active basin). Observations from multiple soil borings at the site
indicate that the Cape Fear sediments are clay and silt -rich. Generally, where sands or
gravels are present in the Cape Fear, they occur in a fine-grained matrix which
effectively lowers the hydraulic conductivity.
The geology of each basin area is summarized below.
Inactive Basins
In the inactive basin area, surficial deposits are generally underlain by the Cape
Fear formation which consists of red to white to yellow silts and clays. Often the
Cape Fear sediment may appear only slightly damp to nearly dry in core
samples below the groundwater table. Cape Fear sediment fabrics are variable.
They range from massive, with little to no apparent layering, to finely laminated
at a millimeter or centimeter scale. They may also occur with laminations
oriented at irregular angles and/or as apparently nodular or concentric.
Page 3-1
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Moderately indurated claystone clasts that range in size from 1 to 3 centimeters
are commonly disseminated throughout the Cape Fear sediments and may occur
as distinct layers usually in clay.
Surficial deposits contain more clay at shallow depths in the inactive basin area
than to the east on the active basin side of the site. For instance, surficial deposit
clays ranging from 5 to 8 feet thick are present immediately beneath ash in the
inactive basins (IABMW-1, IABMW-2 and IABMW-3). Due to the shallow
occurrence of metamorphic rock as evidenced by outcrops of slate on the inactive
side of the site, surficial deposits may directly overlie metamorphic rock in some
areas.
Active Basin
Surficial deposits also overlie the Cape Fear Formation to the west of the active
basin (AMW-04BC, AMW-913C, AMW-1113C, AMW-12BC, and AMW-13BC).
The transition normally includes a change in sedimentary fabric. The surficial
deposits are more often massively bedded, whereas Cape Fear sediments
commonly exhibit irregular laminated bedding often incorporating claystone
clasts.
Similar to the inactive ash basin area, Cape Fear sediments generally occur as
clays and silts or as sands in a clayey to silty matrix. They are often moderately
consolidated; though do not appear to be cemented. Fresh core samples may
appear only slightly damp to nearly dry upon inspection. Coarser material is
present at times, but is usually encased in a matrix of clay and silt that might
lower the effective hydraulic conductivity. Minor lenses of sand occur at various
levels, especially towards the base of the formation as noted in boring logs for
AMW-11 and AMW-9. Winner and Coble (1996) noted that sands of the Cape
Fear Formation are poorly sorted and possess a clay matrix in most areas of the
Inner Coastal Plain.
From the active basin toward the east, the Black Creek Formation, underlies the
surficial deposits. The formation exhibits a distinct clay layer at the top that
grades with depth to a succession of clayey to silty sands interbedded with clays.
The distinct clay layer at the top of the Black Creek ranges from 15 to 25 feet. It is
a generally plastic, gray to dark gray to black, clay that contains varying amounts
of sand and silt. This clay bed is interpreted as the Black Creek confining unit.
The middle to lower portions of the clay are colored dark with carbonaceous
organic matter and lignitic wood. According to Lautier (2001) clay beds in the
lower part of the Yorktown Formation of Miocene age may be incorporated into
Page 3-2
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
SynTerra
the Black Creek confining unit in northern Wayne County. However, due to the
absence of shell material, which is prevalent in the Yorktown, and the presence
of features common to the Black Creek Formation the clay unit is considered part
of the Black Creek Formation.
In borings on the east side of the active ash basin (AMW-6RBC, AMW-14BC,
AMW-15BC), the distinctive clay unit is underlain by interbedded, carbonaceous
clays and sands identified as Black Creek Formation. The contact between the
Black Creek Formation and underlying Cape Fear Formation was not observed
in borings at the active basin.
LOLA
Three borings were conducted in ash (LLMW-1, LLMW-2 and LLMW-3 and two
borings (LLMW-1S and LLMW-2S) were conducted to a shallow level (-25 feet)
beneath ash at the LOLA. Observations from these borings indicate that the ash
is underlain by a clay layer with sandy interbeds that ranges from 8 to 9 feet
thick. It is interpreted as alluvium and part of the site -wide surficial deposits. A
Shelby Tube sample was collected from this portion of the surficial deposit at the
LLMW-1 location from 10 to 12 feet below ground surface (bgs). Physical
analysis indicated the sample consisted of 74.8 percent sand. However, the
vertical hydraulic conductivity result, 9.5 x 10-8 cm/sec, indicates that the fine
grained clay fraction is controlling the hydraulic conductivity. As observed in
the boring for LLMW-1S, the clay bed appears to be part of a repeating alluvial
sequence that consist of cobbles and gravel at the base, fining upward to sands
and then clay.
3.2 Site Hydrogeology
The ash basins, surficial deposits, the Black Creek and the Cape Fear deposits make up
distinct hydrogeologic layers at the Lee site. The initial zone of saturation beyond the
limits of the ash basins occurs in surficial alluvial sediments. Groundwater level maps
for surficial and deep zones at the inactive and active basins are provided as Figures 3-
1a through 3-2b. The saturated portion of the ash basins is superimposed on this unit.
Observations from the CSA indicate a distinct confining layer up to 25 feet thick,
attributed to the Black Creek Formation, beneath the active ash basin. However, our
interpretation is that this confining layer merges to the west with confining zones in the
upper portion of the Cape Fear Formation. The surficial deposits also include clay beds
up to 6 feet thick that likely act to impede vertical migration of constituents associated
with the ash basins.
Page 3-3
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
Inactive Basins
SynTerra
The Neuse River bounds the inactive basins on the east. Halfmile Branch bisects
the inactive basins and is likely to receive shallow groundwater from the areas of
the inactive basins along its channel.
In the area of the inactive basins, the upper portion of the surficial aquifer
usually consists of 4 to 8 feet of light gray to tan clay often with yellow to orange
mottling. These clays may often be sandy or contain gravel. They are interpreted
as alluvial deposits and often overlie layers of fine to medium to coarse sands
which may contain coarse, angular to subrounded quartz gravel. The ratio of
clay beds versus sandy to gravelly beds varies, but the overall thickness of the
surficial deposits is generally 10 to 18 feet.
The boundary between the surficial aquifer and Cape Fear Formation sediments
is sharp at times (IABMW-03S) and characterized by a transition from saturated
sands to tightly packed silts that may appear only damp to nearly dry in core
samples. Cape Fear material is generally compact and appears to impede
groundwater flow. A Shelby Tube collected at 20 to 22.5 feet in the boring for
IMW-01 BC yielded a vertical hydraulic conductivity result of 2.1 x 10-7 cm/sec.
Active Basin
Surficial deposits overlie Cape Fear sediments to the west of the active basin and
Black Creek sediments underneath the active basin and to the east (Geologic
Map, Figure 1-3).
From the active basin toward the east, the Black Creek Formation underlies the
surficial deposits. The distinct clay layer at the top of the Black Creek ranges
from 15 to 25 feet. It is a generally plastic, gray to dark gray to black, clay that
contains varying amounts of sand and silt. A Shelby Tube collected at 20 to 22.5
feet in the boring for AMW-06RBC yielded a vertical hydraulic conductivity
result of 4.2 x 10-8. In borings on the east side of the active ash basin (AMW-
6RBC, AMW-14BC, AMW-15BC), the distinctive clay unit is underlain by
interbedded, carbonaceous clays and sands of the Black Creek Formation.
Discontinuous bedrock outcrops are located in the vicinity of the site along
Beaverdam Creek and along the Neuse River between the inactive and active ash
basin areas. Observations to date indicate that surficial deposits and the
underlying Cretaceous sediments are the predominant hydrogeologic units at the
Page 3-4
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
site. Bedrock is not expected to play a significant role in the SCM or
groundwater modeling for the site.
3.3 Confining Layers
The surficial, the Black Creek and the Cape Fear aquifers as observed during soil boring
activities for the groundwater assessment all include layers that impede the vertical
migration of contaminants.
Surficial deposits underlying the Lee Plant consist of discontinuous layers of clay,
clayey sand and sands. The clay layers are laterally extensive at times especially in the
area of the inactive basins and the LOLA. They were often observed to be between 4 to
8 feet thick. A sample analyzed from surficial deposit clay underlying the LOLA at
LLMW-1S yielded a hydraulic conductivity of 9.5 x 10-8 cm/sec.
A regionally extensive confining unit, the Black Creek confining unit, was identified
underlying the active basin and areas to the east. As measured from soil borings, the
Black Creek confining layer ranges from 15 to 25 feet thick at the site. Cardinell and
Howe (1997) indicate the Black Creek confining unit averages 16 feet in thickness across
Wayne County. Analysis of a Shelby Tube sample collected from the Black Creek
(AMW-06RBC) at 20 to 22.5 feet bgs yielded a vertical hydraulic conductivity of
4.2 x 10-8 cm/sec.
Cape Fear sediments generally occur as clays and silts, or as sands in a clayey to silty
matrix. Other than a thin zone (< 10 feet) of sand just above the contact with bedrock,
tightly packed silts are the dominant lithology observed in Cape Fear sediments. A
Shelby Tube collected in Cape Fear sediment at 20 to 22.5 feet in the boring for IMW-01
BC yielded a vertical hydraulic conductivity of 2.1 x 10-7 cm/sec. The Cape Fear
Formation as observed at the site ranged from approximately 33 feet thick (AMW-11BC)
to greater than 82 feet (IMW-02BC).
3.4 Shelby Tube Analysis
As part of the 2015 CSA, Shelby Tube samples were collected at three locations in clayey
intervals in order to confirm confining characteristics of hydrogeologic units at the site.
A Shelby Tube collected at 20 to 22.5 feet in the boring for IMW-01 BC (Cape Fear)
yielded a vertical hydraulic conductivity result of 2.1 x 10-7 cm/sec (Table 3-1). A Shelby
Tube collected at 20 to 22.5 feet in the boring for AMW-06RBC (Black Creek) yielded a
vertical hydraulic conductivity result of 4.2 x 10-8 cm/sec. A sample analyzed from
surficial deposit clay underlying the LOLA an LLMW-1S yielded a hydraulic
conductivity of 9.5 x 10-8 cm/sec (Table 3-1).
Page 3-5
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
These data indicate that horizontal groundwater flow will predominate over downward
vertical flow at the site. Accordingly, lateral migration of dissolved CCR constituents
would be expected relative to vertical migration.
3.5 Site Hydrology
Groundwater at Lee is typically encountered at depths of 1 to 10 feet below ground
surface, depending on precipitation and topography. The surficial unconfined aquifer
is the first major hydrostratigraphic unit in all areas of the Lee site.
,61P Water levels were measured in selected wells, including historical and new
assessment wells, at the active and inactive basin areas over a 24-hour period in
June 2015. General observations from review of the groundwater elevation data
is summarized below.
101 As recognized in previous investigations and through compliance monitoring
activities, groundwater flow is toward the Neuse River (south for the active
basin, and east to southeast for the inactive basins and north for the LOLA).
47 Due to dike construction, grading and accumulation of ash to an elevation above
the surrounding land surface, a mound in the water table has developed under
the active ash basin. As a result of this mound, shallow groundwater flow is
radial away from the basin. However, groundwater gradients are north to south
within close proximity to the edge of the basin (no more than several hundred
feet).
01 Although the water table is mounded in the active basin, the resulting radial
flow from the basin returns to a natural north -south orientation with discharge to
the Neuse River.
47 Evidence of mounding of groundwater is only apparent in the northwest corner
of inactive basin 1. The gradient between IABMW-01S and BW-1 indicates
groundwater flow from southeast to northwest. However, this gradient is
expected to revert to the natural flow pattern toward the Neuse River within a
short distance (no more than several hundred feet).
3.5.1 Hydraulic Conductivity
In situ hydraulic conductivities for monitoring wells at the site were determined
by slug test method. Surficial deposits at the site consist of a range of material
from clays to coarse sands. The hydraulic conductivity for shallow wells
screened in sandy material range from 2.5 x 10-2 to 4.3 x 10-5 cm/sec. Wells
screened in the Black Creek Formation yielded slug test hydraulic conductivities
from 4.5 x 10-3 to 9.9 x 10-4cm/sec. Hydraulic conductivities in upper to middle
Page 3-6
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
intervals of the Cape Fear Formation wells ranged from 4.1 x 10-6 to 1.6 x 10-6
cm/sec (Table 3-2).
3.5.2 Hydraulic Gradients
Horizontal and vertical hydraulic gradients were calculated for the CSA based
on June 2015 groundwater levels. At the active basin horizontal hydraulic
gradients range from 0.001 to 0.021 ft per ft. At the inactive basins, horizontal
hydraulic gradients range from 0.005 to 0.013 ft per ft (Table 3-3). Groundwater
velocities for the active basin range from 3.1 to 277-feet per year. For the inactive
basins the range was from 0.4 to 158-feet per year.
Potential gradients were calculated for well pairs with appropriate screened
intervals in shallow and deep zones. Results indicate that there is generally
upward flow from deeper zones in areas along the Neuse River. This indicates
that groundwater is discharged to the river. Conversely, well pairs in
upgradient areas tend to show a weak downward gradient which indicates that
these are recharge zones (Table 3-4). Figure 3-3 shows a plan view of wells pairs
where gradients between shallow and deep zones were calculated. The figure is
color coded to indicate areas of recharge and discharge and intermediate areas.
3.5.3 Groundwater/Surface Water Interaction
The Neuse River and smaller surface water bodies are present near and at the
perimeters of the inactive and active basins (Figures 2-1a and 2-1b). Halfmile
Creek flows from northwest to southeast to join the Neuse River on the
downgradient (east) side of the inactive basins. It bisects the inactive basin area
and separates inactive basins 1 and 2 from inactive basin 3. Groundwater
discharges to Halfmile Creek and flows into the Neuse River. Perimeter ditches
have been installed at the toe of the basin dikes along the east and north sides of
the active basin. The ditches convey seepage from the bottom of the dikes, as
well as surface water from areas north of the basin, to discharge points on the
Neuse River west and east of the basin. Flow rates and gradients for surface
water were determined as part of the CSA and used in groundwater modeling.
Springs along the Neuse River south of the active basin also discharge
groundwater to the river (see Figures 2-1a and 2-1b for seep locations).
3.6 Site Geochemistry
This section contains geochemical information on the CCR constituents for the Lee
groundwater assessment. This information provides context for the data collected to
characterize the ash basin source areas and potential receptors.
Page 3-7
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex SynTerra
3.6.1 Source Characteristics
The three inactive ash basins, the active ash basin and the LOLA have historically
been used to manage CCR at the site. Despite one basin being referred to as the
active basin, none of the areas currently receive OCRs. The three inactive basins
have been inactive for several decades. Within a basin, water collects as either
free liquid above the ash or below the ash surface. When present below the ash
surface, it is referred to as ash pore water.
Pore water drains through the underlying soil to the groundwater or from
perimeter dams as seeps. Groundwater and seeps are the primary mechanisms
for migration of CCR constituents to the environment.
Ash pore water wells were installed in the inactive basins, the active basin and
the LOLA as part of CSA activities. Review of sampling results from ash pore
water wells lead to the following observations:
`7 Arsenic, barium, boron, cobalt, iron, manganese, thallium and vanadium are
ubiquitous in ash pore water, though not all occurrences are above the 2L or
IMAC. Provisional background concentrations greater than 2L have been
determined for cobalt, iron, manganese and vanadium.
161 Sulfate is the dominant sulfur species in pore water (sulfide was less than
detection levels that ranged from 0.1 µg/L to 10 µg/L). Sulfate is the
predominant anion in one ash pore water sample (PZ-3).
Bicarbonate is the dominant carbon species in pore water (carbonate was less
than 10 µg/L in all samples) and is the predominant anion in all but one ash
pore water sample.
161, Nickel was detected above the detection limit of 1 µg/L in 7 of 11 samples but
none of those exceeded the 2L of 100 µg/L.
01 Chromium was detected above the detection limit of 1 µg/L but below the 2L
of 10 µg/L in 1 of 11 samples.
01 Cobalt was detected above the detection limit of 1 µg/L in 7 of 11 samples, all
of which exceeded the IMAC of 1 µg/L.
3.6.1.1 CCR Constituents in Ash Pore Water
CCR constituents identified in conjunction with the Lee ash basins include
antimony, arsenic, barium, boron, cobalt, iron, manganese, thallium, TDS,
and vanadium. The majority of the ash pore water samples (11 samples at 8
locations) collected from the pore water wells and piezometers exceed the
Page 3-8
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
2L or IMAC for arsenic, boron, cobalt, iron, manganese, and vanadium.
Eight of the 11 samples fall within the pH 2L standard range of 6.5 to 8.5,
while three samples exhibited pH from 6.0 to 6.3. Additional exceedances
of a 21, or IMAC include antimony (three samples), selenium (one sample),
thallium (five samples), and TDS (five samples).
3.6.2 Groundwater
Groundwater sampling results evaluated in the CSA included historical and
recent compliance monitoring results, two rounds of sampling from 30 new
monitoring wells and a round of samples from 24 existing (non-compliance)
monitoring wells and piezometers (Table 1-2). Fourteen constituents were
detected in groundwater samples above a 2L or IMAC. Of the 14, cobalt, boron
(1 sample, BW-1), iron, manganese, vanadium were detected in background
wells. Provisional background concentrations are determined as part of the CAP
Part 1 for constituents that exceed 2L. Results are discussed in Section 2.0.
In addition, pH was observed outside of the 2L range of 6.5 to 8.5 in multiple
background wells. Most of these wells are located on the south side of the ash
basin and thus have elevated concentrations of CCR constituents as a result of
groundwater moving from the active basin toward the river.
3.6.2.1 Redox Conditions
For the most part, shallow monitoring well screens were set in soils that
exhibit oxidizing conditions such as reddish color. One well installed near a
wetland area (LLMW-2) was saturated to within a few feet of the surface
resulting in relatively reducing conditions. The lower Black Creek
Formation and Cape Fear Formation exhibited evidence of reducing
conditions that include gray color and strongly negative ORP readings in
groundwater.
Most wells installed in the surficial aquifer exhibited characteristics of an
oxidized environment; however, a few of the surficial wells did appear to
exhibit reducing conditions. Strongly reducing conditions were indicated in
ABMW-01S by a negative ORP, methanogenesis, and relatively high
concentrations of reduced arsenic, iron, and manganese present in
speciation samples.
3.6.2.2 Constituent Distribution in Groundwater
Cobalt, iron, manganese, and vanadium were detected in monitoring wells
across the site (Table 1-2). Boron, the most mobile of the CCR constituents,
Page 3-9
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
is detected above 2L in wells screened below ash at the inactive and active
basins, and in a limited number of wells in downgradient of the basins.
Inactive Basins
Exceedances of pH, cobalt, chromium, iron, manganese, TDS and vanadium
occurred in various locations around the inactive basins. The largest
number of 2L or IMAC exceedances occurred in samples from monitoring
well locations CW-01, BW-01 and SMW-3. Monitoring well CW-01 is
downgradient from inactive basin 3. Samples from CW-1 contained
chromium, cobalt, iron, manganese and TDS at levels above 2L or IMAC.
Monitoring well SMW-3 is located just north of inactive basin 2. Samples
from well SMW-3 contained pH, cobalt, iron, manganese and vanadium in
excess of the 2L or IMAC. Monitoring well BW-01 has historically been
considered a background well. However, based on the presence of boron
and the relative concentrations of iron and manganese BW-01 may be
impacted by localized radial flow from the inactive ash basins.
Active Basin
Exceedances of 2L or IMAC for pH, arsenic, cobalt, iron, manganese and
vanadium occurred in various locations around the inactive basins. Arsenic
appears to have migrated limited distances horizontally to the east from the
active ash basin. It has historically been detected in well CMW-6R which is
screened in surficial deposits. It has not been detected in well AMW-06RBC
which is located in the same area but is screened beneath the confining layer
in the Black Creek deposits. Iron is detected at elevated concentrations to
the west (CMW-7), south (CMW-10) and east of the active basin (AMW-
14S).
LOLA
For the two wells (LLMW-01S and LLMW-02S) installed in the surficial
aquifer in the LOLA area, constituent concentrations tended to be higher in
LLMW-02S than LLMW-01S. Exceedances of cobalt, iron, manganese, and
thallium were detected in LLMW-01S and exceedances of arsenic, barium,
cobalt, iron, manganese, and vanadium were reported in LLMW-02S. The
detection of thallium in LLMW-01S was only slightly above the method
detection limit which is equal to the 2L and was only detected in one of the
two sampling events for that well. The detection of vanadium above the
IMAC in LLMW-02S was only detected in one of the two sampling events.
Page 3-10
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex SynTerra
LLMW-02S was installed to the east of LLMW-01S, which is also the
direction of increasing wetness at the surface of the LOLA.
3.6.2.3 Facilitated (Colloidal) Transport
Facilitated transport is a phenomenon whereby a constituent may be
transported in groundwater more rapidly than expected based on idealized
Darcian flow and equilibrium sorptive interactions. One example of
facilitated transport is constituent sorption to colloids, small solid phase
particles or macromolecules (diameters less than 10 microns), and resulting
transport in the aqueous phase (Huling, 1989).
CSA and associated groundwater sampling activities to date have included
sampling and analysis for total and dissolved metals. The dissolved
fraction was determined by analysis of a sample volume passed through a
filter with 0.45 micron pore size. In order to determine whether colloidal
transport may be a significant factor in constituent migration, additional
groundwater samples were collected from representative monitoring wells
in September 2015 and passed through both a 0.45 micron filter and a 0.10
micron filter. Analytical results for this event are summarized on Table 3-5.
Laboratory analytical data is provided in Appendix B.
Review of the results indicates that arsenic, barium, boron, cobalt, copper,
manganese, nickel and strontium occur as soluble ions as evidenced by a
near 100% pass through the 0.1 micron filter. Aluminum, chromium,
vanadium, molybdenum and zinc showed some removal by filtration.
Based on results of the 0.45 micron and the 0.10 micron filtrates and
consideration of CCR constituents which exceed 2L at the site, colloidal
transport does not appear to be a significant factor in constituent migration.
3.6.2.4 Eh/pH/DO Diagrams
As part of groundwater monitoring activities, pH, oxidation/reduction
potential (redox or ORP) and dissolved oxygen (DO) were measured for
each monitoring well location. A system's ability to donate or receive
hydrogen ions is measured as pH. Redox is a measure of a system's ability
to donate or receive electrons. The standard by which redox is measured is
a hydrogen electrode. However, hydrogen gas is often not practical for use
in the field and other electrodes with a known potential compared to
hydrogen are used. Field measurements for redox are then converted to the
equivalent relative to the hydrogen electrode. The resulting term is (Eh).
Figures 3-4 through 3-20 illustrate Eh, pH and DO measurements at the site.
Page 3-11
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
SynTerra
Ash pore water values for Eh at the active basin range from 65 millivolts
(mV) to 429.3 mV. Ash pore water values for Eh at the LOLA range from
86.7 mV to 428 mV. Concentrations of CCR constituents in ash pore water,
particularly iron and manganese, appear to decrease with increasing Eh.
Measurements of pH in ash pore water do not vary significantly. DO values
for ash pore water are all less than 1.0 milligram per liter (mg/L).
Surficial groundwater values for Eh at the inactive basins range from 99 mV
to 410 mV and at the active basins from 50.1 mV to 498.1 mV. As with pore
water, higher constituent concentrations appear to correspond to lower Eh
values, however the trend is not as apparent for the inactive basins. DO
values for groundwater are generally low (<1.0 mg/L) for wells screened
beneath the basins, in deeper hydrostratigraphic units and in downgradient
areas. Well screened in shallow zones in upgradient areas tend to yield DO
values greater than 1.0 mg/L.
3.6.2.5 Time Versus Boron Concentration Diagrams
Compliance groundwater monitoring has been performed at Lee since 2010.
Time versus concentration diagrams for boron were reviewed for
compliance wells for both the active basin and inactive basins (Figures 3-
21a and 3-21b). A general seasonality of boron concentration is seen in
many of the wells on site. The diagrams for samples collected from wells
CMW-5, CMW-6R, and CMW-8 indicate pronounced seasonality. CMW-6R
is located downgradient of the ash basin on the east and CMW-5 and CMW-
8 are located between the ash basin and the Neuse River. All three wells are
located in low lying wet areas, indicating that a mechanism related to the
shallow water table is involved.
3.7 Correlation of Hydrogeologic and Geochemical Conditions to
Constituent Distribution
Based on results from the CSA and determination of provisional background
concentrations, the following groundwater constituents appear to be associated with the
presence of the ash management areas: arsenic, boron, cobalt, iron, lead, manganese,
sulfate, thallium and TDS. Impact from these constituents is focused on areas of
groundwater beneath the ash basins and in nearby downgradient areas. Migration of
CCR constituents in groundwater is inhibited by geochemical mechanisms such as
sorption to aquifer solids and precipitation in mineral phases. The degree of sorption is
measured by the distribution coefficient (Kd). Boron is relatively mobile in groundwater
and associated with low distribution coefficients. This is because boron is essentially
Page 3-12
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
inert, has limited potential for sorption and lacks an affinity to form complexes with
other ions. Geochemical mechanisms controlling the migration of CCR constituents are
discussed further in Section 4.0.
Due to the layout of the site with respect to the Neuse River, downgradient surface area
is limited in extent. Groundwater is expected to flow for short distances and discharge
to the Neuse River. Groundwater likely travels the greatest distance prior to discharge
to the Neuse River in downgradient to crossgradient areas east of the active basin.
Page 3-13
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
4.0 MODELING
SynTerra
A modeling program was conducted to evaluate the impact of various potential closure
options on groundwater and surface water quality. Modeling components included
groundwater fate and transport, geochemistry and supporting studies. SynTerra
partnered with specialists at Clemson University (Clemson) and the University of North
Carolina at Charlotte (UNCC) for this aspect of the CAP. Stand-alone reports from each
principal or organization are included in appendices and are summarized in this
section.
The modeling work, and associated analysis, included the following:
(1) Determination of the ability of on -site soil to sorb dissolved constituents derived
by the leaching of ash. The degree of sorption is measured by the distribution
coefficient, and was determined by conducting batch and column studies on
numerous soil samples collected in key hydrostratigraphic units. The
distribution coefficient is a key factor in the numerical flow and transport model.
(2) Assessment of various retardation processes (processes that lessen the dissolved
concentration and reduce the velocity of constituent movement) to determine
which are most likely occurring and the likelihood that the process will continue
after site closure.
(3) Development of numeric fate and transport model to predict the configuration of
groundwater flow once a closure plan has been implemented. After the flow
model was calibrated, a groundwater quality model was developed to predict
groundwater quality conditions once closure is implemented.
(4) Development of a model to predict constituent concentrations in major receiving
surface water bodies in the area of the site.
4.1 Determination of Distribution Coefficient
An important aspect of determining the movement of metals in groundwater is
information about the ability of the soil to retain a portion of the dissolved constituent
on the soils surface. Generally, the retention is either through sorption or precipitation.
Sorption occurs when the dissolved constituent comes in contact with a soil particle and
is retained by the particle until it is released and adheres to the adjacent particle. In
order to quantify this variable the amount of a constituent dissolved in water and the
amount of a constituent adhering to soil must be known. These measurements are often
made in a laboratory setting. These studies result in the calculation of the distribution
Page 4-1
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
coefficient - Kd. SynTerra retained UNCC to determine site specific distribution
coefficients (Kd) for the primary hydrostratigraphic units. The UNCC final report is
included as Appendix C.
Six soil samples were collected for testing. One portion of a sample was placed in large
mouth bottles for batch analysis, and a second portion of the sample was packed into
columns for testing. A solution of groundwater was prepared for the batch and column
procedures. Test procedures followed USEPA protocol where applicable. Results from
the studies are presented on Table 4-1.
Page 4-2
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
Table 4-1
Summary of Distribution Coefficients
SynTerra
Lee Batch Results
Sample Location/Parameter
Arsenic
Boron
Barium
Cobalt
Antimon
Selenium
Thallium
Vanadium
ABMW - 15B (36 - 40 ft.)
Trial 1
40.5
21.7
32.3
18.1
59.2
Trial
38.6
-
20.1
35.3
-
ABMW - 15B (46-47.5ft.)
Trial 1
294.0
171.8
177.4
135.6
177.6
Trial
306.0
158.9
176.7
136.3
223.2
AMW - 09 (16 - 18 ft.)
Trial 1
891.4
1418.2
101.0
275.4
209.4
801.5
Trial
695.1
1
1032.6
94.8
198.3
188.0
295.6
AMW - 14 (20.5 - 22.5 ft.)
Trial 1
14.8
9.6
20.7
35.7
Trial
14.0
8.5
20.1
30.3
AMW - 15 (17 - 19 ft.)
Trial 1
599.8
3.8
689.6
301.7
163.9
644.1
109.8
Trial
597.3
3.5
535.8
289.9
1 159.2
625.6
118.3
IABMW - 3 (20 - 23 ft.)
Trial 1
322.2
83.8
76.4
716.1
175.3
Trial
382.8
64.0
67.8
971.3
254.9
Geometric Mean
175
4
22
858
Al
Off 69
139
138
Median
314
4
22
861
130
118
162
175
Lower Quartile Exclusive
39
5741
87
23
24
59
Column Results
ABMW - 15B (36 - 40 ft.)
275
450
575
775
175
225
600
ABMW - 15B (46 - 47.5 ft.)
200
850
700
650
400
750
700
AMW - 09 (16 - 18 ft.)
300
225
425
1100
200
100
750
AMW - 14 (20.5 - 22.5 ft.)
Trial A
80
25
150
120
40
40
125
125
Trial B
75
175
150
40
40
175
150
Trial C
70
30
150
125
30
40
120
125
AMW - 15 (17 - 19 ft.)
150
100
600
725
225
525
350
IABMW - 3 (20 - 23 ft.)
950
925
1050
1150
950
525
--
Geometric Mean
178
42
316
353
262
145
243
307
Median
175
30
225
500
688
188
200
350
Lower Quartile Exclusive
76
25
150
1 131
1 40
1 40
121
125
The samples from ABMW -15B are logged as SP (sand) [surficial unit], whereas the
other samples are logged as SP, SM and ML (silty sand to silt) [Black Creek or the
confining unit]. Except for AWM -14, the finer grained soils have greater values of Kd.
The sample from AWM -14 is in a transition zone between sand and silt.
4.2 Geochemical Modeling
A geochemical model was developed by Dr. Brian Powell as part of the CAP to
characterize the current geochemical conditions in and around the Lee ash basins
(Appendix D). The geochemical model was used to provide an analysis of corrective
action alternatives, including Tiers II and III of the MNA analysis to be provided in the
CAP Part 2. The model simulates chemical reactions between the groundwater, CCR,
and other porous media (i.e., constructed and natural subsurface).
Page 4-3
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
The key conclusions of the geochemical model are:
'67 Modeled Kd values generally align with those determined experimentally by
Langley et al. (2015) and those used in the fate and transport model,
'67 There is a low probability of the aquifers to reach their capacity to sorb
(attenuate) the constituents of interest,
167 pH and oxidation/reduction potential (Eh) have a fundamental influence on the
extent of partitioning in pore water at HF Lee Energy Complex.
The conclusions were determined through the development of this model in four steps
that together depict potential mechanisms and geochemical processes at work:
Ej Eh -pH diagrams showing potential stable chemical phases of the aqueous
electrochemical system, calibrated to encompass conditions at the site.
Ej Correlation analysis where observations from groundwater measurements are
plotted and interpreted, to identify important features of the geochemical
system.
167 Sorption model where the aqueous speciation and surface complexations are
modeled using the USGS geochemical modeling program PHREEQC.
47 Attenuation calculations where the potential capacity of aquifer solids to
sequester constituents of interest were estimated.
The Eh -pH diagrams and correlation analysis of field data indicated important details
about the potential mobility of constituents at the site including the following:
l� Dissolved oxygen appears to be the dominant redox buffer below pH 6.
j� Arsenic, selenium, and vanadium exhibit widely varying sorption behavior
primarily related to the change in their sorption affinity at each oxidation state.
j� Ba, Zn, Co, and Pb are present predominately as divalent cations whose sorption
increases with increasing pH.
�1 Borate ions are essentially inert, exhibiting minimal sorption affinity and are
therefore relatively mobile and soluble.
The sorption model was designed to evaluate ion sorption to HFO using a diffuse
double layer model developed by Dzomback and Morel, 1990. Sorption model
simulations include site specific Eh and pH values and assumptions made in the
Langley et al. (2015) site report. Modeled Kd values calculated from the minimum and
Page 4-4
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex
SynTerra
maximum pH and/or EH values, as well as, the averaged Kd values from Langley et al.
(2015) are presented in Appendix D (Powell, 2015). Except for barium and borate,
experimental data are generally captured by the minimum and maximum model
predicted Kd values. It is important to note that there are many factors that play a role
in the sorption/desorption of constituents with porous media that were not directly
addressed in this model. Incorporating additional functions into a geochemical model
does not necessarily translate to an increased confidence in the results. Both mineralogy
and organic carbon are known to affect Kd values in a variety of ways, but were not
directly addressed in this model. Organic carbon influence on sorption is highly
variable, and given the heterogeneity at the site, incorporating organic carbon into the
model would not add meaningful confidence to the predictive results. The
mineralogical data at the site indicated minute quantities of transition metal minerals
that would influence the Kd values, and was addressed in this model by using Eh as a
proxy for reducing conditions to account for the potential for reduced forms of minerals
with influence, such as sulfides.
The attenuation capacity was calculated to determine the affinity of the aquifer
materials to retain constituents in the solid phase. Calculations were performed using
site specific data derived from the fate and transport model, the Langley et al. (2015)
report, and the NC21, groundwater standard concentrations. Results indicated that HFO
sorption sites could sorb all available constituents of interest and would not reach
capacity until approximately 400 times the NC2L standards. It is important to note that
the calculation assumes 100% sorption, which will not be the case for all constituents,
and that while the data reveals it is unlikely that the capacity of the aquifer solids
would be exceeded, the results can vary based on the Kd for each constituent and
specific geochemical conditions.
4.3 Numerical Fate and Transport Model
The purpose of this study is to predict the groundwater flow and constituent transport
that will occur as a result of different possible corrective actions at the site. The study
consisted of three activities:
01 Development of a calibrated steady-state flow model of current conditions,
Development of a historical transient model of constituent transport that is
calibrated to current conditions, and
47 Predictive simulations of the different corrective action options.
Three major elements for the development of the groundwater flow and transport
model are summarized below:
Page 4-5
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
The site conceptual model for the groundwater model was based on the model
presented in the CSA. No significant changes had to be made in the SCM in
order to calibrate the flow and transport model.
The numerical flow model was developed using MODFLOW and the transport
model was developed using MT3DMS. MODFLOW is based on Darcy's law and
MT3DMS uses the groundwater flow field from MODFLOW to simulate 3D
advection and dispersion of the dissolved constituents including the effects of
retardation due to constituent adsorption to the soil matrix.
101 Key transport model parameters are the constituent source concentration in the
ash basin and the distribution coefficients (Kd) calculated by Langley et al. (2015).
Source concentrations were taken from ash pore water concentrations obtained
from the field and were applied throughout the ash basin as specific
concentrations. It was also decided to take the conservative approach and to
initially use a low Kd value for each constituent in the model, even though the
observed Kd values are highly variable throughout the site. The initial value
used in calibration was the minimum measured value from Langley et al. (2015).
Once calibrated, a uniform Kd value is used throughout the model for each
modelled constituent.
Excerpts from the Groundwater Flow and Transport Modeling Report for H.F. Lee Energy
Complex (Brame, et. al., 2015) are italicized below. Figure and table references are
retained from the original document and included in Appendix E.
4.3.1 Flow and Transport Model
The flow and transport model for this site was built through a series of steps. The first
step was to build a 3D model of the site hydrostratigraphy based on field data. The next
step was determination of the model domain and construction of the numerical grid. The
numerical grid was then populated with flow parameters which were adjusted during the
steady-state flow model calibration process. Once the flow model was calibrated, the flow
parameters were used to develop a transient model of the historical flow patterns at the
site. The historical flow model was then used to provide the time -dependent flow field for
the constituent transport simulations.
4.3.1.1 Flow Model
The steady state flow model calibration targets used 40 water level
measurements made in observations wells in June, 2015. The correlation
between observed and calculated head measurements for current conditions
is shown in Figure 4-1.
Page 4-6
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
5
E
U
82
80
78
76
74
72
70
68
66
64
62
60
Computed vs. Observed Values
Head
60 65 70 75 80
Observed
SynTerra
Figure 4-1 Comparison of observed and computed heads from the calibrated steady state
flow model.
4.3.1.2 Transport Model
The transient flow model uses a simplified approximation of this complex
history that simulates the basin as having a constant footprint over time,
equal to its shape since 1952. The basin infiltration rate during sluicing is
not known, but it was estimated by taking the results of the calibrated
steady state flow model and adjusting the infiltration rate until parts of the
basin are flooded. This resulted in an estimate of the infiltration rate during
sluicing ranged from 11.8 to 49.9 in/yr.
The transient flow field was modeled as four successive steady state flow
fields; one corresponding to the high infiltration rate during ash sluicing
from 1952 to 1968 in the north in -active ash basin; one corresponding to the
high infiltration rate during ash sluicing from 1995 to 1978 in the in -active
ash basin; one corresponding to the high infiltration rate during ash sluicing
from 1978 to 2012 in the active ash basin; and one corresponding to the
current basin infiltration rate from 2011 to 2015.
The transport model calibration targets are constituent concentrations
measured in 44 monitoring wells in June, 2015 (SynTerra, 2015). The
Page 4-7
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
constituents modeled were selected based on significant concentrations in
ash pore water greater than likely background levels and whether there was
a discernible plume of the constituent extending downgradient from the ash
basin. The major focus of the concentration matching effort was devoted to
arsenic, boron, iron, and manganese in and around the ash basin. Boron
was chosen as the main tracer for the ash basin for three main reasons: 1)
boron is always present in coal ash 2) there is typically a low background of
boron concentrations 3) boron is the most mobile constituent. The
correlation between observed and calculated boron concentration
measurements for current conditions are shown in Appendix E.
Based on review of the calibration results for iron and manganese there is
potential for historical CCR constituent migration for short distances north
of the inactive basins. Proper abandonment of water supply wells and
access to public water pipelines will be evaluated for parcels between the
inactive basins and Old Smithfield Road. The associated parcel IDs are
provided in Table 4-2.
4.3.2 Model Results
Once the flow model was calibrated with regard to water levels, and the
simulated arsenic and boron concentrations in wells around the active basin
closely matched observed concentrations that exceeded the 2L standards, the
model was used to predict contaminant distributions for the next 5, 15, and 30
years. The dates for those simulations are referred to in the model report as 2020,
2030, and 2045 respectively. With regard to the corrective actions modeled, it
was assumed that they had been completed by July 2015.
The following typical closure scenarios were modeled to illustrate the model's
functional capability:
1. Existing conditions for the ash basins.
2. Cap the ash basins with a low permeability cover.
3. Ash removal and transport to off -site lined structural fill.
In the existing conditions simulation, CCR constituent impact gradually
diminishes as recharge from upland areas dilutes groundwater and pushes
constituents toward the Neuse River. The extent of arsenic and boron to the east
of the active basin does not increase significantly. The farthest extent of the
Page 4-8
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
impact is controlled by the presence of the Neuse River. Figures 18 through 30 in
Appendix E display the results of the existing conditions scenario for the years
2020, 2030, and 2045.
The low permeability cap scenario involves placing a cap or cover over the ash
basin to contain the ash and to prevent rainwater infiltration. This scenario
assumes that there is no recharge within the ash basin and but maintains
constituent concentration levels. The extent of the boron plume reduces over
time since because recharge to the basins has been removed. Figures 101 to 112
in Appendix E display the results of this scenario for the years 2020, 2030, and
2045.
The ash removal scenario includes full excavation of the ash basins and
subsequent re -grading to match surrounding areas. This scenario assumes that
there is no longer a constant source of contaminants. This simulation shows a
reduction of boron in the upper surficial zone. Figures 43 through 54 in
Appendix E display the results of the ash basin excavation scenario for the years
2020, 2030, and 2045.
Future fate and transport modeling results will be considered in the corrective
action evaluation and recommendation process detailed in the CAP Part 2.
4.4 Groundwater and Surface Water Interactions
4.4.1 Flow Considerations
Determining the impact as groundwater discharges into a surface water body is
predicated on knowing low flow values for the surface water body and the
amount of groundwater discharging into the surface water body. Based on these
data and using a mass balance equation, concentrations of analytes can be
calculated for a location downgradient of the discharge area. A conceptual model
illustrating groundwater discharge to a surface water body is provided as Figure
4-2. Low flow measurements exist for major river systems. For example, the
United States Geological Survey has established long term flow monitoring
stations on major rivers and streams in North Carolina. Typically these stations
have several flow statistics representing various conditions, which are available
on the web. Also, USGS has published numerous reports summarizing low flow
statistics. NCDEQ has a website which posts the 7Q10 values (a common low
flow measurement) for any facility having a NPDES permit. All of these sources
were examined as part of this analysis. The 7Q10 for the Lee facility is 263 cubic
feet per second (cfs).
Page 4-9
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Once these factors are known (or estimated) then it is possible to calculate
concentrations of constituents in the surface water body, and then to compare
these estimates to measured values.
The basic equation for calculating a dilution factor, Df, resulting from a point
discharge (pipe) or a non -point discharge, like groundwater flow, is
1. Df = (Flow in River + Flow in groundwater)/Flow in groundwater
When calculating dilution a low flow value is preferred, in most cases the 7Q10 if
available, and if not a similar statistic. In some cases this flow may be multiplied
by a factor of safety so that the discharge does not use all the assimilative
capacity in that stretch of the river. A typical factor of safety is 0.8 to 0.9. Using a
low flow value and a safety factor results in a conservative estimate of flow in the
Neuse River. By using a conservative estimate of flow, the calculated
concentration of a constituent is also conservative.
Groundwater flow is calculated by using variations of Darcy's Law. Freeze and
Witherspoon (1967) describe the likely groundwater flow patterns from
highlands to a major discharge area. Based on the geologic characterization
conducted in the CSA, Darcy's Law applies to the Site.
The formula for calculating the volume of flow discharging to the river is
1. Qgw = KiA
Where:
Qg,N = Quantity of groundwater flow
K= horizontal hydraulic conductivity (1/t)
i = hydraulic gradient (1/1)
A = Cross sectional area)
The dilution factor is:
1. Df = (QLFV X 0.9)/Qgw
where:
QLFV = Low Flow Value (3/t)
0.9 = Safety Factor (unit less)
Page 4-10
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
This formula assumes instantaneous mixing with flow in the entire river. While
this may not be entirely valid for a point discharge it is more valid for
groundwater discharge because the discharge occurs over a large area. This
broad area assures a more uniform and faster mixing of the waters when
compared to a point discharge.
4.4.2 Concentration of a Constituent
Once the dilution factor has been calculated then it can be applied to the
concentrations in the Neuse River.
The flux of a constituent passing through a plane of the river (perpendicular to
the flow direction) at a point upgradient of the groundwater plume is:
1. Fluxup = QLFV x c
where:
Fluxup = flux of a constituent at the upgradient side of the
groundwater plume (m/t)
c = concentration of the constituent (mass/L3)
The flux of a constituent in groundwater discharging into the surface water body
is:
1. Fluxc = Qgw x c
In order to calculate the concentration of a constituent at a point in the surface
water body beyond the end of the groundwater plume the following mass
balance formula is used.
1. Cdown = (Cup X QLFV + Cgw X Qgw)/(QLFV + Qgw)
4.4.3 Results
The Lee Plant maintains a NPDES permit for three discharge locations along the
Neuse River. The NPDES permit is based on a 7Q10 low flow value for the Neuse
River of 273 cfs (DEQ NPDES spread sheet available at
http://Vortal.ncdenr.org/web/wq/swp/12s/npdes/calc/ol2tionl
The dominant groundwater flow regime at Lee is through coastal plain
sedimentary deposits. This environment is appropriate for application of Darcy's
Law. Therefore, it can be assumed that all groundwater flow (Qgw) in the
sedimentary deposits discharges to the river. At the active basin the width of
affected groundwater between the Site and the Neuse River is approximately
Page 4-11
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
5000 feet with an average thickness of 35 feet. The horizontal gradient at this
point is 0.011 and the geometric mean of the hydraulic conductivity is 4.9 feet per
day. Thus, there is approximately 9400 cubic feet per day or 0.11 cubic feet per
second. Thus the dilution factor, based on flow, is approximately 2,150 times
(this includes a factor of safety of 10 percent).
A limited amount of water quality data is available from the Neuse River. The
upstream sample location is S-16, which has been sampled on two occasions in
2014 and 2015; S-10 is located between the inactive and active basins and has
been sampled three times in 2014 and 2015; S-11 and ASW-NR1 are downstream
samples and each has been sampled one time in 2014 (S-11) and 2015 (ASW-
NR1). Table 4-2 shows the water quality data of these stations.
There is insufficient data to make statistical comparisons between the stations.
Inspection of the results indicates no observable differences between the stations.
This finding is in keeping with the dilution calculation.
4.4.4 Sensitivity Analysis
The flow of the Neuse River has the greatest impact on the concentration of a
constituent. This is because the flow in the river is much greater than the
discharge of groundwater (by a factor of 2,150 times under low flow conditions.
As a 7Q10 flow seldom occurs, the actual dilution factor is larger than that
calculated and often significantly greater. Two other factors are the ratio of the
concentration in groundwater to that in surface water, since the concentration in
groundwater is apt to be larger than surface water, and the volume of
groundwater discharging to the river. The other factors described above have a
minor impact on the final result. The following calculations show the effect of
varying select factors.
If the flow in the river is assumed to be at the 1st quartile, instead of the 7Q10,
the flow rate increases to 733 cfs (so the dilution factor rises by 2.5 times); if the
median value is used (1020 cfs) then the dilution factor is increased by 3.7 times.
Water quality results from compliance wells between the active basin and the
river (e.g., CMW-5, CMW-8, and CMW-10) don't reveal a trend over the period of
record (2010 — 2015). Thus, the mass of the constituent loading to the Neuse has
not significantly changed over the past five years. The last significant factor is
the volume of groundwater discharging into the Neuse River. Hydraulic
conductivity has the greatest variation of the factors involved in the calculation.
Hydraulic conductivity is apt to vary by 5 to 10 times over an area the size of the
Page 4-12
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
Lee Plant and within the units discharging to the river, which can have a large
impact on the flux of groundwater but a small impact on dilution.
Page 4-13
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
5.0 CORRECTIVE ACTION PLAN PART 2
A risk assessment, evaluation of potential remedial alternatives and the recommended
remedial approach will be provided in the CAP Part 2. Information presented in this
CAP Part 1 document that is relevant to the Part 2 report is summarized in the
following paragraphs.
The Lee CSA combined with groundwater fate and transport modeling and
geochemical modeling shows that boron is the key constituent for determining
influence on groundwater quality. Migration of boron in groundwater east of the active
basin will be evaluated for corrective action based on results of the risk assessment.
Groundwater modeling indicates that boron, as well as arsenic, impact to groundwater
may extend beyond the compliance boundary on the east side of the active basin.
Groundwater modeling also indicates that iron and manganese impact may extend
beyond the compliance boundary to the south of the inactive basins. Additional
monitoring well locations are being evaluated to assess these areas, as well as to bolster
the existing network of background monitoring wells.
Provisional background values have been established for key parameters. Constituents
in groundwater whose background concentrations exceed 2L or IMAC include
antimony, arsenic, boron, cobalt, iron, manganese, sulfate, thallium, TDS and
vanadium.
A tentative plan for addressing groundwater exceedances has been developed. The
plan includes the following elements.
1) Duke Energy has recommended the removal of ash from the plant site with
placement in the former Colon clay mine.
2) Monitored natural attenuation MNA will be fully evaluated as a potential
groundwater remedy for areas of the site. A groundwater and surface water
quality sampling plan will be developed to track the concentration of key
constituents against projections in the fate and transport model and in the
geochemical model.
3) Other closure options which may be considered include phytoremediation, a
collection trench and groundwater extraction. Enhanced phytoremediation
involves the uptake of contaminants by plants. Simply stated, return of boron
released to groundwater by the combustion of fossil biomass (coal) to biomass at
the surface of the earth would restore the cycle of boron as a micronutrient.
Page 5-1
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
Groundwater restoration by installation of a collection trench or extraction may
also be evaluated with groundwater modeling in the CAP Part 2.
Analytical data summarized in this CAP Part 1 make it clear that the chemistry of
groundwater, surface water, and soil varies with the localized environment from which
the sample was collected. A geochemical model has been developed to help interpret
the chemistry of the surficial soil environment. The model identifies the likely
attenuation reactions occurring in the subsurface environment and calculations based
on the model indicate that the reservoir of attenuation potential remains extensive.
These findings support the plan described above.
Note that Duke Energy's recommendation to excavate is still subject to the outcome of
the NC CAMA risk ranking process where NCDEQ will recommend a risk ranking for
each ash basin by late 2015, and then the Coal Ash Management Commission will
follow with a final decision. Sites with high or intermediate risk rankings will require
excavation under NC CAMA. In addition, Closure Plans for each ash basin are now
under development by Duke Energy as required by both the EPA CCR Rule and NC
CAMA. These Closure Plans are expected to refer to the associated CAP Part 2
conclusions and proposed corrective actions in support of the recommended closure
approach.
Page 5-2
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1 November 2015
H.F. Lee Energy Complex SynTerra
6.0 REFERENCES
ASTM D6312-98: Standard Guide for Developing Appropriate Statistical Approaches
for Groundwater Detection Monitoring Programs. 2012.
David A. Dzombak, Francois M.M. Morel, Surface Complexation Modeling, Hydrous
Ferric Oxide, 1990
Electrical Power Research Institute (EPRI), Monitored Natural Attenuation for Inorganic
Constituents in Coal Combustion Residuals. August 2015
Griffith, G.E., Omernik, J.M., Comstock, J.A., Schafale, M.P., McNab, W.H., Lenat, D.R.,
MacPherson, T.F., Glover, J.B., and Shelburne, V.B. 2002. Ecoregions of North
Carolina and South Carolina, (color poster with map, descriptive text, summary
tables, and photographs): Reston, Virginia, U.S. Geological Survey (map scale
1:1,500,000).
Brame, S. E., Graziano, R., Falta, R. W., Murdoch, L.C. Groundwater Flow and Transport
Modeling Report for H.F. Lee Energy Complex. 2015.
Geosyntec Consultants. Preliminary Site Investigation Data Report, Conceptual Closure Plan,
H.F. Lee Plant. November 2013a.
Geosyntec Consultants. Data Interpretation and Analysis Report — Conceptual Closure Plan —
H.F. Lee Plant. December 2013b.
Geosyntec Consultants. Letter Report — Stage I Work — Response to Third Party
Recommendations for Ash Pond Dikes. August 26, 2014.
Langley, W.G., Oza, S., Soil Sorption Evaluation H.F. Lee Steam Station. UNC Charlotte,
NC. 2015.
NCDENR. Classifications and Water Quality Standards Applicable to the
Groundwaters of North Carolina. North Carolina Administrative Code Title 15A,
Subchapter 02L. 2013.
NCDENR. North Carolina Administrative Code Title 15A, Subchapter 02B.
Classifications and Water Quality Standards Applicable to the Surface Waters of
North Carolina. 2013.
Page 6-1
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
NCDENR. North Carolina Administrative Code Title 15A, Subchapter 02L.
Classifications and Water Quality Standards Applicable to the Groundwaters of
North Carolina. 2013.
NCDENR. Classifications and Water Quality Standards Applicable to the Surface
Waters of North Carolina (Pending EPA Approval of 2007-2014 Triennial
Review). North Carolina Administrative Code Title 15A, Subchapter 02B. 2015.
Niswonger, R.G.,S. Panday, and I. Motomu, 2011, MODFLOW-NWT, A Newton
formulation for MODFLOW-2005, U.S. Geological Survey Techniques and
Methods 6-A37, 44-.
North Carolina Department of Natural Resources and Community Development.
Geologic Map of North Carolina. 1985.
Powell, B., Analysis of Geochemical Phenomena Controlling Mobility of Ions from Coal Ash
Basins at the Duke Energy H.F. Lee Energy Complex. Pendleton, SC. 2015.
SynTerra. Comprehensive Site Assessment Report. August 5, 2015
USEPA. Risk Assessment Guidance for Superfund Volume 1, Human Health
Evaluation Manual, (Part A). EPA / 540 / 1-89/002;1989.
USEPA. Guidelines for Ecological Risk Assessment. 1998.
USEPA. Study of Hazardous Air Pollutant Emissions from Electric Utility Steam Generating
Units - Final Report to Congress, v. 1. Office of Air Quality, Planning and
Standards. Research Triangle Park, NC 27711, EPA-453/R-98-004a;1998.
USEPA. Report to Congress Wastes from the Combustion of Fossil Fuels, Methods, Findings,
and Recommendations, v. 2. 1998.
USEPA. Region 4 Ecological Risk Assessment Bulletins —Supplement to RAGS. 2001
USEPA. Monitored Natural Attenuation of Inorganic Contaminants in Ground Water —
Volume 1, Technical Basis for Assessment, EPA/600/R-07/139. October 2007.
USEPA. National Recommended Water Quality Criteria. 2009.
USEPA. Ecological Soil Screening Levels; 2015.
USEPA. Region 4 Recommended Ecological Screening Values — Soil.
Page 6-2
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
SynTerra
http://www.epa. gov/region4/superfund/images/allprogrammedia/pdfs/tsstableso
ilvalues.pdf.2015
USEPA, Scott G. Huling, Superfund Ground Water Issue, Facilitated Transport, EPA / 540 /
4-89/003;1989.
Zheng, C. and P.P. Wang, 1999, MT3DMS: A Modular Three -Dimensional Multi -
Species Model for Simulation of Advection, Dispersion and Chemical Reactions
of Contaminants in Groundwater Systems: Documentation and User's Guide,
SERDP-99-1, U.S. Army Engineer Research and Development Center, Vicksburg,
MS.
Page 6-3
P:\Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
Figures
SynTerra
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL\ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
Tables
SynTerra
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan\ CAP Report\ FINAL\ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
APPENDIX A
SynTerra
DUKE ENERGY BACKGROUND PRIVATE WELL
SAMPLING
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
APPENDIX B
SynTerra
LABORATORY RESULTS - 0.1 MICRON FILTERED
GROUNDWATER
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
APPENDIX C
SOIL SORPTION EVALUATION
H. F. LEE ENERGY COMPLEX
SynTerra
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
APPENDIX D
SynTerra
ANALYSIS OF GEOCHEMICAL PHENOMENA
CONTROLLING MOBILITY OF IONS FROM COAL
ASH BASINS AT THE DUKE ENERGY
H. F. LEE ENERGY COMPLEX
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx

Corrective Action Plan Part 1
November 2015
H.F. Lee Energy Complex
APPENDIX E
GROUNDWATER FLOW AND TRANSPORT
MODELING REPORT FOR
H. F. LEE ENERGY COMPLEX
SynTerra
P: \ Duke Energy Progress.1026 \ 104. Lee Ash Basin GW Assessment\ 16.Corrective Action Plan \ CAP Report \ FINAL \ FINAL
HF Lee CAP 11-02-2015.docx