NC0003425_Rox_Appendix M_20191231

Corrective Action Plan Update December 2019
Roxboro Steam Electric Plant
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V
REMEDIATION ALTERNATIVE SUMMARY
SynTerra

Remediation Alternatives
Remediation Alternative 1
Monitored Natural
Attenuation
Monitored Natural Attenuation
(MNA) relies on natural
attenuation mechanisms to
reduce COI concentrations over
time to meet corrective action
goals. For inorganics, these
processes include adsorption to
soil and bedrock surfaces,
precipitation, ion exchange,
phyto-attenuation, dilution and
dispersion.
Q
o!
A. Human Health & Environment
Human Health
There is no measurable difference between evaluated Site
risk and risk indicated by background concentrations;
therefore, no material increase in risks to human health
related to the ash basins have been identified. The
assessment conservatively included potential recreational
receptors in Hyco Reservoir. Human receptors are not
affected by groundwater from the Site as water supply wells
are located upgradient or outside the drainage basin.
Furthermore, 80 water supply wells within the 0.5-mile radius
of the ash basin compliance boundaries have had water
filtration systems installed.
Environment
The Roxboro ash basins do not cause an increase in risks to
ecological receptors (mallard duck, great blue heron,
muskrat, river otter, bald eagle, American robin, meadow
vole, red-tailed hawk, red fox and killdeer bird) evaluated for
the Hyco Reservoir exposure area, based on the results of an
ecological risk assessment performed for the Roxboro ash
basins using USEPA guidance (see Appendix E).
APPENDIX M, TABLE 1
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 1
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
B. Compliance with Applicable Regulations
Federal
MNA complies with USEPA CCR Rule specified in 40 Code
of Federal Regulations (CFR) § 257.
State
MNA will comply with Coal Ash Management Act of 2014
and 15A NCAC 02L .0106(I). If approved and subject to
notification requirements including the NC Department of
Transportation and NCDEQ for Sediment and Erosion
Control associated with monitoring well installation for
effectiveness monitoring. For additional details on MNA
see Appendix I.
Local
MNA would be subject to notification requirements to any
affected parties and to Person County officials per 15A
NCAC 02L .0114(b).
C. Technical & Logistical Feasibility
Ability to construct and operate technology
There are 172 monitoring wells already installed related to the
ash basins. Other than abandonment of selected wells for basin
closure and potential installation of additional monitoring wells,
no significant construction is required for implementation.
Reliability of technology
MNA has been used successfully to achieve remedial objectives
for a wide range of COIs and geologic settings either as a stand
alone remedy, or in combination with other remediation
approaches. The CSM supports the reliability of an MNA
approach.
Ease of undertaking additional RAs if necessary
Other remedial technologies have commonly been used in
conjunction with MNA. Use of MNA will not adversely impact the
implementation of other potential remedial actions.
Ability to monitor effectiveness of remedy
Effectiveness is monitored through evaluation of COI
concentrations over time in accordance with a groundwater
effectiveness monitoring program.
Ability to coordinate and obtain approvals from
other agencies
MNA does not require interaction with other agencies to
implement.
Availability of services and materials
An extensive groundwater monitoring well network already
exists. Additional monitoring wells may be required to
complete the MNA well network. All services and materials are
readily available to support effectiveness monitoring.
D. Time Required to Initiate and Implement
Requirements for bench scale testing
There are no requirements for bench scale testing to implement
MNA.
Design
MNA is readily implementable. The existing monitoring well
network can be utilized to design the MNA network.
Permitting
Soil Erosion and Sediment Control permits are required for any
land disturbance, including well installation activities. These
permits are a straightforward to procure.
Page 1 of 6

Remediation Alternatives
Remediation Alternative I
Monitored Natural
Attenuation
Monitored Natural Attenuation
(MNA) relies on natural
attenuation mechanisms to
reduce COI concentrations over
time to meet corrective action
goals. For inorganics, these
processes include adsorption to
soil and bedrock surfaces,
precipitation, ion exchange,
phyto-attenuation, dilution and
dispersion.
Q
E. Short-term Effectiveness
Protection of Community
The surrounding community would not be affected during
implementation of MNA activities performed on Duke Energy
property. Any increase in traffic on roads leading to Roxboro
due to the nature of the work would be de minimis.
Worker Protection
Work would be performed under a Health & Safety Plan, which
identifies risks and mitigation measures to protect workers and
the environment. All personal will be require relevant training
and supporting documentation to verify competency.
Environmental Impacts
There would be some migration of COI affected groundwater
would be expected as part of the attenuation process.
However, human health and ecological risk assessments do not
indicate significant risks.
Time Until Action is Complete
Predictive groundwater modeling indicates compliance to
regulatory standards at the compliance boundary in
approximately 700 years following basin closure.
APPENDIX M, TABLE 1
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 1
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
F. Long-term Effectiveness
Adequacy and Reliability of Controls
Implementation and maintenance of an effectiveness monitoring
program will be in place to evaluate variations from expected
conditions. Alternative measures can be taken to address
variations. Potential risks to groundwater users is further
controlled by the installation of water filtration systems for water
supply well within a 0.5-mile radius of the ash basin compliance
boundaries. Implementation of institutional controls may include
a restricted designation to further protect potential groundwater
users.
Magnitude of Residual Risk
Implementation of MNA will not result in increased residual risk,
as the current state and predicted future state does not indicate
unacceptable risk to human health or environment. Potential
risks to groundwater is further controlled by water filtration
systems to water supply users within a 0.5-mile radius of the ash
basin compliance boundaries. Implementation of institutional
controls may include a restricted designation to further protect
potential groundwater users.
Mobility,G. Reduction of Toxicity,
Treatment Process Used and Materials Treated
None. Relies on natural attenuation processes and mechanisms
such as dispersion and dilution to reduce COI concentrations to
below 02L standards.
Volume of Materials Destroyed or Treated
None. COIs are inorganic and cannot be destroyed; however,
COIs will be removed from groundwater through geochemical
processes.
Degree of Expected Reductions
COI concentration reductions will occur over time and are
anticipated to meet regulatory standards in approximately 700
years.
Irreversible Treatment
None. Natural processes are not anticipated to be reversible
based on results of extensive geochemical modeling; however,
variations in pH and reduction -oxidation in the geochemical
environment can change effectiveness.
Type and Quantity of Residuals Remaining
None. The natural attenuation processes do not create additional
residuals for inorganic COIs.
02L Standards at the Compliance Boundary
The flow and transport model predicts that concentrations of
COIs would meet 02L standards at the compliance boundary in
approximately 700 years after ash basin closure.
Page 2 of 6

Remediation Alternatives
Remediation Alternative 1
Monitored Natura
Attenuation
Monitored Natural Attenuation
(MNA) relies on natural
attenuation mechanisms to
reduce COI concentrations over
time to meet corrective action
goals. For inorganics, these
processes include adsorption to
soil and bedrock surfaces,
precipitation, ion exchange,
phyto-attenuation, dilution and
dispersion.
Q
o!
APPENDIX M, TABLE 1
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 1
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
Costs to Implement Remedial Alternative 1
Captial Costs
$963,000
Annual Costs
$198,000
Total Life Cycle Costs
$5,561,000
The cost estimate was developed to reflect the cost of
implementing MNA for the entire site. Costs to implement
MNA for the Site would include the labor and materials to
monitor and maintain appropriate wells for both Source Area
1 and Source Area 2.
Costs to implement MNA for Source Area 1 would include the
needed labor and materials to monitor the wells associated
with Source Area 1 on a semi-annual basis, and
redevelopment/replacement of wells, as necessary, and
routine labor for annual and 5-year reporting.
Life cycle costs are determined using a Net Present Value
(NPV) of expenditures for initial Capital costs and annual O&M
expenses for the duration of the remedy. A Discount Rate of
5% assumed in developing the cost estimate.
J. Community Acceptance K. Adaptive Site Management
Stakeholder Sentiment Regarding Ability to Augment the Remedy, if Needed
Implementation
It is expected that there will be positive and negative MNA is an adaptable process. Long-term groundwater
sentiment about implementation of an MNA program. No monitoring implemented as part of MNA and can be an
landowner is affected and groundwater COIs do not pose an effective tool in identifying the need for alternative
unacceptable risk to potential human or ecological receptors. approaches if unexpected changes in Site conditions occur
The remaining property is owned by Duke Energy, which is
An MNA program would not hinder or preempt the use of
anticipated to have institutional controls. Some community
other remedial approaches in the future if conditions
stakeholders might consider a 700-year time frame to
change. In fact, an effectiveness monitoring program is an
achieve remediation goals for boron to be unacceptable.
essential part of any future remedial strategy. An MNA
effectiveness monitoring program would provide
Until the final corrective action is developed and comments
information about changing Site conditions during and
are received and reviewed, assessment of community
after source control measures.
acceptance will not be fully informed
Environmental Footprint of the Remedy
The MNA remedy will impact the environment through energy
consumption and associated emissions associated with
installation of additional monitoring wells and sampling and
analysis of groundwater.
Some clearing of wooded areas would be required to install
monitoring wells and maintain access for sampling activities.
Maintenance of access will also require energy consumption.
Alternative 1 utilizes significantly fewer resources during
construction and throughout the remedial timeframe when
compared to the other remedial alternatives. Therefore,
Alternative 1 is the least energy -intensive of the remedial
alternatives being considered, providing reduced,
comparative environmental footprint metrics in overall ene
use and across all air emission parameters.
Page 3 of 6

Remediation Alternatives
Remediation Alternative 2
Groundwater Extraction and
Treatment
Groundwater extraction which
relies on purmping and removal of
groundwater to reduce COI
concentrations over time to meet
corrective action goals.
This remedy uses 20 extraction
wells to the north and northeast of
the East Ash Basin and 12
extraction wells in the comingled
zone near the DFA silo and
operational area.
Extracted water would be treated
and discharged through the
existing NPDES system.
N
Q
A. Human Health & Environment
Human Health
There is no measurable difference between evaluated Site
risk and risk indicated by background concentrations;
therefore, no material increase in risks to human health
related to the ash basin have been identified. The assessment
conservatively included potential recreational receptors in
Hyco Reservoir. Human receptors are not affected by
groundwater from the Site as water supply wells are located
upgradient or outside the drainage basin. Furthermore, 80
water supply wells within the 0.5-mile radius of the ash basin
compliance boundaries have had water filtration systems
installed.
Predictive flow and transport modeling indicate that the 02L
standard for boron could be achieved outside the compliance
boundary in approximately +180 years using active
groundwater remedial measures. Remedial Alternative 2 will
achieve a higher degree of protection for human health and
the environment in a much shorter time -frame when
compared to Remedial Alternative 1 (MNA).
Environment
The Roxboro ash basins do not cause an increase in risks to
ecological receptors (mallard duck, great blue heron,
muskrat, river otter, bald eagle, American robin, meadow
vole, red-tailed hawk, red fox and killdeer bird) evaluated for
the Hyco Reservoir exposure area, based on the results of an
ecological risk assessment performed for the Roxboro ash
basins using USEPA guidance (see Appendix Q.
APPENDIX M, TABLE 1
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 1
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
B. Compliance with Applicable Regulations
Federal
The groundwater extraction and treatment specified in
Remediation Alternative 2 would comply with USEPA CCR
Rule specified in 40 Code of Federal Regulations (CFR) §
257.
State
Alternative 2 complies with the Coal Ash Management Act
of 2014,15A NCAC 02L regulations and NCAC 02B
regulations. NPDES permitted discharge is in place. The
NPDES Permit may need to be modified to accommodate
the discharge of treated groundwater. Procurement of
Sediment and Erosion Control permits associated with
extraction and monitoring well installation is a straight-
forward process.
Local
Groundwater extraction and treatment can be
implemented in compliance with local laws and
regulations.
C. Technical & Logistical Feasibility
Ability to construct and operate technology
Technology to construct and operate a groundwater extraction
system is available. Technologies to treat extracted
groundwater exist, but require experience to successfully
operate.
Reliability of technology
Groundwater extraction is a mature technology and has been
used to implement cleanup strategies for similar COIs, but is
dependent on subsurface conditions and effectiveness of
treatment approaches. Issues such as well fouling must be
considered during the detailed design process.
Ease of undertaking additional RAs if necessary
The technology doesn't preclude implementation of other
remedial alternatives, if warranted. Groundwater extraction or
infiltration wells can be added to the proposed system or
removed from service, as warranted.
Ability to monitor effectiveness of remedy
Multiple methods can be used to monitor system effectiveness.
An effectiveness monitoring plan would be implemented to
track changes in COI concentrations over time. A system
Operations and Maintenance (O&M) plan would be implemented
to track the gallons of water extracted and the COI mass
removed on a cumulative basis. Ongoing review of data and
periodic updates to the groundwater modeling would be
performed.
Ability to coordinate and obtain approvals from
other agencies
Soil erosion and sediment control permits are relatively
straightforward and can be readily obtained from NCDEQ. An
NPDES permit exists for the facility and currently include
provisions for groundwater remediation.
Availability of services and materials
All services and materials are readily available to support the
remediation alternative. An extensive groundwater monitoring
well network already exists to support effectiveness monitoring.
D. Time Required to Initiate and Implement
Requirements for bench scale testing
Additional hydrogeologic testing, including pilot testing, may be
required to complete the design, to address heterogeneous
subsurface conditions, and confirm model predictions. Collection
of dynamic groundwater quality data from wells may be required
to confirm treatment options and design of any treatment
facilities if management of groundwater in the LRB, or discharge
under the existing NPDES permit is not viable.
Design
Detailed design activities would commence upon approval of the
CAP Update by NCDEQ. Full scale design is dependent on
hydrogeologic testing and bench testing, as required, to develop
more accurate flow rates and estimates of extracted
groundwater quality. Final locations of extraction points,
conveyance piping, electrical service, tankage and potential
treatment units would be confirmed. Detailed design of
electrical, mechanical and controls components would then be
finalized for bidding and construction.
Permitting
Soil erosion and sediment control permits are required for
installation of wells and other infrastructure that include ground
disturbance (e.g., conveyance piping). The NPDES permit can be
modified if required for the discharge of treated groundwater.
Page 4 of 6

Remediation Alternatives
Remediation Alternative 2
Groundwater Extraction and
Treatment
Groundwater extraction which
relies on purmping and removal of
groundwater to reduce COI
concentrations over time to meet
corrective action goals.
This remedy uses 20 extraction
wells to the north and northeast of
the East Ash Basin and 12
extraction wells in the comingled
zone near the DFA silo and
operational area.
Extracted water would be treated
and discharged through the
existing NPDES system.
N
Q
E. Short-term Effectiveness
Protection of Community during remediation
Community will not be impacted during active remediation and
monitoring activities as they would be performed on Duke
Energy property. Any anticipated increase in traffic on roads
leading to Roxboro due to nature of the work would be de
minimis .
Protection of workers during remediation
Work would be performed under a Health & Safety Plan, which
identifies risks and mitigation measures to protect workers and
the environment. All personal will be require relevant training
and supporting documentation to verify competency.
Environmental impacts
Remedial Alternative 2 has increased energy consumption to
operate the extraction and treatment system and will require
additional energy for construction to manufacture piping, well
materials, and to excavate trenches for piping and utilities.
Environmental impacts associated with clearing to install wells
and supporting infrastructure would be minimal and work
would be performed with a soil erosion and sediment control
permit.
Time Until Action is Complete
Predictive modeling indicates compliance to regulatory
standards at the compliance boundary in 10 years after the
system is placed into operation.
APPENDIX M, TABLE 1
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 1
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
F. Long-term Effectiveness
Adequacy and reliability of controls
An extraction system installed using predictive modeling should
be effective in reducing COI concentrations in groundwater over
time. Implementation and maintenance of an effectiveness
monitoring program would be in place to evaluate variations in
water quality from expected conditions. Alternative measures
can be taken to address variations, if warranted. Potential risks to
groundwater users is further controlled by the installation of
water filtration systems for water supply well within a 0.5-mile
radius of the ash basin compliance boundaries. Implementation
of institutional controls may include a restricted designation to
further protect potential groundwater users. An Operations &
Maintenance plan will be developed and implemented to operate
the remedial system within design parameters and document
long-term maintenance.
Magnitude of Residual Risk
Implementation of a groundwater extraction and treatment
system will not result in increased residual risk, as the current
state and predicted future state does not indicate unacceptable
risk to human health or environment. Potential risks to
groundwater is further controlled by water filtration systems to
water supply users within a 0.5-mile radius of the ash basin
compliance boundaries. Implementation of institutional controls
may include a restricted designation to further protect potential
groundwater users.
G. Reduction of Toxicity, Mobility, &Volume
Treatment process used and materials treated
Treatment of the affected groundwater would be performed
using the same water treatment system used for the decanted
water (WAB).
Volume of materials destroyed or treated
COIs would be removed from the groundwater, treated and
discharged under an NPDES permit in accordance with applicable
regulatory requirements.
Degree of expected reductions
COI concentration reductions are anticipated to meet regulatory
standards in a 10-year timeframe.
Irreversible Treatment
Mass removal would not be reversible for COIs. In -situ
treatment of COIs would not be reversible under stable
geochemical conditions.
Type and quantity of residuals remaining
Residuals may be present below regulatory standards as the
system would be intended to meet standards over time.
Residuals removed through groundwater treatment for COIs
would be managed in accordance with applicable regulatory
requirements.
02L Standards at the Compliance Boundary
The flow and transport model predicts that concentrations of
COIs would meet 02L standards at the compliance boundary in
approximately 10 years after implementation and ash basin
closure.
Page 5 of 6

Remediation Alternatives
Remediation Alternative 2
Groundwater Extraction and
Treatment
Groundwater extraction which
relies on purmping and removal of
groundwater to reduce COI
concentrations over time to meet
corrective action goals.
This remedy uses 20 extraction
wells to the north and northeast of
the East Ash Basin and 12
extraction wells in the comingled
zone near the DFA silo and
operational area.
Extracted water would be treated
and discharged through the
existing NPDES system.
N
Q
APPENDIX M, TABLE 1
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 1
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
Costs to Implement Remedial Alternative 2
Captial Costs
$3,956,000
Annual Costs
$686,000
Total Life Cycle Costs
$8,560,000
Costs to implement Remedial Alternative 2 would be based on
the assumption of installing a network of 32 extraction wells
and associated piping and control system.
Costs would also include the needed labor and materials to
monitor the wells assoicated with Source Area 1 on a semi-
annual basis, and redevelopment/replacement of wells, as
necessary, and routine labor for annual and 5-year reporting.
Life cycle costs are determined using a Net Present Value
(NPV) of expenditures for initial Capital costs and annual O&M
expenses for the duration of the remedy. A Discount Rate of
5% assumed in developing the cost estimate.
Stakeholder Sentiment Regarding
Implementation
It is expected that there will be positive and negative
sentiment about implementation of an active groundwater
remedy that includes extraction and treatment. No landowner
is anticipated to be affected and groundwater COIs do not
pose an unacceptable risk to potential human or ecological
receptors. The remaining affected property is owned by Duke
Energy, which is anticipated to implement institutional
controls.
It is anticipated that the treated groundwater would be
discharged through a NPDES permitted outfall that flows to
Hyco Reservoir and the discharge would be treated as
necessary to meet permit limits.
An expanded groundwater extraction system that addresses
the COI plume across the northwest, north and northeast
perimeter of the EAB may improve public perception. It is
anticipated that groundwater extraction and treatment would
generally receive more positive community acceptance than
MNA since it involves more active measures to extraction and
reduce COI mass from groundwater. This alternative would
likely be perceived as more robust than MNA in addressing
groundwater impacts even if human health and ecological
risks are essentially the same between MNA and groundwater
extraction.
Until the final Site remedy is developed and comments are
received and reviewed, assessment of community acceptance
will not be fully known.
Ability to Augment the Remedy, if Needed
Groundwater extraction using conventional well technology
is an adaptable process. It can be easily modified to
address changes to COI plume configuration or COI
concentrations based on actual field data. Individual well
pumping rates can be adjusted or eliminated, or additional
wells can be installed to address COI plume changes.
hile it is not expected, treatment of the groundwater
scharge can be modified to address changes in COI
incentrations or permit limits.
Environmental Footprint of the Remedy
Sustainability analysis was conducted to quantify the
environmental footprint of each remedial alternative based on
energy use and associated emissions, during the construction
phase, active remediation, and groundwater monitoring
activities.
Alternative 2 utilizes significantly more resources during
construction and throughout the remedial timeframe when
compared to the other remedial alternatives. Therefore,
Alternative 2 is the most energy -intensive of the remedial
alternatives being considered, providing significantly higher,
comparative environmental footprint metrics in overall ener<
use and across all air emission parameters.
Page 6 of 6

Remediation Alternatives
Remediation Alternative 1
Monitored Natural
Attenuation
Monitored Natural Attenuation
(MNA) relies on natural
attenuation mechanisms to
reduce COI concentrations over
time to meet corrective action
goals. For inorganics, these
processes include adsorption to
soil and bedrock surfaces,
precipitation, ion exchange,
phyto-attenuation, dilution and
dispersion.
.a
Q
APPENDIX M, TABLE 2
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 3
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
A. Human Health & Environment
Human Health
There is no measurable difference between evaluated Site
risk and risk indicated by background concentrations;
therefore, no material increase in risks to human health
related to the ash basins have been identified. The
assessment conservatively included potential recreational
receptors in Hyco Reservoir. Human receptors are not
affected by groundwater from the Site as water supply wells
are located upgradient or outside the drainage basin.
Futhermore, 80 water supply wells within the 0.5-mile radius
of the ash basin compliance boundaries have had water
filtration systems installed.
Environment
The Roxboro DFA Silos, GSA, and operational areas do not
cause an increase in risks to ecological receptors (mallard
duck, great blue heron, muskrat, river otter, bald eagle,
American robin, meadow vole, red-tailed hawk, red fox and
killdeer bird) evaluated for the Hyco Reservoir exposure
area, based on the results of an ecological risk assessment
performed for the Site using USEPA guideance (see Appendix
E).
B. Compliance with Applicable Regulations
Federal
MNA complies with USEPA CCR Rule specified in 40 Code
of Federal Regulations (CFR) § 257.
State
MNA will comply with Coal Ash Management Act of 2014
and 15A NCAC 02L .0106(I). If approved and subject to
notification requirements including the NC Department of
Transportation and NCDEQ for Sediment and Erosion
Control associated with monitoring well installation for
effectiveness monitoring. For additional details on MNA
see Appendix I.
Local
MNA would be subject to notification requirements to any
affected parties and to Person County officials per 15A
NCAC 02L.0114(b).
C. Technical & Logistical Feasibility
Ability to construct and operate technology
There are 172 monitoring wells already installed related to the
ash basins. Other than abandonment of selected wells for basin
closure and potential installation of additional monitoring
wells, no significant construction is required for
implementation.
Reliability of technology
MNA has been used successfully to achieve remedial objectives
for a wide range of COIs and geologic settings either as a
stand alone remedy, or in combination with other remediation
approaches. The CSM supports the reliability of an MNA
approach.
Ease of undertaking additional RAs if necessary
Other remedial technologies have commonly been used in
conjunction with MNA. Use of MNA will not adversely impact
the implementation of other potential remedial actions.
Ability to monitor effectiveness of remedy
Effectiveness is monitored through evaluation of COI
concentrations over time in accordance with a groundwater
effectiveness monitoring program.
Ability to coordinate and obtain approvals from
other agencies
MNA does not require interaction with other agencies to
implement.
Availability of services and materials
An extensive groundwater monitoring well network already
exists. Additional monitoring wells may be required to
complete the MNA well network. All services and materials are
readily available to support effectiveness monitoring.
D. Time Required to Initiate and Implement
Requirements for bench scale testing
There are no requirements for bench scale testing to implement
MNA.
Design
MNA is readily implementable. The existing monitoring well
network can be utilized to design the MNA network.
Permitting
Soil Erosion and Sediment Control permits are required for any
land disturbance, including well installation activities. These
permits are a straightforward to procure.
Page 1 of 9

Remediation Alternatives
Remediation Alternative 2
Groundwater Extraction and
Treatment
Groundwater extraction which
relies on purmping and removal of
groundwater to reduce COI
concentrations over time to meet
corrective action goals.
This remedy uses 22 extraction
wells along the Intake Canal north
of the Gypsum Storage Area
(GSA) and the Dry Fly Ash (DFA)
silo and operational area.
Extracted water would be treated
and discharged through the
existing NPDES system.
N
Q
APPENDIX M, TABLE 2
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 3
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
A. Human Health & Environment
Human Health
There is no measurable difference between evaluated Site
risk and risk indicated by background concentrations;
therefore, no material increase in risks to human health
related to the ash basin have been identified. The
assessment conservatively included potential recreational
receptors in Hyco Reservoir. Human receptors are not
affected by groundwater from the Site as water supply wells
are located upgradient or outside the drainage basin.
Futhermore, 80 water supply wells within the 0.5-mile radius
of the ash basin compliance boundaries have had water
filtration systems installed.
Predictive flow and transport modeling indicate that the 02L
standard for boron could be achieved outside the compliance
boundary in approximately +180 years using active
groundwater remedial measures. Remedial Alternative 2 will
achieve a higher degree of protection for human health and
the environment in a much shorter time -frame when
compared to Remedial Alternative 1 (MNA).
Environment
The Roxboro ash basins do not cause an increase in risks to
ecological receptors (mallard duck, great blue heron,
muskrat, river otter, bald eagle, American robin, meadow
vole, red-tailed hawk, red fox and killdeer bird) evaluated for
the Hyco Reservoir exposure area, based on the results of an
ecological risk assessment performed for the Roxboro ash
basins using USEPA guideance (see Appendix Q.
B. Compliance with Applicable Regulations
Federal
The groundwater extraction and treatment specified in
Remediation Alternative 2 would comply with USEPA CCR
Rule specified in 40 Code of Federal Regulations (CFR) §
257.
State
Alternative 2 complies with the Coal Ash Management
Act of 2014,15A NCAC 02L regulations and NCAC 02B
regulations. NPDES permitted discharge is in place. The
NPDES Permit may need to be modified to accommodate
the discharge of treated groundwater. Procurement of
Sediment and Erosion Control permits associated with
extraction and monitoring well installation is a straight-
forward process.
Local
Groundwater extraction and treatment can be
implemented in compliance with local laws and
regulations.
C. Technical & Logistical Feasibility
Ability to construct and operate technology
Technology to construct and operate a groundwater extraction
system is available. Technologies to treat extracted
groundwater exist, but require experience to successfully
operate.
Reliability of technology
Groundwater extraction is a mature technology and has been
used to implement cleanup strategies for similar COIs, but is
dependent on subsurface conditions and effectiveness of
treatment approaches. Issues such as well fouling must be
considered during the detailed design process.
Ease of undertaking additional RAs if necessary
The technology doesn't preclude implementation of other
remedial alternatives, if warranted. Groundwater extraction or
infiltration wells can be added to the proposed system or
removed from service, as warranted.
Ability to monitor effectiveness of remedy
Multiple methods can be used to monitor system effectiveness.
An effectiveness monitoring plan would be implemented to
track changes in COI concentrations over time. A system
Operations and Maintenance (O&M) plan would be
implemented to track the gallons of water extracted and the
COI mass removed on a cumulative basis. Ongoing review of
data and periodic updates to the groundwater modeling would
be performed.
Ability to coordinate and obtain approvals from
other agencies
Soil erosion and sediment control permits are relatively
straightforward and can be readily obtained from NCDEQ. An
NPDES permit exists for the facility and currently include
provisions for groundwater remediation.
Availability of services and materials
All services and materials are readily available to support the
remediation alternative. An extensive groundwater monitoring
well network already exists to support effectiveness
monitoring.
D. Time Required to Initiate and Implement
Requirements for bench scale testing
Additional hydrogeologic testing, including pilot testing, may be
required to complete the design, to address heterogeneous
subsurface conditions, and confirm model predictions.
Collection of dynamic groundwater quality data from wells may
be required to confirm treatment options and design of any
treatment facilities if management of groundwater in the LRB,
or discharge under the existing NPDES permit is not viable.
Design
Detailed design activities would commence upon approval of the
CAP Update by NCDEQ. Full scale design is dependent on
hydrogeologic testing and bench testing, as required, to develop
more accurate flow rates and estimates of extracted
groundwater quality. Final locations of extraction points,
conveyance piping, electrical service, tankage and potential
treatment units would be confirmed. Detailed design of
electrical, mechanical and controls components would then be
finalized for bidding and construction.
Permitting
Soil erosion and sediment control permits are required for
installation of wells and other infrastructure that include ground
disturbance (e.g., conveyance piping). The NPDES permit can
be modified if required for the discharge of treated
groundwater.
Page 2 of 9

M
Q
Remediation Alternatives
Remediation Alternative 3
Groundwater Extraction
with Clean Water
Infiltration and Treatment
Groundwater extraction relies on
pumping and removal of
groundwater to reduce
concentrations of COIs over time
to meet corrective action goals.
Infiltration of clean water is used
to flush residual concentrations of
COIs for the upper unsaturated
saprolite in order to mobilize the
COI and effect their capture my
the extraction wells.
This remedy uses 18 extraction
wells along the Intake Canal north
of the Gypsum Storage Area
(GSA) and the Dry Fly Ash (DFA)
silo and operational area. Clean
water is infiltrated into the
unsaturated saprolite along the
northeast portion of the ash basin,
between the basin and the
tributary through a series of 27
vertical clean water
infiltration/recharge wells.
Extracted water would be treated
and discharged through the
existing NPDES system.
APPENDIX M, TABLE 2
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 3
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
A. Human Health & Environment
Human Health
There is no measurable difference between evaluated Site
risk and risk indicated by background concentrations;
therefore, no material increase in risks to human health
related to the ash basin have been identified. The
assessment conservatively included potential recreational
receptors in Hyco Reservoir. Human receptors are not
affected by groundwater from the Site as water supply wells
are located upgradient or outside the drainage basin.
Futhermore, 80 water supply wells within the 0.5-mile radius
of the ash basin compliance boundaries have had water
filtration systems installed.
Predictive flow and transport modeling indicate that the 02L
standard for boron could be achieved outside the compliance
boundary in approximately +180 years using active
groundwater remedial measures. Remedial Alternative 2 will
achieve a higher degree of protection for human health and
the environment in a much shorter time -frame when
compared to Remedial Alternative 1 (MNA).
Environment
The Roxboro ash basins do not cause an increase in risks to
ecological receptors (mallard duck, great blue heron,
muskrat, river otter, bald eagle, American robin, meadow
vole, red-tailed hawk, red fox and killdeer bird) evaluated for
the Hyco Reservoir exposure area, based on the results of an
ecological risk assessment performed for the Roxboro ash
basins using USEPA guideance (see Appendix E).
B. Compliance with Applicable Regulations
Federal
The groundwater extraction, infiltration and in -situ
treatment specified in Remediation Alternative 3 would
comply with USEPA CCR Rule specified in 40 Code of
Federal Regulations (CFR) § 257.
State
Alternative 3 complies with the Coal Ash Management
Act of 2014,15A NCAC 02L regulations and NCAC 02B
regulations. NPDES permitted discharge is in place. The
NPDES Permit may need to be modified to accommodate
the discharge of treated groundwater. Procurement of
Sediment and Erosion Control permits associated with
extraction and monitoring well installation is a straight-
forward process.
Local
Groundwater extraction and infiltration can be
implemented in compliance with local laws and
regulations.
C. Technical & Logistical Feasibility
Ability to construct and operate technology
Technology to construct and operate Remediation Alternative 3
is straightforward and available. Technologies to treat
extracted groundwater exist but are less straight -forward to
operate.
Reliability of technology
Groundwater extraction with clean water infiltration is a
mature technology and has been used to implement cleanup
on similar COIs. It is strongly dependent on subsurface
conditions and effectiveness of treatment approaches.
Ease of undertaking additional RAs if necessary
The technology doesn't preclude implementation of other
remedial alternatives. Groundwater extraction or infiltration
wells can be added to the proposed system or removed from
service, as warranted.
Ability to monitor effectiveness of remedy
Multiple methods can be used to monitor system effectiveness.
An effectiveness monitoring plan would be implemented to
track changes in COI concentrations over time. A system
Operations and Maintenance (O&M) plan would be
implemented to track the gallons of water extracted and
infiltrated and the COI mass removed on a cumulative basis.
Ongoing review of data and periodic updates to the
groundwater modeling would be performed.
Ability to coordinate and obtain approvals from
other agencies
Soil erosion and sediment control permits are relatively
straightforward and can be readily obtained from NCDEQ. An
NPDES permit exists for the facility and currently include
provisions for groundwater remediation.
Availability of services and materials
All services and materials are readily available to support the
remediation alternative. An extensive groundwater monitoring
well network already exists to support effectiveness
D. Time Required to Initiate and Implement
Requirements for bench scale testing
Additional hydrogeologic testing, including pilot testing, may be
required to complete the design, to address heterogeneous
subsurface conditions, and confirm model predictions.
Collection of dynamic groundwater quality data from wells may
be required to confirm treatment options and design of any
treatment facilities if management of groundwater in the LRB,
or discharge under the existing NPDES permit is not viable.
Design
Detailed design activities would commence upon approval of the
CAP Update by NCDEQ. Full scale design is dependent on
hydrogeologic testing and bench testing, as required, to develop
more accurate flow rates and estimates of extracted
groundwater quality. Final locations of extraction points,
conveyance piping, electrical service, tankage and potential
treatment units would be confirmed. Detailed design of
electrical, mechanical and controls components would then be
finalized for bidding and construction.
Permitting
Soil erosion and sediment control permits are required for
installation of wells and other infrastructure that include ground
disturbance (e.g., conveyance piping). The NPDES permit can
be modified if required for the discharge of treated
groundwater.
Page 3 of 9

Remediation Alternatives
Remediation Alternative 1
Monitored Natural
Attenuation
Monitored Natural Attenuation
(MNA) relies on natural
attenuation mechanisms to
reduce COI concentrations over
time to meet corrective action
goals. For inorganics, these
processes include adsorption to
soil and bedrock surfaces,
precipitation, ion exchange,
phyto-attenuation, dilution and
dispersion.
.a
Q
Protection of Community
The surrounding community would not be affected during
implementation of MNA activities performed on Duke Energy
property. Any increase in traffic on roads leading to Roxboro
due to the nature of the work would be de minimis.
Worker Protection
Work would be performed under a Health & Safety Plan, which
identifies risks and mitigation measures to protect workers
and the environment. All personal will be require relavent
training and supporting documentation to verify compentency.
Environmental Impacts
There would be some migration of COI affected groundwater
would be expected as part of the attenuation process.
However, human health and ecological risk assessments do
not indicate significant risks.
Time Until Action is Complete
Predictive groundwater modeling indicates compliance to
regulatory standards at the compliance boundary in
approximately 700 years following basin closure.
APPENDIX M, TABLE 2
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 3
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
F. Long-term Effectiveness
Adequacy and Reliability of Controls
Implementation and maintenance of an effectiveness monitoring
program will be in place to evaluate variations from expected
conditions. Alternative measures can be taken to address
variations. Potential risks to groundwater users is further
controlled by the installation of water filtration systems for water
supply well within a 0.5-mile radius of the ash basin compliance
boundaries. Implementation of institutional controls may
include a restricted designation to further protect potential
groundwater users.
Magnitude of Residual Risk
Implementation of MNA will not result in increased residual risk,
as the current state and predicted future state does not indicate
unacceptable risk to human health or environment. Potential
risks to groundwater is further controlled by water filtration
systems to water supply users within a 0.5-mile radius of the
ash basin compliance boundaries. Implementation of
institutional controls may include a restricted designation to
further protect potential groundwater users.
G. Reduction of Toxicity, Mobility, &Volume
Treatment Process Used and Materials Treated
None. Relies on natural attenuation processes and mechanisms
such as dispersion and dilution to reduce COI concentrations to
below 02L standards.
Volume of Materials Destroyed or Treated
None. COIs are inorganic and cannot be destroyed; however,
COIs will be removed from groundwater through geochemical
processes.
Degree of Expected Reductions
COI concentration reductions will occur over time and are
anticipated to meet regulatory standards in approximately 700
years.
Irreversible Treatment
None. Natural processes are not anticipated to be reversible
based on results of extensive geochemical modeling; however,
variations in pH and reduction -oxidation in the geochemical
environment can change effectiveness.
Type and Quantity of Residuals Remaining
None. The natural attenuation processes do not create
additional residuals for inorganic COIs.
02L Standards at the Compliance Boundary
flow and transport model predicts that concentrations of
would meet 02L standards at the compliance boundary in
oximately 700 years after ash basin closure.
Page 4 of 9

Remediation Alternatives
Remediation Alternative 2
Groundwater Extraction and
Treatment
Groundwater extraction which
relies on purmping and removal of
groundwater to reduce COI
concentrations over time to meet
corrective action goals.
This remedy uses 22 extraction
wells along the Intake Canal north
of the Gypsum Storage Area
(GSA) and the Dry Fly Ash (DFA)
silo and operational area.
Extracted water would be treated
and discharged through the
existing NPDES system.
N
E. Short-term Effectiveness
Protection of Community during remediation
Community will not be impacted during active remediation
and monitoring activities as they would be performed on Duke
Energy property. Any anticipated increase in traffic on roads
leading to Roxboro due to nature of the work would be de
minimis .
Protection of workers during remediation
Work would be performed under a Health & Safety Plan, which
identifies risks and mitigation measures to protect workers
and the environment. All personal will be require relavent
training and supporting documentation to verify compentency.
Environmental impacts
Remedial Alternative 2 has increased energy consumption to
operate the extraction and treatment system and will require
additional energy for construction to manufacture piping, well
materials, and to excavate trenches for piping and utilities.
Environmental impacts associated with clearing to install wells
and supporting infrastructure would be minimal and work
would be performed with a soil erosion and sediment control
permit.
Time Until Action is Complete
Predictive modeling indicates compliance to regulatory
standards at the compliance boundary in +180 years after the
system is placed into operation.
APPENDIX M, TABLE 2
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 3
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
F. Long-term Effectiveness
Adequacy and reliability of controls
An extraction system installed using predictive modeling should
be effective in reducing COI concentrations in groundwater over
time. Implementation and maintenance of an effectiveness
monitoring program would be in place to evaluate variations in
water quality from expected conditions. Alternative measures
can be taken to address variations, if warranted. Potential risks
to groundwater users is further controlled by the installation of
water filtration systems for water supply well within a 0.5-mile
radius of the ash basin compliance boundaries. Implementation
of institutional controls may include a restricted designation to
further protect potential groundwater users. An Operations &
Maintenance plan will be developed and implemented to operate
the remedial system within design parameters and document
long-term maintenance.
Magnitude of Residual Risk
Implementation of a groundwater extraction and treatment
system will not result in increased residual risk, as the current
state and predicted future state does not indicate unacceptable
risk to human health or environment. Potential risks to
groundwater is further controlled by water filtration systems to
water supply users within a 0.5-mile radius of the ash basin
compliance boundaries. Implementation of institutional controls
may include a restricted designation to further protect potential
groundwater users.
G. Reduction of Toxicity, Mobility, &Volurne
Treatment process used and materials treated
Treatment of the affected groundwater would be performed
using the same water treatment system used for the decanted
water (WAB).
Volume of materials destroyed or treated
COIs would be removed from the groundwater, treated and
discharged under an NPDES permit in accordance with
applicable regulatory requirements.
Degree of expected reductions
COI concentration reductions are anticipated to meet regulatory
standards in a +180-year timeframe.
Irreversible Treatment
Mass removal would not be reversible for COIs. In -situ
treatment of COIs would not be reversible under stable
geochemical conditions.
Type and quantity of residuals remaining
Residuals may be present below regulatory standards as the
sysstem would be intended to meet standards over time.
Residuals removed through groundwater treatment for COIs
would be managed in accordance with applicable regulatory
requirements.
02L Standards at the Compliance Boundary
flow and transport model predicts that concentrations of
would meet 02L standards at the compliance boundary in
oximately +180 years after implementation and ash basin
ire.
Page 5 of 9

Remediation Alternatives
Remediation Alternative 3
Groundwater Extraction
with Clean Water
Infiltration and Treatment
Groundwater extraction relies on
pumping and removal of
groundwater to reduce
concentrations of COIs over time
to meet corrective action goals.
Infiltration of clean water is used
to flush residual concentrations of
COIs for the upper unsaturated
saprolite in order to mobilize the
COI and effect their capture my
the extraction wells.
This remedy uses 18 extraction
wells along the Intake Canal north
of the Gypsum Storage Area
(GSA) and the Dry Fly Ash (DFA)
silo and operational area. Clean
water is infiltrated into the
unsaturated saprolite along the
northeast portion of the ash basin,
between the basin and the
tributary through a series of 27
vertical clean water
infiltration/recharge wells.
Extracted water would be treated
and discharged through the
existing NPDES system.
E. Short-term Effectiveness
Protection of Community during remediation
Community will not be impacted during active remediation
and monitoring activities as they would be performed on Duke
Energy property. Any anticipated increase in traffic on roads
leading to Roxboro due to nature of the work would be de
minimis .
Protection of workers during remediation
Work would be performed under a Health & Safety Plan, which
identifies risks and mitigation measures to protect workers
and the environment. All personal will be require relavent
training and supporting documentation to verify compentency.
Environmental impacts
Remedial Alternative 3 has increased energy consumption to
operate the extraction and treatment system and will require
additional energy for construction to manufacture piping, well
materials, and to excavate trenches for piping and utilities.
Environmental impacts associated with clearing to install wells
and supporting infrastructure would be minimal and work
would be performed with a soil erosion and sediment control
permit.
Time until RA objectives are achieved
Predictive modeling indicates compliance to regulatory
standards at the compliance boundary in 10 years after the
system is placed into operation.
APPENDIX M, TABLE 2
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 3
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
F. Long-term Effectiveness
Adequacy and reliability of controls
Implementation and maintenance of an effectiveness monitoring
program would be in place to evaluate variations in water quality
from expected conditions. Alternative measures can be taken to
address variations, if needed. Risk are mitigated to potential
groundwater users by the addition of water filtration systems,
connection to municipal supply, and institutional controls
(provided by the restricted designation). An Operations &
Maintenance plan will be developed and implemented to operate
the remedial system within design parameters.
Magnitude of Residual Risk
Implementation of a groundwater extraction and treatment
system will not result in increased residual risk, as the current
state and predicted future state does not indicate unacceptable
risk to human health or environment. Potential risks to
groundwater is further controlled by water filtration systems to
water supply users within a 0.5-mile radius of the ash basin
compliance boundaries. Implementation of institutional controls
may include a restricted designation to further protect potential
groundwater users.
G. Reduction of Toxicity, Mobility, &Volume
Treatment process used and materials treated
Treatment of the affected groundwater would be performed
using the same water treatment system used for the decanted
water (WAB).
Volume of materials destroyed or treated
COIs would be removed from the groundwater, treated and
discharged under an NPDES permit in accordance with
applicable regulatory requirements.
Degree of expected reductions
COI concentration reductions are anticipated to meet regulatory
standards in a 10-year timeframe.
Irreversible Treatment
Mass removal would not be reversible for COIs. In -situ
treatment of COIs would not be reversible under stable
geochemical conditions.
Type and quantity of residuals remaining
Residuals may be present below regulatory standards as the
sysstem would be intended to meet standards over time.
Residuals removed through groundwater treatment for COIs
would be managed in accordance with applicable regulatory
requirements.
02L Standards at the Compliance Boundary
flow and transport model predicts that concentrations of
would meet 02L standards at the compliance boundary in
oximately 10 years after implementation and ash basin
ire.
Page 6 of 9

Remediation Alternatives
Remediation Alternative 1
Monitored Natural
Attenuation
Monitored Natural Attenuation
(MNA) relies on natural
attenuation mechanisms to
reduce COI concentrations over
time to meet corrective action
goals. For inorganics, these
processes include adsorption to
soil and bedrock surfaces,
precipitation, ion exchange,
phyto-attenuation, dilution and
dispersion.
.a
Q
K
APPENDIX M, TABLE 2
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 3
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
Costs to Implement Remedial Alternative 1
Captial Costs
$963,000
Annual Costs
$198,000
Total Life Cycle
$5,561,000
Costs
The cost estimate was developed to reflect the cost of
implementing MNA for the entire site. Costs to implement
MNA for the Site would be based on include the labor and
materials to monitor and maintain appropriate wells for both
Source Area 1 and Source Area 2.
Costs to implement MNA for Source Area 3 would be based
on the assumption of 5 additional monitoring well. Costs
would also include the needed labor and materials to monitor
the wells associated with Source Area 3 on a semi-annual
basis, and redevelopment/replacement of wells, as
necessary, and routine labor for annual and 5-year reporting.
Life cycle costs are determined using a Net Present Value
(NPV) of expenditures for initial Capital costs and annual
0&M expenses for the duration of the remedy. A Discount
Rate of 5% assumed in developing the cost estimate.
1. Community Acceptance
K. Adaptive Site Management
Stakeholder Sentiment Regarding
Implementation
Ability to Augment the Remedy, if Needed
It is expected that there will be positive and negative
MNA is an adaptable process. Long-term groundwater
sentiment about implementation of an MNA program. No
monitoring implemented as part of MNA and can be an
landowner is affected and groundwater COIs do not pose an
effective tool in identifying the need for alternative
unacceptable risk to potential human or ecological receptors.
approaches if unexpected changes in Site conditions
occu r.
The remaining property is owned by Duke Energy, which is
anticipated to have institutional controls. Some community
An MNA program would not hinder or preempt the use of
stakeholders might consider a 700-year time frame to
other remedial approaches in the future if conditions
achieve remediation goals for boron to be unacceptable.
change. In fact, an effectiveness monitoring program is
However, community stakeholders with concerns regarding
an essential part of any future remedial strategy. An MNA
the capital and near -term 0&M costs associated with active
effectiveness monitoring program would provide
remediation may favor a less costly alternative.
information about changing Site conditions during and
after source control measures.
Until the final corrective action is developed and comments
are received and reviewed, assessment of community
acceptance will not be fully informed.
Environmental Footprint of the Remedy
The MNA remedy will impact the environment through
energy consumption and associated emissions associated
with installation of additional monitoring wells and sampling
and analysis of groundwater.
Some clearing of wooded areas would be required to install
monitoring wells and maintain access for sampling activities.
Maintenance of access will also require energy consumption.
Alternative 1 utilizes significantly fewer resources during
construction and throughout the remedial timeframe when
compared to the other remedial alternatives. Therefore,
Alternative 1 is the least energy -intensive of the remedial
alternatives being considered, providing reduced,
comparative environmental footprint metrics in overall
energy use and across all air emission parameters.
Page 7 of 9

Remediation Alternatives
Remediation Alternative 2
Groundwater Extraction and
Treatment
Groundwater extraction which
relies on purmping and removal of
groundwater to reduce COI
concentrations over time to meet
corrective action goals.
This remedy uses 22 extraction
wells along the Intake Canal north
of the Gypsum Storage Area
(GSA) and the Dry Fly Ash (DFA)
silo and operational area.
Extracted water would be treated
and discharged through the
existing NPDES system.
N
APPENDIX M, TABLE 2
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 3
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
Costs to Implement Remedial Alternative 2
Captial Costs
$2,718,000
Annual Costs
$613,000
Total Life Cycle
$11,528,000
Costs
Costs to implement Remedial Alternative 2 would be based
on the assumption of installing a network of 18 extraction
wells, and associated piping and control system.
Costs would also include the needed labor and materials to
monitor the wells assoicated with Source Area 3 on a semi-
annual basis, and redevelopment/replacement of wells, as
necessary, and routine labor for annual and 5-year reporting.
Life cycle costs are determined using a Net Present Value
(NPV) of expenditures for initial Capital costs and annual
O&M expenses for the duration of the remedy. A Discount
Rate of 5% assumed in developing the cost estimate.
Stakeholder Sentiment Regarding
Implementation
It is expected that there will be positive and negative
sentiment about implementation of an active groundwater
remedy that includes extraction and treatment. No
landowner is anticipated to be affected and groundwater
COIs do not pose an unacceptable risk to potential human or
ecological receptors. The remaining affected property is
owned by Duke Energy, which is anticipated to implement
institutional controls.
It is anticipated that the treated groundwater would be
discharged through a NPDES permitted outfall that flows to
Hyco Reservoir and the discharge would be treated as
necessary to meet permit limits.
An expanded groundwater extraction system that addresses
the COI plume north of the GSA/DFA silo and operational
areas may improve public perception. It is anticipated that
groundwater extraction and treatment would generally
receive more positive community acceptance than MNA since
it involves more active measures to extraction and reduce
COI mass from groundwater. This alternative would likely
be percieved as more robust than MNA in addressing
groundwater impacts even if human health and ecological
risks are essentially the same between MNA and
groundwater extraction.
Until the final Site remedy is developed and comments are
received and reviewed, assessment of community
acceptance will not be fully known.
Ability to Augment the Remedy, if Needed
Groundwater extraction using conventional well
technology is an adaptable process. It can be easily
modified to address changes to COI plume configuration
or COI concentrations based on actual field data.
Individual well pumping rates can be adjusted or
eliminated, or additional wells can be installed to address
COI plume changes.
While it is not expected, treatment of the groundwater
discharge can be modified to address changes in COI
concentrations or permit limits.
Environmental Footprint of the Remedy
Sustainability analysis was conducted to quantify the
environmental footprint of each remedial alternative based
on energy use and associated emissions, during the
construction phase, active remediation, and groundwater
monitoring activities.
Alternative 2 was the most emission -intensive remedial
alternative being considered. Alternative 2 presents lower,
but generally comparable, energy consumption metrics when
measured against Alternative 3. Although Alternative 2 uses
extraction wells, no clean -water infiltration wells are used
generating a lower material -related environmental footprint
for the construction phase. However, the extended
timeframe of remediation system operation for Alternative 2
(180 years) when compared to Alternative 3 (10 years)
produces air emissions exceeding the levels of Alternative 3.
The quantitative analysis of the environmental footprints of
the remedial alternatives under consideration for this CAP
indicates Alternative 2 to be the least sustainable option.
Page 8 of 9

M
9
Remediation Alternatives
Remediation Alternative 3
Groundwater Extraction
with Clean Water
Infiltration and Treatment
Groundwater extraction relies on
pumping and removal of
groundwater to reduce
concentrations of COIs over time
to meet corrective action goals.
Infiltration of clean water is used
to flush residual concentrations of
COIs for the upper unsaturated
saprolite in order to mobilize the
COI and effect their capture my
the extraction wells.
This remedy uses 18 extraction
wells along the Intake Canal north
of the Gypsum Storage Area
(GSA) and the Dry Fly Ash (DFA)
silo and operational area. Clean
water is infiltrated into the
unsaturated saprolite along the
northeast portion of the ash basin,
between the basin and the
tributary through a series of 27
vertical clean water
infiltration/recharge wells.
Extracted water would be treated
and discharged through the
existing NPDES system.
APPENDIX M, TABLE 2
REMEDIATION ALTERNATIVES SUMMARY
SOURCE AREA 3
CORRECTIVE ACTION PLAN UPDATE
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
Costs to Implement Remedial Alternative 3
Captial Costs
$5,185,000
Annual Costs
$769,000
Total Life Cycle
$10,299,000
Costs
Costs to implement Remedial Alternative 3 would be based
on the assumption installing a network of 18 groundwater
vertical extraction wells, 27 vertical clean water infiltration
wells, and associated piping and control system.
Costs would also include the needed labor and materials
tomonitor the wells assoicated with Source Area 3 on a semi
annual basis, and redevelopment/replacement of wells, as
necessary, and routine labor for annual and 5-year reporting.
Life cycle costs are determined using a Net Present Value
(NPV) of expenditures for initial Capital costs and annual
O&M expenses for the duration of the remedy. A Discount
Rate of 5% assumed in developing the cost estimate.
Stakeholder Sentiment Regarding
Implementation
It is expected that there will be positive and negative
sentiment about implementation of an active groundwater
remedy that includes extraction and treatment. No
landowner is anticipated to be affected and groundwater
COIs do not pose an unacceptable risk to potential human or
ecological receptors. The remaining affected property is
owned by Duke Energy, which is anticipated to implement
institutional controls.
It is anticipated that the treated groundwater would be
discharged through a NPDES permitted outfall that flows to
Hyco Reservoir and the discharge would be treated as
necessary to meet permit limits.
An expanded groundwater extraction system and clean water
infiltration system that addresses the COI plume north of the
GSA/DFA silo and operational areas may improve public
perception. It is anticipated that groundwater extraction and
treatment would generally receive more positive community
acceptance than MNA since it involves more active measures
to extraction and reduce COI mass from groundwater. This
alternative would likely be percieved as more robust than
MNA in addressing groundwater impacts even if human
health and ecological risks are essentially the same between
the alternatives.
Until the final Site remedy is developed and comments are
received and reviewed, assessment of community
acceptance will not be fully known.
Ability to Augment the Remedy, if Needed
Groundwater extraction and infiltration using conventional
well technology are adaptable processes. They can be
easily modified to address changes to COI plume
configuration or COI concentrations. Individual well
pumping/infiltration rates can be adjusted or eliminated
or additional wells can be installed to address COI plume
changes.
While it is not expected, treatment of the groundwater
discharge can be modified to address changes in COI
concentrations or permit limits.
Environmental Footprint of the Remedy
Sustainability analysis was conducted to quantify the
environmental footprint of each remedial alternative based
on energy use and associated emissions, during the
construction phase, active remediation, and groundwater
monitoring activities.
Alternative 3 was the second -most emission -intensive
remedial alternative being considered. Alternative 3 presents
higher but generally comparable, energy consumption
metrics when measured against Alternative 2. Alternative 3
uses extraction wells and clean -water infiltration wells,
generating a lower material -related environmental footprint
for the construction phase. However, the extended
timeframe of remediation system operation for Alternative 3
(10 years) when compared to Alternative 2 (180 years)
produces air emissions significantly less than the levels of
Alternative 3.
The quantitative analysis of the environmental footprints of
the remedial alternatives under consideration for this CAP
indicates Alternative 3 to be the least sustainable option.
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