NC0004987_Appropriate Applicability Dates 2016_20160513

DUKE
Harry K.Sideris
nt
ENERGY® ental,Health
&eSafety
Environmental,Health&Safety
526 S. Church Street
Mail Code:EC3XP
Charlotte,NC 28202
[phone]
May'9, 2016
Jeffrey O. Poupart
Water Quality Permitting Section Chief
Division of Water Resources RECEIVED/NCDEQ/DWR
Department of Environmental Quality
State of North Carolina MAY 13 2016
1617 Mail Service Center Water Quality
Raleigh, NC 27699-1617 Permitting Section
Subject: Marshall Steam Station
Appropriate Applicability dates for Compliance with the new Effluent Guidelines Rule
Dear Mr. Poupart:
Duke Energy (Duke) submits the attached information as ajustification for appropriate applicability dates
for compliance with the new Effluent Guidelines Rule (ELG Rule) (80 Fed. Reg. 67,838 (Nov. 3, 2015))
at Marshall Steam Station (MSS), located in Mooresville, North Carolina. The ELG Rule sets a range of
possible applicability dates for compliance with the new best available technology (BAT) limits for
bottom ash transport water (zero discharge) and FGD wastewater (numeric limits for selenium, arsenic,
mercury, and nitrate/nitrite), as well for fly ash transport water(zero discharge).
As the rule makes clear BAT limits may apply – depending on the individual circumstances of the
facilities subject to the rule–any time within the window of November I, 2018 to December 31, 2023. In
selecting an appropriate applicability date for each waste stream subject to the new BAT limits, the
permitting authority is called upon to determine an "as soon as possible" date when supplied with
appropriate information by the permittee. The attached provides the appropriate information justifying the
following applicability dates:
— Bottom Ash Transport Water: To convert the wet bottom ash transport system at MSS to a closed
loop system, Duke plans to install a remote mechanical drag chain system (RMDS). Duke would
like to request January 31, 2021 as the applicability date for the zero discharge of bottom ash
transport water, assuming a permit effective date of July I, 2016.
— FGD wastewater: Duke anticipates that it will need to replace, in its entirety, the existing FGD
wastewater treatment system at MSS. Duke would like to request January 31, 2021 as the
applicability date for the BAT limits for FGD wastewater, assuming a permit effective date of
July I, 2016.

i
Mr. Poupart
Appropriate Applicability dates for Compliance with the new Effluent Guidelines Rule
Page 2
— Fly Ash Transport Water: Fly ash is handled dry during normal operation; therefore, Duke is not
requesting an applicability date for the zero discharge of fly ash transport water beyond
November 1, 2018.
If you have any questions or need to discuss further, contact Richard Baker at 704-382-7959.
Sincerely,
Harry Sideris
SVP- Environmental, Health & Safety
Enclosures

Marshall Steam Station: Effluent Guidelines Rule
Justification for Applicability Dates
A. Introduction
Duke Energy (Duke) is working diligently to develop and refine an optimized schedule for the
installation and upgrades to wastewater treatment systems to comply with the Steam Electric Power
Generating Effluent Limitation Guidelines (ELG) at seven coal-fired stations in North Carolina. Duke
submits the following information as a justification for appropriate applicability dates for compliance
with the new Effluent Guidelines Rule (ELG Rule) (80 Fed. Reg. 67,838 (Nov. 3, 2015)) at Marshall
Steam Station (MSS), located in Mooresville, North Carolina based on the preliminary fleet wide
optimization schedule.
MSS is a four-unit coal fired station with a total generating capacity of 2,110 megawatts (MW). Units
1 and 2 have a rated capacity of 385 MW each and Units 3 and 4 have a rated capacity of 670 MW
each. MSS currently discharges treated bottom ash transport water, and FGD wastewater. Under
normal plant operations, fly ash is collected dry and either disposed in a permitted on-site landfill or
transported offsite for beneficial reuse. If the dry fly ash collection system is not operating, the fly ash
is sluiced to the ash basin in which the transport water is treated in the ash basin and subsequently
discharged through outfall 002. Bottom ash from the boilers is sluiced with transport water to a
holding cell for recycling activities. The transport water is treated by the ash basin and is discharged
through outfall 002. The FGD wastewater is sent to a solids removal system followed by a vertical
flow wetland and then constructed wetlands prior to discharging to the ash basin via internal outfall
004.
The ELG Rule sets a range of possible applicability dates for compliance with the new BAT limits for
bottom ash transport water (zero discharge) and FGD wastewater (numeric limits for selenium,
arsenic, mercury, and nitrate/nitrite), as well for fly ash transport water (zero discharge). The
regulation provides that all permits issued after the effective date of the rule (January 4, 2016) should
contain applicability dates for compliance with the BAT limits, and that those dates should be "as
soon as possible"but not sooner than November I, 2018 and not later than December 31, 2023.
For MSS, since the plant's final NPDES permit will be issued after January 4, 2016, but before
November 1, 2018, EPA specifically instructs permit writers to "apply limitations based on the
previously promulgated BPT limitations or the plant's other applicable permit limitations until at
least November 1, 2018." 80 Fed. Reg. at 67,883, col. I (emphasis added). As the rule makes clear,
however, BAT limits may apply —depending on the individual circumstances of the facilities subject
to the rule—any time within the window of November 1, 2018 to December 31, 2023. In selecting an
appropriate applicability date for each waste stream subject to the new BAT limits, the permitting
authority is called upon to determine an "as soon as possible" date.
The ELG Rule provides a very specific definition for"as soon as possible." The permit writer—when
supplied with appropriate information by the permittee—must consider a range of factors that affect
the timing of compliance. Those factors are as follows:
(1)Time to expeditiously plan (including to raise capital),design, procure, and install
equipment to comply with the requirements of this part.

(2)Changes being made or planned at the plant in response to:
(i)New source performance standards for greenhouse gases from new fossil fuel-
fired electric generating units, under sections I 11, 301, 302, and 307(d)(I)(C) of the
Clean Air Act, as amended,42 U.S.C. 7411, 7601, 7602, 7607(d)(1)(C);
(ii) Emission guidelines for greenhouse gases from existing fossil fuel-fired electric
generating units, under sections 1 1 1, 301, 302,and 307(d) of the Clean Air Act, as
amended,42 U.S.C. 7411, 7601, 7602, 7607(d); or
(iii) Regulations that address the disposal of coal combustion residuals as solid waste,
under sections 1006(b), 1008(a), 2002(a), 3001,4004, and 4005(x) of the Solid Waste
Disposal Act of 1970,as amended by the Resource Conservation and Recovery Act
of 1976, as amended by the Hazardous and Solid Waste Amendments of 1984, 42
U.S.C. 6906(b), 6907(a), 6912(x), 6944, and 6945(a).
(3) For FGD wastewater requirements only, an initial commissioning period for the
treatment system to optimize the installed equipment.
(4) Other factors as appropriate.
40 C.F.R. § 423.11(t).
The wastewater treatment systems at MSS will undergo significant modifications and in most cases
complete replacement to comply with the revisions to the ELG Rule. Duke would like sufficient time
to select, design and install the most cost effective technology at MSS to comply with the ELG limits
and reduce the burden to the ratepayers. We have prepared a preliminary timeline for planning,
designing, procuring, constructing and optimizing the technology once it is selected, for each
applicable waste stream. Based on our preliminary analysis, we request the following applicability
dates:
— Bottom Ash Transport Water: To convert the wet bottom ash transport system at MSS to a
closed loop system, Duke plans to install a remote mechanical drag chain system (RMDS).
Duke would like to request January 31,2021 as the applicability date for the no discharge of
bottom ash transport water,assuming a permit effective date of July I, 2016. Duke anticipates
that equipment will be installed by December 31, 2019 to comply with the North Carolina-
Coal Ash Management Act (NC-CAMA) and the Coal Combustion Residual _(CCR) rule.
These rules, however, only regulate the material, not the water. As discussed below, Duke
will need a 13 month window to optimize the system to operate as a zero discharge system. In
addition, the extent and complexity of the permits required are unknown at this time. Duke,
therefore, allocated 6 months to account for potential permitting delays.
— FGD wastewater: Duke anticipates that it will need to replace, in its entirety, the existing
FGD wastewater treatment system at MSS. We plan to evaluate the development of a new
physical/chemical system augmented by a selenium reduction system. Duke would like to
request January 31, 2021 as the applicability date for the best available technology (BAT)
limits for FGD wastewater, assuming a permit effective date of July 1, 2016.
— Fly Ash Transport Water: Fly ash is handled dry during normal operation; therefore, Duke is
not requesting an applicability date for the zero discharge of fly ash transport water beyond
November 1,2018.
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The following provides necessary information justifying the requested applicability dates provided
above.
B. Bottom Ash Transport Water
As stated above, significant portions of the bottom ash transport system at MSS will need to be
replaced to comply with the no discharge limit of bottom ash transport water (BATW). The rule
identified dry handling or closed-loop systems as the BAT technology basis for control of pollutants
in bottom ash transport water. Specifically, a mechanical drag system (MDS) was identified as the
technology basis for a dry handling system, where as a RMDS was identified as the technology basis
for a closed-loop system. Duke is planning on installing a RMDS at MSS to handle bottom ash dry.
The system will be designed to operate in a closed-loop mode to meet the zero discharge limits for
BATW. Duke anticipates 55 months from the effective date of the permit will be needed to design,
install and commission the RMDS as a zero discharge system based on the following preliminary
timeline.
Remote Mechanical Drag System (RMDS)
Activity Duration (Months)
Design 11
• Siting 4
• Engineering 7
Procurement 12
Potential Permitting Delays 6
Construction/Tie-in 13
Optimization & Operational Ex erience 13
• Commissioning 2
• Start-Up 6
Total: 55
1)Even though is it estimated that commissioning and start-up can occur in 8 months, Duke
anticipates needing a 13 month window to obtain the necessary operating time at full load.
Assuming a permit effective date of July 1 2016, Duke estimates the system can be installed and
operated to comply with the zero discharge limit of BATW on or before January 31, 2021. To design,
procure, construct and optimize the RMDS at MSS to operate as a closed-loop system, the following
steps must be taken:
Design &Engineering,
Due to the simultaneous implementation of programs, such as the CCR Rule and NC-LAMA across
applicable sites in North Carolina, engineering and technology resources are limited. Duke, therefore,
estimates the design and engineering process will take 11 months. Some of the activities within the
water balance and siting task will occur concurrently; however the design cannot be completed until
the siting task is completed. The permitting process, if necessary, will be initiated in the design and
engineering phase, but it is assumed permit receipt/approval will be conducted concurrently with the
design and procurement phase and will be completed prior to the construction phase. The following
tasks will need to be completed.
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Water Balance
The first step in the design process of the RMDS is to develop a detailed water balance of the current
BATW. To operate the system as a zero discharge system, there is a balance between the inputs of
water into the system and the outputs of water through evaporation and bottom ash removal. This is
necessary to determine if any additional treatment of the BATW is needed to avoid increase in fines
and concentration of other constituents that could affect equipment operability.
In addition, several non-BATW waste streams are currently commingled and treated along with
BATW. The flow of these waste streams will be rerouted from the BATW system to a new
wastewater treatment system. This will require the streams to be characterized for both volumetric
flow and constituent make-up in order to size and design an appropriate treatment system. It is
important to note that not all waste streams discharge continuously or simultaneously. Some waste
streams discharge intermittently based on activity occurrence, such air preheater and precipitator
washes, while others may only discharge under certain rainfall events. In addition, many waste
streams do not discharge if the unit is not running. With most coal-fired units operating in an
infrequent mode, the opportunities to collect samples are limited and the operation schedule could
affect the schedule of this task.
Upon completion of the water balance, detailed engineering of the RMDS system and piping reroutes
of non-BATW can commence.
Siting
The RMDS will need to be sited appropriately to avoid any historical or current coal combustion
product disposal (CCP) sites and avoid construction areas that will be used to complete closure of the
ash basins at MSS. In addition, Duke will attempt to site the system to avoid waters of the U.S.
(WOTUS). However, based on the final siting of the system, WOTUS may not be avoided, and
permits from the U.S. Army Corps of Engineers may be required.
Permitting
If WOTUS cannot be avoided, then permitting from the U.S. Army Corps of Engineers (USACE) will
be needed. At this time, it is unknown whether a USACE permit will be required or the type of permit
that may be required (nationwide permit (NPW) or individual permit). Duke, therefore, has included
12 months in the schedule to prepare and obtain any necessary USACE permits.
Once the RMDS is commissioned, the permitted discharge flows will change drastically. The amount
of water discharged could be reduced by as much as 85%. In addition, these flows typically were
treated along with the BATW in the ash basin. Duke, therefore, will need to design, and construct a
new treatment system for these low volume wastes. The size and technology of the treatment system
will be determined based on the water characterization study discussed above. With significant
changes to the characteristics of the permitted discharge, Duke anticipates a NPDES permit
modification will be required to revise the permit to account for the changes in flow and constituent
make-up.
In addition, based on the final siting of the low volume wastewater treatment system, a new outfall
may need to be constructed for the discharge of the effluent from this new wastewater treatment
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system. The construction of a new outfall would require a permit/approval from the Federal Energy
Regulatory Commission (FERC) because Lake Norman is a FERC regulated reservoir. The FERC
approval process requires all other permits are received prior to submitting the approval application.
Even though the permitting task will be initiated during the design and engineering phase, it is expect
to continue through the procurement phase and up to the construction phase. In addition, the extent
and complexity of the permits required are unknown at this time. The required permits will be
evaluated during the engineering and design phase. Since time needed to prepare the permit
applications and the time needed to receive the permits is uncertain, Duke allocated 6 months to
account for potential permitting delays.
Procurement
After the design is complete, Duke will initiate the process to procure the necessary outside resources
to construct and install the new wastewater treatment systems. This process will involve the following
steps:
— Evaluate potential vendors for proposal solicitation;
— Develop and submit request for proposal (RFP) to selected vendors;
— Conduct a review and vendor selection based on the received bids;
— Develop required contract documents;
— Acquire materials (potentially from overseas), which involves:
o Shipment, and
o Equipment Fabrication
— Fabrication and inspection of equipment.
RMDS have a fabrication queue that is dependent on total industry-wide demand. Duke, therefore,
has allocated 12 months to acquire the necessary materials.
Construction
Once all the necessary materials are procured, Duke estimates construction of the RMDS will take
approximately 13 months. In addition, the tie-in of the RMDS to each individual generating unit will
need to occur during outages, which are anticipated to occur between March to May and October to
November depending on generation demand.
Optimization and Operational Experience
As stated above, Duke is planning to have the equipment installed by December 31, 2019 at the latest
to meet the obligations under CAMA, in addition, to any CCR requirements. Again, these rules
regulate the bottom ash material, not the transport water. Given the system will continue to utilize
water to transport bottom ash, time will be needed to gain operational experience and optimize the
system to meet the zero discharge limit. Duke estimates a 13 month window will be required to gain
the necessary operational experience and fine-tune the system. The 13 month window is estimated
based on the potential that the station may only be operating at full load during the winter and
summer months. Therefore, a 13 month window will be needed to acquire 2 to 3 month optimization
period and 6 to 9 months of operating experience with the system at full load.
5

C. New Wastewater Treatment System
As discussed above, with the removal of several non-BATW waste streams from the bottom ash
transport system, a new wastewater treatment system will need to be designed and constructed for co-
treatment of low volume waste and other regulated process streams per the CCR rule, ELGs, and
NDPES permitting requirements. The activities associated with the new wastewater treatment system
will be conducted concurrently with the other design activities at the site. These waste streams are not
subject to the applicability date in the ELG rule, therefore, Duke is not requesting a compliance date,
but this task will need to be completed prior to the effective date of the zero discharge of BATW.
Duke anticipates 30 months will be needed to design, install and commission the new wastewater
treatment system, based on the following preliminary timeline.
New Wastewater Treatment System
Activity Duration (Months)
Siting 3
Engineering 6
Procurement 3
Construction/Tie-in 9
Commissioning 3
Start-Up 6
Total: 30
D. FGD Wastewater
Duke anticipates that it will need to replace in its entirety the existing FGD wastewater treatment
system at MSS. The existing constructed wetlands are located within a CCR disposal area, which may
need to be excavated or capped in place per NC-CAMA. Duke is anticipating installing a
physical/chemical treatment system and a selenium reduction technology. The selenium reduction
technology has not yet been selected and Duke will be evaluating suitable technologies based on cost
and feasibility. EPA recognizes that designing, procuring, installing, and optimizing an FGD
wastewater treatment system is a complicated and time-consuming undertaking, involving much
study and careful planning. For example, EPA states:
"For plants that are planning to include fuel flexing in their operations, in the years
prior to the installation and operation of the FGD wastewater treatment system, the
plant should consider sampling the untreated FGD wastewater to evaluate the
wastewater characteristics that are present based on the differing fuel blends. Based
on those characteristics, the plant will be better able to design a system that can
properly treat its FGD wastewater given variability that might occur at the plant, and it
will be better prepared to adjust chemical dosages in the chemical precipitation system
to mitigate the variability in the wastewater that enters the biological treatment
system."
Response to Comments, p. 5-387.
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EPA also states:
"While EPA has based the effluent limitations and standards for selenium and
nitrate/nitrite (as N) for FGD wastewater based on the performance of the Allen and
Belews Creek biological treatment systems, EPA does not contend that every plant in
the industry can simply take the design parameters from those two plants, install the
biological treatment system, and meet the effluent limitations. Each plant will need to
work with engineering and design firms to assess the wastewater characteristics
present at their plant to determine the most appropriate technologies and design the
system accordingly meet the effluent limitations. Therefore, some plants may need to
design the bioreactors to provide additional bed contact time (as provided by the
hydraulic residence time and volume of biomass and carbon substrate), while other
plants may find they need less."
Response to Comments, p. 5-389
Duke anticipates .55 months from the effective date of the permit will be needed to design, install and
commission the FGD wastewater treatment system to meet the BAT limits based on the following
preliminary timeline.
FGD WWT Upgrade
Activity Duration (Months)
Design & Engineering 10
• Siting 4
• Engineering 6
Procurement 12
Potential Permitting Delays 6
Construction/Tie-in 12
Start-up & Optimization' 15
• Commissioning 6
• Start-Up 6
Total: 1 55
1) Duke is allocating a 15 month window to complete the commissioning and start-up under all
expected operating conditions from full load to partial load to periods of no load.
Assuming a permit effective date of July 1 2016, Duke estimates the system can be installed and
commissioned to meet the BAT limits on or before January 31, 2021. To design, procure, construct
and commission the FGD WWT system at MSS, the following steps must be taken:
Design & Engineering
As with the RMDS, engineering and technology resources are limited due to regulatory requirements
for concurrent implementation of programs, such as the CCR Rule and NC-CAMA across applicable
sites in North Carolina. Duke is, therefore, estimating 10 months to complete the design and
engineering phase of the project.
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Siting
As with the RMDS, the FGD WWT system will need to be sited to avoid any former or current CCR
sites and avoid construction areas that will be used to complete closure of the ash basins at MSS.
Additionally, Duke will need to site the system to avoid nuisance odor outside the property boundary.
Duke will also attempt to site the system to avoid WOTUS. However, based on the final siting of the
system WOTUS may not be avoided, and permits from the U.S. Army Corps of Engineers may be
required.
Technology Selection
Duke has significant experience in the design, construction and operation of biological treatment
systems for selenium reduction. Based on Duke's experience, biological treatment alone may not be a
fool proof technology based on the characteristics of the coal. Duke, therefore, is obligated to review
and evaluate whether other suitable technologies are available to treat FGD wastewater for selenium
reduction at MSS. Duke will be working closely with utility organizations, such as the EPRI, to
identify suitable technologies for the removal of selenium from FGD wastewater and possibly
additional polishing steps that may be required to meet the limits.
Upon completion of the siting and technology selection, the engineering design of the system will be
completed.
Permitting
If WOTUS cannot be avoided, then permitting from the U.S. Army Corps of Engineers (USACE) will
be needed. At this time, it is unknown whether a USACE permit will be required or the type of permit
that may be required (nationwide permit (NPW) or individual permit). Duke, therefore, has included
12 months in the schedule to prepare and obtain any necessary USACE permits.
The installation of the FGD WWT may change the characteristics of the final discharge, therefore, a
NPDES permit modification may be required to revise the permit to account for the changes in flow
and constituent make-up.
Even through the permitting task will be initiated during the design and engineering phase, it is expect
to continue through the procurement phase and up to the construction phase. In addition, the extent
and complexity of the permits required are unknown at this time. The required permits will be
evaluated during the engineering and design phase. Since time needed to prepare the permit
applications and the time needed to receive the permits is uncertain, Duke allocated 6 months to
account for potential permitting delays.
Procurement
After the design is complete, Duke will initiate the process to procure the necessary outside resources
to construct and install the new wastewater treatment systems. This process will involve the following
steps:
— Evaluate potential vendors for proposal solicitation;
— Develop and submit a request for proposal (RFP) to selected vendors;
8

— Conduct a review and vendor selection based on the received bids;
— Develop required contract documents;
— Acquire materials (potentially from overseas), which involves:
o Shipment, and
o Equipment Fabrication
— Fabrication and inspection of equipment.
The selenium reduction technology will have a fabrication queue that is dependent on total industry-
wide demand. Duke, therefore, has allocated 12 months to acquire the necessary materials.
Additionally, raw materials needed may have an extended lead-time from time of order to delivery,
such as the granulated activated carbon used in the biological system, which has a lead time of 12
months.
Construction/Tie In
Once all the necessary materials are procured, Duke estimates construction of the FGD WWT will
take approximately 12 months to complete. In addition, the tie-in of the FGD WWT to each
individual FGD scrubber will need to occur during outages, which are anticipated to occur between
March to May and October to November depending on generation demand.
Commissioning& Start-up
1
Duke estimates that commissioning and start-up of the FGD WWT will take 12 months to complete,
6 months for each task. Duke, however, is allocating a 15 month window to complete the
commissioning and start-up under all expected operating conditions from full load to partial load to
periods of no load. This will allow the identification of necessary actions that need to be completed in
order to maintain the system under different operating scenarios.
E. EPA Provided A Range of Applicability Dates To Allow For Coordination Across Regulatory
Requirements and to Promote Orderly Decisions
The steam electric industry is in the midst of major transitions driven by new environmental
regulatory requirements in the air, waste, and water arenas. In the ELG Rule, EPA explicitly
acknowledged the complications of planning and executing ELG retrofits while developing and
executing compliance strategies under the other rules. EPA made it clear that the range of
applicability dates provided in the ELG Rule are supposed to be implemented in a manner that avoids
stranded costs and promotes orderly decisionmaking. For instance, EPA states:
"From an environmental protection/coordination standpoint, with the increased use of
flue gas desulfurization scrubbers and Flue gas mercury controls in response to air
pollution-related requirements, this rule makes sense from a holistic environmental
protection perspective and from the perspective of coordinating across rules affecting the
same sector. This final ELG controls the discharges associated with these particular
waste streams."
Response to Comments, p. 8-388.
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EPA also states that the permitting authority may "account for time the facility needs to coordinate all
the requirements of this rule, along with other regulatory requirements, to make the correct planning
and financing decisions, and to implement the new requirements in an orderly and feasible way."
Response to Comments, p. 8-129.
At Marshall, we need to coordinate our ELG implementation strategy with CCR and NC-CAMA
rules. For both the CCR and CAMA rules, we are evaluating one approximately 394-acre ash pond to
determine whether it meets the locational restrictions of 40 C.F.R. § 257.60 - .64. The future of the
ash pond under both of these rules will determine whether it is available or not to receive legacy
wastewaters (i.e., those wastewaters generated before the applicability date for bottom ash transport
water retrofits) and continue to receive non-BATW. In addition, as discussed above, the final
determination of the extent of the ash pond, as well as the closure method could have significant
ramifications for the siting of both the RMDS and FGD WWT.
F. ELG Implementation Should be Coordinated with the Clean Power Plan (CPP)to Avoid
Stranded Costs
The ELG Rule clearly contemplates that the compliance timelines for its requirements should account
for any applicable obligations under the CPP. However, the affected units at Marshall will not know
their individual obligations under the CPP until well after November I, 2018. As promulgated by
EPA, the CPP's emission guidelines do not apply directly to units. Instead, states are responsible for
developing state plans setting forth requirements applicable to individual units that implement those
emission guidelines. These state plans are subject to review and approval by EPA. If EPA determines
that the state has not submitted an approvable plan, then EPA will promulgate a federal plan in its
place. The timeline the CPP provides for developing and reviewing these state plans involves
numerous steps.
The initial deadline for state plan submittal was September 6, 2016. 40 C.F.R. § 60.5760(a). The
vast majority of states were expected to seek and obtain a two-year extension for final state plan
submittal until September 6, 2018. See id. § 60.5760(b). However, the Supreme Court issued a stay
of the CPP on February 8, 2016. Thus, the timing of the requirements of the CPP is uncertain at this
time, as we wait further decisions by the Supreme Court. Duke would like to request the option to
revise the applicability dates for the ELG requirements if the stay of the CPP is lifted and the
operation of MSS will be affected.
Statements in the Response to Comments regarding stranded costs apply to any rule, not just the CPP.
EPA explains in the Response to Comments that it provided flexibility in applicability dates so that
facilities could consider all new regulatory requirements and then have an adequate time to plan and
implement accordingly, and thus avoid stranded costs:
"EPA is sensitive to the need to provide sufficient time for steam electric power plants to
understand, plan for, and implement any changes to their operation to meet their
environmental responsibilities, and agrees with the commenter that transparency of
requirements is important for minimizing "stranded investments." ...Furthermore, as
described in the preamble, the final rule provides time for plant owners or operators to
implement changes to plant operations in order to meet the final limitations and
standards, as well as Flexibility to permitting authorities in implementing the final rule.
10

The Agency specifically considered the timing of requirements of other environmental
regulations in establishing implementation requirements for the ELGs, in order to provide
steam electric power plants time to consider and implement their strategy for
compliance."
Response to Comments, p. 8-388.
Even though the implementation and effects of the CPP are uncertain, North Carolina Department of
Environmental Quality(NCDEQ) is justified providing flexibility in the applicability dates from other
regulatory requirements such as the CCR and NC-CAMA, as discussed above.
G. The Proposed Schedules Help To Maintain Marshall's Availability to the Grid, Which
Promotes Grid Reliability
Duke developed the proposed BATW retrofit schedule and its applicability date with grid reliability
in mind. The dispatch of units at MSS varies throughout the year. Typically one unit is operating
throughout the year and all four units are typically dispatched from December to March and June thru
September. Therefore, the final tie-in schedule will avoid these months and more than likely tie-ins
will need to occur across more than one outage.
EPA explicitly notes that the permitting authority should consider grid reliability in setting
applicability dates: "EPA's decision is also designed to allow, more broadly, for the coordination of
generating unit outages in order to maintain grid reliability and prevent any potential impacts on
electricity availability, something that public commenters urged EPA to consider." 80 Fed. Reg. at
67,854,col. 2. See also Response to Comments, p. 8-138.
Also, EPA clearly anticipated that much of the new technology required for retrofits to bottom ash
transport water and FGD wastewater systems would be constructed in a manner that would not
interrupt routine facility operations, and then tied in during regularly scheduled plant or unit outages.
According to the preamble, the timing of the final rule"enables facilities to take advantage of planned
shutdown or maintenance periods to install new pollution control technologies." 80 Fed. Reg. at
67,854, col. 2.
EPA also recognizes that tie-ins of new equipment may need to occur across more than one outage.
EPA states: "the need to span installation of equipment over separate unit outages [is] a consideration
that can be incorporated into the permit writer's determination of the `as soon as possible' date,
assuming the plant provides documentation demonstrating such a need." Response to Comments, p.
8-54.
Il