NC0004987_Comments on Draft Permit 2015_20150507 (2)

Harry K.Sideris
•
dill) DUKE Senior Vice President
Environmental,Health&Safety
le ENERGY® 526 South Church Street
Mail Code EC3XP
Charlotte,NC 28202
[phone]
May 4, 2015
North Carolina Department of
Environment and Natural Resources RECEIVEDIDENRIDWR
Wastewater Permitting
1617 Mail Service Center MAY - 7 2015
Raleigh, NC 27699-1617
Water Quality
Permitting Sectior
Subject: Comments on the draft NPDES Permit for Marshall Steam Station
Permit No.: NC0004987
Attention Wastewater Permitting:
The North Carolina Department of Environment and Natural Resources (NCDENR) Division of Water
Resources (the Division) issued a draft National Pollutant Discharge Elimination System (NPDES) Permit
for the Duke Energy Marshall Steam Station on March 6, 2015. Duke Energy Carolinas LLC(Duke Energy)
commends NCDENR for developing the draft permit and recognizing the existing discharges from the
facility's outfalls will not cause contravention of the state water quality standards or EPA criteria. Duke
Energy continues to work as quickly as possible to close the ash basins and finalizing this wastewater
permit is a critical step to advance the ash basin closure process. In order to facilitate the closure
process, Duke Energy needs permit conditions that are reasonable while ensuring the discharges will not
adversely affect water quality. Duke Energy, therefore, respectfully submits the following comments on
the draft permit.
Comments on the Develooment of the Technology Based Effluent Limits ITBELS)
The permit establishes technology based effluent limits (TBELs) for arsenic, selenium and nitrate/nitrite
as N on internal Outfall 004 (FGD wet scrubber wastewater to the ash settling basin), and Outfall 010
(combined seep outfall).The TBEL5 for arsenic and selenium were based on an evaluation of the effluent
data from the ash basin discharges from Belews Creek,Allen and Marshall Steam Stations.The limits for
nitrate/nitrite as N were based on the proposed EPA Steam Electric Effluent Limitation Guidelines (ELG)
because the Division did not have any long-term nitrate/nitrite data.
The NPDES regulations at 40 CFR §125.3(c)(2) require permit writers developing TBELs to consider the
following:

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• The appropriate technology for the category class of point sources of which the applicant is a
member, based on all available information.
• Any unique factors relating to the applicant.
The regulations also require that, in setting TBELs, the permit writer consider several specific factors
established in §125.3(d), to select a model treatment technology and derive effluent limitations on the
basis of that treatment technology.That process and the factors considered by the permit writer are the
same factors required to be considered by EPA in developing effluent guidelines. For establishing best
available technology(BAT) requirements for toxic and non-conventional pollutants, the following factors
must be considered:
— The age of equipment and facilities involved,
— Process employed,
— Engineering aspects of the application of various types of control techniques,
— Process changes,
— The cost of achieving such effluent reductions,and
— Non-water quality environmental impacts (including energy requirements).
Based on the information published by the Division, there was no indication that any of these factors
were considered in establishing the TBELs.
Furthermore, the Fact Sheet states "The existing federal regulations require the development of
Technology Based Effluent Limits (TBELs) for the parameters of concern." In Duke Energy' opinion,
however, the permit writer has the discretion to choose whether or not to impose BPJ limits. This
opinion is supported by a recent court ruling in Tennessee. The state court affirmed a 2013 decision of
the Tennessee Board of Water Quality,Oil,and Gas(the Board)holding that TVA's Bull Run Fossil Plant is
not required to have "BPJ" permit limits beyond what the 1982 Effluent Limitations Guidelines require.
The Board ruled against claims that more permit limits were required. The Board stated the permit
complies with the 1982 ELG rules, and "[b]ecause the 1982 ELG for power plants governs, a Best
Professional Judgment (BPJ) analysis was not required." The Board further stated, when EPA set the
1982 rules, EPA considered setting numeric limits for metals but decided not to because they were
"present in amounts too small to be effectively reduced"1.
In addition, it is stated in EPA's NPDES Permitting Manual (September 2010), regarding situations in
which case-by-case TBELs are necessary, "The permit writer should make sure that the pollutant of
concern is not already controlled by the effluent guidelines and was not considered by EPA when the
1 In the Matter of Tennessee Clean Water Network v. Tennessee Dept.of Environment and Conservation,Case No.
WPC10-0116(Tenn.Dept.of Env.and Conservation Dec. 17,2013).

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Agency developed the effluent guidelines.i1 Since EPA considered setting numeric limits for metals, the
Division is not obligated to establish TBELs for these parameters.
The Division's decision to propose TBELs on FGD wastewater, and seeps appears to be dictated by a
memorandum from James A. Hanlon to EPA Water Division Directors for its Regions: Memorandum,
James A. Hanlon to Water Division Directors, Regions 1-10, "National Pollutant Discharge Elimination
System (NPDES) Permitting of Wastewater Discharges from Flue Gas Desulfurization (FGD) and Coal
Combustion Residuals (CCR) Impoundments at Steam Electric Power Plants" (June 7, 2010). It is
important to note the Hanlon memorandum is guidance and not legally binding, as stated in Section VI
of the memo. Furthermore, the guidance does recommend establishing TBELs for FGD wastewater;
however, the guidance recommends establishing water quality based effluent limits (WQBELs), not
TBELs,for coal combustion leachate(i.e. ash basin seeps)2.
Mercury Limits at Outfall 002 and Outfall 010
The permit imposes TBELs for mercury at the combined Outfall 010 (combined ash basin seeps), and
Outfall 002 (ash basin discharges).These limits are based on the statewide mercury total maximum daily
load (TMDL).
Recommended Changes
1. Duke Energy requests a 5-year compliance schedule to comply with the mercury limit. With the
limits being newly proposed, a compliance schedule should be included to allow for the design,
evaluation, budget,and construction of a treatment system to meet the limits.
Outfall 004(treated FDG wet scrubber wastewater to ash settling basin'
As stated above, the permit establishes TBELs for arsenic, selenium, and nitrate/nitrite as N on the
internal Outfall 004 (treated FDG wet scrubber wastewater to ash settling basin). If the Division has
determined the FGD wastewater treatment systems at Belews Creek and Allen Steam Station represent
BAT for FGD wastewater,the limits should be based on the 95th and 99th percentiles of the effluent data
collected from the internal outfalls at Belews Creek (Outfall 002) and Allen (Outfall 005) Steam Stations.
For example,this analysis would yield the following TBELs for selenium3.
Parameter 95th percentile 99`h percentile
Selenium ((µg/L) 23 99
1 Refer to EPA's NPDES Permit Writers'Manual,September 2010,Section 5.2.3.2"Identifying the Need for Case-
by-Case TBELs"p.5-45—46.
2 Refer to Attachment B,"Water Quality-Based Effluent Limits Coal Combustion Waste Impoundments",of the
James Hanlon memorandum,June 7,2010.
3 The 95th and 99th percentiles were calculated from effluent data collected from the internal FGD outfall at Belews
Creek(Outfall 002)and Allen(Outfall 004)from April 2010 to March 2015.

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If this analysis resulted in a limitation less than 10 µg/L,the ability of the analytical method would need
to be evaluated to determine whether commercial laboratories could consistently detect the parameter
at or below the permit limit.
Due to the lack of long-term data,the Division based the nitrate/nitrite limits on the proposed ELG rule.
It should be noted, however, the nitrate/nitrite limits proposed in the ELG were only based on 10
observations (5 observations from both Belews Creek and Allen Steam Stations)'. These observations
were based on samples collected between June 2010 and January 2011 from the effluent immediately
following the FGD wastewater treatment systems. EPA, therefore, did not even have sufficient long-
term data to develop the limits for nitrate/nitrite in the proposed ELG rule.
In addition, the removal of nitrates/nitrites is only a co-benefit of the removal of selenium in the
anaerobic biological reactor and appears to only have been included in the proposed ELG rule to favor
anaerobic biological treatment over other selenium removal treatment technologies. In fact, EPA did not
derive limits for nitrates/nitrites for the other considered model technologies for the treatment of FGD
wastewater,such as chemical precipitation or vapor-compression evaporation.
These issues were the subject of numerous comments on the nitrate/nitrite limits in the proposed ELG
rule, in addition to the following:
— Analytical detection method: The method detection limit for nitrates/nitrites can be
affected by chlorides in the wastewater.This was not considered in the proposed ELG rule.
— Changes in the ORP can affect the ability of the treatment system to remove nitrate/nitrite.
— The analysis for the ELG rule did not consider removals for stations that have higher
selenium and nitrogen levels than Belews Creek and Allen.The treatment systems at Belews
Creek and Allen target selenium removal but not nitrogen removal, and both plants have
low selenium and nitrate/nitrite levels in their influent compared to the industry.
In addition, the arsenic and selenium limits are listed incorrectly for Outfall 004. Based on the Fact
Sheet,the limits should be listed as:
Monthly Average Daily Maximum
Selenium: 13.6µg/L 25.5 µg/L
Arsenic: 10.5 µg/L 14.5µg/L
Recommended Changes
2. Duke Energy requests the removal of TBELs from Outfall 004. EPA is under a court-order to
finalize the ELG rule by September 30, 2015. The final ELG rule is expected to impose limits on
1 Observations at Allen included the average of four 24-hour composite samples collected from 8/3/10-8/6/10,and
four 24-hr composite samples collected on 10/5/10, 11/1/10, 12/6/10 and 1/12/11.
Observations at Belews Creek included the average of four 24-hour composite samples collected from 6/8/10—
6/11/10,and four 24-hr composite samples collected on 10/6/10, 11/3/10, 12/8/10 and 1/17/11.

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the internal outfall of the discharge of FGD wastewater; however, EPA proposed three
treatment options for FGD wastewater with each option imposing different limitations. Given
the difficulty, cost and time in developing TBELs on a case-by-case basis in accordance with 40
CFR 125.3(d), it would be reasonable to remove the TBELs and incorporate the limitations and
the implementation schedule established under the final ELG rule. This would avoid any issues
with anti-backsliding and conflicts with North Carolina General Statute§ 150B-19.3.
3. If the Division is bound to impose TBELs for this permit issuance, Duke Energy requests the
inclusion of language in the permit allowing the TBELs to be revised, if less stringent limits are
imposed in the final ELG rule. This is especially prudent given the issues associated with the
development of the TBELs noted above (i.e. lack of adherence to 40 CFR 125.3(d)).The receiving
water body, Lake Norman, is in attainment for all parameters limited in the permit and the
reasonable potential analysis(RPA) concluded the discharges will not cause contravention of the
state water quality standards or EPA criteria; therefore, revising these limits to match the final
ELG rule will not impair the water quality or the designated use of the water body. To
accomplish this, Duke Energy recommends making the effective date of the TBELs to coincide
with the effective date of the final ELG rule with compliance required 4.5 years from the
effective date. It is anticipated the ELG rule will be effective in 15` quarter 2016. In addition,
Duke Energy requests an Outfall 004 (post-ELG rule) be created to serve as a "placeholder" to
incorporate the limitations in the final ELG rule into the permit.
4. If the TBELs are applied, Duke Energy requests the specific model technology used to derive the
TBELs that were applied to Outfall 004. In the event the model technology is installed and the
limits imposed are not achieved, Duke Energy would like to have the option of requesting a less
stringent limit as allowed under the Clean Water Act§402(o)2(E). If the Division has determined
the FGD wastewaters treatment systems at Belews Creek and Allen Steam Stations represents
BAT, the limits should be based on the 95`h and 99`h percentiles of the effluent data from the
internal FGD wastewater outfalls at Allen and Belews Creek Steam Stations. If this analysis
resulted in a limitation less than 10 µg/L, the ability of the analytical method would need to be
evaluated to determine whether commercial laboratories could consistently detect the
parameter at or below the permit limit.
Outfall 010 combined seen
Comments on the proposed limits for Arsenic,Selenium and Nitrate/Nitrite as N
Similar to Outfall 004, the permit establishes TBELs for arsenic, selenium, and nitrate/nitrite as N on
Outfall 010 (combined seep outfall). Again,the arsenic and selenium TBELs were based on an evaluation
of the effluent data from the ash basin discharges from Belews Creek,Allen and Marshall Steam Stations
and the limits for nitrate/nitrite as N were based on the proposed ELG rule.

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The proposed ELG rule classifies seeps from the ash basin as combustion residual leachate, specifically
impoundment leachatel. Under all the preferred options presented in the ELG rule, combustion residual
leachate would only be limited by total suspended solids (TSS) and oil and grease (O&G). In fact, EPA did
not even identify nitrate/nitrite or selenium as pollutants of concern for impoundment leachate in their
analysis for the proposed ELG rule2. Furthermore, the Hanlon memo describes a reasonable potential
approach for establishing limits for seeps based on water quality, not technology.
The nitrate/nitrite limits proposed in the ELG rule were based on data collected immediately following
the FGD wastewater treatment systems at Belews Creek and Allen Steam Stations and were not
associated with the ash basin discharge or ash basin seeps. The FGD treatment systems at Belews Creek
and Allen require denitrification, in order to remove selenium from the FGD wastewater stream. There
are, however, additional sources of nitrate/nitrite into the ash basin and potentially into the seeps that
are unrelated to the FGD wastewater discharge,such as:
— Goose droppings,
— Algae blooms due to nutrient inputs from stormwater runoff,and
— Input of sanitary waste treatment systems to the ash basin.
In addition, the nitrate/nitrite limits established for Outfalls 010 is extremely low and unnecessary. The
EPA 2013 Proposed Reissuance of the NPDES Multi-Sector General Permit for Stormwater Discharges
Associated with Industrial Activity proposed a benchmark for nitrate/nitrate of 0.68 mg/L, which is 5
times the monthly average limit in the draft permit.
Comments on the Implementation
The permit needs to state the methodology to calculate the concentration for the combined seeps to be
reported in the discharge monitoring reports (DMR).A flow-weighted average concentration is the most
appropriate methodology.This methodology is represented by the following formula.
Refer to Fed. Reg./Vol. 78, No. 110/Friday,June 7,2013/p. 34533§423.11(r) "The term combustion residual
leachate means leachate from landfills or surface impoundments containing residuals from the combustion of
fossil or fossil-derived fuel. Leachate includes liquid, including any suspended or dissolved constituents in the
liquid, that has percolated through or drained from waste or other materials placed in a landfill, or that pass
through the containment structure(e.g., bottom, dikes, berms)of a surface impoundment. Leachate also includes
the terms seepage,leak,and leakage,which are generally used in reference to leachate from an impoundment."
2 Refer to Section 6.7.3 of the Technical Development Document for the Proposed Effluent Limitations Guidelines
and Standards for the Steam Electric Power Generating Point Source Category, April 2013. Nitrites/nitrates as N
were not listed as a pollutant of concern for landfill leachate or impoundment leachate. Selenium was listed as a
pollutant of concern for landfill leachate but not impoundment leachate.

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C _El'(Ci x Qi)
En Qi
Where,
C= Flow-weighted average concentration of combined seeps.
n= Number of seeps sampled.
Ci=Concentration of the parameter for each seep in micrograms per liter.
Qi = Flow of each seep in liters.
Recommended Changes
5. Appendix A of the draft permit proposes that 2 identified seep locations be classified collectively
and permitted as Outfall 010 (combined seep outfall). Duke Energy will be further classifying
seeps into non-engineered seeps at locations where the seepage emerges from natural or
residual material and engineered seeps. Duke Energy requests the seeps listed and updated in
the Discharge Identification Plan (DIP) referenced in Appendix B be used as the official seep
identification with regards to official location and type (non-engineered seeps and engineered
seeps, i.e. toe drains). It would be anticipated that the seepage flows and water quality would
be inherently different at these two types of features. Duke Energy, therefore, believes it is
appropriate that the seeps be grouped into two outfalls: one for engineered seeps and one for
non-engineered seeps. The same permit limits and conditions applied to Outfall 010 should be
applied to engineered seeps.
6. Duke Energy requests the removal of the TBELs from Outfall 010 due to the fact the TBELs were
not developed in accordance with 40 CFR 125.3(d), the proposed ELG rule did not include limits
on arsenic, selenium, or nitrate/nitrate and insufficient data exists to develop TBELs. The data
used to derive the limits were based on other waste streams not specific to ash basin seeps;
therefore,the limits are not technically justified. Furthermore, the RPA was conducted at a flow
rate of 263 times the measured flow rate of the seeps.This added conservatism ensures the ash
basin seeps are not and will not adversely affect water quality. Additionally, the Division
assumed the seeps reach the surface water; however, to be considered a point source
discharge, the Clean Water Act requires a discernible, confined and discrete conveyance, in
which pollutants are discharged to navigable waters. The TBELs, therefore, should be removed
from the permit and doing so will not adversely affect water quality.
7. In lieu of TBELs, Duke Energy requests the Division to adopt a similar process as with new seep
identification to evaluate the constituent concentration and flow. If the concentration of any
parameter exceeds the concentrations in Table 1 of the permit or the total flow of all seeps is
determined to be in excess of 0.5 MGD, the Division should calculate reasonable potential to
determine if water quality based effluent limits (WQBELs) are necessary. If so, a formal
modification of the permit can be conducted to incorporate the WQBELs in the permit. This
approach would be consistent with the Hanlon memo.

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8. If the Division is bound to develop TBELs for seeps, Duke Energy requests a 5-year compliance
schedule. The permit states the limits can be met by installing a treatment system, re-routing
the discharge to the existing treatment system, or discontinuing the discharge. The Fact Sheet,
however, states it will be time-consuming and ineffective to re-route the seeps back to the ash
basin. Given these conflicting statements, a compliance schedule is necessary to evaluate,
budget,design and construct the treatment system or eliminate the discharge.
9. If the TBELs are imposed, Duke Energy requests the specific model technology used to derive
the TBELs that were applied to Outfall 010(combined seeps). In the event the model technology
is installed and the limits imposed are not achieved, Duke Energy would like to have the option
of requesting a less stringent limit as allowed under the Clean Water Act§402(o)2(E).
10. Duke Energy requests the inclusion of the methodology for determining the concentration to be
reported in the DMR for Outfall 010. Duke Energy recommends the following approach.
C _ En(Ci x Qi)
En Qi
Where,
C= Flow-weighted average concentration of combined seeps.
n= Number of seeps sampled.
Ci =Concentration of the parameter for each seep in micrograms per liter.
Qi= Flow of each seep in liters.
Sem Pollutant Analysis
The permit requires the facility to continue to implement the Plan for Identification of New Discharges
to determine if new seeps have emerged. New seeps identified must have the flow calculated and
sampled for parameters listed in the permit.
Comments on the identification of new seeps
The permit does not clearly define a seep or how the seep should be identified. It should be recognized
that a wet spot near the ash pond dike is not necessarily a seep from the ash basin and warrant the flow
to be calculated and samples collected. Seeps can emerge due to several factors that are
inconsequential to the ash basin,such as:
— Natural springs,
— Fluctuation in water level of the adjacent water body,
— Naturally formed wetlands,
— Intermittent and ephemeral streams, and

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— Stormwater drainage.
Furthermore, a discernible, confined and discrete conveyance from the seep to waters of the state or
U.S. should be present to classify the seep as a new discharge.
Comments on the Table 1 Parameters
The parameters listed in Table 1 of the permit include the daily maximum concentrations of the TBELs
for arsenic, selenium and nitrate/nitrite as N as opposed to multiplying the highest baseline seep
concentration by 10,as with the other parameters.As stated above,there is no technical justification for
these concentrations to be used as screening values. This is especially true for the nitrate/nitrite
screening value, which was based on the proposed ELG rule specific to FGD wastewater, not ash basin
discharge or discharges from ash basin seeps.
Comments on Notification
The notification requirements for newly identified seeps are not clear in the permit. It is stated in the
permit that newly identified seeps must be reported to the "Division of Water Resources within 5 days
of detection (location only, sampling results shall be submitted within 30 days of sampling) for
administrative inclusion in Appendix A." It is not clear whether the deadlines refer to calendar or
business days. The wording regarding the reporting of the location only and sampling results should
clearly indicate the deadlines. In addition, the permit is unclear on when samples must be collected
from the newly identified seep.
Recommended Changes
11. Duke Energy requests the inclusion of clarifying language in the permit defining a seep that
warrants further evaluation. Duke Energy requests the following clarifying language be included
in the permit:
"Seepage is considered to be the movement of wastewater from the ash basin
through the ash basin embankment, the embankment foundation, the
embankment abutments, through residual material in areas adjacent to the ash
basin, or through the bottom of the ash basin. Therefore, a seep is defined in
this permit as an expression of seepage at the ground surface above the
ordinary high water mark of any waters of the state. Only seeps that have the
presence of a discernible, confined and discrete conveyance to the surface
water will be considered a new seep warranting further evaluation of flow and
pollutant characterization."
12. Duke Energy requests the screening value of nitrate/nitrite removed from Table 1.There was no
baseline data collected and the screening concentration imposed is based on samples collected
from the discharge of FGD wastewater treatment systems, not ash basin discharge or ash basin

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seeps. Furthermore, there are natural sources of nitrate/nitrite that are unrelated to the ash
basin. Therefore, there is no technical justification for the inclusion of nitrate/nitrite as N in
Table 1.
13. Duke Energy requests the screening values for arsenic and selenium be revised to be 10 times
the baseline concentration as with the other parameters. Again, the screening values were
based on the TBELs imposed on Outfall 004. These values, however, were not derived in
accordance with 40 CFR 125.3(d)and were not based on data collected from ash basin seeps.
14. Duke Energy requests the inclusion of clarifying language on the notification requirements for
newly identified seeps.The following language is recommended:
"New seeps identified through the seep survey or otherwise discovered or
reported to the permittee shall have their flow calculated, and be sampled for
parameters indicated in Table 1. The location(s) of the seep shall be reported to
Division of Water Resources within 5 business days. Samples of the seep shall be
collected within 10 business days of identification and the sampling results shall
be submitted within 30 days of sampling for administrative inclusion in Appendix
A."
Dewatering
15. Duke Energy requests inclusion of clarifying language in the permit authorizing the removal of
free water above the settled ash layer including, but not limited to, decanting, controlled
pumping and/or normal operation. It is Duke Energy's understanding, based on conversations
with Division staff that the permit as drafted allows for the discharge of free water above the
settled ash layer in the ash basin by removal of stop logs, sections of riser and/or controlled
pumping through the permitted outfall flow path. As further discussed with Division staff, Duke
Energy will submit interstitial data to request authorization to conduct interstitial dewatering
activities. Interstitial water should be defined in the permit as entrapped water (i.e., water
occupying the pore space within the ash and below the ash surface). Interstitial wastewater
would be generated through mechanical movement of ash such as through dredging, and
excavating trenches within the ash and discharge would generally occur by controlled pumping.
Nonchemical Metal Cleaning Wastewater
The permit defines chemical metal cleaning wastewater and metal cleaning wastewater, but does not
define nonchemical metal cleaning wastewater. The permit only applies limits for chemical cleaning
wastewater to Outfall 002 (ash basin discharge), but no limits are applied for metal cleaning wastewater
or nonchemical metal cleaning wastewater.
16. Duke Energy requests the inclusion of language defining nonchemical metal cleaning
wastewater as low volume wastewater and only subject to the low volume wastewater limits of

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O&G and TSS. In the proposed ELG rule, EPA acknowledged the conflicting guidance given
historically on nonchemical metal cleaning wastewater and proposed to exempt stations from
the proposed revisions to the nonchemical metal cleaning limitation. Given the previous permits
for Marshall only applied limits for chemical metal cleaning, Marshall should qualify for this
exemption.
Duke Energy welcomes any further discussion on our comments or the draft permit. If you have any
questions, please contact Richard Baker at 704 382-7959 or at [e-mail].
Sincerel
—"J.--
HarK.Sideris -/'
Duke Energy
Senior Vice President, Environmental, Health &Safety