NC0004987_Draft WW Permit Fact Sheet-2015_20150306

NPDES Permit NC 0004987
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DENR/DWR
FACT SHEET FOR NPDES PERMIT DEVELOPMENT
NPDES No. NC0004987

Facility Information
Applicant/Facility Name: Duke Energy – Marshall Steam Station
Applicant Address: Water Management, Duke Energy, P.O. Box 1006, Charlotte, NC
28201
Facility Address: 8320 E. NC Highway 150, Terrell, NC 28682
Permitted Flow Not Limited
Type of Waste: 99.9% Industrial, 0.1% Domestic
Facility/Permit Status: Renewal
County: Catawba
Miscellaneous
Receiving Stream: Lake Norman Regional Office: Mooresville
Stream Classification: WS-IV & B CA USGS Topo Quad: Lake Norman North
303(d) Listed?: No Permit Writer: Sergei Chernikov, Ph.D.
Subbasin: 03-08-32 Date: October 27, 2014
Drainage Area (mi2): NA
Summer 7Q10 (cfs) Release (60 cfs)
Winter 7Q10 (cfs): NA
1Q10 (cfs):
IWC (%): 18

SUMMARY
This is a renewal of the NPDES wastewater permit for Marshall Steam Station. Duke Energy operates
Marshall Steam Station in Catawba County. The Station operates six outfalls. These outfalls are 001,
002, 002a, 002b, 003, and 004. The permitted outfalls are summarized below:

 Outfall 001 – Condenser Cooling Water (CCW) Units 1 – 4:
The CCW system is a once- through, non-contact cooling water system, which condenses steam
from the condensers and other selected heat exchangers. When the station is operating at full
power, it has a design capacity to pump 1463 MGD (1.016 MGPM) of cooling water through the
network of tubes that runs through the condenser and selected heat exchangers. The raw cooling
water is returned to the lake. No biocides or other chemic als are used in the condenser cooling
water. Units 1 and 2 operate two CCW pumps each while units 3 and 4 operate three pumps.

 Outfall 002 – Ash Basin:
The station ash basin accommodates flows from two yard-drain sumps, an ash removal system,
low volume wastes and non-point source stormwater. Low volume waste sources include, but are
not limited to: wastewater from wet scrubber air pollution control systems, ion exchange water
treatment system, water treatment evaporator blowdown, laboratory and sampling streams, boiler
blowdown, floor drains, and recirculating house service water systems. A sanitary waste treatment
system consists of an aerated basin that provides treatment with a 30 – day retention time and has
a total volume of 587,000 gallons. Effluent from the aerated basin is polished further through
additional residence time in the ash basin. The new system is designed for 6100 gpd (normal) and
13500 gpd (outage).

 Outfall 004 (internal outfall) – FGD system discharge into Ash Basin:
NPDES Permit NC 0004987
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In association with Clean Smokestacks legislation, Duke Energy installed a flue-gas desulfurization
(FGD) wet scrubber. This scrubber generates a wastewater needing treatment prior to discharge.
An internal outfall (004) has been established for the effluent from the FGD treatment system.
Internal outfall 004 will discharge to the ash settling basin which is currently permitted as outfall
002. FGD treatment system includes physical/chemical treatment and wetlands.

 Outfall 002a – Sump #1 Overflow:
This outfall discharges very infrequent overflows of yard sump number 1. The overflow generally
consists of the same wastewaters discharged by the ash basin. Late in 1998, the Division
developed a permitting strategy for these overflows. Analytical monitoring is required for flow,
pH, and TSS for all overflows lasting longer than an hour. When TSS is reported as greater than
100 mg/L, monitoring for iron is required. All overflows, regardless of time length, are reported
to the DWR regional office.

 Outfall 002b – Sump #2 Overflow:
This outfall discharges very infrequent overflows of yard sump number 2. The overflow generally
consists of the same wastewaters discharged by the ash basin.

 Outfall 003 – Unit 4 ID Fan Control House Cooling Water:
Once-through, non-contact cooling water is supplied to the Unit 4 induced draft (ID) fan motor
control-house equipment to remove excess heat. No chemicals are added to the once-through
raw lake water

 Outfall 010 – Combined Seeps.

Duke Energy Submitted Application dated October 9, 2014. The current permit expires April 30,
2015.

SEEPS- OUTFALL 010
The facility identified 2 unpermitted seeps from the ash settling basin. Seeps can be classified as either
engineered seeps (toe drains) from the earthen dam or non-engineered seeps that occur as wastewater
moves from the ash settling basin into groundwater and then into surface water, either directly or after
emerging on land. Engineered seeps can be captured and routed through a permitted outfall.

The non-engineered seeps represent a treatment system that has the potential to contaminate
groundwater and surface water. The original design and location of the impoundment are such that
wastewaster is not contained and directed to only engineered outfalls as the NPDES program
generally contemplates, but wastes are also being released to groundwater and emerging in the form of
seeps at the surface at diffuse and remote locations, with wastewater then flowing into surface waters
depending on site specific factors. Potential groundwater contamination is regulated through North
Carolina's 2L program. The CWA NPDES permitting program does not normally envision permitting
of uncontrolled releases from treatment systems; such releases are difficult to monitor and control,
and it is difficult to accurately predict their impact on water quality. Releases of this nature would
typically be addressed through an enforcement action requiring their elimination rather than
permitting.

The non-engineered seeps at this facility represent a unique circumstance, where the occurrence of the
seeps is attributable to an original pond design that will require long-term action to fully
address. Recent North Carolina legislation (Coal Ash Management Act of 2014) establishes a
framework for addressing all coal ash impoundments in the state to ensure that groundwater and
surface water are adequately protected through closure or other measures. However, action to close
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or otherwise address coal ash impoundments and their threats to surface waters and groundwater will
occur over a long term of those actions. In light of the long-term nature of action to fully address
these impoundments, the Division is proposing, as an interim measure, to ensure that all non-
engineered seeps are appropriately identified, monitored, and subject to protective effluent limits by
including the seep discharges as authorized discharges in the facility's NPDES permit. The permit
includes requirements to regularly inspect for new seeps, monitoring requirements for all identified
seeps, and applicable effluent limits which ensure that the seeps will not result in unacceptable impacts
to the receiving stream.

The facility identified 2 unpermitted seeps and conducted chemical analysis of the discharges. Only
one seep was flowing at the time of sampling. The flow volume was determined to be 0.0019 MGD.
For the purposes of permitting it was assumed that both seeps reach the surface water. The seeps are
not located on the walls of the dike.

The water in the seeps has percolated through the walls of the dike or through the bottom of the ash
pond. The soil in the dike or the bottom of the ash pond served as a filter, which removed some of
the pollutants from the wastewater . Consequently, most of the pollutants in the seep discharge have a
lower concentration of the constituents compared to the ash pond discharge. Therefore, pumping the
water from the seeps back to the ash pond is not likely to result in any additional pollutant removal.
Such pumping would also require construction activities that would disturb and damage sensitive
buffer areas. The construction activities would require 401 permits, which will create a substantial
delay with ash pond decommissioning and potentially jeopardize the deadlines for coal ash removal
established in the North Carolina Coal Ash Management Act of 2014. In addition, the combined seep
flow represents only 0.02 % of the ash pond discharge. Considering lower pollutant concentration for
most of the chemical compounds in the seep discharge, this discharge has an extremely low impact on
the receiving stream.

The maximum allowable parameter concentration for seeps was determined by multiplying the highest
concentration for a baseline seep data by 10. These values are substantially lower than the allowable
concentration determined by the Reasonable Potential Analysis for the combined seep flow. The
maximum allowable concentrations for Ni, Pb, and TDS were established at the levels of the water
quality standards.

ASH POND DAMS
Seepage through earthen dams is common and is an expected consequence of impounding water with
an earthen embankment. Even the tightest, best-compacted clays cannot prevent some water from
seeping through them. Seepage is not necessarily an indication that a dam has structural problems, but
should be kept in check through various engineering controls and regularly monitored for changes in
quantity or quality which, over time, may result in dam failure.

REASONABLE POTENTIAL ANALYSIS(RPA)-OUTFALL 002, OUTFALL 010
The Division conducted EPA-recommended analyses to determine the reasonable potential for
toxicants to be discharged at levels exceeding water quality standards/EPA criteria by this facility from
outfall 002 (Ash Pond). Calculations included: As, Be, Cd, Chlorides, F, Total Phenolic Compounds,
Cr, Cu, CN, Pb, Hg, Mo, Ni, Se, Ag, Zn, Fe, Al, B, and Mn (please see attached). The renewal
application listed 8.3 MGD (the water flow diagram) as a current flow. The analysis indicates no
reasonable potential to violate the surface water quality standards or EPA criteria.

The Division also considered data for other parameters of concern in the EPA Form 2C that the
facility submitted for the renewal. The majority of the parameters were not detected in the discharge.
The Division reviewed the following parameters that were detected in the discharge and have an
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applicable state standards or EPA criteria for Class WS-IV stream: phenols, Ba, and Co. All of these
parameters were well below the state standards/EPA criteria.

An RPA was also conducted for the combined flow from the seeps. Although, one seep was not
flowing at the time of the sampling it was assumed that it might discharge during the wet season.
Calculations included: As, Cd, Chlorides, Cr, Cu, F, Pb, Hg, Ni, Se Zn, Ba, Fe, and Mn (please see
attached). The analysis indicates no reasonable potential to violate the water quality standards or EPA
criteria. The flow volume for the first seep was measured at 0.0019 MGD. However, the flow of 0.5
MGD was used for the RPA to incorporate a safety factor, account for potential new seeps that might
emerge in the future or increase in flow volume at the existing seeps.

The RPA analysis indicates that existing discharges from the facility outfalls will not cause
contravention of the state water quality standards/ EPA criteria.

TECHNOLOGY BASED EFFLUENT LIMITS-OUTFALL 002, OUTFALL 004, AND OUTFALL 010
The existing federal regulations require development of Technology Based Effluent Limits (TBELs)
for the parameters of concern. Since the EPA has not promulgated any new Effluent Guidelines for
Power Plants since 1982, the Division has reviewed the performance of the existing coal-fired power
plants to establish TBELs: Marshall Steam Station, Belews Steam Station, and Allen Steam Station.
Two of these facilities (Belews and Allen) were used by EPA to establish the proposed Effluent
Guidelines for Power Plants. The Division focused on the following parameters: Total Arsenic, Total
Mercury, Total Selenium, and Nitrate/nitrite as N. These parameters are consistent with the
parameters selected by EPA in the proposed Effluent Guidelines. The Division agrees with the EPA
statement from the proposed Effluent Guidelines that justifies TBEL limitations for only four
pollutants of concern: “Effluent limits and monitoring for all pollutants of concern is not necessary to
ensure that the pollutants are adequately controlled because many of the pollutants originate from
similar sources, have similar treatabilities, and are removed by similar mechanisms. Because of this, it
may be sufficient to establish effluent limits for one pollutant as a surrogate or indicator pollutant that
ensures the removal of other pollutants of concern.”

Based on the review of the effluent data for the past 5 years the Division established the following
TBELs for the coal-fired power plants in North Carolina. The monthly average limits for Total
Arsenic and Total Selenium are based on 95th percentile of the effluent data, which is consistent with
the EPA methodology, and daily maximum limits for these constituents are based on the 99.9th
percentile of the effluent data. The Total Mercury limit is based on the Statewide Mercury TMDL
implementation strategy and was established by the Division previously. A statewide mercury TMDL
was developed to estimate the proportions of mercury contributions to water and fish from
wastewater discharges, in-state air sources, and out-of-state air sources, and to calculate appropriate
reductions needed. The TMDL was approved by EPA on 10/12/2012.

Total Arsenic – 10.5 µg/L (Monthly Average); 14.5 µg/L (Daily Maximum)
Total Selenium – 13.6 µg/L (Monthly Average); 25.5 µg/L (Daily Maximum)
Total Mercury – 47.0 ng/L (Monthly Average); 47.0 ng/L (Daily Maximum)

The Division does not have any long-term data for Nitrate/nitrite as N. Therefore, the limits for this
parameter are based on the proposed EPA Effluent Guidelines.

Nitrate/nitrite as N – 0.13 mg/L (Monthly Average); 0.17 mg/L (Daily Maximum)

Facility is allowed 4.5 years from the effective date of the permit to comply with the TBELs (Outfall
004 only). This time period is provided in order for the facility to budget, design, and construct the
treatment system. The compliance schedule is consistent with the proposed EPA Effluent Guidelines
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that require compliance with the TBELs “as soon as possible within the next permit cycle beginning
July 1, 2012”. Since the permit cycle is 5 years, the Effluent Guidelines will allow the facility to comply
with the TBELs by June 30, 2022. This permit has a more stringent requirements, the facility shall
comply with the TBELs by the end of 2019.

CWA SECTION 316(a) TEMPERATURE VARIANCE – OUTFALL 001
The facility has a temperature variance. In order to maintain the variance the facility has to conduct
annual biological and chemical monitoring of the receiving stream to demonstrate that it has a
balanced and indigenous macroinvertebrate and fish community. The latest BIP (balanced and
indigenous population) report was submitted to DWR in October of 2014. The DWR has reviewed
the report and concluded that Lake Norman near Marshall Steam Station has a balanced and
indigenous macroinvertebrate and fish community.

CWA SECTION 316(b)
The permittee shall comply with the Cooling Water Intake Structure Rule per 40 CFR 125.95. The
Division approved the facility request for an alternative schedule in accordance with 40 CFR
125.95(a)(2). The permittee shall submit all the materials required by the Rule with the next renewal
application.

INSTREAM MONITORING-OUTFALL 002
The permit required semi-annual upstream and downstream monitoring near the ash pond discharge.
The upstream site (Station 15.9) is approximately 1 mile upstream of the discharge and downstream
location (Station 14) is approximately 1 mile downstream of the discharge. These monitoring stations
have been established through the BIP monitoring program, which was required to maintain the
316(a) temperature variance. The monitored parameters are: As, Cd, Cr, Cu, Hg, Pb, Se, Zn, and Total
Dissolved Solids (TDS). The majority of the results are below detection level (Hg, As, Cd, Cr, Pb, Se),
the rest of the results are below water quality standards (Cu, Zn, TDS). Most parameters did not
demonstrate increase in the concentration at the monitoring stations below the discharge. The
exceptions are Zn, Cu, and TDS.

It is required that the monitoring of the instream stations will continue during the next permit cycle. It
is also required that the facility uses low level method 1631E for all Hg analysis.

FISH TISSUE MONITORING-NEAR OUTFALL 002
The permit required fish tissue monitoring for As, Se, and Hg near the ash pond discharge once every
5 years. This frequency is consistent with EPA guidance. Sunfish and bass tissues were analyzed for
these trace elements. The results were below action levels for Se and Hg (10.0 µg/g – Se, 0.40 µg/g –
Hg, NC) and screening value for As (1.20 – µg/g, EPA). These results are consistent with the previous
monitoring results.

TOXICITY TESTING-OUTFALL 002
Current Requirement: Outfall 002 – Chronic P/F @ 12% using Ceriodaphnia
Recommended Requirement: Outfall 002 – Chronic P/F @ 18% using Ceriodaphnia

This facility has passed all toxicity tests during the previous permit cycle, please see attached.
The Division will increase the Instream Waste Concentration from 12% to 18% due to the increased
wastewater flow.

COMPLIANCE SUMMARY
Notwithstanding the civil lawsuit filed for unauthorized discharges and groundwater
exceedances/violations, based on the monitoring required under the current version of the permit
there were no violations of effluent standards contained in the permit.
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PERMIT LIMITS DEVELOPMENT
 Outfall 001 – Condenser Cooling Water (CCW) Units 1 – 4:
Currently, only temperature is limited in this outfall. Summer and winter thermal limits have been
established in support of the 316(A) temperature variance issued by EPA in May of 1975.
 The temperature limits (Outfall 001) are based on the North Carolina water quality standards
(15A NCAC 2B .0200) and 316(a) Thermal Variance.
 Free Available Chlorine Limits (Outfall 001 and Outfall 003) were established in accordance
with 40 CFR 423.
 The limits for Oil and Grease and Total Suspended Solids (Outfall 002) are based on Best
Professional Judgment and are more stringent than prescribed in the 40 CFR 423.
 The pH limits (Outfall 002, 002A, and 002B) in the permit are based on the North Carolina
water quality standards (15A NCAC 2B .0200).
 The limits for Total Copper and Total Iron (Outfall 002) were established in accordance with
40 CFR 423.
 The turbidity limit in the permit (Outfall 002) is based on the North Carolina water quality
standards (15A NCAC 2B .0200).
 The Technology Based Effluent Limits for Total Arsenic, Total Mercury, Total Selenium, and
Nitrate/nitrite as N (Outfall 010) are based on the requirements of 40 CFR 125.3(a) , 40 CFR
122.44(a)(1); 40 CFR 125.3(c) and (d).
 The Technology Based Effluent Limits for Total Arsenic, Total Selenium, and Nitrate/nitrite
as N (Outfall 004) are based on the requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40
CFR 125.3(c) and (d).
 The Technology Based Effluent Limits for Total Mercury (Outfall 002) are based on the
requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d).
 The Whole Effluent Toxicity limit (Outfall 002) is based on the requirements of 15A NCAC
2B .0500.

PROPOSED CHANGES
 The Seep Outfall 010 (Please see A. (7.)) and Seep Pollutant Analysis Special Condition (Please
see A. (28.)) were added to the permit.
 The Appendix A and Appendix B were added to the permit.
 The Section 316(b) of CWA Special Condition was updated to reflect the new regulations.
 The turbidity limit was added to the permit (Outfall 002)to meet the state turbidity standard
per 15A NCAC 2B .0211(3) (k).
 The Technology Based Effluent Limits for Total Arsenic, Total Mercury, Total Selenium, and
Nitrate/nitrite as N were added to the permit (Outfall 010) and are based on the requirements
of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d).
 The Technology Based Effluent Limits for Total Arsenic, Total Selenium, and Nitrate/nitrite
as N were added to the permit (Outfall 004) and are based on the requirements of 40 CFR
125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d).
 The Technology Based Effluent Limits for Total Mercury were added to the permit (Outfall
002) and are based on the requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR
125.3(c) and (d).
 The water-quality based limits for Selenium were removed from the permit (Outfall 002) based
on the results of Reasonable Potential Analysis, and replaced with TBEL limits.
 Monitoring for Total Nickel was removed from the permit (Outfall 002) based on the results
of Reasonable Potential Analysis.
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 Monitoring for Chlorides was removed from the permit (Outfall 002) based on the results of
Reasonable Potential Analysis.
 Monitoring for Total Zinc was removed from the permit (Outfall 002) based on the results of
Reasonable Potential Analysis.
 Monitoring for Total Zinc was removed from the permit (Outfall 004) based on the results of
Reasonable Potential Analysis.
 Monitoring for Total Arsenic was added to the permit (Outfall 004) to evaluate treatment
efficiency of the FGD system.
 Monitoring for Total Mercury was added to the permit (Outfall 004) to evaluate treatment
efficiency of the FGD system.
 Proposed federal regulations require electronic submittal of all discharge monitoring reports
(DMRs) and specify that, if a state does not establish a system to receive such submittals, then
permittees must submit DMRs electronically to the Environmental Protection Agency (EPA).
The Division anticipates that these regulations will be adopted and is beginning
implementation.

The requirement to begin reporting discharge monitoring data electronically using the NC
DWR’s Electronic Discharge Monitoring Report (eDMR) internet application has been added
to the permit. (Please see Special Condition A. (29.)).
 The Applicable State Law Special Condition was added to the permit to meet the requirements
of Senate Bill 729 (Coal Ash Management Act, Please see Special Condition A. (30.)).

PROPOSED SCHEDULE
Draft Permit to Public Notice: March 6, 2015 (est.)
Permit Scheduled to Issue: July 27, 2015 (est.)

STATE CONTACT
If you have any questions on any of the above information or on the attached permit, please contact
Sergei Chernikov at [phone] or [e-mail].