NC0005088_Fact Sheet_20210618

DEPARTMENT OF ENVIRONMENTAL QUALITY
DIVISION OF WATER RESOURCES
FACT SHEET FOR NPDES PERMIT DEVELOPMENT
NPDES No. NC0005088
Facility Information
Applicant/Facility
Duke Energy Carolinas, LLC / Rogers Energy Complex
Applicant Address:
526 Church St., Charlotte, NC 28202
Facility Address:
573 Duke Power Road, Mooresboro, NC 28024
Permitted Flow (MGD):
Not limited
Type of Waste:
Industrial & domestic
Facility Classification:
II
Permit Status:
RenewalMajor Modification
County:
Rutherford & Cleveland
Miscellaneous
Receiving Stream:
Broad River/UT to Broad
River (Outfall 106)
State Grid:
G11NE
Stream Classification:
WS-IV
USGS Quad:
Chesnee
Drainage Area (mi2):
849 - Broad River
Basin/Subbasin:
Broad/03-08-02
Summer 7Q10 (cfs)
287 Broad River
303(d) Listed?
No
Winter 7Q10 (cfs):
440 Broad River
I3UC:
03050105
30Q2 (cfs)
635 Broad River
Regional Office:
Asheville
Average Flow (cfs):
1460 Broad River
Permit Writer:
Teresa
RodriguczSergei
Chernikov, Ph.D.
IWC (%):
7.7 -(002)
3.1 (005)
Date:
4/3/20183/30/202
0
SUMMARY
Duke Energy Carolinas operates the Rogers Energy Complex (REC); formerly known as Cliffside
Steam Station; a two -unit coal fired steam electric generating facility. Units 1-4 have been removed
from service. The station now operates only two units; Units 5 and 6. The total combined output is
1500 megawatts. Each unit has a Flue Gas Desulfurization (FGD) system. The site has an industrial
landfill for combustion byproducts where fly ash, bottom ash, gypsum and WWTP sludge is
deposited.
Water for cooling is withdrawn from the Broad River. Both units use cooling towers for heat
dissipation. Blowdown from Unit 5 is discharged to the ash basin. Blowdown from Unit 6 can be used
in the unit's make up water or discharged to the ash basin.
The receiving water is the Broad River, class WS-IV waters in the Broad River Basin. Previous
permits had this section classified as C. The correct classification is WS-IV and it will be modified in
the permit.
Fact Sheet
NPDES NC0005088 Rent i lMajor Mod
Page 1

REC is subject to EPA effluent guideline limits per 40 CFR 423 - Steam Electric Power Generating
Point Source Category. The facility is also subject to the Cooling Water Intake Structures Rules (40
CFR 125) effective October 14, 2014 and to the North Carolina Senate Bill 729 - Coal Ash Management
Act.
This permit is being modified to make the following changes:
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1). To adjust the Technology Based Effluent Limits for Total Arsenic, Total Mercury, Total Selenium,
and Nitrate/nitrite as N for Internal Outfall 004 (FGD wastewater) in accordance with updated 40 - - l Formatted: Font: Book Antigua, 11 pt
CFR 423.13(g)(1)(i). Please see the table below for details.
Pollutant
Existing monthly average - daily
Modified monthly average - daily.
maximum limit
maximum limit
Arsenic
8.0 µg/L -11.0 µg/L
8.0 µg/L -18.0 jig/ L
Selenium
12.0 µg/ L - 23.0 µg/ L
29.0 µg/ L - 70.0 µg/ L
Mercury
356.0 µg/ L - 788.0 µg/ L
34.0 µg/ L -103.0 µg/ L
Nitrate/Nitrite
4.4 mg/L -17.0 mg/L
3.0 mg/L - 4.0 mg/L
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2). To extend compliance schedule for FGD wastewater from 12/31/2021 to 6/30/2022 This time is-- - -
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needed to properly initiate biological treatment system and adjust physical/chemical equipment for
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consistent performance. The request is based on the experience with the similar systems at Roxboro,
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Marshall, and Allen facilities.
3). To reduce instream temperature monitoring frequency at Outfall 005 from Weekly to Quarterly.- - - l Formatted: Font: Book Antigua, 11 pt
Currently, the facility operates cooling towers on the remaining two power generating units. The
recent report demonstrated that the existing conditions defining the temperature mixing zone and
effluent temperature limits are being met. Furthermore, the facility is complying with the state
temperature standard and frequent instream monitoring is no longer necessary.
All the remaining terms and conditions of the permit remain unchanged.
PROPOSED SCHEDULE
Draft Permit to Public Notice:
Permit Scheduled to Issue:
February 23,2021 (est.)
A_pril 2, 2021 (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].
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1
CHANGES IN THE FINAL MODIFICATIOIN
• :The optimization requirement was added to the FGD Effluent Page (Internal Outfall 004) in --(Formatted: Font: Book Antigua, 11 pt 3
response to the SELC comment.
• The Deadline Extension for the FGD wastewater (Internal Outfall 004) was reduced from 6
months to 3 months in response to the SELC comment.
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Outfall Descriptions:
Fact Sheet
NPDES NC0005088 Rent i lMajor Mod
Page 2
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The ash basin receives wastewaters collected in the Yard Drainage Basin (effluent from the domestic
WWTP, cooling tower blowdown from Unit 5, landfill 1 achatc, floor drains, treated FGD wet
scrubber water, limestone unloading and storage ar a, and stormwater), sluiced ash, cooling tower
blowdown from Unit 6, equipment backwashes, boiler blowdown, drainage from recirculating
cooling systems, demineralizing resin, cooling water from h at exchangers, rinse water from
limestone unloading and storage area, stormwater, low volume waste including flight conveyor
quench water overflow), and miscellaneous waste streams. This outfall discharges to the Broad
River.
This outfall was closed in 2016. This was an emergency outfall from the yard drainage basin.
If the wastewater from the FGD system is not used in Unit 6 it is treated in the FGD WWTS which
consists of equalization tank, reaction tank, flocculating clarifier, and gravity filters. The effluent is
discharged to the Yard Drainage Basin. A new treatment system will be installed for the FGD
wastewaters. The effluent of the treatment system will be combined with the effluent from
proposed outfall 005 before discharging to the Broad River.
Proposed Outfalls:
Outfall-005—New--Wastewater-Treatment-System
A new tr atment system will be installed to tr at wastewaters from the holding basin effluent
(RO reject, stormwater and Unit 6 sanitary system), Unit 6 cooling tower blowdown, landfill
1 achate, Unit 6 process sump (mechanical drag chain overflow, and low volume waste including
flight conveyor quench water overflow) Unit 5 proce:r .,ump (sanitary sy.,tem, low volume wa.,tes,
mechanical drag chain overflow and cooling tower blowdown), and ash basin
dewatering/ decanting. The FGD WWTS di -charge (Internal Outfall 004) and heat exchanger non
contact cooling water will be combined with the discharge from the WWTS before discharge to the
Broad River. The tr atment system will be a physical/chemical tr atment system with flow
equalization, pH neutralization, coagulation and flocculation, and filters. This outfall will discharge
to the Broad River.
This will be an emergency outfall from the Basement Basin if a significant rain event overflows the
system. An existing structure will be used as a holding cell for process wastewater, tr ated sanitary
wa.,tewater and .,tormwater that currently go to the P 5 yard ba.,in. The effluent from this holding
cell will be pumped to the ash basin during normal operations. When the new WWTS starts
operations the holding cell will receive stormwater runoff from Unit 6, RO reject wastewater, Unit 6
treated sanitary wastewater and proce:r and stormwater from Unit 5. Effluent will be pumped to
the new WWTS. An auxiliary basin will hold excess water during storm events. The emergency
outfall will discharge to the Broad River.
This will be an emergency outfall from a new holding ba.,in if a .,ignificant rain event overflows the
system. This holding basin will receive stormwater, coal pile runoff, gypsum pile runoff, limestone
pile runoff and flows from the holding cell auxiliary basin (stormwater runoff from Unit 6, RO
reject wastewater, treated sanitary wastewater and proce:r and stormwater from Unit 5). The
effluent from this holding basin will be pumped to the new WWTS. The emergency overflow will
discharge to the Broad River.
Fact Sheet
NPDES NC0005088 Renew lMajor Mod
Page 3

Outfalls 104 discharge seepage from the ash basin into the Broad River and Outfall 106 discharges,
seepage to an UT to the Broad River. A Special Order by ConGcnt ("Special Order"), EMC SOC 17
009, also addresses Outfalls 104 and 106. In this Special Order, these outfalls are called "engineered
seeps." Duke Energy shall follow the requirements of the Special Order with regard to these
engineered seeps, including but not limited to the requirement that if any of the engineered seeps
are not di -positioned (as described in EMC SOC 17 009 § 2(c)(3)) following decanting of the ash
basins (as described in EMC SOC 17 009 § 1(a)) at Rogers Energy Complex, Duke Energy shall
submit an amendment to its groundwater Corrective Action Plan and/or Closure Plan for the
Rogers Energy Complex describing how any of the non dicpocitioned engineered seeps will be
remediated in a manner sufficient to protect public h alth, safety, and welfare, the environment,
and natural resources (as described in EMC SOC 17 009 § 2(d))
COMPLIANCE REVIEW/PROPOSED ACTIONS
This outfall is subject to the Effluent Limitations Guidelines (ELG) in Table 1.
Table 1. ELG Outfall 002
Pollutant v
(DM}
Monthly lEr ELC
Alai
50 mg/I
30 mg/I
40 CFR 423(b)(4) (monthly
423(b) is,) (daily max)
Oil & Crease
20 mg/I
15 mg/I
40 CFR 423.12 (b) (4)
pH
6 to 9 SU
40 CFR 423.12 (b) (1)
As per 40 CFR 423.13 (h) (1) (i) and (k) (1) (i) bottom ash and fly ash transport water shall not be
discharged, compliance with this section shall be as soon as po^.,ible beginning on November 1,
2018 for fly ash and November 1, 2020 for bottom ash, but no later than December 31, 2023. Duke
has submitted the following proposed schedule for meeting the rule:
Bottom a.,h: An underneath the boiler mechanical drag .,y.,tem will be in.,talled and will be
operational by November 1, 2020. This technology will not generate bottom ash.
Fly ash: dry fly ash is handled dry at this facility.
DMR review:
DMR data were review for the period of January 2011 to April 2016. There were no violations of
permit limits.
Table 2. DMR Summary Outfall 002
Parameter
Average T
Maximum
Minimum
Flow
6.753
29,8
0.40
(MGD)
TSS (mg/1)
6,8
18
< 5
Temperature °F
66,4
883
45.5
O&C (mg/1)
<5
<5
<5
Total Nitrogen (mg/1)
0,93
1.5
0,54
Total Phosphorus
(mg/1)
0.09
049
0
(S.U.)
7.1
8,6
64
pH
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NPDES NC0005088 Renew lMajor Mod
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RPA Outfall 002:
The need for toxicant limits is based upon a demonstration of r asonable potential to exceed water
quality standards, a Gtatis,tical evaluation that is conducted during every permit renewal utilizing
the mot recent effluent data for each outfall. The RPA is conducted in accordance with 40 CFR
122.44 (d) (i). The NC RPA procedure utilizes the following: 1) 95% Confidence Level/95%
Probability; 2) a:rumption of zero background; 3) use of detection limit for "les,., than" values;
and 4) str amflows used for dilution cons,ideration based on 15A NCAC 2B.0206. Effective April 6,
2016, NC began implementation of dissolved metals criteria in the RPA process in accordance with
guidance titled NPDES Implementation of Instream Dissolved Metals Standards, dated June 10, 2016.
The current permit included monitoring for various metals to evaluate the impact from FCD
wastewaters. A reasonable potential analysis was performed for arsenic, cadmium, chlorides,
sulfates and thallium. A r asonable potential analysis was conducted on effluent toxicant data
collected between January 2011 and May 2016. Pollutants of concern for the decant wastewater
included toxicants with positive detections and a^.,ociated water quality standards/criteria. None
of the parameters presented reasonable potential.
TOXICITY TESTING:
Current Requirement: Outfall 002 Chronic P/F @ 7.14% using Ceriodaphnia
Recommended Requirement: Outfall 002 Chronic P/F @ 7.7% using Ceriodaphnia
Instr am waste concentration is based on the maximum monthly flow during the previous permit
eyele,
This facility has passed 21 out of 21 toxicity tests during previous permit cycle.
Mercury Evaluation:
Table 3. Mercury Data Evaluation
2011
2012
2013
2014
2015
tt of Samples -
18
1-2
42
13
1-2
Annual Average, ng/L
3.1
1.8
1.7
1.5
14
Maximum Value, ng/L
11.30
3.50
340
3,90
2.30
TBEL, ng/L -
47
WQBEL, L
159.1
ng/
Annual averages are below the TBEL and WQBEL, no limit is required for mercury.
Table 1. Monitoring Requirements/Propo.,cd Changes Outfall 002
Parameter
Flow
T-S
requirements
I
Monitor
Monitor
30 mg/1 MA
100 mg/1 DM
Changca
No changes
Daily maximum
for TSS changed
to 50 mg/L
Basin
15A NCAC 2B.0505
MA 40 CFR 423.12(b)(4)
DM 10 CFn 123 (b) (s,) coat p:te raise ff
is discharged through this outfall
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Oil & Crease
15 mg/1 MA
20 mg/1 DM
No changes,
40 CFR 423.12(b)(4)
Total iron
1 mg/1 MA
1 mg/1 DM
No changes
40 CFR 423.12(b)(5)
Only monitored during discharge of
metal cleaning wastes
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NPDES NC0005088 Renewa Major Mod
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Total cooper
Total chromium
Total zinc
1 mg/1 MA
1 mg/1 DM
Monitoring
101 µg/1 MA
111 µg/ 1 DM
0.2 mg/L MA
0.2 mg/L DM
1.0 mg/L MA
1.0 mg/L DM
State WQ standards,15A NCAC 2B
.0200. Only monitored during
discharge of metal cl aning wastes.
Water quality limits more stringent
than ELC.
40 CFR 423.13 (d)(1)
40 CFR 423.13 (d)(1)
Total nickel,
total silver
r�r,.,n�o ester ooeeky
Eliminate
monitoring
Total cadmium
Monitor -weekly
Monitor Monthly
Total selenium,
Total arsenic
Total thallium,
total lead
Monthly
monitoring
Monthly
monitoring
No requirement
Meniter- Mentlly
Meniter- Monthly
Monitor Monthly
Previous permit had monitoring to •
evaluate impact from FCD. There is no
ELC for these parameters and no
reasonable potential to exceed wqs.
Maximum predicted concentration
greater than 50% of the allowable
Pollutant of concern for ash.
Total mercury
Monitor
monthly
No changes,
Pollutant of concern for ash.
Reeasonable potential to exceed EPA .-
Pollutant of concern for ash.
Total Hardness
BOD5
Fecal Coliform
No requirement
No requirement
No requirement
Quarterly
monitoring
30 mg/ L MA
45 mg/ L DM
200/100 mL MA
400/100 mL DM
Collect data for RPA
Outfall discharges tr ated domestic
wastes
Outfall discharges treated domestic
wastes
Total Nitrogen
Total
Phosphorus
pH
Quarterly
Monitoring
6 to 9 SU
No changes,
No changes,
State WQ standards,15A NCAC 2B
00
To meet the requirements of the Coal Ash Management Act of 2014, the facility needs to dewater
the ash pond by removing the interstitial water and excavate the ash to deposit it in landfills. The
facility's highest discharge rate from the dewatering process will be 1 MCD. The facility submitted
data for the standing surface water in the ash pond, interstitial water in the ash, and interstitial ash
water that was tr ated by filters of various sizes. To introduce a margin of safety the highest
m asured concentration of a parameter was used in the RPA. RPA analysis was done for arsenic,
cadmium, chlorides, aluminum, TDS, copper, fluoride, lead, molybdenum, nickel, selenium, zinc,
barium, .,ulfates and thallium. None of the parameters .,howed rea.,onable potential.
This outfall is subject to the ELC in Table 5. These are new limitations promulgated November 3,
2015. The permitter has to meet the limitations as soon as po^.,ible beginning November 1, 2020 but
no later than December 31, 2023.
Fact Sheet
NPDES NC0005088 Renew lMajor Mod
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Table 5. ELG Outfall 001
Pollutant
Monthly
ELG
PH
TSS
6 to 9 SU
100 mg/I
30 mg/I
40 CFR 423.12 (b) (1)
40 CFR 423.12 (b) (11)
Oil and grease
Total Arsenic
Total Mercury
20 mg/I
11 µg/1
788 ng/I
15 mg/I
356 ng/I
40 CFR 423.12 (b) (11)
40 CFR 423.13 (g) (1) (i)
40 CFR 423.13 (g) (1) (i)
Total Selenium
Nitrate/ nitrite
23 µg/l
17 mg/I
12 µg/1
4.1 mg/I
40 CFR 423.13 (g) (1) (i)
40 CFR 123.13 (g) (1) (i)
The new rule establishes compliance dates for the new limitations. Permitter must meet limits as
coon as pos.,ible beginning on November 1, 2020 but no later than December 31, 2023. Duke
requc.,ted a compliance .,chedule to evaluate, in.,tall and te.,t a new treatment .,ystem with a
propo.,ed compliance date of December 31, 2023. Duke estimates 22 months for technology
evaluation, engineering design, and citing. 27 months are estimated for procurement, 16 for
construction and 15 for startup and optimization. The permit will require compliance by December
31, 2023.
Table 6. Monitoring Requirements/Proposed Changes Outfall 004
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Monitoring
requirements
Changes
Flew
TSS
Oil and grease
Total Arsenic
Total Cadmium
Monitor
Monitor
Ne-Monitor
Monitor
Monitor
No changes
Limits of 30 mg/1 (MA)
and 100 mg/1 (DM)
Limits of 15 mg/1 (MA)
and 20 mg/1 (DM)
Add limits of 11 µg/I
daily max and 8 µg/I
monthly average
Remove monitoring
Total
Chromium
Monitor
Remove monitoring
Chloride
Monitor
Remove monitoring
15A NCAC 2B.0505
40 CFR 423.13 (b) (11)
40 CFR 423.13 (b) (11)
40 CFR 423.13 (g) (1) (i)
Internal outfall, not a parameter of
concern.
Internal outfall, not a parameter of .-
concern.
Internal outfall, not a parameter of
Total Mercury
Total Nickel
Monitor
Monitor
Add limits of 788 ng/1
daily max and 356 ng/1
monthly average.
Remove monitoring
40 CFR 423.13 (g) (1) (i)
Internal outfall, not a parameter of
Total Selenium
Total Silver
Monitor
Monitor
Add limits of 23 µg/1
daily max and 12 µg/1
monthly average
Rcmovc monitoring
40 CFR 423.13 (g) (1) (i)
Internal outfall, not a parameter of
Total Zinc
Monitor
Remove monitoring
Internal outfall, not a parameter of
concern.
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Nitrate/ Nitrite
No
monitoring
Add limits of 17 mg/1
daily max and 4.4 mg/1
monthly average
40 CFR 423.13 (g) (1) (i)
Proposed Outfalls:
n.ttfall 005 rr...., Vast,... ate Tr .t en Syst.. nA/ LS)
This new outfall will discharge tr ated process wastewaters from the plant including low volume
wastes and cooling tower blowdown. This tr atment system is expected to be in place by the end of
2018. Proposed limits and monitoring requirements are described in Table 7.
Table 7. Monitoring Requirements/Limits Proposed Outfall 005
Parameter
Flow
recittiremen1s
Monitor
Basis
15A NCAC 2B.0505
Oil & Crease
30 mg/L MA
50 mg/L DM
15 mg/L MA
20 mg/L DM
MA 40 CFR 423.12(b)(4)
DM 40 CFR 423 (b) (9) coal pile runoff is
discharged through this outfall
40 CFR 423.12(b)(4)
Total lion
1 mg/L MA
1 mg/L DM
40 CFR 423.13 (b) (5)
Parameter only monitored during discharge
of metal cleaning wastes
Total Cooper
251 µg/L MA
272 µg/L DM
State WQ standards, 15A NCAC 2B .0200.
Parameters only monitored during
discharge of metal cleaning wastes.
Total Chromium
0.2 mg/L MA
0.2 mg/L DM
40 CFR 423.13 (d)(1)
Total Zinc
Total Hardness
Total Nitrogen
Total Phosphorus
pH
BOD5
Fecal Coliform
1.0 mg/L MA
1.0 mg/L DM
Quarterly
Monitoring
Quarterly
Monitoring
6 to 9 SU
30 mg/L MA
45 mg/L DM
200/100 mL MA
400/100 mL DM
40 CFR 423.13 (d)(1)
Collect data for RPJ\
State WQ standards,15A NCAC 2B .0200
Outfall discharges tr ated domestic wastes
Outfall discharges treated domestic wastes
THE
Whole Effluent
Toxicity
Total Cadmium,
Total Mercury,
Total Selenium,
Total Arsenic,
Total Thallium
28 µg/ L DM
Chronic toxicity
test at 3.14°,G
State WQ standards,15A NCAC 2B .0200
State WQ standards, 15A NCAC 2B .0200
Only applicable if the decanting and
dewatering is discharged through the
WWTS
Autf-a11-002$
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NPDES NC0005088 Renew lMajor Mod
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This outfall will discharge from the Basement Basin only during excessive rain events (100 yr 24 hr
rain). The holding cell will collect stormwater runoff from Unit 6, RO reject wastewater, tr ated
sanitary wastewater and proce:r and stormwater from Unit 5.
Table 8. Monitoring Requirements/Limits Proposed Outfall 002B
Parameter
Flow
Limits/A4enitering
requirements
Monitor
Basin
15A NCAC 2B.0505
w
TSS
Oil & Crease
30 mg/L MA
100 mg/L DM
15 mg/L MA
20 mg/L DM
40 CFR 423.12(b)(3)
40 CFR 423.12(b)(4)
Total iron
1 mg/L MA
1 mg/L DM
40 CFR 423.13 (b) (5)
Parameter only monitored during discharge
of metal cleaning wastes
Total cooper
pH
BOD5
Fecal Coliform
251 µg/ L MA
272 µg/ L DM
6 to 9 SU
30 mg/L MA
45 mg/L DM
200/100 mL MA
400/100 mL DM
State WQ standards, 15A NCAC 2B .0200.
Parameters only monitored during
discharge of metal cleaning wastes.
State WQ standards, 15A NCAC 2B .0200
Outfall discharges treated domestic wastes
Outfall discharges treated domestic wastes
Whole Effluent
Toxicity
Acute episodic test
State WQ standards, 15A NCAC 2B .0200
And-all-002E
This outfall will discharge from the proposed Holding Basin only during excessive rain events (100
yr 24 hr rain). The holding cell will collect stormwater, coal pile runoff, gypsum pile runoff and
lime.,tone .,torage area runoff and flows from the Basement Ba.,in auxiliary ba.,in (.,tormwater
runoff from Unit 6, RO reject wastewater, treated sanitary wastewater and prose.,., and .,tormwater
from Unit 5).
Table 9. Monitoring Requirements/Limits Proposed Outfall 002C
Parameter
LimitsiAlenitering
requirement
Basis
Flow
Monitor
15A NCAC 2B.0505
TSS
Oil & Crease
Total lion
Total Cooper
30 mg/L MA
50 mg/L DM
15 mg/L MA
20 mg/L DM
1 mg/L MA
1 mg/L DM
102 µg/ L MA
111 µg/ L DM
MA 40 CFR 423.12(b)(4)
DM 40 CFR 423 (b) (9) coal pile runoff is
discharged through this outfall
40 CFR 423.12(b)(4)
40 CFR 423.13 (b) (5)
Parameter only monitored during discharge
of metal cleaning wastes
State WQ standards, 15A NCAC 2B .0200.
Parameters only monitored during
discharge of metal cleaning wastes.
pH
BOD5
6 to 9 SU
30 mg/L MA
State WQ standards, 15A NCAC 2B .0200
Outfall discharges treated domestic wastes
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45 mg/L DM
Fecal Coliform
200/100 mL MA
400/100 mL DM
Outfall discharges tr ated domestic wastes
Whole Effluent
Toxicity
Acute episodic test
State WQ standards, 15A NCAC 2B .0200
Outcans Inn and 106 ..trusted ut alla.
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Two constructed seeps, Outfalls 104 and 106, discharge from the ash basin into the Broad River .-
(104) and an UT to the Broad River (106). A Special Order by Consent ("Special Order"), EMC SOC
17 009, alto addres.,es Outfalls 104 and 106. In this Special Order, these outfalls are called
"engineered seeps." Duke Energy shall follow the requirements of the Special Order with regard
to these engineered seeps, including but not limited to the requirement that if any of the engineered
seeps arc not di.,positioncd (as described in EMC SOC 17 009 § 2(c)(3)) following decanting of the
ash basins (as described in EMC SOC 17 009 § 1(a)) at Rogers Energy Complex, Duke Energy shall
Rogers Energy Complex Station describing how any of the non dispositioned engineered seeps will
be remediated in a manner sufficient to protect public h alth, safety, and welfare, the environment,
and natural re.,ources (as described in EMC SOC 17 009 § 2(d)1
Table 10. Toc drains Coordinates and As.,igned Outfall Numbers
ID
Latitude
Longitude
Outfall
number
S1
'O?"
104
35°13'3.5"
A'°^
S 6
13' 6.3
44' 53.7"
106
35°
81°
RPA Seeps
A RPA was conducted for the seeps. RPA was conducted for total arsenic, cadmium, chlorides, total
chromium, total copper, total l ad, total boron, total mercury, total molybdenum, total nickel,
was 0.032 mgd. The maximum flow recorded for toe drain 106 was 0.164 mgd. The flows were
multiplied by a factor of safety of 10 for the RPA. Ba.,ed on the RPA Outfall 106 include limits for
total aluminum and total din olved .,olids.
These outfalls will have monitoring requirements for fluoride, total mercury, total barium, total
iron, total manganese, total zinc, total arsenic, total cadmium, total chromium, total copper, total
1 ad, total nickel, and total selenium, chlorides, nitrate/nitrite, total d.'.,olved solids, hardness,
turbidity, conductivity and limits as described in Table 11.
Table 11. Monitoring Requirements Proposed Toc Drain Outfalls Monitoring:
Parameter
Flow
pH
TSS
Oil & Cr ase
reEtulrementsUtnitsiMeR4tefiftgdiillt
Monitor
6.0 to 9.0 S.U.
30 mg/1 MA
100 mg/1 DM
15 mg/1 MA
20 mg/1 DM
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316(b) REQUIREMENTS
The permitter shall comply with the Cooling Water Intake Structure Rule per 40 CFR 125.95. The
Division approved the facility reque.,t for an alternative .,chedule in accordance with 40 CFR
125.95(a)(2). The permitter shall submit all the materials required by the Rule with the next renewal
application.
The rule requires the Director to establish interim BTA requirements in the permit on a site specific
basis based on the Director's best professional judgment in accordance with §125.90(b) and 40 CFR
401.14. The existing closed cycle system at REC is one of the pre approved compliance alternatives
for impingement in accordance with §125.94(c)(1). EPA also considered it as a pre approved BTA
for entrainment, but excluded it from the rule due to the cost concerns. Based on this information
the DEQ has determined that the existing closed cycle cooling system meets the requirements for an
interim BTA.
316 (a) CWA
The thermal variance and temperature mixing zone once included in the permit for outfall 002 is no
longer applicable. The special conditions referring to the variance and mixing zone were eliminated.
FISH TISSUE STUDIES
The facility performed fish tissue analysis for arsenic, selenium and mercury as required by the
permit. The Division reviewed the information and concluded that all the fish tissue levels reported
are below the Department of H alth screening values.
INSTREAM MONITORING
The current permit did not require instream monitoring. The proposed permit will require monthly
up.,trctiam and down.,tream monitoring for total ar.,enic, total .,clenium, total mercury, total
total hardness (as CaCO3), temperature, turbidity, and total dissolved solids (TDS).
SUMMARY OF CHANGES:
1. Eliminated outfall 002A since it has been shut down.
2. Added effluent pages for outfalls 002B, 002C and 005.
3. A separate effluent page for the dewatering of the ash ponds (Outfall 002) was added to the
permit. PI ase see Special Condition A. (2)
4. Special Condition A. (24) Section 316(b) of CWA was updated to reflect the new regulations.
5. Special Condition A. (8) Section 316(a) Thermal Variance in the old permit was eliminated
since the facility no longer requires a thermal variance.
6. Special Condition A. (26) Ash Pond Closure was added to the permit to facilitate the
decommissioning of the ash ponds.
7. Special Condition A. (13) Instr am Monitoring was added to the permit to monitor the
impact of the discharges on the receiving str am.
8. Special Condition A. (25) Applicable State Law was added to the permit to meet the
requirements of Senate Bill 729 (Coal Ash Management Act).
9. Special Condition A. (23) Domestic Wastewater Treatment Plant was added to the permit to
as.,ure compliance with the 40 CFR 133.102.
10. Special Condition A. (28) Electronic Reporting was added to the permit describing
requirements for electronic reporting of DMRs. Starting December 21, 2016, federal regulations
require electronic submittal of all discharge monitoring reports (DMRs) and specify that, if a state
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does not establish a system to receive such submittals, then permittees must submit DMRs
electronically to the Environmental Protection Agency (EPA).
11. Special Condition A. (29) Notification of Start up Outfall 005 was added to the permit.
Changes to the September 21, 2016 draft permit:
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1. St am Electric ELG In September 2017, the EPA delayed the implementation date for .- - - Formatted: Normal, Right: 0", No bullets or numbering
effluent guidelines for the St am Electric Power Generating Point Source Category to allow time to
revise some of the BAT limitations for FGD wastewaters and bottom ash transport water. The
arlicst compliance date for the FGD wastewater in §123.13(g)(1)(i) and for the bottom ash transport
water in §123.13(k)(1)(i) were delayed from November 1, 2018 to November 1, 2020. A rcopener was,
added to outfall 004 .,pacifying that the Division may reopen the permit to implement limits a.,
revised in the ELC.,.
2. Seeps Discharges Effluent Limitations and Monitoring Requirements for Outfalls 102,103,
110, 111, 113,114, 115, 116, 117, 121, 127, 128, 129, 130, 131, and 132 were eliminated from the draft
permit transmitted on September 21, 2016. The seeps will be covered under a Special Order by
Conocnt. Constructed seeps 104 and 106 will remain in the permit.
3. Added monitoring for lead and TDS for dewatering and decanting in rcoponoc to EPA - - - { Formatted: Normal, No bullets or numbering
comments.
4. The footnote under outfall 002 requiring physical/chemical treatment was modified to allow
the installation of tr atment if it is necessary.
5. A statement was added to condition A. (6) Effluent Limitations and Monitoring
Requirements for outfall 005 to require submittal of Form 2C Parts V and VI within 180 days of
commencement of operations.
6. Special conditions for inotream sampling and fish tio.,uc monitoring were modified to clarify
requirements (Sec A. (13) and A. (14)).
7. The mixing zone for outfall 002 was removed from the permit. Recent data chows that the
temperature standard is not exceeded at outfall 002. The Division does not consider that the mixing
zone in the current permit is justified since the conditions arc different from when the mixing zone
was established.
8. Added limits for 126 pollutants for outfall 005 since this outfall will discharge the cooling
tower-blowdown,
9. The groundwater monitoring well construction and sampling condition was eliminated
from the permit.
10. Special condition A. (30) Compliance Boundary was added to the permit.
11. The groundwater compliance boundary map was added to the permit.
Outfall 005 Temperature Mixing Zone:
Duke requested a mixing zone for temperature for Outfall 005. Outfall 005 is a proposed outfall that
will discharge among other flows, the cooling tower blowdown. A Cormix analysis was developed
to evaluate a mixing zone. Both summer and winter conditions were considered in the analysis. The
model was run under conservative a^.,umption such as the use of maximum design flow rate of 6
MGD for both summer and winter and a sensitivity analysis resulted in the use of the most
conservative river depth.
Summer Analysis The summer maximum effluent discharge temperature was estimated as 100°F.
Maximum ambient temperature was recorded as 86.3°F.
Winter Analysis The winter maximum effluent discharge temperature was estimated as 93.7°F.
The minimum ambient temperature was 35.5°F.
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The temperature water quality standard has two components: not to exceed 2.8 °C (5.04 °F) above
natural background and not to exceed 32 °C (89.6 °F). The critical condition modeled for the
summer was the maximum temperature. The critical condition modeled for the winter was the
temperature exceedance over background conditions.
The model includes the following ac.,umptions/ inputs:
gulf-all-005
Flow
6 MCD
Max summer temperature
Max winter temperature
Outfall structure
100 °F
93.7 °F
36" pipe followed by 10
feet wide rip rap channel
Summer 7Q10
287 cfc
Winter 7Q10
440 cfc
Summer max temperature
Winter min temperature
86,31F
35.5 °F
Summer AT
3.3 °F
Winter AT
58.2 °F
River width
200 ft (60.9 m)
River depth
Model results:
2.5 ft
Mi hig Zene
nt,tm . Taal (y)
Dilution
Summer
130 m (426.8 ft)
37 m (121.4 ft)
471
Winter
145 m (476 ft)
24.5 m (80.4 ft)
10.8
A mixing zone will be implemented comprising a distance of 145 meters downotr am of the outfall
and 37 meters wide. The mixing zone length is maximized for the winter condition and the width is,
maximized for the .,ummer condition. For both .,ummer and winter conditions the effluent i-
buoyant providing for passage of fish through the mixing zone. The mixing zone shall not result in
acute toxicity, prevent free passage of aquatic organisms, result in offensive conditions, produce
undesirable aquatic life or result in a dominance of nuisance species outside of the assigned mixing
zone; or endanger the public h alth or welfare.
Temperature monitoring will be implemented upstream and downstream at the edge of the mixing
zone to evaluate compliance with the temperature criteria outside of the mixing zone and to verify
the model predictions. If model predictions arc not validated the permit will be reopened to
implement more stringent requirements.
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The permit includes requirements to submit a mixing zone verification study and an assessment to
verify that the mixing zone does not prevent the pa --age of fish around the mixing zone. The
ac.,ec.,ment would include a biological component but is not intended to be a full BIP demonstration
due to the greatly reduced area of the hi.,toric thermal mixing zone. The .,tudy is intended to
confirm the projected impacts of the discharge that were presented in the CORMIX model.
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PROPOSED SCHEDULE FOR PERMIT ISSUANCE
Draft Permit to Public Notice: May 2, 2018
Permit Scheduled to I:rue: June 16, 2018
NPDES DIVISION CONTACT
If you have questions regarding any of the above information or on the attached permit, please
contact Teresa Rodriguez at [phone].
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Modifications included in the final permit:
1. The discharge from Outfall 106 was reclac.,ified as discharging to a UT to the Broad River.
The RPA was reviGed which re.,ulted in the implementation of limits for TDS and aluminum.
2. Sampling frequency for metals during dewatering was modified to weekly. Total bromide
monitoring was added to the monitoring requirements.
3. Sampling frequency for total arsenic, total mercury and total selenium during decanting was
modified to weekly. Total bromide monitoring was added to the monitoring requirements.
1. A footnote was added for the decanting and dewatering effluent pages that requires the
facility to discontinue the discharge if pollutant levels r ach 85 % of the allowable concentrations
and to report the event to the Division.
5. Footnote 8 for outfall 005 was modified to clarify that monthly monitoring is required
during normal operations and during decanting. In addition, the fecal coliform sample type was
changed to grab.
6. The downstr am sample location for the instr am monitoring required by special condition
A.(13) was modified to approximately 250 meters from the discharge.
7. Special condition A.(24) was modified to require the .,ubmittal of materials required by the
316(b) rule by 3.5 years from the i:ruancc of the permit and to add language stating that the
Division determined that operating and maintaining the existing Closed cycle recirculating system
meets the requirements for an interim BTA.
8. The Division evaluated the schedule of compliance for the FGD limits and determined that
Duke did not provide sufficient justification to delay the completion of the project until December
31, 2023. The compliance date was modified to December 31, 2021.
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