NC0003425_Fact Sheet_20170105 (3)

DEPARTEMENT OF ENVIRONMENTAL QUALITY
DIVISION OF WATER RESOURCES
FACT SHEET FOR NPDES PERMIT DEVELOPMENT
NPDES No. NC0003425
Facility Information
Applicant/Facility Name:
Duke Energy Progress/Roxboro Steam Electric Generating Plant
Applicant Address:
1700 Dunnaway Rd., Semora, NC 27343
Facility Address:
1700 Dunnaway Rd., Semora, NC 27343
Permitted Flow
Not limited
Type of Waste:
99.8 % Industrial, 0.2% - domestic
Facility/Permit Status:
Existing/Renewal
County:
Person
Miscellaneous
Receiving Stream:
Hyco Reservoir
Stream Classification:
WS-V, B
Subbasin:
03-02-05
303(d) Listed?:
No
Drainage Area (mi2):
Lake
Primary SIC Code:
4911
Summer 7Q10 (cfs)
0
Regional Office:
RRO
30Q2 (cfs):
0
Quad
Olive Hill
Average Flow (cfs):
0
Permit Writer:
Teresa Rodriguez
IWC (%):
100%
Date:
1/5/2017
Summary
The Roxboro Steam Electric Plant is an electric generating facility that uses steam turbine generation (via
four coal-fired units with a total net capacity of 2558 MW). Units No. 1 and 2 (385 MWe and 670 MWe,
respectively) use condensers as cooling devices. Units No. 3 and 4 (707MWe and 700 MWe, respectively)
use cooling towers as cooling devices.
The facility has three existing cooling water intake structures (CWISs). The source water for CWISs No.1
and 2 is the Hyco Reservoir. The source water for CWIS no. 4 is the site's cooling canal. The facility total
intake is approximately 1,114 MGD. The facility discharges to subbasin 030205 in the Roanoke River
Basin. Discharges are mostly industrial, with a very small domestic flow (internal Outfall 008) piped to
the on -site ash pond. Discharges from the ash pond (internal Outfall 002), once -through cooling water
and FGD treatment system (internal outfall 010) are discharged to the Discharge Canal (outfall 003). The
Discharge Canal and Coal Pile Runoff (outfall 006) both discharge to Hyco Reservoir. The Hyco
Reservoir is a 17.6 km2 waterbody constructed in 1963 by CP&L to serve as a cooling water source. The
receiving waterbody is class WS-V; B. The facility is located in the Lower Piedmont area of the state, the
applicable state water quality temperature standard is 32'C (89.6' F).
This facility is subject to EPA effluent guideline limits per 40 CFR 423 - Steam Electric Power Generating
Point Source Category which were amended November 3, 2015. The facility is also subject to the Cooling
Water Intake Structures Rules (40 CFR 125) effective October 14, 2014. The intake flow is > 125 MGD.
The facility operates five internal outfalls and two outfalls to Hyco Reservoir. Duke requested the
addition of three new outfalls on the permit; two to reflect the future treatment systems for the low
volume wastes as the ash basin will be closed and one for seeps and stormwater.
Description of existing outfalls:
• Outfall 003 - Heated Discharge Canal to Hyco Reservoir. The discharge canal combines all
internal outfalls (002, 005, 008, 009, 010) before discharging to Hyco Reservoir. In addition, once-

NPDES PERMIT FACT SHEET
Page 2
Roxboro Steam Electric Plant
NPDES No. NC00003425
through cooling water from condensers for units 1,2, and 3, once -through cooling water from
heat exchangers, seepage from ash pond, and stormwater runoff from plant drainage areas are
discharged to the discharge canal.
Outfall 006 - Coal Pile Runoff discharges directly to Hyco Reservoir. Coal pile runoff
wastewaters include runoff from the coal pile, limestone pile and gypsum pile, truck wheel wash
area and coal handling areas. Treatment is accomplished by neutralization, sedimentation and
equalization.
Internal Outfall 002 - Ash Pond discharging to the discharge canal. The ash pond receives
wastewater from the following source:
• Bottom ash transport waters
• Silo wash water
• Ash landfill leachate and runoff (this landfill receives CCR from Mayo and Roxboro
plants)
• Dry -ash handling system wash water
• Blowdown from Unit 4 cooling tower
• Coal mill rejects and pyrites
• Sewage treatment plant effluent
• Low volume waste consisting of boiler blowdown, equipment maintenance cleaning
wastewaters, RO reject wastewater and floor drains. Low volume wastes are treated by
neutralization.
• Emergency overflow from FGD system blowdown.
• Internal Outfall 005 - Cooling tower blowdown from Unit 4.
• Internal Outfall 008 - Treated domestic wastewater. The treatment system consists of a screen,
communitor, surge tank, aeration tank, clarifier, chlorine contact chamber and sludge holding
tank. A new package plant will be installed to replace the existing plant.
• Internal Outfall 009 - Chemical metal cleaning waste. Wastewaters from cleaning of the boilers is
generated every five to eight years. Every three to five years wastewaters are generated from
cleaning the heat exchangers. The wastewaters generated can be treated by evaporation or by
neutralization and precipitation.
• Internal Outfall 010 - Flue Gas Desulfurization (FGD) treatment system discharging to the
discharge canal. The scrubber system removes SOx by mixing flue gas with a limestone slurry.
The blowdown from the scrubber is discharged to a gypsum settling pond system then to a
bioreactor which utilizes microorganisms to reduce soluble contaminants to insoluble forms
(under anaerobic conditions) that then precipitate from solution. Wastewater is discharged to the
ash pond effluent channel. An emergency overflow from the FGD system blowdown discharges
to the ash pond.
Proposed Outfalls:
Outfall 001 (Seeps) - Stormwater and four seeps from the ash landfill flow to the intake canal
through a common outfall. This outfall was at one time permitted in a previous permit as outfall
001 and will be reinstated to monitor the seeps.
Internal Outfalls 012A and 012B - Low volume waste and other wastewaters. Duke will build two
basin treatment systems to treat wastewaters that now go to the ash basin.
2

NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant
Page 3 NPDES No. NC00003425
CWA 316 (W
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.
Temperature Mixing Zone - Outfall 003
The facility is located in the Lower Piedmont area of the state, the applicable state water quality
temperature standard is 32°C (89.6° F). The authorized temperature mixing zone for outfall 003 includes
the North Hyco Arm downstream of NC Hwy 57, the main body of Hyco Reservoir downstream of the
confluence of the Cobbs Creek Arm and the North Hyco Arm and the entire after bay lake. USGS data at
the after bay monitoring station (USGS Station 02077303) was reviewed for the period of January 2011 to
April 2016. Data shows that the temperature water quality standard was not exceeded for this period.
Maximum temperature recorded was 30.5°C.
Instream Monitoring
The permit requires monitoring of Hyco Reservoir in accordance to the Biological Monitoring Program as
approved by the Division. Based on the Divisions review of the reports the fish community is
comparable to other piedmont reservoirs and no problems were noted.
DATA REVIEW/PERMIT REOUIREMENTS
Internal Outfall 002 - Ash Pond
This outfall is subject to the Effluent Limitations Guidelines (ELG) in Table 1.
Table 1. ELG Outfall 002 (Prior to November 1, 2018)
Pollutant
Daily Maximum
Monthly Average
ELG
TSS
100 mg/1
30 mg/1
40 CFR 423.12 (b) (4)
Oil & Grease
20 mg/1
15 mg/1
40 CFR 423.12 (b) (4)
The current permit requires monitoring for flow and total selenium, limits for Oil & Grease and TSS. A
summary of DMR data for the period of January 2011 to January 2016 is included in Table 2. There have
been no violations of permit limits or conditions.
Table 2. DMR Summary Outfall 002
Parameter
Average 9r
Maximum
Minimum
Flow
10.8 MGD
48.3 MGD
3.1 MGD
TSS
5 mg/1
21 mg/1
< 2.5 mg/1
Total Selenium
14.6 µg/1
68.8 µg/1
< 10 µg/1
O&G
<5mg/1
13.5mg/1
<5mg/1
Table 3. Monitoring Requirements/Proposed Changes Outfall 002
Parameter
Monitoring requirements
Chan es
Basis
Flow
Monitor
No changes
15A NCAC 2B.0505
TSS
30 mg/1 monthly aver
100 mg/1 daily max
No changes
40 CFR 423.12(b)(4)
Oil & Grease
15 mg/1 monthly aver
20 mg/1 daily max
No Changes
40 CFR 423.12(b)(4)
Total Selenium
Monthly monitoring
No changes
Pollutant of concern
Turbidity, pH
No requirement
Monitor
Pollutant of concern for
dewatering/ decanting

NPDES PERMIT FACT SHEET
Page 4
Roxboro Steam Electric Plant
NPDES No. NC00003425
Schedule of Compliance Fly Ash/Bottom Ash:
As per 40 CFR 423.13 (k) (1) (i) bottom ash transport water shall not be discharged, compliance with this
section shall be as soon as possible beginning on November 1, 2018, but no later than December 31, 2023.
Duke utilizes wet bottom ash transport system. Duke is proposing to install a remote mechanical drag
chain system. Design of the system is expected to be completed in 8 months, followed by procurement in
12 months. Construction is expected to be completed in 13 months. Duke proposes a 16 month window
to optimize the system at full load and additional 6 months for potential permitting delays.
Consideration was given to the fact that Duke will be undertaking design, procurement and installation
activities in multiple facilities simultaneously. Duke will meet the no discharge of bottom ash
requirement by April 30, 2021.
Fly ash transport water is no longer discharged therefore Duke meets the compliance date of November
1, 2018.
Internal Outfall 002 - Dewatering
To meet the requirements of the Coal Ash Management Act of 2014, the facility needs to dewater two ash
ponds 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 2 MGD. The facility submitted data for the
standing surface water in the ash ponds, interstitial water in the ash, and interstitial ash water that was
treated by filters of various sizes. The following pollutants were detected at concentrations higher than
the water quality standards: selenium, arsenic and molybdenum. A new effluent and monitoring sheet is
included in the permit for the ash pond dewatering phase. As this is an internal outfall the water quality
standards are not applied. Monitoring will be required for selenium, arsenic, molybdenum, antimony
and copper.
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.
Outfall 003 - Discharge Canal (Combined outfallsj
DMR/Compliance Review
Data were reviewed for the period of January 2011 to March 2016. There have been no violations of
permit limits or conditions.
Table 4. DMR Summary Outfall 003
Parameter
Average
Maximum
Minimum
Flow (MGD)
840
1130
6.9
TRC
Not discharged
TP (mg/1)
< 0.036
< 0.05
< 0.05
TN (mg/1)
1 0.68
1.08
0.44
Temperature (°C)
29
41
13°C
Total Arsenic (µg/1)
6.2
17.1
< 2.8
pH (SU)
7.34
8
6.38
Toxicity Testing (003):
Current Requirement: Acute P/F at 90%, February, May, August, November.
Proposed Requirement: Acute P/F at 90%, February, May, August, November.
The facility passed 21 tests out of 21 tests performed for the period of January 2011 to January 2016.
rd

NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant
Page 5 NPDES No. NC00003425
Reasonable Potential Analysis Outfall 003:
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 003.
For the purposes of the RPA, the background concentrations for all parameters were assumed to be below
detection level. The RPA uses 95% probability level and 95% confidence basis in accordance with the EPA
Guidance entitled "Technical Support Document for Water Quality -based Toxics Control." With the
approval of the Triennial Review (2007-2014) of the NC Water Quality Standards by the Environmental
Management Commission (EMC) in 2014 and US -EPA (with some exceptions) on April 6, 2016, the
NPDES Permitting Unit is required to implement the new dissolved metal standards in all permits public
noticed after April 6, 2016. The RPA included evaluation of dissolved metals' standards, utilizing
measured hardness value of 100 mg/L CaCO3 for hardness -dependent metals.
A reasonable potential analysis was conducted for arsenic, copper, nickel, selenium, strontium, thallium,
chlorides and zinc. Arsenic data used for the RPA was collected between 2011 and 2016. Data for the
remaining parameters was from a special study for the period of March 2010 to August 2011. Based on
this analysis, the following permitting actions are proposed for this permit:
• Monitoring Only. The following parameters will receive a monitor -only requirement since they
did not demonstrate reasonable potential to exceed applicable water quality standards/criteria,
but the maximum predicted concentration was >50% of the allowable concentration: Arsenic,
selenium, chloride.
• No Limit or Monitoring: The following parameters will not receive a limit or monitoring, since
they did not demonstrate reasonable potential to exceed applicable water quality
standards/criteria and the maximum predicted concentration was <50% of the allowable
concentration: copper, nickel, strontium, and zinc.
• Limit: The following parameter will receive a limit since it demonstrated reasonable potential to
exceed the applicable water quality standards/criteria: thallium.
Mercury Evaluation Outfall 003:
A mercury evaluation was conducted in accordance with the permitting guidance developed for the
implementation of the statewide Mercury TMDL to determine the need for a limit and Mercury
Minimization Plan (MMP). Monitoring for mercury is not required for outfall 003 but mercury data was
collected during a special study during the period of March 2010 to August 2011. The water quality based
effluent limitation (WQBEL) for mercury is 12 ng/l. The technology based effluent limit (TBEL) is 47
ng/l. None of the annual averages exceeds the WQBEL or TBEL, no limit is required. See the attached
mercury evaluation spreadsheet.
Table 5. Mercury Evaluation
2010
2011
# of Samples
20
16
Annual Average, ng/L
3.6
4.4
Maximum Value, ng/L
7.63
6.92
TBEL, n /L
47
WQBEL, ng/L
12.0

NPDES PERMIT FACT SHEET
Page 6
Table 6. Monitoring Requirements/Proposed Changes Outfall 003
Roxboro Steam Electric Plant
NPDES No. NC00003425
Parameter
Monitoring
Changes
Basis
requirements/Limits
Flow
Monitor
No changes
15A NCAC 2B.0505
TRC
200 µg/l
Modified limit to 28 µg
State WQ standards, 15A NCAC
instantaneous max
/1 daily max
2B .0200. The water quality
standard is more stringent than
the effluent guidelines limit.
TP
Monitor
No changes
15A NCAC 2B .0500
TN
Monitor
No changes
15A NCAC 2B .0500
Temperature
Monitor
No changes
Approved Mixing zone
Total Arsenic
Monitor
No changes
Based on results from RPA,
Predicted concentration greater
than 50% of allowable.
Total Selenium
No requirement
Quarterly monitoring
Based on results from RPA,
Predicted concentration greater
than 50% of allowable.
Total Thallium
No requirement
0.24 µg/l Daily max
Based on results from RPA.
limit
0.24 µg/l Monthly Max
Chloride
No requirement
Quarterly monitoring
Based on results from RPA,
Predicted concentration greater
than 50% of allowable.
pH
6 to 9 SU
No changes
State WQ standards, 15A NCAC
2B .0200
Acute toxicity
P/F 90%
No changes
State WQ standards, 15A NCAC
2B .0200
Internal Outfall 005 - Cooling Tower Blowdown from Unit 4
This outfall is subject to the ELGs in Table 7.
Table 7. ELG Outfall 005
Pollutant
Dail Maximum I Monthl Avera e
pH
6 to 9 SU
40 CFR 423.12 (b) (1)
Free Available
Chlorine
0.5 mg/l
0.2 mg/l
40 CFR 423.12 (d) (1)
126 Pollutants
No detectable amounts
40 CFR 423.13 (d) (1)
Total Chromium
0.2 mg/l
0.2 mg/l
40 CFR 423.13 (d) (1)
Total Zinc
1.0 mg/l
1.0 mg/l
40 CFR 423.13 (d) (1)
The permit includes monitoring for flow and Total Residual Chlorine (TRC), limits for Free Available
Chlorine, Total Chromium, Total Zinc and 126 priority pollutants.
Special condition A. (14) in the permit doesn't allow the discharge of the cooling tower blowdown to the
discharge canal, it has to be discharged to the ash pond. With the modifications planned to the site and
the future closure of the existing ash pond Duke will like to have the option to discharge the blowdown
to the discharge canal. This will continue to be an internal outfall subject to the same limits under 40 CFR
423. The limits apply before it comingles with any other waste stream so there is no change in limits or
other permit conditions by allowing the cooling tower blowdown to discharge into the discharge canal.
J

NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant
Page 7 NPDES No. NC00003425
DMR/Compliance Review:
Data were reviewed for the period of January 2011 to January 2016. There have been no violations of
permit limits or conditions. Flow was the only parameter monitored at this outfall since the facility did
not chlorinate or added chromium or zinc for maintenance activities. Flow is reported as 7.2 MGD on a
daily basis.
Table 8. Monitoring Requirements/Proposed Changes Outfall 005
Parameter
Monitoring
Requirements/Limits
Changes
Basis
Flow
Monitor
No changes
15A NCAC 2B.0505
Free available
500 µg/l daily max
No changes
40 CFR 423.13 (d)(1)
chlorine
200 µg/l monthly average
Total Residual
Chlorine
Monitoring
No changes
40 CFR 423.13 (d) (2)
Total chromium
200 µg/l daily max
No changes
40 CFR 423.13 (d)(1)
200 µg/l monthly average
Total Zinc
1.0 mg/l daily max
No changes
40 CFR 423.13 (d)(1)
1.0 mg/l monthly average
The 126 priority
pollutants
No detectable amount
No changes
40 CFR 423.13 (d)(1)
Outfall 006 - Coal Pile Runoff
This outfall is subject to the ELG in Table 9.
Table 9. ELG Outfall 006
Pollutant
Daily Maximum
Monthly Average
ELG
TSS
50 mg/l
40 CFR 423.12 (b) (9)
pH
6 to 9 SU
40 CFR 423.12 (b) (1)
DMR/Compliance Review:
Data were reviewed for the period of January 2008 to March 2013. There have been no violations of
permit limits or conditions.
Table 10. DMR Summary Outfall 006
Parameter
Average
Maximum
Minimum
Flow (MGD)
0.23
0.05
0.002
TSS (Mg/ 1)
2.6
76.6
< 2.5
H (SU)
7.39
8.9
6.04
Priority Pollutant Scan:
The application included the results of one scan. Selenium was detected above the water quality
standard.
7

NPDES PERMIT FACT SHEET
Page 8
Table 11. Monitoring Requirements/Proposed Changes Outfall 006
Roxboro Steam Electric Plant
NPDES No. NC00003425
Parameter
Monitoring
Changes
Basis
requirements/Limits
Flow
Monitor
No changes
15A NCAC 213.05
TSS
50 mg/1 instantaneous
Added Monthly average
40 CFR 423.12(b)(9),
max
limit of 30 mg/1
40 CFR 122.45
pH
6 to 9 SU
No changes
40 CFR 423.12 (b) (1)
Total selenium
No requirement
5.0 µg/1 Monthly Average
RPA
56 µg/1 Daily Max
Acute toxicity
P/F 90%
No changes g
State WQ standards,15A
NCAC 213.0200
Internal Outfall 008 - Domestic WWTP
Table 12. DMR Review Outfall 008
Parameter
Average
Maximum
Minimum
Flow (MGD)
0.007
0.01
0.002
TSS (mg/1)
14.7
30
5
pH (SU)
6.8
7.3
6.5
BOD (mg/1)
10.4
28
2.1
NH3N (mg/1)
0.8
1.6
< 0.1
Table 13. Monito ing Requirements/ Proosed Changes Outfall 008
Parameter
Monitoring I
requirements/Limits
Changes
Basis
Flow
0.015 MGD
Add effluent page
WWTP will be upgraded during
for 0.025 MGD
this permit cycle
TSS
30 mg/1 monthly
No changes
NPDES rules for secondary
aver
treatment of domestic
45 mg/1 daily max
wastewater,15A 213.0400
pH
6 to 9 SU
No changes
State WQ standards,15A 213
.0200
BOD
30 mg/1 monthly
No changes
NPDES rules for secondary
aver
treatment of domestic
45 mg/1 daily max
wastewater,15A 213.0400
Total ammonia
Monitor
No changes
DWQ Policy
Internal Outfall 009 - Chemical cleaning waste
Table 14. Monitoring Requirements/Proposed Changes Outfall 009
Parameter
Monitoring
re uirements/Limits
Changes
Basis
Flow
Monitor
No changes
15A NCAC 2B.0505
Total Copper
1.0 mg/1 monthly aver
No changes
40 CFR 423.13 (e)
1.0 mg/1 daily max
Total Iron
1.0 mg/1 monthly aver
No changes
40 CFR 423.13 (e)
1.0 mg/1 daily max
TSS
30 mg/1 monthly aver
No changes
40 CFR 423.13 (e)
100 mg/1 daily max
Oil & Grease
15 mg/1 monthly aver
No changes
40 CFR 423.13 (e)
20 mg/1 daily max
N.

NPDES PERMIT FACT SHEET
Page 9
Roxboro Steam Electric Plant
NPDES No. NC00003425
Internal Outfall 010 - FGD
This outfall is subject to the Effluent Limitations Guidelines (ELG) in Table 15. These are new limitations
promulgated November 3, 2015.
Table 15. ELG Outfall 010
Pollutant
Daily Maximum K I Monthly Average
ELG
pH
6 to 9 SU
40 CFR 423.12 (b) (1)
TSS
100 mg/1
30 mg/1
40 CFR 423.12 (b) (11)
Oil and grease
20 mg/1
15 mg/1
40 CFR 423.12 (b) (11)
Total Arsenic
11 µg/1
8 µg/1
40 CFR 423.13 (g) (1) (i)
Total Mercury
788 n /1
356 n /1
40 CFR 423.13 () (1) (i)
Total Selenium
23 µ /1
12 µ /1
40 CFR 423.13 (g) (1) (i)
Nitrate/nitrite
17 mg/1
4.4 mg/1
40 CFR 423.13 (g) (1) (i)
The current permit includes monitoring for flow, total beryllium, total mercury, total antimony, total
selenium, total silver and total vanadium. Table 16 includes a summary of DMR data for the period of
January 2011 to January 2016. There have been no violations of permit limits or conditions.
Table 16. DMR Summary Outfall 010
Parameter
Average
Maximum
Minimum
Flow (MGD)
0.84
1.77
0.01
Total Beryllium (µg/1)
3.9
10
< 1
Total Mercury (µg/1)
1.08
9.6
< 1
Total Selenium (µg/1)
102
712
< 50
Total Silver (µg/1)
6
8.4
< 5
Total Antimony (µ /1)
31
70
< 25
Total Vanadium (µg/1)
< 25
< 25
< 5
Table 17. Monitoring Requirements/Proposed Changes Outfall 010
Parameter
Monitoring I
requirements/Limits
Changes
Basis
Flow
Monitor
N o changes
7Remove
15A NCAC 2B.0505
Total Beryllium
Monitor
monitoring
Internal outfall, not a
parameter of concern.
Total Vanadium
Monitor
Remove monitoring
Internal outfall, not a
parameter of concern.
Total Antimony
Monitor
Remove monitoring
Internal outfall, not a
parameter of concern.
Total Silver
Monitor
Remove monitoring
Internal outfall, not a
parameter of concern.
Total Arsenic
No monitoring
11 µg/1 daily max and
8 µg/1 monthly average
40 CFR 423.13 (g) (1) (i)
Total Selenium
Monitor
23 µg/1 daily max and
12 µg/1 monthly
40 CFR 423.13 (g) (1) (i)
average
Nitrate/Nitrite
No monitoring
17 mg/1 daily max and
4.4 mg/1 monthly
40 CFR 423.13 (g) (1) (i)
average
Total Mercury
Monitoring
788 ng/1 daily max and
356 ng/1 monthly
40 CFR 423.13 (g) (1) (i)
average.
b

NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant
Page 10 NPDES No. NC00003425
Schedule of Compliance FGD:
40 CFR 423 establishes compliance dates for the new limitations. Permittee must meet limits as soon as
possible beginning on November 1, 2018 but no later than December 31, 2023.
Duke utilizes a biological treatment system to treat FGD wastewaters. Duke anticipates that it will be
required to install physical/chemical treatment followed by selenium reduction technology to meet the
FGD guidelines. Evaluation of new technologies and design of the system is expected to take 30 months.
The evaluation phase includes evaluation of existing treatment system, flow optimization, siting of the
new system within the plant, selection of technology and permitting. Procurement is expected to be
completed in 20 months, construction and tie-in expected to be completed in 16 months considering that
tie-in has to be done during outages. Startup and optimization under all expected operating conditions is
estimated for 15 months. An additional 6 months is included in the schedule for potential permitting
delays. Duke will meet the FGD ELG by December 31, 2023. As the new treatment system will be placed
in operation and the old pond may still discharge until it is decommissioned. A new outfall is included in
the permit for the new system.
Provosed Outfalls:
Seeps:
The facility identified 16 unpermitted seeps. The following seeps from the ash landfill discharge through
a common outfall to Hyco Reservoir at the intake canal: S-09, S-10, S-11, and S-12. The outfall used to be
the authorized outfall for the effluent from the old ash basin. The seep flow into a concrete culvert and
channel that leads to the intake canal. An effluent channel determination was conducted by the Raleigh
Regional Office staff on December 15, 2016.
Seeps S-01, S-02, S-03, S-04, S-05, S-06, S-07, S-08, S-14, S-18, and S-19 are internal to outfall 003. Seeps 1
through 7 are chimney drains from the ash basin dam. The flow from the combined seeps account for less
than 0.0005 % of the total discharge. These are considered de -minimum discharges and will be included
in the authorized wastewaters discharging through outfall 003.
Outfall 001
Four seeps discharge to the intake canal at Hyco Reservoir where former Outfall 001 used to discharged.
The Division will reinstate outfall 001 to monitor the discharge from the seeps and stormwater. The
following seeps discharge through outfall 001: S-09, S-10, S-11, and S-12.
RPA
A RPA was conducted for proposed outfall 001. RPA was conducted for total arsenic, cadmium,
chlorides, total chromium, total copper, total lead, total mercury, total molybdenum, total nickel,
selenium, total zinc, antimony, sulfate and total thallium. As a result of the RPA limits are required for
the following parameters: fluoride, arsenic, sulfate and selenium.
Mercury
Mercury data was collected for the seeps during 2014 and 2015. 2014 data was collected using method 245
which has a higher detection limit that 1631. Data for 2015 was used to evaluate a need for a limit. The
annual average was 5.2 ng/l, no limit will be implemented.
In addition to the limits described above all the seep 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 lead, total nickel, and total selenium, and limits as described in Table
18.
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NPDES PERMIT FACT SHEET
Page 11
Table 18. Outfall 001 Proposed Limits/Monitoring:
Roxboro Steam Electric Plant
NPDES No. NC00003425
Parameter
Monitoring requirements/Limits
Basis
Flow
Monitor
15A NCAC 2B.0505
pH
6 to 9 SU
State WQ standards, 15A 2B .0200
Total copper, total antimony,
Monitor
Coal ash parameters of concern.
total lead, total zinc, total
barium, total iron, total
manganese, total nickel, total
mercury, chlorides
Fluoride
Limit -1.8 mg/l
RPA
Total Arsenic
Limit -10 µg/l
RPA
Total Selenium
Limits 5 µg/l Monthly Average
RPA
56 µg/l Daily Max
Sulfates
Limit - 250 mg/l (Monthly average
RPA
& daily max)
TDS, Hardness, Conductivity
Monitor
Parameters of concern
Acute toxicity
Quarterly Limit
State WQ standards, 15A NCAC
2B .0200
Low volume Waste Treatment Systems:
Two new treatment systems will be installed to treat wastewaters currently delivered to the ash basin.
Low volume wastes, metal cleaning wastes, stormwater, and other miscellaneous wastes that are routed
to the ash basin will be rerouted to new treatment systems. Duke proposes two separate treatment
systems. The new outfalls will be designated as outfall 012A and outfall 012B. The overflow from the
012B basin will be designated as outfall 012C. Duke estimated that design, construction and start up of
the new treatment system will be completed within 30 months of permit issuance.
Internal Outfall 012A - treatment system for the landfill leachate, silo wash water, contact and non -
contact storm water and discharging to the discharge canal.
Table 19. Outfall 012A Proposed Limits/Monitoring:
Parameter
Monitoring
Basis
ff requirements/Limits
Flow
Monitor
15A NCAC 2B.0505
Total Suspended Solids
30 mg/l Monthly Average
40 CFR 423.12 (b)(3)
100 mg/l Daily Max
Oil & Grease
15 mg/l Monthly Average
40 CFR 423.12 (b)(3)
20 mg/l Daily max
Internal Outfall 012B - treatment system for plant low volume wastes, FGD treatment system effluent,
domestic waste treatment system, anhydrous ammonia emergency discharge, metal cleaning wastes,
stormwater runoff, and cooling tower blowdown. The discharge from outfall 012B will go to the
discharge canal.
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NPDES PERMIT FACT SHEET
Page 12
Table 20. Outfall 012B Proposed Limits/Monitoring:
Roxboro Steam Electric Plant
NPDES No. NC00003425
Parameter
Monitoring requirements/Limits
Basis
Flow
Monitor
15A NCAC 2B.0505
Total Suspended Solids
30 mg/1 Monthly Average
100 mg/1 Daily Max
40 CFR 423.12 (b)(3)
Oil & Grease
15 mg/1 Monthly Average
20 mg/1 Daily max
40 CFR 423.12 (b)(3)
Ammonia
Monitor
Monitor during emergency discharge
of anh drous ammonia
Emergency Outfall 012C - The basin discharging through 012B will have an emergency overflow
Table 21. Outfall 012C Proposed Limits/Monitoring:
Parameter
Monitoring
requirements/Limits
Basis
Flow
Monitor
15A NCAC 2B.0505
Total Suspended Solids
30 mg/1 Monthly Average
100 mg/1 Daily Max
40 CFR 423.12 (b)(3)
Oil & Grease
15 mg/1 Monthly Average
20 mg/1 Daily max
40 CFR 423.12 (b)(3)
Ammonia
Monitor
Monitor during emergency
discharge of anhydrous ammonia
Arsenic
Monitor
Parameter of concern
Mercury
Monitor
Parameter of concern
Selenium
Monitor
Parameter of concern
Nitrate/ nitrite
Monitor
Parameter of concern
Copper
Monitor
Parameter of concern
Iron
Monitor
Parameter of concern
Public Notice/Public Hearing
The first draft of this permit was public noticed on August 30, 2016. A public hearing was held on
October 4, 2016. A second public notice is being published since the first notice went to a newspaper out
of the area.
Summary of permit modifications:
• A separate effluent page for the dewatering of the ash ponds (Outfall 002) was added to the
permit.
• Outfall 001 was reinstated to monitor discharge of seeps and stormwater.
• A new internal outfall (Outfall 011) was added to the permit to monitor the discharge from the
proposed FGD treatment system.
• Special Condition A. (14) that prohibited the discharge of cooling tower blowdown from outfall
005 to the discharge canal was eliminated from the permit.
• A special condition was added to describe Section 316(b) requirements for submittal of applicable
information.
• A special condition was added to the permit to require an Ash Pond Closure Plan.
• A Special Condition was added to the permit to require compliance with Senate Bill 729 (Coal
Ash Management Act).
• Attachment 1 entitled "Groundwater Monitoring Plan' was added to the permit.
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NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant
Page 13 NPDES No. NC00003425
• Attachment 2 entitled "Plan for Identification of New Discharges' was added to the permit.
Summary of modifications to the first draft permit:
• Condition A. (1) Effluent Limitations and Monitoring Requirements for seeps - monitoring
requirements were updated to include the same list of parameters monitored for seeps in other
Duke permits.
• Condition A. (2) Effluent Limitations and Monitoring Requirements for the ash basin -
monitoring was added for arsenic, molybdenum, and chromium. In addition, a statement was
added with the requirement to use physical/chemical treatment during dewatering.
• Condition A. (2) & A. (3) Effluent Limitations and Monitoring Requirements for the ash basin -
Statement regarding no discharge of fly ash was modified to read that no discharge of fly ash is
allowed. The statement pertaining to the schedule of compliance with the ELG for zero
discharge of bottom ash was corrected to read April 30, 2021 instead of November 1, 2018.
• Condition A. (10) & A. (11) Effluent Limitations and Monitoring Requirements for the FGD -
footnote 3 was corrected to read December 31, 2023.
• Turbidity sampling was eliminated from internal outfall 002. Turbidity monitoring is included
at outfall 003.
• Supplement to cover sheet was modified to include flows that were not listed and add
proposed outfalls and outfalls.
• Condition A. (6) Effluent Limitations and Monitoring Requirements outfall 006:
o Oil and Grease limits were added since it receives truck wash waters.
o The RPA was revised and limits for total selenium were added.
• Condition A. (4) Effluent Limitations and Monitoring Requirements for outfall 003:
o Footnote 4 was modified to include a statement regarding the addition of temperature
limits if the facility is not in compliance with the temperature water quality standard.
o Reporting of the temperature at the afterbay station was added to the monitoring
requirements for outfall 003, reporting of temperature at 4C, 4D was eliminated.
o The RPA was revised and limits for thallium were added.
• Condition A. (17)- temperature reporting requirements were modified.
• A. (8) Effluent Limitations and Monitoring Requirements for outfall 008 - monitoring
requirements were modified to require quarterly monitoring for one year after the new plant
start operations, annual monitoring is required after one year of quarterly monitoring.
• Two new internal outfalls (Outfall 012A and 012B) were added to the permit for the two
proposed retention basins for the treatment of low volume wastes that are now sent to the ash
basin. Duke will build two separate wastewater treatment systems to handle the wastes that go
to the ash pond. These ponds will be in different locations in the site and will require each a
separate outfall into the effluent channel.
• Outfall 012C was added to the permit for the emergency overflow of the proposed lined
retention basin discharging through outfall 012B.
• A table including a list of all the seeps locations was added to Condition A. (14).
Public Notice schedule:
Draft permit to Public Notice: January 22, 2017
Permit Scheduled to issue: March 10, 2017
STATE CONTACT
If you have any questions on any of the above information or on the attached permit, please contact
Teresa Rodriguez at [phone].
NAME: DA
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NPDES PERMIT FACT SHEET
Page 14
Amendment to Fact Sheet - March 2017
Roxboro Steam Electric Plant
NPDES No. NC00003425
Comments were received from Duke Energy, Sierra Club and the Southern Environmental Law Center
Duke Energy Comments:
1. Include extracted groundwater as contributing flow to 003 and 001. - The groundwater flow was
not included because it is not an existing source and it has not been characterized. The
groundwater treatment system is not in operation and is not expected to commence for
approximately three years. When the groundwater system is defined and a schedule for
operation is known the permit can be modified.
2. List retention basis (012) as potential flow path for cooling tower blowdown (Outfall 005) - the
retention basin (012B) is listed as potential flow path for outfall 005
3. List retention basin as potential flow path for domestic wastewater (Outfall 008) - the retention
basin (012B) is listed as potential flow path for outfall 008.
4. List retention basin for potential flow path for landfill leachate - its listed on 12 A, does it goes to
12A or 1213?
5. Modify WET sampling frequency from monthly to quarterly for outfall 001- the sampling
frequency will not be modified, all the outfall for seeps receive monthly sampling for WET.
6. Footnote for outfall 001 related to fly ash discharges should read "no fly ash should be
discharged after November 1, 2018 - the footnote was corrected.
7. Remove pH limitations from internal outfalls 002 - the pH limit was removed
8. Clarify that flow limit of 2.0 MGD only applies for interstitial water treated through
physical/chemical treatment -
9. Add language on special condition A.(5) to include that the cooling water can be discharged
through the retention basin or the discharge canal - the flow path is already included in the
supplement to cover sheet, it will not be included in the outfall description in condition A.(5).
10. Remove monthly average limit for selenium in outfall 006, this outfall is not continuous and is
associated with precipitation events only - ?
11. Add the following language to Condition A.(15): "All previously identified seeps from this
facility are contributing flows to outfalls 003 and 001. There are no seeps that discharge directly to
jurisdictional waters". List all the seeps that are tributary to outfall 003 -
12. Clarify language in condition A.(19) that temperature readings from the afterbay will be obtained
from the existing USGS Gaging station and that a malfunction of the station will not be
considered a violation of the permit - proposed language: "Temperature readings from the
afterbay shall be obtained from the existing USGS station (02077303). In case where the permittee
experiences equipment problems and is unable to obtain daily temperatures from the monitoring
station temperature monitoring must be reestablished within five working days."
Comments received from public:
SELC:
14