NC0085359_Permit (Issuance)_20141121

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bENR
North Carolina Department of Environment and Natural Resources
Pat McCrory
Governor
November 21, 2014
Mr. Ed Goscicki, Public Works Director
Union County Public Works
500 North Main Street, Suite 500
Monroe, NC 28112-4730
Subject: Issuance of NPDES Permit NC0085359
Renewal & Expansion
Twelve Mile Creek WWTP
Union County
Facility Class IV
Dear Mr. Ed Goscicki:
John E. Skvarla, III
Secretary
Division personnel have reviewed and approved your application for expansion and renewal of the subject
permit. Accordingly, we are forwarding the attached NPDES discharge permit. This permit is issued
pursuant to the requirements of North Carolina General Statute 143-215.1 and the Memorandum of
Agreement between North Carolina and the U.S. Environmental Protection Agency dated October 15, 2007
(or as subsequently amended).
Please note that the receiving stream is listed as an impaired waterbody on the North Carolina 2014 303(d)
Impaired Waters List for Fish Community (Fair Rating). Addressing impaired waters is a high priority with
the Division, and instream data will continue to be evaluated. If there is noncompliance with permitted
effluent limits and stream impairment can be attributed to your facility, then mitigative measures may be
required.
The following items are in response to the comment letter received from Union County on
October 30, 2014.
• The monitoring frequency for BOD5, TSS, and fecal coliform was listed incorrectly in the draft
permit. In accordance with DWR's Guidelines for Exceptionally Performing Facilities it was
changed to "twice per week." The Guidelines do not provide for a twice per month allowance as
requested by the County.
• Instream sampling for DO and temperature remain in the permit. Continued instream sampling
will help to confirm the modeling predictions determined based upon the WWTP's flow
expansions.
• As requested, an Effluent Limitation and Monitoring Requirements sheet was added for a
permitted flow of 7.5 MGD. See section A. (2).
• The Standard Conditions from November 2011 have been attached to this permit.
• The modifications to the WER calculations have been received and will be evaluated separately
'from the processing of the permit modification and renewal. The Division will provide
comments on the modified WER calculations after other Division Branches have a chance to
review it.
1617 Mail Service Center, Raleigh, North Carolina 27699-1617
Phone: [phone] Internet: www.ncwaterquality.org
An Equal Opportunity \ Affirmative Action Employer — Made in part by recycled paper

Mr. Ed Goscicki, Public Works Director
November 21, 2014
Page 2 of 3
• The concept of the bubble permit for Total Phosphorus between different Permittees has been
pursued in other watersheds within North Carolina. To discuss how this process has been
implemented in other basins, the County should contact Mike Templeton in the NPDES
Permitting Unit at 919-807-6402.
As identified previously, the renewal permit contains the -following significant changes from
your current permit:
• The requirement to begin reporting discharge monitoring data electronically within 270 days of the
NPDES Permit effective date using the NC DWR's Electronic Discharge Monitoring Report (eDMR)
internet application has been added to your final NPDES permit. [See Footnote #1 under Sections A.(1),
A.(2), A.(3), and A.(4) and Special Condition A.(8.)]
For information on eDMR, registering for eDMR and obtaining an eDMR user account, please visit the
following web page: http://portal.ncdenr.org/web/wq/admin/bog/ipu/edmr.
For information on EPA's proposed NPDES Electronic Reporting Rule, please visit the following web
site: http://www2.epa.gov/compliance/proposed-npdes-electronic-reporting-rule.
• Copper and zinc limits in the previous permits were based on demonstrated reasonable potential to
exceed water quality standards in South Carolina. The applicable site -specific copper/zinc standards
were originally developed based on a study by Union County in conjunction with the State of South
Carolina, and based on Water Effect Ratio (WER) calculations. Based on the Reasonable Potential
Analysis for this permit renewal, no reasonable potential was shown for copper and zinc to violate SC
WQS's. In addition, the maximum predicted effluent concentrations for copper and zinc, determined by
the Reasonable Potential Analysis, were both less than fifty percent of their site -specific standards
(permit limitations). In accordance with NC NPDES monitoring guidance, copper and zinc monitoring
was removed from the permit.
• Some of the wording has changed in Special Condition A. (5.), Chronic Toxicity Monitoring, please
review each paragraph carefully.
• Special Condition A. (7.) has been modified to include the specific three years in which the Effluent
Pollutant Scans shall be performed (2016, 2017, and 2018). In addition, at the end of the Special
Condition, 2nd species Toxicity Testing Requirements for municipal permit renewals per Federal
Regulations [40 CFR 122.21(j)(5)] have been added.
• In accordance with the 2012 Statewide Mercury TMDL mercury effluent data was reviewed. All the
annual averages were less than the Water Quality Based Effluent Limit and the Technology Based
Effluent Limit. The County shall continue to monitor mercury as part of its Effluent Pollutant Scans and
perform a Mercury Minimization Plan (MMP) as described in Special Condition A.(9.). Please note that
the MMP shall be developed within 180 days of the NPDES Permit effective date. A sample MMP was
developed through a stakeholder review process and has been placed on the Division website for
guidance at: http://portal.ncdenr.org/web/wq/swp/ps/npdes
• Instream data confirms that the WWTP effluent is not the cause of the high fecal coliform values in that
segment of the receiving stream. In fact the WWTP effluent appears to dilute the fecal coliform levels
immediately downstream of the WWTP outfall. In accordance with DWR guidance dated 4/22/2002, if
the receiving stream is not impaired for fecal coliform and it is not a Class B waterbody, instream
monitoring for fecal coliform can be removed. Fecal coliform monitoring was removed from the permit's
instream sampling requirements for all three stations.
• NPDES guidance dated 4/22/2002 recommends that conductivity be removed from instream sampling
requirements for 100% domestic wastewater permits. Union County's Twelve Mile Creek WWTP does
not have a pretreatment program and receives no industrial wastewaters. Monitoring for conductivity was
removed from the effluent and instream sampling requirements.
• The Total Phosphorus mass loading limits (Monthly Average = 41.71bs/day, Annual Average = 20.85
lbs/day) were capped to ensure no additional TP load, even with expansion to 12.0 MGD. These limits

Mr. Ed Goscicki, Public Works Director
November 21, 2014
Page 3 of 3
were based on a Union County /DWQ/SCDHEC Settlement Agreement for the inclusion of phosphorus
limits to dischargers to the main stem of the Catawba (upstream of Lake Wateree), to comply with the
SC lake standard of 0.06 mg/1. At 12 MGD, the TP mass limits equate to a Monthly Average
concentration of 0.42 mg/1, and an Annual Average concentration of 0.21 mg/1.
• In accordance with DWR guidance for "Exceptionally Performing Facilities" a review of effluent
sampling data from 7/1/2011 through 6/30/2014 confirmed that sampling frequency reductions for
BOD5, TSS, and fecal coliform should be granted. Monitoring for BOD5, TSS, and fecal coliform was
reduced from daily to twice per week in the permit renewal. Ammonia -nitrogen effluent sampling
results did not meet the Guidance requirements to allow for a sampling reduction.
• Upon each expansion, the County shall revert back to daily sampling for BOD5, TSS, and Fecal coliform.
After 6 months of daily sampling, the County can return to twice per week sampling for the parameters
for which no permit limit violation has occurred. See footnote #8 under Sections A.(2, 3, and 4).
If any parts, measurement frequencies or sampling requirements contained in this permit are unacceptable
to you, you have the right to an adjudicatory hearing upon written request within thirty (30) days following
receipt of this letter. This request must be in the form of a written petition, conforming to Chapter 150B of
the North Carolina General Statutes, and filed with the Office of Administrative Hearings (6714 Mail
Service Center, Raleigh, North Carolina 27699-6714). Unless such demand is made, this decision shall be
final and binding.
Please note that this permit is not transferable except after notice to the Division. The Division may
require modification or revocation and reissuance of the permit. This permit does not affect the legal
requirements to obtain other permits which may be required by the Division of Water Resources or any
other Federal, State, or Local governmental permits that may be required.
If you have any questions concerning this permit, please contact Julie Grzyb by email
([e-mail]) or phone at [phone].
Sincerely,
Thomas A. Reeder, Director
Division of Water Resources, NCDENR
Enclosure: NPDES Permit NC0085359
cc: NPDES Unit
Central Files
Mooresville Regional Office / Surface Water Protection Section
e-copy:
EPA Region 4
Susan Meadows, Aquatic Toxicity Branch
Jim Struve, P.E., Hazen and Sawyer
Michael Montebello, Manager Domestic Wastewater Permitting Section, SC DHEC
Wayne Harden, SC DHEC

Permit NC0085359
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER RESOURCES
NPDES PERMIT
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
In compliance with the provision of North Carolina General Statute 143-215.1, other lawful
standards and regulations promulgated and adopted by the North Carolina Environmental
Management Commission, and the Federal Water Pollution Control Act, as amended, the
Union County Public Works Department
is hereby authorized to discharge wastewater from a facility located at the
Twelve Mile Creek Wastewater Treatment Plant
8299 Kensington Drive
Waxhaw, NC
Union County
to receiving waters designated as Twelve Mile Creek in the Catawba River Basin in
accordance with effluent limitations, monitoring requirements, and other conditions set forth in
Parts I, II, III, and IV hereof.
This permit shall become effective January 1, 2015.
This permit and authorization to discharge shall expire at midnight on December 31, 2019.
Signed this day November 21, 2014:
Thomas A. Reeder, Director
Division of Water Resources
By Authority of the Environmental Management Commission
Page 1 of 17

Permit NC0085359
SUPPLEMENT TO PERMIT COVER SHEET
All previous NPDES Permits issued to this facility, whether for operation or discharge are
hereby revoked, and as of this issuance, any previously issued permit bearing this number is no
longer effective. Therefore, the exclusive authority to operate and discharge from this facility
arises under the permit conditions, requirements, terms, and provisions included herein.
The Union County Public Works Department is hereby authorized to:
1. Continue to operate an existing 6.0 MGD wastewater treatment facility that includes the following
components:
• Influent pump station with stand-by generator
• Self-cleaning influent filter screening structure and manual bar screen
• Vortex grit chamber
• Four FAO basins (anoxic and oxidation reactors)
• FAO distribution structure
• MLSS distribution structure
• Four final clarifiers
• Four tertiary sand filters
• Two ultraviolet light disinfection systems
• Cascade post aeration
• Sludge thickening facility with a gravity belt thickener and associated polymer storage
and feed system
• Four aerobic digesters with diffused aeration
• Sodium aluminate storage and feed facilities for phosphorus removal
• Odor control facilities
• Main stand-by power generator
This facility is located at the Twelve Mile Creek Wastewater Treatment Plant off Kensington
Drive near Waxhaw in Union County.
2. Upon issuance of an Authorization to Construct (ATC) permit by the Division and submission of
the Engineer's Certification for construction completion, operate a wastewater treatment facility
up to a design flow of 7.5 MGD, and
3. Upon issuance of an Authorization to Construct (ATC) permit by the Division and submission of
the Engineer's Certification for construction completion, operate a wastewater treatment facility
up to a design flow of 9 MGD, and
4. Upon issuance of an Authorization to Construct (ATC) permit by the Division and submission of
the Engineer's Certification for construction completion, operate a wastewater treatment facility
up to a design flow of 12 MGD, and
5. Discharge from said treatment works at the location specified on the attached map into Twelve
Mile Creek, a class C stream in the Catawba River Basin.
Page 2 of 17

Permit NC0085359
PART I
A. (1) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS — 6 MGD
During the period beginning upon the effective date of this permit and lasting until expansion above 6 MGD or
expiration, the Permittee is authorized to discharge from outfall 001. Such discharge shall be limited and
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EFFLUENT
CHARACTERISTICS
LIMITS
MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily (
Max.
Measurement
Frequency
Sample
Type
Sample
Location2
Flow
6.0 MGD
Continuous
Recording
I or E
BOD, 5-day, 20°C
(March -October) 3
5.0 mg/L
7.5 mg/L
Twice per Week
Composite
I & E
BOD, 5-day, 20°C
(November — February) 3
10.0 mg/L
15.0 mg/L
Twice per Week
Composite
I & E
Total Suspended Solids 3
30.0 mg/L
45.0 mg/L
Twice per Week
Composite
I & E
NH3 as N
(March — October)
1.0 mg/L
3.0 mg/L
Daily
Composite
E
NH3 as N
(November - February)
2.0 mg/L
6.0 mg/L
Daily
Composite
E
Dissolved Oxygen, mg/L4
Daily
Grab
E
Dissolved Oxygen, mg/L
(June through September)
3/Week
Grab
U & D
Dissolved Oxygen, mg/L
(October through May)
1/Week
Grab
U & D
pH
> 6.0 and < 9.0 standard units
Daily
Grab
E
Total Nitrogen, mg/L
(NO2+NO3+TKN)
Monthly
Composite
E
Total Phosphorus 5
Monthly Average: 41.70 lbs/day
12 Month Avg.: 20.85 lbs/day
Monthly
Composite
E
Temperature, °C
Daily
Grab
E
Temperature, °C
(June through September)
3/Week
Grab
U & D
Temperature, °C
(October through May)
1/Week
Grab
U & D
Fecal Coliform (geo. mean)
200/100 ml
400/100 ml
Twice per Week
Grab
E
Chronic Toxicity6
Quarterly
Composite
E
Effluent Pollutant Scan7
(Parameter code: NC01)
Monitor and Report
Footnote 7
Footnote 7
E
Footnotes on following page
Page 3of17

Permit NC0085359
A. (1) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
[continued]
Footnotes to previous table:
1. No later than 270 days from the effective date of this permit, begin submitting discharge monitoring
reports electronically using NC DWR's eDMR application system. See Special Condition A (8).
2. E=Effluent; I=Influent; U=Upstream; D=Downstream. Upstream: 50 feet upstream from the outfall.
Downstream samples shall be collected at each of two locations, D1 and D2. D1: One quarter mile
downstream from the outfall, before confluence with the first tributary. D2: at NCSR 1301.
Additional downstream dissolved oxygen monitoring is recommended to provide DO stream profile
of Twelve Mile Creek in North Carolina and South Carolina.
3. The monthly average effluent BOD5 and Total Suspended Solids concentrations shall not exceed
15% of the respective influent value (85% removal).
4. The daily average dissolved oxygen effluent concentration shall not be less than 6.0 mg/L.
5. Special condition A (6) describes the methodology for calculation of the monthly average and 12-
month limits.
6. Chronic Toxicity (Ceriodaphnia) P/F @ 90% with testing in February, May, August and November,
refer to A (5).
7. The permittee shall perform three Effluent Pollutant Scans during the term of this permit.
See Special Condition A (7).
There shall be no discharge of floating solids or foam.
Page 4 of 17

Permit NC0085359
A. (2) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS — 7.5 MGD
During the period beginning upon expansion above 6 MGD and lasting until expiration or expansion above 7.5
MGD, the Permittee is authorized to discharge from outfall 001. Such discharge shall be limited and monitored.'
EFFLUENT
CHARACTERISTICS
LIMITS
MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily
Max.
Measurement
Frequency
Sample
Type
Sample
Location2
Flow
7.5 MGD
Continuous
Recording
I or E
BOD, 5-day, 20°C
(March- October) 3
5.0 mg/L
7.5 mg/L
Twice per Week8
Composite
I & E
BOD, 5-day, 20°C
(November — February) 3
10.0 mg/L
15.0 mg/L
Twice per Week8
Composite
I & E
Total Suspended Solids 3
30.0 mg/L
45.0 mg/L
Twice per Week8
Composite
I & E
NH3 as N
(March - October)
1.0 mg/L
3.0 mg/L
Daily
Composite
E
NH3 as N
(November — February)
1.9 mg/L
5.7 mg/L
Daily
Composite
E
Dissolved Oxygen, mg/L4
Daily
Grab
E
Dissolved Oxygen, mg/L
(June through September)
3/Week
Grab
U & D
Dissolved Oxygen, mg/L
(October through May)
1/Week
Grab
U & D
pH
> 6.0 and < 9.0 standard units
Daily
Grab
E
Total Nitrogen, mg/L
(NO2+NO3+TKN)
Monthly
Composite
E
Total Phosphorus 5
Monthly Average: 41.70 Ibs/day
12 Month Avg.: 20.85 Ibs/day
Monthly
Composite
E
Temperature, °C
Daily
Grab
E
Temperature, °C
(June through September)
3/Week
Grab
U & D
Temperature, °C
(October through May)
1/Week
Grab
U & D
Fecal Coliform (geo. mean)
200/100 ml
400/100 ml
Twice per Week8
Grab
E
Chronic Toxicity6
Quarterly
Composite
E
Effluent Pollutant Scan7
(Parameter code: NC01)
Monitor and Report
Footnote 7
Footnote 7
E
Footnotes on following page
Page 5 of 17

Permit NC0085359
A. (2) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
[continued]
Footnotes to previous table:
1. No later than 270 days from the effective date of this permit, begin submitting discharge monitoring
reports electronically using NC DWR's eDMR application system. See Special Condition A (8).
2. E=Effluent; I=Influent; U=Upstream; D=Downstream. Upstream: 50 feet upstream from the outfall.
Downstream samples shall be collected at each of two locations, D1 and D2. D1: One quarter mile
downstream from the outfall, before confluence with the first tributary. D2: at NCSR 1301.
Additional downstream dissolved oxygen monitoring is recommended to provide DO stream profile
of Twelve Mile Creek in North Carolina and South Carolina.
3. The monthly average effluent BOD5 and Total Suspended Solids concentrations shall not exceed
15% of the respective influent value (85% removal).
4. The daily average dissolved oxygen effluent concentration shall not be less than 6.0 mg/L.
5. Special condition A (6) describes the methodology for calculation of the TP monthly average and
12-month limits. At full permitted flow of 12 MGD, TP mass limits equate to 0.42 mg/I (Monthly Avg)
and 0.21 mg/I (Annual Avg).
6. Chronic Toxicity (Ceriodaphnia) P/F @ 90% with testing in February, May, August and November,
refer to A (5).
7. The permittee shall perform three Effluent Pollutant Scans during the term of this permit.
See Special Condition A (7).
8. Upon expansion above 6 MGD, the County shall revert back to daily sampling of these parameters.
After 6 months of daily sampling, the Permittee may return to twice per week sampling for the
parameters for which no permit limit violation has occurred.
There shall be no discharge of floating solids or foam.
Page 6 of 17

Permit NC0085359
A. (3) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS — 9 MGD
During the period beginning upon expansion above 7.5 MGD and lasting until expiration or expansion above 9
MGD, the Permittee is authorized to discharge from outfall 001. Such discharge shall be limited and monitored
by the Permittee as specified below:
EFFLUENT
CHARACTERISTICS
Flow
BOD, 5-day, 20°C
October) 3
(March-
BOD, 5-day, 20°C
(November — February) 3
Total Suspended Solids 3
NH3 as N
(March - October)
NH3 as N
(November — February)
Dissolved Oxygen, mg/L4
Dissolved Oxygen, mg/L
through September)
(June
Dissolved Oxygen, mg/L
through May)
(October
pH
Total Nitrogen, mg/L
(NO2+NO3+TKN)
Total Phosphorus 5
Temperature, °C
Temperature, °C
(June through September)
Temperature, °C
through May)
(October
Fecal Coliform (geo. mean)
Chronic Toxicity6
Effluent Pollutant Scan7
(Parameter code: NC01)
Monthly
Average
9.0 MGD
5.0 mg/L
LIMITS
Weekly
Average
Daily
Max.
MONITORING REQUIREMENTS
Measurement
Frequency
Sample
Type
Sample
Location2
7.5 mg/L
Continuous
Twice per WeekB
Recording
Composite
I or E
I&E
10.0 mg/L
30.0 mg/L
1.0 mg/L
15.0 mg/L
Twice per WeekB
Composite
I&E
45.0 mg/L
3.0 mg/L
Twice per WeekB
Daily
Composite
Composite
I&E
1.9 mg/L
5.7 mg/L
Daily
Composite
Daily
Grab
3/Week
Grab
U &D
1/Week
Grab
> 6.0 and < 9.0 standard units
Daily
Monthly
Grab
U &D
Composite
Monthly Average: 41.70 lbs/day
12 Month Avg.: 20.85 lbs/day
Monthly
Daily
Composite
Grab
3/Week
Grab
U &D
1/Week
Grab
U &D
200/100 ml
400/100 ml
Twice per WeekB
Quarterly
Grab
Composite
Monitor and Report
Footnote 7
Footnote 7
Footnotes on following page
Page 7 of 17

Permit NC0085359
A. (3) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
[continued]
Footnotes to previous table:
1. No later than 270 days from the effective date of this permit, begin submitting discharge monitoring
reports electronically using NC DWR's eDMR application system. See Special Condition A (8).
2. E=Effluent; I=Influent; U=Upstream; D=Downstream. Upstream: 50 feet upstream from the outfall.
Downstream samples shall be collected at each of two locations, D1 and D2. D1: One quarter mile
downstream from the outfall, before confluence with the first tributary. D2: at NCSR 1301.
Additional downstream dissolved oxygen monitoring is recommended to provide DO stream profile
of Twelve Mile Creek in North Carolina and South Carolina.
3. The monthly average effluent BOD5 and Total Suspended Solids concentrations shall not exceed
15% of the respective influent value (85% removal).
4. The daily average dissolved oxygen effluent concentration shall not be less than 6.0 mg/L.
5. Special condition A (6) describes the methodology for calculation of the TP monthly average and
12-month limits. At full permitted flow of 12 MGD, TP mass limits equate to 0.42 mg/I (Monthly Avg)
and 0.21 mg/I (Annual Avg).
6. Chronic Toxicity (Ceriodaphnia) P/F @ 90% with testing in February, May, August and November,
refer to A (5).
7. The permittee shall perform three Effluent Pollutant Scans during the term of this permit.
See Special Condition A (7).
8. Upon expansion above 7.5 MGD, the County shall revert back to daily sampling of these
parameters. After 6 months of daily sampling, the Permittee may return to twice per week sampling
for the parameters for which no permit limit violation has occurred.
There shall be no discharge of floating solids or foam.
Page 8 of 17

Permit NC0085359
A. (4) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS —12 MGD
During the period beginning upon expansion above 9 MGD and lasting until expiration, the Permittee is
authorized to discharge from outfall 001. Such discharge shall be limited and monitored by the Permittee as
specified below:
EFFLUENT
CHARACTERISTICS
Monthly
Average
Flow
BOD, 5-day, 20°C
(March - October) 3
BOD, 5-day, 20°C
(November - February) 3
Total Suspended Solids3
NH3 as N
(March — October 31)
NH3 as N
(November — February)
Dissolved Oxygen, mg/L4
Dissolved Oxygen, mg/L
(June through September)
Dissolved Oxygen, mg/L
(October through May)
pH
Total Nitrogen, mg/L
(NO2+NO3+TKN)
Total Phosphorus
Temperature, °C
12.0 MGD
Weekly
Average
5.0 mg/L 7.5 mg/L
10.0 mg/L 15.0 mg/L
30.0 mg/L 45.0 mg/L
Daily
Max.
Measurement
Frequency
Sample
Type
Sample
Location2
Continuous Recording I or E
Twice per Week8 Composite I & E
Twice per Week8 Composite I & E
Twice per Week8 Composite I & E
1.0 mg/L 3.0 mg/L Daily
1.9 mg/L 5.7 mg/L Daily
Daily
3/Week
1/Week
> 6.0 and < 9.0 standard units Daily
Composite E
Composite E
Grab E
Grab U & D
Grab U & D
Grab E
Monthly Composite E
Temperature, °C
(June through September)
Temperature, °C
_October throu�,;h May)
Fecal Coliform (geo. mean)
Monthly Average: 41.70 lbs/day
12 Month Avg.: 20.85 Ibs/day
200/100 ml
400/100 ml
Chronic Toxicity6
Effluent Pollutant Scan7
(Parameter code: NC01)
Footnotes on following page
Monitor and Report
Monthly Composite E
Daily
3/Week
1/Week
Twice per Week8
Grab
Grab
Grab
Grab
E
U&D
U&D
Quarterly Composite E
Footnote 7 Footnote 7 E
Page 9 of 17

Permit NC0085359
A. (4) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
[continued]
Footnotes to previous table:
1. No later than 270 days from the effective date of this permit, begin submitting discharge monitoring
reports electronically using NC DWR's eDMR application system. See Special Condition A (8).
2. E=Effluent; I=Influent; U=Upstream; D=Downstream. Upstream: 50 feet upstream from the outfall.
Downstream samples shall be collected at each of two locations, D1 and D2. D1: One quarter mile
downstream from the outfall, before confluence with the first tributary. D2: at NCSR 1301.
Additional downstream dissolved oxygen monitoring is recommended to provide DO stream profile
of Twelve Mile Creek in North Carolina and South Carolina.
3. The monthly average effluent BOD5 and Total Suspended Solids concentrations shall not exceed
15% of the respective influent value (85% removal).
4. The daily average dissolved oxygen effluent concentration shall not be less than 6.0 mg/L.
5. Special condition A (6) describes the methodology for calculation of the TP monthly average and
12-month limits. At full permitted flow of 12 MGD, TP mass limits equate to 0.42 mg/I (Monthly Avg)
and 0.21 mg/I (Annual Avg).
6. Chronic Toxicity (Ceriodaphnia) P/F @ 90% with testing in February, May, August and November,
refer to A (5).
7. The permittee shall perform three Effluent Pollutant Scans during the term of this permit.
See Special Condition A (7).
8. Upon expansion above 9 MGD, the County shall revert back to daily sampling of these parameters.
After 6 months of daily sampling, the Permittee may return to twice per week sampling for the
parameters for which no permit limit violation has occurred.
There shall be no discharge of floating solids or foam.
Page 10 of 17

Permit NC0085359
A. (5) CHRONIC TOXICITY PASS/FAIL PERMIT LIMIT — FOR 6.0, 7.5, 9.0, AND 12.0 MGD
The effluent discharge shall at no time exhibit observable inhibition of reproduction or significant mortality to
Ceriodaphnia dubia at an effluent concentration of 90 %.
The permit holder shall perform at a minimum, quarterlv monitoring using test procedures outlined in the "North
Carolina Ceriodaphnia Chronic Effluent Bioassay Procedure," Revised December 2010, or subsequent versions
or "North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure" (Revised- December 2010) or
subsequent versions. The tests will be performed during the months of February, May, August, and November.
These months signify the first month of each three-month toxicity testing quarter assigned to the facility. Effluent
sampling for this testing must be obtained during representative effluent discharge and shall be performed at the
NPDES permitted final effluent discharge below all treatment processes.
If the test procedure performed as the first test of any single quarter results in a failure or ChV below the
permit limit, then multiple -concentration testing shall be performed at a minimum, in each of the two
following months as described in "North Carolina Phase II Chronic Whole Effluent Toxicity Test
Procedure" (Revised -December 2010) or subsequent versions.
The chronic value for multiple concentration tests will be determined using the geometric mean of the highest
concentration having no detectable impairment of reproduction or survival and the lowest concentration that does
have a detectable impairment of reproduction or survival. The definition of "detectable impairment," collection
methods, exposure regimes, and further statistical methods are specified in the "North Carolina Phase II Chronic
Whole Effluent Toxicity Test Procedure" (Revised -February 1998) or subsequent versions.
All toxicity testing results required as part of this permit condition will be entered on the Effluent Discharge
Monitoring Form (MR-1) for the months in which tests were performed, using the parameter code TGP3B for the
pass/fail results and THP3B for the Chronic Value. Additionally, DWR Form AT-3 (original) is to be sent to the
following address:
Attention: North Carolina Division of Water Resources
Water Sciences Section/Aquatic Toxicology Branch
1621 Mail Service Center
Raleigh, North Carolina 27699-1621
Completed Aquatic Toxicity Test Forms shall be filed with the Water Sciences Section no later than 30 days after
the end of the reporting period for which the report is made.
Test data shall be complete, accurate, include all supporting chemical/physical measurements and all
concentration/response data, and be certified by laboratory supervisor and ORC or approved designate signature.
Total residual chlorine of the effluent toxicity sample must be measured and reported if chlorine is employed for
disinfection of the waste stream.
Should they?. be no discharge of flow from the facility during a month in which toxicity monitoring is required, the
permittee will complete the information located at the top of the aquatic toxicity (AT) test form indicating the facility
name, permit number, pipe number, county, and the month/year of the report with the notation of "No Flow" in the
comment area of the form. The report shall be submitted to the Water Sciences Section at the address cited
above.
Should the permittee fail to monitor during a month in which toxicity monitoring is required, monitoring will be
required during the following month. Assessment of toxicity compliance is based on the toxicity testing quarter,
which is the three month time interval that begins on the first day of the month in which toxicity testing is required
by this permit and continues until the final day of the third month.
Should any test data from this monitoring requirement or tests performed by the North Carolina Division of Water
Resources indicate potential impacts to the receiving stream, this permit may be re -opened and modified to
include alternate monitoring requirements or limits.
NOTE: Failure to achieve test conditions as specified in the cited document, such as minimum control organism
survival, minimum control organism reproduction, and appropriate environmental controls, shall constitute an
invalid test and will require immediate follow-up testing to be completed no later than the last day of the month
following the month of the initial monitoring.
Page 11 of 17

Permit NC0085359
A. (6) TOTAL PHOSPHORUS (TP) MONITORING
The Permittee shall calculate a 12-month rolling average mass loading as the sum of monthly loadings, according
to the following equations:
(1) Monthly Average (pounds/day) = TP x Qw x 8.34
Where:
TP = the arithmetic average of total phosphorus concentrations (mg/L) obtained via composite samples
(either daily, weekly, or monthly average values) collected during the month
Qw = the average daily waste flow (MGD) for the month
8.34= conversion factor, from (mg/L x MGD) to pounds
The 12-month rolling average mass loading is defined as the sum of the monthly average loadings for the
previous 12 months inclusive of the reporting month:
12
(2) 12-Month Average Mass Loading (pounds/day)=
TPina =12 (inclusive of reporting month)
Where:
TPma is defined as the total phosphorus monthly average mass loading (calculated above).
The monthly average and 12-month average mass loadings shall be reported on the attached worksheet [see
next page] and submitted with the Discharge Monitoring Report (DMR) for Twelve Mile Creek WWTP.
The Permittee shall report the TP concentration for each sample on the appropriate DMR. Reporting of and
compliance with the TP limit shall be done on a monthly basis.
Page 12 of 17

Permit NC0085359
Reporting Month:
Beginning Month:
Ending Month:
Union County
Twelve Mile Creek WWTP
Nutrient Worksheet
NPDES Permit NC0085359
(Month 1)
(Month 12)
Monthly Average Total Phosphorus
pounds/day
Month 1
Month 2
Month 3
Month 4
Month 5
Month 6
Month 7
Month 8
Month 9
Month 10
Month 11
Month 12
12-Month Mass Average
Loading
Note: The TP mass loadings for the current reporting month should be entered for Month 1.
Page 13 of 17

Permit NC0085359
A. (7) EFFLUENT POLLUTANT SCAN
The Permittee shall perform a total of three (3) Effluent Pollutant Scans for all parameters listed below. One scan
must be performed in each of the following years: 2016, 2017, and 2018. Analytical methods shall be in accordance
with 40 CFR Part 136 and shall be sufficiently sensitive to determine whether parameters are present in
concentrations greater than applicable standards and criteria. Samples should be collected with one quarterly
toxicity test each year, and must represent seasonal variation [i.e., do not sample in the same quarter every year].
Unless otherwise indicated, metals shall be analyzed as "total recoverable."
Ammonia (as N)
Chlorine (total residual, TRC)
Dissolved oxygen
Nitrate/Nitrite
Kjeldahl nitrogen
Oil and grease
Phosphorus
Total dissolved solids
Hardness
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Copper
Lead
Mercury (EPA Method 1631E)
Nickel
Selenium
Silver
Thallium
Zinc
Cyanide
Total phenolic compounds
Volatile organic compounds:
Acrolein
Acrylonitrile
Benzene
Bromoform
Carbon tetrachloride
Chlorobenzene
Chlorodibromomethane
Chloroethane
2-chloroethylvinyl ether
Chloroform
Dichlorobromomethane
1,1-dichloroethane
1,2-dichloroethane
Trans-1,2-dichloroethylene
1,1-dichloroethylene
1,2-dichloropropane
1,3-dichloropropylene
Ethylbenzene
Methyl bromide
Methyl chloride
Methylene chloride
1,1,2,2-tetrachloroethane
Tetrachloroethylene
Toluene
1,1,1-trichloroethane
1,1,2-trichloroethane
Trichloroethylene
Vinyl chloride
Acid -extractable compounds:
P-chloro-m-cresol
2-chlorophenol
2,4-dichlorophenol
2,4-dimethylphenol
4, 6-d i n itro-o-c reso l
2,4-dinitrophenol
2-nitrophenol
4-nitrophenol
Pentachlorophenol
Phenol
2,4,6-trichlorophenol
Base -neutral compounds:
Acenaphthene
Acenaphthylene
Anthracene
Benzidine
Benzo(a)anthracene
Benzo(a)pyrene
3,4 benzofluoranthene
Benzo(ghi)perylene
Benzo(k)fluoranthene
Bis (2-chloroethoxy) methane
Bis (2-chloroethyl) ether
Bis (2-chloroisopropyl) ether
Bis (2-ethylhexyl) phthalate
4-bromophenyl phenyl ether
Butyl benzyl phthalate
2-chloronaphthalene
4-chlorophenyl phenyl ether
Chrysene
Di-n-butyl phthalate
Di-n-octyl phthalate
Dibenzo(a,h)anthracene
1,2-dichlorobenzene
1,3-dichlorobenzene
1,4-dichlorobenzene
3,3-dichlorobenzidine
Diethyl phthalate
Dimethyl phthalate
2,4-dinitrotoluene
2,6-dinitrotoluene
1,2-diphenylhydrazine
Fluoranthene
Fluorene
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocyclo-pentadiene
Hexachloroethane
Indeno(1,2,3-cd)pyrene
Isophorone
Naphthalene
Nitrobenzene
N-nitrosodi-n-propylamine
N-nitrosodimethylamine
N-nitrosodiphenylamine
Phenanthrene
Pyrene
1,2,4-trichlorobenzene
Reporting. Test results shall be reported on DWQ Form -A MR-PPA1 (or in a form approved by the Director) by
December 31st of each designated sampling year. The report shall be submitted to the following address: NC
DENR / DWR / Central Files, 1617 Mail Service Center, Raleigh, North Carolina 27699-1617.
Page 14 of 17

Permit NC0085359
Additional Toxicity Testing Requirements for Municipal Permit Renewal. Please note that Municipal facilities
that are subject to the Effluent Pollutant Scan requirements listed above are also subject to additional toxicity
testing requirements specified in Federal Regulation 40 CFR 122.21(j)(5). The US EPA requires four (4) toxicity
tests for a test organism other than the test species currently required in this permit. The multiple species tests
should be conducted either quarterly for a 12-month period prior to submittal of the permit renewal application, or
four tests performed at least annually in the four and one half year period prior to the application. These tests
shall be performed for acute or chronic toxicity, whichever is specified in this permit. The multiple species toxicity
test results shall be filed with the Aquatic Toxicology Branch at the following address:
North Carolina Division of Water Resources
Water Sciences Section/Aquatic Toxicology Branch
1621 Mail Service Center
Raleigh, North Carolina 27699-1621
Contact the Division's Aquatic Toxicology Branch at 919-743-8401 for guidance on conducting the additional
toxicity tests and reporting requirements. Results should also be summarized in Part E (Toxicity Testing Data) of
EPA Municipal Application Form 2A, when submitting the permit renewal application to the NPDES Permitting
Unit.
Page 15 of 17

Permit NC0085359
A. (8) ELECTRONIC REPORTING OF DISCHARGE MONITORING REPORTS
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 in late 2013.
NOTE: This special condition supplements or supersedes the following sections within Part II of this permit
(Standard Conditions for NPDES Permits):
• Section B. (11.) Signatory Requirements
• Section D. (2.) Reporting
• Section D. (6.) Records Retention
• Section E. (5.) Monitoring Reports
1. Reporting [Supersedes Section D. (2.) and Section E. (5.) (a)1
Beginning no later than 270 days from the effective date of this permit, the permittee shall begin reporting
discharge monitoring data electronically using the NC DWR's Electronic Discharge Monitoring Report (eDMR)
internet application.
Monitoring results obtained during the previous month(s) shall be summarized for each month and submitted
electronically using eDMR. The eDMR system allows permitted facilities to enter monitoring data and submit
DMRs electronically using the internet. Until such time that the state's eDMR application is compliant with
EPA's Cross -Media Electronic Reporting Regulation (CROMERR), permittees will be required to submit all
discharge monitoring data to the state electronically using eDMR and will be required to complete the eDMR
submission by printing, signing, and submitting one signed original and a copy of the computer printed eDMR
to the following address:
NC DENR / DWR / Information Processing Unit
ATTENTION: Central Files / eDMR
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
If a permittee is unable to use the eDMR system due to a demonstrated hardship or due to the facility being
physically located in an area where less than 10 percent of the households have broadband access, then a
temporary waiver from the NPDES electronic reporting requirements may be granted and discharge
monitoring data may be submitted on paper DMR forms (MR 1, 1.1, 2, 3) or alternative forms approved by the
Director. Duplicate signed copies shall be submitted to the mailing address above.
Requests for temporary waivers from the NPDES electronic reporting requirements must be submitted in
writing to the Division for written approval at least sixty (60) days prior to the date the facility would be
required under this permit to begin using eDMR. Temporary waivers shall be valid for twelve (12) months and
shall thereupon expire. At such time, DMRs shall be submitted electronically to the Division unless the
permittee re -applies for and is granted a new temporary waiver by the Division.
Information on eDMR and application for a temporary waiver from the NPDES electronic reporting
requirements is found on the following web page:
http://portal. ncdenr.orq/web/wq/admin/boq/ipu/edmr
Regardless of the submission method, the first DMR is due on the last day of the month following the
issuance of the permit or in the case of a new facility, on the last day of the month following the
commencement of discharge.
Page 16 of 17

Permit NC0085359
2. Signatory Requirements [Supplements Section B. (11.) (b) and supersedes Section B. (11.) (d)l
All eDMRs submitted to the permit issuing authority shall be signed by a person described in Part II, Section
B. (11.)(a) or by a duly authorized representative of that person as described in Part II, Section B. (11.)(b). A
person, and not a position, must be delegated signatory authority for eDMR reporting purposes.
For eDMR submissions, the person signing and submitting the DMR must obtain an eDMR user account and
login credentials to access the eDMR system. For more information on North Carolina's eDMR system,
registering for eDMR and obtaining an eDMR user account, please visit the following web page:
http://portal. ncdenr.orq/web/wq/admin/bog/ipu/edmr
Certification. Any person submitting an electronic DMR using the state's eDMR system shall make the
following certification [40 CFR 122.22]. NO OTHER STATEMENTS OF CERTIFICATION WILL BE
ACCEPTED:
"I certify, under penalty of law, that this document and all attachments were prepared under my direction or
supervision in accordance with a system designed to assure that qualified personnel properly gather and
evaluate the information submitted. Based on my inquiry of the person or persons who manage the system, or
those persons directly responsible for gathering the information, the information submitted is, to the best of
my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for
submitting false information, including the possibility of fines and imprisonment for knowing violations."
3. Records Retention [Supplements Section D. (6.)1
The permittee shall retain records of all Discharge Monitoring Reports, including eDMR submissions. These
records or copies shall be maintained for a period of at least 3 years from the date of the report. This period
may be extended by request of the Director at any time [40 CFR 122.41].
A. (9) Mercury Minimization Plan (MMP)
The permittee shall develop and implement a mercury minimization plan during this permit term. The MMP shall
be developed within 180 days of the NPDES Permit Effective Date, and shall be available for inspection on -site.
A sample MMP was developed through a stakeholder review process and has been placed on the Division
website for guidance (http://portal.ncdenr.org/web/wq/swp/ps/npdes, under Model Mercury Minimization Plan).
The MMP should place emphasis on identification of mercury contributors and goals for reduction. Results shall
be summarized and submitted with the next permit renewal.
Page 17 of 17

Facility Information
Latitude: 34°57'01" Sub -Basin: 03-08-38
Longitude: 80°45'44" 8-Digit HUC 03050103
Quad #: H15NE
Stream Class: C
Receiving Stream: Twelve Mile Creek NOT TO SCALE
Permitted Flow: 6.0 and 12.0 MGD
Twelve Mile Creek WWTP
NC0085359
Union County