NC0025453_Final_Permit_Major_Mod_TN_Credits_20200915

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
LINDA CULPEPPER
Director
NORTH CAROLINA
Environmental Quality
September 15, 2020
James Warren, WWTP Operations Supt.
Town of Clayton
P.O. Box 879
Clayton, North Carolina 27520
Subject: Issuance of NPDES Permit Modification
Permit NCO025453
Little Creek WRF
Johnston County
Grade IV Biological WPCS
SIC Code 4952
Dear Mr. Warren:
In accordance with Town of Clayton s request to include newly purchased nutrient offset
credits in its NPDES permit, and having received documentation of that purchase, the Division
of Water Resources is forwarding herewith the revised permit for the Little Creek Water
Reclamation Facility. 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).
The Division published notice of the draft permit on July 23, 2020, in The News and Observer
inviting public comment on the proposed modification. We received no response from the
general public. The Division's Public Water Supply Section provided its concurrence the permit,
as is necessary for discharges to Water Supply waters. And Restoration Systems/ FR Flat
Swamp and our Nutrient Offset and Riparian Buffer Mitigation Banking Program suggested
certain changes and clarification.
RS Flat Swamp, LLC has, by its September 4, 2020 Nutrient Offset Credit Transfer Certificate,
documented that the Town has purchased and paid in full for 715,858.18 lbs (23,861.941bs/yr
for 30 years) of Nitrogen Offset Credits available from the RS Flat Swamp Mitigation Bank. The
Division accepts this as sufficient for the issuance of the subject permit modification.
The Division is issuing the permit modification as originally proposed except for two minor
changes:
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 11617 Mail Service Center I Raleigh, North Carolina 27699-1617
919.707.9000

Issuance of NPDES Permit Modification
Permit NCO025453
September 15, 2020
• The September 4 purchase date for the offset credits has been added to the table of
allocations and offset credits in Condition A.(6.) of the permit; and
Footnote 3 below that same table has been split into two footnotes. Footnote 3 still
describes the offset credits purchase but, consistent with our Mitigation Banking
Program, no longer refers to "estuary' credits. The new Footnote 4 describes the
application of the credits in the Towri s permit, including transport considerations and
application of the uncertainty ratio from the Neuse rule,15A NCAC 02B .0713 (formerly
.0234). The allocations and credits listed in the table have not been changed.
Although the Transfer Certificate and the permit describe the credits as having a 30-year term, it
is our intent to convert them to permanent credits as allowed in the revised Neuse wastewater
rule,15A NCAC 02B .0713 (formerly 02B .0234). We will work with you to effect that change.
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 any other Federal, State, or Local governmental permit
that may be required. If you have any questions concerning the permit, please contact Mike
Templeton at [phone] or at mike.templeton@ncdenr. ov.
Sincerely,
� 1
T�w S. Daniel Smith
Director
Enclosure: Final Permit and Fact Sheet, NCO025453
Copies (with encl.): NPDES Files
eCopies (with encl.): NPDES Permitting Section, EPA Region IV
Scott Vinson, DWR Raleigh Regional Office, Surface Water Protection
DWR Basin Planning Branch
Mark Vander Borgh, DWR Water Sciences Section

Permit NCO025453
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENTAL QUALITY
DIVISION OF WATER RESOURCES
PFR MIT
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
In compliance with the provisions 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
Town of Clayton
is hereby authorized to discharge wastewater from a facility located at the
Little Creek Water Reclamation Facility
1000 Durham Street Extension
Clayton
Johnston County
to receiving waters designated as the Neuse River in the Neuse River Basin
in accordance with the effluent limitations, monitoring requirements, and other applicable conditions
set forth in Parts I, II, III, and IV hereof.
This permit shall become effective.............................................................................................October 1, 2020.
This permit and authorization to discharge shall expire at midnight on ............................. March 31, 2024.
Signed this day ...............September 15, 2020.
S. Daniel Smith, Director
Division of Water Resources
By Authority of the Environmental Management Commission

Permit NCO025453
SUPPLEMENT TO PERMIT COVER SHEET
All previous NPDES Permits issued to this facility, whether for operation or discharge are hereby revoked. As of
this permit 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 Town of Clayton
is hereby authorized to:
1. Continue to operate and maintain an existing 2.5 MGD wastewater treatment facility consisting of
the following components:
• mechanical screening and grit removal system,
• influent pump station
• 214,500 gallon anaerobic basin,
• 300,000 gallon anoxic tank,
• oxidation basin No. 2,
• 200,000 gallon anoxic tank
• oxidation basin No. 1,
• three (3) secondary clarifiers,
• two tertiary filters,
• ultraviolet disinfection with back-up chlorination/ dechlorination,
• 90,000 gallon aerated digester/ sludge stabilization tank,
• 360,000 gallon sludge holding tank,
• sludge loading station,
• sludge thickening building with rotary drum thickener
• non -potable water system using reclaimed treated wastewater
• reclaimed water pump station
This facility is located at the Little Creek Water Reclamation Facility, Durham Street Extension,
Clayton, Johnston County, and
2. Discharge from said treatment works at the location specified on the attached map via Outfall 001
into the Neuse River, classified WS-IV, NSW, CA waters in the Neuse River Basin.
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Permit NCO025453
PART
A.(1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [2.5 MGD]
[15A NCAC 02B .0400 et seq.,15A NCACO2B .0500 et seq.] Grade IV
Biological Water Pollution Control System [15A NCAC 08G .0302]
(a.) During the period beginning on the effective date of the permit and lasting until expiration, the
permittee is authorized to discharge treated municipal and industrial wastewater from Outfall
001. Such discharges shall be limited and monitored' by the permittee as specified below:
PARAMETER
Parameter Code
EFFLUENT LIMITS
MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type
Sample
Locationz
Flow 50050
2.5 MGD
Continuous
Recording
I or E
Total Monthly Flow (MG) 82220
Monitor and Report
Monthly
Calculated
E
BOD, 5 day, 20°C3 C0310
(April 1- October 31)
5.0 mg/L
7.5 mg/L
2/week$
Composite
I and E
BOD, 5 day, 20°C3 C0310
(November 1- March 31)
10.0 mg/L
15.0 mg/L
2/week$
Composite
I and E
Total Suspended Solids3 C0530
30.0 mg/L
45.0 mg/L
2/week$
Composite
I and E
NH3 as N C0610
(Apr 1- Oct 31)
1.0 mg/L
3.0 mg/L
2/week$
Composite
E
NH3 as N C0610
(Nov 1- Mar 31)
2.0 mg/L
6.0 mg/L
2/week$
Composite
E
Fecal Coliform 31616
(geometric mean)
200/100 mL
400/100 mL
2/week"
Grab
E
Dissolved Oxygen 00300
Daily Average >_ 6.0 mg/L
Daily
Grab
E
pH 00400
Between 6.0 and 9.0 Standard Units
Daily
Grab
E
Temperature °C 00010
Monitor and Report
Daily
Grab
E
Total Residual Chlorine 50060
1 1 28 lag/L
Daily
Grab
E
Conductivity (pmhos/cm) 00094
Monitor and Report
Daily
Grab
E
Total Phosphorus (mg/L) C0665
2.0 mg/L (Quarterly Average)
Weekly
Composite
E
TKN (mg/L) 00625
Monitor and Report
Weekly
Composite
E
NO3-N + NO2-N (mg/L) 00630
Monitor and Report
Weekly
Composite
E
Total Nitrogen (mg/L) C0600
Monitor and Report
Weekly
Calculated
E
TN Load 9.10 QM600
QY600
Monitor and Report (lb/month)
22,832 Ib/yr
Monthly
Annually
Calculated
E
Bis (2-ethylhexyl) phthalate (lag/L) 39100
Monitor and Report
Quarterly
Composite
E
Chronic Toxicity6 TGP38
Monitor and Report
Quarterly
Composite
E
Pollutant Scan' NC01
Monitor and Report
Footnote 7
Footnote 7
E
Hardness" -Total as CaCO3 (mg/L) 00900
Monitor and Report
Quarterly
Composite
E
Hardness" -Total as CaCO3 (mg/L) 00900
Monitor and Report
Quarterly
Grab
U
Dissolved Oxygen (mg/L) 00300
Monitor and Report
Variable
Grab
U and D
Temperature °C 00010
Monitor and Report
Variable
Grab
U and D
Conductivity (pmhos/cm) 00094
Monitor and Report
Variablez
Grab
U and D
Fecal Coliform (#/100mL) 31616
(geometric mean)
Monitor and Report
Variablez
Grab
U and D
Footnotes:
The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. See Special Condition A. (7.).
Footnotes continue on the next page.
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Permit NCO025453
Footnotes continued from A. (1.) Effluent Limitations and Monitoring Requirements:
Sample locations I -Influent, E-Effluent, U-Upstream = at NCSR 1700, D-Downstream = (1) NC HWY 42 and
(2) NCSR 1908. Upstream and downstream samples shall be grab samples collected 3/week during
June, July, August, and September and 1/week during the remainder of the year. Instream sampling
requirements are provisionally waived in light of the permittee's participation in the Lower Neuse River
Basin Association. Should participation in the association cease, all instream sampling requirements are
immediately reinstated.
The monthly average effluent BOD5 and Total Suspended Solids concentrations shall not exceed 15% of the
respective influent value (85% removal).
The Division shall consider all effluent total residual chlorine values reported below 50 µg/1 to be in
compliance with the permit. However, the permittee shall continue to record and submit all values
reported by a North Carolina certified laboratory (including field certified), even if these values fall
below 50 µg/l.
For a given wastewater sample, TN = TKN + NO3-N + NO2-N, where TN is Total Nitrogen, TKN is Total
Kjeldahl Nitrogen, and NO3-N and NO2-N are Nitrate and Nitrite Nitrogen, respectively.
Chronic Toxicity (Ceriodaphnia dubia) P/F at 2% with testing in March, June, September, and December.
See Special Condition A. (2.).
The permittee shall perform three effluent pollution scans during the term of this permit. See Special
Condition A. (3.).
Twice per week sampling must occur on any two non-consecutive days during the calendar week.
TN Load is the mass load of TN discharged by the permittee in a period of time. See Special Condition A.
(4.).
Compliance with these limits shall be determined in accordance with Special Condition A. (5.), Annual
Limits for Total Nitrogen.
The permittee shall sample instream hardness upstream of the facility's discharge. The sample shall be
representative of the hardness in the stream. If the permittee is a member of the Monitoring Coalition
Program, sampling for instream hardness may be waived as long as the Monitoring Coalition agrees to
sample hardness at the nearest upstream location, at a minimum frequency of quarterly, and the
permittee has obtained approval from DWR -NPDES Permitting Unit that the upstream station being
monitored by the coalition is representative of the receiving stream for this discharge. The permittee is
responsible for submitting instream hardness test results with its DMRs as results are received from the
coalition. If coalition membership is cancelled or the Monitoring Coalition terminates instream hardness
sampling at the approved station, the permittee will immediately notify the Division and resume
sampling for instream hardness, upstream of its discharge, as required in Section A. (1.). Effluent
hardness shall be performed in conjunction with testing for hardness dependent metals (cadmium,
copper, lead, nickel, silver, and zinc).
(b.) There shall be no discharge of floating solids or visible foam in other than trace amounts.
A.(2.) CHRONIC TOXICITY PERMIT LIMIT (QUARTERLY) [15A NCAC 02B.0200]
The effluent discharge shall at no time exhibit observable inhibition of reproduction or significant
mortality to Ceriodaphnia dubia at an effluent concentration of 2%.
The permit holder shall perform at a minimum, uag rterlmonitoring 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
March, June, September, and December. 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
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Permit NCO025453
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.
All toxicity testing results required as part of this permit condition will be entered electronically using
the Division's eDMR system for the month 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, NC 27699-1621
Or, results can be sent to the email, [e-mail].
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 there 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.
A.(3.) EFFLUENT POLLUTANT SCAN (Municipal POTWs) [G.S.143-215.1(b)]
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: 2021, 2022, and 2023. 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
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Permit NC0025453
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)
Trans-1,2-dichloroethylene
Bis (2-chloroethyl) ether
Chlorine (total residual, TRC)
1,1-dichloroethylene
Bis (2-chloroisopropyl) ether
Dissolved oxygen
1,2-dichloropropane
Bis (2-ethylhexyl) phthalate
Nitrate/Nitrite
1,3-dichloropropylene
4-bromophenyl phenyl ether
Kjeldahl nitrogen
Ethylbenzene
Butyl benzyl phthalate
Oil and grease
Methyl bromide
2-chloronaphthalene
Phosphorus
Methyl chloride
4-chlorophenyl phenyl ether
Total dissolved solids
Methylene chloride
Chrysene
Hardness
1,1,2,2-tetrachloroethane
Di-n-butyl phthalate
Antimony
Tetrachloroethylene
Di-n-octyl phthalate
Arsenic
Toluene
Dibenzo(a,h)anthracene
Beryllium
1,1,1-trichloroethane
1,2-dichlorobenzene
Cadmium
1,1,2-trichloroethane
1,3-dichlorobenzene
Chromium
Trichloroethylene
1,4-dichlorobenzene
Copper
Vinyl chloride
3,3-dichlorobenzidine
Lead
Acid -extractable compounds.
Diethyl phthalate
Mercury (EPA Method 1631E)
P-chloro-m-cresol
Dimethyl phthalate
Nickel
2-chlorophenol
2,4-dinitrotoluene
Selenium
2,4-dichlorophenol
2,6-dinitrotoluene
Silver
2,4-dimethylphenol
1,2-diphenylhydrazine
Thallium
4,6-dinitro-o-cresol
Fluoranthene
Zinc
2,4-dinitrophenol
Fluorene
Cyanide
2-nitrophenol
Hexachlorobenzene
Total phenolic compounds
4-nitrophenol
Hexachlorobutadiene
Volatile organic compounds:
Pentachlorophenol
Hexachlorocyclo- pentad iene
Acrolein
Phenol
Hexachloroethane
Acrylonitrile
2,4,6-trichlorophenol
Indeno(1,2,3-cd)pyrene
Benzene
Base -neutral compounds.
Isophorone
Bromoform
Acenaphthene
Naphthalene
Carbon tetrachloride
Acenaphthylene
Nitrobenzene
Chlorobenzene
Anthracene
N-n itrosodi-n-propyla mine
Chlorodibromomethane
Benzidine
N-nitrosodimethylamine
Chloroethane
Benzo(a)anthracene
N-nitrosodiphenylamine
2-chloroethylvinyl ether
Benzo(a)pyrene
Phenanthrene
Chloroform
3,4 benzofluoranthene
Pyrene
Dichlorobromomethane
Benzo(ghi)perylene
1,2,4-trichlorobenzene
1,1-dichloroethane
Benzo(k)fluoranthene
1,2-dichloroethane
Bis (2-chloroethoxy) methane
Reporting. Test results shall be reported electronically via eDMR or on DWR Form - DMR-PPA-1 (or
on a form approved by the Director) by December 31st of each designated sampling year. The report
shall be submitted to the following address:
NC DEQ/ DWR/ Central Files,1617 Mail Service Center, Raleigh, North Carolina 27699-1617.
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Permit NC0025453
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 122.210)(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.
A.(4.) CALCULATION OF TOTAL NITROGEN LOADS [G.S. 143-215.1(b)]
(a.) The permittee shall calculate monthly and annual TN Loads as follows:
(i.) Monthly TN Load (lb/mo) = TN x TMF x 8.34
where:
TN = the average Total Nitrogen concentration (mg/L) of the
composite samples collected during the month
TMF = the Total Monthly Flow of wastewater discharged during the
month (MG/ mo)
8.34 = conversion factor, from (mg/L x MG) to pounds
(ii.) Annual TN Load (lb/yr) = Sum of the 12 Monthly TN Loads for the calendar year
(b.) The permittee shall report monthly Total Nitrogen results (mg/L and lb/mo) in the discharge
monitoring report for that month and shall report each year's annual results (lb/yr) in the
December report for that year.
A.(5.) ANNUAL LIMITS FOR TOTAL NITROGEN [G.S.143-215.1(b)]
(a.) Total Nitrogen (TN) allocations and TN Load limits for NPDES dischargers in the Neuse River
basin apply on a calendar year basis.
(b.) For any given calendar year, the permittee shall be in compliance with the annual TN Load limit
in this Permit if:
(i.) the permittee's annual TN discharge is less than or equal to its TN Load limit, or
(ii.) the permittee is a co-permittee member of a compliance association.
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Permit NC0025453
(c.) If the permittee is not a co-permittee member of a compliance association and the permittee's
cumulative annual TN discharge exceeds the effective TN Load limit in this permit at any point
during the calendar year, the permittee is in violation of its TN Load limit, and each day of a
continuing violation shall constitute a separate violation.
(d.) The TN Load limit in this Permit (if any) may be modified as the result of allowable changes in
the permittee's TN allocation.
(i.) Allowable changes include those resulting from purchase of TN allocation from the
Wetlands Restoration Fund; purchase, sale, trade, or lease of allocation between the
permittee and other dischargers; regionalization; and other transactions approved by the
Division.
(ii.) The permittee may request a modification of the TN Load limit in this Permit to reflect
allowable changes in its TN allocation. Upon receipt of timely and proper application, the
Division will modify the permit as appropriate and in accordance with state and federal
program requirements.
(iii.) Changes in TN limits become effective on January 1 of the year following permit
modification. The Division must receive application no later than August 31 for changes
proposed for the following calendar year.
(iv.) Application shall be sent to:
NCDWR / NPDES Programs
Attn: Neuse River Basin Coordinator
1617 Mail Service Center
Raleigh, NC 27699-1617
(e.) If the permittee is a member and co-permittee of an approved compliance association, its TN
discharge during that year is governed by that association's group NPDES permit and the TN
limits therein.
(i.) The permittee shall be considered a Co-permittee Member for any given calendar year in
which it is identified as such in Appendix A of the association's group NPDES permit.
(ii.) Association roster(s) and members' TN allocations will be updated annually and in
accordance with state and federal program requirements.
(iii.) If the permittee intends to join or leave a compliance association, the Division must be
notified of the proposed action in accordance with the procedures defined in the
association's NPDES permit.
(A) Upon receipt of timely and proper notification, the Division will modify the permit as
appropriate and in accordance with state and federal program requirements.
(B) Membership changes in a compliance association become effective on January 1 of the
year following modification of the association's permit.
(f.) The TN monitoring and reporting requirements in this Permit remain in effect until expiration of
this Permit and are not affected by the permittee's membership in a compliance association.
A.(6.) TOTAL NITROGEN ALLOCATIONS AND OFFSET CREDITS [G.S.143-215.1(b)]
(a.) The following table lists the Total Nitrogen (TN) allocations and offset credits assigned to,
acquired by, or transferred to or from the permittee in accordance with the Neuse River nutrient
strategy (15A NCAC 02B .0700) and the status of each as of permit issuance. These allocations and
credits are not enforceable limits nor do they supersede any TN limit(s) established elsewhere in
this permit or in the NPDES permit of a compliance association of which the permittee is a Co-
permittee Member.
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Permit NCO025453
ALLOCATION/ CREDITS
ALLOCATION/
AMOUNT'
CREDITS TYPE
SOURCE
DATE
STATUS
Estuary
Discharge
(Ib/yr)
(Ib/yr)
Base Allocation
Assigned by Rule z
12/7/97; 4/1/03
10,700
21,400
Active
Supplemental
Purchased from South Granville
7/5/06
3,668
7,336
Reserve
Allocation
WSA (NC0026824)
1,645
3,290
Mixed
Supplemental
Purchased from UNIFI-Kinston
8/30/2007
716
1,432
Active
Allocation
(NC0003760)
929
1,858
Reserve
Purchased from
TN Offset Credits
RS-Flat Swamp, LLC (Flat Swamp
9/4/2020
15,908 3-4
31,8164
Reserve
Mitigation Bank)
TOTAL
31,921
63,842
Mixed
11,416
22,832
Active
20,505
41,010
Reserve
Footnotes:
1. Transport Factor = 50%. Values are displayed to the nearest pound per year.
2. 15A NCAC 02B .0713 (formerly 02B .0234)
3. The Permittee purchased offset credits in the amount of 715,858.18 lb TN, or 23,861.94 lb/yr for 30
years. To satisfy the 1.5:1 uncertainty ratio (Rule .0713),15,907.96 lb/yr of credits are available to the
Permittee, and the remaining 7,953.98 lb/yr are set aside for the benefit of the estuary and are not
available to offset any activity, whether point source or nonpoint source in nature.
4. The Mitigation Bank is located in the 100% transport zone per the 1999 Neuse Estuary TMDL. In
accordance with S.L. 2020-18, the 15,907.96 lb/yr of available credits acquired by the Permittee are, for
the purposes of this permit, equivalent to 31,815.92 lb/yr for 30 years at the Permittee's discharge
location.
(b.) Any addition, deletion, or modification of the listed allocations and credits (other than
typographical errors) or any change to Active status of any of the listed allocations and credits
shall be considered a major modification of this permit and shall be subject to the public review
process afforded such modifications under state and federal rules.
A.(7.) ELECTRONIC REPORTING OF MONITORING REPORTS [G.S.143-215.1(b)]
Federal regulations require electronic submittal of all discharge monitoring reports (DMRs) and
program reports. The final NPDES Electronic Reporting Rule was adopted and became effective on
December 21, 2015.
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 Requirements [Supersedes Section D. (2.) and Section E. (5.) (a)]
The permittee shall report discharge monitoring data electronically using the NC DWR's Electronic
Discharge Monitoring Report (eDMR) internet application.
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Permit NC0025453
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 DEQ / Division of Water Resources / Water Quality Permitting Section
ATTENTION: Central Files
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. See "How to Request a Waiver from Electronic Reporting' section
below.
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.
Starting on December 21, 2020, the permittee must electronically report the following compliance
monitoring data and reports, when applicable:
Sewer Overflow/Bypass Event Reports;
Pretreatment Program Annual Reports; and
Clean Water Act (CWA) Section 316(b) Annual Reports.
The permittee may seek an electronic reporting waiver from the Division (see "How to Request a
Waiver from Electronic Reporting" section below).
2. Electronic Submissions
In accordance with 40 CFR 122.41(1) (9), the permittee must identify the initial recipient at the time
of each electronic submission. The permittee should use the EPA's website resources to identify the
initial recipient for the electronic submission.
Initial recipient of electronic NPDES information from NPDES-regulated facilities means the entity
(EPA or the state authorized by EPA to implement the NPDES program) that is the designated
entity for receiving electronic NPDES data [see 40 CFR 127.2(b)].
EPA plans to establish a website that will also link to the appropriate electronic reporting tool for
each type of electronic submission and for each state. Instructions on how to access and use the
appropriate electronic reporting tool will be available as well. Information on EPA's NPDES
Electronic Reporting Rule is found at:
https:/ /www.federalregister.gov/documents/2015/10/22/2015-24954/national-pollutant-
discharge-elimination-system-npdes-electronic-reporting-rule
Electronic submissions must start by the dates listed in the "Reporting Requirements" section
above.
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Permit NC0025453
3. How to Request a Waiver from Electronic Reporting
The permittee may seek a temporary electronic reporting waiver from the Division. To obtain an
electronic reporting waiver, a permittee must first submit an electronic reporting waiver request to
the Division. Requests for temporary electronic reporting waivers 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 submitting monitoring data and reports. The duration of a
temporary waiver shall not exceed 5 years and shall thereupon expire. At such time, monitoring
data and reports shall be submitted electronically to the Division unless the permittee re -applies for
and is granted a new temporary electronic reporting waiver by the Division. Approved electronic
reporting waivers are not transferrable. Only permittees with an approved reporting waiver
request may submit monitoring data and reports on paper to the Division for the period that the
approved reporting waiver request is effective.
Information on eDMR and the application for a temporary electronic reporting waiver are found on
the following web page:
http://deq.nc.gov/about/divisions/water-resources/edmr
4. Si ng atory Requirements [Supplements Section B. (11.) (b) and Supersedes Section B. (11.) (d)1
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://deq.nc.gov/about/divisions/water-resources/edmr
Certification. Any person submitting an electronic DMR using the state's eDMR system shall make
the following certification [40 CFR 122.221. 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."
5. Records Retention [Supplements Section D. (6.)]
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
122.411.
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Fact Sheet
NPDES Permit No. NCO025453
Permit Writer/Email Contact: Mike Templeton, [e-mail], 919-707-3603
Date: September 15, 2020
Division/Branch: NC DWR/ WQ Permitting Section/ NPDES Permitting
Fact Sheet Template: Version 09Jan2017
Permitting Action:
❑ Renewal
❑ Renewal with Expansion
❑ New Discharge
❑x Modification
1. Basic Facility Information
Facility Information
Applicant/Facility Name:
Town of Clayton/Little Creek WRF
Applicant Address:
PO Box 879, Clayton, North Carolina
Facility Address:
1000 Durham Street Extension, Clayton, NC
Permitted Flow:
2.5 MGD
Facility Type/Waste:
MAJOR Municipal; 95% domestic, 5% industrial
Facility Class:
Class 4
Treatment Units:
Mechanical bar screens & grit removal, influent pump station,
anaerobic basin, anoxic tanks, oxidation basins, clarifiers, tertiary
filters, UV disinfection with backup chlorination/dechlorination,
aerated sludge digester, sludge holding tank, sludge thickener,
non -potable reclaimed water system
Pretreatment Program
(Y/ N)
Yes
County:
Johnston
Region
Raleigh
Permit Action
By its letter of June 16, 2020, signed by James Warren, WWTP Operations Superintendent, the
Town of Clayton requested modification of its NPDES permit to reflect its purchase of nitrogen
offset credits, then pending. The Division reviewed the request and supporting materials and
made a tentative determination to modify the permit as requested. Public notice was published
in The News and Observer on July 23, 2020, inviting public comment. No comments were received
from the general public. The Division's Public Water Supply Section provided its concurrence
Page 1 of 7

the permit as written, and Restoration Systems/ FR Flat Swamp and our Nutrient Offset and
Riparian Buffer Mitigation Banking Program suggested changes and clarification.
The purpose of this modification is to document the purchase of nutrient offset credits in the
Towri s permit. No limits are modified as a result. The credits are added to the listing of
allocations and credits in Condition A.(6.) of the permit and are recorded as being held in
reserve. The offset credits will be activated and used to increase the Towri s TN limit for future
expansion. That change will also be subject to public review in accordance with NPDES
regulations.
Facility Background
The Little Creek facility serves a population of 19,102 residents and operates a pretreatment
program with two pharmaceutical Categorical Industrial Users, Novo Nordisk and Grifols.
Currently, Grifols discharges to Johnston County's WWTP. Novo Nordisk's flow to Little Creek
WWTP was 0.076 MGD. Clayton has agreements with Johnston County and Raleigh's Neuse
River WWTP to divert up to 1.3 MGD and 1.0 MGD to those plants respectively. Clayton also
operates a reclaimed water system and land applies up to 237,840 GPD under permit
WQ0022224. I&I was reported at 438,000 GPD.
The Towri s permit was last reissued December 6, 2019, and became effective January 1, 2020.
2. Receiving Waterbody Information:
Receiving Waterbody Information
Outfalls/Receiving Stream(s):
Outfall 001- Neuse River
Stream Segment:
27-41.3
Stream Classification:
WS-IV; NSW, CA
Drainage Area (mi2):
1,150
Summer 7Q10 (cfs)
186 (regulated)
Winter 7Q10 (cfs):
186 (regulated)
30Q2 (cfs):
186 (regulated)
Average Flow (cfs):
186 (regulated)
IWC (% effluent):
1.6
303(d) listed/parameter:
No
Subject to TMDL/parameter:
Yes- Subject to Neuse nutrient rule 15A NCAC 02B
.0234, Statewide Mercury TMDL
Subbasin/HUC:
030402/03020201
USGS Topo Quad:
E25NW/ NW Clayton
3. Effluent Data Summary
Effluent nutrient data for the period May 2014 through December 2018 is as follows:
Page 2 of 7

Table 1. Effluent Data Summary
Parameter
Units
Average
Max
Min
Permit Limit
Flow
MGD
1.55
5.82
0.46
2.5
TN
mg/ L
4.14
13.08
1.24
Kjeldahl Nitrogen
mg/L
1.24
6.04
0.2
Nitrate+Nitrite
mg/ L
2.89
11.24
0.48
TN Monthly
lb/mo
1,627
3,308
630
TN Yearly
lb/yr
19,903
20,901
18,472
22,832
TP
mg/L
1.08
6.53
<0.04
TP Quarterly Average
I mg/L
11.08
11.65
1 0.40
2.0
MA -Monthly Average, WA -Weekly Average, DM -Daily Maximum
4. Instream Data Summary
The Permittee is a member of the Lower Neuse Basin Association (LNBA), which performs
ambient monitoring on behalf of its members per its Memorandum of Agreement with the
Division of Water Resources.
5. Compliance Summary
Compliance with Nutrient Limitations:
Clayton is a co-permittee member of the Neuse River Compliance Association and is subject to
the combined Total Nitrogen (TN) limit in the Associations group permit. The Association has
consistently complied with its TN limit since the group permit became effective in calendar year
2003. The Town is not subject to the TN limit in its individual permit as long as the Association
complies with the group limit; nevertheless, it has consistently complied with its own
individual allocation.
6. Water Quality -Based Effluent Limitations (WQBELs)
Neuse River Nitrogen TMDL and Nutrient Management Strategy
The Neuse River estuary has an extensive history of nutrient -related water quality impacts and
was classified as Nutrient Sensitive Waters in 1988. Nutrient Management Strategy rules were
first adopted in December 1997 and modified in 2000 and 2020. The wastewater discharge rule,
15A NCAC 2B .0713 (formerly .0234), established requirements for control of Total Nitrogen
(TN) from point source discharges. It requires TN limits for all dischargers with a permitted
capacity of 0.5 MGD or greater and allows the transfer of allocation among the Neuse
dischargers so long as the total of estuary allocations and loads do not exceed those allowed in
the 1999 TN TMDL. The rule also sets technology -based limits for Total Phosphorus (TP).
The Town of Clayton was assigned a Total Nitrogen (TN) allocation of 21,400 lb/yr at end -of -
pipe (10,700 lb/yr at the estuary), which was the basis for its first TN discharge limit, in
accordance with the rule. Based on its location relative to the estuary, the facility was assigned a
transport factor of 50%, as its allocation numbers indicate.
Page 3 of 7

The wastewater rule also provides a group compliance option through which interested
dischargers can work to comply with a collective TN limit. Clayton is a co-permittee member of
the Neuse River Compliance Association, whose group NPDES permit, NCC000001, was last re-
issued December 12, 2018. Co-permittee members are deemed to be in compliance with the TN
limits in their individual permits and instead subject to the group limit established in the group
permit. The group TN limit is the sum of the members' active estuary allocations.
The Towri s TN active discharge allocation is 22,832 lb/year, which, after transport losses in the
river, is equivalent to 11,4161b/yr at the estuary. The allocation includes the Towri s original
allocation plus supplemental allocations purchased from other permittees in the basin.
The Town has experienced significant growth since the Neuse strategy was established and, as a
result, was authorized to expanded to 2.5 MGD in its 2006 permit. Anticipating continued
growth, it acquired additional allocation from SGWASA (NC0026824) and UNIFI-Kinston
(formerly, and once again, DuPont -Kinston, NC0003760). The combined allocations exceed the
limit the strategy would allow for the expanded facility, and the excess is held in reserve until it
can be used for future expansions. Details are provided in Table 2.
Table 2. Town of Clayton - Current TN Allocations
ALLOCATION AMOUNT
SOURCE
STATUS
Estuary
Discharge
(Ib/yr)
(Ib/yr)
Assigned by Rule
10,700
21,400
Active
J15A NCAC 02B .0234)
Purchased from
3,668
7,336
Reserve
South Granville WSA (NC0026824)
1,645
3,290
Mixed
Purchased from
716
1,432
Active
UNIFI-Kinston (NC0003760)
929
1,858
Reserve
TOTAL
16,013
32,026
Mixed
11,416
22,832
Active
4,597
9,194
Reserve
Purchase of Nutrient Offset Credits
The Town of Clayton plans to request approval of an expansion to 5.0 MGD in the near future,
in order to meet its growing wastewater treatment needs. Its TN allocations in Table 2,
including those held in reserve, would be equivalent to 2.1 mg/L TN at the increased flow. The
commonly accepted limit of economically achievable treatment technology is 3 mg/L; thus, the
Towri s current allocations are not sufficient for the planned expansion.
To meet the additional needs, the Town entered into an agreement with RS Flat Swamp, LLC to
purchase nutrient offset credits in accordance with the Neuse River nutrient strategy. RS Flat
Swamp is the Bank Sponsor for the RS Flat Swamp Buffer & Nutrient Offset Mitigation Bank, a
mitigation project undertaken to generate nutrient offset credits. The transaction was conducted
according to procedures of the Divisions Nutrient Offset and Riparian Buffer Mitigation
Banking Program.
Page 4 of 7

■ On November 7, 2019, the Town and Restoration Systems submitted a Letter of Intent to
enter into an agreement for the purchase of offset credits.
■ On March 17, 2020, Restoration Systems issued a Statement of Nutrient Offset Credit
Availability ("Statement") confirming that it had generated and was authorized to sell
credits under the approved Mitigation Banking Instrument, which became effective
December 20, 2019. (Note: Normally, the Statement of Availability precedes the Sales
Agreement.) The Statement certifies that credits in the amount of 715,858.18 lbs (or 23,862.94
lb/yr for 30 years) had generated and released and were currently on hold specifically for
sale to the Town of Clayton for the planned expansion. The Statement was approved by the
Mitigation Banking program, also on March 17, 2020.
■ When no public comments were received during the permit's 30-day comment period, the
Town executed the purchase and made full payment for the credits. Restoration Systems
completed a Nutrient Offset Credit Transfer Certificate (bill of sale) for the transfer on
September 4, 2020.
■ The Division issued the modified permit upon receipt of the NOCTC.
Calculation of Applicable Offset Credits
Consideration of Transport Losses. The transfer of nutrient allocations among point source
dischargers in a river basin is routinely adjusted to account for differences in delivery rates
("transport factors") in different parts of the basin. In the case of nonpoint source controls, the
Divisions nutrient strategies have required that offset credits generated in the basin be applied
within the same hydrologic unit or subbasin in which they were generated. Each approach
ensures that differences in transport of nutrients at two different locations does not result in an
increased nutrient load to the waterbody of concern. Transport factors have not been employed
in nonpoint source transactions.
In June 2020, the NC General Assembly ratified, and the Governor signed, Senate Bill 315 (S.L.
2020-18), known as the Farm Bill. Section 15.(a) of the bill required that transport factors be
applied when transferring offset credits to wastewater permits. Section 15.(b) limited its
applicability to local governments "with a customer base of fewer than 15,000 connections", in
effect, the Town of Clayton.
Calculations. The Town purchased 715,858.18 lb of TN credits, equivalent to 23,862.94 lb/yr of
credits for 30 years. The Neuse wastewater rule,15A NCAC 02B .0713 (formerly 02B .0234)
specifies an uncertainty ratio of 1.5:1, meaning that the Town must purchase 1.5 lb of credits for
every pound required for its discharge. In other words, the Town can utilize 1/1.5, or two-
thirds of the credits it is purchasing in this transaction:
2/3 of 23,862.94 lb/yr = 15,907.96 lb/yr available TN credits
The remaining 7,953.98 lb/yr of credits are set aside to satisfy the uncertainty provision of Rule
.0713 and cannot be applied to offset any activity, whether point source or nonpoint source in
nature.
The transport factor for the area in which the Flat Swamp Mitigation Bank is located is 100%;
that for the Town of Clayton discharge is 50%. Per the 2020 Farm Bill, the amount of offset
credits available at the Towri s point of discharge is:
15,907.96 lb/yr (at estuary) x 100%/ 50% = 31,815.92 lb/yr (at point of discharge)
Page 5 of 7

The Towri s TN allocations and the new offset credits are listed in Table 3. The new credits also
exceed the allowable technology -based limit for the existing facility, per the Rule, and so will
also be held in reserve pending future expansion.
Table 3. Town of Clayton - TN Allocations and Offset Credits
ALLOCATION/ CREDITS
AMOUNT
SOURCE
STATUS
Estuary
Discharge
(Ib/yr)
(Ib/yr)
Assigned by Rule
10,700
21,400
Active
Purchased from South Granville
3,668
7,336
Reserve
WSA (NC0026824)
1,645
3,290
Mixed
Purchased from UNIFI-Kinston
716
1,432
Active
(NC0003760)
929
1,858
Reserve
Purchased from
RS-Flat Swamp, LLC Flat
15,908
31,816
Reserve
Swamp Mitigation Bank
TOTAL
31,921
63,842
Mixed
11,416
22,832
Active
20,505
41,010
Reserve
7. Technology -Based Effluent Limitations (TBELs)
Not applicable to this permit action.
8. Antidegradation Review (New/Expanding Discharge):
Not applicable to this permit action.
9. Antibacksliding Review:
Not applicable to this permit action.
10. Monitoring Requirements
Monitoring requirements are not affected by this permit action.
11. Electronic Reporting Requirements
Electronic reporting requirements are not affected by this permit action.
12.Summary of Proposed Permitting Actions:
Page 6 of 7

The proposed modification will record the Towri s purchase of nutrient offset credits. The
credits will be held in reserve but may be applied to increase its TN limit upon with future
expansions in accordance with Rule 02B .0713. The modification makes no substantive changes
to the effluent limitations, monitoring requirements, or other conditions of the permit.
13. Public Notice Schedule:
Permit to Public Notice: July 23, 2020
Close of Comment Period: August 24, 2020
Per 15A NCAC 02H .0109 & .0111, the Division published notice of the permit action in The
News and Observer and invited comments for a period of 30 days.
We received no response from the general public. However, the Divisions Public Water Supply
Section provided its concurrence the permit as written, and Restoration Systems/ FR Flat
Swamp and our Nutrient Offset and Riparian Buffer Mitigation Banking Program suggested
changes and clarification.
Minor changes were made in response. Conversion of the offset credits from 30-year to
permanent will be completed once the Division decides on the process for it.
14. Fact Sheet Addendum:
After the close of the public comment period, RS Flat Swamp, LLC, provided a signed Nutrient
Offset Credit Transfer Certificate documenting that, as of September 4, 2020, the Town had paid
in full for the purchase of the offset credits being added to the permit. The Division accepts this
as sufficient for the issuance of the modification.
15. Fact Sheet Attachments:
Not applicable.
Page 7 of 7