NC0083551_Draft Permit_20240528

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
RICHARD E. ROGERS, JR.
Director
Mr. David Mohr, Chief Operations Officer
Onslow Water and Sewer Authority
228 Georgetown Road
Jacksonville, NC 28540
Dear Permittee:
don slwrla,
NORTH CAROLINA
Environmental Quality
May 28, 2024
Subject: Draft NPDES Permit NCO083551
Dixon WTP
Grade I Physical Chemical WPCS
Onslow County
The Division has reviewed your request to renew the subject permit. Enclosed with this letter is a copy
of the draft permit for your facility. Please review this draft carefully to ensure your thorough
understanding of the information, conditions, and requirements it contains.
The draft permit includes the following significant changes from the existing permit:
➢ Updated the maximum, monthly average wastewater discharge on the Supplement to Permit
Cover Sheet
➢ Added the chemical additives list at the water treatment plant to the Supplement to Permit Cover
Sheet
➢ Added the facility grade to Part I. Section A. (1.).
➢ Based on the results of the reasonable potential analysis, monitoring for Arsenic was removed
from the table in Part I. A. (1).
➢ Added a monthly average flow limit to the effluent table in Part I. Section A. (1) per the updated
water treatment permitting strategy
➢ Added parameter units to the effluent table in Part I. Section A. (1.).
➢ Added parameters TKN and NO2-N + NO3-N to the effluent table in Part I. Section A. (L).
➢ Updated Whole Effluent Toxicity testing language in Part I. A. (2).
➢ Removed Special Condition A. (4.) Discharge Alternatives Evaluation from the previous permit
based on the facility's compliance history.
➢ Updated eDMR language for electronic data submission in Part I. A. (4).
➢ Updated the map.
The NPDES standard conditions (Parts II, III, and IV) that are a part of the permit are not included in
this draft document (cover, map, and Part I). The conditions are the same as in your current permit
except that agency and division names have been updated. The latest version is available at
https://bit.ly/3k5NFaL and can be viewed online or downloaded as a PDF file.
With this notification, the Division will solicit public comment on this draft permit by publishing a
notice in newspapers having circulation in the general Onslow County area, per EPA requirements.
North Carolina Department of Em ironmental Quality I Division of Water Resources
512 North Salisbury- Street 1 1617 Mail Service Center I Raleigh. North Carolina 27699-1617
�\ �./ 919.707.9000

Page 2 of 2
NPDES Permit NCO083551
Please provide your comments, if any, to me at the e-mail address below no later than 30 days
after receiving this draft permit.
Following the 30-day public comment period, the Division will review all pertinent comments and take
appropriate action prior to issuing a final permit.
If you have questions concerning the draft, please contact me at carol ine.robinsongdeq.nc.gov.
Sincerely,
Environmental Specialist II
NPDES Compliance and Expedited Permitting
cc: NPDES Files
Wilmington Regional Office
Aquatic Toxicology Unit
Operator Certification Program
Shellfish Sanitation

NPDES Permit NCO083551
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENTAL QUALITY
DIVISION OF WATER RESOURCES
PERMIT
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
(NPDES)
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,
Onslow Water and Sewer Authority
is hereby authorized to discharge wastewater from a facility located at the
Dixon WTP
6661 Wilmington Highway
Holly Ridge
Onslow County
to receiving waters designated as an unnamed tributary to Stones Creek within the White Oak River Basin
and 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
This permit and authorization to discharge shall expire at midnight on July 31, 2029.
If the permittee intends to continue to discharge at the facility beyond the term of this permit, a renewal
application must be submitted no later than February 1, 2029 (180 days before the expiration of this
permit).
Signed this day
John E. Hennessy, Section Chief Regional Operations
Division of Water Resources
By Authority of the Environmental Management Commission
Page 1 of 8

NPDES Permit NCO083551
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.
Onslow Water and Sewer Authority
is hereby authorized to:
1. Continue to operate a water treatment plant with a discharge of greensand filter and ion exchange
backwash, and reverse osmosis reject wastewater. This water treatment plant currently has a design
potable flowrate of 4 MGD and a maximum, monthly average wastewater discharge of 0.511 MGD.
This facility is located at 6661 Wilmington Highway in Holly Ridge in Onslow County. Water and
wastewater treatment consists of
• Nine (9) greensand filters
• Six (6) ion exchange softeners
• Three (3) 1MG reverse osmosis skids with thirty (30) membrane vessels per skid
• Three (3) 915,000 gallon settling basins
With potential to discharge
• Potassium Permanganate
• Sodium Hydroxide
• Anti-Scalant
• Hydrofluorosilicic acid
• Ortho Phosphate
• Sodium Hypochlorite
• Chlorination
2. Discharge from said treatment works at the location specified on the attached map, via Outfall 001,
into an unnamed tributary to Stones Creek [Stream Segment: 19-30-3], a waterbody currently
classified SA-HQW, PNA waters within Subbasin 03-05-02 [HUC: 030203020209] of the White Oak
River Basin.
Page 2 of 8

NPDES Permit NCO083551
PART I.
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
[15A NCAC 02B .0400 et seq., 02B .0500 et seq.]
Grade I Physical -Chemical WPCS [15A NCAC 08G .0306]
During the period beginning on the effective date of this permit and lasting until expiration, the
Permittee is authorized to discharge from Outfall 001. Such discharges shall be limited and monitored'
by the Permittee as specified below:
EFFLUENT CHARACTERISTICS
(Parameter Codes)
LIMITS
MONITORING REQUIREMENTS
Monthly
Average
Daily
Maximum
Measurement
Fre uenc
Sample
Type
Sample
Location
Flow (MGD) (50050)
0.59 MGD
Continuous
Recording
E
Salinityth 00480
Monitor & Report
MonthlyComposite
E
Salinityth00480
Monitor & Report
MonthlyGrab
U, D
Conductivityohms/cm 00094
Monitor & Report
MonthlyCom
osite
E
Conductivity ohms/cm 00094
Monitor & Report
Monthly
Grab
U, D
Total Dissolved Solids (70295)
m
Monitor & Report
Monthly
Composite
E
Dissolved Oxygen m 00300
Monitor & Report
Monthly
Grab
E, U, D
H standard units 00400
6.8 s.0 < H < 8.5 s.u.
2/Month
Grab
E
H standard units 00400
Monitor & Report
Monthly
Grab
U D
Total Residual Chlorines (50060)
13 µg/L
2/Month
Grab
E
Total Suspended Solids (C0530)
m
10.0 mg/L
15.0 mg/L
2/Month
Composite
E
Turbidity TU 00070
Monitor & Report
2/Month
Grab
E
Total Chloride (mg/L) 00940
Monitor & Report
Monthly
Composite
E
Total Manganese 01055
Monitor & Report
Monthly
Composite
E
Total Zinc 01092
42.8 47.6
Monthly
Composite
E
Total Copper L 01042
Monitor & Report
Quarterly
Composite
E
Total Lead 01051
Monitor & Report
Quarterly
Composite
E
TKN m a 00625
Monitor & Report
6uarterfy
Composite
E
NO2-N + NOs-N (mg/L) a 00630
Monitor & Report
Quarterly
Composite
E
Total Nitrogen m a C0600
Monitor & Report
Quarterly
Calculated
E
Total Phosphorus m C0665
Monitor & Report
Quarterly
Composite
E
Ammonia Nitrogen' (C0610)
m
Monitor & Report
Monthly
Composite
E
Whole Effluent Toxicity (TGE3E)
Monitoring 6
Monitor & Report
Quarterly
Composite
E
Footnotes:
1. The permittee shall submit discharge monitoring reports electronically using the Division's eDMR
application system [see A. (4)].
2. E = Effluent; U = Upstream at least 100 feet upstream from the outfall; D = Downstream at least 100 feet
downstream from the outfall.
Page 3 of 8

NPDES Permit NCO083551
3. Limit and monitor only if the facility adds chlorine or chlorine derivatives to water that is eventually
discharged. The Division shall consider all effluent TRC values reported below 50 µg/L 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.
4. For a given wastewater sample, TN = TKN + NO2-N + NO3-N, where TN is Total Nitrogen, TKN is Total
Kjeldahl Nitrogen, and NO2-N and NO3-N are Nitrite and Nitrate Nitrogen, respectively.
5. Ammonia Nitrogen should be monitored if the Permittee uses chloramines (adds ammonia to chlorinated
water) for secondary disinfection prior to backwashing.
6. Acute Toxicity 24-hr Pass/fail Monitoring with Mysid shrimp (Mysidopsis bahia) at 90% in January,
April, July, and October. See Special condition A. (2) for details.
ALL SAMPLES COLLECTED SHOULD BE FROM A REPRESENTATIVE DISCHARGE
EVENT.
THERE SHALL BE NO DISCHARGE OF FLOATING SOLIDS OR VISIBLE FOAM IN
OTHER THAN TRACE AMOUNTS.
A. (2.) ACUTE TOXICITY PASS/FAIL MONITORING (QUARTERLY)
[15A NCAC 02B .0200] [15A NCAC 02B .0500 et seq.]
The permittee shall conduct acute toxicity tests on a quarterly basis using protocols defined in the North
Carolina Procedure Document entitled "Pass/Fail Methodology For Determining Acute Toxicity In A
Single Effluent Concentration" (Revised -December 2010, or subsequent versions). The monitoring shall
be performed as a Mysid Shrimp (Mysidopsis bahia) 24-hour static test. The effluent concentration at
which there may be at no time significant acute mortality is 90% (defined as treatment two in the
procedure document). The tests will be performed during the months of January, April, July, and
October. 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.
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 it was performed, using the parameter code
TGE3E. Additionally, DWR Form AT-2 (original) is to be sent to the following address:
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.
Page 4 of 8

NPDES Permit NC0083551
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, then
monthly monitoring will begin immediately. Upon submission of a valid test, this monthly test
requirement will revert to quarterly in the months specified above.
Should any test data from either these monitoring requirements 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 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.
USE OF A DIFFERENT TEST ORGANISM
The permittee may request the use of a different test organism upon documentation that the alternate test
organism would provide an equal or greater level of protection and is appropriate based on the
characteristics of the discharge and receiving stream. Such documentation would consist of one of the
following:
1. For saltwater classified streams, a fathead minnow may be assigned as the acute testing species if
the salinity of the receiving stream at the point of discharge is <5 ppt throughout the tidally
influenced cycle. This determination may be based on the best professional judgment of DWQ
staff or data collection provided by the permittee and approved by DWQ staff. This evaluation
should include vertical profiles of salinity/conductivity measurements at both high tide and low
tide over several 24 hr cycles.
2. Three consecutive "side -by -side" tests with results indicating that the alternate test organism is as
or more sensitive to the facility's effluent. Each test series would consist of two separate toxicity
tests conducted on the same sample of effluent with the length of exposure specified by the permit,
the only difference between the tests being the organism used.
3. An alternate plan developed by the permittee and approved by the Aquatic Toxicology Unit that
demonstrates an equal level of protection is offered by the test organism.
For items 2 and 3, it must also be demonstrated that viable and standardized culture techniques are
available for that organism and standardized testing methodologies have been developed and
validated. This demonstration should meet guidance provided by EPA in Section 6 of EPA-821-R-02-
Page 5 of 8

NPDES Permit NCO083551
012, Short Term Methods for Estimating the Acute Toxicity of Effluents and Receiving Waters to
Freshwater Organisms. Fifth Edition, 2002. Requests to use a different test organism and supporting
documentation should be sent to NC DWQ, ESS at the address listed above.
A. (3.) PERMIT RE -OPENER: WHOLE EFFLUENT TOXICITY MONITORING
[G.S. 143-215.1(b)]
Whole Effluent Toxicity monitoring results indicating aquatic toxicity failure may result in the Division
of Water Resources re -opening this permit to add a limit for Whole Effluent Toxicity, or requesting by
letter that further action be taken to address toxicity failures. Mitigative actions include additional
testing and/or toxicity identification/reduction evaluations to determine the cause(s) of the effluent
toxicity and measures required to achieve passing effluent toxicity results.
A. (4.) ELECTRONIC REPORTING OF DISCHARGE MONITORING REPORTS
[NCGS 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.)
• Section D. (2.)
• Section D. (6.)
• Section E. (5.)
Signatory Requirements
Reporting
Records Retention
Monitoring Reports
1. Reporting Requirements [Supersedes Section D. (2.) and Section E. (5.) (a)1
The permittee shall report 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. The eDMR system may be accessed at:
https://deg.nc.gov/about/divisions/water-resources/edmr.
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 following address:
NC DEQ / Division of Water Resources / Water Quality Permitting Section
ATTENTION: Central Files
Page 6 of 8

NPDES Permit NC0083551
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
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, 2025, 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-elim ination-system-nodes-electronic-reportin g-rule
Electronic submissions must start by the dates listed in the "Reporting Requirements" section above.
3. How to Request a Waiver from Electronic Resorting
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
Page 7 of 8

NPDES Permit NC0083551
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://deg.nc.g_ov/about/divisions/water-resources/edmr
4. Signatory Requirements [Supplements Section B. (11.) (b) and Supersedes Section B. (11.)
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://deg.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 122.22]. 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. "
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 122.41 ].
Page 8 of 8

-� f�I v L
1
_ bid
WA
=� `JDiixon.
-1�6- -kid 17 +
Approximate
Facility Location
S
Outfall001
. _ - s .rt
/Zrr`
t p -
r
ti--
NCO083551— Dixon WTP
Onslow Water and Sewer Authority
Receiving Stream: UT to Stones Creek Stream Segment: 19-30-3
Stream Class: SA; HQW-PNA Sub -Basin: 03-05-02
Drainage Basin: White Oak HUC: 0302030202
Latitude: 34' 34' 25" N Long: 77° 28' 13" W
71 nL
N
4
Facility
Location
Onslow County
./V� Map not to scale