NC0088285_Draft Permit_20250909

JOSH STEIN
Governor
D. REID WILSON
5ecrrmry
RICHARD E. ROGERS, JR.
Dlrerlor
NORTH CAROLINA
Envillr ntal Qualty
September 9, 2025
ATTN: Jessee Walker, Operations Supervisor
City of Raleigh
P.O. Box 590
Raliegh, NC 27602 Subject: Draft of NPDES Permit NCO088285
Dempsey E. Benton WTP
Grade I Physical Chemical WPCS
Wake County
Dear Mr. Walker,
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 a thorough understanding
of the information, conditions, and requirements it contains.
The draft permit renewal includes the following significant changes from the draft permit
previously sent to you on July 9, 2025:
• The required Whole Effluent Toxicity has been corrected to an Acute toxicity limit at 90% using
Fathead Minnow (Pimephales promelas) based on the 1999 Toxicity Testing Guidance for
outfalls to lakes. See section A. (L) and Section A. (2.).
• The expiration date has been updated.
Please note that Swift Creek (Lake Benson) is listed as an impaired waterbody on the North Carolina
303(d) Impaired Waters List. Addressing impaired waters is a high priority with the Division, and
instream data will continue to be evaluated. If there is noncompliance with this permit's effluent limits
and stream impairment can be attributed to your facility, then mitigative measures may be required.
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
hops://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 Wake County area, per EPA requirements. Please
provide your comments, if any, to me at the address below no later than 30 days after receiving
this draft permit. Your written comments are welcome, but they are not mandatory.
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 [phone] or via e-mail at [e-mail].
North Carolina Department of Environmental Quality I Dlvlslon of Water Resources
512 North Salisbury Street 1 1618 Mail Service Center I Raleigh, North Carolina 27699-1618
919.707.9190

Sincerely,
� taa�'
Sara Bassett
Environmental Specialist I
NPDES Compliance and Expedited Permitting
cc: NPDES File
Raleigh Regional Office [Laserfiche]
Operator Certification Program [Laserfiche]
DRW Aquatic Toxicology Branch [Laserfiche]
Public Water Supply [Laserfiche]

NPDES PermitNCO088285
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, the
City of Raleigh
is hereby authorized to discharge wastewater from a facility located at the
Dempsey E. Benton WTP
2315 Benson Road
Garner
Wake County
to receiving waters designated as Lake Benson in the Neuse River Basin in accordance with effluent
limitations, monitoring requirements, and other applicable 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 October 31, 2030.
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 May 4, 2030 (180 days before the expiration of this permit).
Signed this day
Caroline Robinson
NDPES Compliance and Expedited Permitting Unit Supervisor
Division of Water Resources
By Authority of the Environmental Management Commission
Page 1 of 8

NPDES Permit NCO088285
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 City of Raleigh
is hereby authorized to:
Continue to operate a conventional water treatment plant with a discharge of wastewaters from
treated filter backwash. Backwash is currently recycled to the raw water line after treatment. This
water treatment plant currently has a design potable flowrate of 16 MGD and a designed
wastewater discharge of 4.0 MGD. This facility is located at the Dempsey E. Benton Water
Treatment Plant at 2315 Benson Road in Garner in Wake County. Water and wastewater treatment
consists of:
• Ozonation
• Coagulation and settling (Super Pulsator)
• Two (2) stage filtration [GAC/Bio filters and Final filters]
• UV disinfection
• One (1) MGD filter backwash storage tank
• Dual parallel Dissolved Air Flotation (DAF) clarifiers
• UV disinfection
• Dechlorination by calcium thiosulfate
• Chemical usage consists of:
o Ozone
o Potassium permanganate
o Ferric sulfate
o Sodium hydroxide
o PAC
o Polymer
o Chlorine
o Fluoride
o Corrosion control
o Ammonia nitrogen
o Calcium thiosulfate
o Sodium hypochlorite
o Sodium silicate
2. Discharge from said treatment works at the location specified on the attached map into Lake
Benson [Stream Segment: 27-43-(5.5)], a waterbody currently classified WS-III; NSW; CA in
subbasin 03-04-02 [HUC: 030202011002] in the Neuse River Basin.
Page 2 of 8

NPDES Permit NC0088285
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 .03021
During the period beginning upon the effective date of the 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 code
LIMITS
MONITORING REQUIREMENTS
Monthly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type
Sample
Location
Flow MGD 50050
Continuous
Recordin
Effluent
Total Suspended Solids CO530
30.0 m L
45.0 mgtL
Weekly
Grab
Effluent
pH 00400
> 6.0 and <9.0 standard
—
units
Weekly
Grab
Effluent
Total Residual Chlorine' 50060
1 17
Weekly
Grab
Effluent
Total Coliforms #/100m1 31501
Monitor & Report
Weekly
Grab
Effluent
Turbidity T 00070
Monitor & Report
2/Month
Grab
Effluent
Total Aluminum 01105
Monitor & Report
Quarterly
Grab
Effluent
Total Copper 01042
Monitor & Report
Quarterly
Grab
Effluent
Total Fluoride 00951
Monitor & Report
Quarterly
Grab
Effluent
Total Manganese 01055
Monitor & Report
Quarterly
Grab
Effluent
Total Zinc 01092
Monitor & Report
Quarterly
Grab
Effluent
Ammonia Nitrogen m L CO610
Monitor & Report
Quarterly
Grab
Effluent
Total Phosphorus m CO665
Monitor & Report
Monthly
Grab
Effluent
Total Nitrogen m ' CO600
Monitor & Report
Monthly
Grab
Effluent
Total Kjeldahl Nitrogen 00625
m L
Monitor & Report
Monthly
Grab
Effluent
NO3-N + NO2-N m 00630
Monitor & Report
Monthly
Grab
Effluent
Hardness -Total as 00900
CaCO3 m ° m
Monitor & Report
p
Quarterly
Q y
Grab
Effluent
Hardness -Total as 00900
CaCO3 m s (m
Monitor & Report
p
Quarterly
Q y
Grab
Upstream
P
Whole Effluent Toxicitye TGE6C
Pass/Fail Limit
Quarterly
Grab
Effluent
Footnotes:
1. The permittee shall submit discharge monitoring reports electronically using the NC DWR's eDMR
application system [see Section A. (3)].
2. 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.
3. TN is Total Nitrogen = TKN + NO3-N + NO2-N, where TKN is Total Kjeldahl Nitrogen, NO3-N
and NO2-N are Nitrate and Nitrite Nitrogen respectively.
4. Effluent hardness sampling should be performed in conjunction with testing for hardness dependent
metals (copper and zinc).
Page 3 of 8

NPDES Permit NC0088285
5. The Permittee shall sample instream hardness, upstream of the facility's discharge. The sample
shall be representative of the hardness in the receiving stream. See the attached outfall map for
approved sampling location. 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 permit renewal
application package. If Coalition membership is cancelled or the 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.
6. Acute toxicity limit P/F at 90% using Fathead Minnow (Pimephales promelas) during the
months of January, April, July, and October [see Section A. (2)].
There shall be no discharge of floating solids or visible foam in other than trace amounts.
Page 4 of 8

NPDES Permit NCO088285
A. (2) ACUTE TOXICITY PERMIT LIMIT (QUARTERLY)
[15A NCAC 02B .0200 et seq.] [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 Fathead Minnow (Pimephales promelas) 24-hour acute 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.
Should any single quarterly monitoring indicate a failure to meet specified limits, then monthly
monitoring will begin immediately until such time that a single test is passed. Upon passing, this
monthly test requirement will revert to quarterly in the months specified above.
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
TGE6C. 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.
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 monthlyear 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 until such time that a single test is passed. Upon passing,
this monthly test requirement will revert to quarterly in the months specified above. Assessment of
toxicity compliance is based on the toxicity testing quarter, which is the three-month time interval that
Page 5 of 8

NPDES Permit NCO088285
begins on the fast 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 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.
A. (3) ELECTRONIC REPORTING - DISCHARGE 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. Reoortine Requirements 1Suoersedes 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) intemet 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.2ov/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
1617 Mail Service Center
Page 6 of 8

NPDES Permit NC0088285
Raleigh, North Carolina 27699-1617
See "How to Request a Waiver from Electronic Reporting" section below.
Monitoring results obtained during the previous month(s) shall be summarized for each month and
reported via the eDMR system no later than the last calendar day of the month following the
completed reporting period. 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(I)(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 federalre ig ster.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.
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
Page 7 of 8

NPDES Permit NC0088285
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:
httr):Hdeci.nc.eov/about/divisions/water-resources/edmr
4. Sienatory Requirements [Supplements Section B. (11.) (b) and Supersedes Section B. (I1.)
All eDMRs submitted to the permit issuing authority shall be signed by a person described in Part 11,
Section B. (I I .xa) or by a duly authorized representative of that person as described in Part II,
Section B. (1 l.)(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. eov/about/divi sions/water-resourcestedmr
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 ISUDDlements Section D. (6.)l
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.
Page 8 of 8

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