NC0043176_Fact Sheet_20231201

Fact Sheet
NPDES Permit No. NCO043176
Permit Writer/Email Contact:Nick Coco,[e-mail]
Date: October 2,2023
Division/Branch:NC Division of Water Resources/NPDES Municipal Permitting
Fact Sheet Template: Version 09Jan2017
Permitting Action:
® Renewal
❑ Renewal with Expansion
❑ New Discharge
❑ Modification(Fact Sheet should be tailored to mod request)
Note: A complete application should include the following:
• For New Dischargers,EPA Form 2A or 2D requirements,Engineering Alternatives Analysis,Fee
• For Existing Dischargers (POTW),EPA Form 2A, 3 effluent pollutant scans,4 2nd species WET
tests.
• For Existing Dischargers (Non-POTW),EPA Form 2C with correct analytical requirements based
on industry category.
Complete applicable sections below. If not applicable, enter NA.
1. Basic Facility Information
Facility Information
Applicant/Facility Name: City of Dunn/Black River Wastewater Treatment Plant(WWTP)
Applicant Address: P.O. Box 1065,Dunn,NC 28335
Facility Address: 580 JW Edwards Lane,Dunn,NC 28334
Permitted Flow: 3.75 MGD
Facility Type/Waste: MAJOR Municipal; 100%domestic
Facility Class: Grade IV Biological Water Pollution Control System
Treatment Units: Influent pumps, equalization tank, auto bar screen, aerated grit removal,
influent flow measurement, aeration basins, clarifiers,
chlorination/dichlorination, chlorine contact chambers, effluent pumps,
effluent flow meter, cascade discharge,rotary drum thickener, aerobic
sludge digester, aerated sludge holding tank, sludge drying beds
Pretreatment Program(Y/N) N
County: Harnett
Region Fayetteville
Briefly describe the proposed permitting action and facility background: The City of Dunn applied for an
NPDES permit renewal at 3.75 MGD for the Black River WWTP on April 3,2023. This facility serves a
population of approximately 12,100 residents. Treated domestic wastewater is discharged into the Cape
Fear River, a class WS-V waterbody in the Cape Fear River Basin.
Sludge disposal: Sludge is land applied as Class B biosolids via permit WQ0006101.
Sewer Moratorium and Special Order By Consent(SOC)HistorX: On February 26, 2021,the Division
issued the City of Dunn a Statutory Sewer Moratorium letter. The City of Dunn applied for an SOC on
June 7, 2021 and was issued Environment Management Commission(EMC) SOC WQ S 17-002 on June
17,2022 to set required steps toward compliance with wastewater flow permit requirements. Under the
SOC, a schedule was set for completion of collection system and WWTP rehabilitation,with the City
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being required to achieve flow permit limit compliance by December 31, 2026. The SOC grants an initial
allocation of 0.15 MGD upon execution of the agreement and allows additional requested flow allocations
to be granted in phases as sewer and WWTP rehabilitation projects are completed. If all projects are
completed and compliance with permit conditions and limits are achieved,the moratorium shall be lifted
upon expiration of the SOC. The SOC is set to expire on March 31,2027. The City of Dunn has
communicated to the Division a desire to amend the SOC to incorporate an alternative to building out a
new force main for the Eastside Pump Station and the Division is currently working with the City on this
request.
As part of the City's efforts to treat wet weather flows and minimize Sanitary Sewer Overflows occurring
in the collection system,the City applied for and was issued an Authorization to Construct Permit
043176A05 on March 16,2023 for various plant improvements that increased the peak flow capacity of
treatment components.
Inflow and Infiltration(I/D: In their application,the City noted an estimated average daily 1/1 flow of
approximately 750,000 gpd. As previously mentioned, The City is currently under a sewer moratorium
and SOC regarding WWTP flow. In the notice of moratorium, sent 2/26/2021, it was noted that since
April 2017 the Black River WWTP had reported 6 flow limit violations and 22 Sanitary Sewer Overflows
(SSOs). The City has several projects in progress and milestones outlined in the SOC for reducing I/I and
managing wastewater flow.
2. Receiving Waterbody Information:
Receiving Waterbody Information
Outfalls/Receiving Stream(s): Outfall 001 —Cape Fear River
Stream Segment: 18-(20.7)
Stream Classification: WS-V
Drainage Area(mi2): 3,464
Summer 7Q10(cfs) 586.6
Winter 7Q10(cfs): -
30Q2 (cfs): -
Average Flow(cfs): 3,601
IWC (%effluent): 1
2022 303(d) listed/parameter: Not listed
Subject to TMDL/parameter: Yes- State wide Mercury TMDL implementation.
Basin/HUC: Cape Fear River/03030004
USGS Topo Quad: F24SW
3. Effluent Data Summary
Effluent data for Outfall 001 is summarized below for the period of February 2019 through June 2023.
Table 1. Effluent Data Summary Outfall 001
Parameter Units Average Max Min Permit Limit
Flow MGD 2.6 8.548 0.747 MA 3.75
BOD summer mg/1 3.3 18 <2 WA 18.0
MA 12.0
BOD winter mg/1 4.5 22 <2 WA 36.0
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MA 24.0
NH3N summer mg/l 0.6 10.8 <0.1 WA 6.0
MA 2.0
NH3N winter mg/l 0.7 11.2 <0.1 WA 12.0
MA 4.0
TSS mg/l 4.4 61.8 0.7 WA 45.0
MA 30.0
pH SU 6.5 7.6 6 6.0>pH<9.0
eomean
(geometric)
Fecal coliform 41100 ml g 2.6
>2420 < 1 WA 400
MA 200
DO mg/l 7.1 9.06 5.6 DA>5.0
Temperature ° C 21.0 29 12 Monitor&
Report
Total Residual Chlorine µg/l 20.1 28 20 DM 28
NO2+NO3 mg/l 4.0 16.16 <0.1 Monitor&
Report
TKN mg/l 1.9 7.59 0.26 Monitor&
Report
TN mg/1 _., 18 1.64 Monitor&
Report
TP mg/l ' ' 4.05 0.12 Monitor&
Report
Bis (2-Ethylhexyl)phthalate µg/l < 5 <20 <2 Monitor&
Report
MA-Monthly Average,WA-Weekly Average,DM-Daily Maximum,DA=Daily Average
4. Instream Data Summary
Instream monitoring may be required in certain situations, for example: 1)to verify model predictions
when model results for instream DO are within I mg/l of instream standard at full permitted flow;2)to
verify model predictions for outfall diffuser; 3)to provide data for future TMDL;4)based on other
instream concerns. Instream monitoring may be conducted by the Permittee, and there are also
Monitoring Coalitions established in several basins that conduct instream sampling for the Permittee(in
which case instream monitoring is waived in the permit as long as coalition membership is maintained).
Is this facility a member of a Monitoring Coalition with waived instream monitoring(YIN): YES
Name of Monitoring Coalition: Middle Cape Fear Basin Association
If applicable, summarize any instream data and what instream monitoring will be proposed for this
permit action: The current permit requires instream monitoring for temperature, dissolved oxygen and
temperature upstream at NC Highway 217 and downstream approximately 1400 feet below discharge.As
the permittee is a member of the Middle Cape Fear Basin Association(MCFBA)instream monitoring
requirements are provisionally waived. The nearest upstream monitoring station is MCFBA station
B6840000, located approximately 1.5 miles upstream of the outfall. The nearest downstream monitoring
station is MCFBA station B7480000, located approximately 23 miles downstream of the outfall. Due to
the distance and number of tributaries existing between the discharge point and nearest downstream
monitoring station, downstream data were not considered during the instream review. Upstream data from
January 2019 through December 2022 have been summarized below in Table 2.
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Table 2. Downstream Monitoring Data Summary
Parameter Units Upstream B6840000
Average Max Min
Temperature ° C 21.5 30.6 6.6
DO mg/1 8.1 12.1 6.14
Fecal Coliform #/100 ml (geom 94ean) 8400 4
Conductivity µmhos/cm 135 239 57
NO2+NO3 mg/1 0.46 0.78 0.16
TKN mg/1 0.73 1.45 0.41
TP mg/1 0.09 0.275 0.02
TSS mg/1 21.8 286 2.5
Turbidity NTU 1 25.2 1 278 1 1.8 I
pH s.u. 7.1 8.2 6.5
Total Hardness mg/1 26.6 36 20
As the Black River WWTP discharges 100%domestic wastewater and comprises 1%of the receiving
stream,no changes are proposed to instream monitoring at this time. Instream monitoring requirements
continue to be waived, conditional upon participation in the MCFBA.
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): In 2018,the facility reported
1 flow limit violation resulting in enforcement. The facility reported 1 flow limit violation resulting in
enforcement in 2019. In 2020,the facility reported 5 flow limit violations resulting in enforcement. The
facility reported 3 flow limit violations resulting in enforcement in 2021. The facility is currently under a
sewer moratorium and SOCS17-002.
Summarize the compliance record with aquatic toxicity test limits and any second species test results
(past 5 years): The facility passed 18 of 18 quarterly chronic toxicity tests, as well as all 4 second species
chronic toxicity tests from March 2019 to June 2023.
Summarize the results from the most recent compliance inspection: The last facility inspection conducted
in December 2021 reported that the facility was compliant.No facility inspection has been conducted
since the SOC became active.
6. Water Quality-Based Effluent Limitations (WQBELs)
Dilution and Mixing Zones
In accordance with 15A NCAC 2B.0206,the following streamflows are used for dilution considerations
for development of WQBELs: 1Q10 streamflow(acute Aquatic Life); 7Q10 streamflow(chronic Aquatic
Life;non-carcinogen HH); 30Q2 streamflow(aesthetics); annual average flow(carcinogen,HH).
If applicable, describe any other dilution factors considered(e.g., based on CORMIX model results):NA
If applicable, describe any mixing zones established in accordance with 15,4 NCAC 2B.0204(b): NA
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Oxygen-Consuming Waste Limitations
Limitations for oxygen-consuming waste(e.g., BOD) are generally based on water quality modeling to
ensure protection of the instream dissolved oxygen(DO)water quality standard. Secondary TBEL limits
(e.g., BOD=30 mg/1 for Municipals)may be appropriate if deemed more stringent based on dilution and
model results.
Ifpermit limits are more stringent than TBELs, describe how limits were developed: The facility received
an expansion permit in 1993 from 3.0 to 3.75 MGD. BOD and ammonia limits were changed from
secondary standards to current limits to maintain consistency(BPJ)with treatment levels of other WWTP
in the region. Modeling supported swapping secondary limits (TBELs)for WQBELs.
Ammonia and Total Residual Chlorine Limitations
Limitations for ammonia are based on protection of aquatic life utilizing an ammonia chronic criterion of
1.0 mg/1(summer) and 1.8 mg/l(winter). Acute ammonia limits are derived from chronic criteria,
utilizing a multiplication factor of 3 for Municipals and a multiplication factor of 5 for Non-Municipals.
Limitations for Total Residual Chlorine(TRC) are based on the NC water quality standard for protection
of aquatic life(17 ug/1)and capped at 28 ug/1(acute impacts). Due to analytical issues, all TRC values
reported below 50 ug/l are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal: The current
permit requires limits and monitoring for TRC. The TRC limits have been reviewed in the attached WLA
for toxicity and have been found to be protective.No changes are proposed.
Limitations for ammonia are based on protection of aquatic life utilizing an ammonia chronic criterion of
1.0 mg/L(summer) and 1.8 mg/L(winter). Acute ammonia limits are derived from chronic criteria,
utilizing a multiplication factor of 3 for Municipal facilities. The ammonia limits have been reviewed in
the attached WLA for toxicity and have been found to be protective.No changes are proposed.
Reasonable Potential Analysis(RPA) for Toxicants
If applicable, conduct RPA analysis and complete information below.
The need for toxicant limits is based upon a demonstration of reasonable potential to exceed water quality
standards, a statistical evaluation that is conducted during every permit renewal utilizing the most recent
effluent data for each outfall. The RPA is conducted in accordance with 40 CFR 122.44(d) (i). The NC
RPA procedure utilizes the following: 1)95% Confidence Level/95%Probability; 2)assumption of zero
background; 3)use of%2 detection limit for"less than"values; and 4) streamflows used for dilution
consideration based on 15A NCAC 2B.0206. Effective April 6,2016,NC began implementation of
dissolved metals criteria in the RPA process in accordance with guidance titled NPDES Implementation of
Instream Dissolved Metals Standards, dated June 10,2016.
A reasonable potential analysis was conducted on effluent toxicant data collected between February 2019
and July 2023. Pollutants of concern included toxicants with positive detections and associated water
quality standards/criteria. Based on this analysis,the following permitting actions are proposed for this
permit:
• Effluent Limit with Monitoriniz. The following parameters will receive a water quality-based
effluent limit(WQBEL) since they demonstrated a reasonable potential to exceed applicable
water quality standards/criteria: None
• Monitoring Only. The following parameters will receive a monitor-only requirement since they
did not demonstrate reasonable potential to exceed applicable water quality standards/criteria,
but the maximum predicted concentration was>50%of the allowable concentration: None
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• No Limit or Monitoring: The following parameters will not receive a limit or monitoring, since
they did not demonstrate reasonable potential to exceed applicable water quality
standards/criteria and the maximum predicted concentration was<50%of the allowable
concentration:None
• POTW Effluent Pollutant Scan Review: Three effluent pollutant scans (2020,2021 and 2022)
were evaluated for additional pollutants of concern.
o The following parameter(s)will receive a water quality-based effluent limit(WQBEL)
with monitoring, since as part of a limited data set,two samples exceeded the allowable
discharge concentration: None
o The following parameter(s)will receive a monitor-only requirement, since as part of a
limited data set, one sample exceeded the allowable discharge concentration: None
o The following parameters will not receive a limit or monitoring, since they did not
demonstrate reasonable potential to exceed applicable water quality standards/criteria and
the maximum predicted concentration was<50%of the allowable concentration: Total
Arsenic, Total Beryllium, Total Cadmium, Total Chromium, Total Copper, Total
Cyanide,Total Lead, Total Nickel, Total Selenium, Total Silver, Total Zinc,Bis(2-
ethylhexyl)phthalate, Total Phenolic Compounds, Chlorodibromomethane,
Dichlorobromomethane, Chloroform
In their application, the City informed the Division that City staff had identified an inadvertent
introduction of Bis (2-ethylhexyl)phthalate into their samples via the tubing used during their collection
of samples during the previous permit cycle's priority pollutant analyses. The City has changed sampling
equipment as a result of this knowledge. Based on review of the data provided,no reasonable potential to
violate state Bis(2-ethylhexyl)phthalate water quality standards was identified and the monitoring
requirement has been removed from the permit.
As this facility discharges to WS-V waters, analysis of the parameters listed in 15A NCAC 02B .0218
was conducted.No chlorinated phenolic compound was reported as detected in the effluent pollutant
scans. Total dissolved residue was not reported at levels greater than 500 mg/L in the effluent pollutant
scans. Effluent hardness was not greater than 100 mg/L in the effluent pollutant scans. Effluent nitrate+
nitrite was reported at a level greater than 10 mg/L during one effluent pollutant scan. However, as the
discharge is 1%of the receiving stream,this does not result in an instream concentration for Nitrate of 10
mg/L and no monitoring has been added at this time for Nitrate. Toluene was detected in one effluent
pollutant scan. However, it was reported at levels well below the allowable discharge concentration and
no monitoring has been added at this time for Toluene.
If applicable, attach a spreadsheet of the RPA results as well as a copy of the Dissolved Metals
Implementation Fact Sheet for freshwater/saltwater to this Fact Sheet. Include a printout of the RPA
Dissolved to Total Metal Calculator sheet if this is a Municipality with a Pretreatment Program.
Toxicity Testing Limitations
Permit limits and monitoring requirements for Whole Effluent Toxicity(WET)have been established in
accordance with Division guidance(per WET Memo, 8/2/1999). Per WET guidance, all NPDES permits
issued to Major facilities or any facility discharging"complex"wastewater(contains anything other than
domestic waste)will contain appropriate WET limits and monitoring requirements,with several
exceptions. The State has received prior EPA approval to use an Alternative WET Test Procedure in
NPDES permits,using single concentration screening tests,with multiple dilution follow-up upon a test
failure.
Describe proposed toxicity test requirement: This is a Major POTW, and a chronic WET limit will
continue on a quarterly frequency at an effluent concentration of 1%.
Mercury Statewide TMDL Evaluation
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There is a statewide TMDL for mercury approved by EPA in 2012. The TMDL target was to comply
with EPA's mercury fish tissue criteria(0.3 mg/kg) for human health protection. The TMDL established a
wasteload allocation for point sources of 37 kg/year(81 lb/year), and is applicable to municipals and
industrial facilities with known mercury discharges. Given the small contribution of mercury from point
sources(-2%of total load),the TMDL emphasizes mercury minimization plans (MMPs)for point source
control. Municipal facilities>2 MGD and discharging quantifiable levels of mercury(>1 ng/1)will
receive an MMP requirement. Industrials are evaluated on a case-by-case basis, depending if mercury is a
pollutant of concern. Effluent limits may also be added if annual average effluent concentrations exceed
the WQBEL value(based on the NC WQS of 12 ng/1) and/or if any individual value exceeds a TBEL
value of 47 ng/l.
Table 3. Mercury Effluent Data Summary
2020 2021 2022
#of Samples 1 1 1
Annual Average Conc. n /L 3.94 5.23 1.99
Maximum Conc.,n /L 3.94 5.23 1.99
TBEL,n /L 47
WQBEL,n /L 1 1223.0
Describe proposed permit actions based on mercury evaluation: Since no annual average mercury
concentration exceeded the WQBEL, and no individual mercury sample exceeded the TBEL at any flow
tier,no mercury limit is required. However, since the facility is>2 MGD and reported quantifiable levels
of mercury(> 1 ng/1), a mercury minimization plan(MMP)has been added to the permit.
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation
within this permit: NA
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: As required by Session
Law 2018-5, Senate Bill 99, Section 13.1(r), every applicant shall submit documentation of any additional
pollutants for which there are certified methods with the permit application if their discharge is
anticipated via a Chemical Addendum to NPDES Application table. The City of Dunn informed the
Division that no monitoring for additional pollutants has been conducted(see attached chemical
addendum) and therefore no additional pollutants of concern have been identified.
If applicable, describe any special actions (HQW or ORW) this receiving stream and classification shall
comply with in order to protect the designated waterbody:NA
If applicable, describe any compliance schedules proposed for this permit renewal in accordance with
1 SA NCAC 2H.0107(c)(2)(B), 40CFR 122.47, and EPA May 2007 Memo: NA
If applicable, describe any water quality standards variances proposed in accordance with NCGS 143-
215.3(e) and 15A NCAC 2B.0226 for this permit renewal:NA
7. Technology-Based Effluent Limitations (TBELs)
Municipals (if not applicable,delete and skip to Industrials)
Are concentration limits in the permit at least as stringent as secondary treatment requirements (30 mg/1
BODS/TSS for Monthly Average, and 45 mg/l for BODS/TSS for Weekly Average). YES
If NO,provide a justification for alternative limitations (e.g., waste stabilization pond). NA
Are 85%removal requirements for BOD51TSS included in the permit? YES
If NO,provide a justification (e.g., waste stabilization pond). NA
8. Antidegradation Review (New/Expanding Discharge):
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The objective of an antidegradation review is to ensure that a new or increased pollutant loading will not
degrade water quality. Permitting actions for new or expanding discharges require an antidegradation
review in accordance with 15A NCAC 2B.0201. Each applicant for a new/expanding NPDES permit
must document an effort to consider non-discharge alternatives per 15A NCAC 211.0105(c)(2). In all
cases, existing instream water uses and the level of water quality necessary to protect the existing use is
maintained and protected.
If applicable, describe the results of the antidegradation review, including the Engineering Alternatives
Analysis (EAA) and any water quality modeling results:NA
9. Antibacksliding Review:
Sections 402(o)(2) and 303(d)(4)of the CWA and federal regulations at 40 CFR 122.44(1)prohibit
backsliding of effluent limitations in NPDES permits. These provisions require effluent limitations in a
reissued permit to be as stringent as those in the previous permit,with some exceptions where limitations
may be relaxed(e.g.,based on new information,increases in production may warrant less stringent TBEL
limits, or WQBELs may be less stringent based on updated RPA or dilution).
Are any effluent limitations less stringent than previous permit(YES/NO): NO; however,based on the
reasonable potential analysis(RPA) showing no reasonable potential to violate state water quality
standards,the monitoring requirement for bis(2-ethylhexyl)phthalate has been removed from the permit.
If YES, confirm that antibacksliding provisions are not violated:N/A
10. Monitoring Requirements
Monitoring frequencies for NPDES permitting are established in accordance with the following
regulations and guidance: 1) State Regulation for Surface Water Monitoring, 15A NCAC 2B.0500;2)
NPDES Guidance,Monitoring Frequency for Toxic Substances (7/15/2010 Memo); 3)NPDES Guidance,
Reduced Monitoring Frequencies for Facilities with Superior Compliance(10/22/2012 Memo); 4)Best
Professional Judgement(BPJ). Per US EPA(Interim Guidance, 1996),monitoring requirements are not
considered effluent limitations under Section 402(o) of the Clean Water Act, and therefore anti-
backsliding prohibitions would not be triggered by reductions in monitoring frequencies.
For instream monitoring,refer to Section 4.
The Division required additional nutrient monitoring at the Black River WWTP via a letter on January 10,
2019. As a result,monitoring for TKN,NO2+NO3, and TN was increased from monthly to weekly for
the duration of April 1,2019 through December 31,2020. This additional monitoring was incorporated as
a footnote in the existing permit during the renewal. The City conducted the increased monitoring and
reported the results in their monitoring reports. As the deadline for the additional monitoring has past, the
footnote has been removed from the permit.
As the City discharges 100%domestic wastewater, conductivity monitoring is not required.
The City of Dunn has requested continuation of 2/week monitoring for BOD based on 2012 DWR
Guidance Regarding the Reduction of Monitoring Frequencies in NPDES Permits for Exceptionally
Performing Facilities. The City does not wish to pursue reduction in monitoring frequency for ammonia,
TSS and fecal coliform to 2/week at this time. The last three years of the facility's data for these
parameters have been reviewed in accordance with the criteria outlined in the guidance. Based on this
review, 2/week monitoring frequency has been maintained for BOD.
The existing permit does not require monitoring for total hardness in the facility effluent or upstream of
the facility. While the facility discharges to WS waters(NC Standard— 100 mg/L), and is subject to
standards for hardness-dependent metals,due to:
• the Black River WWTP discharging 100%domestic wastewater,
• the discharge comprising 1%of the receiving stream,
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• The City providing effluent hardness data as part of the effluent pollutant scans and
• the MCFBA conducting monitoring for total hardness upstream of the discharge,
no changes are proposed to hardness monitoring at this time.
As the facility discharges to WS-V waters, and since a finalized EPA method for sampling and analyzing
PFAS in wastewater is not currently available, effluent PFAS monitoring has been added to the permit at
a quarterly frequency using the Draft Method 1633. Upon evaluation of laboratory availability and
capability to perform the draft analytical method, it was determined that the sampling may be conducted
using the 3rd draft method 1633 or more recent. Sampling using the draft method shall take effect the first
full calendar quarter following 6 months after the effective date of the permit to provide the City time to
select a laboratory, develop a contract, and begin collecting samples. Effective 6 months after EPA has a
final wastewater method in 40 CFR136 published in the Federal Register,the City shall conduct effluent
monitoring using the Final Method 1633 and is no longer required to conduct influent and post-filtration
monitoring.
11. Electronic Reporting Requirements
The US EPA NPDES Electronic Reporting Rule was finalized on December 21, 2015. Effective
December 21, 2016,NPDES regulated facilities are required to submit Discharge Monitoring Reports
(DMRs) electronically. While NPDES regulated facilities would initially be required to submit additional
NPDES reports electronically effective December 21, 2020, EPA extended this deadline from December
21,2020,to December 21,2025. The current compliance date, effective January 4,2021,was extended as
a final regulation change published in the November 2, 2020 Federal Register. This permit contains the
requirements for electronic reporting, consistent with Federal requirements.
12. Summary of Proposed Permitting Actions:
Table 4. Current Permit Conditions and Proposed Changes Outfall 001
Parameter Current Permit Proposed Change Basis for Condition/Change
Flow MA 3.75 MGD No change 15A NCAC 2B .0505
BOD5 Summer: No change WQBEL. 1993 BPJ; 2012 DWR
MA 12.0 mg/l Guidance Regarding the Reduction of
WA 18.0 mg/l Monitoring Frequencies in NPDES
Winter: Permits for Exceptionally Performing
MA 24.0 mg/1 Facilities
WA 36.0 mg/l
Monitor and report
2/week
NH3-N Summer: No change WQBEL. 2023 WLA; Surface Water
MA 2.0 mg/l Monitoring, 15A NCAC 2B. 0500
WA 6.0 mg/l
Winter:
MA 4.0 mg/l
WA 12.0 mg/l
Monitor and report Dail
TSS MA 30 mg/l No change TBEL. Secondary treatment
WA 45 mg/l standards/40 CFR 133 / 15A NCAC 2B
Monitor and report Daily .0406; Surface Water Monitoring, 15A
NCAC 2B. 0500
Fecal Both flow tiers: No change WQBEL. State WQ standard, 15A
coliform MA 200/100ml NCAC 2B .0200; Surface Water
WA 400/100m1 Monitoring, 15A NCAC 2B. 0500
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Monitor and report Daily
Temperature Monitor and Report Daily No change Surface Water Monitoring, 15A NCAC
2B. 0508
DO >5 mg/1 No change WQBEL. State WQ standard, 15A
Monitor and Report Daily NCAC 2B .0200; 15A NCAC 02B
.0500
pH 6—9 SU No change WQBEL. State WQ standard, 15A
Monitor and Report Daily NCAC 2B .0200; 15A NCAC 02B
.0500
Total DM 28 ug/L No change WQBEL. 2023 WLA. Surface Water
Residual Monitor and Report Daily Monitoring, 15A NCAC 2B. 0500
Chlorine
TKN Monitor and Report No change For calculation of TN
Monthly
NO2+NO3 Monitor and Report No change For calculation of TN
Monthly tim
Total Monitor and Report No change Surface Water Monitoring, 15A NCAC
Nitrogen Monthly 2B. 0500
Total Monitor and Report No change Surface Water Monitoring, 15A NCAC
Phosphorus Monthly 2B. 0500
Bis (2- Monitor and Report Remove requirements Based on results of RPA;No RP,
ethylhexyl) Quarterly Predicted Max<50%of Allowable Cw
phthalate Special Condition A.(6.) -No Monitoring required
—monitoring and limits
reo ener
See Special Evaluation of PFAS contribution:
PFAS No requirement Condition A.(5.) discharging into WS waters; o
PFAS Monitoring Investigation of PFAS from 100/o
Re uirements domestic waste
Toxicity Test Chronic limit, 1% No change WQBEL. No toxics in toxic amounts.
effluent 15A NCAC 213.0200 and 15A NCAC
213.0500
Effluent Three times per permit No change; 40 CFR 122
Pollutant cycle conducted in 2025,
Scan 2026,2027
Instream Monitor and Report for No change Surface Water Monitoring, 15A NCAC
Monitoring temperature and 2B. 0508; Instream monitoring review
dissolved oxygen 3/week
during June through
September and 1/week
during remainder of the
year;MCFBA waiver
Mercury MMP Special Condition No change; maintain Consistent with 2012 Statewide
Minimization MMP Mercury TMDL Implementation—
Plan(MMP) multiple detections during review
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Nutrient Special Condition A.(5.) Remove condition Division may require additional nutrient
Monitoring Cape Fear River Basin monitoring without reopener condition
Reopener Nutrient Monitoring
Reopener
Electronic Electronic Reporting No change In accordance with EPA Electronic
Reporting I Special Condition I Reporting Rule 2015.
MGD—Million gallons per day,MA- Monthly Average,WA—Weekly Average,DM—Daily Max
13. Public Notice Schedule:
Permit to Public Notice: xx/xx/xxxx
Per 15A NCAC 2H .0109 & .0111, The Division will receive comments for a period of 30 days following
the publication date of the public notice.Any request for a public hearing shall be submitted to the
Director within the 30 days comment period indicating the interest of the party filing such request and the
reasons why a hearing is warranted.
14. NPDES Division Contact
If you have any questions regarding any of the above information or on the attached permit,please
contact Nick Coco at(919) 707-3609 or via email at nick.cocoAdeq.nc..ov.
15. Fact Sheet Addendum (if applicable):
Were there any changes made since the Draft Permit was public noticed(Yes/No):NO
If Yes, list changes and their basis below:NA
16. Fact Sheet Attachments (if applicable):
• RPA Spreadsheet Summary
• NPDES Implementation of Instream Dissolved Metals Standards—Freshwater Standards
• NH3/TRC WLA Calculations
• BOD&TSS Removal Rate Calculations
• Mercury TMDL Calculations
• Monitoring Frequency Reduction Request and Evaluation
• Additional information Requested
• WET Testing and Self-Monitoring Summary
Page 11 of 11

Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM DATA POINTS = 58
REQUIRED DATA ENTRY CHECK WQS
Table 1. Project Information Table 2. Parameters of Concern
❑ CHECK IF HQW OR ORW WQS Name WQs Type Chronic Modifier Acute PQL Units
Facility Name Black River WWTP Par01 Arsenic Aquactic Life C 150 FW 340 ug/L
WWTP/WTP Class IV Par02 Arsenic Human Health C 10 HH/WS N/A ug/L
Water Supply
NPDES Permit NCO043176 Par03 Beryllium Aquatic Life NC 6.5 FW 65 ug/L
Outfall 001 Par04 Cadmium Aquatic Life NC 0.6189 FW 3.4265 ug/L
Flow, Qw (MGD) 3.750 Par05 Chlorides Aquatic Life NC 230 FW mg/L
Receiving Stream Cape Fear River Par06 Chlorinated Phenolic Compounds Water Supply NC 1 A ug/L
HUC Number 03030004 Par07 Total Phenolic Compounds Aquatic Life NC 300 A ug/L
Stream Class W S-V Par08 Chromium III Aquatic Life NC 124.0152 FW 953.9571 ug/L
❑✓ Apply WS Hardness WQC Par09 Chromium VI Aquatic Life NC 11 FW 16 pg/L
7Q10s (cfs) 586.600 Par10 Chromium, Total Aquatic Life NC N/A FW N/A pg/L
7Q10w (cfs) 586.60 Par11 Copper Aquatic Life NC 8.3199 FW 11.1252 ug/L
30Q2 (cfs) 586.60 Par12 Cyanide Aquatic Life NC 5 FW 22 10 ug/L
QA(cfs) 3601.00 Par13 Fluoride Aquatic Life NC 1,800 FW ug/L
1Q10s (cfs) 472.92 Par14 Lead Aquatic Life NC 3.1595 FW 81.1453 ug/L
Effluent Hardness 35 mg/L (Avg) Par15 Mercury Aquatic Life NC 12 FW 0.5 ng/L
------------- ----------------------
Upstream Hardness 26.56 mg/L (Avg) Par16 Molybdenum Water Supply NC 160 WS ug/L
------------- ----------------------
Combined Hardness Chronic 26.64 mg/L Par17 Nickel Aquatic Life NC 39.2854 FW 353.9234 pg/L
Combined Hardness Acute 26.66 mg/L -I Par18 Nickel Water Supply NC 25.0000 WS N/A pg/L
Data Source(s) EPA Nationally Recommended Water Quality Par19 Selenium Aquatic Life NC 5 FW 56 ug/L
❑ CHECK TO APPLY MODEL Criteria used for Bis (2-ethylhexyl) phthalate, Par20 Silver Aquatic Life NC 0.06 FW 0.3310 ug/L
chlorodibromomethane and chloroform assessment.
North Carolina Instream Target Value used for Par21 Zinc Aquatic Life NC 133.7365 FW 132.7344 ug/L
Dichlorobromomethane assessment. Par22 Bis (2-ethylhexyl) phthalate Water Supply C 0.32 WS pg/L
Par23 Chlorodibromomethane Water Supply C 0.8 WS pg/L
Par24 Dichlorobromomethane Water Supply C 0.55 WS pg/L
43176 RPA, input
10/25/2023

REASONABLE POTENTIAL ANALYSIS
H1 H2 Use"PASTE SPECIAL Use"PASTE SPECIAL
Effluent Hardness Values"then"COPY" Upstream Hardness Values"then"COPY"
Maximum data .Maximum data
points=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 12/8/2020 23 23 Std Dev. 11.5326 1 1/10/2019 20 20 Std Dev. 4.8413
2 9/13/2021 46 46 Mean 35.0000 2 4/11/2019 20 20 Mean 26.5556
3 6/6/2022 36 36 C.V. (default) 0.6000 3 7/9/2019 24 24 C.V. 0.1823
4 n 3 4 10/3/2019 36 36 n 18
5 10th Per value 25.60 mg/L 5 1/29/2020 28 28 10th Per value 20.00 mg/L
6 Average Value 35.00 mg/L 6 4/9/2020 24 24 Average Value 26.56 mg/L
7 Max. Value 46.00 mg/L 7 5/7/2020 28 28 Max. Value 36.00 mg/L
8 8 6/18/2020 24 24
9 9 7/17/2020 24 24
10 10 10/29/2020 28 28
11 11 1/4/2021 20 20
12 12 3/29/2021 32 32
13 13 4/15/2021 28 28
14 14 7/6/2021 28 28
15 15 10/14/2021 24 24
16 16 4/13/2022 24 24
17 17 7/22/2022 30 30
18 18 10/13/2022 36 36
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
58 58
43176 RPA, data
- 1 - 10/25/2023

REASONABLE POTENTIAL ANALYSIS
Par01 & Par02
Use"PASTE SPECIAL
Arsenic Values"then"COPY"
Maximum data
points=58
Date Data BDL=1/2DL Results
1 12/8/2020 < 10 5 Std Dev. 0.0000
2 9/13/2021 < 10 5 Mean 5.0000
3 6/6/2022 < 10 5 C.V. (default) 0.6000
4 n 3
5
6 Mult Factor= 3.00
7 Max. Value 5.0 ug/L
8 Max. Pred Cw 15.0 ug/L
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
43176 RPA, data
-2 - 10/25/2023

REASONABLE POTENTIAL ANALYSIS
Par03 Par04
Use"PASTE SPECIAL Use"PASTE SPECIAL
Beryllium Values"then"COPY" Cadmium Values"then"COPY"
Maximum data .Maximum data
points=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 12/8/2020 < 1 0.5 Std Dev. 0.0000 1 12/8/2020 < 1 0.5 Std Dev. 0.0000
2 9/13/2021 < 1 0.5 Mean 0.5000 2 9/13/2021 < 1 0.5 Mean 0.5000
3 6/6/2022 < 1 0.5 C.V. (default) 0.6000 3 6/6/2022 < 1 0.5 C.V. (default) 0.6000
4 n 3 4 n 3
5 5
6 Mult Factor= 3.00 6 Mult Factor= 3.00
7 Max. Value 0.50 ug/L 7 Max. Value 0.500 ug/L
8 Max. Pred Cw 1.50 ug/L 8 Max. Pred Cw 1.500 ug/L
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
58 58
43176 RPA, data
-3- 10/25/2023

REASONABLE POTENTIAL ANALYSIS
Par07 Part O
Use"PASTE SPECIAL- Use"PASTE SPECIAL
Total Phenolic Compounds
Values"then"COPY". Values"then"COPY"
Maximum data points Chromium, Total .Maximum data
=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 12/8/2020 < 5 2.5 Std Dev. 0.0000 1 12/8/2020 < 5 2.5 Std Dev. 0.0000
2 9/13/2021 < 5 2.5 Mean 2.5000 2 9/13/2021 < 5 2.5 Mean 2.5000
3 6/6/2022 < 5 2.5 C.V. (default) 0.6000 3 6/6/2022 < 5 2.5 C.V. (default) 0.6000
4 n 3 4 n 3
5 5
6 Mult Factor= 3.00 6 Mult Factor= 3.00
7 Max. Value 2.5 ug/L 7 Max. Value 2.5 pg/L
8 Max. Pred Cw 7.5 ug/L 8 Max. Pred Cw 7.5 pg/L
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
58 58
43176 RPA, data
-4- 10/25/2023

REASONABLE POTENTIAL ANALYSIS
Pal Par12
Use"PASTE SPECIAL Use"PASTE SPECIAL
Copper Values"then"COPY" Cyanide Values"then"COPY"
pp .Maximum data y .Maximum data
points=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 12/8/2020 3 3 Std Dev. 2.0817 1 12/8/2020 < 5 5 Std Dev. 0.0000
2 9/13/2021 7 7 Mean 5.3333 2 9/13/2021 < 5 5 Mean 5.00
3 6/6/2022 6 6 C.V. (default) 0.6000 3 6/6/2022 < 5 5 C.V. (default) 0.6000
4 n 3 4 n 3
5 5
6 Mult Factor= 3.00 6 Mult Factor= 3.00
7 Max. Value 7.00 ug/L 7 Max. Value 5.0 ug/L
8 Max. Pred Cw 21.00 ug/L 8 Max. Pred Cw 15.0 ug/L
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
58 58
43176 RPA, data
- 5- 10/25/2023

REASONABLE POTENTIAL ANALYSIS
Par14 Use"PASTE SPECIAL Par17 & Par18 use"PASTE
Values"then"COPY" SPECIAL-Values"
Lead Maximum data Nickel then"COPY".
.
points=58 Maximum data
Date BDL=1/2DL Results Date Data BDL=1/2DL Results points=58
1 12/8/2020 < 5 2.5 Std Dev. 0.0000 1 12/8/2020 < 10 5 Std Dev. 8.6603
2 9/13/2021 < 5 2.5 Mean 2.5000 2 9/13/2021 < 10 5 Mean 10.0000
3 6/6/2022 < 5 2.5 C.V. (default) 0.6000 3 6/6/2022 20 20 C.V. (default) 0.6000
4 n 3 4 n 3
5 5
6 Mult Factor= 3.00 6 Mult Factor= 3.00
7 Max. Value 2.500 ug/L 7 Max. Value 20.0 pg/L
8 Max. Pred Cw 7.500 ug/L 8 Max. Pred Cw 60.0 pg/L
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
58 58
43176 RPA, data
-6- 10/25/2023

REASONABLE POTENTIAL ANALYSIS
Par19 Par20
Use"PASTE SPECIAL- Use"PASTE SPECIAL
Values"then"COPY". Values"then"COPY"
Selenium Maximum data points Silver .Maximum data
=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 12/8/2020 < 10 5 Std Dev. 0.0000 1 12/8/2020 < 5 2.5 Std Dev. 0.0000
2 9/13/2021 < 10 5 Mean 5.0000 2 9/13/2021 < 5 2.5 Mean 2.5000
3 6/6/2022 < 10 5 C.V. (default) 0.6000 3 6/6/2022 < 5 2.5 C.V. (default) 0.6000
4 n 3 4 n 3
5 5
6 Mult Factor= 3.00 6 Mult Factor= 3.00
7 Max. Value 5.0 ug/L 7 Max. Value 2.500 ug/L
8 Max. Pred Cw 15.0 ug/L 8 Max. Pred Cw 7.500 ug/L
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
58 58
43176 RPA, data
- 7- 10/25/2023

REASONABLE POTENTIAL ANALYSIS
Par21 Par22 use"PASTE
Use"PASTE SPECIAL
Values"then"COPY" SPECIAL-Values"
Zinc Maximum data Bis (2-ethylhexyl) phthalate then"COPY".
.
points=58 Maximum data
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results points=58
1 12/8/2020 38 38 Std Dev. 15.3948 1 4/10/2019 < 20 10 Std Dev. 3.3957
2 9/13/2021 59 59 Mean 55.0000 2 7/10/2019 < 20 10 Mean 2.6216
3 6/6/2022 68 68 C.V. (default) 0.6000 3 10/7/2019 < 20 10 C.V. 1.2953
4 n 3 4 1/15/2020 < 2 1 n 19
5 5 4/15/2020 < 2 1
6 Mult Factor= 3.00 6 7/27/2020 < 2 1 Mult Factor= 1.80
7 Max. Value 68.0 ug/L 7 10/12/2020 < 2 1 Max. Value 10.0 pg/L
8 Max. Pred Cw 204.0 ug/L 8 1/13/2021 < 2 1 Max. Pred Cw 18.0 pg/L
9 9 4/12/2021 < 2 1
10 10 7/5/2021 < 2 1
11 11 10/11/2021 < 2 1
12 12 1/24/2022 < 2 1
13 13 6/5/2022 4.81 4.81
14 14 9/7/2022 < 2 1
15 15 12/12/2022 < 2 1
16 16 1/9/2023 < 2 1
17 17 4/17/2023 < 2 1
18 18 5/17/2023 < 2 1
19 19 7/5/2023 < 2 1
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
58 58
43176 RPA, data
-8- 10/25/2023

REASONABLE POTENTIAL ANALYSIS
Par23 Par24
Use"PASTE SPECIAL Use"PASTE SPECIAL
Chlorodibromomethane Values"then"COPY" Dichlorobromomethane Values"then"COPY"
Maximum data .Maximum data
points=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 12/8/2020 < 2 1 Std Dev. 0.3291 1 12/8/2020 < 2 1 Std Dev. 2.0785
2 9/13/2021 < 2 1 Mean 1.2 2 9/13/2021 < 2 1 Mean 2.2000
3 6/6/2022 1.57 1.57 C.V. (default) 0.6 3 6/6/2022 4.6 4.6 C.V. (default) 0.6000
4 n 3 4 n 3
5 5
6 Mult Factor= 3.00 6 Mult Factor= 3.00
7 Max. Value 2 pg/L 7 Max. Value 4.600000 pg/L
8 Max. Pred Cw 5 pg/L 8 Max. Pred Cw 13.800000 pg/L
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
58 58
43176 RPA, data
-9- 10/25/2023

REASONABLE POTENTIAL ANALYSIS
Par25
Use"PASTE SPECIAL
Chloroform values"then"COPY"
Maximum data
points=58
Date Data BDL=1/2DL Results
1 12/8/2020 5 5 Std Dev. 1.2644
2 9/13/2021 5 5 Mean 5.7300
3 6/6/2022 7.19 7.19 C.V. (default) 0.6000
4 n 3
5
6 Mult Factor= 3.00
7 Max. Value 7.190000 tag/L
8 Max. Pred Cw 21.570000 tag/L
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
43176 RPA, data
- 10 - 10/25/2023

Black River WWTP > Outfall 001
NCO043176 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators QW = 3.75 MGD
MAXIMUM DATA POINTS = 58
Qw (MGD) = 3.7500 WWTP/WTP Class: IV COMBINED HARDNESS (mg/L)
1Q10S (cfs) = 472.92 IWC% @ 1Q10S = 1.214143598 Acute =26.66 mg/L
7Q10S (cfs) = 586.60 IWC% @ 7Q10S = 0.981157555 Chronic =26.64 mg/L
7Q10W (cfs) = 586.60 IWC% @ 7Q10W= 0.981157555 YOU HAVE DESIGNATED THIS RECEIVING
30Q2 (cfs) = 586.60 IWC% @ 30Q2 = 0.981157555 STREAM AS WATER SUPPLY
Avg. Stream Flow, QA(cfs) = 3601.00 IW%C @ QA= 0.161153373 Effluent Hard: 0 value > 100 mg/L
Receiving Stream: Cape Fear River HUC 03030004 Stream Class: WS-V Effluent Hard Avg = 35 mg/L
PARAMETER NC STANDARDS OR EPA CRITERIA J CO) REASONABLE POTENTIAL RESULTS RECOMMENDED ACTION
TYPE Chronic Standard Acute a. D n #Det. Max Pred Cw Allowable Cw
Acute (FW): 28,003.3
Arsenic C 150 FW(7Q10s) 340 ug/L
3 0 15.0 Chronic (FW): 15,288.1
C.V. (default) Max MDL_= 10
Arsenic C 10 HH/WS(Qavg) ug/L Note: n<9 NO DETECTS Chronic (HH): 6,205.3 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set Max MDL 10 Monitoring required
Acute: 5,353.57
Beryllium NC 6.5 FW(7Q10s) 65 ug/L 3 0 1.50
Note: n<9 C.V. (default) Chronic: 662.48 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 1 Monitoring required
Acute: 282.214
Cadmium NC 0.6189 FW(7Q10s) 3.4265 ug/L 3 0 1.500
Note: n<9 C.V. (default) I Chronic: 63.078 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 1 Monitoring required
Acute: NO WQS
Total Phenolic Compounds NC 300 A(30Q2) ug/L 3 0 7.5 _
Note: n<9 C.V. (default) Chronic 30,576.1 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 5 Monitoring required
Acute: 78,570.4
Chromium III NC 124.02 FW(7Q10s) 953.96 µg/L 0 0 N/A
Chronic: 12,639.7
Acute: 1,317.8
Chromium VI NC 11 FW(7Q10s) 16 µg/L 0 0 N/A
Chronic: 1,121.1
Chromium, Total NC ua/L 3 0 7.5 Max reported value=2.5 a: No monitoring required if all Total Chromium
Note: n<9 C.V. (default) samples are < 5 pg/L or Pred. max for Total Cr is <
Limited data set NO DETECTS Max MDL= 5 allowable Cw for Cr VI.
Acute: 916.30
Copper NC 8.3199 FW(7010s) 11.1252 ua/L 3 3 21.00
Note: n<9 C.V. (default) Chronic: 847.97 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set No value>Allowable Cw Monitoring required
Acute: 1,812.0
Cyanide NC 5 FW(7010s) 22 10 u2/L 3 0 15.0
Note: n<9 C.V. (default) Chronic_ 509.6
No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 10 Monitoring required
43176 RPA, rpa
Page 1 of 2 10/25/2023

Black River WWTP > Outfall 001
NCO043176 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 3.75 MGD
Acute: 6,683.339
Lead NC 3.1595 FW(7Q10s) 81.1453 ug/L 3 0 7.500 _
Note: n<9 C.V. (default) Chronic 322.017 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 5 Monitoring required
Acute (FW): 29,150.0
Nickel NC 39.2854 FW(7Q10s) 353.9234 µg/L
3 1 60.0 [Chronic (FW): 4,004.0
Note: n<9 C.V. (default) No value>Allowable Cw
Nickel NC 25.0000 WS(7Q10s) µg/L Limited data set Chronic (WS): 2,548.0 No RP, Predicted Max< 50% of Allowable Cw- No
No value>Allowable Cw Monitoring required
Acute: 4,612.3
Selenium NC 5 FW(7Q10s) 56 ug/L 3 0 15.0 _
Note: n<9 C.V. (default) Chronic 509.6 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 10 Monitoring required
Acute: 27.263
Silver NC 0.06 FW(7Q10s) 0.3310 ug/L 3 0 7.500
Note: n<9 C.V. (default) Chronic: 6.115 All values non-detect< 5 ug/L; No monitoring required
Limited data set NO DETECTS Max MDL= 5
Acute: 10,932.3 No RP, Predicted Max< 50% of Allowable Cw- No
Zinc NC 133.7365 FW(7Q10s) 132.7344 ug/L 3 3 204.0 Monitoring required
Note: n<9 C.V. (default) Chronic: 13,630.5
Limited data set No value>Allowable Cw
Acute: NO WQS
Bis (2-ethylhexyl) phthalate C 0.32 WS(Qavg) µg/L 19 1 18.00000
Chronic: 198.569 No RP, Predicted Max< 50% of Allowable Cw- No
No value >Allowable Cw Monitoring required
-----------------------------
Acute: NO WQS
Chlorodibromomethane C 0.8 WS(Qavg) µg/L 3 1 4.71000
Note: n<9 C.V. (default) Chronic: 496.42151 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set No value > Allowable Cw Monitoring required
Acute: NO WQS
Dichlorobromomethane C 0.55 WS(Qavg) µg/L 3 1 13.80000 _
Note: n<9 C.V. (default) Chronic 341.28978 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set No value > Allowable Cw Monitoring required
Acute: NO WQS
Chloroform C 60 WS(Qavg) µg/L 3 3 21.57000
Note: n<9 C.V. (default) Chronic: 37231.61290 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set No value > Allowable Cw Monitoring required
43176 RPA, rpa
Page 2 of 2 10/25/2023

Permit No. NCO043176
NPDES Implementation of Instream Dissolved Metals Standards-Freshwater Standards
The NC 2007-2015 Water Quality Standard(WQS)Triennial Review was approved by the NC
Environmental Management Commission(EMC)on November 13,2014. The US EPA subsequently
approved the WQS revisions on April 6,2016,with some exceptions. Therefore,metal limits in draft
permits out to public notice after April 6,2016 must be calculated to protect the new standards - as
approved.
Table 1.NC Dissolved Metals Water Q ality Standards/A uatic Life Protection
Parameter Acute FW, µg/l Chronic FW, µg/l Acute SW, µg/1 Chronic SW, µg/1
(Dissolved) (Dissolved) (Dissolved) (Dissolved)
Arsenic 340 150 69 36
Beryllium 65 6.5 --- ---
Cadmium Calculation Calculation 40 8.8
Chromium III Calculation Calculation --- ---
Chromium VI 16 11 1100 50
Copper Calculation Calculation 4.8 3.1
Lead Calculation Calculation 210 8.1
Nickel Calculation Calculation 74 8.2
Silver Calculation 0.06 1.9 0.1
Zinc Calculation Calculation 90 81
Table 1 Notes:
1. FW=Freshwater, SW= Saltwater
2. Calculation=Hardness dependent standard
3. Only the aquatic life standards listed above are expressed in dissolved form. Aquatic life
standards for Mercury and selenium are still expressed as Total Recoverable Metals due to
bioaccumulative concerns (as are all human health standards for all metals). It is still necessary
to evaluate total recoverable aquatic life and human health standards listed in 15A NCAC
2B.0200(e.g., arsenic at 10 µg/1 for human health protection; cyanide at 5 µg/L and fluoride at
1.8 mg/L for aquatic life protection).
Table 2.Dissolved Freshwater Standards for Hardness-Dependent Metals
The Water Effects Ratio(WER)is equal to one unless determined otherwise under 15A
NCAC 02B .0211 Subparagraph(11)(d)
Metal NC Dissolved Standard, µg/I
Cadmium,Acute WER*{1.136672-[ln hardness](0.041838)} e^10.9151 [ln hardness]-3.1485}
Cadmium,Acute Trout waters WER*{1.136672-[ln hardness](0.041838)} e^{0.9151[In hardness]-3.62361
Cadmium,Chronic WER*{1.101672-[ln hardness](0.041838)} •e^{0.7998[ln hardness]-4.445 11
Chromium III,Acute WER*0.316 e^{0.8190[ln hardness]+3.7256}
Chromium III,Chronic WER*0.860 e^{0.8190[ln hardness]+0.6848}
Copper,Acute WER*0.960 e^{0.9422[ln hardness]-1.700}
Copper,Chronic WER*0.960 e^{0.8545[ln hardness]-1.702}
Lead,Acute WER*{1.46203-[ln hardness](0.145712)} • e^{1.273[ln hardness]-1.460}
Lead,Chronic WER*{1.46203-[ln hardness](0.145712)} •e^{1.273[ln hardness]-4.705)
Nickel,Acute WER*0.998 e^{0.8460[ln hardness]+2.255}
Nickel,Chronic WER*0.997 e^{0.8460[ln hardness]+0.0584}
Page 1 of 4

Permit No. NCO043176
Silver,Acute WER*0.85 •e^{1.72[ln hardness]-6.59}
Silver,Chronic Not applicable
Zinc,Acute WER*0.978 e^{0.8473[ln hardness]+0.884}
Zinc,Chronic WER*0.986 e^{0.8473[ln hardness]+0.884}
General Information on the Reasonable Potential Analysis (RPA)
The RPA process itself did not change as the result of the new metals standards. However, application of
the dissolved and hardness-dependent standards requires additional consideration in order to establish the
numeric standard for each metal of concern of each individual discharge.
The hardness-based standards require some knowledge of the effluent and instream(upstream)hardness
and so must be calculated case-by-case for each discharge.
Metals limits must be expressed as `total recoverable' metals in accordance with 40 CFR 122.45(c). The
discharge-specific standards must be converted to the equivalent total values for use in the RPA
calculations. We will generally rely on default translator values developed for each metal(more on that
below),but it is also possible to consider case-specific translators developed in accordance with
established methodology.
RPA Permitting Guidance/WOBELs for Hardness-Dependent Metals -Freshwater
The RPA is designed to predict the maximum likely effluent concentrations for each metal of concern,
based on recent effluent data, and calculate the allowable effluent concentrations,based on applicable
standards and the critical low-flow values for the receiving stream.
If the maximum predicted value is greater than the maximum allowed value(chronic or acute),the
discharge has reasonable potential to exceed the standard,which warrants a permit limit in most cases. If
monitoring for a particular pollutant indicates that the pollutant is not present(i.e. consistently below
detection level),then the Division may remove the monitoring requirement in the reissued permit.
1. To perform a RPA on the Freshwater hardness-dependent metals the Permit Writer compiles the
following information:
• Critical low flow of the receiving stream, 7Q10(the spreadsheet automatically calculates
the 1 Q 10 using the formula 1 Q 10=0.843 (s7Q 10, cfs)0.993
• Effluent hardness and upstream hardness, site-specific data is preferred
• Permitted flow
• Receiving stream classification
2. In order to establish the numeric standard for each hardness-dependent metal of concern and for
each individual discharge,the Permit Writer must first determine what effluent and instream
(upstream)hardness values to use in the equations.
The permit writer reviews DMR's,Effluent Pollutant Scans, and Toxicity Test results for any
hardness data and contacts the Permittee to see if any additional data is available for instream
hardness values,upstream of the discharge.
If no hardness data is available,the permit writer may choose to do an initial evaluation using a
default hardness of 25 mg/L(CaCO3 or(Ca+Mg)). Minimum and maximum limits on the
hardness value used for water quality calculations are 25 mg/L and 400 mg/L,respectively.
If the use of a default hardness value results in a hardness-dependent metal showing reasonable
potential,the permit writer contacts the Permittee and requests 5 site-specific effluent and
upstream hardness samples over a period of one week. The RPA is rerun using the new data.
Page 2 of 4

Permit No. NCO043176
The overall hardness value used in the water quality calculations is calculated as follows:
Combined Hardness(chronic)
_(Permitted Flow,cfs *Avg. Effluent Hardness,mg/L)+s7Q10, cfs *Avg. Upstream Hardness,mg/L)
(Permitted Flow,cfs+s7Q10,cfs)
The Combined Hardness for acute is the same but the calculation uses the IQ 10 flow.
3. The permit writer converts the numeric standard for each metal of concern to a total recoverable
metal,using the EPA Default Partition Coefficients(DPCs)or site-specific translators, if any
have been developed using federally approved methodology.
EPA default partition coefficients or the"Fraction Dissolved"converts the value for
dissolved metal at laboratory conditions to total recoverable metal at in-stream
ambient conditions. This factor is calculated using the linear partition coefficients
found in The Metals Translator: Guidance for Calculating a Total Recoverable
Permit Limit from a Dissolved Criterion (EPA 823-B-96-007, June 1996)and the
equation:
Cdiss - 1
Ctotal I + { [Kpo] [ss('+a)] [10-6] }
Where:
ss=in-stream suspended solids concentration [mg/1],minimum of 10 mg/L used,
and
Kpo and a=constants that express the equilibrium relationship between dissolved
and adsorbed forms of metals. A list of constants used for each hardness-dependent
metal can also be found in the RPA program under a sheet labeled DPCs.
4. The numeric standard for each metal of concern is divided by the default partition coefficient(or
site-specific translator)to obtain a Total Recoverable Metal at ambient conditions.
In some cases,where an EPA default partition coefficient translator does not exist(ie. silver),the
dissolved numeric standard for each metal of concern is divided by the EPA conversion factor to
obtain a Total Recoverable Metal at ambient conditions. This method presumes that the metal is
dissolved to the same extent as it was during EPA's criteria development for metals. For more
information on conversion factors see the June, 1996 EPA Translator Guidance Document.
5. The RPA spreadsheet uses a mass balance equation to determine the total allowable concentration
(permit limits)for each pollutant using the following equation:
Ca=(s7Q 10+Qw)(Cwgs)—(s7Q 10) (Cb)
Qw
Where: Ca=allowable effluent concentration(µg/L or mg/L)
Cwqs=NC Water Quality Standard or federal criteria(µg/L or mg/L)
Cb=background concentration: assume zero for all toxicants except NH3* (µg/L or mg/L)
Qw=permitted effluent flow(cfs,match s7Q 10)
s7Q 10=summer low flow used to protect aquatic life from chronic toxicity and human
health through the consumption of water, fish, and shellfish from noncarcinogens (cfs)
* Discussions are on-going with EPA on how best to address background concentrations
Flows other than s7Q 10 may be incorporated as applicable:
IQ 10=used in the equation to protect aquatic life from acute toxicity
Page 3 of 4

Permit No. NC0043176
QA=used in the equation to protect human health through the consumption of water,
fish, and shellfish from carcinogens
30Q2=used in the equation to protect aesthetic quality
6. The permit writer enters the most recent 2-3 years of effluent data for each pollutant of concern.
Data entered must have been taken within four and one-half years prior to the date of the permit
application(40 CFR 122.21). The RPA spreadsheet estimates the 95th percentile upper
concentration of each pollutant. The Predicted Max concentrations are compared to the Total
allowable concentrations to determine if a permit limit is necessary. If the predicted max exceeds
the acute or chronic Total allowable concentrations,the discharge is considered to show
reasonable potential to violate the water quality standard, and a permit limit(Total allowable
concentration)is included in the permit in accordance with the U.S. EPA Technical Support
Document for Water Quality-Based Toxics Control published in 1991.
7. When appropriate,permit writers develop facility specific compliance schedules in accordance
with the EPA Headquarters Memo dated May 10,2007 from James Hanlon to Alexis Strauss on
40 CFR 122.47 Compliance Schedule Requirements.
8. The Total Chromium NC WQS was removed and replaced with trivalent chromium and
hexavalent chromium Water Quality Standards. As a cost savings measure,total chromium data
results may be used as a conservative surrogate in cases where there are no analytical results
based on chromium III or VI. In these cases,the projected maximum concentration(95th%) for
total chromium will be compared against water quality standards for chromium III and
chromium VI.
9. Effluent hardness sampling and instream hardness sampling,upstream of the discharge, are
inserted into all permits with facilities monitoring for hardness-dependent metals to ensure the
accuracy of the permit limits and to build a more robust hardness dataset.
10. Hardness and flow values used in the Reasonable Potential Analysis for this permit included:
Parameter Value Comments (Data Source)
Average Effluent Hardness(mg/L) 35 Average of 2020, 2021 and
[Total as, CaCO31 2022 Effluent Pollutant Scans
Average Upstream Hardness (mg/L) 26.6 Average from MCFBA Station
[Total as, CaCO31 B7480000112019—1212022
7Q10 summer(cfs) 586.6 Historical;Previous Fact Sheet
1Q10(cfs) 472.92 Calculated in RPA
Permitted Flow(MGD) 3.75 NPDES Files
Date: 10/23/2023
Permit Writer: Nick Coco
Page 4 of 4

NH3/TRC WLA Calculations
Facility: Black River WWTP
PermitNo. NC0043176
Prepared By: Nick Coco
Enter Design Flow (MGD): 3.75
Enter s7Q10 (cfs): 586.6
Enter w7Q10 (cfs): 586.6
Total Residual Chlorine (TRC) Ammonia (Summer)
Daily Maximum Limit (ug/1) Monthly Average Limit(mg NH3-N/1)
s7Q10 (CFS) 586.6 s7Q10 (CFS) 586.6
DESIGN FLOW (MGD) 3.75 DESIGN FLOW (MGD) 3.75
DESIGN FLOW (CFS) 5.8125 DESIGN FLOW (CFS) 5.8125
STREAM STD (UG/L) 17.0 STREAM STD (MG/L) 1.0
Upstream Bkgd (ug/1) 0 Upstream Bkgd (mg/1) 0.22
IWC (%) 0.98 IWC (%) 0.98
Allowable Conc. (ug/1) 1733 Allowable Conc. (mg/1) 79.7
Cap at 28 ug/L. Less stringent than current limit.Maintain limit.
Consistent with current limit.Maintain limit.
Ammonia (Winter)
Monthly Average Limit(mg NH3-N/1)
Fecal Coliform w7Q10 (CFS) 586.6
Monthly Average Limit: 200/100m1 DESIGN FLOW (MGD) 3.75
(If DF >331; Monitor) DESIGN FLOW (CFS) 5.8125
(If DF<331; Limit) STREAM STD (MG/L) 1.8
Dilution Factor(DF) 101.92 Upstream Bkgd (mg/1) 0.22
IWC (%) 0.98
Allowable Conc. (mg/1) 161.3
Less stringent than current limit.Maintain limit.
Total Residual Chlorine
1. Cap Daily Max limit at 28 ug/l to protect for acute toxicity
Ammonia (as NH3-N)
1. If Allowable Conc > 35 mg/l, Monitor Only
2. Monthly Avg limit x 3 = Weekly Avg limit (Municipals)
3. Monthly Avg limit x 5 = Daily Max limit(Non-Munis)
If the allowable ammonia concentration is > 35 mg/L, no limit shall be imposed
Fecal Coliform
1. Monthly Avg limit x 2 =400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non-Muni)

10/24/23 WQS= 12 ng/L MERCURY WQBEL/TBEL EVALUATION V:2013-6
Facility Name Black River WWTP/NC0043176 No Limit Required
/Permit No.
MMP Required
Total Mercury 1631E PQL=0.5 ng/L 7Q10s = 586.600 cfs WQBEL= 1223.05 ng/L
Date Modifier Data Entry Value Permitted Flow= 3.750 47 ng/L
12/8/20 3.94 3.94 3.9 ng/L-Annual Average for 2020
9/13/21 5.23 5.23 5.2 ng/L-Annual Average for 2021
6/6/22 1.99 1.99 2.0 ng/L-Annual Average for 2022

Black River WWTP/NC0043176
Mercury Data Statistics (Method 1631E)
2020 2021 2022
#of Samples 1 1 1
Annual Average, ng/L 3.9 5.2 2.0
Maximum Value, ng/L 3.94 5.23 1.99
TBEL, ng/L 47
WQBEL, ng/L 1223.0

NCO043176 Black River WWTP 10/4/2023
BOD monthly removal rate TSS monthly removal rate
Month RR(%) Month RR(%) Month RR(%) Month RR(%)
March-19 95.31 September-21 96.30 March-19 96.53 September-21 92.85
April-19 96.07 October-21 97.79 April-19 96.33 October-21 97.03
May-19 97.09 November-21 97.50 May-19 97.05 November-21 94.23
June-19 96.54 December-21 97.81 June-19 96.34 December-21 96.70
July-19 97.54 January-22 95.68 July-19 97.51 January-22 95.70
August-19 98.10 February-22 96.68 August-19 96.11 February-22 94.92
September-19 97.42 March-22 97.82 September-19 95.58 March-22 97.45
October-19 96.91 April-22 97.46 October-19 94.21 April-22 96.95
November-19 95.50 May-22 97.43 November-19 96.32 May-22 97.65
December-19 93.67 June-22 97.84 December-19 94.24 June-22 98.05
January-20 89.75 July-22 96.66 January-20 93.44 July-22 97.80
February-20 85.63 August-22 97.87 February-20 93.56 August-22 97.41
March-20 91.12 September-22 97.70 March-20 94.74 September-22 98.05
April-20 94.63 October-22 97.53 April-20 94.12 October-22 97.19
May-20 96.69 November-22 97.44 May-20 96.02 November-22 96.98
June-20 93.46 December-22 95.81 June-20 95.90 December-22 94.87
July-20 94.41 January-23 97.29 July-20 94.87 January-23 96.91
August-20 92.98 February-23 96.40 August-20 93.52 February-23 93.61
September-20 93.66 March-23 97.40 September-20 96.51 March-23 96.95
October-20 96.52 April-23 95.86 October-20 96.32 April-23 95.72
November-20 94.83 May-23 96.69 November-20 95.67 May-23 96.57
December-20 95.52 June-23 97.94 December-20 93.69 June-23 98.27
January-21 90.71 July-23 94.99 January-21 85.31 July-23 94.13
February-21 82.66 August-23 94.26 February-21 84.13 August-23 96.59
March-21 86.76 September-23 March-21 63.48 September-23
April-21 95.29 October-23 April-21 87.72 October-23
May-21 95.86 November-23 May-21 89.83 November-23
June-21 96.22 December-23 June-21 93.13 December-23
July-21 94.58 January-24 July-21 92.16 January-24
August-21 97.19 February-24 August-21 94.91 February-24
Overall BOD removal rate 95.37 Overall TSS removal rate 94.44

Reduction in Frequency Evalaution
Facility: Black River WWTP
Permit No. NC0043176
Review period(use 3 8/2020-8/2023
yrs)
Approval Criteria: Y/N?
1. Not currently under SOC Y
2. Not on EPA Quarterly noncompliance report Y
3.Facility or employees convicted of CWA N
violations
Weekly Monthly 500/ 200% 200/ monthly #civil penalty 3-yr mean #daily #daily #of non-
p Reduce
Data Review Units average (geo mean <50%? samples <15? samples <20? >2? >1? Frequency?
average limit limit MA for FC) MA >200% WA >200% limit asessment (Yes/No)
violations
BOD(Weighted) mg/L 25.5 17 8.5 3.5981308 Y 34 0 Y 0 N 0 N Y
TSS mg/L 45 30 15 4.7027595 Y 60 1 Y 0 N 0 N Y
Ammonia(weighted) mg/L 8.5 2.83333 1.4 0.3901816 Y 1 5.67 3 Y 0 N 0 N Y
Fecal Coliform #/100 400 200 100 1 1.7458761 Y 800 8 Y 0 N 0 N Y

MONITORING REPORT(MR)VIOLATIONS for: Report Date: 10/02/22 Page 1 of 1
Permit: NCO043176 MRS Betweei 9 - 2018 and 9 - 2023 Region: % Violation Category:Limit Violation Program Category:
Facility Name:% Param Nam(% County: % Subbasin:% Violation Action:%
Major Minor: %
PERMIT: NCO043176 FACILITY: City of Dunn-Dunn WWTP COUNTY: Harnett REGION: Fayetteville
Limit Violation
MONITORING VIOLATION UNIT OF CALCULATED %
REPORT OUTFALL LOCATION PARAMETER DATE FREQUENCY MEASURE LIMIT VALUE Over VIOLATION TYPE VIOLATION ACTION
12-2018 001 Effluent Flow,in conduit or thru 12/31/18 Continuous mgd 3.75 4.555 21.5 Monthly Average Proceed to
treatment plant Exceeded Enforcement Case
01-2019 001 Effluent Flow,in conduit or thru 01/31/19 Continuous mgd 3.75 4.113 9.7 Monthly Average Proceed to NOV
treatment plant Exceeded
01-2020 001 Effluent Flow,in conduit or thru 01/31/20 Continuous mgd 3.75 3.898 4.0 Monthly Average None
treatment plant Exceeded
01-2020 001 Effluent Flow,in conduit or thru 01/31/20 Continuous mgd 3.75 3.907 4.2 Monthly Average Proceed to NOV
treatment plant Exceeded
02-2020 001 Effluent Flow,in conduit or thru 02/29/20 Continuous mgd 3.75 4.533 20.9 Monthly Average None
treatment plant Exceeded
02-2020 001 Effluent Flow,in conduit or thru 02/29/20 Continuous mgd 3.75 4.533 20.9 Monthly Average Proceed to
treatment plant Exceeded Enforcement Case
06-2020 001 Effluent Flow,in conduit or thru 06/30/20 Continuous mgd 3.75 3.955 5.5 Monthly Average Proceed to NOV
treatment plant Exceeded
08-2020 001 Effluent Flow,in conduit or thru 08/31/20 Continuous mgd 3.75 3.79 1.1 Monthly Average Proceed to NOD
treatment plant Exceeded
12-2020 001 Effluent Flow,in conduit or thru 12/31/20 Continuous mgd 3.75 3.794 1.2 Monthly Average Proceed to NOD
treatment plant Exceeded
01-2021 001 Effluent Flow,in conduit or thru 01/31/21 Continuous mgd 3.75 5.257 40.2 Monthly Average Proceed to
treatment plant Exceeded Enforcement Case
02-2021 001 Effluent Flow,in conduit or thru 02/28/21 Continuous mgd 3.75 5.823 55.3 Monthly Average Proceed to
treatment plant Exceeded Enforcement Case
03-2021 001 Effluent Flow,in conduit or thru 03/31/21 Continuous mgd 3.75 3.79 1.1 Monthly Average Proceed to NOV
treatment plant Exceeded

The City of Dunn has one wastewater treatment plant, located at 580 J.W. Edwards Lane. This
plant is known as the Black River Wastewater Treatment Plant. The first plant at this site was
constructed in the 1920's and has been upgraded and expanded several times since. In 1995,the
plant was expanded and was permitted to a capacity of 3.75 MGD. In 2010 another upgrade
began with the influent pump station, influent screening, grit removal, a flow equalization tank
and fine bubble diffused aeration in digester. The latest upgrade to the plant began in 2023 and
includes a new diversion box at the end of aeration basin, one 80 ft. clarifier, new chlorine
contact chamber, chemical feed building. These improvements have optimized the plant
operations and capabilities.
The WWTP includes the following individual processes.
Summary Process
Process Description
Influent Pumping
Two 2,100 GPM suction lift pumps
Two 3,500 GPM suction lift pumps
Two mechanically cleaned bar screens with 1/4" bar
spacing and screening compactor
Influent Screening One manually cleaned bypass bar screen with 1/2" bar
spacing
One grit concentrator
Grit Removal One grit washing unit
One grit dewatering escalator
Flow Equalization One 3.0 million gallon tank
Two 2,100 GPM suction lift pumps
Activated Sludge Basin One aeration basin with fine bubble diffused aeration
Three 3150 SUM Positive displacement blowers blowers
Clarifiers Three 60 ft. circular bottom scraper clarifiers and one 80
ft. clarifier being constructed
Chlorine Disinfection 12.5%Sodium Hypochlorite
40%sodium Bisulfite
Sludge Thickening One 150 GPM Rotary Drum Thickener
One 125,000 gallon basin with fine bubble diffused
Aerated Sludge Digestion aeration
Three 375 SUM positive displacement blowers
Sludge Holding One600,000 gallon sludge holding tank with aeration
Effluent Pumping Three 4,600 GPM Vertical Turbine Pumps

The Dunn Wastewater Collection system consists of approximately 75 miles of sewer lines and
nine liftstations. Wastewater enters the site by gravity from the collection system and flows into
the influent wet well, located within the influent pump station(TPS).Here it is pumped approx.,
14 feet upwards by suction lift pumps and discharged into the Primary Treatment Facility. The
wastewater is then diverted into either one or both Mechanical Bar Screens where debris is
removed. Screenings are compacted and conveyed to a dumpster for disposal in a solid waste
facility.
Before leaving the primary treatment facility, the wastewater flows through a 24"parshall flume
so that accurate process flow measurements can be recorded.
During high flow periods,part of the wastewater can be diverted into the Equalization Wet Well,
where it is them pumped to the 3 million gallon Equalization Basin. The wastewater can remain
in the basin until peak flows have subsided and the influent flow is below the plant capacity. At
this point wastewater held in the Equalization Basin can be directed to the Aeration Basin and
continue processing.
The influent wastewater coming from the Primary Treatment Facility and any return wastewater
from the Equalization Basin then meet in the Aeration Basin Junction Box. Return activated
sludge (RAS) and supernatant from the Rotary Drum Thickener are also piped into this box. The
flow leaves via two 24"pipes and enters the Aeration Basin.
Once the wastewater has entered the aeration basin, fine bubble diffused air agitates the water,
introducing oxygen and allowing the wastewater to be consumed by the bacteria present in the
activated sludge mixed liquor. The basin has a detention time of 18 hours before the water exits
the basin via overflow weirs and is distributed to the three Clarifiers.
The Clarifiers are conventional circular center feed,peripheral overflow devices. Each unit is
equipped with a center feed well, sludge suction tubes, and effluent v-notch weir plates. Each
unit also has a drive motor attached to a mechanic scraper for solids removal. We are currently
under construction and a fourth clarifier is being added.
The low surface overflow rates in the clarifiers allows the sludge to settle to the bottom, while
clarified water exits each clarifier basin over a effluent v-notch weir,where it is then piped to a
junction box. From there,the treater water enters the Chlorine contact basin. A new Chlorine
Contact Basin is being constructed as part of this upgrade.
As water enters the Contact Basin,it is mixed with a sodium hypochlorite solution(chlorine)to
disinfect any organisms present. The contact Basin provides a contact time of at least 30 minute
before the effluent exits and flows through a parshall flume. After leaving the parshall flume,the
effluent is injected with sodium bisulfite to neutralize the chlorine. Effluent then travels to the
Effluent Pump Station Wet Well,where it is pumped to the Cape Fear River and discharged.
The sludge pump station wet well receives RAS flow from all three clarifiers. RAS is pumped
via suction lift pumps to a sludge control vault,where electrically actuated valves are provided to
control flow rate and divert waste activated sludge (WAS)to the Rotary Dum Thickener.Each

sludge line is equipped with a magnetic flow meter to provide an indication of flow rate and
volume of sludge.
Once the thickened sludge leaves the Rotary Drum Thickener, it is pumped via mono-pumps to
the digester. The digester includes a sludge feed line, floating decanter, sludge withdrawal line,
and aeration diffusers.
Digested sludge can be pumped from the digester to the sludge holding tank. The holding tank
has a floating mixer and also has aeration capabilities, to keep solids suspended and prevent
septic conditions.
Three positive displacement blowers provide air to both the digester and the holding tank to
fiirther breakdown solids.
Several times a year, sludge from the sludge holding tank is loaded onto trucks and taken offsite
for land application. Presently the city uses Granville Farms for sludge management.
i
i
I

NC Department of Environment and Natural Resources
Model Mercury Minimization Plan
Background
The North Carolina Department of Environment and Natural Resources,Division of Water Resources
(DENR),has issued a statewide total maximum daily load(TMDL)for mercury. The TMDL responds to
a statewide fish consumption advisory for mercury. The TMDL calls for a 67%reduction in mercury
levels from the year 2002 baseline mercury loading. The ultimate goal of the TMDL is to ensure safe-
levels of mercury in fish throughout North Carolina for human consumption.
As explained in the TMDL, 98 percent of mercury in North Carolina waters comes from atmospheric
sources—the vast majority of which are located outside of the State. Under the Clean Water Act,
atmospheric deposition of mercury into surface waters is regarded as a nonpoint source. Minor amounts
of mercury are discharged directly into surface waters by industrial and municipal point sources as a
group. Specifically,the TMDL determined that point sources contribute less than two (2)percent of the
annual mercury loadings to State waters. The TMDL allocates two percent of the statewide allowable
loadings collectively to the point source sector. This does not mean that an individual discharger may not
have significant levels of mercury in its discharge in terms of local water quality considerations. While
we expect such instances to be rare based upon the Department's review of statewide mercury data,
dischargers with higher mercury loadings will be expected to implement more aggressive mercury
controls.
Notably,unlike any other source, local governments actually reduce mercury loadings in the environment
by first filtering mercury out in the treatment of public drinking water(particularly where the source of
raw drinking water is surface water) and then a second time when wastewater is treated.
In order to implement the two percent point source sector wasteload allocation,the Department has
developed a point source permitting strategy which is located at htW:Hdeq.nc.gov/about/divisions/water-
resources/planning/modeling-assessment/special-studies/mercury tmdl. The Environmental Management
Commission has approved both the TMDL and the Permitting Strategy. The permitting strategy calls for
certain point sources to develop and implement mercury minimization plans (MMPs). For POTWs, an
MMP will be required if the facility has (1) a permitted design capacity of more than two million gallons
per day and(2)mercury at quantifiable levels in their effluent. MMPs feature best management practices
and have been implemented successfully in numerous states around the country. The attached document
is Black River Wastewater Treatment's MMP.
Typically,MMPs focus on pretreatment controls—a local government's interaction with non-domestic
users of its sewer system as well as outreach to the public at large regarding the proper use and disposal of
household products containing mercury.
The MMP approach is intended as a reasonable, low-cost approach toward making some progress toward
managing the two percent loading statewide from point sources. Mercury treatment and even testing is
very expensive and does not make sense to reduce a small part of the already insignificant two percent
overall point source annual loading to State waters.

City of Dunn
Black River Wastewater Treatment Plant
MUNICIPAL MERCURY MINIMIZATION PLAN
9/9/19
SECTION I-PURPOSE
The purpose of this Mercury Minimization Plan("MMP")is to describe best management practices
through which The Black River Wastewater Treatment Plant will seek to reduce the amount of
mercury discharged into its system and,ultimately,to the environment. The MMP compiles mercury
reduction-related efforts to-date and potential future action items. It is designed to be a working
document to help guide The City of Dunn in its efforts to control mercury loadings discharged into its
Publicly-Owned Treatment Works (POTW)by users of the sewer system. Such a reduction in loadings to
the sewer system should translate to a reduction in the amount of mercury which is discharged from the
treatment plant. The management practices summarized below may also help control some of the
mercury reaching our storm sewer system as well.
SECTION II—FACILITY DESCRIPTION
The City of Dunn operates a publicly owned treatment works (POTW), including a collection system and
wastewater treatment plant(WWTP),that serves Dunn,North Carolina.
The Black River Wastewater Treatment Plant is a Biological Activated Sludge facility permitted for
3.75MGD and consisting of the following:
• Influent pumps
• Equalization tank(3,000,000gallons)
• Automatic bar screens
• Grit removal
• Aeration basins
• Three final clarifiers
• Chlorination system(sodium hypochlorite liquid)
• Dechlorination system(Sodium bisulfate liquid)
• Chlorine contact chambers
• Effluent pumps
• Cascade discharge
• Sludge handling consisting of RDT, aerobic digester, aerated sludge holding tank.
Most municipal treatment plants are not designed to remove mercury and it is exceedingly expensive to
do so to very low levels. Incidental mercury removal occurs through typical municipal treatment with
trace levels of mercury(and other metals)ending up in solids removed from the raw wastewater.
Mercury is not used in the treatment processes at the WWTP. Mercury may be introduced into the sewer
system through a variety of sources, such as from industrial users, laboratories, and other businesses.
Residual deposits of mercury are also possible in the sewer system from historic practices. Finally,trace
amounts from household products and atmospheric deposition(both wet and dry)contribute to sewer
system mercury loadings.

While there is typically some mercury contributed to public sewer systems statewide, it is usually in
minute quantities and comprises a tiny portion of the already insignificant statewide loading for all point
sources-just two percent of the annual mercury loadings to all State waters.
SECTION III—PROGRAM PLAN
A. EVALUATION OF POTENTIAL NON-DOMESTIC SOURCES CONTRIBUTING
MERCURY TO THE POTW
Within 24 months from the NPDES required 180-day period for development of an MMP, ,the
BRWWTP will evaluate available information to assess the potential for non-domestic users of the sewer
system to contribute mercury to the system. The information to be reviewed may include: (1)POTW
influent and effluent mercury data and trends; (2)industrial user permits and associated mercury
monitoring data; (3)Toxics Release Inventory(TRI); (4) state hazardous site registry and the National
Priority List relating to mercury contamination; and(5)historical records of industrial sites which may
have contributed mercury loadings to the sewer system.
The BRWWTP will also survey and evaluate the following common sources of mercury in its service
area: (1)dentist offices; (2)hospitals; (3) laboratories; (4)auto recyclers; and(5) other potential sources
of mercury based on existing information.
The BRWWTP will request that industrial users review mercury concentrations in high-volume process
chemicals and demonstrate that the mercury concentrations are below industry average. The BRWWTP
will request that alternative sources for chemicals be explored if the mercury levels are determined to be
significantly higher than would normally be expected.
The evaluation of potential non-domestic sources of mercury to the sewer system will be updated every
five years, as warranted by prior sampling results and any additional new potentially significant sources to
the system.
B. ADDITIONAL CONTROL MEASURES
This MMP identifies reasonable and cost-effective control measures to minimize mercury being
discharged into the POTW. Below is a listing of initial BMPs for this POTW.
Pollution Prevention
Substances used at the WWTP will be evaluated to determine if they contain mercury or mercury-based
compounds. Any such chemicals will be evaluated for substitution with non-mercury-containing
substances.
Housekeeping,Spill Control and Collection,and Education
The BRWWTP will develop procedures to minimize the possibility of any spill or release at the WWTP
involving mercury containing substances. BRWWTP will add mercury identification and proper
disposal to ongoing and future operator training procedures.

Laboratory Practice
The BRWWTP operates a laboratory for purposes of complying with state and federal monitoring and
sampling requirements. The laboratory is a potential source of small quantities of mercury-containing
compounds. Laboratory employees will be trained in the proper handling and disposal of these materials.
The laboratories have also replaced mercury thermometers with non-mercury thermometers,whenever
practical.
C. TRACKING AND MONITORING
In order to assess the implementation of the control measures,the BRWWTP proposes to undertake the
following evaluations beginning after the first full year that this MMP is implemented:
1. Survey annually at least ten percent(10%) of any non-domestic users identified as
possible significant sources of mercury to the POTW;
2. Track the implementation of the programs outlined above;
3. Measure effluent mercury as required by the NPDES permit.
These efforts will allow the BRWWTP to assist in identifying any trends in mercury contributions from
domestic and non-domestic users of the sewer system. This will be tracked annually with the priority
pollutants scan required by the NPDES permit.
SECTION IV —IMPLEMENTATION OF CONTROL MEASURES
[Insert discussion of any prior efforts at utility to minimize actual or potential sources of mercury
to wastewater(e.g.,the collection and proper disposal of mercury-containing equipment at the
POTW; implementation of the pretreatment program; local limits for mercury)]
The BRWWTP will implement the control measures summarized in Section III over the permit term and
will update this MMP as warranted.
SECTION V- REPORTING
A summary of the MMP activities will be documented and kept on sight, as part of the NPDES permit
renewal process.

United States Environmental Protection Agency Form Approved.
EPA Washington,D.C.20460 OMB No.2040-0057
Water Compliance Inspection Report Approval expires 8-31-98
Section A: National Data System Coding (i.e., PCS)
Transaction Code NPDES yr/mo/day Inspection Type Inspector Fac Type
1 IN 1 2 u 3 I NCO043176 I11 121 21/12/07 I17 181 B I 19 I G I 201 I
211IIIII 111111III II III III1 I I IIIII IIIIIIIII II r6
Inspection Work Days Facility Self-Monitoring Evaluation Rating B1 QA ----------------------Reserved-------------------
67 70 J 71 pty 72 L-J 73 1 74 79 I I I I 80
Section B: Facility Data
Name and Location of Facility Inspected(For Industrial Users discharging to POTW,also include Entry Time/Date Permit Effective Date
POTW name and NPDES permit Number) 09:30AM 21/12/07 19/04/01
Dunn WWTP
Susan Tart Rd Exit Time/Date Permit Expiration Date
Dunn NC 28335 01:30PM 21/12/07 23/09/30
Name(s)of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s) Other Facility Data
Donrie Eldridge Dukes/ORC/910-892-8162/
Name,Address of Responsible Official/Title/Phone and Fax Number
Contacted
Steven Neuschafer,PO Box 1065 Dunn NC 28335//910-892-2633/
No
Section C:Areas Evaluated During Inspection (Check only those areas evaluated)
Permit 0 Flow Measurement Operations&Maintenar Records/Reports
Self-Monitoring Progran 0 Sludge Handling Dispo: Facility Site Review Effluent/Receiving Wate
Laboratory
Section D: Summary of Finding/Comments(Attach additional sheets of narrative and checklists as necessary)
(See attachment summary)
Name(s)and Signature(s)of Inspector(s) Agency/Office/Phone and Fax Numbers Date
Stephanie Zorio DWR/FRO WQ/910-433-3322/
Signature of Management Q A Reviewer Agency/Office/Phone and Fax Numbers Date
Mark Brantley DWR/FRO WQ/910-433-3300 Ext.727/
EPA Form 3560-3(Rev 9-94)Previous editions are obsolete.
Page#

NPDES yr/mo/day Inspection Type (Cont.) 1
31 NCO043176 I11 12I 21/12/07 117 1$ I B I
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
All records, including an ORC log, were available at the time of the review and complete.
Facility grounds and laboratory were very well-maintained and orderly. Plant process controls include
MLSS, pH, DO, and sludge judge. The facilities permit expires in 2023. The plant continues to
operate under special permit conditions. Nutrient sampling continues monthly until the next permit
cycle. Additionally, the plant is on track to complete the requirement of monitoring for
Bis(2-Ethylhexyl)phthalate in Jan. 2022. Previous samples have all been non-detect. The plant
analyses fecal coliform, ammonia, and field parameters in-house. Other testing is contracted to
Environment One. DO temperature is calibrated with an NIST thermometer kept at the public water
plant. Staff sent documentation that the NIST thermometer was last calibrated in 2019 (valid for five
years).
DMRs from Jan. 2020 and Feb. 2020 were reviewed during the inspection. Two errors were found for
flow—one in January and one in February. Staff will submit amended DMRs as soon as possible.
Effluent was collected from Dunn WWTP's 24-hour composite equipment on December 7th and
December 9th, 2021, for chronic toxicity testing. The facility passed the chronic Ceriodaphnia dubia
pass/fail test performed by the DEQ Aquatic Toxicology Lab.
Dumpsters at the bar screen and grit chamber are emptied every Wednesday. Influent sampler
tubing contained a moderate amount of biofilm during the inspection. Wastewater pH is adjusted with
soda ash after wastewater leaves the aeration basin. Staff replaced the tubing by the end of the day.
The sludge blanket was measured at two of three secondary clarifiers. Sludge level was 0.5 ft. in the
10 ft. clarifier and 3 ft. in the 12 ft. clarifier.
The plant has two back-up generators. The 500 kw powers disinfection and effleuent pump station.
The 1000 kw can power the entire plant. Standby power is tested under load weekly. The facility
keeps records of testing and maintenance.
The aerobic digestor was empty at the time of inspection except for water sufficient enough to cover
the diffusers. The flow meter was calibrated on 1/26/2021. Solids handling equipment is torn down
and cleaned every 6 weeks. Sludge is hauled off by Granville Farms. As a member of the Cape Fear
River Basin Association the facility is exempt from performing their own upstream and downstream
sampling.
Page# 2

Permit: NCO043176 Owner-Facility: Dunn WWTP
Inspection Date: 12/07/2021 Inspection Type: Bioassay Compliance
Record Keeping Yes No NA NE
Are records kept and maintained as required by the permit? 0 ❑ ❑ ❑
Is all required information readily available, complete and current? 0 ❑ ❑ ❑
Are all records maintained for 3 years (lab. reg. required 5 years)? ■ ❑ ❑ ❑
Are analytical results consistent with data reported on DMRs? 0 ❑ ❑ ❑
Is the chain-of-custody complete? 0 ❑ ❑ ❑
Dates, times and location of sampling
Name of individual performing the sampling
Results of analysis and calibration
Dates of analysis
Name of person performing analyses
Transported COCs
Are DMRs complete: do they include all permit parameters? ❑ ❑ ❑
Has the facility submitted its annual compliance report to users and DWQ? ❑ ❑ ❑
(If the facility is = or> 5 MGD permitted flow) Do they operate 24/7 with a certified ❑ ❑ ❑
operator on each shift?
Is the ORC visitation log available and current? ❑ ❑ ❑
Is the ORC certified at grade equal to or higher than the facility classification? ❑ ❑ ❑
Is the backup operator certified at one grade less or greater than the facility ❑ ❑ ❑
classification?
Is a copy of the current NPDES permit available on site? 0 ❑ ❑ ❑
Facility has copy of previous year's Annual Report on file for review? 0 ❑ ❑ ❑
Comment: DMRs from Jan. 2020 and Feb. 2020 were reviewed during the inspection. Two errors
were found for flow—one in January and one in February. Staff will submit amended
DMRs as soon as possible.
Operations & Maintenance Yes No NA NE
Is the plant generally clean with acceptable housekeeping? 0 ❑ ❑ ❑
Does the facility analyze process control parameters, for ex: MLSS, MCRT, Settleable ❑ ❑ ❑
Solids, pH, DO, Sludge Judge, and other that are applicable?
Comment: Plant process controls include MLSS, pH, DO, and sludge fudge.
Permit Yes No NA NE
(If the present permit expires in 6 months or less). Has the permittee submitted a new ❑ ❑ 0 ❑
application?
Is the facility as described in the permit? 0 ❑ ❑ ❑
Page# 3

Permit: NCO043176 Owner-Facility: Dunn WWTP
Inspection Date: 12/07/2021 Inspection Type: Bioassay Compliance
Permit Yes No NA NE
#Are there any special conditions for the permit? 0 ❑ ❑ ❑
Is access to the plant site restricted to the general public? 0 ❑ ❑ ❑
Is the inspector granted access to all areas for inspection? 0 ❑ ❑ ❑
Comment: The facilities permit expires in 2023. The plant continues to operate under special
permit conditions. Nutrient sampling continues monthly until the next permit cycle.
Additionally, the plant is on track to complete the requirement of monitoring for
Bis(2-Ethylhexyl)phthalate in Jan. 2022. Previous samples have all been non-detect.
Standby Power Yes No NA NE
Is automatically activated standby power available? 0 ❑ ❑ ❑
Is the generator tested by interrupting primary power source? 0 ❑ ❑ ❑
Is the generator tested under load? 0 ❑ ❑ ❑
Was generator tested & operational during the inspection? ❑ ❑ ❑ ■
Do the generator(s) have adequate capacity to operate the entire wastewater site? 0 ❑ ❑ ❑
Is there an emergency agreement with a fuel vendor for extended run on back-up 0 ❑ ❑ ❑
power?
Is the generator fuel level monitored? ❑ ❑ ❑
Comment: The plant has two back-up generators. The 500 kw powers disinfection and effleuent
pump station. The 1000 kw can power the entire plant. Standby power is tested under
load weekly. The facility keeps records of testing and maintenance.
Bar Screens Yes No NA NE
Type of bar screen
a.Manual ❑
b.Mechanical
Are the bars adequately screening debris? 0 ❑ ❑ ❑
Is the screen free of excessive debris? ■ ❑ ❑ ❑
Is disposal of screening in compliance? ■ ❑ ❑ ❑
Is the unit in good condition? 0 ❑ ❑ ❑
Comment: Dumpsters at the bar screen and grit chamber are emptied every Wednesday.
Pump Station - Influent Yes No NA NE
Is the pump wet well free of bypass lines or structures? 0 ❑ ❑ ❑
Is the wet well free of excessive grease? 0 ❑ ❑ ❑
Are all pumps present? 0 ❑ ❑ ❑
Are all pumps operable? M ❑ ❑ ❑
Page# 4

Permit: NCO043176 Owner-Facility: Dunn WWTP
Inspection Date: 12/07/2021 Inspection Type: Bioassay Compliance
Pump Station - Influent Yes No NA NE
Are float controls operable? 0 ❑ ❑ ❑
Is SCADA telemetry available and operational? 0 ❑ ❑ ❑
Is audible and visual alarm available and operational? ❑ ❑ 0 ❑
Comment:
Grit Removal Yes No NA NE
Type of grit removal
a.Manual ❑
b.Mechanical
Is the grit free of excessive organic matter? ■ ❑ ❑ ❑
Is the grit free of excessive odor? 0 ❑ ❑ ❑
# Is disposal of grit in compliance? 0 ❑ ❑ ❑
Comment: Dumpsters at the bar screen and grit chamber are emptied every Wednesday.
Flow Measurement - Influent Yes No NA NE
# Is flow meter used for reporting? 0 ❑ ❑ ❑
Is flow meter calibrated annually? 0 ❑ ❑ ❑
Is the flow meter operational? 0 ❑ ❑ ❑
(If units are separated) Does the chart recorder match the flow meter? ❑ ❑ ❑
Comment: The flow meter was calibrated on 1/26/2021.
Secondary Clarifier Yes No NA NE
Is the clarifier free of black and odorous wastewater? 0 ❑ ❑ ❑
Is the site free of excessive buildup of solids in center well of circular clarifier? 0 ❑ ❑ ❑
Are weirs level? M ❑ ❑ ❑
Is the site free of weir blockage? 0 ❑ ❑ ❑
Is the site free of evidence of short-circuiting? ■ ❑ ❑ ❑
Is scum removal adequate? 0 ❑ ❑ ❑
Is the site free of excessive floating sludge? 0 ❑ ❑ ❑
Is the drive unit operational? 0 ❑ ❑ ❑
Is the return rate acceptable (low turbulence)? ■ ❑ ❑ ❑
Is the overflow clear of excessive solids/pin floc? 0 ❑ ❑ ❑
Is the sludge blanket level acceptable? (Approximately '/4 of the sidewall depth) 0 ❑ ❑ ❑
Page# 5

Permit: NCO043176 Owner-Facility: Dunn WWTP
Inspection Date: 12/07/2021 Inspection Type: Bioassay Compliance
Secondary Clarifier Yes No NA NE
Comment: The sludge blanket was measured at two of three secondary clarifiers. Sludge level
was 0.5 ft. in the 10 ft. clarifier and 3 ft. in the 12 ft. clarifier.
Aerobic Digester Yes No NA NE
Is the capacity adequate? ■ ❑ ❑ ❑
Is the mixing adequate? ❑ ❑ ■ ❑
Is the site free of excessive foaming in the tank? ❑ ❑ ■ ❑
# Is the odor acceptable? 0 ❑ ❑ ❑
# Is tankage available for properly waste sludge? 0 ❑ ❑ ❑
Comment: The aerobic digestor was empty at the time of inspection except for water sufficient
enough to cover the diffusers.
Solids Handling Equipment Yes No NA NE
Is the equipment operational? 0 ❑ ❑ ❑
Is the chemical feed equipment operational? ■ ❑ ❑ ❑
Is storage adequate? 0 ❑ ❑ ❑
Is the site free of high level of solids in filtrate from filter presses or vacuum filters? 0 ❑ ❑ ❑
Is the site free of sludge buildup on belts and/or rollers of filter press? ■ ❑ ❑ ❑
Is the site free of excessive moisture in belt filter press sludge cake? ■ ❑ ❑ ❑
The facility has an approved sludge management plan? 0 ❑ ❑ ❑
Comment: Solids handling equipment is torn down and cleaned every 6 weeks. Sludge is hauled
off by Granville Farms.
Drying Beds Yes No NA NE
Is there adequate drying bed space? ❑ ❑ 0 ❑
Is the sludge distribution on drying beds appropriate? ❑ ❑ 0 ❑
Are the drying beds free of vegetation? ❑ ❑ ■ ❑
# Is the site free of dry sludge remaining in beds? ❑ ❑ 0 ❑
Is the site free of stockpiled sludge? ❑ ❑ 0 ❑
Is the filtrate from sludge drying beds returned to the front of the plant? ❑ ❑ 0 ❑
# Is the sludge disposed of through county landfill? ❑ ❑ ■ ❑
# Is the sludge land applied? 0 ❑ ❑ ❑
(Vacuum filters) Is polymer mixing adequate? ❑ ❑ ❑
Comment: The drying beds have not been used for several years.
Page# 6

Permit: NCO043176 Owner-Facility: Dunn WWTP
Inspection Date: 12/07/2021 Inspection Type: Bioassay Compliance
Disinfection-Gas Yes No NA NE
Are cylinders secured adequately? 0 ❑ ❑ ❑
Are cylinders protected from direct sunlight? 0 ❑ ❑ ❑
Is there adequate reserve supply of disinfectant? ■ ❑ ❑ ❑
Is the level of chlorine residual acceptable? 0 ❑ ❑ ❑
Is the contact chamber free of growth, or sludge buildup? 0 ❑ ❑ ❑
Is there chlorine residual prior to de-chlorination? 0 ❑ ❑ ❑
Does the Stationary Source have more than 2500 Ibs of Chlorine (CAS No. ❑ ❑ 0 ❑
7782-50-5)?
If yes, then is there a Risk Management Plan on site? ❑ ❑ 0 ❑
If yes, then what is the EPA twelve digit ID Number? (1000- - )
If yes, then when was the RMP last updated?
Comment:
De-chlorination Yes No NA NE
Type of system ? Liquid
Is the feed ratio proportional to chlorine amount (1 to 1)? 0 ❑ ❑ ❑
Is storage appropriate for cylinders? 0 ❑ ❑ ❑
# Is de-chlorination substance stored away from chlorine containers? ❑ ❑ ❑
Comment:
Are the tablets the proper size and type? 0 ❑ ❑ ❑
Are tablet de-chlorinators operational? E ❑ ❑ ❑
Number of tubes in use?
Comment:
Pump Station - Effluent Yes No NA NE
Is the pump wet well free of bypass lines or structures? 0 ❑ ❑ ❑
Are all pumps present? 0 ❑ ❑ ❑
Are all pumps operable? 0 ❑ ❑ ❑
Are float controls operable? 0 ❑ ❑ ❑
Is SCADA telemetry available and operational? 0 ❑ ❑ ❑
Is audible and visual alarm available and operational? ❑ ❑ ❑
Comment:
Page# 7

Permit: NCO043176 Owner-Facility: Dunn WWTP
Inspection Date: 12/07/2021 Inspection Type: Bioassay Compliance
Effluent Pipe Yes No NA NE
Is right of way to the outfall properly maintained? 0 ❑ ❑ ❑
Are the receiving water free of foam other than trace amounts and other debris? ❑ ❑ ❑
If effluent (diffuser pipes are required) are they operating properly? ■ ❑ ❑ ❑
Comment:
Flow Measurement - Effluent Yes No NA NE
# Is flow meter used for reporting? 0 ❑ ❑ ❑
Is flow meter calibrated annually? 0 ❑ ❑ ❑
Is the flow meter operational? 0 ❑ ❑ ❑
(If units are separated) Does the chart recorder match the flow meter? ❑ ❑ 0 ❑
Comment:
Laboratory Yes No NA NE
Are field parameters performed by certified personnel or laboratory? 0 ❑ ❑ ❑
Are all other parameters(excluding field parameters) performed by a certified lab? ■ ❑ ❑ ❑
# Is the facility using a contract lab? 0 ❑ ❑ ❑
# Is proper temperature set for sample storage (kept at less than or equal to 6.0 0 ❑ ❑ ❑
degrees Celsius)?
Incubator (Fecal Coliform) set to 44.5 degrees Celsius+/- 0.2 degrees? 0 ❑ ❑ ❑
Incubator (BOD) set to 20.0 degrees Celsius +/- 1.0 degrees? M ❑ ❑ ❑
Comment: The plant analyses fecal coliform, ammonia, and field parameters in-house. Other
testing is contracted to Environment One.
Page# 8