NC0021024_Fact Sheet_20231003

Fact Sheet
NPDES Permit No. NCO021O24
Permit Writer / e-mail Contact: Gary Perlmutter / [e-mail]
Date: October 3, 2023
Division / Branch: NC Division of Water Resources / NPDES Municipal Permitting
Fact Sheet Template: Version 09Jan2017
Permitting Action:
❑X 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, three (3) effluent pollutant scans, four (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 Roxboro - Roxboro WWTP
Applicant Address:
P.O. Box 128, Roxboro, NC 27573
Facility Address:
902 Cavel-Chub Lake Rd, Roxboro, NC 27574
Permitted Flow:
5.0 MGD
Facility Type/Waste:
MAJOR Municipal; 96.0% domestic, 4.0% industrial'
Facility Class:
Grade IV
Treatment Units:
Septic Tank Unloading, Bar Screens, Grit Removal, Aeration Basins,
Secondary Clarifiers, Chlorination disinfection, De -chlorination,
Aerobic Digesters, Sludge Dewatering and Drying
Pretreatment Program (Y/N)
Yes, active
County:
Person
Region
Raleigh
Footnote.
1. Based on total permitted flow of 0.20 MGD.
Briefly describe the proposed permitting action and facility background: The City of Roxboro has applied
for NPDES permit renewal and submitted a renewal application, received by the Division on 11/22/2021.
Review of the application found it incomplete with the required four 2nd species Whole Effluent Toxicity
tests, the Process Narrative, and Chemical Addendum lacking. These items were received by request on

NC0021024
5/8/2023. The three required effluent pollutant scans were run in June 2019, September 2020 and March
2021; the four 2nd species tests were conducted in June 2019, March 2020, September 2020 and December
2020.
This facility serves a total population of —12,425 residents comprising populations of Roxboro (-8362),
and unincorporated areas of Person County (-4063). The facility operates a pretreatment program with two
(2) Significant Industrial Users (SIUs): Eaton Corp. (permitted flow = 0.15 MGD), a manufacturer, and
Spuntech Industries, LLC (permitted flow = 0.125 MGD), a textile facility.
The WWTP was issued Authorization to Construct (AtC) permit no. 021024A03 in August 2016 to make
the following system upgrades:
• Install a 2.4 MG multiple ring oxidation ditch system with surface rotors, pumps and controls;
• Repurpose two existing 3 MG aeration basins to 3 EQ basins of 3 MG, 1.3 MG and 1.3 MG and a
75,000-gal leachate tank plus install associated equipment;
• Install new EQ pump station with associated equipment;
• Install 2 new 500,000-gal digesters with associated equipment;
• Install 3 new blowers
• Replace 2 existing RAS/WAS pump stations with 3 new RAS pumps, 1 new scum pump, and 2
new WAS pumps;
• Install 2 new 1,150-gal sodium hypochlorite tanks in a repurposed roofed structure and associated
pump system and equipment
The AtC permitted upgrade construction is currently underway, and once completed will result in no
increase in design flow. The system component list on the permit's Supplement to Cover Sheet will reflect
the above changes.
Sludge management: The cover letter to the permit renewal application states: "Synagro Central land
applies the biosolid residuals generated from the operation of the WWTP per our land application permit
WQ0021826. "
2. Receiving Waterbody Information
Receiving Waterbody Information
Outfall(s) / Receiving Stream(s):
Outfall 001 / Marlowe Creek
Stream Segment:
22-58-12-6a
Stream Classification:
C
Drainage Area (mi2):
4.7
Summer 7Q10 (cfs):
0.0
Winter 7Q10 (cfs):
0.0
30Q2 (cfs):
0.0
Average Flow (cfs):
4.0
IWC (% effluent):
100
2022 303(d) listed / parameter:
Benthos
Subject to TMDL / parameter:
Statewide TMDL / Mercury
Basin / HUC:
Roanoke / 03010104
USGS Topo Quad:
Roxboro, NC
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The receiving stream, Marlowe Creek, has no downstream water supply waters before crossing the Virginia
state line at -10.6 miles downstream of the outfall.
3. Effluent Data Summary
Effluent data is summarized below for the period August 2018 through February 2023.
Table 1. Effluent Data Summary
Parameter
Units
Average
Max
Min
Permit Limit'
Flow
MGD
2.0
14.02
0.93
MA = 5.0
BOD, summer
mg/L
3.8
31.2
< 2.0
MA = 16.0
WA = 24.0
BOD, winter
mg/L
5.7
37.7
< 2.0
MA = 20.0
WA = 30.0
BOD removal
%
96.1
99.4
48.8
> 85
Total Suspended Solids
mg/L
4.3
42.0
2.3
MA = 30.0
(TSS)
WA = 45.0
TSS removal
%
95.5
99.8
18.4
> 85
Ammonia (NH3-N),
summer
mg/L
0.24
2.0
< 0.2
MA = 5.0
WA = 15.0
(through Oct 2021)
Ammonia (NH3-N),
winter
mg/L
0.26
1.5
< 0.2
MA = 13.0
(through Nov 2021)
WA = 35.0
Ammonia (NH3-N),
summer
mg/L
0.25
2.4
< 0.2
MA = 1.0
WA = 3.0
(beginning Apr 2022)
Ammonia (NH3-N),
winter
mg/L
0.36
3.00
< 0.2
MA = 1.8
(beginning Dec 2021)
WA = 5.4
Dissolved Oxygen (DO)
mg/L
7.2
9.4
5.1
DA > 5.0
pH
SU
7.0
7.5
6.6
6.0 - 9.0
Fecal Coliform
#/100 mL
7.4
> 2420
< 1
MA = 200
(geomean)
WA = 400
Total Residual Chlorine
µg/L
16.1
49
15
DM = 17 2
(TRC)
Temperature
°C
18.5
26.4
8.6
Monitor &
Report
Total Nitrogen
mg/L
7.83
22.30
1.65
Monitor &
Report
Total Phosphorus
mg/L
1.56
6.04
0.25
Monitor &
Report
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NCO021024
Parameter
Units
Average
Max
Min
Permit Limit'
Oil & Grease
mg/L
5.1
9
5
MA = 30.0
Total Copper
µg/L
8.3
32.0
3.6
MA = 14.8
DM = 21.0
Total Nickel
µg/L
2.1
< 10
0.5
Monitor &
Report
Total Zinc
µg/L
41
72
14
Monitor &
Report
Total Hardness
mg/L
g
48
76
36
Monitor &
(as CaCO3)
Report
Footnotes.
1. MA = Monthly Average; WA = Weekly Average; DA = Daily Average; DM = Daily Maximum.
2. TRC values < 50 µg/L are considered compliant.
The highest annual average effluent flow is 2.06 MGD or 41.2% of the permitted flow in calendar year
(CY) 2022.
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 1 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): NO
Name of Monitoring Coalition: NA
If applicable, summarize any instream data and what instream monitoring will beproposedfor this permit
action: The current permit requires instream monitoring for DO, Temperature and Conductivity under 15A
NCAC 02B .0508. The upstream location is at NC 1351 (Cavel Chub Lake Road), —0.2 miles above the
outfall. The downstream location is at NC 1322 (Edwin Robertson Road), —3.8 miles below the outfall.
Instream data were acquired from submitted DMRs from August 2018 through February 2023 for review.
The data were checked against applicable stream standards as well as for effluent impacts, the latter via
statistical testing of downstream averages against the upstream average of each parameter using t-test with
the level of significance (p-value) set at 0.05. The data are summarized in Table 2 and discussed below.
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Table 2. Instream Data Summary: averages with ranges in parentheses.
*Statistically significantly different from Upstream.
Parameter, units
Upstream
Downstream
Standard
DO, mg/L
Avg = 9.1
Avg = 9.1
5.0
(7.0-13.9)
(6.5-14.3)
Temperature, °C
Avg = 18.1
Avg = 18.4
32.0
(3.4-26.2)
(3.5-26.6)
Conductivity, µmhos/cm
Avg = 220
Avg = 231
(68-768)
(59-519)
Dissolved Oxygen (DO) — DO is in the permit as a parameter of concern for aquatic life. Summer minima
of both stations were all above the stream standard of 5.0 mg/L. No statistically significant differences were
found between the upstream and downstream stations. Concurrent effluent average DO is similar with lower
summer minima, and thus may be affecting the instream DO.
Temperature — Temperature is in the permit as a parameter of concern for aquatic life. Summer maxima at
both stations were below the 32°C standard for lower piedmont and coastal plain waters. No statistically
significant differences were found between the upstream and downstream stations; no upstream to
downstream increases were greater than the 2.8°C standard. Concurrent effluent temperatures appear
higher, with substantially higher winter minima.
Conductivity — Conductivity is in the permit as an indicator of industrial sources. The Town has an active
pretreatment program with two SIUs, a parts manufacturer and a textile industry. The downstream
Conductivity was found to be higher than upstream on average (p < 0.05). Effluent Conductivity monitoring
has been added to compare with instream values.
Fecal Coliform instream monitoring is not in the permit, nor is there any history of this parameter being
required for instream monitoring in any past permit since 1997. Division guidance for instream monitoring
allows Fecal Coliform to be removed from instream monitoring unless the receiving water is either Class
B or is impaired for fecal coliform. The receiving stream is Class C and is not impaired for fecal coliform;
therefore, it is not required and was not added to the permit.
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): From March 2018 through
February 2023 (past 5 years) no limit violations were reported.
Summarize the compliance record with aquatic toxicity test limits and any second species test results (past
5 years): The facility passed 17 of 17 quarterly chronic toxicity tests, as well as all 4 second species chronic
toxicity tests, sampled in June 2019 and March, September and December 2020.
Summarize the results from the most recent compliance inspection: The most recent facility inspection,
conducted on 02/15/2022, did not report any compliance issues. The most recent pretreatment inspection
was on 05/31/2022, also not reporting any compliance issues.
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NC0021024
6. Water Quality -Based Effluent Limitations (WQBELs)
6.1. Dilution and Mixing Zones
In accordance with 15A NCAC 2B.0206, the following streamflows are used for dilution considerations
for development of WQBELs: 1 Q 10 streamflow (acute Aquatic Life); 7Q 10 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 15A NCAC 2B.0204(b): NA.
6.2. 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/L for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
If permit limits are more stringent than TBELs, describe how limits were developed: Monthly/weekly
average BOD limits of 16.0/24.0 mg/L summer and 20.0/30.0 mg/L winter are derived from a wasteload
allocation (WLA) conducted in 1994.
6.3. 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/L (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 µg/L) and capped at 28 µg/L (acute impacts). Due to analytical issues, all TRC values
reported below 50 µg/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's Ammonia limits were 5.0115.0 mg/L monthly/weekly average in summer and 13.0/35.0 mg/L
monthly/weekly average in winter, originally set based on a WLA run in 1994 to protect the DO water
quality standard. In the 2013 permit renewal, Ammonia limits were updated to 1.0/3.0 mg/L summer and
1.8/5.4 mg/L winter with a compliance schedule to allow the Permittee time to make updates to the plant.
Since the 2013 permit issuance, the Ammonia compliance schedule has been extended multiple times, most
recently in 2021 to expire on November 30, 2021. In the permit renewal application, the City has requested
another extension, through December 31, 2022. However, since the expiration date has passed without
extension, the updated limits became effective December 1, 2021. A Wasteload Allocation (WLA) was
calculated for protection against Ammonia toxicity using the WWTPs design flow of 5.0 MGD and the
receiving stream's 7Q 10 of 0.0 cfs summer and winter. Resulting allowable concentrations as protective as
the current limits. The earlier limits were removed from the permit.
After the draft permit was sent to public notice for a 30-day comment period, comments were received from
the City, requesting reinstatement and extension of the ammonia compliance schedule, and requesting site -
specific limits be applied using the 70th percentile of input data. The facility is consistently meeting the
current limits, thus no need to reinstate or extend the expired compliance schedule. Site -specific allowable
concentrations were calculated using partially available and default data, with the former using the standard
901h percentiles, with results similar to but not necessarily less stringent than the current limits. Therefore,
no changes were made. See the attached Fact Sheet Addendum for details.
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NC0021024
The current permit TRC limit is 17 µg/L. The WLA used for Ammonia also produced an allowable TRC
concentration of 17 µg/L. No changes were made.
6.4. 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.
Because the receiving stream has a 7Q10 of 0.0 cfs, only effluent hardness sampling is required in the
current permit. Average effluent hardness = 47.6 mg/L; the effluent data are used in the RPA.
A reasonable potential analysis was conducted on effluent toxicant data collected between August 2018
through February 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: Copper: MA = 13.67 µg/L; DM = 19.23 µg/L.
• 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.
• 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: All
remaining parameters analyzed.
• POTW Effluent Pollutant Scan Review: Three effluent pollutant scans 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.
Only Chloroform and Chlorodibromomethane were detected. No detections were reported among
the remaining parameters analyzed.
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.
6.5. 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.
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NC0021024
Describe proposed toxicity test requirement: This is a Major POTW with a chronic WET limit at 90%
effluent and monitoring at a quarterly frequency, required under 40 CFR 1220)(5). No changes were made.
6.6. Mercury Statewide TMDL Evaluation
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/L) 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/L) and/or if any individual value exceeds a TBEL value of 47 ng/L.
The current permit requires a Mercury Minimization Plan to be maintained. Data are summarized below.
Table 3. Mercury Effluent Data Summary.
2018
2019
2020
2021
2022
# of Samples
1
4
3
4
4
Annual Average Conc. ng/L
8.4
3.6
3.2
2.1
1.7
Maximum Conc., ng/L
8.35
4.65
3.99
3.57
2.48
TBEL, ng/L
47
WQBEL, ng/L
12.0
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, no limits are
required. Since the facility is > 2 MGD and reported quantifiable levels of mercury (> 1 ng/L), the mercury
minimization plan (MMP) special condition is needed and is reworded toward its maintenance.
6.7. Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation within
this permit: The receiving stream currently has no TMDLs of Nutrient Management Strategy. The current
permit has monthly monitoring requirements for Total Nitrogen (TN) and Total Phosphorus (TP). Monthly
reporting of TN components Total Kjeldahl Nitrogen (TKN) and Nitrite -Nitrate (NO2+NO3) were added to
the permit to better understand nitrogen content of the effluent.
6.8. Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: The current permit has Oil
& Grease (O&G) requirements of a 30.0 mg/L monthly average limit with monthly monitoring, based on
BPJ. The limit was first added to the permit in 2002 with a weekly monitoring requirement, then monitoring
was reduced in the 2013 permit after comments by the EPA who questioned O&G limits in permits for
POTWs. O&G is a parameter of concern in the pretreatment program, based in part on its regulation in the
Industrial User Permits for the SIU Eaton Corporation, which has O&G limits. Based on review of the data
and that it is being tracked through the pretreatment program, O&G limits and monitoring were removed
from the permit.
A request for a Chemical Addendum was sent to the ORC after review of the permit application found it
lacking. The ORC responded: "At this time the City of Roxboro has not sampled for and does not have
information/analysis results for any additional pollutants (in particular emerging compounds 1,4-Dioxane
and PFAS chemicals)." The facility's discharge lies —10.6 miles upstream of the Virginia state line with no
water supply waters in between. Neither of the facility's SIUs belong to a category suspected of a source
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NC0021024
for 1,4-Dioxane, so no monitoring for this parameter will be added to the permit. Because of the general
pervasiveness of PFAS, monitoring has been added to the permit with a delayed implementation (see
Monitoring Requirements section below).
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 15A
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/L
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. Review of BOD and TSS data
found a total of 26 occurrences below 85% BOD removal and 38 occurrences below 85% TSS removal.
Occurrences were due to a combination of relatively low influent and/or high effluent values. Overall BOD
and TSS removal was greater than 85%.
If NO, provide a justification (e.g., waste stabilization pond). NA
8. Antidegradation Review (New/Expanding Discharge)
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 213.0201. Each applicant for a new/expanding NPDES permit must
document an effort to consider non -discharge alternatives per 15A NCAC 2H.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.
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NC0021024
If YES, confirm that antibacksliding provisions are not violated: NA.
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.
The current permit has reduced monitoring requirements at 2/week for BOD, Ammonia and Fecal Coliform
from a renewal in 2018. The City requested reduced monitoring frequencies for BOD, TSS, Ammonia and
Fecal Coliform based on Division Guidance for reduced monitoring frequencies for exceptionally
performing facilities (DWQ 2012) with justification on 5/8/2023. Effluent data from the past three years
(February 2020 — January 2023) were evaluated and found all applicable target parameters, including
Ammonia using the current limits, to meet the criteria. Monitoring for BOD, TSS, Ammonia and Fecal
Coliform is maintained at 2/week.
To identify PFAS contamination in waters throughout the state, monitoring requirements are to be
implemented in permits. Monitoring of PFAS chemicals has been added to the permit at a quarterly
frequency due to the pervasive nature of the chemical group and following guidance by EPA (memo,
12/5/2022). Since an EPA -approved method for sampling and analyzing PFAS in wastewater is not
currently available, the PFAS sampling requirement in the Permit includes a delayed implementation of
this requirement until the first full calendar quarter beginning 6 months after EPA has a final wastewater
method in 40 CFR 136 published in the Federal Register. This date may be extended upon request and if
there are no NC -certified labs.
For instream monitoring, refer to Section 4.
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. Effective December 21, 2020, NPDES regulated facilities will be required to submit
additional NPDES reports electronically. This permit contains the requirements for electronic reporting,
consistent with Federal requirements.
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12. Summary of Proposed Permitting Actions
Table 4. Current Permit Conditions and Proposed Changes 1,2
Parameter
Current Permit
Proposed Change
Basis for Condition/Change
Flow
5.0 MGD
No change
15A NCAC 213.0505
Summer:
MA = 16.0 mg/L
WQBEL. QUAL2E model
WA = 24.0 mg/L
No change in limits or
performed in September 2007.
BOD5
Winter:
MA = 20 mg/L
monitoring frequency
Effluent data meet criteria for
WA = 30 mg/L
reduced monitoring frequency.
Monitor 2/week
TBEL. Secondary treatment
MA = 30 mg/L
No change in limits or
standards/40 CFR 133 / 15A NCAC
TSS
WA = 45 mg/L
monitoring frequency
2B .0406.
Monitor 2/week
Effluent data meet criteria for
reduced monitoring frequency.
Interim Limits
Summer:
MA = 5.0 mg/L
WA = 15.0 mg/L
Winter:
MA = 13.0 mg/L
WQBEL. WLA-based for protection
WA = 35.0 mg/L
Remove Interim Limits
against ammonia toxicity. Interim
Monitor 2/week
limits removed based on expiration
NH3-N
Final Limits
Reduce monitoring to
of compliance schedule on
Summer
2/week.
November 30, 2021. Effluent data
MA 1.0 mg/L
meet criteria for reduced monitoring
WA = 3.0 mg/L
frequency.
Winter
MA = 1.8 mg/L
WA = 5.4 mg/L
Monitor daily
MA = 200 /100 mL
WQBEL. State WQ standard, 15A
Fecal Coliform
WA = 400 A 00 mL
No change in limits or
NCAC 213.0200.
Monitor 2/week
monitoring frequency
Effluent data meet criteria for
reduced monitoring frequency.
Total Residual
DM — 17 µg/L
No change
WQBEL. State WQ standard, 15A
Chlorine (TRC)
NCAC 213.0200.
> 5 mg/L
WQBEL. State WQ standard, 15A
DO
No change
NCAC 213.0200.
Monitor Daily
Temperature
Monitor daily
No change
State reporting requirements, 15A
NCAC 2B .0508.
pH
6 — 9 SU
No change
WQBEL. State WQ standard, 15A
Monitor daily
NCAC 213 .0200.
Page 11 of 14

NC0021024
Parameter
Current Permit
Proposed Change
Basis for Condition/Change
State reporting requirements, 15A
Instream monitoring
NCAC 2B .0508. Facility has a
Conductivity
only
Add weekly effluent
pretreatment program; increased
3/week Jun — Sep
monitoring
concentrations found downstream.
1/week Oct — May
Effluent monitoring frequency to
better match instream frequency.
TKN
No requirement
Add monthly monitoring
To calculate Total Nitrogen
NO2+NO3
No requirement
Add monthly monitoring
To calculate Total Nitrogen
Total Nitrogen
Monitor monthly
No change
State reporting requirements, 15A
(TN)
NCAC 2B .0508.
Total Phosphorus
Monitor monthly
No change
State reporting requirements, 15A
(TP)
NCAC 2B .0508.
BPJ. Effluent data average 5.1
Oil &Grease
MA = 30.0 mg/L
Remove from permit
mg/L, < 50% of previous limit;
Monitor monthly
parameter is monitored through
pretreatment program.
Required to assess dissolved metal
Total Hardness
Monitor quarterly
No change
limitations (instream monitoring not
required as 7Q10 = 0 cfs).
MA = 13.7 µg/L
DM = 19.2 µg/L
No change in
MA = 14.8 µg/L
monitoring.
WQBEL. Reasonable Potential to
Total Copper
DM = 21.0 µg/L
Add note that Permittee
exceed stream water quality standard
Monitor monthly
can request re-
(RP) found with updated Hardness
evaluation after 24
data.
months data collection
from monthly to
quarterly.
No RP found; maximum predicted
Total Nickel
Monitor quarterly
Remove from permit
effluent value < 50% of the
allowable concentration.
No RP found; maximum predicted
Total Zinc
Monitor quarterly
Remove from permit
effluent value < 50% of the
allowable concentration.
Mercury
Reword toward MMP
Minimization Plan
Special condition
maintenance
Statewide Mercury TMDL
(MMP)
PFAS
No requirement
Add quarterly
monitoring with delayed
EPA recommendations (guidance
implementation
memo, 12/5/2022).
Chronic limits 90%
WQBEL. No toxics in toxic
Toxicity Test
effluent using
C effluent
usingiodaphnia dubia.
No change
amounts. 15A NCAC 2B.0200 and
Monitor quarterly
15A NCAC 2B.0500.
Page 12 of 14

NC0021024
Parameter
Current Permit
Proposed Change
Basis for Condition/Change
Effluent Pollutant
Three times per
Update sampling years:
40 CFR 122
Scan
permit cycle
2025, 2026, 2027.
Electronic
Special Condition
Update language
In accordance with EPA Electronic
Reporting
Reporting Rule 2015.
Footnote: 1. MGD = Million gallons per day; MA = Monthly Average; WA = Weekly Average; DM = Daily Max.
13. Public Notice Schedule
Permit to Public Notice: 05/25/2023, 08/17/2023.
Per 15A NCAC 21-1.0109 & .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-day 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
Gary Perlmutter at [phone] or via email at [e-mail].
15. Fact Sheet Addendum (if applicable)
Were there any changes made since the Draft Permit was public noticed (Yes/No): Yes. With public notice,
copies of the draft permit were sent to the City, USEPA, various members of the Division and the Virginia
DEQ since the receiving stream crosses state lines. Comments were received only from the City, on
6/21/2023, with several requests. A full list of comments and Division responses are provided in the
attached Fact Sheet Addendum.
If Yes, list changes and their basis below:
• Effluent conductivity monitoring is reduced from daily to weekly to better match instream
monitoring.
• A footnote was added to the effluent requirements sheet stating that the Permittee may request a
re-evaluation of copper limits after 24 months of sampling based on evaluation of effluent data
showing no reasonable potential to exceed allowable concentrations from the previous two years.
• The annual mercury limit was removed as the limit was based on data older than 4.5 yrs and outside
the review period.
Based on these changes, primarily the removal of the annual Mercury limit, the draft was sent for a second
public comment period. No comments on the second draft were received. Only one change was made to
the final permit:
• The PFAS condition was revised to reflect the EPA 4"' Daft Method 1633, released in July, 2023.
Page 13 of 14

NC0021024
16. Fact Sheet Attachments (if applicable)
• NPDES Pretreatment POC form
• Monitoring report violations
• WET Summary sheet, p. 89
• Compliance inspection report
• NH3/TRC WLA calculation form
• RPA Spreadsheet Summary
• Dissolved Metals Fact Sheet Memo
• Mercury TMDL Evaluation
• Correspondence with ORC re: requested information
• Monitoring reduction request from ORC
• Monitoring Reduction spreadsheet
• Comments to the first draft permit by the City of Roxboro
• Fact Sheet Addendum
Page 14 of 14

A 13 C D E F I G I H I J K L M N O 1 P
NPDES/PT POC Review Form Version: 2022.06.22
2
1. Facility's General Information
3
Data of (draft) Review
4/6/2023
c. POC review due to:
e. Contact Information
4
Data cf (final) Review
Municipal NPDES rarawal
❑
Regicnal Office (RO) Raleigh
5
NPDES Permit Writer (pw)
Gary Perlmutter
HWA-AT/LTMP Review
❑
RO PT Staff Chang Zhang RO NPDES Staff Scott Vincent
6
Permitlee-Facility Name
City of Roxboro - Roxboro W WTP
New Industries
❑
Facility PT Staff, email Crystal Shotwell <crbowes(Dcitvofroxboro.ci
7
NPDES Permit Number
NCO021024
WWTP e>gansion
❑
f. Receiving Stream
8
NPDES Permit Effective Date
7/1/2014
Stream reclasedadjustment
❑
Outfall
9
Chemical Addendum Submittal Data
Outfall relmationladjustment
❑
Receiving Stream:
Madowe Creek
CA, cfs:
4
10
NPDES Permit Public Notice Date
7Q10 update
❑
Stream Class
C
7Q10I cts:
0
11
eDMR data evaluated from:
to
Other POC review trigger, explain:
Oufall Lat.
36.26.41 N
Ouffall Long.
78.58.47 Wthe
12
3
a. W WTP Capacity Summary
Outfall 11
Current Permitted Flow, mgd
5.0 Designed d Fes'' 5.0
Receiving Stream:
OA, cfs:
14
Permitted SIU Flow, mgd
0.20
d. IU Summary
Stream Class
7Q10. cfs:
771F
15
b. PT Docs. Summary
#IUs
Oufall Let.
Ouffall Long.
16
IWS approval date
11/18/2019
#SIUs
2
Is there a PWS downstream of the Facility's Outfalls? ❑ YES NO
17
3 USTMP approval date:
10/30/2017
# Clue
0
Comments:
18
19
.E
d H W A approval data
m
0
10/29/2018
If NSCIUs
The outiall lies about 10.25 miles upstream or the Virginia state line.
If Us w/Local
Permits or Other
T es
20
Z 2. Industrial Users' Information.
21
#
Industrial User (IU) Name
IU Activity
IU Non Conventional Pdhtans 8 Toxic Pollutant IUP Effective Date
22
1
Eaton Corporation
Manufacturing
NH3-N, Cu, CN, Ni, Zn, Oil 8 Grease 7 112022
23
2
Spuntech Industries, Inc.
Textiles
NH3-N, Cu, CN, Sit, Zn 1:4/2022
24
3
25
4
26
s
ir
31
comment:
32
3. Status of Pretreatment Program (check all that apply)
33
Status of Pretreatment Pro ram check all that appl
34
❑
1) facility has no SIUs, does have Division approved Pretreatment Program that is INACTIVE
35
❑
2) facility has no SIUs, does not have Division approved Pretreatment Program
36
❑
3) facility has SIUs and DWQ approved Pretreatment Program
37
❑
3a) Full Program with LTMP
38
❑
31b) Modified Program with STMP
39
❑
4) additional conditions regarding Pretreatment
attached
or listed
below
4D
5) facility's sludge is being land applied or composted
41
❑
6) facility's sludge is incinerated (add Beryllium and Mercury sampling according
to § 503.43)
42
43
❑
❑
7) facility's sludge is taken to a landfill, if yes which landfill:
8) other
44
45
46
Sludge Disposal Plan:
tjil"
47
Sludge Permit No: W00003417
Page 1 21024 POC Review Form

PW: Find L/STMP document, HWA spreadsheet, DMR, previous and new NPDES permit for next section.
a
�
Comment
N�
PQLs review
U
m
New
Previous
%
PQL from
Required PQL
Recomm.
Parameter of Concern
NPDES
NPDES
Required by
POC due to
POC due to
POTW
Removal
L/STMP
NPDES
L/STMP, ug/I
per NPDES
PQL, ug/I
POC Check List
POC
POC
EPA PT 1
Sludge 2
SIU 3
POC 4
Rate
Effluent Freq
Effluent Freq
permit
0
Flow
❑
❑
❑
❑
❑
BOD
Li
❑
❑
El2.0
0
TSS
El
F17
❑
❑
O
NH3
❑
❑
❑
❑
n
Arsenic
n
n
n
n
n
2.0
2.0
Footnotes:
(1) Always in the LTMP/STMP due to
EPA -PT requirement
(2) Only in LTMP/STMP R listed in sludge permit
(3) Only in LTMP/STMP while SIU still discharges to POTW
(4) Only in LTMP/STMP when pollutant is still of concern to POTW
(5) In LTMP/STMP, R sewage sludge is incinerated
Please use blue fort for the info updated by pw
Please use red font for POC that need to be addedlmodi ied In L/STMP
sampling
plan
Blue shaded cell (D60:H82): I Parameters usually included under that POC list
Facility Summary/background information/NPDES-PT regulatory action:
POC to be added/modified In USTMP:
ORC's comments on IU/POC:
POC submitted through Chemical
Addendum or Supplemental Chemical
Datasheet:
Additional pollutants added to USTMP due
to POTWs concerns:
NPDES pw's comments on IU/POC.
Page 2 21024 POC Review Form

MONITORING REPORT(MR) VIOLATIONS for:
Permit: NC21024 MRS Betweel 3 - 2018 and 4 - 2023 Region: %
Facility Name: % Param Nam(% County: %
Major Minor: %
Report Date: 04/10/22 Page 1 of 1
Violation Category:% Program Category: NPDES WW
Subbasin: % Violation Action:
PERMIT: FACILITY: COUNTY: REGION:
MONITORING VIOLATION UNIT OF CALCULATED %
REPORT LOCATION PARAMETER DATE FREQUENCY MEASURE LIMIT VALUE Over VIOLATION TYPE VIOLATION ACTION

Whole Effluent Toxicity Testing and Self Monitoring Summary
Roseboro WWTP
NCO026816/001
County:
Sampson
Ceri7dPF
Begin:
11/1/2017 chr lim: 52%
NonComp:
Single
J
F
M
A
M
2019
-
Pass
-
-
Pass
2020
-
Pass
-
-
Pass
2021
-
Pass
-
-
Pass
2022
-
Pass
-
-
Pass
2023
-
Pass
-
-
-
Roxboro Steam Electric Power Plant NC0003425/003
County:
Person
Fthd24PF
Begin:
8/1/2021 24hr ac p/f
lim: 90%f +
NonComp:
Single
J
F
M
A
M
2019
-
-
Pass
-
-
2019
-
-
>100
-
-
2020
-
-
-
>100
-
2020
-
-
Pass
-
-
2020
2021
-
-
Pass
-
-
2021
-
-
Pass
-
-
2021
2022
-
-
Pass
-
-
2022
2022
-
-
Pass
-
-
Roxboro WTP
NC0003042/001
County:
Person
Ceri7dPF
Begin:
4/1/2018 Chr Monit:
90%
NonComp:
J
F
M
A
M
2019
Pass
-
-
Pass
-
2020
Pass
-
-
Pass
-
2021
Fail
-
-
Pass
-
2022
Pass
-
-
Pass
-
2023
Pass
-
-
-
-
Roxboro WWTP NCO021024/001 County: Person
Ceri7dPF Begin: 11/1/2018 chr lim: 90% NonComp: Single
J F M A M
2019 - - Pass - -
2020 - - Pass>100(P) - -
2021 - - Pass - -
2022 - - Pass - -
2023 - - Pass - -
Region: FRO
Basin:
CPF19
Feb May Aug Nov
7Q10: 1.0
PF: 0.49
IWC:
52 Freq: Q
J
J
A
S
O
Pass
Pass
Pass
Pass
Region: RRO
Basin:
ROA05
Mar Jun Sep Dec
7Q10: Lake
PF: NA
IWC:
NA Freq: Q
J
J
A
S
O
Pass
-
-
Pass
-
Pass
-
-
Pass
-
Pass
Pass
-
-
Pass
-
Pass
-
-
Pass
-
H
Pass
-
-
Pass
-
H
Pass
-
-
Pass Pass
-
Region: RRO
Basin:
ROA05
Jan Apr Jul Oct
7Q10:
PF:
IWC:
Freq: Q
J
J
A
S
O
-
Pass
-
-
Pass
-
Pass
-
-
Pass
-
Fail
-
-
Pass
-
Pass
-
-
Fail
SOC JOC:
N
Pass
Pass
Pass
Pass
SOC JOC:
N
C
D
Pass
Pass
Pass
H
Pass
Pass
Pass
SOC JOC:
N D
Region: FRO Basin: ROA05 Mar Jun Sep Dec SOC JOC:
7Q10: 0.0 PF: 5.0 IWC: 100 Freq: Q
J J A S O N D
Pass >100(P) - - Pass - - Pass
Pass - - Pass - - Pass
Pass - - Pass - - Pass
Pass - - Pass - - Pass
Leeend: P= Fathead minnow (Pimohales oromelas). H=No Flow (facilitv is active). s = SDlit test between Certified Labs Page 89 of 112

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 NCO021024 I11 121 22/02/15 I17 18I � I 19 I s 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
I 72 I n, I 71 I 74 79 I I I I I I I80
701 I 71 I LL -1 I I
LJ
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)
10:OOAM 22/02/15
18/11/01
Roxboro WWTP
902 Cavel-Chub Lake Rd
Exit Time/Date
Permit Expiration Date
Roxboro NC 27573
01:OOPM 22/02/15
22/05/31
Name(s) of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s)
Other Facility Data
Derek Lynn Clayton/ORC/336-599-8232/
Name, Address of Responsible Official/Title/Phone and Fax Number
Contacted
Derek Lynn Clayton,PO Box 128 Roxboro NC 275730128//336-599-8232/
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 Goss DWR/RRO WQ/919-791-4200/
Molly Nicholson DWR/RRO WQ/919-791-4240/
Signature of Management Q A Reviewer Agency/Office/Phone and Fax Numbers Date
EPA Form 3560-3 (Rev 9-94) Previous editions are obsolete.
Page#

NPDES yr/mo/day Inspection Type
NCO021024 I11 12I 22/02/15 117 18 i c i
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
Page#

Permit: NCO021024
Inspection Date: 02/15/2022
Owner -Facility: Roxboro WWTP
Inspection Type: Compliance Evaluation
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:
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
❑
❑
❑
# Are there any special conditions for the permit?
❑
❑
■
❑
Is access to the plant site restricted to the general public?
0
❑
❑
❑
Is the inspector granted access to all areas for inspection?
0
❑
❑
❑
Comment:
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?
❑
❑
❑
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?
Page# 3

Permit: NC0021024 Owner -Facility:
Inspection Date: 02/15/2022 Inspection Type:
Roxboro WWTP
Compliance Evaluation
Record Keeping
Yes
No
NA
NE
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:
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?
M
❑
❑
❑
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:
Aerobic Digester
Yes
No
NA NE
Is the capacity adequate?
■
❑
❑
❑
Is the mixing adequate?
❑
❑
❑
■
Is the site free of excessive foaming in the tank?
0
❑
❑
❑
# Is the odor acceptable?
■
❑
❑
❑
# Is tankage available for properly waste sludge?
■
❑
❑
❑
Comment:
Drying Beds
Yes
No
NA
NE
Is there adequate drying bed space?
❑
❑
❑
Is the sludge distribution on drying beds appropriate?
❑
❑
❑
■
Are the drying beds free of vegetation?
❑
❑
❑
# Is the site free of dry sludge remaining in beds?
❑
❑
❑
Is the site free of stockpiled sludge?
❑
❑
❑
Is the filtrate from sludge drying beds returned to the front of the plant?
❑
❑
❑
■
# Is the sludge disposed of through county landfill?
❑
❑
❑
Page# 4

Permit: NC0021024
Inspection Date: 02/15/2022
Owner -Facility: Roxboro WWTP
Inspection Type: Compliance Evaluation
Drying Beds
Yes
No
NA
NE
# Is the sludge land applied?
❑
❑
❑
(Vacuum filters) Is polymer mixing adequate?
❑
❑
❑
Comment:
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?
0
❑
❑
❑
Is disposal of screening in compliance?
0
❑
❑
❑
Is the unit in good condition?
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?
■
❑
❑
❑
# Is disposal of grit in compliance?
0
❑
❑
❑
Comment:
Equalization Basins
Yes
No
NA
NE
Is the basin aerated?
❑
❑
0
❑
Is the basin free of bypass lines or structures to the natural environment?
❑
❑
0
❑
Is the basin free of excessive grease?
❑
❑
■
❑
Are all pumps present?
❑
❑
■
❑
Are all pumps operable?
❑
❑
0
❑
Are float controls operable?
❑
❑
0
❑
Are audible and visual alarms operable?
❑
❑
0
❑
# Is basin size/volume adequate?
❑
❑
■
❑
Comment:
Page# 5

Permit: NCO021024
Inspection Date: 02/15/2022
Equalization Basins
Owner -Facility: Roxboro WWTP
Inspection Type: Compliance Evaluation
Secondary Clarifier
Is the clarifier free of black and odorous wastewater?
Is the site free of excessive buildup of solids in center well of circular clarifier?
Are weirs level?
Is the site free of weir blockage?
Is the site free of evidence of short-circuiting?
Is scum removal adequate?
Is the site free of excessive floating sludge?
Is the drive unit operational?
Is the return rate acceptable (low turbulence)?
Is the overflow clear of excessive solids/pin floc?
Is the sludge blanket level acceptable? (Approximately'/4 of the sidewall depth)
Comment:
Aeration Basins
Mode of operation
Type of aeration system
Is the basin free of dead spots?
Are surface aerators and mixers operational?
Are the diffusers operational?
Is the foam the proper color for the treatment process?
Does the foam cover less than 25% of the basin's surface?
Is the DO level acceptable?
Is the DO level acceptable?(1.0 to 3.0 mg/1)
Comment:
Standby Power
Is automatically activated standby power available?
Is the generator tested by interrupting primary power source?
Is the generator tested under load?
Was generator tested & operational during the inspection?
Do the generator(s) have adequate capacity to operate the entire wastewater site?
Yes No NA NE
Yes
No
NA
NE
■
❑
❑
❑
■
❑
❑
❑
■
❑
❑
❑
■
❑
❑
❑
■
❑
❑
❑
■
❑
❑
❑
■
❑
❑
❑
■
❑
❑
❑
❑
❑
❑
■
■
❑
❑
❑
■
❑
❑
❑
Yes No NA NE
■ ❑ ❑ ❑
■ ❑ ❑ ❑
❑ ❑ ❑ ■
■ ❑ ❑ ❑
■ ❑ ❑ ❑
❑ ❑ ❑ ■
❑ ❑ ❑ ■
Yes No NA NE
■ ❑ ❑ ❑
■ ❑ ❑ ❑
■ ❑ ❑ ❑
■ ❑ ❑ ❑
■ ❑ ❑ ❑
Page# 6

Permit: NCO021024 Owner -Facility: Roxboro WWTP
Inspection Date: 02/15/2022 Inspection Type: Compliance Evaluation
Standby Power Yes
No
NA
NE
Is there an emergency agreement with a fuel vendor for extended run on back-up 0
❑
❑
❑
power?
Is the generator fuel level monitored? 0
❑
❑
❑
Comment:
Effluent Sampling
Yes
No
NA
NE
Is composite sampling flow proportional?
0
❑
❑
❑
Is sample collected below all treatment units?
0
❑
❑
❑
Is proper volume collected?
■
❑
❑
❑
Is the tubing clean?
❑
❑
0
❑
# Is proper temperature set for sample storage (kept at less than or equal to 6.0
■
❑
❑
❑
degrees Celsius)?
Is the facility sampling performed as required by the permit (frequency, sampling type
■
❑
❑
❑
representative)?
Comment:
Influent Sampling
Yes
No
NA
NE
# Is composite sampling flow proportional?
0
❑
❑
❑
Is sample collected above side streams?
0
❑
❑
❑
Is proper volume collected?
0
❑
❑
❑
Is the tubing clean?
❑
❑
0
❑
# Is proper temperature set for sample storage (kept at less than or equal to 6.0
■
❑
❑
❑
degrees Celsius)?
Is sampling performed according to the permit?
0
❑
❑
❑
Comment:
Disinfection -Liquid
Yes
No
NA NE
Is there adequate reserve supply of disinfectant?
❑
❑
❑
■
(Sodium Hypochlorite) Is pump feed system operational?
0
❑
❑
❑
Is bulk storage tank containment area adequate? (free of leaks/open drains)
❑
❑
❑
Is the level of chlorine residual acceptable?
0
❑
❑
❑
Is the contact chamber free of growth, or sludge buildup?
■
❑
❑
❑
Is there chlorine residual prior to de -chlorination?
❑
❑
❑
Comment:
Page# 7

Permit: NCO021024 Owner -Facility: Roxboro WWTP
Inspection Date: 02/15/2022 Inspection Type: Compliance Evaluation
Laboratory
Yes
No
NA
NE
Are field parameters performed by certified personnel or laboratory?
■
❑
❑
❑
Are all other parameters(excluding field parameters) performed by a certified lab?
■
❑
❑
❑
# Is the facility using a contract lab?
■
❑
❑
❑
# Is proper temperature set for sample storage (kept at less than or equal to 6.0
■
❑
❑
❑
degrees Celsius)?
Incubator (Fecal Coliform) set to 44.5 degrees Celsius+/- 0.2 degrees?
■
❑
❑
❑
Incubator (BOD) set to 20.0 degrees Celsius +/- 1.0 degrees?
❑
❑
■
❑
Comment:
De -chlorination
Yes No
NA
NE
Type of system ?
Liquid
Is the feed ratio proportional to chlorine amount (1 to 1)?
❑ ❑
❑
■
Is storage appropriate for cylinders?
❑ ❑
❑
■
# Is de -chlorination substance stored away from chlorine containers?
❑ ❑
❑
■
Comment:
Are the tablets the proper size and type? ❑ ❑ ■ ❑
Are tablet de -chlorinators operational? ❑ ❑ ■ ❑
Number of tubes in use?
Comment:
Page# 8

NH3/TRC WLA Calculations
Roxboro WWTP
Permit No. NC0021024
Prepared By: Gary Perlmutter
Enter Design Flow (MGD): 5
Enter s7Q10 (cfs): 0
Enter w7Q10 (cfs): 0
Total Residual Chlorine (TRC)
Ammonia (Summer)
Daily Maximum Limit (ug/1)
Monthly Average Limit (mg NH3-N/1)
s7Q10 (CFS) 0
s7Q10 (CFS)
0
DESIGN FLOW (MGD) 5
DESIGN FLOW (MGD)
5
DESIGN FLOW (CFS) 7.75
DESIGN FLOW (CFS)
7.75
STREAM STD (UG/L) 17.0
STREAM STD (MG/L)
1.0
Upstream Bkgd (ug/1) 0
Upstream Bkgd (mg/1)
0.22
IWC (%) 100.00
IWC (%)
100.00
Allowable Conc. (ug/1) 17
Allowable Conc. (mg/1)
1.0
Ammonia (Winter)
Monthly Average Limit (mg NH3-N/1)
Fecal Coliform
w7Q10 (CFS)
0
Monthly Average Limit: 200/100ml
DESIGN FLOW (MGD)
5
(If DF >331; Monitor)
DESIGN FLOW (CFS)
7.75
(If DF<331; Limit)
STREAM STD (MG/L)
1.8
Dilution Factor (DF) 1.00
Upstream Bkgd (mg/1)
0.22
IWC (%)
100.00
Allowable Conc. (mg/1)
1.8
Total Residual Chlorine
1. Cap Daily Max limit at 28 ug/I 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); capped at 35 mg/I
3. Monthly Avg limit x 5 = Daily Max limit (Non-Munis);
capped at 35 mg/I
Fecal Coliform
1. Monthly Avg limit x 2 = 400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non -Muni)

Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM DATA POINTS = 58
REQUIRED DATA ENTRY
Table 1. Proiect Information
Facility Name
WWTP/WTP Class
NPDES Permit
Outfall
Flow, Qw (MGD)
Receiving Stream
HUC Number
Stream Class
❑ CHECK IF HQW OR ORW WQS
Roxboro WWTP
Grade IV
NCO021024
001
5.000
Marlowe Creek
03010104
C
❑ Apply WS Hardness WQC
7Q10s (cfs)
7Q10w (cfs)
30Q2 (cfs)
QA (cfs)
1Q10s (cfs)
0.00
0.00
0.00
4.00
0.00
_Effluent Hardness
Upstream Hardness
Combined Hardness Chronic
Combined Hardness Acute
47.65 mg/L (Avg)
NO UPSTREAM HARDNESS DATA
I _ _ _ _ _ _ _ 47.65 mg/L
I 47.65 mg/L
Permittee-submitted DMRs and PPAs.
Data Source(s)
❑ CHECK TO APPLY MODEL
Par01
Par02
Par03
Par04
Par05
Par06111111
Par07
Par08
Par09
Par10
Par11
Par12
Par13
Par14
Par15
Par16
Par17
Parts
Par19
Par20
Par21
Par22
Par23
Par24
Table 2. Parameters of Concern
Name w4s Type Chronic ModIer Acute PQL Units
Arsenic
Aquactic Life
C
150
FW
340
ug/L
Arsenic
Human Health
Water Supply
C
10
HH/WS
N/A
ug/L
Beryllium
Aquatic Life
NC
6.5
FW
65
ug/L
Cadmium
Aquatic Life
NC
0.9605
FW
5.6880
ug/L
Chlorides
Aquatic Life
NC
230
FW
Chlorinated Phenolic Compounds
Water Supply
NC
1
A
ug/L
Total Phenolic Compounds
Aquatic Life
NC
300
A
ug/L
Chromium III
Aquatic Life
NC
199.6661
FW
1534.9549
ug/L
Chromium VI
Aquatic Life
NC
11
FW
16
pg/L
Chromium, Total
Aquatic Life
NC
N/A
FW
N/A
pg/L
Copper
Aquatic Life
NC
13.6745
FW
19.2285
ug/L
Cyanide
Aquatic Life
NC
5
FW
22
10
ug/L
Fluoride
Aquatic Life
NC
1,800
FW
ug/L
Lead
Aquatic Life
NC
6.0532
FW
155.3350
ug/L
Mercury
Aquatic Life
NC
12
FW
0.5
ng/L
Molybdenum
Human Health
NC
2000
HH
ug/L
Nickel
Aquatic Life
NC
64.2509
FW
578.4768
pg/L
Nickel
Water Supply
NC
25.0000
WS
N/A
pg/L
Selenium
Aquatic Life
NC
5
FW
56
ug/L
Silver
Aquatic Life
NC
0.06
FW
0.8988
ug/L
Zinc
Aquatic Life
NC
218.8901
FW
217.1141
ug/L
Chlorodibromomethane
Human Health
C
21
HH
pg/L
Chloroform
Aquatic Life
NC
2000
1 FW
I
pg/L
21024 FW RPA 2023, input
5/24/2023

H1
1
2
3
4
5
6
7
8
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
REASONABLE POTENTIAL ANALYSIS
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
8/7/2018
46
46
9/4/2018
44
44
9/11/2018
41.2
41.2
10/2/2018
48
48
11/6/2018
36
36
2/6/2019
52
52
6/4/2019
55.6
55.6
7/2/2019
52
52
8/6/2019
76
76
10/1/2019
72
72
1 /7/2020
44
44
5/5/2020
52
52
7/7/2020
48
48
9/22/2020
45.9
45.9
10/6/2020
48
48
1/5/2021
40
40
3/2/2021
49.1
49.1
4/6/2021
48
48
7/5/2021
40
40
10/5/2021
44
44
1/5/2022
36
36
2/1/2022
64
64
3/8/2022
40
40
4/5/2022
44
44
5/4/2022
44
44
6/7/2022
48
48
7/5/2022
44
44
10/4/2022
36
36
1/10/2023
44
44
Results
Std Dev.
9.4681
Mean
47.6483
C.V.
0.1987
n
29
10th Per value
39.20 mg/L
Average Value
47.65 mg/L
Max. Value
76.00 mg/L
Date Data
BDL=1/2DL Results
1
Std Dev.
NO DATA
2
Mean
NO DATA
3
C.V.
NO DATA
4
n
0
5
10th Per value
NO DATA mg/L
6
Average ValueVESS DATA mg/L
7
Max. Value
NO DATA mg/L
8
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
21024 FW RPA 2023, data
-2- 5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par01 & Par02
Date Data
1 8/13/2018 <
2 9/11/2018 <
3 11 /30/2018 <
4 2/6/2019 <
5 7/10/2019 <
6 1 /7/2020 <
7 3/3/2020 <
8 5/18/2020 <
9 9/22/2020 <
10 10/6/2020 <
11 3/2/2021 <
12 6/7/2021 <
13 9/14/2021 <
14 12/9/2021 <
15 3/8/2022 <
16 6/7/2022 <
17 9/13/2022 <
18 12/6/2022 <
19
20
21
22
23
24
25
26
27
28
29
3
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
Arsenic
BDL=1/2DL
Results
2 1
Std Dev.
2 1
Mean
2 1
C.V.
2 1
n
2 1
2 1
Mult Factor =
2 1
Max. Value
2 1
Max. Fred Cw
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
Use "PASTE SPECIAL Par03
Values" then "COPY"
. Maximum data
points = 58
1.0000
0.0000
18
1.00
1.0 ug/L
1.0 ug/L
Date Data
1 3/2/2021 <
2 6/7/2022 <
3 6/1/2019 <
4 9/1/2020 <
5
6
7
8
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
Use "PASTE SPECIAL
Beryllium
Values" then "COPY"
. Maximum data
points = 58
BDL=1/2DL
Results
5
2.5
Std Dev.
1.2990
5
2.5
Mean
1.3750
0.5
0.25
C.V. (default)
0.6000
0.5
0.25
n
4
■
Mult Factor =
2.59
Max. Value
2.50 ug/L
Max. Fred Cw
6.48 ug/L
-3-
21024 FW RPA 2023, data
5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par04
Cadmium
Date
Data
BDL=1/2DL
Results
1
8/13/2018
<
0.15
0.075
Std Dev.
2
9/11/2018
<
0.15
0.075
Mean
3
11/30/2018
<
0.15
0.075
C.V.
4
2/6/2019
0.15
0.15
n
5
7/10/2019
<
0.15
0.075
6
10/1/2019
<
0.15
0.075
Mult Factor =
7
1/7/2020
<
0.15
0.075
Max. Value
8
3/3/2020
<
0.15
0.075
Max. Fred Cw
9
5/18/2020
<
0.15
0.075
10
9/22/2020
<
0.15
0.075
11
10/6/2020
<
0.15
0.075
12
6/7/2021
<
0.15
0.075
13
9/14/2021
<
0.15
0.075
14
12/9/2021
<
0.15
0.075
15
3/8/2022
<
0.15
0.075
16
6/7/2022
<
0.15
0.075
17
9/13/2022
<
0.15
0.075
18
12/6/2022
<
0.15
0.075
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
Use "PASTE SPECIAL Pdr05
Values" then "COPY"
. Maximum data
points = 58
0.0792
0.2233
18
1.15
0.150 ug/L
0.173 ug/L
1
2
3
4
5
6
7
8
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
Chlorides
Date Data BDL=1/2DL Results
Std Dev.
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Fred Cw
Use "PASTE SPECIAL -
Values" then "COPY" .
Maximum data points =
58
NO DATA
NO DATA
0
N/A
N/A mg/L
N/A mg/L
-4-
21024 FW RPA 2023, data
5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par06
Chlorinated Phenolic Compounds
Use "PASTE SPECIAL
valves" imthenum •copydata
. Max
Par07
Total Phenolic Compounds
points = 58
Date Data BDL=1/2DL Results
Date
Data BDL=1/2DL Results
1
Std Dev.
NO DATA
1 6/7/2022
12 12 Std Dev.
2
Mean
NO DATA
2
Mean
3
C.V.
NO DATA
3
C.V. (default)
4
n
0
4
n
5
5
6
Mult Factor =
N/A
6
Mult Factor =
7
Max. Value
N/A ug/L
7
Max. Value
8
Max. Fred Cw
N/A ug/L
8
Max. Fred Cw
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
Use "PASTE SPECIAL
Values" then "COPY"
. Maximum data
points = 58
12.0000
0.6000
1
6.20
12.0 ug/L
74.4 ug/L
21024 FW RPA 2023, data
-5- 5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par08
Chromium III
Date
Data BDL=1/2DL Results
1
Std Dev.
2
Mean
3
C.V.
4
n
5
6
Mult Factor =
7
Max. Value
8
Max. Fred Cw
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
Pdr09
Use "PASTE SPECIAL
Values" then "COPY"
Chromium VI
. Maximum data
points = 58
Date
Data BDL=1/2DL Results
NO DATA
1
Std Dev.
NO DATA
2
Mean
NO DATA
3
C.V.
0
4
n
5
N/A
6
Mult Factor =
N/A Ng/L
7
Max. Value
N/A Ng/L
8
Max. Fred Cw
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
Use "PASTE SPECIAL
Values" then "COPY'
. Maximum data
points = 58
NO DATA
NO DATA
NO DATA
0
N/A
N/A Ng/L
N/A Ng/L
21024 FW RPA 2023, data
-6- 5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par10
Chromium, Total
Date
Data
BDL=1/2DL
Results
1
8/13/2018
3
3
Std Dev.
2
9/11/2018
3
3
Mean
3
11/30/2018
<
2
1
C.V.
4
2/6/2019
<
2
1
n
5
7/10/2019
<
2
1
6
10/1/2019
<
2
1
Mult Factor =
7
1/7/2020
<
2
1
Max. Value
8
3/3/2020
<
2
1
Max. Fred Cw
9
5/18/2020
<
2
1
10
9/22/2020
<
2
1
11
10/6/2020
<
2
1
12
3/2/2021
<
2
1
13
6/7/2021
<
2
1
14
9/14/2021
<
2
1
15
12/9/2021
<
2
1
16
3/8/2022
<
2
1
17
6/7/2022
<
2
1
18
9/13/2022
<
2
1
19
12/6/2022
<
2
1
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
Use "PASTE SPECIAL Pa11
Values" then "COPY"
. Maximum data
points = 58
1.2105
0.5209
19
1.34
3.0 Ng/L
4.0 Ng/L
Date Data
1 1 /7/2020
2 2/4/2020
3 3/3/2020
4 4/7/2020
5 5/5/2020
6 5/18/2020
7 6/3/2020
8 7/7/2020
9 8/4/2020
10 9/22/2020
11 10/6/2020
12 11/3/2020
13 12/1/2020
14 12/8/2020
15 12/10/2020
16 12/11 /2020
17 12/22/2020
18 12/29/2020
19 1/5/2021
20 2/3/2021
21 3/2/2021
22 4/6/2021
23 5/5/2021
24 6/7/2021
25 7/5/2021
26 8/3/2021
27 9/14/2021
28 10/5/2021
F11 /2/2021
12/9/2021
1/5/2022
32 2/1/2022
33 3/8/2022
34 4/5/2022
35 5/4/2022
36 6/7/2022
37 7/5/2022
38 8/2/2022
39 9/13/2022
40 10/4/2022
41 11/8/2022
42 12/6/2022
43 1/10/2023
44 2/7/2023
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Copper
BDL=1/2DL
Results
6
6
Std Dev.
9
9
Mean
8
8
C.V.
11
11
n
8
8
10
10
Mult Factor =
7
7
Max. Value
8
8
Max. Fred Cw
11
11
7
7
8
8
10
10
32
32
13
13
12
12
12
12
18
18
8
8
8
8
6
6
8
8
8
8
10
10
6
6
8
8
6
6
9
9
8
8
6
6
5.6
5.6
3.6
3.6
7
7
5
5
6
6
7
7
5
5
7
7
6
6
7
7
6
6
9
9
7
7
6
6
5
5
Use "PASTE SPECIAL
Values" then "COPY"
. Maximum data
points = 58
8.4818
0.5245
44
1.07
32.00 ug/L
34.24 ug/L
-7-
21024 FW RPA 2023, data
5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par12
Cyanide
Date
Data
BDL=1/2DL
Results
1
8/13/2018
<
5
5
Std Dev.
2
9/11/2018
<
5
5
Mean
3
11/30/2018
<
5
5
C.V.
4
2/6/2019
5
5
n
5
7/10/2019
<
5
5
6
3/3/2020
<
5
5
Mult Factor =
7
5/18/2020
<
5
5
Max. Value
8
9/22/2020
<
5
5
Max. Fred Cw
9
10/6/2020
<
5
5
10
3/2/2021
<
5
5
11
6/7/2021
<
5
5
12
9/14/2021
<
5
5
13
12/9/2021
<
5
5
14
3/8/2022
<
5
5
15
6/7/2022
<
5
5
16
9/13/2022
<
5
5
17
12/6/2022
<
5
5
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
Use "PASTE SPECIAL Par13
Values" then "COPY"
. Maximum data
points = 58
5.00
0.0000
17
1.00
5.0 ug/L
5.0 ug/L
1
2
3
4
5
6
7
8
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
Use "PASTE SPECIAL
Fluoride
values" then "COPY"
. Maximum data
points = 58
Date Data BDL=1/2DL Results
Std Dev.
NO DATA
Mean
NO DATA
C.V.
NO DATA
n
0
Mult Factor =
N/A
Max. Value
N/A ug/L
Max. Fred Cw
N/A ug/L
-8-
21024 FW RPA 2023, data
5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par14
Lead
Date
BDL=1/2DL
Results
1
8/13/2018
< 0.5
0.25
Std Dev.
2
9/11/2018
< 0.5
0.25
Mean
3
11/30/2018
< 0.5
0.25
C.V.
4
2/6/2019
< 0.5
0.25
n
5
7/10/2019
< 0.5
0.25
6
10/1/2019
< 0.5
0.25
Mult Factor =
7
1/7/2020
< 0.5
0.25
Max. Value
8
3/3/2020
< 0.5
0.25
Max. Fred Cw
9
5/18/2020
< 0.5
0.25
10
9/22/2020
< 0.5
0.25
11
10/6/2020
< 0.5
0.25
12
3/2/2021
0.6
0.6
13
6/7/2021
< 0.5
0.25
14
9/14/2021
< 0.5
0.25
15
12/9/2021
< 0.5
0.25
16
3/8/2022
< 0.5
0.25
17
6/7/2022
< 0.5
0.25
18
9/13/2022
< 0.5
0.25
19
12/6/2022
0.9
0.9
20
21
22
23
24
25
26
27
28
29
3
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
Use "PASTE SPECIAL Par15
Values" then "COPY"
. Maximum data
points = 58
0.3026
0.5465
19
1.35
0.900 ug/L
1.215 ug/L
1
2
3
4
5
6
7
8
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
Use "PASTE SPECIAL
Mercury
Values" then "COPY"
. Maximum data
points = 58
Date Data BDL=1/2DL Results
Std Dev.
NO DATA
Mean
NO DATA
C.V.
NO DATA
n
0
Mult Factor =
N/A
Max. Value
N/A ng/L
Max. Fred Cw
N/A ng/L
-9-
21024 FW RPA 2023, data
5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par16
Date Data
1 8/13/2018
2 9/11/2018
3 11 /30/2018 <
4 2/6/2019 <
5 7/10/2019
6 10/1/2019
7 1 /7/2020 <
8 3/3/2020 <
9 5/18/2020 <
10 9/22/2020 <
11 3/2/2021 <
12 6/7/2021 <
13 9/14/2021 <
14 12/9/2021 <
15 3/8/2022 <
16 6/7/2022 <
17 9/13/2022 <
18 12/6/2022 <
19
20
21
22
23
24
25
26
27
28
29
3
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
Molybdenum
BDL=1/2DL
Results
5 5
Std Dev.
12 12
Mean
2 1
C.V.
2 1
n
3 3
2 2
Mult Factor =
2 1
Max. Value
2 1
Max. Fred Cw
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
Use "PASTE SPECIAL Par17 & Pdr18
Values" then "COPY" Nickel
. Maximum data
points = 58
2.0000
1.3504
18
1.89
12.0 ug/L
22.7 ug/L
Use "PASTE SPECIAL
Values " then "COPY"
. Maximum data
points = 58
Date
Data
BDL=1/2DL
Results
1
8/13/2018
2.8
2.8
Std Dev.
0.9137
2
9/11/2018
3.3
3.3
Mean
1.9230
3
11/6/2018
1.7
1.7
C.V.
0.4751
4
11 /30/2018
2.2
2.2
n
37
5
2/6/2019
1.8
1.8
6
6/4/2019
2
2
Mult Factor =
1.11
7
7/2/2019
< 10
5
Max. Value
5.0 Ng/L
8
7/10/2019
2.2
2.2
Max. Fred Cw
5.6 Ng/L
9
10/1/2019
3.3
3.3
10
1 /7/2020
1.1
1.1
11
3/3/2020
1.4
1.4
12
3/3/2020
1.4
1.4
13
5/5/2020
1.8
1.8
14
5/18/2020
2.2
2.2
15
7/7/2020
1.9
1.9
16
9/22/2020
1.3
1.3
17
9/22/2020
1.3
1.3
18
10/6/2020
1.7
1.7
19
1 /5/2021
4
4
20
3/2/2021
1.2
1.2
21
4/6/2021
1.1
1.1
22
6/7/2021
2
2
23
7/5/2021
2.1
2.1
24
9/14/2021
2.1
2.1
25
10/5/2021
2.8
2.8
26
12/9/2021
1.6
1.6
27
1/5/2022
0.8
0.8
28
2/1/2022
1.3
1.3
1.9
1.9
F3/8/2022
4/5/2022
1.6
1.6
5/4/2022
2.3
2.3
32
6/7/2022
2.5
2.5
33
7/5/2022
1.8
1.8
34
9/13/2022
1.4
1.4
35
10/4/2022
1.3
1.3
36
12/6/2022
< 0.5
0.25
37
1/10/2023
0.7
0.7
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
21024 FW RPA 2023, data
-10- 5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par19
Date Data
1 8/13/2018 <
2 9/11/2018 <
3 11 /30/2018 <
4 2/6/2019 <
5 7/10/2019 <
6 10/1/2019 <
7 1 /7/2020 <
8 3/3/2020 <
9 5/18/2020 <
10 9/22/2020 <
11 10/6/2020 <
12 3/2/2021 <
13 6/7/2021 <
14 9/14/2021 <
15 12/9/2021 <
16 3/8/2022 <
17 6/7/2022 <
18 9/13/2022 <
19 12/6/2022 <
20
21
22
23
24
25
26
27
28
29
3
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
Selenium
BDL=1/2DL
Results
2 1
Std Dev.
2 1
Mean
2 1
C.V.
2 1
n
1 0.5
1 0.5
Mult Factor =
1 0.5
Max. Value
1 0.5
Max. Fred Cw
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
Use "PASTE SPECIAL Par20
Values" then "COPY"
. Maximum data
points = 58
0.6053
0.3460
19
1.22
1.0 ug/L
1.2 ug/L
Use "PASTE SPECIAL
Silver Values" then "COPY"
. Maximum data
points = 58
Date
Data
BDL=1/2DL
Results
1
8/13/2018
<
0.5
0.25
Std Dev.
1.2733
2
9/11/2018
<
0.5
0.25
Mean
0.5421
3
11/30/2018
<
0.5
0.25
C.V.
2.3487
4
2/6/2019
<
0.5
0.25
n
19
5
7/10/2019
<
0.5
0.25
6
10/1/2019
<
0.5
0.25
Mult Factor =
2.24
7
1/7/2020
<
0.5
0.25
Max. Value
5.800 ug/L
8
3/3/2020
<
0.5
0.25
Max. Fred Cw
12.992 ug/L
9
5/18/2020
<
0.5
0.25
10
9/22/2020
<
0.5
0.25
11
10/6/2020
<
0.5
0.25
12
3/2/2021
<
0.5
0.25
13
6/7/2021
5.8
5.8
14
9/14/2021
<
0.5
0.25
15
12/9/2021
<
0.5
0.25
16
3/8/2022
<
0.5
0.25
17
6/7/2022
<
0.5
0.25
18
9/13/2022
<
0.5
0.25
19
12/6/2022
<
0.5
0.25
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
21024 FW RPA 2023, data
5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par21
Zinc
Use"PASTE SPECIAL
Values" the "COPY"
Par22
. Maximum data
points = 58
Date Data
BDL=1/2DL
Results
1
8/13/2018
35
35
Std Dev.
11.5564
1
2
9/11/2018
52
52
Mean
40.4474
2
3
9/13/2018
46
46
C.V.
0.2857
3
4
11/6/2018
47
47
n
38
4
5
11 /30/2018
47
47
5
6
2/6/2019
56
56
Mult Factor =
1.06
6
7
6/4/2019
34
34
Max. Value
72.0 ug/L
7
8
7/2/2019
38
38
Max. Fred Cw
76.3 ug/L
8
9
7/10/2019
31
31
9
10
10/1/2019
37
37
10
11
1/7/2020
36
36
11
12
3/3/2020
40
40
12
13
3/3/2020
40
40
13
14
5/5/2020
32
32
14
15
5/18/2020
72
72
15
16
7/7/2020
33
33
16
17
9/22/2020
25
25
17
18
9/22/2020
25
25
18
19
10/6/2020
32
32
19
20
1/5/2021
69
69
20
21
3/2/2021
39
39
21
22
4/6/2021
31
31
22
23
6/7/2021
52
52
23
24
7/5/2021
38
38
24
25
9/14/2021
40
40
25
26
10/5/2021
44
44
26
27
12/9/2021
50
50
27
28
1 /5/2022
14
14
28
29
2/1/2022
49
49
29
30
3/8/2022
49
49
30I
31
4/5/2022
50
50
31
32
5/4/2022
46
46
32
33
6/7/2022
41
41
33
34
7/5/2022
24
24
34
35
9/13/2022
39
39
35
36
10/4/2022
27
27
36
37
12/6/2022
39
39
37
38
1/10/2023
38
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
Use "PASTE SPECIAL
Chlorodibromomethane Values" then "COPY"
. Maximum data
points = 58
Date Data
BDL=1/2DL
Results
6/1/2019
1.21 1.21
Std Dev.
0.4099
9/1/2020 <
1 0.5
Mean
0.7367
3/1/2021 <
1 0.5
C.V. (default)
0.6000
n
3
Mult Factor =
3.00
Max. Value
1.210000 Ng/L
Max. Fred Cw 3.630000 Ng/L
21024 FW RPA 2023, data
-12- 5/24/2023

REASONABLE POTENTIAL ANALYSIS
Par23
Use "PASTE SPECIAL Par24
Chloroform
Values then COPY
. Maximum data
points = 58
Date Data
BDL=1/2DL
Results
1 6/1/2019
6.74 6.74
Std Dev.
1.7746
1
2 9/1/2020
6.08 6.08
Mean
5.4033
2
3 3/1/2021
3.39 3.39
C.V. (default)
0.6000
3
4
In
3
4
5
5
6
Mult Factor =
3.00
6
7
Max. Value
6.740000 Ng/L
7
8
Max. Pred Cw
20.220000 Ng/L
8
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
Use "PASTE SPECIAL
0
Values" then "COPY"
. Maximum data
points = 58
Date Data BDL=1/2DL Results
Std Dev.
NO DATA
Mean
NO DATA
C.V.
NO DATA
n
0
Mult Factor =
N/A
Max. Value
N/A
Max. Pred Cw
N/A
21024 FW RPA 2023, data
-13- 5/24/2023

Roxboro WWTP - Outfall 001
NCO021024 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 5 MGD
MAXIMUM
Qw (MGD) =
5.0000
1Q10S (cfs) =
0.00
7Q10S (cfs) =
0.00
7Q10W (cfs) =
0.00
30Q2 (cfs) =
0.00
Avg. Stream Flow, QA (cfs) =
4.00
Receiving Stream: Marlowe Creek HUC 03010104
DATA POINTS = 58
WWTP/WTP Class: Grade IV
IWC% @ 1Q10S =
100
IWC% @ 7Q10S =
100
IWC% @ 7Q10W =
100
IWC% @ 30Q2 =
100
IW%C @ QA =
65.95744681
Stream Class:
C
COMBINED HARDNESS (mg/L)
Acute = 47.65 mg/L
Chronic = 47.65 mg/L
PARAMETER
NC STANDARDS OR EPA CRITERIA
Y)
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
TYPE
J
a
z
Applied
Chronic Acute
n # Det. Max Pred Cw Allowable Cw
Standard
Acute (FW): 340.0
Arsenic
C
150 FW 340
ug L
18 0
1.0
Chronic (FW): --- 150.0
Max MDL
Arsenic
C
10 HH/WS
ug/L
NO DETECTS
Chronic (HH): 15.2
No detects - no monitoring or limits required
Max MDL = 2
Acute: 65.00
Beryllium
NC
6.5 FW 65
ug/L
4 0
6.48
Note: n 5 9
C.V. (default)
Chronic: 6.50
No detects - no monitoring or limits required
Limited data set
NO DETECTS
Max MDL = 5
Acute: 5.688
Cadmium
NC
0.9605 FW 5.6880
ug/L
18 1
0.173
Chronic: 0.961
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Chlorides
NC
230 FW
mg/L
0 0
N/A
Chronic:----- 230.0
Acute: NO WQS
Chlorinated Phenolic Compounds
NC
1 A
ug/L
0 0
N/A
------------------------------
Chronic:----- 1.0
Acute: NO WQS
Total Phenolic Compounds
NC
300 A
ttgL
1 1
74.4
__ _ _______ _____
_ _ _ _ _ _ _ _ _ _ _____
Note: n 5 9
C.V. (default)
Chronic: 300.0
No RP for limited dataset (n<8 samples). No
Limited data set
No value > Allowable Cw
monitoring or limits required
Acute: 1,535.0
Chromium III
NC
199.6661 FW 1534.9549
µg L
0 0
N/A
Chronic:----- 199.7
Acute: 16.0
Chromium VI
NC
11 FW 16
µg L
0 0
N/A
Chronic:----- 11.0 ------------------------------
Tot Cr value(s) < 5 and < Cr VI Allowable Cw
Chromium, Total
NC
µg/L
19 2 4.0 Max reported value = 3
a: No monitoring required if all Total Chromium
samples are < 5 pg/L or Pred. max for Total Cr is <
allowable Cw for Cr VI.
21024 FW RPA 2023, rpa
Page 14 of 15 5/24/2023

Roxboro WWTP - Outfall 001
NCO021024 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 5 MGD
Acute: 19.23
Copper
NC
13.6745 FW 19.2285
ug/L
44 44
34.24
Chronic: 13.67
RP shown - apply Monthly Monitoring with Limit
2 values > Allowable Cw
Acute: 22.0
Cyanide
NC
5 FW 22
10
ug/L
17 1
5.0
Chronic: 5.0
All values < 10 considered compliant; no monitoring
No value > Allowable Cw
or limits required
Acute: NO WQS
Fluoride
NC
1800 FW
ug/L
0 0
N/A
Chronic: -----1,800.0--
-------------------------
Acute: 155.335
Lead
NC
6.0532 FW 155.3350
ug/L
19 2
1.215
Chronic: 6.053
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Mercury
NC
12 FW
0.5
ng/L
0 0
N/A
Chronic:----- 12.0 ---
-------------------------
Acute: NO WQS
Molybdenum
NC
2000 HH
ug/L
18 4
22.7
Chronic: 2,000.0
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute (FW): 578.5
Nickel
NC
64.2509 FW 578.4768
µg/L
37 35
5.6
Chronic (FW): 64.3
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
------------------------------
Monitoring required
Nickel
NC
25.0000 WS
µg/L
Chronic (WS): 25.0
No value > Allowable Cw
Acute: 56.0
Selenium
NC
5 FW 56
ug/L
19 0
1.2
_ _ _ _ _ _ _ _
Chronic: 5.0
_ _ _ _ _ _ _ _ _ _ _ _
No detects - no monitoring or limits required
NO DETECTS
Max MDL = 2
Acute: 0.899
Silver
NC
0.06 FW 0.8988
ug/L
19 1
12.992
Chronic: 0.060
All data < 0.5 ug/L except for one value of 5.8 ug/L on
19 values > Allowable Cw
6/7/2021
Acute: 217.1
Zinc
NC
218.8901 FW 217.1141
ug/L
38 38
76.3
Chronic: 218.9
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Chlorodibromomethane
C
21 HH
µg/L
3 1
3.63000
Note: n < 9
C.V. (default)
Chronic: 31.83871
No RP for limited dataset (n<8 samples). No
Limited data set
No value > Allowable Cw
monitoring or limits required
Acute: NO WQS
Chloroform
NC
2000 FW
µg/L
3 3
20.22000
Note: n < 9
C.V. (default)
Chronic: 2000.00000
No RP for limited dataset (n<8 samples). No
Limited data set
INo value > Allowable Cw
monitoring or limits required
21024 FW RPA 2023, rpa
Page 15 of 15 5/24/2023

Permit No. NC0021024
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/1
(Dissolved)
Chronic FW, µg/1
(Dissolved)
Acute SW, µg/1
(Dissolved)
Chronic SW, µg/1
(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
213.0200 (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-[1n hardness] (0. 04183 8)) • e^{0.9151 [In hardness]-3.1485)
Cadmium, Acute Trout waters
WER*{1.136672-[ln hardness](0.041838)} • e^{0.9151[ln hardness] -3.623 6)
Cadmium, Chronic
WER*{1.101672-[ln hardness](0.041838)} • e^{0.7998[ln hardness]-4A45l)
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. NCO021024
Silver, Acute
WER*0.85 • eA0.72[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.
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. NCO021024
The overall hardness value used in the water quality calculations is calculated as follows:
Combined Hardness (chronic)
_ (Permitted Flow, cfs *Avfz. Effluent Hardness, mg/L)+s7Q10, cfs *Avg. Upstream Hardness, mg/L)
(Permitted Flow, cfs + s7Q 10, cfs)
The Combined Hardness for acute is the same but the calculation uses the 1 Q 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 1 + { [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:
1 Q 10 = used in the equation to protect aquatic life from acute toxicity
Page 3 of 4

Permit No. NC0021024
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.
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
47.65
Permittee submitted DMRs
(Total as CaCO3)
Average Upstream Hardness, mg/L
NA
7Q10 = 0.0 cfs
(Total as CaCO3)
7Q 10 summer (cfs)
0.0
Reported in previous permit Fact
Sheet
1 Q 10 (cfs)
0.0
Calculated in RPA spreadsheet
Permitted Flow (MGD)
5.0
Design flow
Date: April 24, 2023
Permit Writer: Gary Perlmutter
Page 4 of 4

5/24/23 WQS = 12 ng/L
Facility Name Roxboro WWTP / NC0021024
/Permit No.:
Total Mercury 1631E PQL = 0.5 ng/L
Date Modifier Data Entry Value
MERCURY WQBEL/TBEL EVALUATION V:2013-6
Annual Limit 12 ng/L with
Quarterly Monitoring
MMP Required
7Q10s = 0.000 cfs WQBEL = 12.00 ng/L
Permitted Flow = 5.000 47 ng/L
8/13/18
51.9
51.9
> TBEL
9/11/18
16.1
16.1
11/30/18
8.35
8.35
WQBEL< 25.5 ng/L - Annual Average for 2018
2/6/19
4.65
4.65
6/4/19
3.92
3.92
7/10/19
4.43
4.43
10/1/19
1.52
1.52
3.6 ng/L - Annual Average for 2019
3/3/20
2.59
2.59
5/18/20
2.9
2.9
10/6/20
3.99
3.99
3.2 ng/L - Annual Average for 2020
3/2/21
3.57
3.57
6/7/21
3.14
3.14
9/14/21 <
1
0.5
12/9/21
1.1
1.1
2.1 ng/L - Annual Average for 2021
3/8/22
1.3
1.3
6/7/22
1.91
1.91
9/13/22
2.48
2.48
12/6/22
1.19
1.19
1.7 ng/L - Annual Average for 2022

From: Perlmutter, Gary
Sent: Wednesday, April 26, 2023 1:43 PM
To: Derek Clayton
Subject: EXTERNAL: Reduced monitoring; system component list
Hi Derek,
I see that in your current permit there is reduced monitoring of 2/week for BOD, TSS and Fecal
Coliform. If you wish to maintain the reduced monitoring for these parameters, please submit a request
(an e-mail to me is ok) supporting your request that your facility meets criteria for reduced monitoring
(see guidance, attached).
Also, please check the system component list for any updates:
• a septic tank unloading facility
two bar screens
two grit removal devices
two aeration basins (3 MG each)
three secondary clarifiers
a disinfection system (sodium hypochlorite) with two contact chambers
a calcium thiosulfate dechlorination system
two aerobic digesters
sludge dewatering facility
three sludge drying beds.
Thanks again,
Gary
Gary Perlmutter, MSc.
Environmental Specialist II
NCDEQ/Division of Water Resources
NPDES Municipal Permitting Unit

City of Roxboro
Mr. Gary Perlmutter
NC DENR/ DWQ
Attn: NPDES Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
Dear Mr. Perlmutter
The City of Roxboro formerly request a "Reduction of Monitoring Frequencies" for parameters associated with its NPDES
permit k NC0021024. We are making this request in conjunction with our NPDES permit renewal application and have
included support information/data to justify the reduction in monitoring frequencies. If you have questions or need
additional information please contact me at 336-322-6010 or our WWTP Supt. Derek Clayton at 336-322-6000.
T
Allen Brooks Lockhart
City Manager/Permittee
City of Roxboro
105 S. LAMAR STREET • PO BOX 128 • ROXBORO, NORTH CAROLINA 27573 • [phone] • FAX [phone]
www. cityofroxboro. com

Roxboro WWTP
Permit # NCO021024
NPDES
Monitoring Frequencies Reduction
Data
January 2018 - September 2021
Month/
Monthly
Monthly
Month/
Monthly
Monthly Fecal avg. =s
Parameter Year
Avg. mg/I
Max. mg/I Parameter
Year
Avg.
Max. G c
#/100 ml
#/100 ml mean
NH3 Jan-18
0
O'Fecal
Jan-18
7.54
7Z
Feb-18
0.035
0.3'Coliform
Feb-18
8.89
32
Mar-18
0
0
Mar-18
6.35
72
Apr-18
0.12
1.7
Apr-18
11.94
1046
May-18'
0.17
2.1
May-18
--- -7.13
159
Jun-18
0.08
1
Jun-18
8.95
131
Jul-18
0
0
Jul-18
4.41
51
Aug-18
0.39
0.5
Aug-18
13.33
144
Sep-18
0.05
0.9
Sep-18
25.48
2420
Oct-18
0 05
1.2
- Oct-18
8.52
326
Nov-18
0.21'
1
Nov-18
16.49
24N
Dec-18
0.02
0.3
Dec-18
4.24
16
Jan-19
0.02
0.4
Jan-19
6.83
1120
Feb-19
0.08
1.1,
Feb-19
8.93
24201
Mar-19
0.03
0.4,
Mar-19
3.28
2420 - --
Apr-19
0
0
A r-19
2.85
12''
May-19
0
0
May-19
4.61
23
Jun-19'
0.04
0.4
Jun-19
7.98
32
Jul-19
0.09
1.3
Jul-19
6.63
91
Aug-19
0.01
0.2
Aug-19
8.33
-
107
Sep-19
0
0
Sep-19
4.03
48
Oct-19
0.12
1.6
Oct-19
16.72
2420
Nov-19
0.05
0.8
Nov-19
13.35
56
Dec-19
0.04
0.7
Dec-19
10.41
48
Jan-20
0
0
Jan-20
8.48
9.4
Feb-20
0.15
1.3
Feb-20'
11.26
2420
Mar-20
0.02
0.5
Mar-20
3.91
72'
Apr-20
0
0
Apr-20
5.26
108'
Ma -20,
0.31
2
May-20
12.06
2420
Jun-20
0.1
1
Jun-20
8.94
261
Jul-20
0.03
0.3
-
Jul-20
-
2.27'
--
- -
S
Aug-20
0
0
Aug-20'
4.47
86
Sep-20
0.08
1.2
Sep-20
7.49
126
Oct-20
0.12
1.25
Oct-20
4.95
138
Nov-20
0.1
1
Nov-20
17.33
2420
Dec-20
0.32
1.5
Dec-20,
14.14
66
Jan-21
0.07
0.6 -
Jan-21
6.12
69:
Feb-21
0.27
1.5
Feb-21
11.51
727'
Mar-21
0.03
0.4
Mar-21
5.83
19
Apr-21
0.02
0.4
Apr-21
4.13
9
May-21
0
0
May-21
3.8'
22
Jun-21
0.05
0.5
Jun-21
5.37'
387
Jul-21
0.06
1
Jul-21
3.95
57
Aug-21
0
0
Aug-21
5.7
93
Sep-2 1
0.11
1.5
Sep-21
4.77
64
Avg.
0.076556
0.707778
7.11848
133.687

Roxboro WWTP Perrrlit# NCO021024
NPDES Monitoring Frequencies Reduction Data
January 2018 - September 2021
Month/
Monthly
Monthly
Month/
Monthly
Monthly
Parameter,
Year
Avg. mg/I
parameter
Max. mg/I
Year
Avg. mg/I
Max. mg/I
BOD Jan-18
6.79
11.9 TSS
Jan-18
6.47
17.3
Feb-18,
7.1
11.7
Feb-18
9.2
23.5'
Mar-18I
6.19
9.2
Mar-18
7.35
13.9
Apr-18
4.59
8.7
Apr-18
2.92
16.2
May-18
--Jun-18
4.15
10.6
May-18
1.13
14.1
4.71
9.5
Jun-18
0.56
6.1
Jul-18
3.54
6
Jul-18
0
0,
Aug48
4.01
7.2
Aug-18
0.04
4.2
Sep-1-8-
4.62
8.7
Sep-18
2.421
36.5'
Oct-18
2.85
8.8
Oct-18
1.28 i
21.4
Nov-18
4.59
10.2
Nov-18
6.59
24.2
Dec-18
4.63
7.8
Dec-18
3.57
6.6
Jan-19
4.13
7.4
Jan-19
2.93
9.7
Feb-19
5.29
11.9
Feb-19
_
5.77
1T -
Mar-19
4.52
11.7
Mar-19
5.49
14.41
Apr-19
4.05
7.2
Apr-19'
3.32
7
May-19
2.28,
3.2
May-19'
0.19
3
Jun-19
2.78
5.1
Jun-19
-
1.31
---
5.9
Jul-19
2.64
5
Jul-19
0.59
7
Aug-19
3.34
8.5
Aug-19
0.191
3.2
Sep-19
3.51
8.2
Sep-19
0',
-
0
Oct-19
3.85
5.5'
Oct-19
3.67
22.8
Nov-19
- - -
5.15'
7.7
Nov-19
3.85
5.4
Dec-19,
----
5.09
6.6
Dec-19
4.01
-
11
Jan-20'
4.36
7.2
Jan-20
5.38
7.9
Feb-20
5.22
14.1
Feb-201
4.19
9.5
Mar-20
5.73
10.7
Mar-20'
3.25
9.6
Apr-20
6.19'
9.4
Apr-20
5.14
13
May-20'
6.86
20.5
May-20
7.7,
25.9.
Jun-20.
4.24
6.3
Jun-20
3.12
9.9
Jul-20
3.16
4.7
Jul-20
0.48
3.6
Aug-20
3.41
5.2
Aug-20
1.01
4
Sep-20
4.94
12.6
Sep-20
1.91
18.7,
Oct-20'
_ 5.48
11.7
Oct-20
3.98
10.61
Nov-20
----
5.58
_
11.9
Nov-20
5.34
19.6'
Dec-20
6.6
- -
14.5
-
Dec-20
8.53
- --
28.4
Jan-21
6.39'
11.3
Jan-21
5.93
16.3
Feb-21
$.41
19.4
1`eb-21
7.21
28.8,
Mar-21
5.49
10
Mar-21
4.87'
7.4
Apr-21
3.69
4.4
Apr-21
2.13
4.2
May-21
3.26
-
4.2
May-21
3.46
5.4
Jun-21
3.04
6.6
Jun-21
1.42
6.9
Jul-21
3.09
6.8
Jul-21
0.62
8.7'
Aug-21'
2.47
3.9
Aug-21
0
0
Sep-21
3.14
8.4 --
Sep-21'
1.19
11.5
avg.
4.558889
8.935556
3.212632
12.00667

Roxboro WWTP NCO021024
NPDES Monitoring Frequencies Reduction Data
2018 - 2021 (BOD, Nh3 winter / summer limits)
Parameter Month/ Monthly Monthly Parametet Month/ Monthly Monthly
Year Avl[_mgn Max. Mgn Year Avg. mgA Max.
BOD
6.79
11.9
NH3
Jan-18
0
0
--Jan-1-8
- -- -_
Feb-18
7.1
11.7
Feb-18
Mar-18
0.035
0.3
_
Mar-18
6.19
9.2
_
0
_ 0
Nov-18
4.59
10.2
NOV-18
0.21
1
Dec-18
4.63
7.8
Dec-18
0.02
0.3
Jan-19
4.13
_
7.4
Jan-19
0.02
0.4
Feb-19
- 5.29
11.9 11.9
Feb-19
_ _0.08
0.03
1.1
Mar-19
_ 4.52
5.15
11.7
Mar-19
_ 0.4
Nov-19
7.7
Nov-19
_ _0.05
0.04
0.8
0.7
Der,19
5.09
6.6
Dec-19
_
Jan-20
4.36
7.2
Jan-20
0
0
_
Feb-20
5.22
14.1
Feb-20
0.15
1.3
Mar-20
5.73
10.7
Mar-2-0
0.02
- -0.1
0.5
- -
Nov-20
5.58
11 .9
Nov-20
1
Deo-20
6.6
14.5
Dec-20
0.32
1.5
Jan-21
6.3911
11.3
Jan-21
_ 0.07
- 0.27
0.6
_
Feb-211
8.411
19.4
1 Feb-21
1.5
Mar-21
5491
10
Mar-21
0.03
0.4
WINTER
AVG
1 5.6255551
10.84444
AVG
0.080278
0.655556
Current Limits Effective 10/1/2019 -
NOTE: Due to W WTP Upgrade NH3 limits were extended.
WRITER UMITS... BOO ... MONTHLY AVG. 20.OMG/L WEEKLY AVG 30.0 MG(L INH3 ... MONTHLY AVG. 1.8 MG/L WEEKLY AVG. 5.4 MG/L
SUMMER UNUTB._BOD... MONTHLY AVG. 16.0 MGA. WEEKLY AVG. Z4.0 MGA. NH3... MONTHLY AVG. 1.0 MGIL WEEKLY AVG. 3.0 MGIL
SUMMER
_ SOD
-18
4.59
-- 4.15
8.7
NH3
Apr-18
Ma 18
0.12
1.7
--
M -18
10.6
0.17
2.1
-
Jun-18
4.71
9.5
Jun-18
0.08
0
1
0
Jul-18
3.54
6
Jut18
Aug-18
4.01
- -4.62
7.2
18
0.39
0.5
Sep-18
8.7
Sep-18
0.05
_ 0.9
1.2
Od-18
- 8.8
Oct-1_8
0.05
r-19
_ _2.85
4.05
7.2
Apr-19
0
0
Ma -19
2.281
3.2
_
Ma -19
0
0.04
0
--0.4
Jun-19
2.78
5.1
Jun-19
Jul-19
2-64
5
Jut19
0.09
1.3
_
Aug-19
3.34
8.5
19
0.01
0.2
Sep-19
3.51
8.2
19
0
0.12
_ 0
1.6
Oct-19
3.85
5.5
Oct 19
Apr-20
6.19
9.4
r-20
01
0
Ma 20
6.86
20.5
Ma 20
0.31
2
Jun-20
4.24
6.3
Jun-20
0.1
1
Jul-20
3.16
4.7
Jut20
0.03
_ 0.3
20
3.41
5.2
20
0
0
1.2
Sep-2-0
__- 4.94
12.6
_ ..
Sep-20
0.08
Oct-20
5.46
11.7
Oct-
0.12
1.25
Apr-21
3.69
4.4
Apr-21
0.02
0.4
May-21
Jun-21
3.26
4.2
M 21
0
_
0-
0.5
3.04
6.6
Jun-21
0.05
Jul-21
3.09
6.8
3.9
Jul-21
0.06
1
Aug-21
2.47
Aug-21
0
0.
Sep-21
3.14
8.4
21
0.11
1.5
SUMMER
Ave
3.819231
7.623077
AVo
0.072308
0.706769

Roxboro WWTP System Component List
As of 4/28/2023
• Two Bar Screens
• Two Grit Removal Devices
• Two Aeration Basins (3 MG Each, only one in operation because permit compliance is achieved
without the electrical cost of running both)
• Three secondary clarifiers (only two in operation, east clarifier was taken offline to
accommodate the WWTP upgrade, will be brought back online when the treatment /solids are
transferred to the Oxidation Ditch)
• A disinfection system (sodium hypochlorite) with two contact chambers
• A calcium thiosulfate dichlorination system
• Four aerobic digesters (two were added and online as part of the current WWTP upgrade)
• Sludge dewatering facility
• 1.5 sludge drying beds ... (the sludge dewatering facility utilized one of these beds and the two
new aerobic digesters used %= of another)
It is anticipated that the repair to the Oxidation Ditch floor that put the Roxboro WWTP upgrade on hold
will be completed in August of 2023. The new 2.4 MG, 5.0 mgd ditch rated multiple ring oxidation ditch
system is expected to come online at some point after the repair is made . As per A to C NCDEQ RRO
will be notified in advance.

Attachment: Scheduled Improvements
2.5
Completion of the $23,000,000 upgrade to the City of Roxboro W WTP which began on July
23rd 2018 has and continues to be delayed due to construction related issues with the Oxidation
Ditch. At this time there is no set date for completion and transfer of treatment into the
Oxidation Ditch. Currently, all biological treatment still occurs in the existing activated sludge
basins.
The W WTP upgrade became necessary when the City's NPDES permit limit for NH3 was
reduced from 5mg/l to 1 mg/l in the 2013 permit.
UPDATE
4/28/2023
Repair work has begun on the construction related issues with the new Oxidation Ditch, current
estimates have this work being completed in August of 2023.

Reduction in Frequency Evalaution
Facility:
Roxboro WWTP
Permit No.
NC0021024
Review period (use
03/2020 - 02/2023
3 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
violations
N
# of non -
Monthly
3-yr mean
# daily
# daily
Reduce
Weekly average
50%
200%
200%
monthly
# civil penalty
Data Review
Units
average
(geo mean
< 50%?
samples
<15?
samples
< 20?
> 2?
> 1?
Frequency?
limit
limit
MA
for FC)
MA
>200%
WA
>200%
limit
asessment
(Yes/No)
violations
BOD (Weighted)
mg/L
26.50
17.67
8.8
4.27
Y
35.33
0
Y
0
N
0
N
Y
TSS
mg/L
45.00
30.00
15
1.93
Y
60.00
0
Y
0
N
0
N
Y
Ammonia (weighted)
mg/L
4.00
1.33
0.7
0.17
Y
2.67
0
Y
0
N
0
N
Y
Fecal Coliform
#/100
400.00
200.00
1001
6.796032
Y
800 8 Y
0
N
0
N
Y

City of Roxboro
Mr. Gary Perlmutter, MSc.
Environmental Specialist II
NCDEQ/ Division of Water Resources
NPDES Municipal Permitting Unit
Subject: Draft NPDES Permit NCO021024
Roxboro WWTP
Person County
Grade IV Biological WPCS
SIC Code 4952
Dear Mr. Perlmutter:
The City of Roxboro NC would like to offer the following comments concerning the DRAFT NPDES permit
NCO021024 for its WWTP.
Mr. Andrew M. Oakley is no longer the City of Roxboro's Public Services Director. Mr. Kenneth Griffin is
the new City of Roxboro Public Services Director and the process of naming Mr. Griffin "permittee" will
begin as soon as possible.
Page 2 of 11 of the Draft permit list both current and future components at the Roxboro WWTP. An
updated list was emailed to you on 4/28/23, it included this notable change;
1. 1.5 sludge drying beds...( the sludge dewatering facility utilized one of these beds and the two
new aerobic digesters used A of another)
We request that notification be given when EPA publishes 40 CFR part 136 Final PFAS Method for
wastewater in the Federal Register in -order to meet the 15` full calendar quarter following six (6) months
after publication monitoring requirement included in the draft permit.
Conductivity. Downstream conductivity is just 5% higher than upstream therefore we don't see why
monitoring our effluent for it is necessary. At a minimum we request that the monitoring be reduced to
once per week which is 250 plus samples/data points over the five year permit term.
105 S. LAMAR STREET • PO BOX 128 • ROXBORO, NORTH CAROLINA 27573 • [phone] • FAX
[phone]
wivw.cityof oxboro.com

Ammonia. The City of Roxboro request that the modified compliance Special Condition A. (1) Effluent
Limitations and Monitoring Requirements, Footnotes 3 and 4 that expired on November 30, 2021 be
reinstated through March of 2024. Completion of the Roxboro WWTP upgrade which began on July 23'd
of 2018 continues to be delayed due to construction related issues with the Oxidation Ditch. A repair
resolution was approved and the repair work to the structure was started on April 3`d 2023, the
Oxidation Ditch repair is scheduled to be completed in late 2023. Once this occurs the biological
treatment process will be transferred from the existing activated sludge basins to the Oxidation Ditch.
The requested March 2024 compliance schedule would also allow time to get the new system up and
running efficiently after the projected solids transfer.
Additionally, the City of Roxboro had an outside consultant (AquaLaw) compare our data (Nh3, ph,
temp.) against EPA's 2013 Freshwater NH3-N criteria. Their findings and recommendations are as
follows:
Roxboro objects to the ammonia ("NH3-N") limits, as proposed, and requests different numeric limits for
the following reasons. The proposed limits (summer 1.0 mg/I monthly average/3.0 weekly; winter 1.8
mg/I/5.4) are unnecessarily stringent for protection of aquatic life, arbitrary and unsupported legally. We
note that we have had no ammonia toxicity as verified through our passing all of our WET tests during the
prior permit cycle.
EPA's 2013 Freshwater NH3-N criteria ("EPA 2013") are the nationally recommended criteria for NH3-N
toxicity. Those criteria are so stringent that many states have not adopted them (also pointing to the fact
that WET testing results demonstrate no need for more stringent NH3-N criteria). EPA's recommended
criteria are highly pH and temperature dependent. We propose the application of EPA's 2013 creiteria
with the pH and temperature inputs set at the upper 75th percentile values. The upper 75th percentile
represents a reasonable, largely worst -case, application of EPA 2013.
We compiled the daily pH and temperature records for our facility for 2020, 2021 and 2022, and then
ranked the data separately for the DEQ-defined summer and winter tiers. The data are included in the
tables following, including values for a more stringent 90th percentile approach (although we believe that
the 75th percentile is adequately conservative, particularly as used with both variables for EPA 2013
criteria):
Summer 2020-2022 Effluent Data
Max
75th
90th
pH
7.4
7.2
7.3
T
26.4
24.2
25.1
Winter 2020-2022 Effluent Data
Max
75th
90th
pH
7.4
7.1
7.1
T
20.8
15.3
16.7

The approximate EPA 2013 criteria values are the following;
EPA 2013 NH3-N WQC (mg/1)
Summer Acute/Chronic
Winter Acute/Chronic
75`h
9.7/1.3
22/2.4
90`h
7.9/1.2
20/2.2
For permit limits Roxboro requests that DEQ use an approach recommended by U.S. EPA in its Technical
Support Document for Water Quality -Based Toxics Control ("TSD"). The first TSD option is to use the
criteria values themselves as limits. Under this approach (and using upper 75`h percentile pH and
temperature), the summer NH3-N limits would be 1.3 mg/I monthly average and 9.7 mg/I weekly average.
The wintertime limits would be 2.4 and 22 mg/I, monthly and weekly. Again, considering the use of
conservative 75`h percentile values for both the pH and temperature input variables, these resulting NH3-
N limits will be highly conservative and protective of aquatic life. This has been confirmed by our extensive
W ET testi ng.
EPA's TSD alternate statistical procedure for limits calculations generally produces similar numeric values
to the direct use of wasteland allocations/criteria. We have not calculated those alternate values but it
generally appears that in this case the permit limit values would be comparable.
Total Copper limits. As the copper data below demonstrates, we had issues in the second half of 2020,
especially during December that were construction related. We strongly believe the December V 2020
and December 22"d 2020 copper results were related to three things.
I. One of the three final clarifiers being off-line due to the plant upgrade.
2. 1&1 due to heavy rain.
3. In anticipation of the Oxidation Ditch coming on-line, the contractors installed an influent
diversion box in August of 2020. This diversion box allows influent flow to the OD through a 36"
pipe and flow to the equalization basins through a 24" telescoping valve. Since installation and
currently the 36" pipe to the OD is plugged so all of ourflow since August of 2020 goes through
the 24" telescoping valve to the existing activated sludge basins which eventually become
equalization basins after the OD comes on-line. The 24" telescoping valve was not designed to
carry all the influent flow so during heavy rain events it creates a "funnel" effect and water
backs up.
With the installation of the influent diversion box in August of 2020 there was a learning curve for our
staff that resulted in two bypass events from the diversion box and how they had to manage heavy rain
events like those from December 2020. Since that time, we have had heavy rain that resulted in high
flows on many occasions but we haven't had another bypass or copper result anywhere near the 32 ug/I
from 12/1/2020. Since that time, you can see that our copper average has come down steadily and our
maximum value since 1/1/21 is 10 ug/L. We do not believe there is reasonable potential if DEQ would
simply base the review on the data since 1/1/21. We believe these data are the more representative

data because the 2020 data came when the facility was in an upset condition due to the construction
issues mentioned above. Thus, we ask DEQto rerun the RP calculations using data from 1/1/21 and with
recognition of the significant downward trend since 1/1/21 in both the max and annual values. That
trend is due to the lessons learned and the management strategies applied as a result of high flows
during heavy rain events after the influent diversion box tie-in and the resulting stabilization of the
operation of the facility. We believe this stabilization of operation will continue to improve with the
Oxidation Ditch & Final Clarifier coming online and the completion of the WWTP upgrade. Again, the
second half of 2020 copper data are not representative of the plant performance going forward.
Date
ug/I
Date
ug/I
Date
ug/I
Date
ug/I
1/7/2020
6
1/5/2021
8
1/5/2022
3.6
1/10/2023
6
2/4/2020
9
2/3/2021
6
2/1/2022
7
2/7/2023
5
3/3/2020
8
3/2/2021
8
3/8/2022
5
3/7/2023
6
4/7/2020
11
4/6/2021
8
4/5/2022
6
4/4/2023
6
S/8/2020
8
5/10/2021
10
5/4/2022
7
5/2/2023
6
5/18/2020
10
6/7/2021
6
6/5/2022
5
Avg.
5.8
6/3/2020
7
7/5/2021
8
7/5/2022
7
Max.
6
7/7/2020
8
8/3/2021
6
8/2/2022
6
8/4/2020
11
9/14/2021
9
9/13/2022
7
9/22/2020
7
10/5/2021
8
10/4/2022
6
10/6/2020
8
11/2/2021
6
11/8/2022
9
11/3/2020
10
12/9/2021
S.6
12/6/2022
7
12/1/2020
32
Avg.
7.383333
Avg.
6.3
12/8/2020
13
Max.
10
Max.
9
12/10/2020
12
12/11/2020
12
12/22/2020
18
12/29/2020
8
Avg.
11
Max.
32

Fact Sheet NPDES Permit No. NCO021024 6.6. Mercury Statewide TMDL Evaluation pg. 7 & 8 of 11
We disagree with including an annual limit of 12ng/I because of the reported maximum conc. of 51.9
ng/l from August 2018 monitoring. This 51.9 ng/l was reported on the August 2018 eDMR as instructed
the RRO (Raleigh Regional Office), the original lab result of 92.8 ng/I was averaged with a second
analysis on the same sample which came back as 11.0 ng/I. Please see the attached file (LLHG August
2018 5 26 23), it includes email correspondence between Roxboro WWTP Supt. Derek Clayton and
NCDENR Environmental Program Consultants Vanessa Manuel and Danny Smith. Additional emails
(attached) between the Division of Water Resources PERCS Unit Supervisor Deborah Gore and City of
Roxboro W WTP Lab Supervisor / PT Coordinator Crystal Shotwell indicate that she had talked to Teresa
Rodriguez who issued our current NPDES permit and concluded there was plenty of historical data
showing the original lab result for the August 2018 sample of 92.8 was an anomaly. Also; in the
attached file is a copy of the comments submitted with version 4.0 of our August 2018 eDMR. We
believe that PERCS Unit Supervisor Deborah Gore and permit writer Theresa Rodriguez were correct and
the original sample result of 92.8 was indeed an anomaly based on the historical data and therefore
should have been considered invalid. Based on the information provided here and in the attached file
we request the LLHG 12 ng/I annual limit be removed from the final permit.
Upstream and Downstream DO, Temp., and Conductivity. Since the instream sampling is not required
under the federal program nor by any other State the we are aware of and the City has been doing this
monitoring for years we don't feel that it is necessary to continue it in the new permit. Therefore, we
request that this requirement be removed from the final permit.
Chronic Toxicity. The Roxboro WWTP passed 17 of 17 Chronic Toxicity and all four second species WET
test during the last permit cycle, based on these results we request that this monitoring requirement be
removed from the final permit.
Thank you for taking the time to consider the above requests, we look forward to your assistance in
continuing to protect our local environment.
Sincerely,
Allen Brooks Lockhart
City Manager
City of Roxboro

"mum. Viueea ...... 6
HE: iErterrmg Fbeb" V%rVM lnw L&VW M0rawy
••,�.sl•.. Odober 2. 2018 09.03 AM
t- Derek CloyFon • :..,a, . :. SrnM, nervy :.
C e . Tammy Wprran i ....:. Cryitel SIfOt�retl Vs:._... :. - -- - . Andrew Oakley
Derek —
Because permittees are required to report all monitoring data from samples collected from the
effluent, you should revise the eDMR to include the additional monitoring data, add a comment to the
eDMR noting your concerns with the data result(s) and attach a copy of your email to the signed eDMR
(2 copies) you submit to Central Files. Your comments and attachment, as included on the eDMR, will
be part of the final record for the monitoring report.
If you have additional questions, please feel free to contact me.
Vanessa I— Manuel
Environmental Program consultant
Division of water Resources — Raleigh Regional Office
Department of Environmental Quality
919 791-4255 office
vanesm snug-4> ckmggy
Physical: 380D Barrett Drive. Raleigh, NC 27609
Making: 1628 Mail Service Center, Raleigh. NC 27689-1628
=i tc7e: r' �'�5,►ivP?:J '?'�:c !G &�rc!'�•cr^ :re'S is?:�`C'S� `F 5i1:'.'c','.r ! � �j'r,',
From: Derek Clayton <[e-mail]>
Sent: Tuesday, October 02, 2018 7:26 AM
To: Manuel, Vanessa <vanessa-manuel@nedenrgov>; Smith, Danny <dannysmith@nedenrgav>
CC: Tommy Warren <[e-mail]>; Crystal Shotwell <eshotwell@cFtyofroxboro_com>;
Andrew Oakley <[e-mail]>
Subject: (External] Roxboro WWTP Low Level Mercury
Good morning Vanessa and Danny,

On 9/20/181 had a phone conversation with Danny concerning bath influent and effluent low ;MM Hg
samples that were taken in mid August. I folbwed up the phone CM with an email on the saute day. As a
result we subrrritbed our August 2018 edam without those resuU iurowi V that once we did get then we
wouid kxk de therm in a v+tvsion 2.0 edmc
Due to uVoing lab e**xrient issues our convnerial Lab (Mmitech Inc.) was unable to analyze the samples
so they shed dram to Pam Analytical. I received the results of these samples via email on 9/27118 while
on vacation and forwarded the results to oar Lab Supervisor (crystal Shotvveli) asiclrrg her to Check with our
commercial lab because the effluent rwere 3OX highs than average. Please review the lfoiiowirg as to
why we feel tie results are not valid.
L Wp were tali that we were not the only munkipality that received msuit5 way higher than nonml an
samples that Mertbwh Inc— had forwarded to trace Analytical during the same tkne frame.
2. Field U3nks higher than norms.
3. Raxboro low Lewd Hq pram tirsbory..1012 am. 1.67 ng/l, 2013 avg. 2.13 ng/l, 2014 avg. 371
n0/4 2015 avg. 3.16 rrg/& Ml5 mq. 5i.4tZ nalk 2017 avg. 3.71 r9/4 3/4/1tl...Lti2 ng/L
The 2012 - 3/2018 average dritiat mercury for our facility Is 3A7 ng/t and the maximum for the
same period was 10.9 nq/l so when I saw an effluent low *-,d Hg result from 8/13/18 at US ng/1 I was
and still am very d6eitkai. An influent Sample v+ras tahm on the same date and It was repod W at 42.3 nq/t
Based an this infq radon I would Bice to brow how NOOM would like me to use Owse resins. Strould I
report them in a version 2 0 edw as we had planned and attach a dopy of this email? Or is these somethlrg
else we shoukl do? Our Lab Supervisor / PT C'Qovdk&*or will also be consu" with her HCDENR
Pretrwitrz t CWAaCts to get guidance on using or not using this effluent result in our Pretreatment LTMP.
We oonlaCtBd Pace labs yesterday and asired if our 8/13/18 samples were still there and informed than OWK
we would Glee bo halve them bade if they are. W fe sti8 yr king to ftncl out v 4WW lhay are or noL We also
have anadw sea of Influent and EffhxN t low fr vel ffwr ury samples taken on 9/11/18 that weir sent to
Mew frtc.. These samples have been shipped to Summit labs in Ohio fur analysis.
I lode forward to your nesporue eonceft this matter and if you treed additional mformation please don't
hesbte to 00.
Derek Clayton
W WTP Suet
City of ftoodxuo
336 999 8232

From: Crystat Shotvaa crbo►4es0caycrroxboro cosh
Subject: Find: [Etdertmq Low Lmd HD for August LTM
Date. October 25, 2018 at 855 AM
To: Derek Ctayfon eldaytonOcityofroxboro.com
Begin forwarded message_
Fion "Gore, Deborah' <detwrah.9ore4nW6nr.vwv_>
Subject: RE: [External] Low Level Hg for August LTM
Dale: October 26. 201 Bat 8.06:35 AM EDT
Tw Crystal ShnotweN <r�,pyves 0y9frorl2rc.com>, "Hassan, Monti' <monjl.hassongncdenr.agy>
CC:'2rharhg, Chang" <oheng.zhana�na�lenr.guv>, 'Manuel, Vanessa' <vaneSSa.man{t�l;;ncders.g5�v_>
Cgood Morning,
As faf as using the data in the HWA t would allow the use of the second value. 1 t.0 ugA, based on historical data. Now as to what to report
on the DMA... I m not sure.
There is no limit for mercury, but the rambars are used in the APA. Teresa Rodriguez just issued the permit so I talked to her about how
they use the numbers and she said that the permit would probably decide the sarne as PERCS would for the HWA_ Plenty of historical data
showrirN that the 928 Is an anomaly. WE she didn't reatry know the a ewer to what to put on the DMR.
It possible I would put both numbers In the Cell and explain on the batik 111 192.81. But 1 doubt the system will allow that So then, my
recommendation is that Roxboro report the average on the 0 MR with an explanation and bath values on the back
I have copied the RRO to see if they have an alternate suggestion since they are the ones who really review the data and take the action.
Delwrah Gore
PERCS Unit Supervisor
Division of Water Resources
Department of Environmental Quality
919-707-3624 ofriee
979-807-6489 tact
Qebolah, oorg 2 n%len r. goy
1617 Mait Service Center
Raleigh, NC 27699-1617
Email correspondence to and from this address Is subject to the North Carolina Public Records Law and may be disdosed to third parties.
-----Onginel Message ----
From: Crystal Shotwell ecrboww0dtyofroxboro.corn>
Sent: Thursday, October 25, 2018129 PM
To: Hassan, Alonli -anofW hessanQncdenr.gov>
Cc: Gore, Deborah <debor;ah.gor"noJw.gov>
Subod: "ema►j Low Level Hg for August LTM
CAUTION- External email. Do not dick links or open attachments w t w verified. Send all suspicious email as an of ec hmert to Report
Sporn <mmfto:report.sparn 9nc_gov>
Good afternoon Monti.
l orAected my LTM samples in August and shgpW them to Mertech to have thrarn analyzed. They were hawM iesuvs with their Low Level
fig madxre and were not able to run our samples. Without d*ck69 with us, they srxpped our samples to Pace Arnaiytiaed and had tern to
analyze tha samples and we received a 92.8 ng& on our effluent sample. yft Wnnv +atety knew this ooutd riot be right and argued this with
Meritech and Pace. Pecs stood by It, So me had MarteGh got our sample track from Pace and shge it to Summit Labs and have them
analyze A. Summit analyzed tt and the result vets 11.0 ngA_, which is still higher than rnor 4 but more believabio than the first.
My question to you is, can I throw, out that first number and use 11.0 ng& or do I have to average the two numbers Would this be
considered a split sample?
Crystal Shotwak
Pretreatment Coordktazor/lAboratory Supervisor City of Roxboro W WTP
M599-8232

MPM PERMIT NO.: Nt^_M1024 PERMIT VERSION_ 4.0 PERMIT STATUE
Expeed
FACILITY NAME: Roxbum WWW CLAM: WW4. COUNTY: Pcmn
OWNER NAME City of Roxboro ORe. Daeit L m o" ORC CERT NUMWAO 926/
GRAD& WWA ORCIIAS CHANCM No `—
eDMIR PERIOD- 09,201 /(AMSa 2018) VERS Mt 4.0 STATU& huaesnad
Rep"
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Roxboro WWTP Fact Sheet Addendum NCO021024
Comments to the draft permit NC0021024, which was public noticed for 30-day comment period on
5/25/2023, were provided by the City of Roxboro with several requests. No comments were received from
any other party. Individual comments by the City and Division responses (in blue) are provided below.
1. Change in Permittee Contact
a. Mr. Kenneth Griffin is the new City Public Services Director. Response: requires
completion of Permit Name/Ownership form, received on 8/15/2023; updated contact
noted; will address in future letters.
2. Supplement to Permit Cover Sheet (page 2 of 11)
a. Add 1.5 sludge drying beds (sludge dewatering facility utilized one of these beds and the
two new aerobic digestors used % of the other). Response: added as requested.
3. PFAS Monitoring
a. The City requests to be notified when the USEPA publishes 40 CFR part 136 Final PFAS
Method for wastewater in the Federal Register in order to meet delayed monitoring
requirement. Response: comment noted.
4. Conductivity
a. The City requests reduction of monitoring frequency to weekly based on slight increase
in downstream concentrations Response: monitoring frequency reduced to weekly as
requested to better match instream monitoring frequency.
5. Ammonia
a. The City requests to reinstate and extend the compliance schedule through March 2024.
Response: Ammonia data were evaluated from 12/1/2022, when the compliance
schedule ended, through May 2023 and found no exceedences of either the monthly
average or weekly average limits, demonstrating compliance (see figure below).
Effluent Ammonia
W k Avg ■ Mo Avg WA Limit — — MA Limit
6.0
5.0
4.0
J
n� 3.0 -
2.0
1.0 ■00 7 —
■
0.0
61�'
IN
Based on this review, extension of the compliance schedule is not needed and will not be
reinstated.
b. The City objects to the proposed Ammonia limits and propose alternate limits be
developed based on EPA's 2013 criteria with stream -specific pH and temperature data,
set at the upper 75th percentile values. Response: a recalculation was made for site -
specific ammonia limit development using available effluent and upstream data and

Roxboro WWTP Fact Sheet Addendum NCO021024
applying default values where data are not available. Available data were obtained from
submitted DMRs from August 2018 — February 2023. For those parameters where data
are available, the 90th percentile was used, following recommendations in the EPA
Technical Support Document (EPA 1991, page 18) to provide adequate protection against
chronic toxicity stream impacts. The resulting inputs are as follows:
Parameter Summer Winter
Effluent Temperature, °C (90th percentile) 25.2 16.6
Effluent pH, SU (90th percentile) 7.3 7.1
Upstream Temperature, °C (90th percentile) 24.07 13.7
Upstream pH, SU (default) 6.8 7.5
Upstream Ammonia, mg/L (default) 1.16 2.25
Calculating these inputs with the facility design flow of 5.0 MGD and the receiving stream
flows of 7Q10 = 0.0 cfs summer and winter, and applying a 2.5 X multiplier to the chronic
allowable concentration (i.e., monthly average) to obtain an acute allowable
concentration (i.e., weekly average) resulted in the following ammonia limits:
Monthly Average
Weekly Average
Summer
1.2
2.9
Winter
2.3
5.6
which are comparable to the current limits:
Monthly Average
Weekly Average
Summer
1.0
3.0
Winter
1.8
5.4
Furthermore, as stated in the response to Comment 5 above, the facility is consistently
meeting compliance with the current limits. Because the differences between the site -
specific and current limits are negligible and the facility's ability to comply with current
limits, no changes were made to the ammonia limits.
6. Copper
a. The City requests that the RPA be run using effluent data beginning 1/1/2021 as older
data resulted in the proposed limits. Response: Considering the data are valid and there
is a decrease in concentrations beginning 1/1/2022, a footnote will be added to the
permit effluent requirements sheet stating that the Permittee may request a re-
evaluation of copper limits after 24 months of sampling for potential monitoring
frequency from monthly to quarterly.
7. Mercury
a. The City requests removal of the annual limit as it is based on a single high value of 51.9
ng/L in 2018, which was previously determined to be an anomaly and thus considered
invalid. Response: The mercury datum in question is found to be over 4.5 yrs old. The
evaluation was rerun using data not older than 4.5 yrs (i.e., from 11/30/2018 to present),
resulting in no limits required. The limit identified in the draft fact sheet was not added
to the permit; therefore, no changes are made to the permit.

Roxboro WWTP Fact Sheet Addendum NC0021024
8. Instream Monitoring
a. The City requests removal of instream monitoring for DO, Temperature and Conductivity.
Response: instream monitoring requirements for the above parameters are based on rule
15A NCAC 02B .0508, and thus will remain in the permit.
9. Chronic Toxicity
a. The City requests removal of Chronic Toxicity monitoring, based on all tests passing.
Response: chronic toxicity is a necessary screening tool of water quality, and is required
by rule 15A NCAC 02B .0508; it will remain in the permit.
Based on the removal of the Mercury annual limit, which represents a relaxion in permit requirements,
the permit will be sent to a second Public Notice, during which the Permittee may submit additional
comments.