NC0021873_Fact Sheet_20230717

Fact Sheet
NPDES Permit No. NCO021873
Permit Writer/Email Contact Nick Coco,[e-mail]:
Date: July 17,2023
Division/Branch:NC Division of Water Resources/NPDES Municipal Permitting
Fact Sheet Template: Version 09Jan2017
Permitting Action:
® Renewal
❑ Renewal with Expansion
❑ New Discharge
❑ Modification(Fact Sheet should be tailored to mod request)
Note: A complete application should include the following:
• For New Dischargers,EPA Form 2A or 2D requirements,Engineering Alternatives Analysis,Fee
• For Existing Dischargers (POTW),EPA Form 2A, 3 effluent pollutant scans,4 2nd species WET
tests.
• For Existing Dischargers (Non-POTW),EPA Form 2C with correct analytical requirements based
on industry category.
Complete applicable sections below. If not applicable, enter NA.
1. Basic Facility Information
Facility Information
Applicant/Facility Name: Town of Mayodan/Mayodan WWTP
Applicant Address: 210 W. Main Street,Mayodan,NC 27027
Facility Address: 293 Cardwell Road,Mayodan,NC 27027
Permitted Flow: 2.5 MGD with 3.0 MGD and 4.5 MGD expanded tiers
Facility Type/Waste: MAJOR Municipal; 87.8%domestic, 12.2%industrial`
Facility Class: Grade III Biological Water Pollution Control System(2.5 MGD)
Grade IV Biological Water Pollution Control System(3.0 and 4.5 MGD)
Treatment Units: Mechanical bar screen,Dual path aeration basins, Secondary clarifiers,
Liquid Chlorination,Liquid Dechlorination,Effluent flow meter, Sludge
thickener,Aerobic digester,Backup generator
Pretreatment Program(Y/N) I Y; LTMP
County: Rockingham
Region Winston-Salem
*Based off of permitted flows.
Briefly describe the proposed permitting action and facility background: The Town of Mayodan has
applied for an NPDES permit renewal at 2.5 MGD for the Mayodan WWTP. This facility serves a
population of approximately 5,700 residents across the Towns of Mayodan, Stoneville and Madison, as
well as 3 non-categorical significant industrial users(SIUs)via a Division-approved pretreatment
program. Treated domestic and industrial wastewater is discharged into the Mayo River, a class
C waterbody in the Roanoke River Basin. Outfall 001 is approximately 1.4 miles upstream of waters
designated as WS-V.
Sludge disposal: Sludge is land applied under WQ0002672.
Page 1 of 13

History: In 2002 the Town applied for expansion from 3.0 MGD to 4.5 MGD in order to add service to
the Towns of Stoneville and Madison. In 2004,the Town completed facility upgrades and expanded the
facility's operating capacity to 4.5 MGD. In 2007, as a result of loss of a major SIU,the Town applied for
a flow reduction modification to the permit in order to downgrade to 2.5 MGD,thereby going from a
Class IV to a Class III facility with corresponding relaxed limits and monitoring conditions. The 3.0
MGD flow tier is activated once average flow for any calendar year exceeds 80% of the permitted flow
(2.0 MGD). The 4.5 MGD flow tier is activated once average flow for any calendar year exceeds 80%of
the 3.0 MGD flow tier(2.4 MGD). From 2018 through 2022, annual average flow was not observed at
levels equal to or greater than 2.0 MGD for any year.
As the 3.0 MGD flow tier would only be active for 0.4 MGD based on the current practice(80%of the
flow tier), and as the facility is designed for a 4.5 MGD capacity,the trigger for the 4.5 MGD flow tier
has been revised to be activated once average flow for any calendar year exceeds 90%of the 3.0 MGD
flow tier(2.7 MGD).
2. Receiving Waterbody Information:
Receiving Waterbody Information
Outfalls/Receiving Stream(s): Outfall 001 -Mayo River
Stream Segment: 22-30-(10)
Stream Classification: C
Drainage Area(mi2): 312
Summer 7Q10(cfs) 75
Winter 7Q10(cfs): 131
30Q2 (cfs): 150
Average Flow(cfs): 362
IWC (%effluent): 5 %(2.5MGD)
6%(3.0 MGD)
9% (4.5 MGD)
2022 303(d) listed/parameter: Not listed
Subject to TMDL/parameter: Yes- State wide Mercury TMDL implementation.
Basin/Sub-basin/HUC: Roanoke River/03-02-02/HUC: 0301010304
USGS Topo Quad: B 19NW
3. Effluent Data Summary
Effluent data for Outfall 001 is summarized below for the period of June 2018 through October 2022.
Table 1. Effluent Data Summary Outfall 001
Parameter Units Average Max Min Permit
Limit
Flow MGD 1.04 5.513 0.107 MA 2.5
BOD mg/1 7.0 95 <2 WA 45.0
MA 30.0
NH3N summer mg/1 2.2 23.2 0.04 WA 35.0
MA 16.0
NH3N winter mg/l 1.5 8.66 0.04 Monitor&
Report
Page 2 of 13

TSS mg/l 9.26 260 <2.5 WA 45.0
MA 30.0
PH SU 6.5 8.2 6 6.0>pH<
9.0
(geomean)
(geometric)
Fecal coliform #/100 ml 6.2 2420 1 WA 400
MA 200
DO mg/l 8.5 18.2 2.73 Monitor&
Report
DM 28.0
TRC µg/l 23.5 50 14 (<50
compliance)
Conductivity µmhos/cm 356 654.6 73.6 Monitor&
Report
Temperature ° C 16.7 29 2 Monitor&
Report
TN mg/I 8.7 38.75 1.89 Monitor&
Report
TP mg/l 1.9 6.45 0.18 Monitor&
Report
Total Chromium µg/l <5 <5 <5 Monitor&
Report
Total Mercury ng/1 3.6 12.4 < I AA 47
Total Silver µg/1 0.55 < 1 <0.25 Monitor&
Report
Total Copper µg/1 10.3 29 3 Monitor&
Report
MA-Monthly Average,WA-Weekly Average,DM-Daily Maximum,DA=Daily Average
4. Instream Data Summary
Instream monitoring may be required in certain situations, for example: 1)to verify model predictions
when model results for instream DO are within 1 mg/1 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).
If applicable, summarize any instream data and what instream monitoring will be proposed for this
permit action: The current permit requires instream monitoring for pH,dissolved oxygen,temperature,
and conductivity upstream at NC Highway 135 and downstream at NCSR 2177(Dan Valley Road).
Instream monitoring is conducted three times per week during June,July,August and September, and
once per week during the rest of the year. Data was observed from June 2018 to October 2022. The data
has been summarized in Table 2 below.
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Table 2. Instream Monitoring Data Summary
Upstream Downstream
Parameter Units
Average Max Min Average Max Min
Temperature ° C 18.7 29 2 18.8 31 2
DO mg/l 9.2 17.09 6.17 9.3 18.03 1.63
Conductivity umhos/cm 60.2 132.5 6.6 63.1 99.6 6.4
pH s.u. 6.9 9.8 3.4 6.9 8.2 5.3
Students t-tests were run at a 95% confidence interval to analyze relationships between instream
samples.A statistically significant difference is determined when the t-test p-value result is<0.05.
Downstream temperature was greater than 29 degrees Celsius [per 15A NCAC 02B .0211 (18)] on one
occasion during the period reviewed. Downstream temperature was greater than upstream temperature by
more than 2.8 degrees Celsius on 4 occasions during the period reviewed. It was also concluded that no
statistically significant difference exists between upstream and downstream temperature.
Average downstream DO was not below 5 mg/L [per 15A NCAC 02B .0211 (6)] during the period
reviewed. Downstream DO was observed below 4.0 mg/L on 2 occasions during the period reviewed.
Review of concurrent effluent BOD and ammonia data demonstrated no correlation between elevated
effluent BOD or ammonia with the observed dips in DO. Additionally, it was concluded that no
statistically significant difference exists between upstream and downstream DO.
It was concluded that a statistically significant difference exists between upstream and downstream
conductivity,with downstream conductivity being observed consistently higher than upstream
conductivity. As concurrent effluent conductivity was observed at levels consistently greater than that of
the upstream and downstream, it appears the facility effluent may have an influence on instream
conductivity.
pH was observed at levels less than 6 s.u. on 8 occasions [per 15A NCAC 02B .0211 (14)] during the
period reviewed. Upon further review, concurrent upstream pH was observed out of range. Additionally,
it was concluded that no statistically significant difference exists between upstream and downstream pH.
It does not appear that instream pH variability outside of the range of the standard is due to the facility's
effluent.
No changes are proposed to instream monitoring requirements for dissolved oxygen,temperature,
conductivity or pH. In accordance with the dissolved metals implementation strategy, as the facility has a
pretreatment program,total hardness monitoring upstream and in the effluent has been added at a
quarterly frequency.
Is this facility a member of a Monitoring Coalition with waived instream monitoring(YIN):NO
Name of Monitoring Coalition: NA
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): The facility reported one
fecal coliform limit violation resulting in enforcement in 2018. In 2020,the facility reported one TSS
limit violation resulting in enforcement. The facility reported one fecal coliform limit violation resulting
in enforcement in 2021. In 2022,the facility reported one BOD limit violation and two TSS limit
violations resulting in enforcement.
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Summarize the compliance record with aquatic toxicity test limits and any second species test results
(past 5 years): The facility passed 16 of 16 quarterly chronic toxicity tests, as well as all 4 second species
chronic toxicity tests from March 2019 to December 2022.
Summarize the results from the most recent compliance inspection: The last facility inspection conducted
in December 2021 reported that the facility was compliant. The last pretreatment inspection conducted in
August 2022 reported that the facility was compliant.
6. Water Quality-Based Effluent Limitations (WQBELs)
Dilution and Mixing Zones
In accordance with 15A NCAC 2B.0206,the following streamflows are used for dilution considerations
for development of WQBELs: 1Q10 streamflow(acute Aquatic Life); 7Q10 streamflow(chronic Aquatic
Life;non-carcinogen HH); 30Q2 streamflow(aesthetics); annual average flow(carcinogen,HH).
If applicable, describe any other dilution factors considered(e.g., based on CORMIX model results):NA
If applicable, describe any mixing zones established in accordance with 15A NCAC 2B.0204(b): NA
Oxygen-Consuming Waste Limitations
Limitations for oxygen-consuming waste(e.g.,BOD) are generally based on water quality modeling to
ensure protection of the instream dissolved oxygen(DO)water quality standard. Secondary TBEL limits
(e.g., BOD=30 mg/1 for Municipals)may be appropriate if deemed more stringent based on dilution and
model results.
If permit limits are more stringent than TBELs, describe how limits were developed: The existing
limitations for BOD5 are based on a 1994 empirical model developed when the Town was considering
expansion of the Mayodan WWTP to 6.0 MGD,which resulted in TBELs being found to be protective of
dissolved oxygen in the receiving stream. In 2000,the Town instead requested speculative limits be
developed for a reduced capacity of 4.5 MGD. As the empirical model found no contravention of the DO
standard at the 6.0 MGD flow,the TBELs were found to be appropriate for the 4.5 MGD flow tier, and
were applied to all reduced flow tiers in the future when the Town requested operable flow reductions at
their plant.No changes are proposed.
Ammonia and Total Residual Chlorine Limitations
Limitations for ammonia are based on protection of aquatic life utilizing an ammonia chronic criterion of
1.0 mg/1(summer) and 1.8 mg/1(winter). Acute ammonia limits are derived from chronic criteria,
utilizing a multiplication factor of 3 for Municipals and a multiplication factor of 5 for Non-Municipals.
Limitations for Total Residual Chlorine(TRC) are based on the NC water quality standard for protection
of aquatic life(17 ug/1) and capped at 28 ug/1(acute impacts). Due to analytical issues, all TRC values
reported below 50 ug/1 are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal: TRC limits have
been reviewed in the attached WLA and have been found to be protective.No changes are proposed at
any flow tier.
The current ammonia permit limits are based on ammonia toxicity. The ammonia limits have been
reviewed in the attached WLA for toxicity and have been found to be protective.No changes are
proposed at any flow tier.
Page 5 of 13

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/z detection limit for"less than"values; and 4) streamflows used for dilution
consideration based on 15A NCAC 2B.0206. Effective April 6,2016,NC began implementation of
dissolved metals criteria in the RPA process in accordance with guidance titled NPDES Implementation of
Instream Dissolved Metals Standards, dated June 10,2016.
A reasonable potential analysis was conducted on effluent toxicant data collected between June 2018 and
October 2022. 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 Monitoring. The following parameters will receive a water quality-based
effluent limit(WQBEL) since they demonstrated a reasonable potential to exceed applicable
water quality standards/criteria: None
• Monitoring Only. The following parameters will receive a monitor-only requirement since they
did not demonstrate reasonable potential to exceed applicable water quality standards/criteria,
but the maximum predicted concentration was>50%of the allowable concentration: None
• 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: Total Arsenic, Total Cadmium, Total Chromium, Total Copper,Total Cyanide,
Total Lead, Total Nickel,Total Selenium, Total Silver,Total Zinc,Nitrate
• 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
o The following parameters will not receive a limit or monitoring, since they did not
demonstrate reasonable potential to exceed applicable water quality standards/criteria and
the maximum predicted concentration was<50%of the allowable concentration: Total
Beryllium, Chlorides, Total Phenolic Compounds
As the Mayodan WWTP discharges 1.4 miles upstream of WS waters,WS-V standards were considered
during the RPA. Effluent hardness was not reported at levels greater than 100 mg/L during the period
reviewed.No chlorinated phenolic compounds were detected in the 3 submitted effluent pollutant scans.
Total Dissolved Solids were not reported at concentrations greater than 500 mg/L in the 3 submitted
effluent pollutant scans.
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.
Page 6 of 13

Toxicity Testing Limitations
Permit limits and monitoring requirements for Whole Effluent Toxicity(WET)have been established in
accordance with Division guidance(per WET Memo, 8/2/1999). Per WET guidance, all NPDES permits
issued to Major facilities or any facility discharging"complex"wastewater(contains anything other than
domestic waste)will contain appropriate WET limits and monitoring requirements,with several
exceptions. The State has received prior EPA approval to use an Alternative WET Test Procedure in
NPDES permits,using single concentration screening tests,with multiple dilution follow-up upon a test
failure.
Describe proposed toxicity test requirement: This is a Major POTW, and a chronic WET limit at 5%
effluent at 2.5 MGD, 6%effluent at 3.0 MGD and 9%at 4.5 MGD will continue on a quarterly frequency.
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/1)will
receive an MMP requirement. Industrials are evaluated on a case-by-case basis, depending if mercury is a
pollutant of concern. Effluent limits may also be added if annual average effluent concentrations exceed
the WQBEL value(based on the NC WQS of 12 ng/1) and/or if any individual value exceeds a TBEL
value of 47 ng/l.
Table 3. Mercury Effluent Data Summary
2018 2019 2020 2021 2022
#of Samples 2 4 5 8 9
Annual Average Conc. n /L 2.2 4.6 2.6 4.0 3.4
Maximum Conc.,n /L 2.8 8.4 8.0 11.0 12.4
TBEL,n /L 47
WQBEL,n /L 244.3
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 mercury
limit is required. Since the facility is a 2.0 MGD facility and reported quantifiable levels of mercury(> 1
ng/1),the mercury minimization plan(MMP) special condition has been maintained.
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation
within this permit: NA
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: As required by Session
Law 2018-5, Senate Bill 99, Section 13.1(r), every applicant shall submit documentation of any additional
pollutants for which there are certified methods with the permit application if their discharge is
anticipated via a Chemical Addendum to NPDES Application table. As an attachment to the permit
application,the Town informed the Division that no monitoring for additional pollutants has been
conducted(see attached chemical addendum)and therefore no additional pollutants of concern have been
identified.
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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 mg1l
BOD51TSS for Monthly Average, and 45 mg/Z for BOD51TSS 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; overall 85%removal was
achieved for the period reviewed. Instances were observed where 85%TSS removal was not achieved for
a given month. However,upon further review,these instances corresponded with lower levels of influent
TSS were received at the plant.
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): YES
If YES, confirm that antibacksliding provisions are not violated.• Based on the reasonable potential
analysis(RPA) showing no reasonable potential to violate state water quality standards,the limits and
monitoring requirements for total chromium, and monitoring requirements for total copper and total silver
have been removed from the permit. Based on Mercury TMDL evaluation showing no annual average
mercury concentration exceeding the WQBEL, and no individual mercury sample exceeding the TBEL at
any flow tier,the total mercury limit and monitoring requirements have been removed from the permit.
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 213.0500;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
Page 8 of 13

Professional Judgement(BPJ). Per US EPA(Interim Guidance, 1996),monitoring requirements are not
considered effluent limitations under Section 402(o)of the Clean Water Act, and therefore anti-
backsliding prohibitions would not be triggered by reductions in monitoring frequencies.
For instream monitoring,refer to Section 4.
The Town has requested 2/week monitoring for BOD, ammonia, TSS and fecal coliform based on 2012
DWR Guidance Regarding the Reduction of Monitoring Frequencies in NPDES Permits for
Exceptionally Performing Facilities be maintained. The last three years of the facility's data for these
parameters have been reviewed in accordance with the criteria outlined in the guidance. Based on this
review, 2/week monitoring frequency has been applied for BOD, summer ammonia, and TSS. The permit
is not limited for winter ammonia. Fecal coliform did not meet the criteria identified in the 2012
guidance; monitoring for Fecal Coliform is maintained at 3/week. Weekly monitoring for winter ammonia
has been maintained at the 2.5 MGD flow tier in accordance with 15A NCAC 02B .0508. As 15A NCAC
02B .0508 requires 3/week monitoring for ammonia for Grade IV facilities,winter ammonia monitoring
has been revised from weekly to 3/week at the 3.0 MGD flow tier. Upon expansion above 2.5 MGD to
either the 3.0 MGD or 4.5 MGD flow tiers,monitoring frequencies for BOD, ammonia and TSS will
revert to the monitoring frequencies identified under 15A NCAC 02B .0508. After six(6) consecutive
months of sampling at the increased flow tier,the Permittee may request a reduction in the monitoring
frequency to twice per week sampling for any of the three parameters (BOD5, TSS, and ammonia)for
which no effluent permit limit violations have occurred.
As the Mayodan WWTP accepts influent wastewater from an industrial facility that is a potential source
of 1,4-dioxane(Strum,Ruger&Company-Metals Finisher)via the approved pretreatment program, as
no additional sampling has been conducted for 1,4-dioxane at this facility as identified in the chemical
addendum submitted by the Town, and as the facility discharges approximately 1.4 miles upstream of
waters designated as WS-V, 2/year effluent monitoring for 1,4-dioxane as well as a 1,4-dioxane reopener
condition have been added to the permit.
To identify PFAS contamination in waters classified as Water Supply(WS)waters,monitoring
requirements are to be implemented in permits with pretreatment programs that discharge to WS waters.
As the Mayodan WWTP has a pretreatment program and discharges treated wastewater approximately 1.4
miles upstream of waters designated as WS-V,monitoring of PFAS chemicals will be added to the permit
at a frequency of quarterly. Since an EPA method for sampling and analyzing PFAS in wastewater is not
currently available,the PFAS sampling requirement in the Permit includes a compliance schedule which
delays the effective date of this requirement until the first full calendar quarter beginning 6 months after
EPA has a final wastewater method in 40 CFR136 published in the Federal Register to allow time for
laboratories to become certified in the new method. This date may be extended upon request and if there
are no NC-certified labs.
11. Electronic Reporting Requirements
The US EPA NPDES Electronic Reporting Rule was finalized on December 21, 2015. Effective
December 21, 2016,NPDES regulated facilities are required to submit Discharge Monitoring Reports
(DMRs) electronically. While NPDES regulated facilities would initially be required to submit additional
NPDES reports electronically effective December 21, 2020, EPA extended this deadline from December
21,2020,to December 21,2025. The current compliance date, effective January 4,2021,was extended as
a final regulation change published in the November 2, 2020 Federal Register. This permit contains the
requirements for electronic reporting, consistent with Federal requirements.
Page 9 of 13

12.Summary of Proposed Permitting Actions:
Table 4. Current Permit Conditions and Proposed Changes Outfall 001
Parameter Current Permit Proposed Change Basis for Condition/Change
Flow MA 2.5 MGD with expansion No change to 2.5 MGD 15A NCAC 213 .0505; facility
tiers 3.0 MGD and 4.5 MGD; or 3.0 MGD tiers; design capacity is 4.5 MGD so
3.0 MGD flow tier activated 80%is not necessary for tier
upon annual average effluent 4.5 MGD flow tier activation-90%applied to
flow exceeding 2.0 MGD activated upon annual allow for 3.0 MGD flow tier to
(80%of 2.5 MGD tier); average effluent flow be active for reasonable amount
4.5 MGD flow tier activated exceeding 2.7 MGD of time
upon annual average effluent (90%of 3.0 MGD tier)
flow exceeding 2.4 MGD
(80%of 3.0 MGD tier)
BOD5 All flow tiers: No change to limits for TBEL. 1994 empirical model
MA 30.0 mg/L all tiers;No change to results; 2012 DWR Guidance
WA 45.0 mg/L monitoring requirements Regarding the Reduction of
Monitor and report 2/Week for 2.5 MGD; Monitoring Frequencies in
3.0 MGD and 4.5 MGD NPDES Permits for
tiers: Exceptionally Performing
Monitor and report Facilities
Daily;
Expanded flow tiers:
If after 6 months no
limit violations, Town
may request 2/week
monitoring frequency
NH3-N 2.5 MGD tier: No change to limits for WQBEL. 1994 empirical model
Summer: all tiers;No change to results;verified with 2023 WLA
MA 16.0 mg/1 monitoring requirements based on ammonia toxicity; 2012
WA 35.0 mg/1 for 2.5 MGD; DWR Guidance Regarding the
Monitor and report 2/Week 3.0 MGD tier: Reduction of Monitoring
Winter: Monitor and report Frequencies in NPDES Permits
Monitor and report Weekly; Daily during winter and for Exceptionally Performing
3.0 MGD tier: 3/Week during winter; Facilities; 15A NCAC 02B
Summer: 4.5 MGD tier: .0508
MA 14.0 mg/1
WA 35.0 mg/1 Monitor and report
Monitor and report 2/Week Daily;
Winter: Expanded flow tiers:
Monitor and report Weekly; If after 6 months no
4.5 MGD tier: limit violations, Town
Summer: may request 2/week
MA 9.0 mg/1 monitoring frequency
WA 27.0 mg/1
Monitor and report 2/Week
Winter:
MA 31.5 mg/1
WA 35.0 mg/1
Monitor and report 2/Week
Page 10 of 13

TSS All flow tiers: No change to limits for TBEL. 1994 empirical model
MA 30.0 mg/L all tiers;No change to results; 2012 DWR Guidance
WA 45.0 mg/L monitoring requirements Regarding the Reduction of
Monitor and report 2/Week for 2.5 MGD; Monitoring Frequencies in
3.0 MGD and 4.5 MGD NPDES Permits for
tiers: Exceptionally Performing
Monitor and report Facilities; 15A NCAC 02B
Daily; .0508
Expanded flow tiers:
If after 6 months no
limit violations, Town
may request 2/week
monitoring frequency
Fecal All flow tiers: No change WQBEL. State WQ standard,
coliform MA 200/100ml 15A NCAC 2B .0200; Surface
WA 400/100ml; Water Monitoring, 15A NCAC
2.5 MGD flow tier: 2B. 0500;Evaluation of MFR-
Monitor and report 3/Week; criteria not met
3.0 MGD and 4.5 MGD tiers:
Monitor and report Dail
Temperature 2.5 MGD flow tier: No change Surface Water Monitoring, 15A
Monitor and report 3/Week NCAC 2B. 0508
3.0 MGD and 4.5 MGD tiers:
Monitor and report Dail
DO 2.5 MGD flow tier: No change 1994 empirical model results;
Monitor and report 3/Week Surface Water Monitoring, 15A
3.0 MGD and 4.5 MGD tiers: NCAC 2B. 0508
Monitor and report Daily
pH All flow tiers: No change WQBEL. State WQ standard,
6-9 SU; 15A NCAC 2B .0200; 15A
2.5 MGD flow tier: NCAC 02B .0500
Monitor and report 3/Week
3.0 MGD and 4.5 MGD tiers:
Monitor and report Daily
Conductivity 2.5 MGD flow tier: No change Surface Water Monitoring, 15A
Monitor and report 3/Week; NCAC 2B. 0500; PT program
3.0 MGD and 4.5 MGD tiers:
Monitor and report Daily
Total All flow tiers: No change WQBEL. 2023 WLA. Surface
Residual DM 28 ug/L; Water Monitoring, 15A NCAC
Chlorine 2.5 MGD flow tier: 2B. 0500
Monitor and report 3/Week;
3.0 MGD and 4.5 MGD tiers:
Monitor and report Dail
TKN No requirement All flow tiers: For calculation of TN
Monitor and Report
Monthly
NO2+NO3 No requirement All flow tiers: For calculation of TN
Monitor and Report
Monthly
Page 11 of 13

Total All flow tiers: No change Surface Water Monitoring, 15A
Nitrogen Monitor and Report Monthly NCAC 2B. 0500
Total All flow tiers: No change Surface Water Monitoring, 15A
Phosphorus Monitor and Report Monthly NCAC 2B. 0500
Total Copper All flow tiers: Remove requirements Based on results of Reasonable
Monitor and Report Quarterly Potential Analysis(RPA).
No RP,Predicted Max<50%of
Allowable Cw-No Monitoring
required at all tiers
Total 2.5 MGD tier: Remove requirements Based on results of Reasonable
Chromium Monitor and report Quarterly Potential Analysis(RPA).
No monitoring required if all
3.0 MGD tier: Total Chromium samples are<5
MA 856 ug/l µg/L or Pred. max for Total Cr is
DM 14,500 ug/1 <allowable Cw for Cr VI.
Monitor and report Monthly
4.5 MGD tier:
MA 587 ug/1
DM 10,000 ug/1
Monitor and report Monthly
Total Silver All flow tiers: Remove requirements Based on results of Reasonable
Monitor and Report Quarterly Potential Analysis(RPA).
All values non-detect< 1 ug/L
and<0.25 ug/L;No monitoring
required
Total All flow tiers: Remove requirements Based on Mercury TMDL
Mercury AA 47 ng/L Evaluation;no annual average
Monitor and Report Quarterly mercury concentration exceeded
the WQBEL, and no individual
mercury sample exceeded the
TBEL at any flow tier
Total No requirement All flow tiers: Hardness-dependent dissolved
Hardness Quarterly monitoring metals water quality standards
Upstream and in approved in 2016
Effluent
1,4-dioxane No requirement All flow tiers: Based on PT Program—
Add 2/year effluent industrial facility linked to 1,4-
monitoring and reopener dioxane
condition
All flow tiers: Evaluation of PFAS
Add quarterly contribution: pretreatment
PFAS No requirement facility; Implementation delayed
monitoring with delayed until after EPA certified method
implementation becomes available.
Toxicity Test Chronic limit, 5%effluent @ No change WQBEL. No toxics in toxic
2.5 MGD, 6%effluent @ 3.0 amounts. 15A NCAC 213.0200
and 15A NCAC 213.0500
Page 12 of 13

MGD and 9%effluent @ 4.5
MGD
Effluent Three times per permit cycle No change; conducted in 40 CFR 122
Pollutant 2025,2026,2027
Scan
Mercury MMP Special Condition No change; MMP WQBEL. Consistent with 2012
Minimization maintained Statewide Mercury TMDL
Plan(MMP) Implementation.
Electronic No requirement Electronic Reporting In accordance with EPA
Reporting Special Condition Electronic Reporting Rule 2015.
MGD—Million gallons per day,MA- Monthly Average,WA—Weekly Average,DM—Daily Max
13. Public Notice Schedule:
Permit to Public Notice: 05/17/2023
Per 15A NCAC 2H .0109 & .0111, The Division will receive comments for a period of 30 days following
the publication date of the public notice.Any request for a public hearing shall be submitted to the
Director within the 30 days comment period indicating the interest of the party filing such request and the
reasons why a hearing is warranted.
14. NPDES Division Contact
If you have any questions regarding any of the above information or on the attached permit,please
contact Nick Coco at(919) 707-3609 or via email at nick.cocogdeq.nc.gov.
15. Fact Sheet Addendum (if applicable):
The draft was submitted to the Town of Mayodan, EPA Region IV, and the Division's Winston-Salem
Regional Office,Aquatic Toxicology Branch, Operator Certification Program and Pretreatment Unit for
review. The Town of Mayodan provided comment to the Division on May 22, 2023 noting an error in the
monitoring frequency for ammonia during the winter months. The permit set monitoring for ammonia
winter ammonia at 2/week based on the 2012 DWR Guidance Regarding the Reduction of Monitoring
Frequencies in NPDES Permits for Exceptionally Performing Facilities. However,this is actually a more
frequent sampling regimen than required by rule for winter ammonia at this facility. Per permittee
request,the winter ammonia monitoring has been reverted to weekly.
Were there any changes made since the Draft Permit was public noticed(Yes/No):YES
If Yes, list changes and their basis below:
• Per Permittee request;the monitoring of winter ammonia has been corrected to weekly to reflect
15A NCAC 02B .0508.
16. Fact Sheet Attachments (if applicable):
• RPA Spreadsheet Summary
• NPDES Implementation of Instream Dissolved Metals Standards—Freshwater Standards
• NH3/TRC WLA Calculations
• BOD&TSS Removal Rate Calculations
• Mercury TMDL Calculations
• Monitoring Frequency Reduction Evaluation
• Pretreatment Information Request Form
• WET Testing and Self-Monitoring Summary
• Compliance Inspection Report
• Chemical Addendum
Page 13 of 13

Coco, Nick A
From: Coco, Nick A
Sent: Monday, May 22, 2023 11:57 AM
To: Blackwell, Nadine
Cc: Patterson, Kathleen A;Jamie Whitten; Montebello, Michael J
Subject: RE: [External] Re: Draft Permit Mayodan WWTP, NPDES Permit Number NC0021873, SIC Code 4952
Follow Up Flag: Follow up
Flag Status: Flagged
You are correct.Thank you for bringing this to my attention.The permit currently notes a 2/week monitoring frequency
for winter ammonia at 2.5 MGD.This should instead state Weekly. I will correct this.
Thanks,
Nick Coco, PE (he/him/his)
Engineer 111
NPDES Municipal Permitting Unit
NC DEQ/Division of Water Resources/Water Quality Permitting
Office: [phone]
[e-mail]
Physical Address: 512 North Salisbury St.,Raleigh, NC, 27604
Mailing Address: 1617 Mail Service Center, Raleigh, NC, 27699-1617
D- E
tm' �
NORTH CAROLINA
Department of Environmental Quality
Email correspondence to and from this address is subject to the North
Carolina Public Records Law and may be disclosed to third parties.
From: Blackwell, Nadine<[e-mail]>
Sent: Monday, May 22, 2023 11:46 AM
To: Coco, Nick A<[e-mail]>
Cc: Patterson, Kathleen A<[e-mail]>;Jamie Whitten <[e-mail]>; Montebello,
Michael J <[e-mail]>
Subject: Re: [External] Re: Draft Permit Mayodan WWTP, NPDES Permit Number NC0021873, SIC Code 4952
CAUTION: External email. Do not click links or open attachments unless verified. Report suspicious emails with the Report Message
button located on your Outlook menu bar on the Home tab.
Thank you for the clarification. I think the Permit needs to be amended to reflect the weekly monitoring during the
winter months?
i

On Mon, May 22, 2023 at 11:33 AM Coco, Nick A<[e-mail]>wrote:
Hi Nadine,
Thanks for reaching out. Currently(at the 2.5 MGD tier), the Mayodan WWTP is a Grade III facility per 15A NCAC 08G
.0302. In the winter at the 2.5 MGD flow tier, ammonia does not have a limit. Per 15A NCAC 02B .0508, Grade III
facilities that are effluent limited for ammonia (meaning not water-quality limited) are only required to conduct
monthly monitoring for ammonia.The Mayodan WWTP did demonstrate compliance with guidance criteria for
reduction in monitoring frequency to 2/week, but since that would be more frequent than what was required, we have
maintained the weekly monitoring of ammonia in the winter at the 2.5 MGD flow tier.That being said,the Town may
always conduct more sampling than what is required in the permit.
Please let me know if you have any other questions.
Thanks,
Nick Coco, PE (he/him/his)
Engineer///
NPDES Municipal Permitting Unit
NC DEQ/Division of Water Resources/Water Quality Permitting
Office: [phone]
[e-mail]
Physical Address: 512 North Salisbury St.,Raleigh, NC, 27604
Mailing Address: 1617 Mail Service Center, Raleigh, NC, 27699-1617
DE
NORTH CAROLINA -
Department of Environmental Quality
Email correspondence to and from this address is subject to the North
Carolina Public Records Law and may be disclosed to third parties.
z

From: Blackwell, Nadine<[e-mail]>
Sent: Monday, May 22, 2023 8:35 AM
To: Coco, Nick A<[e-mail]>
Cc: Patterson, Kathleen A<[e-mail]>;Jamie Whitten <[e-mail]>; Montebello,
Michael J <[e-mail]>
Subject: Re: [External] Re: Draft Permit Mayodan WWTP, NPDES Permit Number NC0021873, SIC Code 4952
CAUTION: External email. Do not click links or open attachments unless verified. Report suspicious emails with the Report Message
button located on your Outlook menu bar on the Home tab.
Good morning Nick,
In reviewing the draft Permit,for the 1st tier Permit (2.5 MGD) should the monitoring frequency for the winter NH3 be
weekly or 2/week?
On Fri, May 19, 2023 at 9:48 AM Coco, Nick A<[e-mail]>wrote:
Hi Nadine,
Thank you for letting me know so quickly! I must have accidentally copied the wrong link. Please see the appropriate
links below:
Draft Permit: https://edocs.deq.nc.gov/WaterResources/DocView.aspx?id=2789040&dbid=0&repo=WaterResources
NPDES Standard Conditions: https://bit.ly/3k5NFaL
Draft Fact Sheet:
https://edocs.deq.nc.gov/WaterResources/DocView.aspx?id=2801460&dbid=0&repo=WaterResources
Thanks,
3

Nick Coco, PE (he/him/his)
Engineer///
NPDES Municipal Permitting Unit
NC DEQ/Division of Water Resources/Water Quality Permitting
Office: [phone]
[e-mail]
Physical Address: 512 North Salisbury St.,Raleigh, NC, 27604
Mailing Address: 1617 Mail Service Center, Raleigh, NC, 27699-1617
D- E Qk
NORTH CAROLINA
Department of Environmental Duality
Email correspondence to and from this address is subject to the North
Carolina Public Records Law and may be disclosed to third parties.
From: Blackwell, Nadine<[e-mail]>
Sent: Friday, May 19, 2023 9:45 AM
To: Coco, Nick A<[e-mail]>
Cc: Patterson, Kathleen A<[e-mail]>;Jamie Whitten <[e-mail]>; Montebello,
Michael J <[e-mail]>
Subject: [External] Re: Draft Permit Mayodan WWTP, NPDES Permit Number NC0021873, SIC Code 4952
CAUTION: External email. Do not click links or open attachments unless verified. Report suspicious emails with the Report
Message button located on your Outlook menu bar on the Home tab.
Nick,
This is the link to McAlpine Creek WWTP.
4

On Fri, May 19, 2023 at 9:19 AM Coco, Nick A<[e-mail]>wrote:
Hi Kathleen,
I hope all is well
Please see the following links to review the draft permit and cover letter and draft fact sheet for NPDES permit
NC0021873 for the Mayodan WWTP. I have also provided a link to the NPDES Standard Conditions for your
reference.The Town has a 30-day period ending on 6/19/2023 to comment, ask questions, or request an extension
to review this draft permit. Please contact me with any comments you might have.
Draft Permit: https://edocs.deg.nc.gov/WaterResources/DocView.aspx?id=2789035&dbid=0&repo=WaterResources
NPDES Standard Conditions: https://bit.IV/3k5NFaL
Draft Fact Sheet:
https://edocs.deg.nc.gov/WaterResources/DocView.aspx?id=2801459&dbid=0&repo=WaterResources
Thanks, and have a nice day.
Best,
Nick Coco, PE (he/him/his)
Engineer 111
NPDES Municipal Permitting Unit
NC DEQ/Division of Water Resources/Water Quality Permitting
Office: [phone]
[e-mail]
Physical Address: 512 North Salisbury St.,Raleigh, NC, 27604
Mailing Address: 1617 Mail Service Center, Raleigh, NC, 27699-1617
5

�
vc���D- E
NORTH CAROLINA C111-1)
Department of Environmental Duality
Email correspondence to and from this address is subject to the North
Carolina Public Records Law and may be disclosed to third parties.
Email correspondence to and from this address may be subject to the North Carolina Public Records Law and may be disclosed to third parties by an
authorized state official.
6

Rockingham Now
Advertising Affidavit Account Number
4019534
Date
May 17,2023
NCDEQ-DIVISION OF WATER RESOURCES
1617 MAIL SERVICE CENTER
RALEIGH,INC 27699-1617
PO Number Order Category Description
0000834832 Legal Notices Public Notice North Carolina Environmental Management CommissionlNPDES Unit 1617 Mail:
Publisher of the
Rockingham Now
Before the undersigned,a Notary Public duly commissioned,qualified,and authorized by
law to administer oaths,personally appeared the Publisher's Representative who by being
duly sworn deposes and says:that he/she is authorized to make this affidavit and sworn
statement;that the notice or other legal advertisement,a copy of which is attached hereto,
was published in the Rockingham Now on the following dates:
05/17/2023
and that the said newspaper in which such notice,paper document,or legal advertisement
was published,was at the time of each and every such publication,a newspaper meeting all
the requirements and qualifications of Section 1-597 of the General Statutes of North
Carolina.
Billing Representative
Sworn to and subscribed before me the 17th ay o ay,202 r
(Notary, b
Kelly Ann Johnson
State of Virginia NOTARY PUBLIC
Commonwealth of Virginia
County of Hanover Registration No.8004299
My commission expires: My Comm.Ex ch 31,2026
THIS IS NOT A BILL. PLEASE PAY FROM INVOICE. THANK YOU

Public Notice
North Carolina Environmental Management Commission/NPDES Unit
1617 Mail Service Center
Raleigh,NC 27699.1617
Notice of Intent to Issue a NPDES Wastewater Permit NCO021873
Mayodan WWTP The North Carolina Environmental Management Commis-
sion proposes to issue a NPDES wastewater discharge permit to the
person(s)listed below. Written comments regarding the proposed permit
will be accepted until 30 days after the publish date of this notice.The Di-
rector of the NC Division of Water Resources(DWR) may hold a public
hearing should there be a significant degree of public interest. Please
mail comments and/or information requests to DWR at the above ad-
dress.Interested persons may visit the DWR at 512 N.Salisbury Street,Ra-
leigh,NC 27604 to review the information on file. Additional information
on NPDES permits and this notice may be found on our website:https://d
eq.nc.gov/public-notices-hearings,or by calling(919)707-3601. The Town
of Mayodan(210 W Main Street,Mayodan,NC 27027]has requested re-
newal of NPDES permit NCO021873 for its Mayodan WWTP, located in
Rockingham County.This permitted facility discharges treated municipal
and industrial wastewater to the Mayo River,a Class C water in the Roa-
noke River Basin.Currently ammonia,fecal coliform,total residual chlor-
ine and pH are water quality limited.This discharge may affect future allo-
cations in this segment of the Mayo River.

Rockingham Now
Advertising Affidavit Account Number
4019534
Date
May 17,2023
NCDEQ-DIVISION OF WATER RESOURCES
1617 MAIL SERVICE CENTER
RALEIGH,INC 27699-1617
PO Number Order Category Description
0000834832 Legal Notices Public Notice North Carolina Environmental Management CommissionlNPDES Unit 1617 Mail:
Publisher of the
Rockingham Now
Before the undersigned,a Notary Public duly commissioned,qualified,and authorized by
law to administer oaths,personally appeared the Publisher's Representative who by being
duly sworn deposes and says:that he/she is authorized to make this affidavit and sworn
statement;that the notice or other legal advertisement,a copy of which is attached hereto,
was published in the Rockingham Now on the following dates:
05/17/2023
and that the said newspaper in which such notice,paper document,or legal advertisement
was published,was at the time of each and every such publication,a newspaper meeting all
the requirements and qualifications of Section 1-597 of the General Statutes of North
Carolina.
Billing Representative
Sworn to and subscribed before me the 17th ay o ay,202 r
(Notary, b
Kelly Ann Johnson
State of Virginia NOTARY PUBLIC
Commonwealth of Virginia
County of Hanover Registration No.8004299
My commission expires: My Comm.Ex ch 31,2026
THIS IS NOT A BILL. PLEASE PAY FROM INVOICE. THANK YOU

Public Notice
North Carolina Environmental Management Commission/NPDES Unit
1617 Mail Service Center
Raleigh,NC 27699.1617
Notice of Intent to Issue a NPDES Wastewater Permit NCO021873
Mayodan WWTP The North Carolina Environmental Management Commis-
sion proposes to issue a NPDES wastewater discharge permit to the
person(s)listed below. Written comments regarding the proposed permit
will be accepted until 30 days after the publish date of this notice.The Di-
rector of the NC Division of Water Resources(DWR) may hold a public
hearing should there be a significant degree of public interest. Please
mail comments and/or information requests to DWR at the above ad-
dress.Interested persons may visit the DWR at 512 N.Salisbury Street,Ra-
leigh,NC 27604 to review the information on file. Additional information
on NPDES permits and this notice may be found on our website:https://d
eq.nc.gov/public-notices-hearings,or by calling(919)707-3601. The Town
of Mayodan(210 W Main Street,Mayodan,NC 27027]has requested re-
newal of NPDES permit NCO021873 for its Mayodan WWTP, located in
Rockingham County.This permitted facility discharges treated municipal
and industrial wastewater to the Mayo River,a Class C water in the Roa-
noke River Basin.Currently ammonia,fecal coliform,total residual chlor-
ine and pH are water quality limited.This discharge may affect future allo-
cations in this segment of the Mayo River.

Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM DATA POINTS = 58
REQUIRED DATA ENTRY
Table 1. Project Information Table 2. Parameters of Concern
❑ CHECK IF HQW OR ORW WQS Name WQs Type Chronic Modifier Acute PQL Units
Facility Name Mayodan WWTP Par01 Arsenic Aquactic Life C 150 FW 340 ug/L
WWTP/WTP Class III Par02 Arsenic Human Health C 10 HH/WS N/A ug/L
Water Supply
NPDES Permit NCO021873 Par03 Beryllium Aquatic Life NC 6.5 FW 65 ug/L
Outfall 001 Par04 Cadmium Aquatic Life NC 0.5899 FW 3.2396 ug/L
Flow, Qw (MGD) 2.500 Par05 Chlorides Water Supply NC 250 WS mg/L
Receiving Stream Mayo River Par06 Chlorinated Phenolic Compounds Water Supply NC 1 A ug/L
HUC Number 03010103 Par07 Total Phenolic Compounds Aquatic Life NC 300 A ug/L
Stream Class C Par08 Chromium III Aquatic Life NC 117.7325 FW 905.0818 ug/L
❑✓ Apply WS Hardness WQC Par09 Chromium VI Aquatic Life NC 11 FW 16 pg/L
7Q10s (cfs) 75.000 Par10 Chromium, Total Aquatic Life NC N/A FW N/A pg/L
7Q10w (cfs) 131.00 Par11 Copper Aquatic Life NC 7.8806 FW 10.4720 ug/L
30Q2 (cfs) 150.00 Par12 Cyanide Aquatic Life NC 5 FW 22 10 ug/L
QA(cfs) 362.00 Par13 Fluoride Aquatic Life NC 1,800 FW ug/L
1Q10s (cfs) 111 61.34 Par14 Lead Aquatic Life NC 2.9416 FW 75.4871 ug/L
Effluent Hardness 45.9 mg/L (Avg) Par15 Mercury Aquatic Life NC 12 FW 0.5 ng/L
------------- -------------------
Upstream Hardness 20.47 mg/L (Avg) Par16 Molybdenum Water Supply NC 160 WS ug/L
-------------Combined Hardness Hardness Chronic 25 mg/L Par17 Nickel Aquatic Life NC 37.2313 FW 335.2087 pg/L
------------- ---- ------------
Combined Hardness Acute 25 mg/L Par18 Nickel Water Supply NC 25.0000 WS N/A pg/L
Data Source(s) As the facility discharges approximately 1.4 miles Par19 Selenium Aquatic Life NC 5 FW 56 ug/L
❑ CHECK TO APPLY MODEL above a WS-V water, WS standards have been Par20 Silver Aquatic Life NC 0.06 FW 0.2964 ug/L
considered. Nitrate + Nitrite used as conservative
estimate for Nitrate. Par21 Zinc Aquatic Life NC 126.7335 FW 125.7052 ug/L
Par22 Nitrate Water Supply NC 10 WS mg/L
Par23
Par24
21873 RPA, input
5/3/2023

Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM DATA POINTS = 58
REQUIRED DATA ENTRY
Table 1. Project Information Table 2. Parameters of Concern
❑ CHECK IF HQW OR ORW WQS Name WQs Type Chronic Modifier Acute PQL Units
Facility Name Mayodan WWTP Par01 Arsenic Aquactic Life C 150 FW 340 ug/L
WWTP/WTP Class III Par02 Arsenic Human Health C 10 HH/WS N/A ug/L
Water Supply
NPDES Permit NCO021873 Par03 Beryllium Aquatic Life NC 6.5 FW 65 ug/L
Outfall 001 Par04 Cadmium Aquatic Life NC 0.5899 FW 3.2396 ug/L
Flow, Qw (MGD) 4.500 Par05 Chlorides Water Supply NC 250 WS mg/L
Receiving Stream Mayo River Par06 Chlorinated Phenolic Compounds Water Supply NC 1 A ug/L
HUC Number 03010103 Par07 Total Phenolic Compounds Aquatic Life NC 300 A ug/L
Stream Class C Par08 Chromium III Aquatic Life NC 117.7325 FW 905.0818 ug/L
❑✓ Apply WS Hardness WQC Par09 Chromium VI Aquatic Life NC 11 FW 16 pg/L
7Q10s (cfs) 75.000 Par10 Chromium, Total Aquatic Life NC N/A FW N/A pg/L
7Q10w (cfs) 131.00 Par11 Copper Aquatic Life NC 7.8806 FW 10.4720 ug/L
30Q2 (cfs) 150.00 Par12 Cyanide Aquatic Life NC 5 FW 22 10 ug/L
QA(cfs) 362.00 Par13 Fluoride Aquatic Life NC 1,800 FW ug/L
1Q10s (cfs) 111 61.34 Par14 Lead Aquatic Life NC 2.9416 FW 75.4871 ug/L
Effluent Hardness 45.9 mg/L (Avg) Par15 Mercury Aquatic Life NC 12 FW 0.5 ng/L
------------- -------------------
Upstream Hardness 20.47 mg/L (Avg) Par16 Molybdenum Water Supply NC 160 WS ug/L
-------------Combined Hardness Hardness Chronic 25 mg/L Par17 Nickel Aquatic Life NC 37.2313 FW 335.2087 pg/L
------------- ---- ------------
Combined Hardness Acute 25 mg/L Par18 Nickel Water Supply NC 25.0000 WS N/A pg/L
Data Source(s) As the facility discharges approximately 1.4 miles Par19 Selenium Aquatic Life NC 5 FW 56 ug/L
❑ CHECK TO APPLY MODEL above a WS-V water, WS standards have been Par20 Silver Aquatic Life NC 0.06 FW 0.2964 ug/L
considered. Nitrate + Nitrite used as conservative
estimate for Nitrate. Par21 Zinc Aquatic Life NC 126.7335 FW 125.7052 ug/L
Par22 Nitrate Water Supply NC 10 WS mg/L
Par23
Par24
21873 RPA, input
5/3/2023

REASONABLE POTENTIAL ANALYSIS
H1 H2 Use"PASTE SPECIAL Use"PASTE SPECIAL
Effluent Hardness Values"then"COPY" Upstream Hardness Values"then"COPY"
Maximum data .Maximum data
points=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 9/4/2018 51 51 Std Dev. 9.1473 1 9/4/2018 20 20 Std Dev. 6.3749
2 12/3/2018 57 57 Mean 45.9000 2 12/4/2018 20 20 Mean 20.4706
3 3/5/2019 37 37 C.V. 0.1993 3 3/5/2019 12 12 C.V. 0.3114
4 6/18/2019 59 59 n 20 4 6/18/2019 27 27 n 17
5 9/3/2019 61 61 10th Per value 34.70 mg/L 5 9/3/2019 19 19 10th Per value 14.00 mg/L
6 12/3/2019 35 35 Average Value 45.90 mg/L 6 12/3/2019 14 14 Average Value 20.47 mg/L
7 3/3/2020 50 50 Max. Value 61.00 mg/L 7 6/2/2020 18 18 Max. Value 40.00 mg/L
8 6/2/2020 32 32 8 9/1/2020 22 22
9 9/1/2020 42 42 9 12/1/2020 14 14
10 12/1/2020 38 38 10 3/3/2021 16 16
11 3/3/2021 46 46 11 6/1/2021 20 20
12 6/1/2021 51 51 12 9/7/2021 24 24
13 6/8/2021 55 55 13 12/7/2021 24 24
14 9/7/2021 57 57 14 4/20/2022 40 40
15 12/7/2021 44 44 15 5/31/2022 18 18
16 3/1/2022 41 41 16 9/7/2022 18 18
17 4/20/2022 48 48 17 12/6/2022 22 22
18 5/31/2022 40 40 18
19 9/7/2022 30 30 19
20 12/6/2022 44 44 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
21873 RPA, data
- 1 - 5/3/2023

REASONABLE POTENTIAL ANALYSIS
Par01 & Par02
Use"PASTE SPECIAL
Arsenic Values"then"COPY"
Maximum data
points=58
Date Data BDL=1/2DL Results
1 9/25/2018 < 5 2.5 Std Dev. 0.7434
2 12/5/2018 < 5 2.5 Mean 1.5526
3 3/12/2019 < 5 2.5 C.V. 0.4788
4 6/11/2019 < 5 2.5 n 19
5 9/11/2019 < 5 2.5
6 12/10/2019 < 5 2.5 Mult Factor= 1.31
7 3/10/2020 < 5 2.5 Max. Value 2.5 ug/L
8 6/9/2020 < 2 1 Max. Pred Cw 3.3 ug/L
9 9/8/2020 < 2 1
10 12/1/2020 < 2 1
11 3/2/2021 < 2 1
12 6/8/2021 < 2 1
13 6/9/2021 < 2 1
14 9/14/2021 < 2 1
15 12/8/2021 < 2 1
16 3/1/2022 < 2 1
17 6/8/2022 < 2 1
18 9/20/2022 < 2 1
19 12/13/2022 < 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
21873 RPA, data
-2 - 5/3/2023

REASONABLE POTENTIAL ANALYSIS
Par03 Par04
Use"PASTE SPECIAL Use"PASTE SPECIAL
Beryllium Values"then"COPY" Cadmium Values"then"COPY"
Maximum data .Maximum data
points=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 6/8/2021 < 1 0.5 Std Dev. 0.0000 1 9/25/2018 < 1 0.5 Std Dev. 0.1239
2 6/4/2019 < 1 0.5 Mean 0.5000 2 12/5/2018 < 1 0.5 Mean 0.3421
3 6/1/2020 < 1 0.5 C.V. (default) 0.6000 3 3/12/2019 < 1 0.5 C.V. 0.3622
4 n 3 4 6/11/2019 < 1 0.5 n 19
5 5 9/11/2019 < 1 0.5
6 Mult Factor= 3.00 6 12/10/2019 < 1 0.5 Mult Factor= 1.23
7 Max. Value 0.50 ug/L 7 3/10/2020 < 1 0.5 Max. Value 0.500 ug/L
8 Max. Pred Cw 1.50 ug/L 8 6/9/2020 < 0.5 0.25 Max. Pred Cw 0.615 ug/L
9 9 9/8/2020 < 0.5 0.25
10 10 12/1/2020 < 0.5 0.25
11 11 3/2/2021 < 0.5 0.25
12 12 6/8/2021 < 0.5 0.25
13 13 6/9/2021 < 0.5 0.25
14 14 9/14/2021 < 0.5 0.25
15 15 12/8/2021 < 0.5 0.25
16 16 3/1/2022 < 0.5 0.25
17 17 6/8/2022 < 0.5 0.25
18 18 9/20/2022 < 0.5 0.25
19 19 12/13/2022 < 0.5 0.25
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
21873 RPA, data
-3- 5/3/2023

REASONABLE POTENTIAL ANALYSIS
Par05 Use"PASTE Par07 Use"PASTE
SPECIAL-Values" SPECIAL-Values"
Chlorides then"COPY". Total Phenolic Compounds then"COPY".
Maximum data Maximum data
Date Data BDL=1/2DL Results points=58 Date Data BDL=1/2DL Results points=58
1 6/8/2021 36 36 Std Dev. N/A 1 6/8/2021 < 10 5 Std Dev. 1.4434
2 Mean 36.0 2 6/4/2019 < 5 2.5 Mean 4.1667
3 C.V. (default) 0.6000 3 6/1/2020 < 10 5 C.V. (default) 0.6000
4 n 1 4 n 3
5 5
6 Mult Factor= 6.2 6 Mult Factor= 3.00
7 Max. Value 36.0 mg/L 7 Max. Value 5.0 ug/L
8 Max. Pred Cw 223.2 mg/L 8 Max. Pred Cw 15.0 ug/L
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
58 58
21873 RPA, data
-4- 5/3/2023

REASONABLE POTENTIAL ANALYSIS
Par10 Pal
Use"PASTE SPECIAL Use"PASTE SPECIAL
Chromium, Total Values"then"COPY" Copper Values"then"COPY"
Maximum data .Maximum data
points=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 9/25/2018 < 5 2.5 Std Dev. 0.0000 1 9/25/2018 3 3 Std Dev. 5.7987
2 12/5/2018 < 5 2.5 Mean 2.5000 2 12/5/2018 18 18 Mean 10.3000
3 3/12/2019 < 5 2.5 C.V. 0.0000 3 3/12/2019 11 11 C.V. 0.5630
4 6/11/2019 < 5 2.5 n 19 4 6/11/2019 20 20 n 25
5 9/11/2019 < 5 2.5 5 9/11/2019 29 29
6 12/10/2019 < 5 2.5 Mult Factor= 1.00 6 12/10/2019 11 11 Mult Factor= 1.26
7 3/10/2020 < 5 2.5 Max. Value 2.5 pg/L 7 3/10/2020 5 5 Max. Value 29.00 ug/L
8 6/9/2020 < 5 2.5 Max. Pred Cw 2.5 pg/L 8 6/9/2020 8 8 Max. Pred Cw 36.54 ug/L
9 9/8/2020 < 5 2.5 9 9/8/2020 7 7
10 12/1/2020 < 5 2.5 10 11/3/2020 6 6
11 3/2/2021 < 5 2.5 11 11/11/2020 12 12
12 6/8/2021 < 5 2.5 12 12/1/2020 12.5 12.5
13 6/9/2021 < 5 2.5 13 12/9/2020 7 7
14 9/14/2021 < 5 2.5 14 1/5/2021 5 5
15 12/8/2021 < 5 2.5 15 2/2/2021 11 11
16 3/1/2022 < 5 2.5 16 2/3/2021 10 10
17 6/8/2022 < 5 2.5 17 3/2/2021 7 7
18 9/20/2022 < 5 2.5 18 6/8/2021 11 11
19 12/13/2022 < 5 2.5 19 6/9/2021 9 9
20 20 9/14/2021 6 6
21 21 12/8/2021 8 8
22 22 3/1/2022 17 17
23 23 6/8/2022 4 4
24 24 9/20/2022 13 13
25 25 12/13/2022 7 7
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
21873 RPA, data
- 5- 5/3/2023

REASONABLE POTENTIAL ANALYSIS
Par12 Par14
Use"PASTE SPECIAL Use"PASTE SPECIAL
Cyanide Values"then"COPY" Lead Values"then"COPY"
Maximum data .Maximum data
points=58 points=58
Date Data BDL=1/2DL Results Date BDL=1/2DL Results
1 9/25/2018 < 5 5 Std Dev. 0.0000 1 9/25/2018 < 5 2.5 Std Dev. 0.6910
2 12/5/2018 < 5 5 Mean 5.00 2 12/5/2018 < 5 2.5 Mean 1.4600
3 3/12/2019 < 5 5 C.V. 0.0000 3 3/12/2019 < 5 2.5 C.V. 0.4733
4 6/11/2019 < 5 5 n 19 4 6/11/2019 < 5 2.5 n 25
5 9/11/2019 < 5 5 5 9/11/2019 < 5 2.5
6 12/10/2019 < 5 5 Mult Factor= 1.00 6 12/10/2019 < 5 2.5 Mult Factor= 1.22
7 3/10/2020 < 5 5 Max. Value 5.0 ug/L 7 3/10/2020 < 5 2.5 Max. Value 2.500 ug/L
8 6/9/2020 < 5 5 Max. Pred Cw 5.0 ug/L 8 6/9/2020 < 2 1 Max. Pred Cw 3.050 ug/L
9 9/8/2020 < 5.0 5 9 9/8/2020 < 2 1
10 12/1/2020 < 5.0 5 10 11/3/2020 < 2 1
11 3/2/2021 < 5 5 11 11/11/2020 < 2 1
12 6/8/2021 < 5 5 12 12/1/2020 2 2
13 6/9/2021 < 5 5 13 12/9/2020 < 2 1
14 9/14/2021 < 5 5 14 1/5/2021 < 2 1
15 12/8/2021 < 5 5 15 2/2/2021 < 2 1
16 3/1/2022 < 5 5 16 2/3/2021 < 2 1
17 6/8/2022 < 5 5 17 3/2/2021 < 2 1
18 9/20/2022 < 5 5 18 6/8/2021 < 2 1
19 12/13/2022 < 5 5 19 6/9/2021 < 2 1
20 20 9/14/2021 < 2 1
21 21 12/8/2021 < 2 1
22 22 3/1/2022 < 2 1
23 23 6/8/2022 < 2 1
24 24 9/20/2022 < 2 1
25 25 12/13/2022 < 2 1
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
21873 RPA, data
-6- 5/3/2023

REASONABLE POTENTIAL ANALYSIS
Par16 Par17 & Par18 use"PASTE
Use"PASTE SPECIAL SPECIAL-
Values"then"COPY" Values"then
Molybdenum .Maximum data Nickel "Copy.,.
points=58 Maximum data
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results points=58
1 9/25/2018 < 10 5 Std Dev. 7.7358 1 9/25/2018 < 10 5 Std Dev. 0.4588
2 12/5/2018 38 38 Mean 7.2105 2 12/5/2018 < 10 5 Mean 4.8947
3 3/12/2019 < 10 5 C.V. 1.0728 3 3/12/2019 < 10 5 C.V. 0.0937
4 6/11/2019 < 10 5 n 19 4 6/11/2019 < 10 5 n 19
5 9/11/2019 < 10 5 5 9/11/2019 < 10 5
6 12/10/2019 < 10 5 Mult Factor= 1.68 6 12/10/2019 < 10 5 Mult Factor= 1.06
7 3/10/2020 < 10 5 Max. Value 38.0 ug/L 7 3/10/2020 < 10 5 Max. Value 5.0 pg/L
8 6/9/2020 < 10 5 Max. Pred Cw 63.8 ug/L 8 6/9/2020 < 10 5 Max. Pred Cw 5.3 pg/L
9 9/8/2020 < 10 5 9 9/8/2020 < 10 5
10 12/1/2020 < 10 5 10 12/1/2020 < 10 5
11 3/2/2021 < 10 5 11 3/2/2021 < 10 5
12 6/8/2021 < 10 5 12 6/8/2021 3 3
13 6/9/2021 < 10 5 13 6/9/2021 < 10 5
14 9/14/2021 < 10 5 14 9/14/2021 < 10 5
15 12/8/2021 < 10 5 15 12/8/2021 < 10 5
16 3/1/2022 < 10 5 16 3/1/2022 < 10 5
17 6/8/2022 < 10 5 17 6/8/2022 < 10 5
18 9/20/2022 14 14 18 9/20/2022 < 10 5
19 12/13/2022 < 10 5 19 12/13/2022 < 10 5
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
21873 RPA, data
-7- 5/3/2023

REASONABLE POTENTIAL ANALYSIS
Par19 Par20
Use"PASTE SPECIAL- Use"PASTE SPECIAL
Values"then"COPY". Values"then"COPY"
Selenium Maximum data points Silver .Maximum data
=58 points=58
Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1 9/25/2018 < 10 5 Std Dev. 2.2302 1 9/25/2018 < 1 0.5 Std Dev. 0.1875
2 12/5/2018 < 10 5 Mean 2.1579 2 12/5/2018 < 1 0.5 Mean 0.2750
3 3/12/2019 < 10 5 C.V. 1.0335 3 3/12/2019 < 1 0.5 C.V. 0.6818
4 6/11/2019 < 10 5 n 19 4 6/11/2019 < 1 0.5 n 25
5 9/11/2019 < 10 5 5 9/11/2019 < 1 0.5
6 12/10/2019 < 10 5 Mult Factor= 1.65 6 12/10/2019 < 1 0.5 Mult Factor= 1.31
7 3/10/2020 < 10 5 Max. Value 5.0 ug/L 7 3/10/2020 < 1 0.5 Max. Value 0.500 ug/L
8 6/9/2020 < 1 0.5 Max. Pred Cw 8.3 ug/L 8 6/9/2020 < 1 0.5 Max. Pred Cw 0.655 ug/L
9 9/8/2020 < 1 0.5 9 9/8/2020 < 1 0.5
10 12/1/2020 < 1 0.5 10 11/3/2020 < 0.25 0.125
11 3/2/2021 < 1 0.5 11 11/11/2020 < 0.25 0.125
12 6/8/2021 < 1 0.5 12 12/1/2020 < 0.25 0.125
13 6/9/2021 < 1 0.5 13 12/9/2020 < 0.25 0.125
14 9/14/2021 < 1 0.5 14 1/5/2021 < 0.25 0.125
15 12/8/2021 < 1 0.5 15 2/2/2021 < 0.25 0.125
16 3/1/2022 < 1 0.5 16 2/3/2021 < 0.25 0.125
17 6/8/2022 < 1 0.5 17 3/2/2021 < 1 0.5
18 9/20/2022 < 1 0.5 18 6/8/2021 < 0.25 0.125
19 12/13/2022 < 1 0.5 19 6/9/2021 < 0.25 0.125
20 20 9/14/2021 < 0.25 0.125
21 21 12/8/2021 < 0.25 0.125
22 22 3/1/2022 < 0.25 0.125
23 23 6/8/2022 < 0.25 0.125
24 24 9/20/2022 < 0.25 0.125
25 25 12/13/2022 < 0.25 0.125
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
21873 RPA, data
-8- 5/3/2023

REASONABLE POTENTIAL ANALYSIS
Par21
Use"PASTE SPECIAL
Zinc Values"then"COPY"
Maximum data
points=58
Date Data BDL=1/2DL Results
1 9/25/2018 32 32 Std Dev. 23.9016
2 12/5/2018 54 54 Mean 47.2105
3 3/12/2019 38 38 C.V. 0.5063
4 6/11/2019 39 39 n 19
5 9/11/2019 61 61
6 12/10/2019 39 39 Mult Factor= 1.33
7 3/10/2020 46 46 Max. Value 114.0 ug/L
8 6/9/2020 114 114 Max. Pred Cw 151.6 ug/L
9 9/8/2020 41 41
10 12/1/2020 41 41
11 3/2/2021 25 25
12 6/8/2021 23 23
13 6/9/2021 16 16
14 9/14/2021 33 33
15 12/8/2021 77 77
16 3/1/2022 36 36
17 6/8/2022 51 51
18 9/20/2022 89 89
19 12/13/2022 42 42
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
21873 RPA, data
-9- 5/3/2023

Mayodan WWTP > Outfall 001
NCO021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 2.5 MGD
MAXIMUM DATA POINTS = 58
Qw (MGD) = 2.5000 WWTP/WTP Class: III COMBINED HARDNESS (mg/L)
1Q10S (cfs) = 61.34 IWC% @ 1Q10S = 5.941884536 Acute = 25 mg/L
7Q10S (cfs) = 75.00 IWC% @ 7Q10S = 4.912836767 Chronic =25 mg/L
7Q10W (cfs) = 131.00 IWC% @ 7Q10W= 2.873030584 YOU HAVE DESIGNATED THIS RECEIVING
30Q2 (cfs) = 150.00 IWC% @ 30Q2 = 2.518277823 STREAM AS WATER SUPPLY
Avg. Stream Flow, QA(cfs) = 362.00 IW%C @ QA= 1.059104886 Effluent Hard: 0 value > 100 mg/L
Receiving Stream: Mayo River HUC 03010103 Stream Class: C Effluent Hard Avg =45.9 mg/L
PARAMETER NC STANDARDS OR EPA CRITERIA J REASONABLE POTENTIAL RESULTS RECOMMENDED ACTION
TYPEAplied
Chronic Standard Acute n #Det. Max Pred Cw Allowable Cw
Acute (FW): 5,722.1
Arsenic C 150 FW(7Q10s) 340 ug/L
19 0 3.3 Chronic (FW): 3,053.2
Max MDL_= 5
Arsenic C 10 HH/WS(Qavg) ug/L NO DETECTS Chronic (HH): 944.2 No RP, Predicted Max< 50% of Allowable Cw- No
Max MDL 5 Monitoring required
Acute: 1,093.93
Beryllium NC 6.5 FW(7Q10s) 65 ug/L 3 0 1.50
Note: n<9 C.V. (default) Chronic: 132.31 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 1 Monitoring required
Acute: 54.522
Cadmium NC 0.5899 FW(701 Os) 3.2396 u�A 19 0 0.615
Chronic: 12.007 No RP, Predicted Max< 50% of Allowable Cw- No
NO DETECTS Max MDL= 1 Monitoring required
Acute: NO WQS
Chlorides NC 250 WS(701 Os) ma/L 1 1 223.2 __ _ _ _ _ _
Note: n< 9 C.V. (default) Chronic: 5,088.7 No RP, Predicted Max< 50% of Allowable Cw- No
Limited 1 >Allowable Cw Monitoring required
Acute: NO WQS
Total Phenolic Compounds NC 300 A(30Q2) ug/L 3 0 15.0 _ _ _______ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Note: n<9 C.V. (default) Chronic: 11,912.9 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 10 Monitoring required
Acute: 15,232.2
Chromium III NC ####### FW(7QlOs) 905.0818 µg/L 0 0 N/A
Chronic:-----2 396.4 - ----------------------------
Acute: 269.3
Chromium VI NC 11 FW(7QlOs) 16 µg/L 0 0 N/A
Chronic:----- 223.9-- ----------------------------
a: No monitoring required if all Total Chromium
Chromium, Total NC µg/L 19 0 2.5 Max reported value = 2.5 samples are < 5 pg/L or Pred. max for Total Cr is <
NO DETECTS Max MDL- 5 allowable Cw for Cr VI.
Acute: 176.24
Copper NC 7.8806 FW(7Q10s) 10.4720 ug/L 25 25 36.54
Chronic:----- 160.41-- ----------------------------
RP shown - apply Monthly Monitoring with Limit
No value >Allowable Cw
Acute: 370.3
Cyanide NC 5 FW(7010s) 22 10 u2/L 19 0 5.0 __ _ _______ _ _ _ -re
_ _ _ -5
_ _ _ _ _ _ _
Chronic: 101.8 No RP, Predicted Max< 50% of Allowable Cw- No
NO DETECTS Max MDL= 10 Monitoring required
21873 RPA, rpa
Page 1 of 2 5/3/2023

Mayodan WWTP > Outfall 001
NCO021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 2.5 MGD
Acute: 1,270.424
Lead NC 2.9416 FW(7Q10s) 75.4871 ug/L 25 1 3.050
Chronic: 59.876 No RP, Predicted Max< 50% of Allowable Cw- No
No value >Allowable Cw Monitoring required
Acute (FW): 5,641.5
Nickel NC 37.2313 FW(7Q10s) 335.2087 µg/L
19 1 5.3 Chronic (FW): --- 757.8 -- ----------------------------
No value->Allowable Cw __ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Nickel NC 25.0000 WS(7Q10s) µg/L Chronic (WS): 508.9 No RP, Predicted Max< 50% of Allowable Cw- No
No value >Allowable Cw Monitoring required
Acute: 942.5
Selenium NC 5 FW(7Q10s) 56 ug/L 19 0 8.3 ................................................
Chronic: 101.8
No RP, Predicted Max< 50% of Allowable Cw- No
NO DETECTS Max MDL= 10 Monitoring required
Acute: 4.988
Silver NC 0.06 FW(7Q10s) 0.2964 ug/L 25 0 0.655
Chronic: 1.221 All values non-detect < 1 ug/L and < 0.25 ug/L; No
monitoring required
NO DETECTS Max MDL= 1
Acute: 2,115.6 No RP, Predicted Max< 50% of Allowable Cw- No
Zinc NC ####### FW(7Q10s) 125.7052 ug/L 19 19 151.6 Monitoring required
Chronic:
-----2,579.E - ----------------------------
No value >Allowable Cw
Acute: NO WQS
Nitrate NC 10 WS(7Q10s) mg/L 45 44 17.07200
Chronic: 203.548 No RP, Predicted Max< 50% of Allowable Cw- No
No value >Allowable Cw Monitoring required
21873 RPA, rpa
Page 2 of 2 5/3/2023

Mayodan WWTP > Outfall 001
NCO021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 4.5 MGD
MAXIMUM DATA POINTS = 58
Qw (MGD) = 4.5000 WWTP/WTP Class: III COMBINED HARDNESS (mg/L)
1Q10S (cfs) = 61.34 IWC% @ 1Q10S = 10.21005636 Acute = 25 mg/L
7Q10S (cfs) = 75.00 IWC% @ 7Q10S = 8.508691674 Chronic =25 mg/L
7Q10W (cfs) = 131.00 IWC% @ 7Q10W= 5.055263635 YOU HAVE DESIGNATED THIS RECEIVING
30Q2 (cfs) = 150.00 IWC% @ 30Q2 = 4.443382704 STREAM AS WATER SUPPLY
Avg. Stream Flow, QA(cfs) = 362.00 IW%C @ QA= 1.890371976 Effluent Hard: 0 value > 100 mg/L
Receiving Stream: Mayo River HUC 03010103 Stream Class: C Effluent Hard Avg =45.9 mg/L
PARAMETER NC STANDARDS OR EPA CRITERIA J REASONABLE POTENTIAL RESULTS RECOMMENDED ACTION
TYPEAplied
Chronic Standard Acute n #Det. Max Pred Cw Allowable Cw
Acute (FW): 3,330.1
Arsenic C 150 FW(7Q10s) 340 ug/L
19 0 3.3 Chronic (FW): 1,762.9
Max MDL_= 5
Arsenic C 10 HH/WS(Qavg) ug/L NO DETECTS Chronic (HH): 529.0 No RP, Predicted Max< 50% of Allowable Cw- No
Max MDL 5 Monitoring required
Acute: 636.63
Beryllium NC 6.5 FW(7Q10s) 65 ug/L 3 0 1.50
Note: n<9 C.V. (default) Chronic: 76.39 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 1 Monitoring required
Acute: 31.730
Cadmium NC 0.5899 FW(7010s) 3.2396 u�A 19 0 0.615
Chronic: 6.933 No RP, Predicted Max< 50% of Allowable Cw- No
NO DETECTS Max MDL= 1 Monitoring required
Acute: NO WQS
Chlorides NC 250 WS(7010s) ma/L 1 1 223.2 __ _ _ _ _ _
Note: n< 9 C.V. (default) Chronic: 2,938.2 No RP, Predicted Max< 50% of Allowable Cw- No
Limited 1 >Allowable Cw Monitoring required
Acute: NO WQS
Total Phenolic Compounds NC 300 A(30Q2) ug/L 3 0 15.0 _ _ _______ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Note: n<9 C.V. (default) Chronic: 6,751.6 No RP, Predicted Max< 50% of Allowable Cw- No
Limited data set NO DETECTS Max MDL= 10 Monitoring required
Acute: 8,864.6
Chromium III NC ####### FW(7Q10s) 905.0818 µg/L 0 0 N/A
Chronic:-----1383.7 - ----------------------------
Acute: 156.7
Chromium VI NC 11 FW(7Q10s) 16 µg/L 0 0 N/A
Chronic:----- 129.3 -- ----------------------------
a: No monitoring required if all Total Chromium
Chromium, Total NC µg/L 19 0 2.5 Max reported value = 2.5 samples are < 5 pg/L or Pred. max for Total Cr is <
NO DETECTS Max MDL- 5 allowable Cw for Cr VI.
Acute: 102.57
Copper NC 7.8806 FW(7Q10s) 10.4720 ug/L 25 25 36.54
Chronic:----- 92.62-- ----------------------------
RP shown - apply Monthly Monitoring with Limit
No value >Allowable Cw
Acute: 215.5
Cyanide NC 5 FW(7010s) 22 10 u2/L 19 0 5.0 __ _ _______ ____ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Chronic: 58.8 No RP, Predicted Max< 50% of Allowable Cw- No
NO DETECTS Max MDL= 10 Monitoring required
21873 RPA, rpa
Page 1 of 2 5/3/2023

Mayodan WWTP > Outfall 001
NCO021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 4.5 MGD
Acute: 739.341
Lead NC 2.9416 FW(7Q10s) 75.4871 ug/L 25 1 3.050
Chronic: 34.572 No RP, Predicted Max< 50% of Allowable Cw- No
No value >Allowable Cw Monitoring required
Acute (FW): 3,283.1
Nickel NC 37.2313 FW(7Q10s) 335.2087 µg/L
19 1 5.3 Chronic (FW): --- 437.6-- ----------------------------
No value->Allowable Cw __ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Nickel NC 25.0000 WS(7Q10s) µg/L Chronic (WS): 293.8 No RP, Predicted Max< 50% of Allowable Cw- No
No value >Allowable Cw Monitoring required
Acute: 548.5
Selenium NC 5 FW(7Q10s) 56 ug/L 19 0 8.3 ................................................
Chronic: 58.8
No RP, Predicted Max< 50% of Allowable Cw- No
NO DETECTS Max MDL= 10 Monitoring required
Acute: 2.903
Silver NC 0.06 FW(7Q10s) 0.2964 ug/L 25 0 0.655
Chronic: 0.705 All values non-detect < 1 ug/L and < 0.25 ug/L; No
monitoring required
NO DETECTS Max MDL= 1
Acute: 1,231.2 No RP, Predicted Max< 50% of Allowable Cw- No
Zinc NC ####### FW(7Q10s) 125.7052 ug/L 19 19 151.6 Monitoring required
Chronic:-—-—-1,489.5 - ----------------------------
No value >Allowable Cw
Acute: NO WQS
Nitrate NC 10 WS(7Q10s) mg/L 45 44 17.07200
Chronic: 117.527 No RP, Predicted Max< 50% of Allowable Cw- No
No value >Allowable Cw Monitoring required
21873 RPA, rpa
Page 2 of 2 5/3/2023

Permit No. NCO021873
NPDES Implementation of Instream Dissolved Metals Standards-Freshwater Standards
The NC 2007-2015 Water Quality Standard(WQS)Triennial Review was approved by the NC
Environmental Management Commission(EMC)on November 13,2014. The US EPA subsequently
approved the WQS revisions on April 6,2016,with some exceptions. Therefore,metal limits in draft
permits out to public notice after April 6,2016 must be calculated to protect the new standards - as
approved.
Table 1.NC Dissolved Metals Water Q ality Standards/A uatic Life Protection
Parameter Acute FW, µg/l Chronic FW, µg/l Acute SW, µg/1 Chronic SW, µg/1
(Dissolved) (Dissolved) (Dissolved) (Dissolved)
Arsenic 340 150 69 36
Beryllium 65 6.5 --- ---
Cadmium Calculation Calculation 40 8.8
Chromium III Calculation Calculation --- ---
Chromium VI 16 11 1100 50
Copper Calculation Calculation 4.8 3.1
Lead Calculation Calculation 210 8.1
Nickel Calculation Calculation 74 8.2
Silver Calculation 0.06 1.9 0.1
Zinc Calculation Calculation 90 81
Table 1 Notes:
1. FW=Freshwater, SW= Saltwater
2. Calculation=Hardness dependent standard
3. Only the aquatic life standards listed above are expressed in dissolved form. Aquatic life
standards for Mercury and selenium are still expressed as Total Recoverable Metals due to
bioaccumulative concerns (as are all human health standards for all metals). It is still necessary
to evaluate total recoverable aquatic life and human health standards listed in 15A NCAC
2B.0200(e.g., arsenic at 10 µg/1 for human health protection; cyanide at 5 µg/L and fluoride at
1.8 mg/L for aquatic life protection).
Table 2.Dissolved Freshwater Standards for Hardness-Dependent Metals
The Water Effects Ratio(WER)is equal to one unless determined otherwise under 15A
NCAC 02B .0211 Subparagraph(11)(d)
Metal NC Dissolved Standard, µg/I
Cadmium,Acute WER*{1.136672-[ln hardness](0.041838)} e^10.9151 [ln hardness]-3.1485}
Cadmium,Acute Trout waters WER*{1.136672-[ln hardness](0.041838)} e^{0.9151[In hardness]-3.62361
Cadmium,Chronic WER*{1.101672-[ln hardness](0.041838)} •e^{0.7998[ln hardness]-4.445 11
Chromium III,Acute WER*0.316 e^{0.8190[ln hardness]+3.7256}
Chromium III,Chronic WER*0.860 e^{0.8190[ln hardness]+0.6848}
Copper,Acute WER*0.960 e^{0.9422[ln hardness]-1.700}
Copper,Chronic WER*0.960 e^{0.8545[ln hardness]-1.702}
Lead,Acute WER*{1.46203-[ln hardness](0.145712)} • e^{1.273[ln hardness]-1.460}
Lead,Chronic WER*{1.46203-[ln hardness](0.145712)} •e^{1.273[ln hardness]-4.705)
Nickel,Acute WER*0.998 e^{0.8460[ln hardness]+2.255}
Nickel,Chronic WER*0.997 e^{0.8460[ln hardness]+0.0584}
Page 1 of 4

Permit No. NCO021873
Silver,Acute WER*0.85 •e^{1.72[ln hardness]-6.59}
Silver,Chronic Not applicable
Zinc,Acute WER*0.978 e^{0.8473[ln hardness]+0.884}
Zinc,Chronic WER*0.986 e^{0.8473[ln hardness]+0.884}
General Information on the Reasonable Potential Analysis (RPA)
The RPA process itself did not change as the result of the new metals standards. However, application of
the dissolved and hardness-dependent standards requires additional consideration in order to establish the
numeric standard for each metal of concern of each individual discharge.
The hardness-based standards require some knowledge of the effluent and instream(upstream)hardness
and so must be calculated case-by-case for each discharge.
Metals limits must be expressed as `total recoverable' metals in accordance with 40 CFR 122.45(c). The
discharge-specific standards must be converted to the equivalent total values for use in the RPA
calculations. We will generally rely on default translator values developed for each metal(more on that
below),but it is also possible to consider case-specific translators developed in accordance with
established methodology.
RPA Permitting Guidance/WOBELs for Hardness-Dependent Metals -Freshwater
The RPA is designed to predict the maximum likely effluent concentrations for each metal of concern,
based on recent effluent data, and calculate the allowable effluent concentrations,based on applicable
standards and the critical low-flow values for the receiving stream.
If the maximum predicted value is greater than the maximum allowed value(chronic or acute),the
discharge has reasonable potential to exceed the standard,which warrants a permit limit in most cases. If
monitoring for a particular pollutant indicates that the pollutant is not present(i.e. consistently below
detection level),then the Division may remove the monitoring requirement in the reissued permit.
1. To perform a RPA on the Freshwater hardness-dependent metals the Permit Writer compiles the
following information:
• Critical low flow of the receiving stream, 7Q10(the spreadsheet automatically calculates
the 1 Q 10 using the formula 1 Q 10=0.843 (s7Q 10, cfs)0.993
• Effluent hardness and upstream hardness, site-specific data is preferred
• Permitted flow
• Receiving stream classification
2. In order to establish the numeric standard for each hardness-dependent metal of concern and for
each individual discharge,the Permit Writer must first determine what effluent and instream
(upstream)hardness values to use in the equations.
The permit writer reviews DMR's,Effluent Pollutant Scans, and Toxicity Test results for any
hardness data and contacts the Permittee to see if any additional data is available for instream
hardness values,upstream of the discharge.
If no hardness data is available,the permit writer may choose to do an initial evaluation using a
default hardness of 25 mg/L(CaCO3 or(Ca+Mg)). Minimum and maximum limits on the
hardness value used for water quality calculations are 25 mg/L and 400 mg/L,respectively.
If the use of a default hardness value results in a hardness-dependent metal showing reasonable
potential,the permit writer contacts the Permittee and requests 5 site-specific effluent and
upstream hardness samples over a period of one week. The RPA is rerun using the new data.
Page 2 of 4

Permit No. NCO021873
The overall hardness value used in the water quality calculations is calculated as follows:
Combined Hardness(chronic)
_(Permitted Flow,cfs *Avg. Effluent Hardness,mg/L)+s7Q10, cfs *Avg. Upstream Hardness,mg/L)
(Permitted Flow,cfs+s7Q10,cfs)
The Combined Hardness for acute is the same but the calculation uses the IQ 10 flow.
3. The permit writer converts the numeric standard for each metal of concern to a total recoverable
metal,using the EPA Default Partition Coefficients(DPCs)or site-specific translators, if any
have been developed using federally approved methodology.
EPA default partition coefficients or the"Fraction Dissolved"converts the value for
dissolved metal at laboratory conditions to total recoverable metal at in-stream
ambient conditions. This factor is calculated using the linear partition coefficients
found in The Metals Translator: Guidance for Calculating a Total Recoverable
Permit Limit from a Dissolved Criterion (EPA 823-B-96-007, June 1996)and the
equation:
Cdiss - 1
Ctotal I + { [Kpo] [ss('+a)] [10-6] }
Where:
ss=in-stream suspended solids concentration [mg/1],minimum of 10 mg/L used,
and
Kpo and a=constants that express the equilibrium relationship between dissolved
and adsorbed forms of metals. A list of constants used for each hardness-dependent
metal can also be found in the RPA program under a sheet labeled DPCs.
4. The numeric standard for each metal of concern is divided by the default partition coefficient(or
site-specific translator)to obtain a Total Recoverable Metal at ambient conditions.
In some cases,where an EPA default partition coefficient translator does not exist(ie. silver),the
dissolved numeric standard for each metal of concern is divided by the EPA conversion factor to
obtain a Total Recoverable Metal at ambient conditions. This method presumes that the metal is
dissolved to the same extent as it was during EPA's criteria development for metals. For more
information on conversion factors see the June, 1996 EPA Translator Guidance Document.
5. The RPA spreadsheet uses a mass balance equation to determine the total allowable concentration
(permit limits)for each pollutant using the following equation:
Ca=(s7Q 10+Qw)(Cwgs)—(s7Q 10) (Cb)
Qw
Where: Ca=allowable effluent concentration(µg/L or mg/L)
Cwqs=NC Water Quality Standard or federal criteria(µg/L or mg/L)
Cb=background concentration: assume zero for all toxicants except NH3* (µg/L or mg/L)
Qw=permitted effluent flow(cfs,match s7Q 10)
s7Q 10=summer low flow used to protect aquatic life from chronic toxicity and human
health through the consumption of water, fish, and shellfish from noncarcinogens (cfs)
* Discussions are on-going with EPA on how best to address background concentrations
Flows other than s7Q 10 may be incorporated as applicable:
IQ 10=used in the equation to protect aquatic life from acute toxicity
Page 3 of 4

Permit No. NC0021873
QA=used in the equation to protect human health through the consumption of water,
fish, and shellfish from carcinogens
30Q2=used in the equation to protect aesthetic quality
6. The permit writer enters the most recent 2-3 years of effluent data for each pollutant of concern.
Data entered must have been taken within four and one-half years prior to the date of the permit
application(40 CFR 122.21). The RPA spreadsheet estimates the 95th percentile upper
concentration of each pollutant. The Predicted Max concentrations are compared to the Total
allowable concentrations to determine if a permit limit is necessary. If the predicted max exceeds
the acute or chronic Total allowable concentrations,the discharge is considered to show
reasonable potential to violate the water quality standard, and a permit limit(Total allowable
concentration)is included in the permit in accordance with the U.S. EPA Technical Support
Document for Water Quality-Based Toxics Control published in 1991.
7. When appropriate,permit writers develop facility specific compliance schedules in accordance
with the EPA Headquarters Memo dated May 10,2007 from James Hanlon to Alexis Strauss on
40 CFR 122.47 Compliance Schedule Requirements.
8. The Total Chromium NC WQS was removed and replaced with trivalent chromium and
hexavalent chromium Water Quality Standards. As a cost savings measure,total chromium data
results may be used as a conservative surrogate in cases where there are no analytical results
based on chromium III or VI. In these cases,the projected maximum concentration(95th%) for
total chromium will be compared against water quality standards for chromium III and
chromium VI.
9. Effluent hardness sampling and instream hardness sampling,upstream of the discharge, are
inserted into all permits with facilities monitoring for hardness-dependent metals to ensure the
accuracy of the permit limits and to build a more robust hardness dataset.
10. Hardness and flow values used in the Reasonable Potential Analysis for this permit included:
Parameter Value Comments (Data Source)
Average Effluent Hardness(mg/L) 45.9 Default used; average from 912018
[Total as, CaCO3 or(Ca+Mg)] —1212022 DMRs
Average Upstream Hardness (mg/L) 25 Default used; average from review
[Total as, CaCO3 or(Ca+Mg)] period below 25 mg/L.
7Q 10 summer(cfs) 75 Historical file;previous fact sheet
1Q10(cfs) 96.21 Calculated in RPA
Permitted Flow(MGD) 2.5 with NPDES Files
expansions of
3.0 and 4.5
Date: 5/10/2023
Permit Writer: Nick Coco
Page 4 of 4

NH3/TRC WLA Calculations
Facility: Mayodan WWTP
PermitNo. NC0021873
Prepared By: Nick Coco
Enter Design Flow (MGD): 3
Enter s7Q10 (cfs): 75
Enter w7Q10 (cfs): 131
Total Residual Chlorine (TRC) Ammonia (Summer)
Daily Maximum Limit (ug/1) Monthly Average Limit(mg NH3-N/1)
s7Q10 (CFS) 75 s7Q10 (CFS) 75
DESIGN FLOW (MGD) 3 DESIGN FLOW (MGD) 3
DESIGN FLOW (CFS) 4.65 DESIGN FLOW (CFS) 4.65
STREAM STD (UG/L) 17.0 STREAM STD (MG/L) 1.0
Upstream Bkgd (ug/1) 0 Upstream Bkgd (mg/1) 0.22
IWC (%) 5.84 IWC (%) 5.84
Allowable Conc. (ug/1) 291 Allowable Conc. (mg/1) 13.6
Cap at 28 uq/L.Consistent with current limit. Consistent with current limit.Maintain limit.
Maintain limit.
Ammonia (Winter)
Monthly Average Limit(mg NH3-N/1)
Fecal Coliform w7Q10 (CFS) 131
Monthly Average Limit: 200/100ml DESIGN FLOW (MGD) 3
(If DF >331; Monitor) DESIGN FLOW (CFS) 4.65
(If DF<331; Limit) STREAM STD (MG/L) 1.8
Dilution Factor(DF) 17.13 Upstream Bkgd (mg/1) 0.22
IWC (%) 3.43
Allowable Conc. (mg/1) 46.3
>35 mg/L,Monitor and Report.
Consistent with current requirement.Maintain Monitor and Report.
Total Residual Chlorine
1. Cap Daily Max limit at 28 ug/l to protect for acute toxicity
Ammonia (as NH3-N)
1. If Allowable Conc > 35 mg/l, Monitor Only
2. Monthly Avg limit x 3 = Weekly Avg limit (Municipals)
3. Monthly Avg limit x 5 = Daily Max limit(Non-Munis)
If the allowable ammonia concentration is > 35 mg/L, no limit shall be imposed
Fecal Coliform
1. Monthly Avg limit x 2 =400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non-Muni)

NH3/TRC WLA Calculations
Facility: Mayodan WWTP
PermitNo. NC0021873
Prepared By: Nick Coco
Enter Design Flow (MGD): 4.5
Enter s7Q10 (cfs): 75
Enter w7Q10 (cfs): 131
Total Residual Chlorine (TRC) Ammonia (Summer)
Daily Maximum Limit (ug/1) Monthly Average Limit(mg NH3-N/1)
s7Q10 (CFS) 75 s7Q10 (CFS) 75
DESIGN FLOW (MGD) 4.5 DESIGN FLOW (MGD) 4.5
DESIGN FLOW (CFS) 6.975 DESIGN FLOW (CFS) 6.975
STREAM STD (UG/L) 17.0 STREAM STD (MG/L) 1.0
Upstream Bkgd (ug/1) 0 Upstream Bkgd (mg/1) 0.22
IWC (%) 8.51 IWC (%) 8.51
Allowable Conc. (ug/1) 200 Allowable Conc. (mg/1) 9.4
Cap at 28 uq/L.Consistent with current limit. Consistent with current limit.Maintain limit.
Maintain limit.
Ammonia (Winter)
Monthly Average Limit(mg NH3-N/1)
Fecal Coliform w7Q10 (CFS) 131
Monthly Average Limit: 200/100ml DESIGN FLOW (MGD) 4.5
(If DF >331; Monitor) DESIGN FLOW (CFS) 6.975
(If DF<331; Limit) STREAM STD (MG/L) 1.8
Dilution Factor(DF) 11.75 Upstream Bkgd (mg/1) 0.22
IWC (%) 5.06
Allowable Conc. (mg/1) 31.5
Consistent with current limit.Maintain limit.
Total Residual Chlorine
1. Cap Daily Max limit at 28 ug/l to protect for acute toxicity
Ammonia (as NH3-N)
1. If Allowable Conc > 35 mg/l, Monitor Only
2. Monthly Avg limit x 3 = Weekly Avg limit (Municipals)
3. Monthly Avg limit x 5 = Daily Max limit(Non-Munis)
If the allowable ammonia concentration is > 35 mg/L, no limit shall be imposed
Fecal Coliform
1. Monthly Avg limit x 2 =400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non-Muni)

NH3/TRC WLA Calculations
Facility: Mayodan WWTP
PermitNo. NC0021873
Prepared By: Nick Coco
Enter Design Flow (MGD): 2.5
Enter s7Q10 (cfs): 75
Enter w7Q10 (cfs): 131
Total Residual Chlorine (TRC) Ammonia (Summer)
Daily Maximum Limit (ug/1) Monthly Average Limit(mg NH3-N/1)
s7Q10 (CFS) 75 s7Q10 (CFS) 75
DESIGN FLOW (MGD) 2.5 DESIGN FLOW (MGD) 2.5
DESIGN FLOW (CFS) 3.875 DESIGN FLOW (CFS) 3.875
STREAM STD (UG/L) 17.0 STREAM STD (MG/L) 1.0
Upstream Bkgd (ug/1) 0 Upstream Bkgd (mg/1) 0.22
IWC (%) 4.91 IWC (%) 4.91
Allowable Conc. (ug/1) 346 Allowable Conc. (mg/1) 16.1
Cap at 28 uq/L.Consistent with current limit. Consistent with current limit.Maintain limit.
Maintain limit.
Ammonia (Winter)
Monthly Average Limit(mg NH3-N/1)
Fecal Coliform w7Q10 (CFS) 131
Monthly Average Limit: 200/100ml DESIGN FLOW (MGD) 2.5
(If DF >331; Monitor) DESIGN FLOW (CFS) 3.875
(If DF<331; Limit) STREAM STD (MG/L) 1.8
Dilution Factor(DF) 20.35 Upstream Bkgd (mg/1) 0.22
IWC (%) 2.87
Allowable Conc. (mg/1) 55.2
>35 mg/L,Monitor and Report.
Consistent with current requirement.Maintain Monitor and Report.
Total Residual Chlorine
1. Cap Daily Max limit at 28 ug/l to protect for acute toxicity
Ammonia (as NH3-N)
1. If Allowable Conc > 35 mg/l, Monitor Only
2. Monthly Avg limit x 3 = Weekly Avg limit (Municipals)
3. Monthly Avg limit x 5 = Daily Max limit(Non-Munis)
If the allowable ammonia concentration is > 35 mg/L, no limit shall be imposed
Fecal Coliform
1. Monthly Avg limit x 2 =400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non-Muni)

NCO021873 Mayodan WWTP 5/3/2023
BOD monthly removal rate TSS monthly removal rate
Month RR(%) Month RR (%) Month RR(%) Month RR(%)
August-18 93.03 February-21 81.51 August-18 91.49 February-21 77.26
September-18 86.33 March-21 96.12 September-18 86.90 March-21 92.17
October-18 91.28 April-21 96.39 October-18 85.04 April-21 95.64
November-18 83.44 May-21 89.75 November-18 83.20 May-21 91.42
December-18 83.60 June-21 88.30 December-18 73.53 June-21 85.60
January-19 91.51 July-21 91.77 January-19 85.16 July-21 88.29
February-19 79.49 August-21 87.70 February-19 82.77 August-21 81.76
March-19 92.35 September-21 93.00 March-19 87.61 September-21 91.04
April-19 93.21 October-21 97.77 April-19 92.12 October-21 94.28
May-19 95.83 November-21 98.79 May-19 97.37 November-21 98.08
June-19 90.53 December-21 98.41 June-19 90.67 December-21 97.56
July-19 96.48 January-22 94.52 July-19 95.49 January-22 93.62
August-19 95.59 February-22 84.61 August-19 92.50 February-22 68.00
September-19 97.30 March-22 93.32 September-19 93.17 March-22 93.24
October-19 96.76 April-22 94.30 October-19 91.09 April-22 93.53
November-19 93.45 May-22 71.30 November-19 90.00 May-22 60.65
December-19 91.95 June-22 94.90 December-19 86.34 June-22 95.82
January-20 88.43 July-22 96.37 January-20 80.82 July-22 96.46
February-20 82.24 August-22 91.40 February-20 83.35 August-22 92.75
March-20 91.23 September-22 92.82 March-20 88.20 September-22 91.26
April-20 87.10 October-22 97.13 April-20 75.23 October-22 94.97
May-20 80.03 November-22 97.34 May-20 60.34 November-22 96.75
June-20 84.74 December-22 96.33 June-20 84.86 December-22 90.34
July-20 96.08 January-23 July-20 91.74 January-23
August-20 91.77 February-23 August-20 85.63 February-23
September-20 95.84 March-23 September-20 92.78 March-23
October-20 95.41 April-23 October-20 91.52 April-23
November-20 97.06 May-23 November-20 93.88 May-23
December-20 88.25 June-23 December-20 75.10 June-23
January-21 82.91 July-23 January-21 75.88 July-23
Overall BOD removal rate 91.17 Overall TSS removal rate 87.63

Mayodan WWTP/NC0021873
Mercury Data Statistics (Method 1631E)
2018 2019 2020 2021 2022
#of Samples 2 4 5 8 9
Annual Average, ng/L 2.2 4.6 2.6 3.96 3.377778
Maximum Value, ng/L 2.80 8.40 8.00 11 12.4
TBEL, ng/L 47
WQBEL, ng/L 244.3

5/3/23 WQS= 12 ng/L MERCURY WQBEL/TBEL EVALUATION V:2013-6
Facility Name
Mayodan WWTP/NC0021873 No Limit Required
/Permit No.
MMP Required
Total Mercury 1631E PQL=0.5 ng/L 7Q10s = 75.000 cfs WQBEL= 244.26 ng/L
Date Modifier Data Entry Value Permitted Flow= 2.500 47 ng/L
9/25/18 1.6 1.6
12/5/18 2.8 2.8 2.2 ng/L-Annual Average for 2018
3/12/19 2.8 2.8
6/11/19 6.7 6.7
9/11/19 < 1 0.5
12/10/19 8.4 8.4 4.6 ng/L-Annual Average for 2019
3/10/20 2.8 2.8
6/9/20 1 1
9/1/20 < 1 0.5
9/8/20 < 1 0.5
12/2/20 8 8 2.6 ng/L-Annual Average for 2020
3/2/21 3.9 3.9
3/3/21 11 11
5/18/21 3.2 3.2
6/8/21 3.2 3.2
6/9/21 4 4
9/15/21 1.4 1.4
11/10/21 2.5 2.5
12/8/21 2.5 2.5 4.0 ng/L-Annual Average for 2021
3/1/22 5.2 5.2
5/3/22 12.4 12.4
6/14/22 < 1 0.5
6/29/22 < 1 0.5
8/3/22 1.7 1.7
9/13/22 1.7 1.7
10/12/22 2.9 2.9
11/9/22 4.1 4.1

12/13/22 1.4 1.4 3.4 ng/L-Annual Average for 2022

Mayodan WWTP/NC0021873
Mercury Data Statistics (Method 1631E)
2018 2019 2020 2021 2022
#of Samples 2 4 5 8 9
Annual Average, ng/L 2.2 4.6 2.6 3.96 3.377778
Maximum Value, ng/L 2.80 8.40 8.00 11 12.4
TBEL, ng/L 47
WQBEL, ng/L 141.0

5/3/23 WQS= 12 ng/L MERCURY WQBEL/TBEL EVALUATION V:2013-6
Facility Name
Mayodan WWTP/NC0021873 No Limit Required
/Permit No.
MMP Required
Total Mercury 1631E PQL=0.5 ng/L 7Q10s = 75.000 cfs WQBEL= 141.03 ng/L
Date Modifier Data Entry Value Permitted Flow= 4.500 47 ng/L
9/25/18 1.6 1.6
12/5/18 2.8 2.8 2.2 ng/L-Annual Average for 2018
3/12/19 2.8 2.8
6/11/19 6.7 6.7
9/11/19 < 1 0.5
12/10/19 8.4 8.4 4.6 ng/L-Annual Average for 2019
3/10/20 2.8 2.8
6/9/20 1 1
9/1/20 < 1 0.5
9/8/20 < 1 0.5
12/2/20 8 8 2.6 ng/L-Annual Average for 2020
3/2/21 3.9 3.9
3/3/21 11 11
5/18/21 3.2 3.2
6/8/21 3.2 3.2
6/9/21 4 4
9/15/21 1.4 1.4
11/10/21 2.5 2.5
12/8/21 2.5 2.5 4.0 ng/L-Annual Average for 2021
3/1/22 5.2 5.2
5/3/22 12.4 12.4
6/14/22 < 1 0.5
6/29/22 < 1 0.5
8/3/22 1.7 1.7
9/13/22 1.7 1.7
10/12/22 2.9 2.9
11/9/22 4.1 4.1

12/13/22 1.4 1.4 3.4 ng/L-Annual Average for 2022

Reduction in Frequency Evalaution
Facility: Mayodan WWTP
Permit No. NC0021873
Review period(use 3
12/2019-12/2022 Note:weighted ammonia average limits assume winter limits equivalent to summer limits
yrs)
Approval Criteria: Y/N?
1. Not currently under SOC Y
2. Not on EPA Quarterly noncompliance report Y
3.Facility or employees convicted of CWA N
violations
Weekly Monthly 500� 200% 200/ monthly #civil penalty 3-yr mean #daily #daily #of non-
p Reduce
Data Review Units average (geo mean <50%? samples <15? samples <20? >2? >1? Frequency?
average limit limit MA for FC) MA >200% WA >200% limit asessment (Yes/No)
violations
BOD(Weighted) mg/L 45 30 15 2 Y 60 0 Y 1 N 0 N Y
TSS mg/L 45 30 15 4.2676084 Y 60 3 Y 2 N 0 N Y
Ammonia(weighted) mg/L 35 16 1 8 1 1.0943803 1 Y 32 0 1 Y 0 N 0 N Y
Fecal Coliform #/100 400 1 200 1 1001 4.1139045 1 Y 1 800 1 37 N 1 1 N 1 0 1 N I N

MONITORING REPORT(MR)VIOLATIONS for: Report Date: 03/16/22 Page 1 of 16
Permit: NCO021873 MRS Betweei 3 - 2018 and 3 - 2023 Region: % Violation Category:Limit Violation Program Category:
Facility Name:% Param Nam(% County: % Subbasin:% Violation Action:%
Major Minor: %
PERMIT: NCO021873 FACILITY: Town of Mayodan-Mayodan WWTP COUNTY: Rockingham REGION: Winston-Salem
Limit Violation
MONITORING VIOLATION UNIT OF CALCULATED %
REPORT OUTFALL LOCATION PARAMETER DATE FREQUENCY MEASURE LIMIT VALUE Over VIOLATION TYPE VIOLATION ACTION
02-2022 001 Effluent BOD,5-Day(20 Deg.C)- 02/26/22 2 X week mg/I 45 49.65 10.3 Weekly Average Proceed to NOV
Concentration Exceeded
04-2018 001 Effluent Chlorine,Total Residual 04/05/18 3 X week ug/I 28 33 17.9 Daily Maximum No Action, BPJ
Exceeded
04-2018 001 Effluent Chlorine,Total Residual 04/06/18 3 X week ug/I 28 33 17.9 Daily Maximum No Action, BPJ
Exceeded
04-2018 001 Effluent Chlorine,Total Residual 04/23/18 3 X week ug/I 28 38 35.7 Daily Maximum No Action, BPJ
Exceeded
05-2018 001 Effluent Chlorine,Total Residual 05/02/18 3 X week ug/I 28 35 25 Daily Maximum No Action, BPJ
Exceeded
05-2018 001 Effluent Chlorine,Total Residual 05/07/18 3 X week ug/I 28 40 42.9 Daily Maximum No Action, BPJ
Exceeded
05-2018 001 Effluent Chlorine,Total Residual 05/09/18 3 X week ug/I 28 43 53.6 Daily Maximum No Action, BPJ
Exceeded
05-2018 001 Effluent Chlorine,Total Residual 05/14/18 3 X week ug/I 28 32 14.3 Daily Maximum No Action, BPJ
Exceeded
05-2018 001 Effluent Chlorine,Total Residual 05/25/18 3 X week ug/I 28 39 39.3 Daily Maximum No Action, BPJ
Exceeded
06-2018 001 Effluent Chlorine,Total Residual 06/27/18 3 X week ug/I 28 31 10.7 Daily Maximum No Action, BPJ
Exceeded
07-2018 001 Effluent Chlorine,Total Residual 07/04/18 3 X week ug/I 28 39 39.3 Daily Maximum No Action, BPJ
Exceeded
07-2018 001 Effluent Chlorine,Total Residual 07/11/18 3 Xweek ug/I 28 34 21.4 Daily Maximum No Action, BPJ
Exceeded
07-2018 001 Effluent Chlorine,Total Residual 07/16/18 3 X week ug/I 28 39 39.3 Daily Maximum No Action, BPJ
Exceeded
07-2018 001 Effluent Chlorine,Total Residual 07/27/18 3 X week ug/I 28 33 17.9 Daily Maximum No Action, BPJ
Exceeded
08-2018 001 Effluent Chlorine,Total Residual 08/02/18 3 X week ug/I 28 44 57.1 Daily Maximum No Action, BPJ
Exceeded
08-2018 001 Effluent Chlorine,Total Residual 08/15/18 3 X week ug/I 28 39 39.3 Daily Maximum No Action, BPJ
Exceeded

MONITORING REPORT(MR) VIOLATIONS for: Report Date: 03/16/22 Page 15 of 16
Permit: NCO021873 MRS Betweel 3 - 2018 and 3 - 2023 Region: % Violation Category:Limit Violation Program Category:
Facility Name:% Param Nam(% County: % Subbasin:% Violation Action:%
Major Minor: %
PERMIT: NCO021873 FACILITY: Town of Mayodan-Mayodan WWTP COUNTY: Rockingham REGION: Winston-Salem
Limit Violation
MONITORING VIOLATION UNIT OF CALCULATED %
REPORT OUTFALL LOCATION PARAMETER DATE FREQUENCY MEASURE LIMIT VALUE Over VIOLATION TYPE VIOLATION ACTION
08-2022 001 Effluent Chlorine,Total Residual 08/25/22 3 X week ug/I 28 33 17.9 Daily Maximum No Action, BPJ
Exceeded
09-2022 001 Effluent Chlorine,Total Residual 09/19/22 3 X week ug/I 28 39 39.3 Daily Maximum No Action, BPJ
Exceeded
09-2022 001 Effluent Chlorine,Total Residual 09/20/22 3 X week ug/I 28 45 60.7 Daily Maximum No Action, BPJ
Exceeded
09-2022 001 Effluent Chlorine,Total Residual 09/28/22 3 X week ug/I 28 31 10.7 Daily Maximum No Action, BPJ
Exceeded
11-2022 001 Effluent Chlorine,Total Residual 11/02/22 3 X week ug/I 28 35 25 Daily Maximum No Action, BPJ
Exceeded
11-2022 001 Effluent Chlorine,Total Residual 11/03/22 3 X week ug/I 28 33 17.9 Daily Maximum No Action, BPJ
Exceeded
11-2022 001 Effluent Chlorine,Total Residual 11/08/22 3 X week ug/I 28 29 3.6 Daily Maximum No Action, BPJ
Exceeded
11-2022 001 Effluent Chlorine,Total Residual 11/09/22 3 X week ug/I 28 35 25 Daily Maximum No Action, BPJ
Exceeded
11-2022 001 Effluent Chlorine,Total Residual 11/22/22 3 X week ug/I 28 41 46.4 Daily Maximum No Action, BPJ
Exceeded
11-2022 001 Effluent Chlorine,Total Residual 11/23/22 3 X week ug/I 28 49 75 Daily Maximum No Action, BPJ
Exceeded
12-2022 001 Effluent Chlorine,Total Residual 12/01/22 3 Xweek ug/I 28 41 46.4 Daily Maximum No Action, BPJ
Exceeded
01-2023 001 Effluent Chlorine,Total Residual 01/17/23 5 X week ug/I 28 50 78.6 Daily Maximum None
Exceeded
01-2023 001 Effluent Chlorine,Total Residual 01/20/23 5 X week ug/I 28 45 60.7 Daily Maximum No Action, BPJ
Exceeded
09-2018 001 Effluent Coliform, Fecal MF, MFC 09/15/18 3 X week #/100ml 400 457.62 14.4 Weekly Geometric Mean Proceed to NOD
Broth,44.5 C Exceeded
08-2021 001 Effluent Coliform, Fecal MF, MFC 08/21/21 3 X week #/100ml 400 644.84 61.2 Weekly Geometric Mean Proceed to NOV
Broth,44.5 C Exceeded
05-2020 001 Effluent Solids,Total Suspended- 05/23/20 2 X week mg/I 45 49.2 9.3 Weekly Average Proceed to NOD
Concentration Exceeded

MONITORING REPORT(MR)VIOLATIONS for: Report Date: 03/16/22 Page 16 of 16
Permit: NCO021873 MRS Betweel 3 - 2018 and 3 - 2023 Region: % Violation Category:Limit Violation Program Category:
Facility Name:% Param Nam(% County: % Subbasin:% Violation Action:%
Major Minor:
PERMIT: NCO021873 FACILITY: Town of Mayodan-Mayodan WWTP COUNTY: Rockingham REGION: Winston-Salem
Limit Violation
MONITORING VIOLATION UNIT OF CALCULATED %
REPORT OUTFALL LOCATION PARAMETER DATE FREQUENCY MEASURE LIMIT VALUE Over VIOLATION TYPE VIOLATION ACTION
02-2022 001 Effluent Solids,Total Suspended- 02/26/22 2 X week mg/I 45 135 200 Weekly Average Proceed to NOV
Concentration Exceeded
02-2022 001 Effluent Solids,Total Suspended- 02/28/22 2 X week mg/I 30 36.66 22.2 Monthly Average Proceed to NOV
Concentration Exceeded

Whole Effluent Toxicity Testing and Self Monitoring Summary
Marshall WWTP NCO021733/001 County: Madison Region: ARO Basin: FRB04 Feb May Aug Nov SOC JOC:
Fthd24PF Begin: 7/1/2022 24hr p/f ac lim:90% + NonComp: Single 70,10: 535 PF: 0.40 IWC: 0.12 Freq: Q
J F M A M J J A S O N D
2019 - Pass - - Pass - - Pass - - Pass -
2020 - Pass - - Pass - - Pass - - Pass -
2021 - Pass - - Pass>100(P) >100(P) >100(P) Pass>100(P) - - Pass -
2022 - Pass - - Pass - - Pass - - Pass -
2023 - Pass - - - - - - - - - -
Martin County WTP NCO089435/001 County: Martin Region: WARO Basin: ROA09 Mar Jun Sep Dec SOC JOC:
Ceri7dPF Begin: 4/1/2014 Chr Monit:90% NonComp: 7Q10: PF: IWC: Freq: Q
J F M A M J J A S O N D
2019 - - Pass - - Pass - - Pass - - Pass
2020 - - Pass - - Pass - - Pass - - Pass
2021 - - Pass - - Pass - - H - - H
2022 - - H - - H - - H - - H
Maxton WTP NCO048577/001 County: Robeson Region: FRO Basin: LUM51 Jan Apr Jul Oct SOC JOC:
Ceri7dPF Begin: 9/1/2014 Chr Monit:90% NonComp: 70.10: PF: IWC: Freq: Q
J F M A M J J A S O N D
2019 Fail - - Fail - - NR - - Pass - -
2020 Fail - - Pass - - Pass - - Pass - -
2021 Pass - - Pass - - Pass - - Pass - -
2022 Pass - - Fail - - Pass - - Fail - -
2023 Pass - - - - - - - - - - -
Mayodan WTP,Town of NCO046302/001 County: Rockingham Region: WSRO Basin: ROA02 Mar Jun Sep Dec SOC JOC:
Ceri48PF Begin: 1/1/2018 Acu Cerio 48hr PF M NonComp: 70.10: PF: IWC: Freq: Q
J F M A M J J A S O N D
2019 - - Pass - - Pass - - Pass - - Pass
2020 - - Pass - - Pass - - Pass - - Pass
2021 - - Pass - - Pass - - Pass - - Pass
2022 - - Pass - - Pass - - Pass - - Pass
Mayodan WWTP NCO021873/001 County: Rockingham Region: WSRO Basin: ROA02 Mar Jun Sep Dec SOC JOC:
Ceri7dPF Begin: 8/1/2018 chr lim: 2.5MGD @ 5 + NonComp: Single 70,10: 75 PF: 4.5 IWC: 8.5 Freq: Q
J F M A M J J A S O N D
2019 - - Pass - - Pass - - Pass - - Pass
2020 - - Pass - - Pass - - Pass - - Pass
2021 - - Pass>20(P) - - >20(P)Pass - - INVALID Pass >20(P) - >20(P)INVALID Pass
2022 - - Pass - - INVALID Pass - - Pass - - Pass
Leeend: P=Fathead minnow(PimDhales oromelas).H=No Flow(facility is active).s=SDlit test between Certified Labs Page 63 of 106

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 2 u 3 I NCO021873 111 121 22/08/04 I17 18 L D] 19 I G I 201 I
211IIIII 111111III II III III1 I I IIIII IIIIIIIII II r6
Inspection Work Days Facility Self-Monitoring Evaluation Rating B1 QA ----------------------Reserved-------------------
67 70LJ 71Ity 72 L-J 73 1 74 79 I I I I 80
Section B: Facility Data
Name and Location of Facility Inspected(For Industrial Users discharging to POTW,also include Entry Time/Date Permit Effective Date
POTW name and NPDES permit Number) 11:15AM 22/08/04 18/08/01
Mayodan WWTP
293 Caldwell Rd Exit Time/Date Permit Expiration Date
Mayodan NC 270272019 12:30PM 22/08/04 22/05/31
Name(s)of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s) Other Facility Data
Nadine Blackwell/Coordinatory Pretreatment//
Name,Address of Responsible Official/Title/Phone and Fax Number
Contacted
Debra E Cardwell,210 W Main St Mayodan NC 270272019/Town
Manager/336-427-0241/3364277592 No
Section C:Areas Evaluated During Inspection (Check only those areas evaluated)
Pretreatment
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
Alex Lowe DWR/WSRO WQ/336-776-9689/
Seren Homer DWR/WSRO WQ/336-776-9698/
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 (Cont.) 1
31 NCO021873 I11 12I 22/08/04 117 18 I D
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
On August 4, 2022, Alex Lowe and Seren Homer of the DWR WSRO conducted a routine
pretreatment compliance inspection of the Town of Mayodan pretreatment program. Pretreatment
Coordinator Nadine Blackwell assisted the inspection throuhout.
A review of the program elements indicated that no documents had expired, and all approval letters
were available for review. No copy of the original submission communications for the HWA and the
ERP were included, so Mr. Lowe requested that Ms. Blackwell include that additional documentation
moving forward.
File reviews of three SIUs were conducted: Ruger, Unifi, and Sans Technical. All three files were
well-maintained, and indicated full compliance with permit requirements (including POTW and SIU
sampling and ERP actions).
Ms. Blackwell noted that the new contact person at town hall is Kathleen Patterson, Town Manager.
BIMS was updated accordingly.
No indications of non-compliance were found, and as such this program is considered satisfactory.
Page# 2

Permit: NC0021873 Owner-Facility: Mayodan WWTP
Inspection Date: 08/04/2022 Inspection Type: Pretreatment Compliance
Yes No NA NE
Page# 3

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 NCO021873 I11 121 21/12/09 I17 18I� I 19 I G I 201 I
211IIIII 111111III II III III1 I I IIIII IIIIIIIII II r6
Inspection Work Days Facility Self-Monitoring Evaluation Rating B1 QA ----------------------Reserved-------------------
67 70L J 71 Ity 72 L-J 73 1 74 79 I I I I 80
Section B: Facility Data
Name and Location of Facility Inspected(For Industrial Users discharging to POTW,also include Entry Time/Date Permit Effective Date
POTW name and NPDES permit Number) 08:15AM 21/12/09 18/08/01
Mayodan WWTP
293 Caldwell Rd Exit Time/Date Permit Expiration Date
Mayodan NC 270272019 09:45AM 21/12/09 22/05/31
Name(s)of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s) Other Facility Data
Jamie C.Whitten/ORC/336-427-5733/
Name,Address of Responsible Official/Title/Phone and Fax Number
Contacted
Debra E Cardwell,210 W Main St Mayodan NC 270272019/Town
Manager/336-427-0241/3364277592 No
Section C:Areas Evaluated During Inspection (Check only those areas evaluated)
Permit 0 Flow Measurement Operations&Maintenar 0 Records/Reports
Self-Monitoring Progran 0 Facility Site Review Effluent/Receiving Wate
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
Jordan Burbage DWR/WSRO WQ/336-776-9697/
Michael M Mickey DWR/WSRO WQ/336-776-9697/
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 (Cont.) 1
31 NCO021873 I11 12I 21/12/09 117 18 i c i
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
Overall, facility is well-kept and demonstrates a solid track record of compliance. This is despite the
influent bypassing the barscreen, which is corroded and in a state of disrepair. DWR strongly
recommends making ends meet to find an adequate replacement in 2022. Until then, trash will
continue to enter the sedimentation basin, aeration basin, and digesters, suppressing treatment
efficacy and increasing wear and tear on pumps and aerators. This is evidenced by (1) the
08/17/2021 fecal exceedance due to excessive rainfall and (2)the surface aerator that is currently in
the shop. With the plant currently down to 3 out of 4 aerators, a significant dead zone exists in the far
corner of the aeration basin for the time being.
Lastly, the permit expires 05/31/2022 and the renewal application is past due as of 11/30/21. ORC
did mention beginning the renewal process.
Page# 2

Permit: NCO021873 Owner-Facility: Mayodan WWTP
Inspection Date: 12/09/2021 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: With the exception of the original basins that are no longer in use, facility is clean and
appears to maintain good housekeeping practices.
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? ■ ❑ ❑ ❑
#Are there any special conditions for the permit? ❑ 0 ❑ ❑
Is access to the plant site restricted to the general public? 0 ❑ ❑ ❑
Is the inspector granted access to all areas for inspection? ■ ❑ ❑ ❑
Comment: Permit expires end of May 2022 and renewal application was due end of November
2021.
Effluent Pipe Yes No NA NE
Is right of way to the outfall properly maintained? ❑ ❑ ❑ ■
Are the receiving water free of foam other than trace amounts and other debris? ❑ ❑ ❑
If effluent (diffuser pipes are required) are they operating properly? ❑ ❑ ❑
Comment: We did not visit the pipe this time but recommend taking the walk next inspection.
Bar Screens Yes No NA NE
Type of bar screen
a.Manual ❑
b.Mechanical
Are the bars adequately screening debris? ❑ 0 ❑ ❑
Is the screen free of excessive debris? ❑ ❑ ❑
Is disposal of screening in compliance? ❑ ❑ 0 ❑
Is the unit in good condition? ❑ 0 ❑ ❑
Comment: Original barscreen (1987) is corroded, in a state of disrepair, and has been bypassed
for quite some time. DWR strongly recommends a full replacement in 2022.
Equalization Basins Yes No NA NE
Is the basin aerated? ❑ 0 ❑ ❑
Page# 3

Permit: NCO021873 Owner-Facility: Mayodan WWTP
Inspection Date: 12/09/2021 Inspection Type: Compliance Evaluation
Equalization Basins Yes No NA NE
Is the basin free of bypass lines or structures to the natural environment? 0 ❑ ❑ ❑
Is the basin free of excessive grease? 0 ❑ ❑ ❑
Are all pumps present? ❑ 0 ❑ ❑
Are all pumps operable? ❑ ❑ 0 ❑
Are float controls operable? ❑ ❑ ❑
Are audible and visual alarms operable? ❑ ❑ ❑
# Is basin size/volume adequate? 0 ❑ ❑ ❑
Comment: EQ basin acting as overflow but my understanding is it is not currently part of treatment
process. Pumps have been pulled to use elsewhere.
Primary Clarifier Yes No NA NE
Is the clarifier free of black and odorous wastewater? 0 ❑ ❑ ❑
Is the site free of excessive buildup of solids in center well of circular clarifier? 0 ❑ ❑ ❑
Are weirs level? 0 ❑ ❑ ❑
Is the site free of weir blockage? ■ ❑ ❑ ❑
Is the site free of evidence of short-circuiting? 0 ❑ ❑ ❑
Is scum removal adequate? 0 ❑ ❑ ❑
Is the site free of excessive floating sludge? 0 ❑ ❑ ❑
Is the drive unit operational? 0 ❑ ❑ ❑
Is the sludge blanket level acceptable? 0 ❑ ❑ ❑
Is the sludge blanket level acceptable? (Approximately '/4 of the sidewall depth) ❑ ❑ ❑
Comment: Clarifiers look good.
Aeration Basins Yes No NA NE
Mode of operation Ext. Air
Type of aeration system Surface
Is the basin free of dead spots? ❑ 0 ❑ ❑
Are surface aerators and mixers operational? ■ ❑ ❑ ❑
Are the diffusers operational? 0 ❑ ❑ ❑
Is the foam the proper color for the treatment process? 0 ❑ ❑ ❑
Does the foam cover less than 25% of the basin's surface? ❑ 0 ❑ ❑
Is the DO level acceptable? 0 ❑ ❑ ❑
Is the DO level acceptable?(1.0 to 3.0 mg/1) 0 ❑ ❑ ❑
Page# 4

Permit: NC0021873 Owner-Facility: Mayodan WWTP
Inspection Date: 12/09/2021 Inspection Type: Compliance Evaluation
Aeration Basins Yes No NA NE
Comment: Having to bypass the barscreen, pumps are being worked harder which is effecting
their lifespan. 1 of the 4 aerators is currently in repair shop undergoing full rebuild.
Even so with 1/4 of the basin a "dead zone," the plant continues meeting permit limits.
Disinfection-Liquid Yes No NA NE
Is there adequate reserve supply of disinfectant? 0 ❑ ❑ ❑
(Sodium Hypochlorite) Is pump feed system operational? 0 ❑ ❑ ❑
Is bulk storage tank containment area adequate? (free of leaks/open drains) 0 ❑ ❑ ❑
Is the level of chlorine residual acceptable? 0 ❑ ❑ ❑
Is the contact chamber free of growth, or sludge buildup? 0 ❑ ❑ ❑
Is there chlorine residual prior to de-chlorination? ❑ ❑ ❑
Comment: Plant operates two contact chambers with ample contact time.
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? 0 ❑ ❑ ❑
Are the tablets the proper size and type? ❑ ❑ ❑
Comment: Effluent frequently measures high residual CI but seldom over the limit.
Are tablet de-chlorinators operational? ❑ ❑ ❑
Number of tubes in use?
Comment:
Standby Power Yes No NA NE
Is automatically activated standby power available? 0 ❑ ❑ ❑
Is the generator tested by interrupting primary power source? 0 ❑ ❑ ❑
Is the generator tested under load? ■ ❑ ❑ ❑
Was generator tested & operational during the inspection? ❑ 0 ❑ ❑
Do the generator(s) have adequate capacity to operate the entire wastewater site? 0 ❑ ❑ ❑
Is there an emergency agreement with a fuel vendor for extended run on back-up ❑ ❑ ❑ ■
power?
Is the generator fuel level monitored? 0 ❑ ❑ ❑
Comment: Facility maintains contract with Carolina CAT for quarterly maintenance and fuel.
Page# 5

Permit: NCO021873 Owner-Facility: Mayodan WWTP
Inspection Date: 12/09/2021 Inspection Type: Compliance Evaluation
Standby Power Yes No NA NE
Pumps-RAS-WAS Yes No NA NE
Are pumps in place? 0 ❑ ❑ ❑
Are pumps operational? 0 ❑ ❑ ❑
Are there adequate spare parts and supplies on site? ❑ ❑ ❑
Comment: Pumps are currently being taxed harder due to solids bypassing barscreen.
Influent Sampling Yes No NA NE
# Is composite sampling flow proportional? ❑ 0 ❑ ❑
Is sample collected above side streams? 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 0 ❑ ❑ ❑
degrees Celsius)?
Is sampling performed according to the permit? 0 ❑ ❑ ❑
Comment: Facility receives waste streams from Stoneville, Madison, and Mayodan. Unable to
collect influent flow proportionally.
Effluent Sampling Yes No NA NE
Is composite sampling flow proportional? 0 ❑ ❑ ❑
Is sample collected below all treatment units? 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 0 ❑ ❑ ❑
degrees Celsius)?
Is the facility sampling performed as required by the permit (frequency, sampling type ❑ ❑ ❑
representative)?
Comment: Effluent flow meter was calibrated January 2021
Upstream / Downstream Sampling Yes No NA NE
Is the facility sampling performed as required by the permit (frequency, sampling type, M ❑ ❑ ❑
and sampling location)?
Comment:
Page# 6

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ATTACHEMENT I
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan WWTP(NC0021873)
DMR Data (1/1/2020- 12/31/2022)
REDUCED MONITORING CRITERIA SUMMARY
1) Requirement:mean<50%of monthly average
BOD Avg of 8.6 is<15(50%of BOD Monthly Avg)
TSS Avg of 10.5 is<15(50%of TSS Monthly Avg)
Fecal Coliform Geomean Avg of 7 is<100(50%of Fecal Coliform Monthly Avg)
NH3-N Summer Avg of 2 2 is<8(50%of NH3-N Summer Monthly Avg)
2) No more than 15 daily samples can be>200%of the weekly average limit
BOD:1 Samples>200%of weekly avg limit
TSS:1 Samples>200%of weekly avg limit
NH3-N(Summer):0 Sample>200%of weekly avg limit.
3) No more than 20 daily samples can be>200%of the weekly average limit
Fecal Coliform:35 Samples>200%of weekly avg limit
4) Sampling results shall not show more than two non-monthly avg.limit violations in past year
0 non-monthly violations

ATTACHEMENTI
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan WWTP(NCO021873)
DMR Data(111/2020-12/31/2022)
SUMMER MONTHS
Effluent BOD Effluent TSS Effluent NH3-N Effluent Fecal Effluent NH3-N
Date mg/L mg/L mg/I #/100 ml Date mg/L
1/2/2020 5.70 12.00 6.53 3.10 4/1/2020 3.54
1/3/2020 34.00 34.00 1.11 10.00 4/7/2020 1.57
1/6/2020 1.00 4/8/2020 0.55
1/7/2020 4.00 7.30 <1.0 4/14/2020 8.68
1/8/2020 <2.0 4.80 127.00 4/15/2020 5.98
1/14/2020 5.90 16.00 2420.00 4/21/2020 4.08
1/15/2020 20.00 20.00 4.76 <1.0 4/22/2020 <0.04
1/16/2020 2.00 4/28/2020 3.70
1/21/2020 <2.0 3-60 0.12 4.10 4/29/2020 0.24
1/22/2020 <2.0 7.90 26.20 5/5/2020 0.14
1/23/2020 14.50 5/6/2020 3 65
1/27/2020 1.00 5/12/2020 0.05
1/28/2020 <2.0 9.90 22.60 5/13/2020 0.11
1/29/2020 2.70 4.50 0.10 20.10 5/19/2020 6.34
2/3/2020 1.00 5/20/2020 2.75
2/4/2020 6.30 10.00 7.85 1.00 5/26/2020 2.23
2/5/2020 <2.0 3.50 3.10 5/27/2020 3.94
2/10/2020 7.40 5/30/2020 5.00
2/11/2020 21.00 23.00 5.31 136.00 6/3/2020 4.93
2/12/2020 25.00 20.00 1.00 6/4/2020 0.50
2/18/2020 7.90 22.00 8.66 <1.0 6/9/2020 0.35
2/19/2020 14.00 21.00 2420.00 6/10/2020 0.19
2/20/2020 <1.0 6/16/2020 4.22
2/24/2020 <1.0 6/17/2020 10.90
2/25/2020 25.00 24.00 6.98 6/23/2020 4.55
2/26/2020 8.40 9.40 0.49 1.00 6/24/2020 2.04
2/27/2020 <1.0 7/1/2020 4.25
3/2/2020 <1.0 7/2/2020 0.34
3/3/2020 5.10 9.50 <1.0 7/7/2020 0.25
3/4/2020 4.30 8.20 7.40 7/8/2020 0.25
3/9/2020 <1.0 7/14/2020 0.61
3/10/2020 2.30 6.80 0.52 3.10 7/15/2020 0.41
3/11/2020 2.30 6.10 1.00 7/21/2020 0.51
3/16/2020 <1.0 7/23/2020 0.68
3/17/2020 4.70 9.80 0.91 <1.0 7/28/2020 4.55
3/18/2020 3.90 4.40 <1.0 7/29/2020 2.53
3/23/2020 <1.0 8/4/2020 13.20
3/24/2020 <2.0 <2.0 1.62 2.00 8/5/2020 13.60
3/25/2020 45.00 51.00 2420.00 8/11/2020 3.20
3/30/2020 <1.0 8/12/2020 0.16
3/31/2020 8.20 7.00 7.17 <1.0 8/18/2020 1.63
4/1/2020 10.00 8.60 3.54 146.00 8/19/2020 0.23
4/6/2020 2.00 8/25/2020 1.81
4/7/2020 11.00 30.00 1.57 <1.0 8/26/2020 0.51
4/8/2020 6.20 7.30 0.55 520 9/1/2020 3.29
4/14/2020 16.00 23.00 8.68 2420.00 9/2/2020 4.87
4/15/2020 8.30 12.00 5.98 2420.00 9/8/2020 0.56
4/16/2020 <1.0 9/9/2020 0.17
4/21/2020 8.60 8.00 4.08 <1.0 9/15/2020 0.89
4/22/2020 3.90 5.40 <0.04 9.70 9/16/2020 0.24
4/23/2020 3.10 9/22/2020 0.18
4/27/2020 2.00 9/23/2020 0.36
4/28/2020 7.40 6.30 3.70 2.00 9/29/2020 0.09
4/29/2020 4.70 6.40 0.24 1.00 9/30/2020 0.11
5/4/2020 8.50 10/6/2020 0.11
5/5/2020 3.10 3.50 0.14 1.00 10/7/2020 0.14
5/6/2020 8.70 19.00 3.65 5.20 10/13/2020 4.55
5/11/2020 <1.0 10/14/2020 0.63
5/12/2020 <2.0 4.40 0.05 <1.0 10/20/2020 0.09
F�5/13/2020 <2.0 2.90 0.11 <1.0 10/21/2020 0.08
5/18/2020 1.00 10/27/2020 2.88
5/19/2020 48.00 83.00 6.34 2420.00 10/28/2020 0.18
5/20/2020 31.00 43.00 2.75 4/6/2021 0.10

ATTACHEMENT I
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan WWTP(NC0021873)
DMR Data(1/1/2020-12/31/2022)
SUMMER MONTHS
Effluent BOD Effluent TSS Effluent NH3-N Effluent Fecal Effluent NH3-N
Date m /L mg/L mg/I #/100 ml Date m /L
5/21/2020 2420.00 4/7/2021 0.05
5/26/2020 15.00 21.60 4/13/2021 0.65
5/26/2020 23.00 2.23 4/14/2021 0.12
5/27/2020 11.00 24.00 3.94 2420.00 4/20/2021 0.10
5/28/2020 2420-00 4/21/2021 0.33
5/29/2020 <2.0 4/27/2021 0.94
5/30/2020 8.40 11.60 5.00 4/28/2021 0.13
6/2/2020 4.10 5/4/2021 10.20
6/3/2020 6.40 14.00 4.93 3.10 5/5/2021 9.72
6/4/2020 4.70 6.60 0.50 2.00 5/11/2021 0.15
6/9/2020 2.80 2.60 0.35 <1.0 5/12/2021 0.18
6/10/2020 <2.0 3.20 0.19 1.00 5/19/2021 0.07
6/11/2020 <1.0 5/24/2021 0.05
6/15/2020 <1.0 5/25/2021 0.56
6/16/2020 11.00 12.00 4.22 2420.00 5/26/2021 3.19
6/17/2020 70.00 28.00 10.90 6/1/2021 7.54
6/18/2020 2420.00 6/2/2021 0.87
6/22/2020 <1.0 6/8/2021 7.02
6/23/2020 9.40 6.90 4.55 57.60 6/9/2021 7.46
6/24/2020 3.10 7.70 2.04 1.00 6/15/2021 5.17
6/29/2020 <1.0 6/16/2021 7.57
6/30/2020 <1.0 6/22/2021 4.67
7/1/2020 8.40 21.00 4.25 <1.0 6/23/2021 5.53
7/2/2020 2.20 5,70 0.34 6/29/2021 1.46
7/6/2020 <1.0 6/30/2021 0.41
7/7/2020 3.20 3.90 0-25 1.00 7/6/2021 0.22
7/8/2020 2.90 <2.5 0.25 <1.0 7/7/2021 1.83
7/13/2020 <1.0 7/13/2021 7.20
7/14/2020 5.00 8.60 0.61 3.10 7/14/2021 4.60
7/15/2020 4.80 5.30 0.41 4.10 7/20/2021 7.64
7/20/2020 <1.0 7/21/2021 7.92
7/21/2020 4.40 3.70 0.51 <1.0 7/27/2021 1.02
7/23/2020 4.40 5.50 0.68 2420.00 7/28/2021 0.23
7/27/2020 <1.0 8/3/2021 0.12
7/28/2020 6.30 5.80 4.55 1.00 8/4/2021 0.10
7/29/2020 7.40 17.00 2.53 <1.0 8/10/2021 7.35
8/3/2020 2.00 8/11/2021 2.38
8/4/2020 25.00 17.00 13.20 8/17/2021 12.76
8/5/2020 24.00 20.00 13.60 18.30 8/18/2021 12.88
8/6/2020 <1.0 8/24/2021 0.13
8/10/2020 <1.0 8/25/2021 0.27
8/11/2020 3.30 8.00 3.20 1.00 8/31/2021 0.45
8/12/2020 4.50 3.10 0.16 1.00 9/1/2021 0.13
8/17/2020 <1.0 9/7/2021 0.16
8/18/2020 6.70 17.00 1.63 2.00 9/8/2021 20.68
8/19/2020 3.20 3.50 0.23 1.00 9/14/2021 0.13
8/24/2020 4.10 9/21/2021 1.27
8/25/2020 3.10 7.70 1.81 7.50 9/21/2021 4.79
8/26/2020 5.00 3.90 0.51 1.00 9/22/2021 0.63
8/31/2020 <1.0 9/28/2021 0.13
9/1/2020 8.80 11.00 3.29 3.10 10/5/2021 0.10
9/2/2020 8.70 9.60 4.97 2.00 10/6/2021 0.34
9/8/2020 <2.0 3-40 0.56 <1.0 10/12/2021 0.09
9/9/2020 2.50 3.00 0.17 4.10 10/13/2021 0.13
9/10/2020 1.00 10/19/2021 0.13
9/14/2020 3.10 10/20/2021 0.08
9/15/2020 3.50 2.50 0.89 3.10 10/26/2021 4.27
9/16/2020 3.40 5.30 0.24 1.00 10/27/2021 1.21
9/21/2020 47.30 4/4/2022 0.04
9/22/2020 3.30 5.10 0.18 23.30 4/6/2022 0.11
9/23/2020 3.401 3.40 0.36 6.30 1 4/11/2022 1.87
9/28/2020 1 6.30 4/12/2022 0.09
9/29/2020 <2.0 <2.51 0.09 <1.0 4/13/2099 0.20

ATTACHEMENT I
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan WWTP(NC0021873)
DMR Data(1/1/2020-12/31/2022)
SUMMER MONTHS
Effluent BOD Effluent TSS Effluent NH3-N Effluent Fecal Effluent NH3-N
Date mg/L mg/L m /I #/100 ml Date m /L
9/30/2020 <2.0 <2.5 0.11 2-00 4/19/2022 0.15
10/5/2020 2.00 4/20/2022 3.36
10/6/2020 <2.0 <2.5 0.11 2.00 4/26/2022 0.36
10/7/2020 <2.0 3.60 0.14 <1.0 4/27/2022 0.19
10/13/2020 12.00 16.00 4.55 2420.00 5/3/2022 3.82
10/14/2020 12.00 16.00 0.63 12.10 5/4/2022 2.07
10/15/2020 12.10 5/10/2022 5.45
10/19/2020 <1.0 5/11/2022 1.78
10/20/2020 2.40 3.30 0.09 2.00 5/18/2022 1.04
10/21/2020 <2.0 3.50 0.08 4.10 5/23/2022 0.86
10/27/2020 7.10 6.90 2.88 4.10 5/24/2022 3.63
10/28/2020 2.20 3.40 0.18 63.80 5/25/2022 3.77
10/29/2020 2420,00 5/31/2022 0.59
11/2/2020 9.70 6/1/2022 0.59
11/3/2020 <2.0 3.80 0.18 17.10 6/7/2022 0.82
11/4/2020 <2.0 4.00 5.20 6/8/2022 0.20
11/9/2020 3.00 6/14/2022 0.23
11/10/2020 2.10 3.70 0.14 184.00 6/15/2022 0.06
11/11/2020 5.50 7.80 2420.00 6/21/2022 0.28
11/16/2020 2420.00 6/22/2022 0.14
11/17/2020 4.40 4.90 0.47 2420.00 6/28/2022 U22
11/18/2020 <2.0 3.80 1210.00 6/29/2022 0.42
11/19/2020 2.00 7/5/2022 0.30
11/23/2020 38.90 7/6/2022 0.18
11/24/2020 <2.0 4.70 0.08 25.60 7/12/2022 4.00
11/25/2020 <2.0 4.10 10.90 7/13/2022 0.23
12/1/2020 19.00 21.00 3.18 7/19/2022 0.06
12/2/2020 13.00 23.00 10.80 7/20/2022 0.19
12/3/2020 22.60 7/26/2022 0.09
12/4/2020 9.80 7/27/2022 0.24
12/8/2020 2.20 7.90 5.20 8/2/2022 0.22
12/9/2020 4.60 9.90 1.59 9.70 8/3/2022 0.10
12/10/2020 12.20 8/9/2022 0.16
12/14/2020 7.40 8/10/2022 0.08
12/15/2020 20.00 27.00 8/16/2022 0.08
12/16/2020 172.00 8/17/2022 0.08
12/17/2020 3.30 10.00 4.22 2.00 8/23/2022 2.75
12/21/2020 4.10 8/24/2022 0.33
12/22/2020 3.70 15.00 0.07 2.00 8/30/2022 12.40
12/23/2020 3.80 5.70 6.30 8/31/2022 7.12
12/28/2020 3.10 9/7/2022 1.22
12/29/2020 2.90 6.60 6.30 9/8/2022 0.20
12/30/2020 2.80 6.10 0.06 27.50 9/13/2022 5.07
1/4/2021 <1.0 9/14/2022 0.11
1/5/2021 2.10 4.00 <0.04 1.00 9/20/2022 0.11
1/6/2021 <2.0 4.50 3.00 9/21/2022 0.14
1/11/2021 2.00 9/27/2022 0.17
1/12/2021 13.00 17.00 3.76 1.00 9/28/2022 0.14
1/13/2021 10.00 7.50 5.17 3.10 10/4/2022 0.25
1/19/2021 5.10 6.90 3.30 1.00 10/5/2022 0.08
1/20/2021 3.30 9.60 <1.0 10/11/2022 0.08
1/21/2021 2.00 10/12/2022 0.07
1/26/2020 <2.0 3.70 0.87 10/18/2022 0.13
1/25/2021 2.00 10/19/2022 0.15
1/27/2021 44.00 44.00 2.00 10/25/2022 1.06
1/28/2021 2420.00 10/26/2022 0.12
2/2/2021 21.00 12.00 4.71 4.10
2/3/2021 14.00 10.00 4.10
2/4/2021 2.00
2/9/2021 11.00 9.20 3.65 2.00
2/10/2021 <2.01 5.40 <1.0
2/11/2021 1 1 1 4.10
2/16/2021 18.00 11-001 2.911 23.30

ATTACHEMENT I
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan WWTP(NC0021873)
DMR Data(1/1/2020-12/31/2022)
SUMMER MONTHS
Effluent BO D Effluent T55 Effluent NH3-N Effluent Fecal Effluent NH3-N
Date mg/L mg/L mg/I #/100 ml Date mg/L
2/17/2021 22.00 21.00 4.10
2/18/2021 3.10
2/22/2021 4.20 15.40 4.10
2/23/2021 14.00 12.00 1.34 3.10
2/24/2021 13.00 25.00 4.10
3/1/2021 1.00
3/2/2021 <1.0
3/3/2021 3.00 3.80 0.15 2.00
3/4/2021 2.30 3.50
3/8/2021 2.00
3/9/2021 1.00
3/10/2021 2.30 3.30 0.06 2.00
3/11/2021 2.60 3.40
3/15/2021 <1.0
3/16/2021 2.20 5.90 1.71 <1.0
3/17/2021 3.00 4.70 <1.0
3/23/2021 <1.0
3/24/2021 4.90 7.10 1.18 <1.0
3/25/2021 5.20 15.00 1.00
3/30/2021 5.20 5.00 3.43 11.00
3/31/2021 2.80 6.60 0.07 1.00
4/1/2021 9.70
4/5/2021 1.00
4/6/2021 <2.0 <2.5 0.10 1.00
4/7/2021 <2.0 <2.5 0.05 2.00
4/12/2021 9.70
4/13/2021 3.70 3.60 0.65 8.60
4/14/2021 <2.0 3.40 0.12 8.60
4/19/2021 1.00
4/20/2021 <2.0 <2.5 0.10 2.00
4/21/2021 3.30 <2.5 0.33 4.10
4/26/2021 276.00
4/27/2021 3.70 3.50 0.94 4.10
4/28/2021 3.70 2.60 0.13 26.20
5/3/2021 <1.0
5/4/2021 47.00 30.00 10.20
5/5/2021 23.00 16.00 9.72 <1.0
5/6/2021 3.00
5/10/2021 <1.0
5/11/2021 4.60 4.50 0.15 2.00
5/12/2021 4.10 3.20 0.18 5.20
5/17/2021 3.00
5/18/2021 1.00
5/19/2021 4.70 3.70 0.07 4.10
5/24/2021 2.60 2.90 0.05 <1.0
5/25/2021 4.50 3.00 0.56 387.00
5/26/2021 6.50 4.901 3.19 2420.00
6/1/2021 12.00 10.00 7.54 1.00
6/2/2021 5.00 5.10 0.87 13.10
6/3/2021 <1.0
6/7/2021 1.00
6/8/2021 24.00 23.00 7.02 2420.00
6/9/2021 20.00 16.00 7.46 1.00
6/15/2021 20.00 29.00 5.17 2420.00
6/16/2021 15.00 13.00 7.57 326.00
6/17/2021 2420.00
6/18/2021 2.00
6/21/2021 3.00
6/22/2021 9.40 13.00 4.67 165.00
6/23/2021 12.00 11.00 5.53 <1.0
6/28/2021 <1.0
6/29/2021 <2.0 2.50 1.46 1.00
6/30/2021 3.70 3.40 0.41 1.00

ATTACHEMENT I
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan WWTP(NC0021873)
DMR Data(1/1/2020-12/31/2022)
SUMMER MONTHS
Effluent ROD Effluent TSS Effluent N H3-N Effluent Fecal Effluent N H3-N
Date mg/L mg/L mg/I #1100 ml Date mg/L
7/6/2021 7.10 4.90 0.22 5.20
7/7/2021 3.90 4.00 1.83 <1.0
7/8/2021 <1.0
7/12/2021 2.00
7/13/2021 5.40 12.00 7.20 <1.0
7/14/2021 4.30 6.60 4.60 1.00
7/20/2021 13.00 10.00 7.64 <1.0
7/21/2021 13.00 11.00 7.92 1.00
7/22/2021 <1.0
7/26/2021 1.00
7/27/2021 4.40 <2.5 1.02 3.10
7/28/2021 4.70 2.50 0.23 17.50
8/2/2021 <1.0
8/3/2021 2.80 2.90 0.12 <1.0
8/4/2021 2.70 3.80 0.10 3.10
8/9/2021 3.10
8/10/2021 9.40 13.00 7.35 3.10
8/11/2021 11.00 5.00 2.38
8/12/2021 2.00
8/17/2021 31.00 25.00 12.76 2420.00
8/18/2021 23.00 57.00 12.88 2420.00
8/19/2021 2420.00
8/20/2021 12.20
8/23/2021 2.00
8/24/2021 7.30 5.60 0.13 7.50
8/25/2021 9.60 5.90 0.27 19.30
8/30/2021 <1.0
8/31/2021 4.80 3.301 0.45 15.50
9/1/2021 9A0 7.10 0.13 <1.0
9/7/2021 3.20 4.30 0.16
9/8/2021 6.00 5.70 20.68 2420.00
9/10/2021 205.00
9/11/2021 1.00
9/13/2021 5.20
9/14/2021 5.30 4.40 0.13 28.10
9/15/2021 1.00
9/21/2021 <2.0 6.10 1.27
9/20/2021 <1.0
9/21/2021 4.70 17.00 4.79 5.20
9/22/2021 16.00 3.80 0.63 <1.0
9/27/2021 17.30
9/28/2021 3.50 3.10 0.13 13.50
9/29/2021 2.90 1.00
10/4/2021 2.00
10/5/2021 3.10 3.80 0.10 5.20
10/6/2021 4.00 4.80 0.34 4.10
10/11/2021 1.00
10/12/2021 <2.0 4.10 0.09 1.00
10/13/2021 <2.0 3.80 0.13 2.00
10/18/2021 2.00
10/19/2021 <2.0 3.90 0.13 3.10
10/20/2021 2.60 11.00 0.08 4.10
10/25/2021 2.00
10/26/2021 <2.0 9.80 4.27
10/27/2021 <2.0 5.10 1.21 2.00
10/28/2021 8.50
11/1/2021 1.00
11/2/2021 2.40 4.70 <0.04 <1.0
11/3/2021 4.10 3.40 1.00
11/8/2021 1.00
11/9/2021 <2.0 3.60 <0.04 2.00
11/10/2021 3.60 5.10 0.04 10.90
11/15/2021 1.00

ATTACHEMENTI
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan W WTP(NC0021873)
DMR Data(1/1/2020-12/31/2022)
SUMMER MONTHS
Effluent BOD Effluent TSS Effluent NH3-N Effluent Fecal Effluent NH3-N
Date m L mg/L mg/I #/100 ml Date m L
11/16/2021 1.00
11/17/2021 <2.0 2.60 0.21 5.20
11/22/2021 3.00 3.10 3.10
11/20/2021 2.50 5.80
11/23/2021 <2.0 4.00 0.07 4.10
11/24/2021 <2.0 4.80 1.00
11/29/2021 4.10
11/30/2021 <2.0 4.10 0.09 4.00
12/1/2021 3.40 4.20 <1.0
12/6/2021 <1.0
12/7/2021 2.60 3.60 0.06 <1.0
12/8/2021 3.00 3.70 <1.0
12/13/2021 2.00
12/14/2021 <1.0
12/15/2021 3.30 5.40 0.16 1.00
12/20/2021 3.00 4.20 <1.0
12/21/2021 2.60 3.20 0.61 <10
12/22/2021 4.20 5.60 5.20
12/27/2021 <1.0
12/28/2021 3.20 7.10 0.08 1.00
12/29/2021 3.50 3.60 1.00
1/4/2022 11.00 14.00 4.67 4.10
1/5/2022 3.20 6.60 12.10
1/6/2022 3.10
1/10/2022 3.10
1/11/2022 3.60 3.90 0.27 2.00
1/12/2022 3.80 5.30 7.30
1/18/2022 2.40 4.60 0.04 2.00
1/19/2022 9.60 10.00 <1.0
1/20/2022 <1.0
1/24/2022 5.20
1/25/2022 <2.0 3.10 0-06 <1.0
1/26/2022 2.20 5.30 T50
1/31/2022 4.10
2/1/2022 3.10 <3.3 0.04 3.00
2/2/2022 3.30 4.10 <1.0
2/7/2022 3.10
2/8/2022 4.60 4.70 0.10 7.30
2/9/2022 4.50 5.10 9.80
2/14/2022 9.80
2/15/2022 4.40 5.80 0.16 6.30
2/16/2022 3.80 3.60 8.60
2/21/2022 5.00
2/22/2022 4.30 10.00 0.06 4.10
2/23/2022 95.00 260.00 2420.00
2/26/2022 12.30
2/28/2022 2.00
3/1/2022 5.40 12.00 2.00
3/2/2022 2.90 5.10 4.10
3/7/2022 <0.10 1.00
3/8/2022 13.00 16.00 3.47 <1.0
3/9/2022 28.00 26.00 2420.00
3/11/2022 4.30
3/14/2022 2.00
3/15/2022 6.00 6.50 0.27 2.00
3/16/2022 2.80 5.50 2.00
3/21/2022 1.00
3/22/2022 2.60 4.60 0.15 1.00
3/23/2022 2.00 4.30 3.10
3/28/2022 <1.0
3/29/2022 4.10
3/30/2022 <2.0 <2.5 0.06 1.00
4/4/2022 <2.0 <2.5 0.04 <1.0

ATTACHEMENTI
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan WWTP(NC0021873)
DMR Data(1/1/2020-12/31/2022)
SUMMER MONTHS
Effluent BO D Effluent TSS Effluent NH3-N Effluent Fecal Effluent NH3-N
Date m /L mg/L mg/I #/100 ml Date mg/L
4/5/2022 2.00
4/6/2022 <2.0 2.90 0.11 7.40
4/11/2022 4.60 5.90 1.87 1.00
4/12/2022 <2.0 <2.6 0.09 12.20
4/13/2022 <2.0 <2.5 0.20 3.00
4/18/2022 2420.00
4/19/2022 4.30 2.90 0.15
4/20/2022 12.00 12.00 3.36 2.00
4/22/2022 <1.0
4/25/2022 3.00
4/26/2022 3.20 3.90 0.36 2.00
4/27/2022 3.30 2.70 0.19 2.00
5/3/2022 9.70 9.50 3.82 649.00
5/4/2022 8.60 4.50 2.07 2.00
5/5/2022 1.00
5/9/2022 2420.00
5/10/2022 10.00 13.00 5.45 4.10
5/11/2022 7.20 11.00 1.78 238.00
5/12/2022 2.00
5/16/2022 2.00
5/17/2022 2.00
5/18/2022 19.00 7.20 1.04 14.50
5/23/2022 2.40 8.80 0.86 2420.00
5/24/2022 47.00 82.00 3.63
5/25/2022 12.00 19.00 3.77 9.40
5/27/2022 2.00
5/31/2022 9.00
5/31/2022 9.50 7.40 0.59 2.00
6/1/2022 15.00 9.20 0.59 2.00
6/2/2022 199.00
6/6/2022 5.20
6/7/2022 5.30 2.80 0.82 <1.0
6/8/2022 460 3.50 0.20 <1.0
6/13/2022 <1.0
6/14/2022 2.10 2.60 0.23 <1.0
6/15/2022 <2.0 <2.5 0.06 510
6/20/2022 2.00
6/21/2022 2.50 4.00 0.28 2.00
6/22/2022 <2.0 2.80 0.14 <1.0
6/27/2022 1.00
6/28/2022 <2.0 <2.5 0.22 3.10
6/29/2022 2.10 4.40 0.42 <1.0
7/5/2022 <2.0 <2.5 0.30 4.10
7/6/2022 2.60 4.30 0.18 <1.0
7/7/2022 <1.0
7/11/2022 3.00
7/12/2022 8.20 5.50 4.00 5.20
7/13/2022 2.70 2.90 0.23 13.50
7/18/2022 12.10
7/19/2022 2.60 <2.5 0.06 9.70
7/20/2022 3-00 7.10 0.19 6.30
7/25/2022 2,00
7/26/2022 2.20 4.00 0.09 <1.0
7/27/2022 2.30 3.20 0.24 1.00
8/1/2022 3.10
8/2/2022 2.70 3.50 0.22 16.10
8/3/2022 <2.0 <2.5 0.10 2.00
8/8/2022 2.00
8/9/2022 <2.0 3.50 0.16 2.00
8/10/2022 2.90 6.20 0.08 1.00
8/15/2022 2.00
8/16/2022 <2.0 <2.5 0.08 6.30
8/17/2022 <2.0 2.80 0.08

ATTACHEMENTI
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan W WTP(NC0021873)
DMR Data(1/1/2020-12/31/2022)
SUMMER MONTHS
Effluent BOD Effluent TSS Effluent NH3-N Effluent Fecal Effluent NH3-N
Date mg/L mg/L mg/I #/100 ml Date mg/L
8/18/2022 210.00
8/23/2022 12.00 10.00 2.75 56.50
8/24/2022 6.10 6.90 0.33 16.00
8/25/2022 4.10
8/29/2022 2.00
8/30/2022 15.00 11.00 12.40 95.90
8/31/2022 26.00 24.00 7.12 196.00
9/6/2022 2420.00
9/7/2022 5.20 9.20 1.22 2420.00
9/8/2022 2.60 3.60 0.20 179.00
9/9/2022 10.90
9/13/2022 25.00 32.00 5.07 6.30
9/14/2022 2.10 4.30 0.11 1.00
9/15/2022 1.00
9/19/2022 <1.0
9/20/2022 <2.0 7.60 0.11 4.10
9/21/2022 2.80 3.10 0.14 161.00
912612022 <1.0
9/27/2022 2.40 4.10 0.17 2.00
9/28/2022 2.10 4.10 0.14 3.10
10/4/2022 4.20 3.90 0.25 7.40
10/5/2022 2.80 3.501 0.08 10.90
10/6/2022 <1.0
10/10/2022 2.00
10/11/2022 2.50 <2.5 0.08 3.00
10/12/2022 2.60 6.90 0.07 1.00
10/17/2022 2420.00
10/18/2022 2.90 5.90 0.13 2.00
10/19/2022 3.20 5.80 0.15 5.20
10/24/2022 5.10
10/25/2022 <2.0 4.90 1.06 7.50
10/26/2022 <2.0 10.00 0.12 1.00
10/31/2022 21.60
11/1/2022 2.30 <2.5 0.45 1.00
11/2/2022 13.00 13.00 <1.0
11/7/2022 2.00
11/8/2022 <2.0 7.80 0.14 <1.0
11/9/2022 <2.0 2.90 <1.0
11/14/2022 2.00
11/15/2022 2.20 5.00 0.09 3.10
11/16/2022 <2.0 5.30 3.00
11/21/2022 8.60
11/22/2022 3.90 7.60 0.04 6.30
11/23/2022 <2.0 5.80 24.00
11/28/2022 <1.0
11/29/2022 <2.0 3.40 0.08 4.10
11/30/2022 <2.0 5.20
12/1/2022 <1.0
12/5/2022 6.30
12/6/2022 5.90 16.00 0.08 6.30
12/7/2022 5.20 12.00 <1.0
12/12/2022 8.60
12/13/2022 <2.0 3.00 0.24 13.50
12/14/2022 <2.0 3.40 13.50
12/19/2022 <1.0
12/20/2022 <2.0 12.00 0.94 1.00
12/21/2022 5.30 12.00 <1.0
12/27/2022 <2.0 9.10 2.00
12/28/2022 2.70 8.90 1.08 <1.0
12/29/2022 1.00

ATTACHEMENT I
REQUEST FOR REDUCED MONITORING FOR EXCEPTIONALLY PERFORMING FACILITIES
Town of Mayodan WWTP(NC0021873)
DMR Data(1/1/2020-12/31/2022)
SUMMER MONTHS
Effluent BOD Effluent TSS Effluent NH3-N Effluent Fecal Effluent NH3-N
Date mg/L mg/L mg/I #/100 ml Date m L
Average 8.6 10.3 7.7 Average 2.2
NPDES Monthly NPDES Monthly
Avg Limit 30 30 200 Avg Limit 16
50%of Monthly 50%of Monthly
Average Limit 15 15 100 Average Limit 8
200%of Weekly 200%of Weekly
Avg 90 90 800 Avg 70
#samples>
200%of Weekly #samples>200%
Avg 1 11 35 of Weekly Avg 0