NC0021121_Fact Sheet_20200922

Fact Sheet
NPDES Permit No. NCO021121
Permit Writer/Email Contact Gary Perlmutter, [e-mail]:
Date: September 15, 2020
Division/Branch: NC Division of Water Resources / NPDES Municipal Permitting Unit
Fact Sheet Template: Version 09Jan2017
Permitting Action:
❑X Renewal
❑ Renewal with Expansion
❑ New Discharge
❑ Modification (Fact Sheet should be tailored to mod request)
Note: A complete application should include the following:
• For New Dischargers, EPA Form 2A or 2D requirements, Engineering Alternatives Analysis, Fee
• For Existing Dischargers (POTW), EPA Form 2A, 3 effluent pollutant scans, 4 2nd species WET
tests.
• For Existing Dischargers (Non-POTW), EPA Form 2C with correct analytical requirements based
on industry category.
Complete applicable sections below. If not applicable, enter NA.
1. Basic Facility Information
Facility Information
Applicant/Facility Name:
City of Mount Airy/Mount Airy WWTP
Applicant Address:
P.O. Box 70, Mount Airy, NC 27030
Facility Address:
1750 Andy Griffith Parkway South, Mount Airy, NC 27030
Permitted Flow:
7.0 MGD
Facility Type/Waste:
MAJOR Municipal; 99% domestic, 1% industrial'
Facility Class:
Grade IV
Treatment Units:
Screening, Grit Removal, Primary Clarifiers, Trickling Filters,
Aeration, Final Clarifiers, Chlorination, Dechlorination, Cascade
Aeration
Pretreatment Program (Y/N)
Yes
County:
Surry
Region
Winston-Salem
'From permitted industrial flow of 0.065 MGD.
Briefly describe the proposed permitting action and facility background: The City of Mount Airy has
applied for an NPDES permit renewal for its Mount Airy WWTP, received by DWR on August 24, 2018.
This was followed by test results of four additional parameters (Antimony, Beryllium, Thallium and Total
Phenolic Compounds) not included in the October 2015 Primary Pollutant Analysis (PPA), received on
Page 1 of 13

September 25, 2018. Review of the application found it complete with three PPAs (sampled July 2015,
October 2016, and January 2017) and four 2nd species toxicity test reports (sampled July 2015, October
2016, January 2017, and April 2018).
This 7.0 MGD facility serves a population of 10,347 residents in the City of Mount Airy. The WWTP treats
a combination of domestic and industrial wastewater with a pretreatment program involving one Significant
Industrial User (SIU): Hanesbrands, Inc. (textiles: Sock Manufacturing) listed in its application. However,
Hanesbrands closed in December 2019. Mount Airy has a new SIU: Professional Rental Service
(commercial laundry facility) with effective date February 1, 2020, and permitted flow 0.065 MGD.
2. Receiving Waterbody Information
Receiving Waterbody Information
Outfalls/Receiving Stream(s):
Outfall 001/Ararat River
Stream Segment:
12-72-(4.5)
Stream Classification:
C
Drainage Area (mi2):
75.2
Summer 7Q10 (cfs)
14.9
Winter 7Q10 (cfs):
31
30Q2 (cfs):
Average Flow (cfs):
90
IWC (% effluent):
42%
303(d) listed/parameter:
Turbidity
Subject to TMDL/parameter:
State-wide Mercury TMDL
Basin/Sub-basm/HUC:
Yadkin Pee Dee/03-07-03/03040101
USGS Topo Quad:
B 16NE/Mt Airy South, NC
The receiving stream segment of Ararat River is impaired due to Turbidity per the 2018 NC 303(d) list.
According to the 2008 Yadkin - Pee Dee River Basin Plan, potential sources include stormwater runoff and
impervious surfaces. The Basin Plan recommends restoration plans for watersheds impaired or impacted
by Turbidity violations in Yadkin River headwaters, including the watershed wherein the receiving water
lies.
3. Effluent Data Summary
Effluent data for Outfall 001 is summarized in Table 1 for the period of April 2016 through March 2020.
Table 1. Effluent Data Summary Outfall 001.
Parameter
Units
Average
Max
Min
Permit Limit'
Flow'
MGD
1.61
11.04
0.57
Page 2 of 13

Parameter
Units
Average
Max
Min
Permit Limit'
BOD5
mg/L
3.4
32.2
< 2.0
MA = 30.0
WA = 45.0
BOD removal
%
98.6
99.5
96.3
> 85
TSS
mg/L
4.2
61.5
2.34
MA = 30.0
WA = 45.0
TSS removal
%
98.5
99.5
96.3
> 85
NH3-N (Apr 1 - Oct 31)
mg/L
0.3
15.2
< 0.1
MA = 13.0
WA = 35.0
NH3-N (Nov 1 - Mar 31)
mg/L
0.2
3.3
< 0.1
DO (Apr 1 - Oct 31)
mg/L
8.8
18.6
6.5
DA > 5.0
DO (Nov 1 - Mar 31)
mg/L
10.6
18.0
6.9
Fecal Coliform
(geometric mean)
#/100 mL
8
> 2420
< 1
MA = 200
WA = 400
TRC
µg/L
12
28
0
DM = 28 3
pH
S.U.
7.1
7.7
6.3
6.0 - 9.0
Temperature
°C
17
27
5
Total Nitrogen
(NO2 + NO3 + TKN)
mg/L
8.81
18.60
6.50
Total Phosphorus
mg/L
2.39
10.1
0.2
Conductivity
µmhos/cm
439
629
208
Oil & Grease
mg/L
All values < 5
Total Copper
µg/L
14
36
9
Total Silver
µg/L
2
<5
<1
Total Zinc
µg/L
110
520
31
Chloride
mg/L
46.8
32.2
78.7
' MA = Monthly Average, WA = Weekly Average, DM = Daily Maximum; DA = Daily Average.
2 Average for CY2019 = 1.62 MGD, 23% of design flow.
3 Values < 50 µg/L considered compliant.
4. Instream Data Summary
Instream monitoring may be required in certain situations, for example: 1) to verify model predictions when
model results for instream DO are within 1 mg/L of instream standard at full permitted flow; 2) to verify
model predictions for outfall diffuser; 3) to provide data for future TMDL; 4) based on other instream
concerns. Instream monitoring may be conducted by the Permittee, and there are also Monitoring Coalitions
established in several basins that conduct instream sampling for the Permittee (in which case instream
monitoring is waived in the permit as long as coalition membership is maintained).
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If applicable, summarize any instream data and what instream monitoring will be proposed for this permit
action: The current permit requires instream monitoring for Dissolved Oxygen (DO) and Temperature.
Three instream monitoring locations are in the current permit: one upstream at NC Hwy 52, and two
downstream: 1) approximately 1.0 mile below the discharge before the confluence with Stewarts Creek,
and 2) approximately 6.0 miles below the discharge before the confluence with Caddle Creek. The second
downstream location has been carried over from the previous permit. Instream sampling is provisionally
waived as the Permittee is a member of the Yadkin -Pee Dee River Basin Association (YPDRBA). Instream
monitoring data are available from YPDRBA stations Q1500000 — Ararat River at NC 52 near Mt Airy
(same as the permit upstream location) and Q1935000 — Ararat River at SR 2044 near Pilot Mountain, 14
river miles downstream from the discharge and downstream of the Pilot Mtn WWTP (NC0026646)
discharge.
Instream data were requested from the DWR Water Sciences Section's Monitoring Coalition Coordinator
for review. Data were reviewed from April 2016 through December 2019 and were compared against state
water quality standards where applicable. As the data were sampled synchronously at both locations, up- to
downstream differences were tested by paired two -sample t-test for means with the significance level (p-
value) set at 0.05. Instream data review findings for each parameter are summarized below.
Dissolved Oxygen (DO) — DO remains in the permit as a parameter of concern for aquatic life. The receiving
stream segment of the Ararat River is meeting the criteria for DO (instantaneous minima of 4 mg/L for
aquatic life in freshwater) according to the Final 2018 Integrated Report. Reviewed instream DO data
showed seasonal patterns of summer lows and winter highs. Instream summer minima were above the 5
mg/L daily average water quality standard for non -trout waters (15A NCAC 02B .0211) at both locations.
Downstream DO was higher (average = 8.5 mg/L; range: 6.5-11.7 mg/L) than that upstream (average = 8.2
mg/L; range: 6.3-11.8 mg/L), testing significantly higher on average (t-test, p < 0.0001). Concurrent
effluent DO averaged 9.2 mg/L, higher than either instream average with a range of 7.0-18.6 mg/L. Effluent
DO does not appear to negatively impact instream DO levels.
Temperature — Temperature remains in the permit as a parameter of concern for aquatic life. The receiving
stream segment of the Ararat River is meeting the criteria for Temperature (29°C for aquatic life in upper
piedmont and mountain waters) according to the Final 2018 Integrated Report. Reviewed instream
temperature data showed seasonal patterns of summer highs and winter lows at both locations. Downstream
temperature was slightly lower (average = 18.5 °C; range: 6.1-26.1 °C) than that upstream (average = 18.9
°C; range: 6.1-27.6 °C) and a statistically significant difference did exist (t-test,p < 0.0005). Temperature
maxima were below the water quality standard of 29°C for upper piedmont and mountain waters (15A
NCAC 02B .0211) at both locations. The highest upstream to downstream temperature increase was 1.5
°C, below the 2.8 °C increase standard. The concurrent effluent temperatures averaged higher overall at
19.2 °C with higher winter minima (range: 9-26 'Q.
Conductivity — Conductivity (Specific Conductance) is a parameter of concern due to industrial discharges;
however, this parameter is not in the permit for instream monitoring. Reviewed data from coalition
monitoring showed the downstream average of 90 µS/cm (range: 50-119 µS/cm) to be significantly lower
than the upstream average of 112 µS/cm (range: 50-165 µS/cm). Conductivity levels in both sites dropped
substantially in August -September 2018 from an average of 121 µS/cm (range: 70-165 µS/cm) to 61 µS/cm
(range: 50-88 µS/cm). Concurrent effluent Conductivity data (expressed as µmho/cm, which is equivalent
to µS/cm) averaged substantially higher at 452 µmho/cm (range: 275-573 µmho/cm). Comparisons of the
three data sets suggest that the effluent is not impacting the instream conductivity. Therefore, instream
conductivity monitoring is not needed and was not added to the permit.
Fecal Coliform — Fecal Coliform is a parameter of concern for aquatic life and human health. The
downstream coliform count geometric mean was 108 cfu/100 mL (range: 46-9200 cfu/100 mL), while the
upstream was 180 cfu/100 mL (range: 56-9800 cfu/100 mL). Concurrent effluent coliform counts were
substantially lower with a geometric mean of 8 cfu/100 mL (range: < 1-145 cfu/100 mL).
Page 4 of 13

Per the Division's 2002 Instream Conductivity and Fecal Coliform Monitoring Guidance, Fecal Coliform
monitoring is not required unless the receiving stream is either a Class B waterbody or is impaired due to
coliform. The receiving water is neither, so instream monitoring for coliform is not required and was not
added to the permit.
Is this facility a member of a Monitoring Coalition with waived instream monitoring (YIN): YES.
Name of Monitoring Coalition: Yadkin -Pee Dee River Basin Association.
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): From April 2015 through April
2020, one violation resulted in an action: a BOD weekly geometric mean exceedance of 426.44 cfu/100 mL
on 7/11/2015, resulting in an issuance of a Notice of Deficiency.
Summarize the compliance record with aquatic toxicity test limits and any second species test results (past
5 years): The facility passed 17 of 17 quarterly chronic toxicity tests from January 2016 through January
2020, as well as all four 2nd species tests, sampled in July 2015, October 2016, January 2017, and April
2018).
Summarize the results from the most recent compliance inspection: The most recent facility inspection,
conducted on 11/28/2018, reported no compliance issues. The most recent pretreatment compliance
inspection, conducted on 6/04/2019, also reported no compliance issues.
6. Water Quality -Based Effluent Limitations (WQBELs)
Dilution and Mixing Zones
In accordance with 15A NCAC 213.0206, 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/L for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
Ifpermit limits are more stringent than TBELs, describe how limits were developed: BOD limits are based
on a water quality model and shall be maintained in the permit.
Ammonia and Total Residual Chlorine Limitations
Limitations for ammonia are based on protection of aquatic life utilizing an ammonia chronic criterion of
1.0 mg/L (summer) and 1.8 mg/L (winter). Acute ammonia limits are derived from chronic criteria, utilizing
a multiplication factor of 3 for Municipals and a multiplication factor of 5 for Non -Municipals.
Page 5 of 13

Limitations for Total Residual Chlorine (TRC) are based on the NC water quality standard for protection
of aquatic life (17 µg/L) and capped at 28 µg/L (acute impacts). Due to analytical issues, all TRC values
reported below 50 µg/L are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal: Ammonia limits
in the permit are based on a water quality model for oxygen -consuming waste. Toxicity -based Ammonia
was reviewed in the attached Wasteload Allocation (WLA) sheet using the flow design of 7.0 MGD and
receiving stream low flows of summer 7Q10 = 14.9 cfs and winter 7Q10 = 31.0 cfs. The resulting allowable
concentrations were 2.1/6.3 mg/L monthly average/weekly average for summer, and 6.3/18.9 mg/L monthly
average/weekly average for winter. Because they are more stringent, the calculated toxicity -based limits
were added to the permit.
A review of DMR data from April 2015 through March 2020 against the proposed limits show that the
lowered summer limits can be met without difficulty. The ORC attributed the elevated values to cold
temperatures, and does not take issue with the proposed limits.
Ammonia-N (NH3-N) Proposed Limits
WkAvg Mo Avg WA Limit MA Limit
20
18
16
14
12
n� 10
E 8
1P
O,�
OHO
Oti1
O,y'1
ZN D,y�
O�
ati�
Oti0
1'1'ti
y4i�ti
Obo\N
15
C),til,�ti
1,1 y6
y
y�ti�ti
�,K'y
The current TRC limit of 28 µg/L was first established in the permit in 2004 as capped to protect against
acute impacts in the receiving water per the then new TRC policy. WLA calculations for TRC also cap the
allowable concentration at 28 µg/L. The current TRC limit has been maintained in the permit.
Reasonable Potential Analysis (RPA) for Toxicants
If applicable, conduct RPA analysis and complete information below.
The need for toxicant limits is based upon a demonstration of reasonable potential to exceed water quality
standards, a statistical evaluation that is conducted during every permit renewal utilizing the most recent
effluent data for each outfall. The RPA is conducted in accordance with 40 CFR 122.44 (d) (i). The NC
RPA procedure utilizes the following: 1) 95% Confidence Level/95% Probability; 2) assumption of zero
background; 3) use of '/2 detection limit for "less than" values; and 4) streamflows used for dilution
consideration based on 15A NCAC 2B.0206. Effective April 6, 2016, NC began implementation of
dissolved metals criteria in the RPA process in accordance with guidance titled NPDES Implementation of
Instream Dissolved Metals Standards, dated June 10, 2016.
Page 6 of 13

A reasonable potential analysis was conducted on effluent toxicant data collected from April 2016 through
January 2020. 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: Copper, Zinc.
• 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: Arsenic,
Beryllium, Cadmium, Chlorides, Total Phenols, Total Chromium, Cyanide, Lead, Molybdenum,
Nickel, Selenium, Silver.
• 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.
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.
Toxicily 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 facility is a Major POTW, and a chronic WET limit at
42% effluent will continue on a quarterly frequency. The WET limit is based on the Instream Waste
Concentration (IWC) as calculated from the design flow of 7.0 MGD and the receiving stream 7Q10s of
14.9 cfs (WET Permitting Limits and Monitoring Requirements guidance memo, 8/2/ 1999).
Mercury Statewide TMDL Evaluation
There is a statewide TMDL for mercury approved by EPA in 2012. The TMDL target was to comply with
EPA's mercury fish tissue criteria (0.3 mg/kg) for human health protection. The TMDL established a
wasteload allocation for point sources of 37 kg/year (81 lb/year), and is applicable to municipals and
industrial facilities with known mercury discharges. Given the small contribution of mercury from point
sources (-2% of total load), the TMDL emphasizes mercury minimization plans (MMPs) for point source
control. Municipal facilities > 2 MGD and discharging quantifiable levels of mercury (> 1 ng/L) will receive
an MMP requirement. Industrials are evaluated on a case -by -case basis, depending if mercury is a pollutant
of concern. Effluent limits may also be added if annual average effluent concentrations exceed the WQBEL
value (based on the NC WQS of 12 ng/L) and/or if any individual value exceeds a TBEL value of 47 ng/L.
Describe proposed permit actions based on mercury evaluation: A Mercury Minimization Plan (MMP)
special condition was added to the permit in 2014. The MMP was prepared in January 2015 as referenced
Page 7 of 13

in the permit application cover letter. An MMP summary was referenced in the cover letter to the
application, which was requested for review. The summary was prepared for the renewal in August 2018
and includes several actions that were taken to reduce mercury from entering the WWTP.
Submitted low level mercury data from January 2017 through January 2020 were reviewed for TMDL
evaluation. All data were detected with no averages exceeding the TBEL of 47 ng/L and no individual
values exceeding the WQBEL of 28.5 ng/L (Table 2). Because the design flow is > 2 MGD and mercury
was detected in the effluent, an MMP is required. Therefore, the MMP special condition has been reworded
to maintain the MMP.
Table 2. Mercury Effluent Data Summary
2017
2018
---j
11
2020
4 of Samples
4
4
4
1
Annual Average Cone. ng/L
5.7
2.2
3.4
2.8
Maximum Cone., ng/L
7.83
4.32
5.07
2.82
TBEL, ng/L
47
WQBEL, ng/L
28.5
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TNDDLs/Nutrient Management Strategies and their implementation within
this permit: The receiving water is in the High Rock Lake watershed, to which the lake itself is impaired
for Chlorophyll -a. To address this impairment, the permit has a nutrient reopener special condition for any
future TMDL and/or nutrient management strategy. The special condition was modified to include any
future nutrient criteria.
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: NA.
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: A 3-yr compliance schedule with a
WER study option has been added for Total Copper limits to allow for additional data collection and
development and implementation of a compliance strategy.
If applicable, describe any water quality standards variances proposed in accordance with NCGS 143-
215.3(e) and 15A NCAC 2B. 0226 for this permit renewal: NA.
7. Technology -Based Effluent Limitations (TBELs)
Municipals (if not applicable, delete and skip to Industrials)
Are concentration limits in the permit at least as stringent as secondary treatment requirements (30 mg/L
BODs/TSS for Monthly Average, and 45 mg/L for BODs/TSS for Weekly Average). YES.
If NO, provide a justification for alternative limitations (e.g., waste stabilization pond). NA.
Are 85% removal requirements for BOD51TSS included in the permit? YES.
Page 8 of 13

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 (YESINO): NO.
If YES, confirm that antibacksliding provisions are not violated: NA.
10. Monitoring Requirements
Monitoring frequencies for NPDES permitting are established in accordance with the following regulations
and guidance: 1) State Regulation for Surface Water Monitoring, 15A NCAC 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 Professional
Judgement (BPJ). Per US EPA (Interim Guidance, 1996), monitoring requirements are not considered
effluent limitations under Section 402(o) of the Clean Water Act, and therefore anti -backsliding
prohibitions would not be triggered by reductions in monitoring frequencies.
The Permittee requested reduced monitoring frequencies for BOD, TSS and Fecal Coliform on September
11, 2020, during the Public Comment period, demonstrating eligibility criteria were met. Submitted effluent
data for the past three years (August 1, 2017 - July 31, 2020) were evaluated against numerical criteria.
Review of the data showed them to meet the criteria for reduced monitoring frequencies for the three
eligible parameters (Table 3). Therefore, monitoring frequencies has been reduced from daily to 2/week for
BOD, TSS and Fecal Coliform as requested.
Page 9 of 13

Table 3. Monitoring Frequency Reduction (M R) Analysis and Assessment.
Parameter
Three-year Mean
Monthly Average
Percent of Limit
Is Mean < 50% of
Limit
Limit?
BOD
3.0 mg/L
30.0 mg/L
10%
YES
TSS
3.3 mg/L
30.0 mg/L
11%
YES
Fecal Coliform
g cfu/100 mL
200 cfu/100 mL
4%
YES
(geometric mean)
Are > 15 1 sampleo
Parameter
o
200 /o of Monthly
Number of
results > 200 /o of
Are MFR Criteria
Average Limit
Occurrences
Met?
Limit.
BOD
60.0 mg/L
0
NO
YES
TSS
60.0 mg/L
0
NO
YES
Fecal Coliform
400/100 mL
15
NO
YES
(geometric mean)
Fnntnntes
1. Greater than 20 results for Fecal Coliform.
For instream monitoring, refer to Section 4.
11. Electronic Reporting Requirements
The US EPA NPDES Electronic Reporting Rule was finalized on December 21, 2015. Effective December
21, 2016, NPDES regulated facilities are required to submit Discharge Monitoring Reports (DMRs)
electronically. Effective December 21, 2020, NPDES regulated facilities will be required to submit
additional NPDES reports electronically. This permit contains the requirements for electronic reporting,
consistent with Federal requirements.
12. Summary of Proposed Permitting Actions
Table 4. Current Permit Conditions and Proposed Changes.
Parameter
Current Permit'
Proposed Change
Basis for Condition/Change
Flow
MA 7.0 MGD
No change
15A NCAC 213.0505
MA = 30.0 mg/L
No change in limits;
TBEL. Secondary treatment
BOD5
WA = 45.5 mg/L
monitoring reduced
standards/40 CFR 133/15A NCAC 2B
Monitor daily
to 2/week
.0406. Effluent data met criteria for
reduced monitoring frequency.
MA = 30.0 mg/L
No change in limits;
TBEL. Secondary treatment
TSS
WA = 45.0 mg/L
monitoring reduced
standards/40 CFR 133/15A NCAC 2B
Monitor daily
to 2/week
.0406. Effluent data met criteria for
reduced monitoring frequency.
Page 10 of 13

Parameter
Current Permit'
Proposed Change
Basis for Condition/Change
Summer:
Summer:
MA = 2.1 mg/L
WQBEL. Calculation results based on
MA = 13.0 mg/L
WA = 6.3 mg/L
NC's use of EPA criteria in developing
NH3-N
WA = 35.0 mg/L
Winter:
1.0 mg/L summer and 1.8 mg/L winter
Winter:
MA = 6.3 mg/L
values in wasteload allocations to
Monitor only
WA = 18.9 mg/L
protect against NH3-N toxicity (see
Monitor daily
WLA sheet attached).
DO
DA > 5.0 mg/L
Limit year-round
WQBEL. State WQ standard 15A
(summer only)
NCAC 213 .0200.
MA 200 /100 mL
No change in limits;
WQBEL. State WQ standard, 15A
Fecal Coliform
WA 400 /100 mL
monitoring reduced
NCAC 2B .0200. Effluent data met
Monitor daily
to 2/week
criteria for reduced monitoring
frequency.
Total Residual
DM = 28 µg/L
No change
WQBEL. State WQ acute standard,
Chlorine (TRC)
15A NCAC 213 .0200
pH
6 — 9 SU
No change
WQBEL. State WQ standard, 15A
NCAC 213 .0200.
Temperature
Monitor daily
No change
State WQ reporting requirements 15A
NCAC 213 .0500.
Conductivity
Monitor only
No change
State WQ reporting requirements 15A
NCAC 2B .0500.
Total Nitrogen
Monitor monthly
No change
State WQ reporting requirements 15A
(NO3 + NO2 + TKN)
NCAC 213 .0500.
Total Phosphorus
Monitor monthly
No change
State WQ reporting requirements 15A
NCAC 213 .0500.
Remove from
All data nondetect at < 5 mg/L; not
Oil and Grease
Monitor quarterly
required per State WQ reporting
permit
requirements 15A NCAC 213 .0500.
Chronic
dubia
CerToxicity al
WQBEL. No toxics in toxic amounts.
Test
Pass/Fail at 4
Pass/Fail at 42 /0
No change
15A NCAC 2B.0200 and 15A NCAC
effluent
2B.0500.
Hardness -dependent dissolved metals
Add effluent and
water quality standards, approved in
Total Hardness
No requirement
upstream monitoring
2016, need effluent and instream
hardness data for calculations of permit
limitations.
MA = 29.7 µg/L
DM = 35.9µg/L, add
WQBEL. Reasonable potential to
Total Copper
Monitor quarterly
3-yr ComplianceSchedule with WER
exceed allowable discharge
study option.
concentration found.
Monitor monthly.
Page 11 of 13

Parameter
Current Permit'
Proposed Change
Basis for Condition/Change
No reasonable potential to exceed
Total Silver
Monitor quarterly
Remove from
allowable discharge concentration
permit
o
found; max. predicted value < 50 /o of
allowable concentration.
MA = MR µg/L
(DM is lower -only
WQBEL. Reasonable potential to
Monitor & Report
exceed allowable discharge
Total Zinc
Monitor quarterly
for monthly since
concentration found. Monthly average
DM limiting.)
calculated limit was 476 ug/L. See
DM = 447 µg/L
proposed changes.
Monitor monthly.
No reasonable potential to exceed
Chloride
Monitor quarterly
Remove from
allowable discharge concentration
permit
o
found; max. predicted value < 50 /o of
allowable concentration.
Mercury
Revise MMP to
In accordance with 2012 Statewide
Total Mercury
Minimization Plan
require its
Mercury TMDL Implementation, per
(MMP)
maintenance
facility size and monitoring data
criteria.
Effluent Pollutant
Three times per
No change
40 CFR 122
Scan
permit cycle
Electronic Reporting
Electronic Reporting
Update condition to
remove submittal of
In accordance with EPA Electronic
Special Condition
hardcopies
Reporting Rule 2015.
'MGD = Million gallons per day, MA = Monthly Average, WA = Weekly Average, DM = Daily Maximum.
13. Public Notice Schedule:
Permit to Public Notice: 08/14/2020.
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 questions regarding any of the above information or on the attached permit, please contact Gary
Perlmutter at [phone] or via email at gM.perlmutterkncdenr.gov.
Page 12 of 13

15. Fact Sheet Addendum (if applicable):
Were there any changes made since the Draft Permit was public noticed (Yes/No): Only the Permittee
provided comments, most of which were questions for clarity of proposed permit details. Among those
were regarding reduced monitoring frequency for target parameters. A request for reduced monitoring
frequencies for BOD, TSS and Fecal Coliform was received for evaluation.
If Yes, list changes and their basis below:
• Monitoring frequencies for BOD, TSS and Fecal Coliform were reduced from daily to 2/week
based on data evaluation.
• Effluent conductivity monitoring has been reset from daily to weekly for consistency with previous
permits and evaluation of effluent data which shows no impact on instream conductivity.
16. Fact Sheet Attachments (if applicable):
• Pretreatment information request form, completed
• Final 2018 NC 303(d) list, page 238
• Final 2018 NC Integrated Report, pages 1534-1535
• 2008 Yadkin Pee Dee River Basin Plan, page 6
• Effluent summary charts and tables
• BOD and TSS removal calculator output tables
• Instream Monitoring data and charts
• Monitoring Report (MR) Violations page
• WET testing and Self -Monitoring Summary, page 75
• Permit and Pretreatment Compliance Inspection Reports
• NH3/TRC WLA Calculations sheet
• RPA Spreadsheet Summary
• Dissolved Metals Implementation — Freshwater
• Effluent, upstream hardness results
• MMP Summary of Actions
• Mercury WQBEL/TBEL Evaluation data and summary table
• Questions and answers from Permittee
• Letter requesting reduced monitoring frequencies for BOD, TSS and Fecal Coliform
Page 13 of 13

NPDES/A uifer Protection Permitting Unit Pretreatment Information Request Form
PERMIT WRITER COMPLETES THIS PART:
Check all that
PERMIT WRITERS -AFTER you get this form back
apply
from PERCS:
- Notify PERCS if LTMP/STMP data we said should be
on DMRs is not really there, so we can get it for you
(or NOV POTW).
- Notify PERCS if you want us to keep a specific POC
in LTMP/STMP so you will have data for next permit
renewal.
Email PERCS draft permit, fact sheet, RPA.
Send PERCS paper copy of permit (w/o NPDES
boilerplate), cover letter, final fact sheet. Email RPA if
changes.
Date of Request
5/14/2020
municipal renewal
X
Re uestor
Gary Perlmutter
new industries
Facility Name
Mount Airy WWTP
WWTP expansion
Permit Number
NCO021121
Speculative limits
Region
Winston-Salem
stream reclass.
Basin
Yadkin -Pee Dee
outfall relocation
7Q10 change
other
other
check applicable PERCS staff:
Other Comments to PERCS:
Facility is rated 7.0 MGD wtih one SIU listed in its application, submitted in
August 2018..
BIRD, CPF, CTB, FRB, TAR
Vivien Zhong (807-6310)
CHO, HIW, LTN, LUM, NES, NEW, ROA, YAD
x
Monti Hassan (807-6314)
PERCS PRETREATMENT STAFF COMPLETES THIS PART:
Status of Pretreatment Program (check all that apply)
1) facility has no SIU's, does have Division approved Pretreatment Program that is INACTIVE
2) facility has no SIU's, does not have Division approved Pretreatment Program
3) facility has SIUs and DWQ approved Pretreatment Program (list "DEV" if program still under development)
3a) Full Program with LTMP
3b) Modified Program with STMP
4) additional conditions regarding Pretreatment attached or listed below
Flow, MGD
Permitted
Actual
Time period for Actual
STMP time frame:
Industrial
0.065
**0.044
2019
Most recent:
Uncontrollable
n/a
Next Cycle:
a
a
U "
°a
Parameter of
Concern (POC)
Check List
POC due to
NPDES/ Non-
Disch Permit
Limit
Required by
EPA*
Required
by 503
Sludge**
POC due
to SIU***
POTW POC
(Explain
below)****
STMP
Effluent
Freq
LTMP
Effluent
Freq
Q = Quart
BOD
4
Q
TSS
4
Q
NH3
4
Q
M = Monthly
Arsenic
Monitor
4
Q
Cadmium
4
Q
Chromium
4
Q
Copper
4
Q
Cyanide
4
Q
Is all data on DMRs?
Lead
4
Q
YES
Mercury
Monitor
4
Q
NO (attach data)
Molybdenum
4
Q
Nickel
4
Q
Silver
4
Q
Selenium
4
Q
Zinc
4
Q
Is data inspreadsheet?
Total Nitro en
4
Q
YES email to writer
Phosphorus
4
Q
NO
4 Q
4 Q
4 Q
4 Q
*Always in the LTMP/STMP ** Only in LTMP/STMP if sludge land app or composte (dif POCs for incinerators)
*** Only in LTMP/STMP while SIU still discharges to POTW **** Only in LTMP/STMP when pollutant is still of concern to POTW
Comments to Permit Writer (ex., explanation of any POCs; info you have on IU related investigations into NPDES problems):
**Hanesbrands, inc., Textile, closed down in December 2019. MT. Airy has new SIU, Professional Rental Service, comercial laundry facility,
with effective date February 1, 2020, and permitted flow 0.065 MGD.
21121 PERCS request form 2020
Revised: July 24, 2007

2018 NC Category 5 Assessments "303(d) List" Final �.DE
Yadkin -Pee Dee River Basin Subbasin""�"
12-(27.5)a __] YADKIN RIVER (W. Kerr Scott Reservoir below Elevation 1030)
From a point 3.2 mile downstream of Stony Fork to Lewis Fork
Classification WS-IV,B;Tr Length or Area 267 Units FW Acres Previous AU Number 12-(27.5)
Assessment Criteria Status
Reason for Rating
Parameter of Inter
Category
Exceeding Criteria
> 10% and >90 conf
Chlorophyll a (15 jig/I, AL, Tr)
Exceeding Criteria
> 10% and >90 conf
Water Temperature (299C, AL, MT&UP)
5
12-(27.5)b YADKIN RIVER (W. Kerr Scott Reservoir below Elevation 1030)
From Lewis Fork to W. Kerr Scott Dam
Classification WS-IV,B;Tr Length or Area 616 Units FW Acres Previous AU Number 12-(27.5)
Assessment Criteria St"& W&on for Rating
Exceeding Criteria > 10% and >90 conf
Exceeding Criteria > 10% and >90 conf
Exceeding Criteria —1 �10% and >90 conf
Parameter of Interest
WaterTemperature (299C, AL, MT&UP)
Chlorophyll a (15 µg/I, AL, Tr)
pH (9.0, AL, FW)
Category
5
Upper Yadkin Subbasin 03040101
12-72-(4.5)a2 Ararat River
From Seed Cane Creek to Rutledge Creek
Classification C Length or Area 3 Units FW Miles Previous AU Number 12-72-(4.5)a
4ssessment Criteria Status Reasonfnr Rating Parameter of Interest
Exceeding Criteria > 10% and >90 conf Turbidity (50 NTU, AL, FW miles) 0
12-102-13-(2) 1 Cedar Creek
From Davie County SR 1410 to Dutchman Creek
Classification C Length or Area 7 Units FW Miles Previous AU Number
ssessment Criteria Status Reas sting Parameter of Interest Category
Exceeding Criteria Fair Fish Community (Nar, AL, FW)
6/3/2019 2018 NC Category 5 Assessments "303(d) List" Approved by EPA May 22,2019 Page 238 of 262

2018 NC Intergrated Report
12-
Yadkin -Pee Dee River Basin
Ararat River
Upper Yadkin Subbasin
D_E
03040101 SpowAK 21 EiW=mw 13
From a point 0.1 mile upstream of Surry County SR 2080 to Yadkin River
Classification WS-Iv Length or Areal I 2 Units FW Miles Previous AU Number
karameter of Interest
�ategory
Assessment Criteria Status
Collection —Year
Arsenic (10 µg/I, HH, NC)
4t
Exceeding Criteria
2008
Arsenic (50 µg/I, AL, NC)
0
Meeting Criteria
2008
Benthos (Nar, AL, FW)
Meeting Criteria
2001
Cadmium (2 µg/I, AL, FW)
0
Meeting Criteria
2008
Copper (7 µg/I, AL, FW)
Meeting Criteria
2008
Fish Tissue Mercury (Nar, FC, NC)
4t
Exceeding Criteria
2012
Iron (1000 µg/I, Natural, FW)
3z1
Data Inconclusive
2008
Lead (25 µg/I, AL, NC)
0
Meeting Criteria
2008
Zinc (50 µg/I, AL, FW)
Meeting Criteria
2008
12-72-(4.5)a1 Ararat River
From Town of Mount Airy proposed water supply intake to Seed Cane Creek
Classification C Length or Area 5 Units FW Miles Previous AU Number 12-72-(4.5)a
Benthos (Nar, AL, FW)
Dissolved Oxygen (4 mg/I, AL, FW)
Fecal Coliform (GM 200/400, REC, FW)
Fish Tissue Mercury (Nar, FC, NC)
pH (6 su, AL, FW)
pH (9.0, AL, FW)
Turbidity (50 NTU, AL, FW miles)
Water Temperature (299C, AL, MT&UP)
3a
Data Inconclusive 2008
0
Meeting Criteria
0
Meeting Criteria 2016
4t
Exceeding Criteria 2012
Meeting Criteria
0
Fmeeting Criteria
1�
Meeting Criteria
0
Meeting Criteria
6/3/2019 2018 NC Integrated Report Page 1534 of 1747

2018 NC Intergrated Report
12-
Yadkin -Pee Dee River Basin
Lrarat River
E Q,0,
Upper Yadkin Subbasin 03040101 bEhNN—"
From Seed Cane Creek to Rutledge Creek
Classification C Length or Area 3 Units FW Miles Previous AU Number 12-72-(4.5)a
rameter of I
Dissolved Oxygen (4 mg/I, AL, FW)
Fecal Coliform (GM 200/400, REC, FW)
Fish Tissue Mercury (Nar, FC, NC)
pH (6 su, AL, FW)
pH (9.0, AL, FW)
Turbidity (50 NTU, AL, FW miles)
Water Temperature (292C, AL, MT&UP)
Category
Assessment Criteria Status Collection —Year
1�
Meeting Criteria
0
Meeting Criteria 2016
4t
Exceeding Criteria 2012
0
Meeting Criteria
1�
Meeting Criteria
0
Exceeding Criteria
1�
Meeting Criteria
12-72-(4.5)a3 _I lArarat River
From Rutledge Creek to Stoney Creek 12-72-12
Classification C Length or Area 7 Units FW Miles Previous AU Number 12-72-(4.5)a
Parameter of I
Dissolved Oxygen (4 mg/I, AL, FW)
Fecal Coliform (GM 200/400, REC, FW)
Fish Tissue Mercury (Nar, FC, NC)
pH (6 su, AL, FW)
pH (9.0, AL, FW)
Turbidity (50 NTU, AL, FW miles)
Water Temperature (292C, AL, MT&UP)
Assessment Criteria Status Collection —Year
Meeting Criteria
0
Meeting Criteria 2016
4t
Exceeding Criteria 2012
0
Meeting Criteria
Meeting Criteria
3a
Data Inconclusive
Eeeting Criteria
6/3/2019 2018 NC Integrated Report Page 1535 of 1747

Ambient Water Quality
co
O
0
fV
Turbidity
Turbidity violations are common throughout the Yadkin River
Headwaters (Figure 1-5). Turbidity is a measure of cloudiness in
water and is often accompanied with excessive sediment deposits in
the streambed. Excessive sediments deposited on stream and lake
bottoms can choke spawning beds (reducing fish survival and growth
rates), damage fish food sources, fill in pools (reducing cover from
prey and high temperature refuges), and reduce habitat complexity
in stream channels. Excessive suspended sediments can make it
more difficult for fish to find prey and at high levels can cause direct
physical harm, such as clogged gills. Sediments can cause taste and
odor problems, block water supply intakes, foul water treatment
systems, and fill reservoirs. (USEPA, 1999 and Waters, 1995). Sand
and silt were noted in the stream substrate at many of the biological
sample sites in the Yadkin River Headwaters.
FIGURE 1 -5. TURBIDITY VIOLATIONS
Percentage of Turbidity Violation:
Percent
>50 NTU
01.:
❑ yc - 1 it
D 1190 - 1 yo
16% - M-o
22% 2Yo
Soil erosion is the most common source of turbidity and sedimentation and while some erosion is a natural
phenomenon, human land use practices accelerate the process to unhealthy levels. Construction sites, mining
operations, agricultural operations, logging operations, excessive stormwater flow off impervious surfaces are all
potential sources. The distribution of turbidity violations and sample locations make it difficult to isolate a single
source of erosion in the Yadkin River Headwaters. It appears, however, violations are highest in the Yadkin River
mainstem, agricultural areas, and transitional suburban areas. Violations are lowest in the upper watershed where
landuse is predominantly forest. This trend demonstrates the importance of protecting and conserving stream
buffers and natural areas.
It is likely that a combination of human caused land disturbances and natural erosion are causing the majority of
turbidity violations in this watershed, with human causes the leading contributor. To appropriately address turbidity
and sediment problems in the Yadkin River Headwaters, an assessment to determine the contribution of human
accelerated erosion sources relative to natural processes should be undertaken. All reasonable efforts to reduce or
eliminate human sources of erosion should be implemented immediately. These efforts can be organized by developing
watershed restoration plans based on the process outlined in Figure 1-3. Plans are needed for each watershed listed
below.
TABLE 1 -2. STREAMS IMPAIRED OR IMPACTED BY TURBIDITY VIOLATIONS IN YADKIN RIVER HEADWATERS
AU NUMBER
NAME
SUBBASIN
MILES
CLASSIFICATION
IMPAIRED
IMPACTED
SOURCE
12-(80.7)
YADKIN RIVER
03-07-02
9.4
WS-IV
X
Stormwater Runoff
12-(86.7)
YADKIN RIVER
03-07-02
10.0
WS-IV
X
Stormwater Runoff
12-(97.5)
YADKIN RIVER
03-07-04
0.5
WS-IV;CA
X
Stormwater Runoff
12-102-(2)b
Dutchman
03-07-05
7.5
C
X
Impervious Surface,
Creek
Agriculture/Pasture
12-63-(9)
Fisher River
03-07-02
21.2
C
X
Land Clearing, Impervious
Surface, Agriculture/Pasture
12-63-14
Cody Creek
03-07-02
7.0
C
Impervious Surface
12-72-(4.5)a
Ararat River
03-07-03
14.2
C
X
Impervious Surface
12-72-(4.5)b
Ararat River
03-07-03
13.7
C
Impervious Surface
1 2 - 8 4 - 1 -
North Deep
03-07-02
17.3
C
Impervious Surface,
(0.5)
Creek
Agriculture/Pasture
1 2 - 8 4 - 2 -
South Deep
03-07-02
2.8
WS-IV
Impervious Surface,
(5.5)
Creek
Agriculture/Pasture
12-94-(0.5)c
Muddy Creek
03-07-04
4.8
C
X
Stormwater Runoff
Salem Creek
12-94-12-(4)
(Middle Fork
03-07-04
12.0
C
Unknown
Muddy Creek)

Mount Airy WWTP Effluent Monitoring NCO021121
8.0
7.0
6.0
Q 5.0
4.0
3.0
2.0
1.0
0.0
X
Flow
♦ Mo Avg
Limit
oti oti oti oti° oti oti° oti
ti\tih\� \��'°oti �\��ti °\yeti ��ti 4,
y
Biological Oxygen Demand (BOD)
Wk Avg ♦ Mo Avg — WA Limit
50
45
40
35
J 30 ---
bao 25
E 20
15
10 ♦
Ib
Q) oy�O oy� oyI oil; oti° oti° oti° o�y
Total Suspended Solids (TSS)
Wk Avg Mo Avg MA Limit WA Limit
50
45
40
35
J 30 -- --� --
bao 25
E 20
15
10♦
0 • ♦ ••'• 'w�M���.
O,� O,�
�ti\�o�ti �\��ti yo\���ti o\1��ti
Summary
Statistics
N
1461
Avg
1.61
SD
0.84
Min
0.57
Max
11.04
Summary
Statistics
N
1000
Avg
3.43
SD
2.43
Min
2
Max
32.2
Summary
Statistics
N
1000
Avg
4.18
SD
3.28
Min
2.34
Max
61.5
Page 1 of 5 GB Perlmutter 7/31/2020

Mount Airy WWTP Effluent Monitoring NCO021121
20
18
16
14
J 12
Sao 10
E 8
6
4
2
0
\oti� \�y\'O
ti
Dissolved Oxygen (DO)
Effluent Limit
j 40
oti° oti oti oti oti oooti°
Ammonia-N (NH3-N)
Wk Avg Mo Avg WA Limit
100
10
"
J
bu
E
1
0
ti
MA Limit
--
•
r ♦�• OW~ • _•
oti oti oti' oti' oti° otio oti°
Fecal Coliform
Wk Avg
Mo Avg WA Limit — — — MA Limit
1,000
0
100
— — —
•
— — — — — — — — — — — —
•96
•
•% % •
•�•
•
:
10
Wt.'
•
1
oti'
oti° ti
o
oti oti' oti' oti' oti° otiv
Summary Statistics
Summer
N
597
Avg
8.81
SD
1.84
Min
6.5
Max
18.6
Winter
N
403
Avg
10.62
SD
2.12
Min
6.9
Max
18
Summary Statistics
Summer
N
366
Avg
0.26
SD
1.06
Min
0.1
Max
15.2
Winter
N
258
Avg
0.18
SD
0.31
Min
0.1
Max
3.26
Summary Statistics
N 1000
Geomean 8.06
Min 1
Max 2420
Page 2 of 5 GB Perlmutter 7/31/2020

Mount Airy WWTP Effluent Monitoring NC0021121
Total Residual Chlorine (TRC)
Effluent Limit Compliant
60 —
50 —
40
30
20
10
0
O,h OHO OHO O,�
�\o�ti o���\� ��tio\� �o\�,��ti h\� y\� o�ti%9�
pH
Effluent
L. Limit
U. Limit
9.5
9.0
8.5
8.0
D 7.5
7.0
6.5
6.0
— — — — — — — —
— — — — — — — -
5.5
5.0
s,
's, 3N O,,
O;, O,O OHO
Temperature
30.0
25.0
20.0
U
0
15.0
10.0
5.0
Orb
��\�\�otio o\��\�oP
Summary
Statistics
N
1000
Avg
12.30
SD
6.10
Min
0
Max
28
Summary
Statistics
N
1000
Avg
7.13
SD
0.23
Min
6.3
Max
7.7
Summary
Statistics
N
1000
Avg
17.42
SD
4.97
Min
5
Max
27
Page 3 of 5 GB Perlmutter 7/31/2020

Mount Airy WWTP Effluent Monitoring NCO021121
25
20
J 15
W
W
E 10
5
0
oti' oti°
Total Nitrogen (TN)
-- TKN NO2+NO3
TN
OHO O,� OVA � �ti
12.0
10.0
8.0
6.0
E
4.0
2.0
0.0
700
600
Total Phosphorus
oti oti oti' oti' oti° oti° oti°
Conductivity
500
E 'q'JroI r IY
400
0
300
200
100
0
oti'
oti°
oti°
oti
oti
oti' oti'
oti°
otio
(3v
Summary
Statistics
Total..
-
N
597
Avg
8.81
SD
1.84
Min
6.5
Max
18.6
NO2+NO3
N
403
Avg
10.62
SD
2.12
Min
6.9
Max
18
TKN
N
403
Avg
10.62
SD
2.12
Min
6.9
Max
18
Summary
Statistics
N
49
Avg
2.39
SD
1.49
Min
0.2
Max
10.1
Summary
Statistics
N
205
Avg
456
SD
256
Min
208
Max
3940
Page 4 of 5 GB Perlmutter 7/31/2020

Mount Airy WWTP Effluent Monitoring NCO021121
40
35
30
25
J
20
15
10
5
0
6
5
4
J
�W 3
2
1
0
Total Copper
Summary
Statistics
N
16
Avg
14
SD
9
Min
6
Max
36
�, \°ti�\�o�� \ti°\�o�� p\�o�� \tih\�o�° ti\�\�o�o tiobO'
ti 3
Total Zinc
Summary
Statistics
N
16
Avg
110
SD
147
Min
31
Max
520
oti oti, 0 oti' oti° oti° e
Page 5 of 5 GB Perlmutter 7/31/2020

NCO021121
BOD monthly r
Month
RR (%)
April-16
97.98
May-16
96.26
June-16
98.49
July-16
98.47
August-16
98.32
September-16
99.07
October-16
99.54
November-16
99.15
December-16
98.76
January-17
97.71
February-17
98.46
March-17
98.72
April-17
97.81
May-17
97.60
June-17
99.06
July-17
99.33
August-17
99.34
September-17
99.09
October-17
99.37
November-17
98.73
December-17
98.16
January-18
98.34
February-18
97.91
March-18
98.92
April-18
98.52
May-18
98.71
June-18
98.61
July-18
99.01
August-18
98.90
September-18
99.10
Mount Airy WWTP Outfall 0
emoval rate
Month
RR (%)
Month
October-18
99.22
April-16
November-18
98.87
May-16
December-18
97.80
June-16
January-19
98.44
July-16
February-19
98.80
August-16
March-19
99.08
September-
April-19
98.20
October-1
May-19
98.59
November-
June-19
99.14
December-
July-19
99.24
January-1
August-19
98.12
February-1
September-19
98.53
March-17
October-19
98.73
April-17
November-19
98.84
May-17
December-19
98.74
June-17
January-20
99.21
July-17
February-20
98.76
August-17
March-20
99.46
September-
April-20
October-1
May-20
Novem ber-
June-20
December-
July-20
January-1
August-20
February-1
September-20
March-18
October-20
April-18
November-20
May-18
Decem ber-20
June-18
January-21
#N/A
July-18
February-21
#N/A
August-18
March-21
#N/A
September-
1
TSS monthly n
6
16
16
7
7
17
17
8
RR (%)
98.93
97.35
98.60
98.51
97.82
16
97.85
98.78
98.95
97.99
96.32
7
97.74
97.92
96.62
97.74
99.50
99.15
99.16
17
99.28
99.14
97.90
97.79
98.82
8
98.47
99.53
99.25
98.79
99.09
98.47
98.66
18
98.50
5/19/2020
?moval rate
Month
October-18
Novem ber-18
December-18
January-19
February-19
March-19
April-19
May-19
June-19
July-19
August-19
September-19
October-19
Novem ber-19
December-19
January-20
February-20
March-20
April-20
May-20
June-20
July-20
August-20
Septem ber-20
October-20
Novem ber-20
December-20
January-21
February-21
March-21
RR (%)
98.97
97.78
98.96
98.41
98.74
99.35
98.21
99.00
99.05
99.16
98.46
98.76
98.70
97.98
98.72
99.12
98.48
99.54
#N/A
#N/A
#N/A
Summary Statistics
BOD removal rate
n
48
Avg
98.65
SD
0.60
Min
96.26
Max
99.54
TSS removal rate
n
48
Avg
98.54
SD
0.70
Min
96.32
Max
99.54

Pilot Mountain WWTP Instream Monitoring NC0026646
Dissolved oxvaen (DO) (ma/L
Date
Upstream
Dnstream
Effluent
Standard
2016-04-17
9
9.4
5
2016-04-19
9.7
5
2016-05-15
8.1
8.3
5
2016-05-17
8.4
5
2016-05-28
7.7
8.1
5
2016-05-31
8.6
5
2016-06-12
6.7
7.1
5
2016-06-14
8.4
5
20 16-06-27
6.7
6.9
7.9
5
2016-07-17
6.6
6.9
5
2016-07-19
7.8
5
20 16-07-28
6.4
6.6
7.4
5
2016-08-14
6.4
6.7
5
2016-08-16
7
5
2016-08-29
6.6
7.4
7
5
2016-09-18
6.9
7.2
5
2016-09-20
7.4
5
20 16-09-29
6.7
7.1
7.5
5
2016-10-16
7.9
8.2
5
2016-10-18
8.4
5
2016-11-13
9.7
10.1
5
2016-11-15
9.8
5
2016-12-11
10.2
10.6
5
2016-12-13
13.6
5
2017-01-16
10
10.5
5
2017-01-17
10.4
5
2017-02-12
9.1
10
5
2017-02-14
10.5
5
2017-03-26
9.2
9.7
5
2017-03-28
8.4
5
2017-04-23
7
7.2
5
2017-04-25
9.2
5
2017-05-07
7
7.5
5
2017-05-08
9.5
5
2017-05-22
6.8
7.1
8.2
5
2017-06-18
6.7
7
5
2017-06-20
7.8
5
20 17-06-29
6.8
7.2
8.6
5
2017-07-16
6.6
6.8
5
2017-07-18
7.3
5
20 17-07-27
6.3
6.5
9.3
5
2017-08-13
6.8
7.1
5
2017-08-15
8.6
5
20 17-08-24
6.3
6.6
7.2
5
2017-09-17
6.7
7.1
5
2017-09-19
8.1
5
2017-09-28
6.5
7.1
8.2
5
2017-10-15
6.8
7.3
5
Page 1of 3 GB Perlmutter 7/31/2020

Pilot Mountain WWTP Instream Monitoring NC0026646
Dissolved oxvaen (DO) (ma/L
Date
Upstream
Dnstream
Effluent
Standard
2017-10-17
8.9
5
2017-11-12
8.8
10
5
2017-11-14
9
5
2017-12-10
10.2
11
5
2017-12-12
9
5
2018-01-21
9.1
9.8
5
2018-01-22
9.4
5
2018-02-18
9.5
10.1
5
2018-02-20
10.5
5
2018-03-18
9.3
9.9
5
2018-03-20
8.9
5
2018-04-08
9.2
9.6
5
2018-04-10
8.7
5
2018-05-13
6.8
7.3
5
2018-05-15
11.4
5
2018-05-30
6.6
7.1
12.3
5
2018-06-17
6.8
7.1
5
2018-06-19
13
5
20 18-06-28
6.4
7.1
18.6
5
2018-07-15
6.6
7.1
5
2018-07-17
7.3
5
2018-07-26
6.5
7.2
11.5
5
2018-08-10
8.2
7.7
8.8
5
2018-08-26
6.6
7.2
5
2018-08-28
8.3
5
20 18-09-19
8.8
8.3
7.7
5
2018-09-29
8.7
8.3
5
2018-10-02
9.1
5
2018-10-16
9.2
9.3
8
5
2018-11-06
10.1
10.1
9.7
5
2018-12-04
11.6
11.7
9
5
2019-01-08
10.2
10.3
9.6
5
2019-02-05
10.4
10.5
9.2
5
2019-03-05
11.8
11.5
15.5
5
2019-04-09
10.3
10.6
8.2
5
2019-05-01
9.4
9.5
9.1
5
2019-05-21
9.6
9.3
7.8
5
2019-06-03
9.8
9.4
10.7
5
20 19-06-18
8.3
8.7
13.3
5
2019-07-09
8.4
8.2
7.1
5
2019-07-22
8.5
7.6
7.5
5
2019-08-06
8.4
8
7.4
5
2019-08-20
8.8
8.4
7.2
5
20 19-09-04
8.3
8.1
8.4
5
2019-09-24
9.2
9.1
8.4
5
2019-10-15
10.7
10.2
8.3
5
2019-11-12
9.2
9.3
10.9
5
2019-12-10
10.7
11
10.8
5
Page 2of 3 GB Perlmutter 7/31/2020

Pilot Mountain WWTP Instream Monitoring NCO026646
Dissolved oxygen (DO) (mg/L)
Date Upstream Dnstream Effluent Standard
N
65
65
65
Avg
8.2
8.5
9.2
SD
1.5
1.5
2.1
Min
6.3
6.5
7
Max
11.8
11.7
18.6
t-Test: Paired Two Sample for Means
Upstream
Dnstream
Mean
8.233846
8.475385
Variance
2.358524
2.160322
Observations
65
65
Pearson Correlation
0.967191
Hypothesized Mean Difference
0
df
64
t Stat
-4.98719
P(T<=t) one -tail
2.48E-06
t Critical one -tail
1.669013
P(T<=t) two -tail
4.96E-06
t Critical two -tail
1.99773
Dissolved Oxygen (DO)
0 Upstream Dnstream Effluent Standard
20.0
18.0
16.0
14.0
12.0 n I�
Sao 10.0 Vn r ,,.� Allow
8.0 6.0 �� ■r��� ����
- ■��
4.0
2.0
0.0
ti� ti1 tit tit
O� O� Off` ON
Page 3of 3 GB Perlmutter 7/31/2020

Pilot Mountain WWTP Instream Monitoring
NCO026646
Temperature,
water (_)
Date
Upstream
Dnstream
D-U diff.
Effluent
Standard
4/17/2016
14.3
13.7
-0.6
29
4/18/2016
15
29
5/15/2016
16.6
15.6
-1
29
5/16/2016
17
29
5/27/2016
21
29
5/28/2016
21.7
20.2
-1.5
29
6/12/2016
23.4
22
-1.4
29
6/13/2016
19
29
6/27/2016
24.6
23.8
-0.8
23
29
7/17/2016
26.2
25.7
-0.5
29
7/18/2016
25
29
7/28/2016
27.6
25.3
-2.3
26
29
8/14/2016
27.1
26.1
-1
29
8/15/2016
26
29
8/29/2016
25.1
24.1
-1
25
29
9/18/2016
25.2
23.4
-1.8
29
9/19/2016
23
29
9/29/2016
24.2
23.4
-0.8
23
29
10/16/2016
16.9
15.8
-1.1
29
10/17/2016
19
29
11 /13/2016
11.2
10.7
-0.5
29
11 /14/2016
13
29
12/11 /2016
7.4
6.8
-0.6
29
12/12/2016
11
29
1/16/2017
8.3
7.1
-1.2
29
1 /17/2017
15
29
2/12/2017
10.6
9.8
-0.8
29
2/13/2017
12
29
3/26/2017
13.2
12.2
-1
29
3/27/2017
16
29
4/23/2017
16.2
15.3
-0.9
29
4/24/2017
15
29
5/7/2017
17.3
16.2
-1.1
29
5/8/2017
17
29
5/22/2017
21.2
20.3
-0.9
21
29
6/18/2017
26.4
24.6
-1.8
29
6/19/2017
23
29
6/29/2017
23.1
22.1
-1
21
29
7/16/2017
26.5
26
-0.5
29
7/17/2017
22
29
7/27/2017
27.2
26
-1.2
24
29
8/13/2017
25.7
25
-0.7
29
8/14/2017
23
29
8/24/2017
26.2
25.6
-0.6
24
29
9/17/2017
21.1
19.6
-1.5
29
9/18/2017
21
29
9/28/2017
24.9
23.6
-1.3
22
29
10/15/2017
23.8
22
-1.8
29
10/16/2017
17
29
11 /12/2017
10.2
9.6
-0.6
29
11 /13/2017
14
29
12/10/2017
7.2
6.1
-1.1
29
12/11 /2017
9
29

Pilot Mountain WWTP Instream Monitoring
NCO026646
Temperature,
water (_)
Date
Upstream
Dnstream
D-U diff.
Effluent
Standard
1 /21 /2018
9.4
8.6
-0.8
29
1 /22/2018
10
29
2/18/2018
12.5
11.9
-0.6
29
2/19/2018
13
29
3/18/2018
11.2
10.4
-0.8
29
3/19/2018
14
29
4/8/2018
11.1
10.6
-0.5
29
4/9/2018
13
29
5/13/2018
19.1
18.9
-0.2
29
5/14/2018
20
29
5/30/2018
25.3
23.6
-1.7
22
29
6/17/2018
26.2
24.3
-1.9
29
6/18/2018
24
29
6/28/2018
27.2
25.6
-1.6
23
29
7/15/2018
26.3
25.4
-0.9
29
7/16/2018
24
29
7/26/2018
26.1
24.9
-1.2
24
29
8/10/2018
23.6
24.8
1.2
24
29
8/26/2018
26
24.5
-1.5
29
8/27/2018
23
29
9/19/2018
21.6
22.3
0.7
23
29
9/28/2018
23
29
9/29/2018
21.2
21.4
0.2
29
10/16/2018
17.9
18.2
0.3
20
29
11 /6/2018
14
14
0
18
29
12/4/2018
8.1
8.4
0.3
14
29
1 /8/2019
8.9
9
0.1
14
29
2/5/2019
8.6
8.5
-0.1
12
29
3/5/2019
6.1
7
0.9
10
29
4/9/2019
16.3
16.7
0.4
17
29
5/1 /2019
18.5
19.1
0.6
20
29
5/21 /2019
19.2
20.5
1.3
21
29
6/3/2019
20.2
21.4
1.2
13
29
6/18/2019
20.4
20.6
0.2
22
29
7/9/2019
23
24.4
1.4
23
29
7/22/2019
23.5
25
1.5
24
29
8/6/2019
21.1
22.4
1.3
23
29
8/20/2019
24.4
25.3
0.9
23
29
9/4/2019
21.5
22.4
0.9
23
29
9/24/2019
21.5
22.2
0.7
20
29
10/15/2019
14.7
15.5
0.8
19
29
11 /12/2019
8.7
8.9
0.2
14
29
12/10/2019
7.6
7.3
-0.3
13
29
N
65
65
65
65
Avg
18.9
18.5
-0.5
19.2
S D
6.7
6.5
1.0
4.7
Min
6.1
6.1
-2.3
9
Max
27.6
26.1
1.5
26

Pilot Mountain WWTP Instream Monitoring NCO026646
Temperature, water (_ Q
Date Upstream Dnstream D-U diff. Effluent Standard
t-Test: Paired Two Sample for Means
Upstream
Dnstream
Mean
18.94769
18.48769
Variance
44.62378
42.70297
Observations
65
65
Pearson Correlation
0.989848
Hypothesized Mean Difference
0
df
64
t Stat
3.893195
P(T<=t) one -tail
0.000119
t Critical one -tail
1.669013
P(T<=t) two -tail
0.000239
t Critical two -tail
1.99773
Temperature
Upstream Dnstream Effluent Standard
35
30
25 r
v 20
o 15 !■■
10 ■ , ■ ■■■ ■
5
0
1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Cry � �Z � 1 y 4 4�y C'
O� O� O� Off' Off' Off' Off' O� Off' Off' Off' Off' Off' Off' Off'
ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti

Pilot Mountain WWTP
Instream Monitoring NCO026646
Specific conductance
( S/cm
Date
Upstream
Dnstream Effluent
4/17/2016
128
94
4/18/2016
433
5/15/2016
143
98
5/16/2016
426
5/28/2016
114
94
6/1 /2016
491
6/12/2016
140
102
6/13/2016
480
6/27/2016
153
110
446
7/12/2016
425
7/17/2016
138
114
7/28/2016
122
90
8/14/2016
138
102
8/15/2016
437
8/29/2016
155
104
448
9/18/2016
158
104
9/19/2016
481
9/29/2016
156
107
10/4/2016
416
10/16/2016
137
103
10/17/2016
516
11 /13/2016
139
104
11 /14/2016
433
12/11 /2016
134
109
12/12/2016
424
1 /16/2017
132
96
1 /17/2017
464
2/12/2017
156
103
2/13/2017
518
3/26/2017
153
117
3/27/2017
433
4/23/2017
140
90
4/24/2017
380
5/7/2017
137
96
5/8/2017
337
5/22/2017
138
104
394 3940
6/18/2017
139
102
6/19/2017
379
6/29/2017
153
103
7/3/2017
408
7/16/2017
147
109
7/17/2017
469
7/27/2017
162
109
8/1 /2017
450
8/13/2017
153
104
8/14/2017
424
8/24/2017
162
110
8/28/2017
426
9/17/2017
145
104
9/18/2017
433
9/28/2017
136
102
10/2/2017
461
10/15/2017
136
103
Page 1 of 3 GB Perlmutter 7/31/2020

Pilot Mountain WWTP
Instream Monitoring NCO026646
Specific conductance
( S/cm
Date
Upstream
Dnstream Effluent
10/16/2017
453
11 /12/2017
147
90
11 /13/2017
429
12/10/2017
126
95
12/11 /2017
437
1 /21 /2018
132
103
1 /22/2018
482
2/18/2018
138
96
2/19/2018
456
3/18/2018
143
106
3/19/2018
496
4/8/2018
135
94
4/10/2018
467
5/13/2018
128
108
5/14/2018
505
5/29/2018
420
5/30/2018
162
119
6/17/2018
138
101
6/18/2018
509
6/28/2018
165
117
7/15/2018
146
109
7/16/2018
493
7/23/2018
552
7/26/2018
149
107
8/10/2018
70
76
8/13/2018
437
8/26/2018
137
104
8/27/2018
470
9/17/2018
275
9/19/2018
60
64
9/29/2018
62
65
10/2/2018
463
10/15/2018
378
10/16/2018
62
81
11 /5/2018
410
11 /6/2018
61
66
12/3/2018
371
12/4/2018
56
68
1 /8/2019
54
65
312
2/4/2019
410
2/5/2019
52
50
3/4/2019
323
3/5/2019
50
62
4/8/2019
472
4/9/2019
52
55
5/1 /2019
50
55
567
5/20/2019
481
5/21 /2019
53
65
6/3/2019
53
55
488
6/17/2019
539
6/18/2019
52
57
7/9/2019
59
67
544
7/22/2019
58
88
543
Page 2 of 3 GB Perlmutter 7/31/2020

Pilot Mountain WWTP Instream Monitoring NCO026646
Specific conductance ( S/cm
Date
Upstream
Dnstream Effluent
8/5/2019
403
8/6/2019
61
75
8/19/2019
478
8/20/2019
60
74
9/3/2019
469
9/4/2019
59
70
9/23/2019
573
9/24/2019
60
81
10/14/2019
523
10/15/2019
58
50
11 /12/2019
61
50
466
12/9/2019
532
12/10/2019
56
66
N
65
65
63
Avg
112.4
89.9
451.7
SD
42.2
20.1
60.1
Min
50
50
275
Max
165
119
573
t-Test: Paired Two Sample for Means
Upstream
Dnstream
Mean
112.4462
89.86154
Variance
1783.063
402.2149
Observations
65
65
Pearson Correlation
0.933115
Hypothesized Mean Difference
0
df
64
t Stat
7.403703
P(T<=t) one -tail
1.81 E-10
t Critical one -tail
1.669013
P(T<=t) two -tail
3.63E-10
t Critical two -tail
1.99773
Up- and dnstream sites combined
Before 912018
Since 912018
86
44
121.8
60.9
23.0
8.9
70
50
165
88
Specific Conductance
♦ Upstream Effluent Dnstream
700
600
500
E 400
300
200
100 14AA0"i*AA, AA A1WA��AA AAA& f:LA
tit tit 11
Off` Off` Off` Off`
Page 3 of 3 GB Perlmutter 7/31/2020

Pilot Mountain WWTP
Instream Monitoring NCO026646
Fecal coliform Wu/100 mL)
Date Upstream Dnstream
Effluent
4/17/2016 82
60
4/19/2016
3
5/15/2016 110
62
5/18/2016
5
6/12/2016 104
60
6/14/2016
3
7/17/2016 210
70
7/19/2016
4
8/14/2016 154
84
8/16/2016
23
9/18/2016 131
80
9/20/2016
5
10/16/2016 154
64
10/18/2016
3
11 /13/2016 100
62
11/15/2016
16
12/11 /2016 114
64
12/13/2016
8
1 /16/2017 88
64
1 /17/2017
6
2/12/2017 108
72
2/14/2017
17
3/26/2017 106
86
3/28/2017
36
4/23/2017 200
114
4/25/2017
ill
5/7/2017 82
54
5/9/2017
36
6/18/2017 114
56
6/19/2017
4
7/16/2017 100
62
7/18/2017
3
8/13/2017 108
62
8/15/2017
10
9/17/2017 84
64
9/19/2017
8
10/15/2017 86
52
10/17/2017
3
11 /12/2017 86
46
11 /14/2017
4
12/10/2017 98
60
12/12/2017
6
1 /21 /2018 94
60
1 /23/2018
3
2/18/2018 82
58
2/20/2018
4
3/18/2018 86
58
3/20/2018
3
4/8/2018 82
60
4/10/2018
2
5/13/2018 88
58
5/15/2018
29
6/17/2018 86
62
Page 1 of 2 GB Perlmutter 7/31/2020

Pilot Mountain WWTP Instream Monitoring NCO026646
Fecai coiiform Wu/100 mL)
Date
Upstream Dnstream
Effluent
6/19/2018
13
7/15/2018
94
62
7/17/2018
27
8/26/2018
94
70
8/28/2018
3
9/19/2018
520
510
6
10/16/2018
560
550
40
11 /6/2018
9800
6000
8
12/4/2018
791
580
1
1 /8/2019
136
58
10
2/5/2019
56
58
1
3/5/2019
66
64
4
4/9/2019
270
144
4
5/21 /2019
440
360
5
6/18/2019
6000
9200
145
7/9/2019
764
400
4
8/20/2019
430
80
12
9/24/2019
86
96
23
10/15/2019
110
64
25
11 /12/2019
655
159
10
12/10/2019
5700
510
5
N
45
45
45
Geomean
180
108
8
Min
56
46
1
Max
9800
9200
145
Fecal Coliform
Upstream Effluent Dnstream
10,000 ! t .
J 1,000 N • A
E A♦ �♦ •
100 . A= 96 !�= N •AAA AAA- A AA ■ A • ■ • �•
10 ■ ■■ ■ ■
■■ ■ ■■ ■ ■■ ■■■ 00
1111111111111 NONE
■
1
tit ti� ti1 ti�
Off` Off` Off` Off`
LOBO LO,� TLO06 LO,�
Page 2 of 2 GB Perlmutter 7/31/2020

MONITORING REPORT(MR) VIOLATIONS for:
Permit: NCO021121 MRS Betweel 4 - 2015 and 5 - 2020 Region: %
Facility Name:% Param Name% County: %
Major Minor: %
Report Date: 05/22/2C Page 1 of 1
Violation Category:Limit Violation Program Category: NPDES VVW
Subbasin:% Violation Action:
PERMIT: NCO021121 FACILITY: City of Mount Airy -Mount Airy WWTP COUNTY: Surry REGION: Winston-Salem
Limit Violation
MONITORING VIOLATION UNIT OF CALCULATED %
REPORT OUTFALL LOCATION PARAMETER DATE FREQUENCY MEASURE LIMIT VALUE Over VIOLATION TYPE VIOLATION ACTION
07-2015 001 Effluent Coliform, Fecal MF, MFC 07/11/15 5 X week #/100ml 400 426.44 6.6 Weekly Geometric Mean Proceed to NOD
Broth, 44.5 C Exceeded

Whole Effluent Toxicity Testing and Self Monitoring Summary
Motiva Enterprises -Paw Creek
NCO022187/001 County:
Mecklenburg
Region:
MRO
Basin:
CTB34
Jan Apr Jul Oct
Ceri24PF
Begin:
9/1/2015
Cerio 24 PF Lim @ 90
Non Comp:
70,10:
0.0
PF: NA
IWC:
100
Freq: Q
J
F M
A
M
J
J
A
5
O
2016
Pass
- -
Pass
-
-
Pass
-
-
Pass
2017
Pass
- -
Pass
-
-
Pass
-
-
Pass
2015
Pass
- -
Pass
-
-
Pass
-
-
Pass
2019
Pass
- -
Pass
-
-
Pass
-
-
Pass
2020
Pass
- -
-
-
-
-
-
-
-
Mt. Airy WWTP
NCO021121/001 County:
Surry
Region:
WSRO
Basin:
YAD03
Jan Apr Jul Oct
Ceri7dPF
Begin:
9/1/2014
chr lim: 42%
Non Comp:
Single
70,10:
14.9
PF: 7.0
IWC:
42.0 Freq: Q
J
F M
A
M
J
J
A
5
O
2016
Pass
- -
Pass
-
-
Pass
-
- Pass
>S,
2017
Pass >84(P)
- -
Pass
-
-
Pass
-
-
Pass
2015
Pass
- - Pass
>84(P)
-
-
Pass
-
-
Pass
2019
Pass
- -
Pass
-
-
Pass
-
-
Pass
2020
Pass
- -
-
-
-
-
-
-
-
Mt. Gilead WWTP
NCO021105/001 County:
Montgomery
Region:
FRO
Basin:
YAD10
Mar Jun Sep Dec
Ceri7dPF
Begin:
3/1/2005
chr lim: 3.2%
Non Comp:
Single
70,10:
40
PF: 0.85
IWC:
3.2
Freq: Q
J
F M
A
M
J
J
A
5
O
2016
-
- Pass
-
-
Pass
-
-
Pass
-
2017
-
- Pass
-
-
Pass
-
-
Pass
-
2015
-
- Pass
-
-
Pass
-
-
Pass
-
2019
-
- Pass
-
-
Pass
-
-
Pass
-
Mt. Holly WWTP
NCO021156/001 County:
Gaston
Region:
MRO
Basin:
CTB33
Feb May Aug Nov
Ceri7dPF
Begin:
1/1/2007
chr lim: 6%
Non Comp:
Single
70,10:
95.0
PF: 4.0
IWC:
6.0
Freq: Q
J
F M
A
M
J
J
A
5
O
2016
-
Pass -
-
Pass
-
-
Pass
-
-
2017
-
Pass -
-
Pass
-
-
Pass >12(P)
-
-
2015
-
Pass >12(P) -
-
Pass
-
-
Pass
-
-
2019
-
Pass >12(P) -
-
Pass
-
-
Pass
-
-
2020
-
Pass -
-
-
-
-
-
-
-
Mt. Olive Pickle Co,
Inc. WWTP
NC0001074/001 County:
Wayne
Region:
WARO
Basin:
CPF21
Jan Apr Jul Oct
Cer7dChV
Begin:
8/1/2011
P-2 chr monit (100,75
Non Comp:
70,10:
0.0
PF: 0.40
IWC:
100
Freq: Q
J
F M
A
M
J
J
A
5
O
2016
35.4
- -
35.4
-
-
35.4
-
-
35.4
2017
35.4
- -
17.7
-
-
17.7
-
-
35.4
2015
35.4
- -
17.7
-
-
17.7
-
-
35.4
2019
17.7
- -
35.4
-
-
35.4
-
-
35.4
2020
17.7
- -
-
-
-
-
-
-
-
SOC JOC:
N
SOC JOC:
N
SOC JOC:
N
SOC JOC:
N
Pass >12(P)
Pass
Pass
Pass
SOC JOC:
N
0
0
D
Pass
Pass
Pass
Pass
0
0
Legend: P= Fathead minnow (Pimphales promelas), H=No Flow (facility is active), s = Split test between Certified Labs Page 76 of 120

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 15 I 3 I NC0021121 I11 121 18/11/28 I17 18 n 19 L G j 201
211111111111III11IIIIIII111111III IIIIIIIIIII f6
Inspection
Work Days Facility Self -Monitoring Evaluation Rating B1 CA ---------------------- Reserved -------------------
67
I 71 I I 72 L n, � 73 LLI74 71 I I I I I I I80
70 Iu ty LJ
Section B: Facility Data
Name and Location of Facility Inspected (For Industrial Users discharging to POTW, also include
Entry Time/Date
Permit Effective Date
POTW name and NPDES permit Number)
09:OOAM 18/11/28
14/09/01
Mount Airy WWTP
US Hwy 52 S
Exit Time/Date
Permit Expiration Date
Mount Airy NC 27030
11:OOAM 18/11/28
19/02/28
Name(s) of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s)
Other Facility Data
Christopher S Marion/ORC/336-786-3597/
Name, Address of Responsible Official/Title/Phone and Fax Number
Contacted
Barbara Jones,300 S Main St Mount Airy NC 27030/City
Manager/336-786-3501/3367197506 No
Section C: Areas Evaluated During Inspection (Check only those areas evaluated)
Permit 0 Flow Measurement Operations & Maintenar Records/Reports
Self -Monitoring Progran 0 Sludge Handling Dispos 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
Gary Hudson DWR/Division of Water Quality/336-776-9694/
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
31 NCO021121 I11 121 18/11/28 117 18IC
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
Page#

Permit: NCO021121 Owner -Facility: Mount Airy WWTP
Inspection Date: 11/28/2018 Inspection Type: Compliance Evaluation
Permit
Yes
No
NA
NE
(If the present permit expires in 6 months or less). Has the permittee submitted a new
0
❑
❑
❑
application?
Is the facility as described in the permit?
0
❑
❑
❑
# Are there any special conditions for the permit?
❑
0
❑
❑
Is access to the plant site restricted to the general public?
0
❑
❑
❑
Is the inspector granted access to all areas for inspection?
0
❑
❑
❑
Comment: .
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: .
Bar Screens
Yes
No
NA
NE
Type of bar screen
a.Manual
❑
b.Mechanical
Are the bars adequately screening debris?
0
❑
❑
❑
Is the screen free of excessive debris?
0
❑
❑
❑
Is disposal of screening in compliance?
0
❑
❑
❑
Is the unit in good condition?
❑
❑
❑
Comment: .
Grit Removal
Yes
No
NA
NE
Type of grit removal
a.Manual
❑
b.Mechanical
Is the grit free of excessive organic matter?
0
❑
❑
❑
Is the grit free of excessive odor?
0
❑
❑
❑
# Is disposal of grit in compliance?
0
❑
❑
❑
Comment: .
Page# 3

Permit: NC0021121 Owner -Facility:
Inspection Date: 11/28/2018 Inspection Type:
Mount Airy WWTP
Compliance Evaluation
Flow Measurement - Influent
Yes
No
NA
NE
# Is flow meter used for reporting?
0
❑
❑
❑
Is flow meter calibrated annually?
0
❑
❑
❑
Is the flow meter operational?
0
❑
❑
❑
(If units are separated) Does the chart recorder match the flow meter?
❑
❑
❑
Comment: .
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?
0
❑
❑
❑
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?
❑
❑
❑
Is the sludge blanket level acceptable? (Approximately'/4 of the sidewall depth)
❑
❑
❑
Comment: .
Trickling Filter
Yes
No
NA
NE
Is the filter free of ponding?
0
❑
❑
❑
Is the filter free of leaks at the center column of filter's distribution arms?
0
❑
❑
❑
Is the distribution of flow even from the distribution arms?
❑
0
❑
❑
Is the filter free of uneven or discolored growth?
❑
0
❑
❑
Is the filter free of sloughing of excessive growth?
0
❑
❑
❑
Are the filter's distribution arms orifices free of clogging?
0
❑
❑
❑
Is the filter free of excessive filter flies, worms or snails?
0
❑
❑
❑
Comment: .
Aeration Basins Yes No NA NE
Mode of operation Ext. Air
Type of aeration system Surface
Is the basin free of dead spots? 0 ❑ ❑ ❑
Page# 4

Permit: NCO021121 Owner -Facility:
Inspection Date: 11/28/2018 Inspection Type:
Mount Airy WWTP
Compliance Evaluation
Aeration Basins
Yes
No
NA
NE
Are surface aerators and mixers operational?
0
❑
❑
❑
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?
❑
❑
❑
Is the DO level acceptable?(1.0 to 3.0 mg/I)
❑
❑
❑
Comment: .
Secondary Clarifier
Yes
No
NA
NE
Is the clarifier free of black and odorous wastewater?
0
❑
❑
❑
Is the site free of excessive buildup of solids in center well of circular clarifier?
0
❑
❑
❑
Are weirs level?
0
❑
❑
❑
Is the site free of weir blockage?
0
❑
❑
❑
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 return rate acceptable (low turbulence)?
0
❑
❑
❑
Is the overflow clear of excessive solids/pin floc?
0
❑
❑
❑
Is the sludge blanket level acceptable? (Approximately'/4 of the sidewall depth)
❑
❑
❑
Comment: .
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?
0
❑
❑
❑
Comment: .
De -chlorination Yes No NA NE
Type of system ? Liquid
Page# 5

Permit: NCO021121 Owner -Facility:
Inspection Date: 11/28/2018 Inspection Type:
Mount Airy WWTP
Compliance Evaluation
De -chlorination
Yes
No
NA
NE
Is the feed ratio proportional to chlorine amount (1 to 1)?
0
❑
❑
❑
Is storage appropriate for cylinders?
❑
❑
0
❑
# Is de -chlorination substance stored away from chlorine containers?
0
❑
❑
❑
Comment: .
Are the tablets the proper size and type? ❑ ❑ 0 ❑
Are tablet de -chlorinators operational? ❑ ❑ 0 ❑
Number of tubes in use?
Comment: .
Flow Measurement - Effluent
Yes
No
NA
NE
# Is flow meter used for reporting?
❑
0
❑
❑
Is flow meter calibrated annually?
0
❑
❑
❑
Is the flow meter operational?
0
❑
❑
❑
(If units are separated) Does the chart recorder match the flow meter?
❑
❑
❑
Comment: .
Effluent Sampling
Yes
No
NA
NE
Is composite sampling flow proportional?
0
❑
❑
❑
Is sample collected below all treatment units?
0
❑
❑
❑
Is proper volume collected?
0
❑
❑
❑
Is the tubing clean?
0
❑
❑
❑
# Is proper temperature set for sample storage (kept at less than or equal to 6.0 degrees
0
❑
❑
❑
Celsius)?
Is the facility sampling performed as required by the permit (frequency, sampling type
0
❑
❑
❑
representative)?
Comment: .
Solids Handling Equipment
Yes
No
NA
NE
Is the equipment operational?
0
❑
❑
❑
Is the chemical feed equipment operational?
0
❑
❑
❑
Is storage adequate?
0
❑
❑
❑
Is the site free of high level of solids in filtrate from filter presses or vacuum filters?
0
❑
❑
❑
Is the site free of sludge buildup on belts and/or rollers of filter press?
0
❑
❑
❑
Is the site free of excessive moisture in belt filter press sludge cake?
0
❑
❑
❑
Page# 6

Permit: NC0021121
Inspection Date: 11/28/2018
Solids Handling Equipment
The facility has an approved sludge management plan?
Comment: .
Owner -Facility: Mount Airy WWTP
Inspection Type: Compliance Evaluation
Yes No NA NE
■ ❑ ❑ ❑
Page#

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 15 I 3 I NCO021121 I11 121 19/06/04 I17 18 n 19 L G j 201
211111111111III11IIIIIII111111III IIIIIIIIIII f6
Inspection
Work Days Facility Self -Monitoring Evaluation Rating B1 CA ---------------------- Reserved -------------------
67
70 �s LJ � 71 I tyI 72 L Ln, � 73LLI74 71
J 1 1 1 1 L L j80
Section B: Facility Data
Name and Location of Facility Inspected (For Industrial Users discharging to POTW, also include
Entry Time/Date
Permit Effective Date
POTW name and NPDES permit Number)
10:15AM 19/06/04
14/09/01
Mount Airy WWTP
US Hwy 52 S
Exit Time/Date
Permit Expiration Date
Mount Airy NC 27030
12:25PM 19/06/04
19/02/28
Name(s) of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s)
Other Facility Data
Christopher S Marion/ORC/336-786-3597/
Name, Address of Responsible Official/Title/Phone and Fax Number
Contacted
Barbara Jones,300 S Main St Mount Airy NC 27030/City
Manager/336-786-3501/3367197506 No
Section C: Areas Evaluated During Inspection (Check only those areas evaluated)
Other
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
Jim J Gonsiewski DWR/Division of Water Qua lity/336-776-9704/
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
31 NCO021121 I11 121 19/06/04 117 18 I p
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
Page#

Permit: NCO021121
Inspection Date: 06/04/2019
Other
Comment:
Owner -Facility: Mount Airy WWTP
Inspection Type: Pretreatment Compliance
Yes No NA NE
Page#

NH3/TRC WLA Calculations
Mount Airy WWTP
Permit No. NC0021121
Prepared By: Gary Perlmutter
Enter Design Flow (MGD): 7
Enter s7Q10 (cfs): 14.9
Enter w7Q10 (cfs): 31
Total Residual Chlorine (TRC)
Daily Maximum Limit (ug/1)
Ammonia (Summer)
Monthly Average Limit (mg NH3-N/1)
s7Q10 (CFS)
14.9
s7Q10 (CFS)
14.9
DESIGN FLOW (MGD)
7
DESIGN FLOW (MGD)
7
DESIGN FLOW (CFS)
10.85
DESIGN FLOW (CFS)
10.85
STREAM STD (UG/L)
17.0
STREAM STD (MG/L)
1.0
Upstream Bkgd (ug/1)
0
Upstream Bkgd (mg/1)
0.22
IWC (%)
42.14
IWC (%)
42.14
Allowable Conc. (ug/1)
40
Allowable Conc. (mg/1)
2.1
Ammonia (Winter)
Monthly Average Limit (mg NH3-N/1)
Fecal Coliform
w7Q10 (CFS)
31
Monthly Average Limit:
2001100- DESIGN FLOW (MGD)
7
(If DF >331; Monitor)
DESIGN FLOW (CFS)
10.85
(If DF<331; Limit)
STREAM STD (MG/L)
1.8
Dilution Factor (DF)
2.37 Upstream Bkgd (mg/1)
0.22
IWC (%)
25.93
Allowable Conc. (mg/1)
6.3
Total Residual Chlorine
1. Cap Daily Max limit at 28 ug/I to protect for acute toxicity
Ammonia (as NH3-N)
1. If Allowable Conc > 35 mg/l, Monitor Only
2. Monthly Avg limit x 3 = Weekly Avg limit (Municipals); capped at 35 mg/I
3. Monthly Avg limit x 5 = Daily Max limit (Non-Munis); capped at 35 mg/I
Far-ni ('nlifnrm
1. Monthly Avg limit x 2 = 400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non -Muni)

Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM DATA POINTS = 58
REQUIRED DATA ENTRY
Table 1. Proiect Information
❑ CHECK IF HQW OR ORW WQS
Facility Name
Mount Airy WWTP
WWTP/WTP Class
IV
NPDES Permit
NCO021121
Outfall
001
Flow, Qw (MGD)
7.000
Receiving Stream
Aratat River
HUC Number
03040101
Stream Class
❑ Apply WS Hardness WQC
C
7Q10s (cfs)
14.90
31.00
7Q10w (cfs)
30Q2 (cfs)
QA (cfs)
12.33
1Q10s (cfs)
Effluent Hardness
I 76.38 ni (Avg)
Upstream Hardness
_ _ _ _ _ _
I 18.61 mg/L (Avg)
_Combined H_ardn_ess Chronic
_ _ _ _ _ _
_ _ _ _ _ _ _ 42.96 mg/L
Combined Hardness Acute
I 45.65 mg/L
Data from submitted DMRs and PPAs, hardness
data provided by ORC.
Data Source(s)
❑ CHECK TO APPLY MODEL
Par01
Par02
Par03
Par04
Par05
Par061111111
Par07
Par08
Par09
Par10
Par11
Par12
Par13
Par14
Par15
Par16
Par17
Par18
Par19
Par20
Par21
Par22
Par23
Par24
Table 2. Parameters of Concern
Name WQS Type Chronic Modifier Acute PQL Units
Arsenic
Aquactic Life
C
150
FW
340
ug/L
Arsenic
Human Health
Water Supply
C
10
HH/WS
N/A
ug/L
Beryllium
Aquatic Life
NC
6.5
FW
65
ug/L
Cadmium
Aquatic Life
NC
0.8881
FW
5.4798
ug/L
Chlorides
Aquatic Life
NC
230
FW
mg/1-1
Chlorinated Phenolic Compounds
Water Supply
NC
1
A
ug/L
Total Phenolic Compounds
Aquatic Life
NC
300
A
ug/L
Chromium III
Aquatic Life
NC
183.4098
FW
1482.1342
ug/L
Chromium VI
Aquatic Life
NC
11
FW
16
pg/L
Chromium, Total
Aquatic Life
NC
N/A
FW
N/A
pg/L
Copper
Aquatic Life
NC
12.5151
FW
18.4693
ug/L
Cyanide
Aquatic Life
NC
5
FW
22
10
ug/L
Fluoride
Aquatic Life
NC
1,800
FW
ug/L
Lead
Aquatic Life
NC
5.3938
FW
148.1256
ug/L
Mercury
Aquatic Life
NC
12
FW
0.5
ng/L
Molybdenum
Human Health
NC
2000
HH
ug/L
Nickel
Aquatic Life
NC
58.8548
FW
557.9259
pg/L
Nickel
Water Supply
NC
25.0000
WS
N/A
pg/L
Selenium
Aquatic Life
NC
5
FW
56
ug/L
Silver
Aquatic Life
NC
0.06
FW
0.8351
ug/L
Zinc
Aquatic Life
NC
200.4795
FW
209.3893
ug/L
21121 RPA, input
7/31 /2020

21121 RPA, input
7/31 /2020

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL H2
Effluent Hardness Values" then "COPY". Upstream Hardness
Maximum data points
= 58
Date
Data
BDL=1/2DL
1/8/2019
57.2
57.2
2/4/2019
47.8
47.8
3/4/2019
61.8
61.8
4/2/2019
108
108
5/6/2019
74.2
74.2
6/3/2019
80.5
80.5
8/5/2019
58.2
58.2
9/3/2019
82.6
82.6
10/8/2019
116
116
11/4/2019
65.7
65.7
12/2/2019
86.1
86.1
1/14/2020
78.5
78.5
Results
Std Dev.20.3845
Mean
76.3833
C.V.
0.2669
n
12
10th Per value
57.30 mg/L
Average Value
76.38 mg/L
Max. Value
116.00 mg/L
Use"PASTE SPECIAL
Values" then "COPY"
Maximum data points
= 58
Date
Data
BDL=1/2DL
Results
1 9/6/2016
19.4
19.4
Std Dev.
1.0619
2 10/4/2016
20.6
20.6
Mean
18.6130
3 11/1/2016
20.6
20.6
C.V.
0.0570
4 12/5/2016
20.4
20.4
n
23
5 1/10/2017
18
18
10th Per value
17.54 mg/L
6 2/1/2017
18.4
18.4
Average Value
18.61 mg/L
7 3/1/2017
17.5
17.5
Max. Value
20.60 mg/L
8 4/4/2017
18
18
9 5/1/2017
18.2
18.2
10 6/1/2017
16.6
16.6
11 7/11/2017
18
18
12 8/1/2017
19.2
19.2
13 9/5/2017
18
18
14 10/10/2017
18
18
15 11/6/2017
18.2
18.2
16 12/4/2017
17.5
17.5
17 1/9/2018
17.8
17.8
18 2/5/2018
17.7
17.7
19 3/5/2018
19.2
19.2
20 4/10/2018
18.9
18.9
21 5/7/2018
18.7
18.7
22 6/4/2018
19.4
19.4
23 7/10/2018
19.8
19.8
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
-1-
21121 RPA, data
7/31 /2020

REASONABLE POTENTIAL ANALYSIS
& Par02
Date Data
1
2
3
4
5
6
7 10/10/2017 <
8 1/9/2018 <
9 4/10/2018 <
10 7/10/2018 <
11 10/2/2018 <
12 1/8/2019 <
13 4/2/2019 <
14 7/9/2019 <
15 10/8/2019 <
16 1/14/2020 <
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
10
10
10
10
5
10
10
10
10
10
Arsenic
BDL=1/2DL
Results
Std Dev.
Mean
C.V.
n
Mult Factor =
5
Max. Value
5
Max. Pred Cw
5
5
2.5
5
5
5
5
5
Use"PASTE SPECIAL
Values" then "COPY"
Maximum data points
= 58
4.7500
0.1664
10
1.18
5.0 ug/L
5.9 ug/L
-2-
21121 RPA, data
7/31 /2020

REASONABLE POTENTIAL ANALYSIS
Ir03
Beryllium
Use"PASTE SPECIAL
Values" then "COPY".
Par04
Maximum data points
= 58
Date Data
BDL=1/2DL
Results
Date
Data
1 7/10/2015 <
10 5
Std Dev.
0.0000
1
1/14/2020
<
2 1/10/2017 <
10 5
Mean
5.0000
2
4/5/2016
<
3
C.V. (default)
0.6000
3
7/12/2016
<
4
n
2
4
10/4/2016
<
5
5
1/10/2017
<
6
Mult Factor =
3.79
6
4/4/2017
<
7
Max. Value
5.00 ug/L
7
7/11/2017
<
8
Max. Pred Cw
18.95 ug/L
8
10/10/2017
<
9
9
1/9/2018
<
10
10
4/10/2018
<
11
11
7/10/2018
<
12
12
10/2/2018
<
13
13
1/8/2019
<
14
14
4/2/2019
<
15
15
7/9/2019
<
16
16
10/8/2019
<
17
17
1/14/2020
<
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
Cadmium
BDL=1/2DL
Results
2 1
Std Dev.
2 1
Mean
2 1
C.V.
2 1
n
2 1
2 1
Mult Factor =
2 1
Max. Value
2 1
Max. Pred Cw
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
2 1
Use"PASTE SPECIAL
Values" then "COPY"
Maximum data points
= 58
1.0000
0.0000
17
1.00
1.000 ug/L
1.000 ug/L
21121 RPA, data
-3- 7/31/2020

REASONABLE POTENTIAL ANALYSIS
Use"PASTE SPECIAL- Par06 Use "PASTE SF
Chlorides Values tnen c.Pr . Chlorinated Phenolic Compounds Values " then "C
Maximum data points= Maximum data
58 = 58
Date Data
BDL=1/2DL
Results
1 4/5/2016
37.2
37.2
Std Dev.
2 7/12/2016
50.4
50.4
Mean
3 10/4/2016
36.7
36.7
C.V.
4 1/10/2017
55.6
55.6
n
5 4/4/2017
37
37
6 7/11/2017
50.5
50.5
Mult Factor =
7 10/10/2017
33.2
33.2
Max. Value
8 1/9/2018
52
52
Max. Pred Cw
9 4/10/2018
53.4
53.4
10 7/10/2018
78.7
78.7
11 10/2/2018
46.5
46.5
12 1/8/2019
33.9
33.9
13 4/2/2019
44.2
44.2
14 7/9/2019
55.1
55.1
15 10/8/2019
47
47
16 1/14/2020
38
38
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Date Data
1
BDL=1/2DL Results
Std Dev.
NO DATA
46.8
2
Mean
NO DATA
0.2457
3
C.V.
NO DATA
16
4
n
0
5
1.2
6
Mult Factor =
N/A
78.7 mg/L
7
Max. Value
N/A
92.9 mg/L
8
Max. Pred Cw
N/A
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
21121 RPA, data
-4- 7/31/2020

REASONABLE POTENTIAL ANALYSIS
IECIAL
:OPY" .
points
Par07
1
Date
7/16/2015
Total Phenolic Compounds
Data BDL=1/2DL
< 5 2.5
Results
Std Dev.
Use"PASTE SPECIAL
Values" then "COPY".
Maximum data points
= 58
1.4434
Par08
Date
1
Chromium III
Data BDL=1/2DL Results
Std Dev.
Use"PASTE SF
Values" then "C
Maximum data
= 58
2
10/28/2016
< 10 5
Mean
3.3333
2
Mean
NO DATA
3
1/27/2017
< 5 2.5
C.V. (default)
0.6000
3
C.V.
NO DATA
4
n
3
4
n
0
5
5
6
Mult Factor =
3.00
6
Mult Factor =
N/A
ug/L
7
Max. Value
5.0 ug/L
7
Max. Value
N/A
ug/L
8
Max. Pred Cw
15.0 ug/L
8
Max. Pred Cw
N/A
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
21121 RPA, data
-5- 7/31/2020

REASONABLE POTENTIAL ANALYSIS
-CIAL Par09
:O PY" .
points
Date
Data
1
2
3
4
5
6
Ng/L
7
Ng/L
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Chromium VI
BDL=1/2DL Results
Std Dev.
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Pred Cw
Par10
Use"PASTE SPECIAL
Values" then "COPY .
Chromium, Total
Maximum data points
= 58
Date
Data
BDL=1/2DL
Results
1
4/5/2016
<
5
2.5
Std Dev.
NO DATA
2
7/12/2016
<
5
2.5
Mean
NO DATA
3
10/4/2016
<
5
2.5
C.V.
0
4
1/10/2017
<
5
2.5
n
5
4/4/2017
<
5
2.5
N/A
6
7/11/2017
<
5
2.5
Mult Factor =
N/A Ng/L
7
10/10/2017
<
5
2.5
Max. Value
N/A Ng/L
8
1/9/2018
<
5
2.5
Max. Pred Cw
9
4/10/2018
<
5
2.5
10
7/10/2018
<
5
2.5
11
10/2/2018
<
5
2.5
12
1/8/2019
<
5
2.5
13
4/2/2019
<
5
2.5
14
7/9/2019
<
5
2.5
15
10/8/2019
<
5
2.5
16
1/14/2020
<
5
2.5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Use "PASTE SF
Values" then '•C
Maximum data
= 58
2.5000
0.0000
16
1.00
2.5
2.5
-6-
21121 RPA, data
7/31 /2020

REASONABLE POTENTIAL ANALYSIS
IECIAL Pal
pointCopper
pointss
Date Data
BDL=1/2DL
Results
1
4/5/2016
10
10
Std Dev.
2
7/12/2016
30
30
Mean
3
10/4/2016
14
14
C.V.
4
1/10/2017
36
36
n
5
4/4/2017
11
11
6
7/11/2017
23
23
Mult Factor =
Ng/L
7
10/10/2017
6
6
Max. Value
Ng/L
8
1/9/2018
7
7
Max. Pred Cw
9
4/10/2018
12
12
10
7/10/2018
13
13
11
10/2/2018
7
7
12
1/8/2019
12
12
13
4/2/2019
21
21
14
7/9/2019
13
13
15
10/8/2019
10
10
16
1/14/2020
6
6
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Use"PASTE SPECIAL Par12 Use"PASTE SF
✓alues" then "COPY" . Cyanide Values" then "C
Maximum data points Maximum data
= 58 = 58
1
Date
4/5/2016
Data
<
10
BDL=1/2DL
5
Results
Std Dev.
77727-
14.4375
2
7/12/2016
<
10
5
Mean
0.6049
3
10/4/2016
<
10
5
C.V.
16
4
1/10/2017
<
10
5
n
5
4/4/2017
<
10
5
1.47
6
7/11/2017
<
10
5
Mult Factor =
36.00 ug/L
7
10/10/2017
<
10
5
Max. Value
52.92 ug/L
8
1/9/2018
<
10
5
Max. Pred Cw
9
4/10/2018
<
10
5
10
7/10/2018
<
5
5
11
10/2/2018
<
5
5
12
1/8/2019
<
10
5
13
4/2/2019
<
10
5
14
7/9/2019
<
5
5
15
10/8/2019
<
10
5
16
1/14/2020
<
10
5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
5.00
0.0000
16
1.00
5.0
5.0
21121 RPA, data
-7- 7/31/2020

REASONABLE POTENTIAL ANALYSIS
IECIAL
Par13
Use"PASTE SPECIAL
Par14
Lead
:OPY" .
points
Fluoride
Values" then "COPY".
Maximum data points
= 58
Date Data
1
BDL=1/2DL Results
Std Dev.
NO DATA
1
Date
4/5/2016
< 10
BDL=1/2DL
5
Results
Std Dev.
2
Mean
NO DATA
2
7/12/2016
< 10
5
Mean
3
C.V.
NO DATA
3
1/10/2017
< 10
5
C.V.
4
n
0
4
4/4/2017
< 10
5
n
5
5
7/11/2017
< 10
5
6
Mult Factor =
N/A
6
10/10/2017
< 10
5
Mult Factor =
ug/L
7
Max. Value
N/A ug/L
7
1/9/2018
< 10
5
Max. Value
ug/L
8
Max. Pred Cw
N/A ug/L
8
4/10/2018
< 10
5
Max. Pred Cw
9
9
7/10/2018
< 10
5
10
10
10/2/2018
< 10
5
11
11
1/8/2019
< 10
5
12
12
4/2/2019
< 10
5
13
13
7/9/2019
< 10
5
14
14
10/8/2019
< 10
5
15
15
1/14/2020
< 10
5
16
16
17
17
18
18
19
19
20
20
21
21
22
22
23
23
24
24
25
25
26
26
27
27
28
28
29
29
30
30
31
31
32
32
33
33
34
34
35
35
36
36
37
37
38
38
39
39
40
40
41
41
42
42
43
43
44
44
45
45
46
46
47
47
48
48
49
49
50
50
51
51
52
52
53
53
54
54
55
55
56
56
57
57
58
58
Use "PASTE SF
Values" then "C
Maximum data
= 58
5.0000
0.0000
15
1.00
5.000
5.000
21121 RPA, data
-8- 7/31/2020

REASONABLE POTENTIAL ANALYSIS
1ECIAL Par15
:O PY" .
points
1
2
3
4
5
6
ug/L 7
ug/L 8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Mercury
Date Data BDL=1/2DL Results
Std Dev.
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Pred Cw
Use "PASTE SPECIAL Par16 Use "PASTE SF
✓alues" then "COPY" . Molybdenum Values" then "C
Maximum data points Maximum data
= 58 = 58
1
Date
4/5/2016
Data
<
100
BDL=1/2DL
50
Results
Std Dev.
NO DATA
NO DATA
2
7/12/2016
<
100
50
Mean
NO DATA
3
10/4/2016
<
100
50
C.V.
0
4
1/10/2017
<
100
50
n
5
4/4/2017
<
100
50
N/A
6
7/11/2017
<
100
50
Mult Factor =
N/A ng/L
7
10/10/2017
<
100
50
Max. Value
N/A ng/L
8
1/9/2018
<
100
50
Max. Pred Cw
9
4/10/2018
<
100
50
10
7/10/2018
<
100
50
11
10/2/2018
<
100
50
12
1/8/2019
<
10
5
13
4/2/2019
<
100
50
14
7/9/2019
<
100
50
15
10/8/2019
<
100
50
16
1/14/2020
<
100
50
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
47.1875
0.2384
16
1.18
50.0
59.0
-9-
21121 RPA, data
7/31 /2020

REASONABLE POTENTIAL ANALYSIS
IECIAL
Par17 & Par18
Use "PASTE SPECIAL
Par19
Selenium
:OPY" .
points
Nickel
Values" then "COPY" .
Maximum data points
= 58
1
Date
4/5/2016
Data
<
10
BDL=1/2DL
5
Results
Std Dev.
0.0000
1
Date
4/5/2016
Data
<
10
BDL=1/2DL
5
Results
Std Dev.
2
7/12/2016
<
10
5
Mean
5.0000
2
7/12/2016
<
10
5
Mean
3
10/4/2016
<
10
5
C.V.
0.0000
3
10/4/2016
<
10
5
C.V.
4
1/10/2017
<
10
5
n
16
4
1/10/2017
<
10
5
n
5
4/4/2017
<
10
5
5
4/4/2017
<
10
5
6
7/11/2017
<
10
5
Mult Factor =
1.00
6
7/11/2017
<
10
5
Mult Factor =
ug/L
7
10/10/2017
<
10
5
Max. Value
5.0 Ng/L
7
10/10/2017
<
10
5
Max. Value
ug/L
8
1/9/2018
<
10
5
Max. Pred Cw
5.0 Ng/L
8
1/9/2018
<
10
5
Max. Pred Cw
9
4/10/2018
<
10
5
9
4/10/2018
<
10
5
10
7/10/2018
<
10
5
10
7/10/2018
<
10
5
11
10/2/2018
<
10
5
11
10/2/2018
<
10
5
12
1/8/2019
<
10
5
12
1/8/2019
<
10
5
13
4/2/2019
<
10
5
13
4/2/2019
<
10
5
14
7/9/2019
<
10
5
14
7/9/2019
<
10
5
15
10/8/2019
<
10
5
15
10/8/2019
<
10
5
16
1/14/2020
<
10
5
16
1/14/2020
<
10
5
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
21121 RPA, data
-10- 7/31/2020

REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Paf20
Values" then "COPY" .
Maximum data points
= 58
Date
Data
1
4/5/2016
<
5.0000
2
7/12/2016
<
0.0000
3
10/4/2016
<
16
4
1/10/2017
<
5
4/4/2017
<
1.00
6
7/11/2017
<
5.0 ug/L
7
10/10/2017
<
5.0 ug/L
8
1/9/2018
<
9
4/10/2018
<
10
7/10/2018
<
11
10/2/2018
<
12
1/8/2019
<
13
4/2/2019
<
14
7/9/2019
<
15
10/8/2019
<
16
1/14/2020
<
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Silver
Use"PASTE SPECIAL
Values" then "COPY".
Par21
ZincMaximum
data points
= 58
BDL=1/2DL
Results
Date Data
BDL=1/2DL
Results
i 2.5
Std Dev.
1
4/5/2016
77
77
Std Dev.
i 2.5
Mean
1.1250
2
7/12/2016
82
82
Mean
i 2.5
C.V.
0.8510
3
10/4/2016
38
38
C.V.
i 2.5
n
16
4
1/10/2017
65
65
n
0.5
5
4/4/2017
520
520
i 2.5
Mult Factor =
1.67
6
7/11/2017
40
40
Mult Factor =
0.5
Max. Value
2.500 ug/L
7
10/10/2017
49
49
Max. Value
0.5
Max. Pred Cw
4.175 ug/L
8
1/9/2018
60
60
Max. Pred Cw
0.5
9
4/10/2018
47
47
0.5
10
7/10/2018
115
115
0.5
11
10/2/2018
31
31
0.5
12
1/8/2019
54
54
0.5
13
4/2/2019
62
62
0.5
14
7/9/2019
440
440
0.5
15
10/8/2019
43
43
0.5
16
1/14/2020
37
37
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
21121 RPA, data
11 - 7/31/2020

REASONABLE POTENTIAL ANALYSIS
Use"PASTE SPECIAL
Par22
0
Values" then "COPY" .
Maximum data points
= 58
Date Data BDL=1/2DL Results
1 Std Dev.
146.6733
110.0000
2 Mean
1.3334
3 C.V.
16
4 n
5
2.02
6 Mult Factor =
520.0 ug/L
7 Max. Value
1050.4 ug/L
8 Max. Pred Cw
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Use"PASTE SPECIALI Par23
Values" then "COPY" .
Maximum data points
= 58
NO DATA
NO DATA
0
N/A
N/A
N/A
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Date Data
0
BDL=1/2DL
-12-
21121 RPA, data
7/31 /2020

REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL
Values" then "COPY" .
- ---
0
Maximum data points
= 58
Results
Date Data
BDL=1/2DL Results
Std Dev.
NO DATA
1
Std Dev.
Mean
NO DATA
2
Mean
C.V.
NO DATA
3
C.V.
n
0
4
n
5
Mult Factor =
N/A
6
Mult Factor =
Max. Value
N/A
7
Max. Value
Max. Pred Cw
N/A
8
Max. Pred Cw
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Use"PASTE SPECIAL Par25
✓alues" then "COPY" f-
Maximum data points
= 58
NO DATA
NO DATA
0
N/A
N/A
N/A
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Date Data
0
BDL=1/2DL
21121 RPA, data
-13- 7/31/2020

REASONABLE POTENTIAL ANALYSIS
Use"PASTE SPECIAL
Values" then "COPY".
Maximum data points
= 58
Results
Mean NO DATA
C.V. NO DATA
Mult Factor = N/A
Max. Value N/A
Max. Pred Cw N/A
-14-
21121 RPA, data
7/31 /2020

Mount Airy WWTP I Outfall 001
NCO021121 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 7 MGD
MAXIMUM DATA POINTS = 58
Qw (MGD) =
7.0000
WWTP/WTP Class: IV
1Q10S (cfs) =
12.33
IWC% @ 1Q10S = 46.80759275
7Q10S (cfs) =
14.90
IWC% @ 7Q10S = 42.13592233
7Q10W (cfs) =
31.00
IWC% @ 7Q10W = 25.92592593
30Q2(cfs)=
NO30Q2DATA
IWC% @30Q2= N/A
Avg. Stream Flow, QA (cfs) =
NO QA DATA
IW°/uC @ QA = N/A
Receiving Stream:
Aratat River H UC 03040101
Stream Class: C
COMBINED HARDNESS (mg/L)
Acute = 45.65 mg/L
Chronic = 42.96 mg/L
PARAMETER
NC STANDARDS OR EPA CRITERIA
J
F
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
TYPE
a
�
Chronic Appli
Acute
n # Det. Max Pred Cw Allowable Cw
d
StandAcute
(FW): 726.4
Arsenic
C
150 FW(7Q10s) 340
ug/L
10 0
5.9
Chronic (FW): 356.0
No detects at < 5 and < 10 ug/L No limits or
Maas MDL = 10
monitoring required.
Arsenic
C
10 HHIWS(Qavg)
ug/L
NO DETECTS
Chronic (F113): IWC?
Max MDL = 10
Acute: 138.87
Beryllium
NC
6.5 FW(7Q10s) 65
ug/L
2 0
18.95
Note: n < 9
C.V. (default)
Chronic: 15.43
No detects at < 10 ug/L. No limits or monitoring
Limited data set
NO DETECTS
Max MDL = 10
required.
Acute: 11.707
Cadmium
NC
0.8881 FW(7Q10s) 5.479E
ug/L
17 0
1.000
Chronic: 2.108
No detects at < 2 ug/L No limits or monitoring
NO DETECTS
Max MDL=2
required.
Acute: NO WQS
Chlorides
NC
230 FW(7Q10s)
ma L
16 16
92.9
Chronic: 545.9
No RP, Predicted Max < 50 % of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Chlorinated Phenolic Compounds
NC
1 A(30Q2)
ua L
0 0
N/A
Chronic: -----IWC?--
---------------------------
Acute: NO WQS
Total Phenolic Compounds
NC
300 A(30Q2)
ug/L
3 0
15.0
Note: n < 9
C.V. (default)
Chronic: IWC?
No detects at < 5 and < 10 ug/L No limits or
Limited data set
NO DETECTS
Max MDL = 10
monitoring required.
Acute: 3,166.4
Chromium III
NC
183.4098 FW(7Q10s) 1482.1342
µg/L
0 0
N/A
1
Chronic: -----435.3--
---------------------------
Acute: 34.2
ChromiumVI
NC
11 FW(7Q10s) 16
µg'L
0 0
N/A
Chronic:----- 26.1 --
---------------------------
Chromium, Total
NC
µg/L
16 0
2.5
Max reported value = 2.5
No detects at < 5 ug/L No limits or monitoring
required.
NO DETECTS
Maas MDL = 5
Acute: 39.46
Copper
NC
12.5151 FW(7Q10s) 18.4693
ug/L
16 16
52.92
_ _ _ _ _ _
Chronic: - - 29.70
_ _ _ _ _ _ _ _ _ _ _ _
pD chnu n nnhi Mnn4hly Mnni4nrinn u, i+h I -i4 -
21121 RPA, rpa
Page 1 of 3 7/31/2020

Mount Airy WWTP I Outfall 001
NCO021121 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 7 MGD
2 values > Allowable Cw
Acute: 47.0
Cyanide
NC
5 FW(7Q10s) 22
10
ug/L
16 0
5.0
Chronic: 11.9
No detects at < 10 ug/L. No limits or monitoring
NO DETECTS
Maas MDL = 10
required.
Acute: NO WQS
Fluoride
NC
1800 FW(7Q10s)
ug/L
0 0
N/A
Chronic:---- 4,271.9
------
Acute: 316.456
Lead
NC
5.3938 FW(7Q10s) 148.1256
ug/L
15 0
5.000
Chronic: 12.801
No detects at < 10 ug/L. No limits or monitoring
NO DETECTS
Maas MDL = 10
required.
Acute: NO WQS
Mercury
NC
12 FW(7Q10s)
0.5
ne/L
0 0
N/A
Chronic:----- 28.5 --
---------------------------
Acute: NO WQS
Molybdenum
NC
2000 HH(7Q10s)
ug/L
16 0
59.0
Chronic: 4,746.5
No detects at < 100 and < 10 ug/L No limits or
NO DETECTS
Max MDL =100
moitonng required.
Acute (FW): 1,192.0
Nickel
NC
58.8548 FW(7Q10s) 557.9259
µg/L
16 0
5.0
_ _ ____ ___
Chronic (FW): 139.7
___________________________
MEEc DL_=10
Nickel
NC
25.0000 WS(7Q10s)
µg/L
NO DETECTS
___
Chronic (WS): 59.3
_ _ _ _ _ _ _ _ _ _ _ _ ___
No detects at < 10 ug/L. No limits or monitoring
Maas MDL = 10
required.
Acute: 119.6
Selenium
NC
5 FW(7Q10s) 56
ug/L
16 0
5.0
Chronic: 11.9
No detects at < 10 ug/L. No limits or monitoring
NO DETECTS
Maas MDL = 10
required.
Acute: 1.784
Silver
NC
0.06 FW(7Q10s) 0.8351
ug/L
16 0
4.175
Chronic: 0.142
No detects at < 1 ug/L in the past year No limits or
NO DETECTS
Max MDL =5
monitoring required.
Acute: 447.3
Zinc
NC
200.4795 FW(7Q10s) 209.3893
ug/L
16 16
1,050.4___
Chronic: 475.8
RP shown apply Monthly Monitoring with Limit
1 values > Allowable Cw
Acute:
0 0
N'A
Chronic: ----------
---------------------------I
Acute:
0 0
N/A
__ _ _ - - - - - - - - - -
Chronic:
- - - - - - - - - - - - - - - - - - - - - - - - - - -
Acute:
0 0
N/A
__ _ _ - - - - - - - - - -
Chronic:
- - - - - - - - - - - - - - - - - - - - - - - - - - -
Acute:
0 0
N/A
----------------
---------------------------I
21121 RPA, rpa
Page 2 of 3 7/31/2020

Mount Airy WWTP
Outfall 001
NCO021121 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators _ _ Qw = 7 MG
Chronic:
21121 RPA, rpa
Page 3 of 3 7/31/2020

FACILITY: Mount Airy WWTP Outfall 001
NPDES PERMIT: NCO021121
Dissolved to Total Metal Calculator
In accordance with Federal Regulations, permit limitations must be written as Total Metals per 40 CFR 122.45(c)
Receiving
Receiving
Rec. Stream
NPDES Total Suspended
Combined
Combined
Instream
Instream
Effluent
Stream
Stream
Solids
Hardness
Hardness
Wastewater
Wastewater
Upstream
Hardness
summer
sunmer7Q10
1Q10
Flow Limit
-Fixed Value-
chronic
Acute
Concentration
Concentration
Hardness
Average (mg/L)
Average
7Q10(CFS)
(MGD)
[MGD]
[MGD] (mg/L)
(mg/L)
(mg/L)
(Chronic)
(Acute)
(mg/L)
14.9000
9.6129 11
7.9548
7.0000 10
42.955
11 45.654
11 42.1359
46.8076
1 18.6130435
176.38333
Dissolved Metals Criteria
US EPA
Total Metal Criteria Total Metal
after applying hardness
Translators- using
PARAMETER
equation
l
Default
=oissolvedMeal-Tanslaor
Chronic F Acute
Chronic Acute
Coefficients
u l u /I
u /I u /I
streams
Cadmium (d)
1.38
0.252
0.89 5.48
Cd -Trout streamsEO.22
0.22
0252
0.89 3.41
Chromium III (d)(h)37
0.202
183.41 1482.13
Chromium VI (d)
7300
11
1.000
11.00 16.00
Chromium, Total (t)
NIA NIA
Copper (d)(h)
4.4
0.348
12.52 18.47
Lead (d)(h)
0.99 27
U.
5.39 148.13
Nickel (d)(h)
25 241
0.432
58.85 557.93
Ni - WS streams (t)
25 NIA
Silver (d)(h,acute)
0.06 0.84
1.000
0.061 0.84
Zinc (d)(h)
58 60
0.288
200.48 209.39
IBervllium 7 1 6.51 - 1.0001 ifd
Upstream Hard Avg (mg/L) = 16.61304
EFF Hard Avg (mg/L) = 76.38333
(identify parameters to PERCS Branch to maintain in facility's LTMP/STMP):
(d) = dissolved metal standard. See 15A NCAC 02B .0211 for more information.
(h) = hardness -dependent dissolved metal standard. See 15A NCAC 02B .0211 for more information.
(t) = based upon measurement oftotal recoveable metal. See 15A NCAC 02B .0211 for more information.
The Human Health standard for Nickel in Water Supply Streams is 25 mg/L which is Total Recoverable metal standard.
The Human Health standard for Arsenic is 10 µg/L which is Total Recoverable metal standard.

Permit No. NC0021121
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
(Dissolved)
Chronic FW, µg/1
(Dissolved)
Acute SW, µg/1
(Dissolved)
Chronic SW, µg/l
(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:
FW= Freshwater, SW= Saltwater
Calculation = Hardness dependent standard
Only the aquatic life standards listed above are expressed in dissolved form. Aquatic life
standards for Mercury and selenium are still expressed as Total Recoverable Metals due to
bioaccumulative concerns (as are all human health standards for all metals). It is still necessary
to evaluate total recoverable aquatic life and human health standards listed in 15A NCAC
213.0200 (e.g., arsenic at 10 µg/l 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)} eA10.9151 [In hardness]-3.1485}
Cadmium, Acute Trout waters
WER* { 1.136672-[ln hardness](0.041838)} e 10.915I [In hardness] -3.623 61
Cadmium, Chronic
WER* {1.101672-[ln hardness](0.041838)} e^{0.7998[ln hardness]-4.4451 }
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 eA fO.9422[ln hardness]-1.7001
Copper, Chronic
WER*0.960 e A f 0.8545 [In hardness] - 1.7021
Lead, Acute
WER* {1.46203-[ln hardness](0.145712)1 • eAl1.273[In hardness]-1.4601
Lead, Chronic
WER* {1.46203-[ln hardness](0.145712)1 • e^{1.273[lnhardness] -4.705}
Nickel, Acute
WER*0.998 eA f 0.8460[ln hardness]+2.255 }
Nickel, Chronic
WER*0.997 eA10.8460[ln hardness]+0.0584}
Page 1 of 4

Permit No. NCO021121
Silver, Acute
WER*0.85 • e^{1.72[ln hardness]-6.59}
Silver, Chronic
Not applicable
Zinc, Acute
WER*0.978 eA f 0.8473[In hardness]+0.8841
Zinc, Chronic
WER*0.986 eA f 0.8473[In hardness]+0.8841
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/WQBELs for Hardness -Dependent Metals - Freshwater
The RPA is designed to predict the maximum likely effluent concentrations for each metal of concern,
based on recent effluent data, and calculate the allowable effluent concentrations, based on applicable
standards and the critical low -flow values for the receiving stream.
If the maximum predicted value is greater than the maximum allowed value (chronic or acute), the
discharge has reasonable potential to exceed the standard, which warrants a permit limit in most cases. If
monitoring for a particular pollutant indicates that the pollutant is not present (i.e. consistently below
detection level), then the Division may remove the monitoring requirement in the reissued permit.
To perform a RPA on the Freshwater hardness -dependent metals the Permit Writer compiles the
following information:
• Critical low flow of the receiving stream, 7Q10 (the spreadsheet automatically calculates
the 1 Q 10 using the formula 1 Q 10 = 0.843 (s7Q 10, cfs) 0.993
• Effluent hardness and upstream hardness, site -specific data is preferred
• Permitted flow
• Receiving stream classification
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. NCO021121
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 1Q10 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 - I
Ctotal I + { [Kpo] [ss(I+a)] [10 6] i
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 (le. 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 = (s7Q10 + Qw) (Cwgs) — (s7Q10) (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 s7Q10)
s7Q10 = 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 s7Q10 may be incorporated as applicable:
1Q10 = used in the equation to protect aquatic life from acute toxicity
Page 3 of 4

Permit No. NC0021121
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
The permit writer enters the most recent 2-3 years of effluent data for each pollutant of concern.
Data entered must have been taken within four and one-half years prior to the date of the permit
application (40 CFR 122.21). The RPA spreadsheet estimates the 95th percentile upper
concentration of each pollutant. The Predicted Max concentrations are compared to the Total
allowable concentrations to determine if a permit limit is necessary. If the predicted max exceeds
the acute or chronic Total allowable concentrations, the discharge is considered to show
reasonable potential to violate the water quality standard, and a permit limit (Total allowable
concentration) is included in the permit in accordance with the U.S. EPA Technical Support
Document for Water Quality -Based Toxics Control published in 1991.
7. When appropriate, permit writers develop facility specific compliance schedules in accordance
with the EPA Headquarters Memo dated May 10, 2007 from James Hanlon to Alexis Strauss on
40 CFR 122.47 Compliance Schedule Requirements.
The Total Chromium NC WQS was removed and replaced with trivalent chromium and
hexavalent chromium Water Quality Standards. As a cost savings measure, total chromium data
results may be used as a conservative surrogate in cases where there are no analytical results
based on chromium III or VI. In these cases, the projected maximum concentration (95th %) for
total chromium will be compared against water quality standards for chromium III and
chromium VI.
9. Effluent hardness sampling and instream hardness sampling, upstream of the discharge, are
inserted into all permits with facilities monitoring for hardness -dependent metals to ensure the
accuracy of the permit limits and to build a more robust hardness dataset.
10. Hardness and flow values used in the Reasonable Potential Analysis for this permit included:
Parameter
Value
Comments (Data Source)
Average Effluent Hardness, mg/L
76.38
Data provided by Permittee
(Total as CaCO3)
Average Upstream Hardness, mg/L
18.61
Data provided by Permittee
(Total as CaCO3)
7Q10 summer (cfs)
14.9
Reported in previous permit Fact
Sheet
1Q10 (cfs)
12.33
Calculated in RPA spreadsheet
Permitted Flow (MGD)
7.0
Design flow
Date: July 31, 2020
Permit Writer: Gary Perlmutter
Page 4 of 4

Data Summary for HARDNESS
DATE EFFLUENT UPSTREAM
7/7/2015
52.9
8/4/2015
44.6
9/1/2015
43.2
10/13/2015
48.3
11/10/2015
49
12/8/2015
52.5
1/5/2016
56.4
2/1/2016
51.9
3/1/2016
52.5
4/5/2016
48.5
5/2/16
47.5
6/1/16
49
7/12/16
50.5
8/1/16
42.8
9/6/16
56.1
19.4
10/4/16
47.9
20.6
11/1/16
47.4
20.6
12/5/16
42.8
20.4
1/10/17
47
18
2/1/17
49
18.4
3/1/17
56.6
17.5
4/4/17
48
18
5/1/17
49.5
18.2
6/1/17
48.9
16.6
7/11/17
46
18
8/1/17
42.4
19.2
9/5/17
43
18
10/10/17
38.2
18
11/6/17
49.5
18.2
12/4/17
46.4
17.5
1/9/18
76
17.8
2/5/18
149
17.7
3/5/18
84.8
19.2
4/10/18
72.4
18.9
5/7/18
106
18.7
6/4/18
77.5
19.4
7/10/18
88.4
19.8
AVERAGE
MAXIMUM
MINIUM
56.82
18.61
149
20.6
38.2
16.6
NOTE: All data in mg/I

Mercury Minimization Plan (MMP) Summary
for NPDES Renewal — August 2018
The City of Mount Airy developed a MMP on January 29, 2015. The
following is a summary of activities:
• Various information was used to determine the potential for users of
the sewer system to contribute mercury.
• A list of system of users, both domestic & non -domestic, was
developed.
• The list of users was surveyed and the City continues to survey ten
percent (10%) of these users annually.
• Substances containing mercury at the WWTP, including the
laboratory, were evaluated and replaced wherever practical.
• Spill control measures and personnel training have been addressed in
the City's Spill Prevention and Chemical Hygiene Plans.
• New sources of non -domestic mercury are being surveyed along with
Industrial Waste Surveys as necessary.
• Educational information regarding sources of household mercury,
disposal practices, and community collection points are posted on the
City's website. This information is also included with a monthly water
bill annually.
• The City has and continues to monitor influent and effluent mercury
concentrations quarterly as per its Long Term Monitoring Plan
(LTMP)

5/27/20 WQS
= 12
ng/L
MERCURY WQBEL/TBEL EVALUATION
V:2013-6
Facility Name
Mt Airy
WWTP / NC0021121
No Limit Required
/Permit No.
MMP Required
Total Mercury 1631E PQL =
0.5 ng/L
7Q10s = 14.900 cfs WQBEL = 28.48 ng/L
Date Modifier
Data Entry
Value
Permitted Flow = 7.000
47 ng/L
1/10/17
6.28
6.28
4/4/17
2.42
2.42
7/11/17
7.83
7.83
10/10/17
6.43
6.43
5.7 ng/L
- Annual Average for 2017
1/9/18
4.32
4.32
4/10/18
1.32
1.32
7/10/18
1.64
1.64
10/2/18
1.56
1.56
2.2 ng/L
- Annual Average for 2018
1/8/19
3.48
3.48
4/2/19
1.87
1.87
7/9/19
5.07
5.07
10/8/19
3.05
3.05
3.4 ng/L
- Annual Average for 2019
1/14/20
2.82
2.82
2.8 ng/L
- Annual Average for 2020

Mt Airy WWTP / NCO021121
Mercury Data Statistics (Method 1631E)
2017
2018
2019
2020
# of Samples
4
4
4
1
Annual Average, ng/L
5.7
2.2
3.4
2.8
Maximum Value, ng/L
7.83
4.32
5.07
2.82
TBEL, ng/L
47
WOBEL, ng/L
28.5

Answers to questions from Chris Marion (ORC/Permittee) during draft permit public comment period.
What is meant by Regulatory citations have been added?
Regulatory citations are the citations to state rules that each permit section refer to and are in brackets
following the section header. For example:
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS - Outfa11001
[15A NCAC 02B .0400 et seq., 02B .0500 et seq.]
Regulatory citation
Why has the Ammonia sample frequency increased from 3 per week to daily?
As ammonia is water quality limited, and in accordance with 15A NCAC 02B .0508 regarding minimum
requirements for Domestic Wastewater and Other Facilities Discharging Primarily Domestic (SIC 4952),
Class IV facilities shall monitor for ammonia at a frequency of at least daily.
Why has the Conductivity sample frequency increased from weekly to daily?
In accordance with 15A NCAC 02B .0508 regarding minimum requirements for Domestic Wastewater
and Other Facilities Discharging Primarily Domestic (SIC 4952), Class IV facilities shall monitor for
conductivity at a frequency of at least daily. However, since a review of the instream and effluent data
found the effluent not to impact the instream conductivity, and a review of past permits revealing
weekly monitoring for effluent conductivity, the frequency will be reset to weekly.
Why does Copper have both monthly average and daily max limits and Zinc doesn't?
Calculation of zinc limits resulted with the daily maximum to be lower than the monthly average, which
is counterintuitive and can cause problems in compliance should a sample be above the daily maximum
yet lower than the monthly average. Therefore, we did not include a daily maximum limit for zinc. This
is a special case with zinc; all other limit calculations result in the daily max being higher than the
monthly average, and we place both in the permit, as for copper. However, to reduce confusion the
more stringent daily maximum limit has been inserted also as the monthly average limit.
Currently the eDMR system doesn't allow us to report for upstream (no page to report upstream and
downstream). Will this be updated when the permit becomes effective?
The Permittee is currently waived from submitting instream data because Mt Airy is a member of the
Yadkin -Pee Dee River Basin Association, which is why you don't have that option currently. In other
words, our database isn't currently set up to receive instream data for your permit. However, with the
proposed instream Hardness sampling our database will be modified to accept upstream Hardness data
as it will for any changes in your monitoring requirements (instream, influent or effluent) via eDMRs.
Are super compliant facilities still allowed to request reduced monitoring for BOD, TSS, Ammonia, and
Fecal Coliform? If so, what's the criteria to qualify?
Yes, there is a reduced monitoring program for exceptionally performing facilities. There are both
eligibility and data criteria for qualification. Division guidance on this program offers the following
details:
Individual NPDES facilities shall submit a written request to modify their NPDES permit specifying which
parameters are to be considered for reduced monitoring. Permit holders must include with their requests
sufficient data, statistical analyses, and other information to support the justification for reduced

monitoring.... Approval of reduced monitoring frequency shall be granted if all the criteria below are
met:
• The facility has no more than one civil penalty assessment for permit limit violations for each
target parameter during the previous three years.
• Neither the permittee nor any of its employees have been convicted of criminal violations of the
Clean Water Act within the previous five years.
• The facility is not currently under an SOC for target parameter effluent limit noncompliance.
• The facility is not on EPA's Quarterly Noncompliance Report for target parameter limit violations.
• For BODS, CBODS, TSS, NH3-N and TSS, the three year arithmetic mean of effluent data must be
less than fifty percent of the monthly average permit limit. For fecal coliform or enterococci, the
three year geometric mean must be less than 50 percent of the monthly average permit limit. For
• parameters with summer and winter limits, an annual arithmetic mean of the seasonal limits
may be used in the calculation.
• With the exception of fecal coliform or enterococci, no more than 15 daily sampling results over
the 3-year review period can be over 200% of the monthly average limit for BODS, CBODS, TSS,
or NH3-N. Values associated with documented impacts of extreme weather or events beyond
the control of the permittee will not be included.
• For fecal coliform or enterococci, no more than 20 daily sampling results may be over 200% of
the weekly average limit. Values associated with documented impacts of extreme weather or
events beyond the control of the permittee will not be included.
• For the four target parameters, sampling results shall not show more than two non -monthly
average limit violations during the previous year.
• Reduced effluent monitoring must not impair assessment of sensitive downstream uses, such as
endangered species.

CITY OF MOUNT AIRY WWTP
P. O BOX 70
MOUNT AIRY, NC 2 703 0
PHONE.- 336-786-3597
FAX.- 336-786-3573
September 11, 2020
Mr. Gary Perlmutter
NCDEQ/DWR
NPDES Permitting Branch
1617 Mail Service Center
Raleigh, NC 27699-1617
Subject: Permit Modification for a reduction in monitoring frequencies for NPDES
Permit #NC0021121
Dear Mr. Perlmutter,
The City of Mount Airy requests a minor permit modification for NPDES Permit #
NCO021121 for the reduction of monitoring frequencies from five days per week (daily)
to two days per week for the parameters of BOD, TSS, and Fecal Coliform.
The City of Mount Airy WWTP has an excellent compliance history on all fronts. Our
facility meets the eligibility criteria for the reduced monitoring under the exceptionally
performing facilities program. The City hopes this reduction, if approved, will alleviate
possible regulatory and financial burdens. Should you have any questions or need any
additional information, please contact me at [phone].
Sincerely,
� s°dam
Christopher S. Marion
WWTP Supervisor
City of Mount Airy