NC0026751_Fact Sheet_20231115

Fact Sheet
NPDES Permit No. NCOO26751
Permit Writer/Email Contact: Teresa [e-mail]
Date: November 14, 2023
Division/Branch: NC Division of Water Resources/NPDES Municipal Permitting Unit
Fact Sheet Template: Version 09Jan2017
Permitting Action:
® Renewal
❑ Renewal with Expansion
❑ New Discharge
❑ Modification (Fact Sheet should be tailored to mod request)
1. Basic Facility Information
Facility Information
Applicant/Facility Name:
Town of Windsor WWTP
Applicant Address:
P.O. Box 508, Windsor, NC 27983
Facility Address:
149 County Farm Rd., Windsor
Permitted Flow:
1.15 MGD
Facility Type/Waste:
Major Municipal; 100% domestic
Facility Class:
Grade III, Biological WPCS
Treatment Units:
Grit removal, bar screens, dual aeration basins, dual clarifiers, chlorine
contact basin, dechlorination, cascade aerator, fine solids basin, aerated
waste sludge lagoon, and backup generator.
Pretreatment Program (Y/N)
N
County:
Bertie
Region
Washington
Briefly describe the proposed permitting action and facility background: The Town of Windsor
submitted an application in October 2022 for an NPDES permit renewal at 1.15 MGD. This facility
serves a population of 3,744 residents in Windsor and Askewville. Treated wastewater is discharged via
Outfall 001 into an unnamed tributary to the Cashie River, a class C- Swamp water in the Roanoke River
Basin. There are no water intakes downstream of the facility. The Permittee' s discharge is 100%
domestic with no significant Industrial Users (SIUs) and no pretreatment program.
Since the last permit renewal the Town reconstructed the walls of the clarifiers and installed new bar
screens.
Page 1 of 12

Inflow and Infiltration (I/1): In their application, the Town noted an estimated 144,000 gpd of 1/1 is
experienced at the Windsor WWTP. The Town continues to monitor its collection system conducting
smoke testing, relining sections of pipe, replacing piping where needed and repairing pump stations when
issues arise.
Sludge disposal: Sludge is currently stored in the biosolids lagoon where it is dewatered and sent to the
sludge compost facility (WQ0002834).
2. Receiving Waterbody Information:
Receiving Waterbody Information
Outfalls/Receiving Stream(s):
UT to Cashie River
Stream Segment:
03-02-10
Stream Classification:
C-Swamp
Drainage Area (mi2):
4.1
Summer 7Q10 (cfs)
0
Winter 7Q10 (cfs):
0
30Q2 (cfs):
0
Average Flow (cfs):
4.5
IWC (% effluent):
100 %
303(d) listed/parameter:
No
Subject to TMDL/parameter:
Yes, state wide Mercury TMDL implementation
Basin/ HUC:
Roanoke River/03010107
USGS Topo Quad:
D31 NW/S Windsor, NC
3. Effluent Data Summary
Effluent data for Outfall 001 is summarized below for the period of January 1, 2019 to June 30, 2023.
Table 1. Effluent Data Summary Outfall 001
Permit
Parameter
Units
Average
Max
Min
Limit
Flow
MGD
0.566
1.81
0.01
1.15 MA
5.0 WA
BOD summer
mg/l
3.1
13.3
< 2
7.5 MA
10.0 WA
BOD winter
mg/l
4.2
61
< 2
15.0 MA
Page 2 of 12

1.0 WA
NH3N summer
mg/1
0.20
0.64
0.02
3.0 MA
2.0 WA
NH3N winter
mg/1
0.22
1.16
.018
6.0 MA
TSS
mg/1
5.6
59
< 2.5
30 WA
45 MA
6.0 > pH <
pH
SU
7.6
7.9
6.8
9.0
(geometric)
Fecal coliform
#/100 ml
24.5
61
1
WA 400
MA 200
DO
mg/1
8.7
20
6.3
DA >5.0
TRC
µg/1
11.8
41
< 10
DM 28.0
Monitor &
Temperature
° C
20.2
28.5
10
Report
TN
mg/1
13.55
23.1
2.59
Monitor and
Report
Monitor &
TP
mg/1
2.34
5.47
0.34
Report
Monitor &
Fluoride
mg/1
1.5
2.1
0.54
Report
13.8 MA
Total Copper
µg/1
10.9
56
< 10
19.4 DM
MA -Monthly Average, WA -Weekly Average, DM -Daily Maximum, DA=Daily Average
4. Instream Data Summary
Instream monitoring may be required in certain situations, for example: 1) to verify model predictions
when model results for instream DO are within 1 mg/1 of instream standard at full permitted flow; 2) to
verify model predictions for outfall diffuser; 3) to provide data for future TMDL; 4) based on other
instream concerns. Instream monitoring may be conducted by the Permittee, and there are also
Monitoring Coalitions established in several basins that conduct instream sampling for the Permittee (in
which case instream monitoring is waived in the permit as long as coalition membership is maintained).
If applicable, summarize any instream data and what instream monitoring will be proposed for this
permit action: The current permit requires instream monitoring for dissolved oxygen and temperature
upstream at the Cashie River at U.S. Hwy 17 North, and downstream at the Cashie River at the radio
tower. Upstream and downstream samples are collected 3/week during June, July, August, and
September and 1/week during the remainder of the year. The UT to the Cashie River is classified as C-
Sw waters. Swamp waters have natural characteristics due to topography, such as low velocity, dissolved
oxygen, or pH, that are different from streams draining steeper topography. The dissolved oxygen
standard of not less than a daily average of 5.0 mg/1 with an instantaneous value of not less than 4.0 mg/1
for swamp waters may have lower values if caused by natural conditions. Temperature shall not to
Page 3 of 12

exceed 2.8 degrees C (5.04 degrees F) above the natural water temperature, and in no case to exceed 32
degrees C (89.6 degrees F) for lower piedmont and coastal plain waters. Data was reviewed for the period
of January 2019 to June 2023. The data is summarized in Table 2. Below.
Table 2. Instream Monitoring Data Summary
Parameter
Units
Upstream
Downstream
Average
Max
Min
Average
Max
Min
Temperature
° C
22
30.5
4
22
31
5
DO
mg/l
5.3
12.5
1.2
5
12.2
1.3
Students t-tests were run at a 95% confidence interval to analyze relationships between instream
samples. A statistically significant difference is determined when the t-test p-value result is < 0.05.
The temperature at the downstream location exceeded 2.8 degrees C above the upstream location once in
October 2020 and once in January 2023. In both instances the effluent temperature was below the
downstream temperature. It was concluded that no statistically significant difference exists between
upstream and downstream temperature.
Upstream and Downstream DO were observed on occasion at levels below 5 mg/L [per 15A NCAC 02B
.0211 (6)] during the period reviewed. It is common for swamp waters to have low DO as is the case for
this stream. Both upstream and downstream values were similar during the periods the DO was reported
below 5 mg/l. Additionally, it was concluded that no statistically significant difference exists between
upstream and downstream DO.
No changes are proposed to instream monitoring requirements for dissolved oxygen and temperature.
Is this facility a member of a Monitoring Coalition with waived instream monitoring (YIN): NO
Name of Monitoring Coalition: NA
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): Data was reviewed for the
period of January 2019 to June 2023.The facility reported 2 daily maximum violations and 5 monthly
average violations for copper. The Town believes that the copper exceedances are caused from the
wastewater discharge from the local dye plant to the sewer system. The ORC states that they have
sampled the dye plant and copper results were elevated. The Town is in contact with the industry to
prevent future violations.
Summarize the compliance record with aquatic toxicity test limits and any second species test results
(past 5 years): The facility passed 19 of 20 quarterly chronic toxicity tests, as well as all 4 second species
chronic toxicity tests.
Page 4 of 12

Summarize the results from the most recent compliance inspection: The last facility inspection conducted
in November 2021. The facility was found in compliance.
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: 1 Q 10 streamflow (acute Aquatic Life); 7Q 10 streamflow (chronic Aquatic
Life; non -carcinogen HH); 30Q2 streamflow (aesthetics); annual average flow (carcinogen, HH).
If applicable, describe any other dilution factors considered (e.g., based on CORMIX model results): NA
If applicable, describe any mixing zones established in accordance with 15A NCAC 2B.0204(b): NA
Oxygen -Consuming Waste Limitations
Limitations for oxygen -consuming waste (e.g., BOD) are generally based on water quality modeling to
ensure protection of the instream dissolved oxygen (DO) water quality standard. Secondary TBEL limits
(e.g., BOD= 30 mg/1 for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
Ifpermit limits are more stringent than TBELs, describe how limits were developed: Both winter and
summer BOD5 limits were set based on a wasteload allocation (WLA) conducted in December of 1991.
No changes are proposed from the previous permit limits.
Ammonia and Total Residual Chlorine Limitations
Limitations for ammonia are based on protection of aquatic life utilizing an ammonia chronic criterion of
1.0 mg/1(summer) and 1.8 mg/1(winter). Acute ammonia limits are derived from chronic criteria,
utilizing a multiplication factor of 3 for Municipals and a multiplication factor of 5 for Non -Municipals.
Limitations for Total Residual Chlorine (TRC) are based on the NC water quality standard for protection
of aquatic life (17 ug/1) and capped at 28 ug/1(acute impacts). Due to analytical issues, all TRC values
reported below 50 ug/1 are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal:
The TRC limit in the current permit was incorporated in 2007 and is based on the statewide standard for
chlorine. No changes are proposed for TRC.
Ammonia limits were set based on a wasteload allocation (WLA) conducted in December of 1991. In
1996 it was decided that the ammonia limits be set on best available technology (BAT). Ammonia has
been reviewed as a toxicant and has been found to be consistent with the BAT limits. No changes are
proposed.
Reasonable Potential AnalysisRPA) for Toxicants
If applicable, conduct RPA analysis and complete information below.
Page 5 of 12

The need for toxicant limits is based upon a demonstration of reasonable potential to exceed water quality
standards, a statistical evaluation that is conducted during every permit renewal utilizing the most recent
effluent data for each outfall. The RPA is conducted in accordance with 40 CFR 122.44 (d) (i). The NC
RPA procedure utilizes the following: 1) 95% Confidence Level/95% Probability; 2) assumption of zero
background; 3) use of/Z detection limit for "less than" values; and 4) streamflows used for dilution
consideration based on 15A NCAC 2B.0206. Effective April 6, 2016, NC began implementation of
dissolved metals criteria in the RPA process in accordance with guidance titled NPDES Implementation of
Instream Dissolved Metals Standards, dated June 10, 2016.
A reasonable potential analysis was conducted on effluent toxicant data collected between January 2019
and June 2023. Pollutants of concern included toxicants with positive detections and associated water
quality standards/criteria. Based on this analysis, the following permitting actions are proposed for this
permit:
• Effluent Limit with 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, Fluoride.
• 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: None
• POTW Effluent Pollutant Scan Review: Three effluent pollutant scans were evaluated for
additional pollutants of concern. Parameters that were detected in the scan and are regulated
under either an EPA criteria or a water quality standard were added to the RPA. Zinc, Nickel,
Chloroform and dichlorobromomethane were evaluated since they were detected and there are
criteria or standards for these parameters.
o The following parameter(s) will receive a water quality -based effluent limit (WQBEL)
with monitoring, since as part of a limited data set, two samples exceeded the allowable
discharge concentration: None
o The following parameter(s) will receive a monitor -only requirement, since as part of a
limited data set, one sample exceeded the allowable discharge concentration: None
o The following parameters will not receive a limit or monitoring, since they did not
demonstrate reasonable potential to exceed applicable water quality standards/criteria and
none of the samples exceeded the allowable concentration: Zinc, Nickel, Chloroform,
Dichlorobromomethane.
Toxicity Testing Limitations
Permit limits and monitoring requirements for Whole Effluent Toxicity (WET) have been established in
accordance with Division guidance (per WET Memo, 8/2/1999). Per WET guidance, all NPDES permits
issued to Major facilities or any facility discharging "complex" wastewater (contains anything other than
domestic waste) will contain appropriate WET limits and monitoring requirements, with several
exceptions. The State has received prior EPA approval to use an Alternative WET Test Procedure in
NPDES permits, using single concentration screening tests, with multiple dilution follow-up upon a test
failure.
Describe proposed toxicity test requirement: This is a Major POTW, and a chronic WET limit at 90%
effluent will continue on a quarterly frequency.
Page 6 of 12

Mercury Statewide TMDL Evaluation
There is a statewide TMDL for mercury approved by EPA in 2012. The TMDL target was to comply
with EPA's mercury fish tissue criteria (0.3 mg/kg) for human health protection. The TMDL established a
wasteload allocation for point sources of 37 kg/year (81 lb/year), and is applicable to municipals and
industrial facilities with known mercury discharges. Given the small contribution of mercury from point
sources (-2% of total load), the TMDL emphasizes mercury minimization plans (MMPs) for point source
control. Municipal facilities > 2 MGD and discharging quantifiable levels of mercury (>1 ng/1) will
receive an MMP requirement. Industrials are evaluated on a case -by -case basis, depending if mercury is a
pollutant of concern. Effluent limits may also be added if annual average effluent concentrations exceed
the WQBEL value (based on the NC WQS of 12 ng/1) and/or if any individual value exceeds a TBEL
value of 47 ng/l.
Table 2. Mercury Effluent Data Summary
2020
2021
2022
# of Samples
1
1
1
Annual Average Conc. n /L
NA
NA
NA
Maximum Conc., n /L
3.5
2.1
< 1
TBEL, n /L
47
WQBEL, n /L
12
Describe proposed permit actions based on mercury evaluation: Since no individual mercury sample
exceeded the TBEL, no mercury limit is required. The facility discharges < 2 MGD therefore no MMP is
required.
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation
within this permit:
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: As required by Session
Law 2018-5, Senate Bill 99, Section 13.1(r), every applicant shall submit documentation of any additional
pollutants for which there are certified methods with the permit application if their discharge is
anticipated via a Chemical Addendum to NPDES Application table. As an attachment to the permit
application, the Town informed the Division that no monitoring for additional pollutants has been
conducted (see attached chemical addendum) and therefore no additional pollutants of concern have been
identified.
To better understand the contribution of PFAS compounds from the Windsor WWTP, monitoring of
PFAS chemicals will be added to the permit at a frequency of 2/year. The frequency of 2/year was chosen
due to the lack of any downstream drinking water intake and the discharge being 100% domestic. Since
an EPA method for sampling and analyzing PFAS in wastewater is not currently available, the PFAS
sampling requirement in the Permit includes a compliance schedule which delays the effective date of this
requirement until the first full calendar quarter beginning 6 months after EPA has a final wastewater
Page 7 of 12

method in 40 CFR 136 published in the Federal Register. This date may be extended upon request and if
there are no NC -certified labs.
If applicable, describe any special actions (HQW or ORW) this receiving stream and classification shall
comply with in order to protect the designated waterbody: N/A
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:
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
If NO, provide a justification (e.g., waste stabilization pond). NA
8. Antidegradation Review (New/Expanding Discharge):
The objective of an antidegradation review is to ensure that a new or increased pollutant loading will not
degrade water quality. Permitting actions for new or expanding discharges require an antidegradation
review in accordance with 15A NCAC 213.0201. Each applicant for a new/expanding NPDES permit
must document an effort to consider non -discharge alternatives per 15A NCAC 2H.0105( c)(2). In all
cases, existing instream water uses and the level of water quality necessary to protect the existing use is
maintained and protected.
If applicable, describe the results of the antidegradation review, including the Engineering Alternatives
Analysis (EAA) and any water quality modeling results: NA
9. Antibacksliding Review:
Sections 402(o)(2) and 303(d)(4) of the CWA and federal regulations at 40 CFR 122.44(1) prohibit
backsliding of effluent limitations in NPDES permits. These provisions require effluent limitations in a
reissued permit to be as stringent as those in the previous permit, with some exceptions where limitations
may be relaxed (e.g., based on new information, increases in production may warrant less stringent TBEL
limits, or WQBELs may be less stringent based on updated RPA or dilution).
Are any effluent limitations less stringent than previous permit (YES/NO): NO
Page 8 of 12

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.
For instream monitoring, refer to Section 4.
The facility requested reduction in monitoring according to the guidance. The facility meets the criteria
outlined in the guidance. Monitoring frequency for BOD, TSS, ammonia and fecal coliform were
modified to 2/week. The existing permit requires weekly monitoring for ammonia and fecal coliform. As
specified by 15 NCAC 02B .0508 for Grade 3 WPCS the monitoring frequency for ammonia and fecal
coliform should have been 3 times per week. The reduction in monitoring guidance establishes a
minimum frequency of 2/week, therefore the minimum frequency allowed for ammonia and fecal
coliform is 2/week.
11. Electronic Reporting Requirements
The US EPA NPDES Electronic Reporting Rule was finalized on December 21, 2015. Effective
December 21, 2016, NPDES regulated facilities are required to submit Discharge Monitoring Reports
(DMRs) electronically. While NPDES regulated facilities would initially be required to submit additional
NPDES reports electronically effective December 21, 2020, EPA extended this deadline from December
21, 2020, to December 21, 2025. The current compliance date, effective January 4, 2021, was extended as
a final regulation change published in the November 2, 2020 Federal Register. This permit contains the
requirements for electronic reporting, consistent with Federal requirements.
12.Summary of Proposed Permitting Actions:
Table 3. Current Permit Conditions and Proposed Changes 1.15 MGD
Parameter
Current Permit
Proposed Change
Basis for Condition/Change
Flow
MA 1.15 MGD
No change
15A NCAC 2B .0505
BOD5
Summer:
Monitoring frequency
WQBEL. Based on protection of DO
MA 5 mg/1
changed to 2/week
standard. 15A NCAC 2B.0200
WA 7.5 mg/1
Winter:
Reduce Monitoring Frequency for
MA 10 mg/1
Exceptional Facilities Guidance
WA 15 m /l
Page 9 of 12

Monitor and report
3/week
NH3-N
Summer:
Monitoring frequency
WQBEL. Based on protection of
MA 1.0 mg/l
changed to 2/week
State WQ criteria. 15A NCAC
WA 3.0 mg/1
2B.0200
Winter:
Monitoring frequency based on 15
MA 2.0 mg/1
NCAC 02B .0508 should be 3/week,
WA 6.0 mg/1
minimum frequency as per
Monitor and report
Reduce Monitoring Frequency for
weekly
Exceptional Facilities Guidance is
2/week.
TSS
MA 30 mg/l
Monitoring frequency
TBEL. Secondary treatment
WA 45 mg/1
changed to 2/week
standards/40 CFR 133 / 15A NCAC
Monitor and report
2B .0406
3/week
Reduce Monitoring Frequency for
Exceptional Facilities Guidance
Fecal coliform
MA 200 /100ml
Monitoring frequency
WQBEL. State WQ standard, 15A
WA 400 /100ml
changed to 2/week
NCAC 2B .0200
Monitor and report
Monitoring frequency based on 15
weekly
NCAC 02B .0508 should be 3/week,
minimum frequency as per
Reduce Monitoring Frequency for
Exceptional Facilities Guidance is
2/week.
DO
> 5 mg/1
No change
WQBEL. State WQ standard, 15A
Monitor and report
NCAC 2B .0200
3/week
pH
6 — 9 SU
No change
WQBEL. State WQ standard, 15A
Monitor and report
NCAC 2B .0200
3/week
Total Residual
DM 17 ug/L
No change
WQBEL. 2023 WLA review.
Chlorine
Monitor and report
Surface Water Monitoring, 15A
3/Week
NCAC 2B. 0500
TKN
No requirement
Monitor and Report
For calculation of TN
quarterly
Nitrate + Nitrite
No requirement
Monitor and Report
For calculation of TN
quarterly
Total Nitrogen
Monitor and Report
No change
Surface Water Monitoring, 15A
quarterly
NCAC 2B. 0500
Total Phosphorus
Monitor and Report
No change
Surface Water Monitoring, 15A
quarterly
NCAC 2B. 0500
Total Copper
MA 13.8 ug/1
MA 11.9 ug/1
RPA
DM 19.4 ug/1
DM 16.5 ug/1
WQBEL. State WQ standard, 15A
Monitor monthly
Monitor monthly
NCAC 2B .0200
Total Fluoride
MA 1.8 ug/1
No changes
RPA
DM 5.4 ug/1
WQBEL. State WQ standard, 15A
Monitor monthly
NCAC 2B .0200
Page 10 of 12

Total Hardness
Quarterly effluent
No change
Hardness -dependent dissolved
monitoring
metals water quality standards
approved in 2016 — no upstream
hardness required due to 0 cfs 7Q10
Toxicity Test
Chronic limit, 90%
No change
WQBEL. No toxics in toxic
effluent
amounts. 15A NCAC 213.0200 and
15A NCAC 213.0500
Effluent Pollutant
Three times per permit
Three times per
40 CFR 122
Scan
cycle (2020, 2021, 2022)
permit cycle (2025,
2026, 2027)
Electronic
Electronic reporting
No change
In accordance with EPA Electronic
Reporting
special condition
Reporting Rule 2015.
PFAS Monitoring
No requirement
2/year monitoring
Evaluation of PFAS contribution;
Implementation delayed until after
EPA certified method becomes
available.
MGD — Million gallons per day, MA - Monthly Average, WA — Weekly Average, DM — Daily Max
13. Public Notice Schedule:
Permit to Public Notice: 1 l/15/2023
Per 15A NCAC 2H .0109 & .0111, The Division will receive comments for a period of 30 days following
the publication date of the public notice. Any request for a public hearing shall be submitted to the
Director within the 30 days comment period indicating the interest of the party filing such request and the
reasons why a hearing is warranted.
14. NPDES Division Contact
If you have any questions regarding any of the above information or on the attached permit, please
contact Teresa Rodriguez via email at [e-mail].
15. Fact Sheet Addendum (if applicable):
Were there any changes made since the Draft Permit was public noticed (Yes/No):
If Yes, list changes and their basis below:
16. Fact Sheet Attachments (if applicable):
• RPA Spreadsheet Summary
• NPDES Implementation of Instream Dissolved Metals Standards — Freshwater Standards
or Saltwater Standards
• NH3/TRC WLA Calculations
Page 11 of 12

• BOD & TSS Removal Rate Calculations
• Mercury TMDL Calculations
• WET Testing and Self -Monitoring Summary
• Water Compliance Inspection Report
• Applicable special correspondences
Page 12 of 12

Town of Windsor
NCO026751 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM DATA POINTS = 58
Qw (MGD) = 1.1500 WWTP/WTP Class: Windsor WWTP/Class 3
1Q10S (cfs) = 0.00 IWC% @ 1Q10S = 100
7Q10S (cfs) = 0.00 IWC% @ 7Q10S = 100
7Q10W (cfs) = 0.00 IWC% @ 7Q10W = 100
30Q2 (cfs) = 0.00 IWC% @ 30Q2 = 100
Avg. Stream Flow, QA (cfs) = 4.50 IW%C @ QA = 28.37246319
Receiving Stream: UT to Cashie River HUC 3010107 Stream Class: C
Outfall 001
Qw = 1.15 MGD
COMBINED HARDNESS (mg/L)
Acute = 40.47 mg/L
Chronic = 40.47 mg/L
PARAMETER
NC STANDARDS OR EPA CRITERIA
F
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
TYPE
J
a
Applied
Chronic Acute
ri # Det. Max Pred Cw Allowable Cw
Standard
Acute (FW): 340.0
Arsenic
C
150 FW 340
ug/L
0 0
N/A
Chronic (FW): 150.0
Arsenic
C
10 HH/WS
ug/L
Chronic (HH): 35.2
Acute: 65.00
Beryllium
NC
6.5 FW 65
ug/L
0 0
N/A
_ _ _ _ _ --
---------------------------
Chronic:---- 6.50
Acute: 4.933
Cadmium
NC
0.8491 FW 4.9330
ug/L
0 0
N/A
_ _ _ _ _ _ _ _
Chronic: 0.849
Acute: NO WQS
Chlorides
NC
230 FW
mg/L
0 0
N/A
_ _ _ _
Chronic: — — 230_.0------------------------
— — —
Acute: NO WQS
Chlorinated Phenolic Compounds
NC
I A
ug/L
0 0
N/A
_ _ _ --
---------------------------
Chronic:---- 1-0
Acute: NO WQS
Total Phenolic Compounds
NC
300 A
ug/L
0 0
N/A
_ _ _ _ _ _
-----300.0--
---------------------------
Chronic:
Acute: 1,342.8
Chromium III
NC
174.6751 FW 1342.8337
ug/I.
0 0
N/A
_ _ _
Chronic: — — _ 174_.7--
---------------------------
Acute: 16.0
Chromium VI
NC
11 FW 16
µg/L
0 0
N/A
_ _ _ _ _
Chronic:---- 11.0 --
---------------------------
Chromium, Total
NC
µg/I.
0 0
N/A
Acute: 16.49
RP shown - apply Monthly Monitoring with Limit
Copper
NC
11.8938 FW 16.4868
ug/L
58 26
28.00
_ _ _ - - _ _ _ _
- - - - - - - - - - - - -
_
Chronic: 11 89
NCO026751 RPA Sept 23, rpa
Page 1 of 2 10/17/2023

Town of Windsor - Outfall 001
NCO026751 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 1.15 MGD
12 values > Allowable Cw
Acute: 22.0
Cyanide
NC
5 FW 22
10
ug/L
0 0
N/A
_ _ _ _ _
Chronic:---- 5.0 --
— - — - — - — - — - — - — - —
Acute: NO WQS
RP shown - apply Monthly Monitoring with Limit
Fluoride
NC
1800 FW
ug/L
56 56
2,100.0
_ _ _ _ ----_ _
Chronic:-1,800.0—
---------------------------
6 values > Allowable Cw
Acute: 129.523
Lead
NC
5.0473 FW 129.5231
ug/L
0 0
N/A
_ _ _
Chronic: _—— 5.047-_—------------——
Acute: NO WQS
Mercury
NC
12 FW
0.5
ng/L
0 0
N/A
_ _ _ _ _ _ _ _
_ _
Chronic: 12.0
Acute: NO WQS
Molybdenum
NC
2000 HH
ug/l.
0 0
N/A
----2,000.0—
Chronic:
Acute (FW): (FW): 503.8
No RP, No monitoring required - Limited Dataset with
Nickel
NC
55.9618 FW 503.8463
µg/L
all detected levels < 50% of Cw
3 1
9.0
Chronic (FW): 56.0
Note: n 5 9
C.V. (default)
No value > Allowable Cw
Nickel
NC
25.0000 WS
µg/L
Limited data set
Chronic (WS): 25.0
No value > Allowable Cw
Acute: 56.0
Selenium
NC
5 FW 56
ug/L
0 0
N/A
_ _ _ _ _
Chronic:---- 5.0----------------
Acute: 0.679
Silver
NC
0.06 FW 0.6787
ug/L
0 0
N/A
_ _ _ _
Chronic: — — 0.06_0--
---------------------------
Acute: 189.1
No RP, No monitoring required - Limited Dataset with
Zinc
NC
190.6102 FW 189.0636
ug/L
3 3
111.0
all detected levels < 50% of Cw
Note: n 5 9
C.V. (default)
Chronic: 190.6
Limited data set
No value > Allowable Cw
Acute: NO WQS
No RP, Predicted Max < 50% of Allowable Cw - No
Chloroform
NC
2000 FW
ug/l
3 1
18.09000
Monitoring required
Note: n 5 9
C.V. (default)
Chronic: 2000.00000
Limited data set
No value > Allowable Cw
Acute: NO WQS
No RP, No monitoring required - Limited Dataset with
Dichlorobromomethane
C
17 HH
ug/l
3 1
19.38000
all detected levels < 50% of Cw
Note: n <9
C.V. (default)
Chronic: 59.91725
-------------------------
Limited data set
No value > Allowable Cw
NCO026751 RPA Sept 23, rpa
Page 2 of 2 10/17/2023

Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM DATA POINTS = 58
Table 1. Project Information
Facility Name
WWTP/WTP Class
NPDES Permit
Outfal I
Flow, Qw (MGD)
Receiving Stream
HUC Number
Stream Class
❑ CHECK IF HQW OR ORW WQS
Town of Windsor
Windsor WWTP/Class 3
NCO026751
001
1.150
UT to Cashie River
3010107
C
❑ Apply WS Hardness WQC
7Q10s (cfs)
7Q10w (cfs)
30Q2 (cfs)
QA (cfs)
1 Q10s (cfs)
0.00
0.00
0.00
4.50
0 jW
_Effluent Hardness _ _ _ _
Upstream Hardness
-I-------------------
_Combined Hardness Chronic_I_-------40.47mg/L
Combined Hardness Acute
40.47 mg/L (Avg)
NO UPSTREAM HARDNESS DATA
40.47 mg/L
- - - - - - - - - - - - - - - -
Data Source(s)
❑ CHECK TO APPLY MODEL
Follow directions for data entry. In some cases a
comment menu list the available choices or a
dropdown menu will provide a list you may select
from. Error message occur if data entry does not
meet input criteria.
REQUIRED DATA ENTRY
Par01
Par02
Par03
Par04
Partly
Par06■
Par07
Partl8
Par09
Par10
Par11
Par12
Par13
Par14
Par15
Par16
Par17
Par18
Par19
Par20
Par21
Par22
Par23
Par24
Par25
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
0.8491
FW
4.9330
ug/L
Chlorides
Aquatic Life
NC
230
FW
mg/L
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
174.6751
FW
1342.8337
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
11.8938
FW
16.4868
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
5.0473
FW
129.5231
ug/L
Mercury
Aquatic Life
NC
12
FW
0.5
ng/L
Molybdenum
Human Health
NC
2000
HH
ug/L
Nickel
Aquatic Life
NC
55.9618
FW
503.8463
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
0.6787
ug/L
Zinc
Aquatic Life
NC
190.6102
FW
189.0636
ug/L
Chloroform
Aquatic Life
NC
2000
FW
ug/I
Dichlorobromomethane
Human Health
C
17
HH
ug/I
NCO026751 RPA Sept 23, input
10/ 17/2023

H1
Date Data
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 Use "PASTE SPECIAL
Effluent Hardness Values" then "COPY". Upstream Hardness Values" then "COPY".
Maximum data points Maximum data points
= 58 1 = 58
BDL=1/2DL
Results
Date Data
BDL=1/2DL Results
47 47
Std Dev.
6.3158
1
Std Dev.
NO DATA
35 35
Mean
40.4706
2
Mean
NO DATA
39 39
C.V.
0.1561
3
C.V.
NO DATA
34 34
n
17
4
n
0
38 38
10th Per value
33.20 mg/L
5
10th Per value
NO DATA mg/L
42 42
Average Value
40.47 mg/L
6
Average ValueVESS
DATA mg/L
38 38
Max. Value
53.00 mg/L
7
Max. Value
NO DATA mg/L
36 36
8
42 42
9
42 42
10
37 37
11
42 42
12
48 48
13
51 51
14
32 32
15
53 53
16
32 32
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
NCO026751 RPA Sept 23, data
1 10/17/2023

REASONABLE POTENTIAL ANALYSIS
Par01 & Par02
Use"PASTE SPECIAL
Arsenic
Values" then "COPY"
Maximum data points
= 58
Date Data
BDL=1/2DL Results
1
Std Dev.
NO DATA
2
Mean
NO DATA
3
C.V.
NO DATA
4
n
0
5
6
Mult Factor =
N/A
7
Max. Value
N/A ug/L
8
Max. Pred Cw
N/A ug/L
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
NCO026751 RPA Sept 23, data
- 2 - 10/17/2023

REASONABLE POTENTIAL ANALYSIS
Par03
Par04
Use "PASTE SPECIAL
Use "PASTE SPECIAL
Beryllium
Values" men "COPY".
Cadmium
Values" then "COPY".
I
Maximum data points
Maximum data points
= 58
= 58
Date Data
BDL=1/2DL Results
Date Data
BDL=1/2DL Results
1
Std Dev.
NO DATA
1
Std Dev.
NO DATA
2
Mean
NO DATA
2
Mean
NO DATA
3
C.V.
NO DATA
3
C.V.
NO DATA
4
n
0
4
n
0
5
5
6
Mult Factor =
N/A
6
Mult Factor =
N/A
7
Max. Value
N/A ug/L
7
Max. Value
N/A ug/L
8
Max. Pred Cw
N/A ug/L
8
Max. Pred Cw
N/A ug/L
9
9
10
10
11
11
12
12
13
13
14
14
15
15
16
16
17
17
18
18
19
19
20
20
21
21
22
22
23
23
24
24
25
25
26
26
27
27
28
28
29
29
30
30
31
31
32
32
33
33
34
34
35
35
36
36
37
37
38
38
39
39
40
40
41
41
42
42
43
43
44
44
45
45
46
46
47
47
48
48
49
49
50
50
51
51
52
52
53
53
54
54
55
55
56
56
57
57
58
58
NCO026751 RPA Sept 23, data
-3- 10/17/2023

REASONABLE POTENTIAL ANALYSIS
Par05
Chlorides
Use "PASTE SPECIAL-
Values' then "COPY".
Par06
Use "PASTE SF
Chlorinated Phenolic Compounds
Values"then"<
Maximum data points =
Maximum data
= 58
58
Date Data
BDL=1/2DL Results
Date Data BDL=1/2DL Results
1
Std Dev.
NO DATA
1
Std Dev.
NO DATA
2
Mean
NO DATA
2
Mean
NO DATA
3
C.V.
NO DATA
3
C.V.
NO DATA
4
n
0
4
n
0
5
5
6
Mult Factor =
N/A
6
Mult Factor =
N/A
7
Max. Value
N/A mg/L
7
Max. Value
N/A
8
Max. Pred Cw
N/A mg/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
NCO026751 RPA Sept 23, data
-4- 10/17/2023

REASONABLE POTENTIAL ANALYSIS
'ECIAL
Par07
°PY"
Total Phenolic Compounds
points
Date
Data BDL=1/2DL Results
1
Std Dev.
2
Mean
3
C.V.
4
n
5
6
Mult Factor =
ug/L
7
Max. Value
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
Par08
Use "PASTE SPECIAL
Values " then "COPY".
Chromium III
Maximum data points
= 58
Date
Data BDL=1/2DL Results
NO DATA
1
Std Dev.
NO DATA
2
Mean
NO DATA
3
C.V.
0
4
n
5
N/A
6
Mult Factor =
N/A ug/L
7
Max. Value
N/A 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 SF
Values" then 'Y
Maximum data
= 58
NO DATA
NO DATA
NO DATA
0
N/A
N/A
N/A
NCO026751 RPA Sept 23, data
-5- 10/17/2023

REASONABLE POTENTIAL ANALYSIS
'EC"T- Par09
:OPY.
points
Date
Data
1
2
3
4
5
6
pg/L
7
pg/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
NO DATA
1
Std Dev.
NO DATA
2
Mean
NO DATA
3
C.V.
0
4
n
5
N/A
6
Mult Factor =
N/A pg/L
7
Max. Value
N/A pg/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 SF
Values" then 'T
Maximum data
= 58
NO DATA
NO DATA
NO DATA
0
N/A
N/A
N/A
-6-
NCO026751 RPA Sept 23, data
10/17/2023

REASONABLE POTENTIAL ANALYSIS
IECIAL Pall
:OPY . Copper
opper
pg/L
pg/L
Date
Data
BDL=1/2DL
Results
1
04/22/19
10
10
Std Dev.
2
05/07/19
12
12
Mean
3
05/27/19
10
10
C.V.
4
06/04/19
<
24
12
n
5
06/19/19
10
10
6
07/04/19
<
10
5
Mult Factor =
7
07/09/19
10
10
Max. Value
8
08/06/19
<
10
5
Max. Pred Cw
9
09/03/19
<
10
5
10
10/01/19
<
10
5
11
10/21/19
<
10
5
12
10/28/19
<
10
5
13
11/06/19
<
10
5
14
11/18/19
<
10
5
15
11/25/19
<
10
5
16
11/28/19
<
10
5
17
11/29/19
<
15
7.5
18
12/02/19
<
14
7
19
12/24/19
<
10
5
20
12/25/19
10
10
21
12/26/19
10
10
22
12/31/19
<
14
7
23
01 /06/20
<
10
5
24
02/03/20
<
10
5
25
03/02/20
10
10
26
05/05/20
<
10
5
27
05/25/20
<
10
5
28
06/02/20
<
10
5
29
07/03/20
<
15
7.5
30
07/07/20
<
14
7
31
08/11/20
<
10
5
32
09/01 /20
14
14
33
09/07/20
10
10
34
11 /26/20
<
18
9
35
11 /27/20
10
10
36
12/01 /20
<
10
5
37
12/24/20
10
10
38
12/25/20
<
56
28
39
12/28/20
<
19
9.5
40
01/01/21
<
13
6.5
41
01/05/21
11
11
42
02/02/21
10
10
43
03/02/21
10
10
44
04/06/21
12
12
45
05/04/21
<
20
10
46
06/02/21
<
15
7.5
47
07/06/21
13
13
48
08/03/21
17
17
49
09/07/21
19
19
50
09/27/21
17
17
51
10/12/21
11
11
52
10/27/21
13
13
53
11 /09/21
10
10
54
11/11/21
10
10
55
11 /25/21
13
13
56
11 /26/21
<
15
7.5
57
12/07/21
<
13
6.5
58
12/23/21
13
13
Use "PASTE SPECIAL Par12
Jalues" then "COPY".
Maximum data points
= 58
9.0948
0.4717
58
1.00
28.00 ug/L
28.00 ug/L
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Use "PASTE SF
Cyanide
Values" then'T
Maximum data
= 58
Date Data BDL=1/2DL Results
Std Dev.
NO DATA
Mean
NO DATA
C.V.
NO DATA
n
0
Mult Factor =
N/A
Max. Value
N/A
Max. Pred Cw
N/A
NCO026751 RPA Sept 23, data
-7- 10/17/2023

REASONABLE POTENTIAL ANALYSIS
,ECIAL Par13
°OPr� points Fluoride
ug/L
ug/L
Date
Data
BDL=1/2DL
Results
1
3/5/2019
1100
1100
Std Dev.
2
4/3/2019
1500
1500
Mean
3
5/7/2019
1600
1600
C.V.
4
6/4/2019
2100
2100
n
5
6/19/2019
1400
1400
6
7/9/2019
1800
1800
Mult Factor =
7
8/6/2019
1000
1000
Max. Value
8
9/3/2019
1900
1900
Max. Pred Cw
9
9/9/2019
1100
1100
10
10/1 /2019
1700
1700
11
11 /6/2019
1600
1600
12
12/2/2019
1500
1500
13
1 /6/2020
1400
1400
14
2/3/2020
1300
1300
15
3/2/2020
1300
1300
16
4/7/2020
1400
1400
17
5/5/2020
1300
1300
18
6/2/2020
1100
1100
19
7/7/2020
1700
1700
20
8/11/2020
1400
1400
21
9/1 /2020
1700
1700
22
10/6/2020
1800
1800
23
11 /2/2020
1800
1800
24
12/1 /2020
1300
1300
25
1 /5/2021
630
630
26
2/2/2021
540
540
27
3/2/2021
1000
1000
28
4/6/2021
1500
1500
29
5/4/2021
1700
1700
30
6/2/2021
1700
1700
31
7/6/2021
1400
1400
32
8/3/2021
1800
1800
33
9/7/2021
2000
2000
34
9/27/2021
1810
1810
35
10/ 12/2021
1800
1800
36
11 /9/2021
1900
1900
37
12/7/2021
1600
1600
38
1 /3/2022
1400
1400
39
2/1/2022
1500
1500
40
3/1/2022
1400
1400
41
4/6/2022
1800
1800
42
5/3/2022
1900
1900
43
5/17/2022
1600
1600
44
6/6/2022
1600
1600
45
7/4/2022
1700
1700
46
8/1/2022
1700
1700
47
9/6/2022
1800
1800
48
10/3/2022
1200
1200
49
11 /8/2022
1100
1100
50
12/6/2022
1120
1120
51
1 /10/2023
1400
1400
52
2/1/2023
830
830
53
3/7/2023
1500
1500
54
4/5/2023
1400
1400
55
5/8/2023
1300
1300
56
6/5/2023
1700
1700
57
58
Use "PASTE SPECIAL Par14
Jalues.'then "COPY".
Maximum data points
= 58
1484.4643
0.2218
56
1.00
2100.0 ug/L
2100.0 ug/L
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Use "PASTE SF
Lead
Values" then 'Y
Maximum data
= 58
Date BDL=1/2DL Results
Std Dev.
NO DATA
Mean
NO DATA
C.V.
NO DATA
n
0
Mult Factor =
N/A
Max. Value
N/A
Max. Pred Cw
N/A
NCO026751 RPA Sept 23, data
-8- 10/17/2023

REASONABLE POTENTIAL ANALYSIS
Par15
Par16
Mercury
Use "PASTE SPECIAL
Values" then "COPY" .
Use "PASTE SF
Molybdenum
Values" then 'T
Maximum data points
=58
Maximum data
=58
Date Data
BDL=1/2DL Results
Date
Data BDL=1/2DL Results
1
Std Dev.
NO DATA
1
Std Dev.
NO DATA
2
Mean
NO DATA
2
Mean
NO DATA
3
C.V.
NO DATA
3
C.V.
NO DATA
4
n
0
4
n
0
5
5
6
Mult Factor =
N/A
6
Mult Factor =
N/A
ug/L
7
Max. Value
N/A ng/L
7
Max. Value
N/A
ug/L
8
Max. Pred Cw
N/A ng/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
NCO026751 RPA Sept 23, data
-9- 10/17/2023

REASONABLE POTENTIAL ANALYSIS
ug/L
ug/L
Par17 & Par18
Nickel
Use "PASTE SPECIAL
Values" then "COPY".
Par19
Selenium
Maximum data points
= 58
Date
Data BDL=1/2DL
Results
Date Data
BDL=1/2DL Results
1
< 5 2.5
Std Dev.
0.2887
1
Std Dev.
2
3 3
Mean
2.6667
2
Mean
3
< 5 2.5
C.V. (default)
0.6000
3
C.V.
4
n
3
4
n
5
5
6
Mult Factor =
3.00
6
Mult Factor =
7
Max. Value
3.0 Ng/L
7
Max. Value
8
Max. Pred Cw
9.0 Ng/L
8
Max. Pred Cw
9
9
10
10
11
11
12
12
13
13
14
14
15
15
16
16
17
17
18
18
19
19
20
20
21
21
22
22
23
23
24
24
25
25
26
26
27
27
28
28
29
29
30
30
31
31
32
32
33
33
34
34
35
35
36
36
37
37
38
38
39
39
40
40
41
41
42
42
43
43
44
44
45
45
46
46
47
47
48
48
49
49
50
50
51
51
52
52
53
53
54
54
55
55
56
56
57
57
58
58
NCO026751 RPA Sept 23, data
-10- 10/17/2023

REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par20
Values" then "COPY" .
Maximum data points
= 58
NO DATA 1
NO DATA 2
NO DATA 3
0 4
5
N/A 6
N/A ug/L 7
N/A 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
Silver
Date Data BDL=1/2DL Results
Std Dev.
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Fred Cw
Use "PASTE SPECIAL Par21
Values" then "COPY" .
Maximum data points
= 58
NO DATA
NO DATA
0
N/A
N/A ug/L
N/A ug/L
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Zinc
Date Data BDL=1/2DL Results
37 37 Std Dev.
34 34 Mean
28 28 C.V. (default)
n
Mult Factor =
Max. Value
Max. Pred Cw
-11-
NCO026751 RPA Sept 23, data
10/17/2023

REASONABLE POTENTIAL ANALYSIS
Par22
Par23
Use "PASTE SPECIAL
Use "PASTE SPECIAL
DICFIIOCObC01110111@t
Values" then "COPY" .
then "COPY".
Chloroform
Maximum data points
Maximum data points
Maximum
= 58
= 58
Date
1
Data BDL=1/2DL
6.03 6.03
Results
Std Dev.
2.0380
Date
1
Data BDL=1/2DL
4.5826
33.0000
2
< 5 2.5
Mean
3.6767
2
0.6000
3
< 5 2.5
C.V. (default)
0.6000
3
< 5 2.5
3
4
n
3
4
< 5 2.5
5
5
6.46 6.46
3.00
6
Mult Factor =
3.00
6
37.0 ug/L
7
Max. Value
6.030000 ug/I
7
111.0 ug/L
8
Max. Pred Cw
18.090000 ug/I
8
9
9
10
10
11
11
12
12
13
13
14
14
15
15
16
16
17
17
18
18
19
19
20
20
21
21
22
22
23
23
24
24
25
25
26
26
27
27
28
28
29
29
30
30
31
31
32
32
33
33
34
34
35
35
36
36
37
37
38
38
39
39
40
40
41
41
42
42
43
43
44
44
45
45
46
46
47
47
48
48
49
49
50
50
51
51
52
52
53
53
54
54
55
55
56
56
57
57
58
58
NCO026751 RPA Sept 23, data
-12- 10/17/2023

REASONABLE POTENTIAL ANALYSIS
Use"PASTE SPECIAL Par24
hane Values" then "COPY".
Maximum data points
= 58
Results
Std Dev.
2.2863
Mean
3.8200
C.V. (default)
0.6000
n
3
Mult Factor =
3.00
Max. Value
6.460000 ug/I
Max. Pred Cw
19.380000 ug/I
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
0
Date Data BDL=1/2DL Results
Std Dev.
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Pred Cw
Use"PASTE SPECIAL Par25
Jalues" 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
0
Date Data BDL=1/2DL
-13-
NCO026751 RPA Sept 23, data
10/17/2023

REASONABLE POTENTIAL ANALYSIS
Use"PASTE SPECIAL
Values" then "COPY"
Maximum data points
= 58
Results
Std Dev.
NO DATA
Mean
NO DATA
C.V.
NO DATA
Mult Factor = N/A
Max. Value N/A
Max. Fred Cw N/A
-14-
NCO026751 RPA Sept 23, data
10/17/2023

Date: 11/1/2023
Enter data onto "Table 1" under the Input Sheet and enter
"Effluent Hardness" under the Data Sheet.
In accordance with 40 CFR 122.45 (c ), permits are, have and
must be written as total metals.
This calculator has been inserted into the RPA to calculate
Total Metal allowable allocations once Table 1 has been
completed (Input Sheet) and Effluent hardness has been
entered (Data Sheet).
1) Following the spreadsheet from left to right. First
the allowable allocations for the dissolved metals will
appear for all the metals listed once Table 1 is complete
and effluent hardness entered. Use a default value of 25
mg/L if no hardness data is available. Second
the Dissolved Metal allocations are divided by the
Translators to determine the Total Metals that can be
allocated to the Permittee. These Total Metals values are
automatically inserted into Table 2 and are the allowable
Total Metal allocations determined for the Permittee prior
to allowing for dilution. See Input sheet Table 2. The final
acute and chronic values shown under the RPA sheet are
the Total Metal values listed in Table 2 divided by the
acute and chronic IWC, respectively.
2) The Translators used in the freshwater RPA are the
Partition Coefficients published by US EPA in 1984. They
are TSS dependent equations and can be found listed with
the WQS hardness dependent equations under the sheet
labeled Equations. A fixed TSS value of 10 mg/L is used to
calculate the Translator values.
3) Pretreatment Facilities — PERCS will need a copy of the
Dissolved to Total Metal Calculator spreadsheet and the
RPA sheet along with the Final Permit. Pretreatment
Facilities are required to renew their Headwords Analysis
after renewal of their permits. Since all their metal
allocations are likely to change PERCS needs to see any
new metal permit limits and the allowable allocations for
the dissolved metals to assess Maximum Allowable
Headworks Loading (MAHL) numbers for each metal based
on the Combined Hardness values used in the permit
writers RPA calculations.
4) For Cadmium, Lead, Nickel, Chromium and Beryllium, if al
the effluent sampling data for the last three to five years
shows the pollutant at concentrations less than the
Practical Quantitative Level (PQL), it is not likely a limit or
monitoring will be put in the permit. However, if the
estimated NPDES permit limit is less than the Practical
Quantitative Limit (particularly, Cadmium and Lead) and
the pollutant is believed to be present, to assess
compliance with the new standards and for future permit
limit development, monitoring for the pollutant will be
required. If the facility is monitoring for the pollutant in its
Pretreatment LTMP, no monitoring is needed in the
V: Town of Windsor Outfall 001
PERMIT: NCO026751 Dissolved to Total Metal Calculator
In accordance with Federal Regulations, permit limitations must be written as Total Metals per 40 CFR 122.45(c)
Stream
Receiving
Sheam summ
1Q10
Solids
Flay Limit -Fixed Value
Hardness
chronic
Hardness
Acute
7Q10 (CFS)
Q10 (MGD)
MGD
MGD (mgsL)
(mgfL)
(mgfL)
0.0000
0.0000
0.0000
1.1500 1 10
40.4]i
40.471
Dissolved Metals Criteria
US EPA
Total Metal criteria Total Metal=
COMMENTS (identify par:
PARAMETER
after applying hartlness
equation
Translators -using
Default Partition
Oissolvetl Metal *Translator
Chronic Acute
Coefficients
Chronic I Acute
INi - WS streams (t) I I 1 25 N/AI
(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 of total —weable 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 pg/L which is Total Recoverable metal standard.
Instream Insiream Upstream Effluent
Wastewater Wastewater Hardness
concert.— Concentration Hartlness Average
(Chronic) (Acute) Average (mg/L) (myL)
EFF Hard Avg (mg/L) = 40.47059
ACAH 40.47059
ACCH 40.47059

Permit No. NCO0226751
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/l
(Dissolved)
Acute SW, µg/1
(Dissolved)
Chronic SW, µg/1
(Dissolved)
Arsenic
340
150
69
36
Beryllium
65
6.5
---
---
Cadmium
Calculation
Calculation
40
8.8
Chromium III
Calculation
Calculation
---
---
Chromium VI
16
11
1100
50
Copper
Calculation
Calculation
4.8
3.1
Lead
Calculation
Calculation
210
8.1
Nickel
Calculation
Calculation
74
8.2
Silver
Calculation
0.06
1.9
0.1
Zinc
Calculation
Calculation
90
81
Table 1 Notes:
1. FW= Freshwater, SW= Saltwater
2. Calculation = Hardness dependent standard
3. Only the aquatic life standards listed above are expressed in dissolved form. Aquatic life
standards for Mercury and selenium are still expressed as Total Recoverable Metals due to
bioaccumulative concerns (as are all human health standards for all metals). It is still necessary
to evaluate total recoverable aquatic life and human health standards listed in 15A NCAC
2B.0200 (e.g., arsenic at 10 µg/1 for human health protection; cyanide at 5 µg/L and fluoride at
1.8 mg/L for aquatic life protection).
Table 2. Dissolved Freshwater Standards for Hardness -Dependent Metals
The Water Effects Ratio (WER) is equal to one unless determined otherwise under 15A
NCAC 02B .0211 Subparagraph (11)(d)
Metal
NC Dissolved Standard, µg/I
Cadmium, Acute
WER* 11. 136672-[ln hardness] (0.041838)} e^{0.9151 [In hardness] -3.14851
Cadmium, Acute Trout waters
WER* 11. 136672-[ln hardness] (0.041838)} e^{0.9151[ln hardness]-3.6236}
Cadmium, Chronic
WER* 11. 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 e^{0.9422[ln hardness]-1.7001
Copper, Chronic
WER*0.960 e^{0.8545[ln hardness]-1.702}
Lead, Acute
WER*{1.46203-[ln hardness](0.145712)} • e^{1.273[In hardness]-1.460}
Lead, Chronic
WER*{1.46203-[ln hardness](0.145712)) • e^{1.273[In hardness]-4.705}
Nickel, Acute
WER*0.998 eA10.8460[ln hardness]+2.255}
Nickel, Chronic
WER*0.997 e^{0.8460[ln hardness]+0.0584}
Page 1 of 4

Permit No. NCO0226751
Silver, Acute
WER*0.85 • e^{1.72[ln hardness]-6.59}
Silver, Chronic
Not applicable
Zinc, Acute
WER*0.978 eA f O.8473[ln hardness]+0.884}
Zinc, Chronic
WER*0.986 eA f O.8473[ln hardness]+0.884}
General Information on the Reasonable Potential Analysis (RPA)
The RPA process itself did not change as the result of the new metals standards. However, application of
the dissolved and hardness -dependent standards requires additional consideration in order to establish the
numeric standard for each metal of concern of each individual discharge.
The hardness -based standards require some knowledge of the effluent and instream (upstream) hardness
and so must be calculated case -by -case for each discharge.
Metals limits must be expressed as `total recoverable' metals in accordance with 40 CFR 122.45(c). The
discharge -specific standards must be converted to the equivalent total values for use in the RPA
calculations. We will generally rely on default translator values developed for each metal (more on that
below), but it is also possible to consider case -specific translators developed in accordance with
established methodology.
RPA Permitting Guidance/WOBELs for Hardness -Dependent Metals - Freshwater
The RPA is designed to predict the maximum likely effluent concentrations for each metal of concern,
based on recent effluent data, and calculate the allowable effluent concentrations, based on applicable
standards and the critical low -flow values for the receiving stream.
If the maximum predicted value is greater than the maximum allowed value (chronic or acute), the
discharge has reasonable potential to exceed the standard, which warrants a permit limit in most cases. If
monitoring for a particular pollutant indicates that the pollutant is not present (i.e. consistently below
detection level), then the Division may remove the monitoring requirement in the reissued permit.
To perform a RPA on the Freshwater hardness -dependent metals the Permit Writer compiles the
following information:
• Critical low flow of the receiving stream, 7Q10 (the spreadsheet automatically calculates
the 1 Q 10 using the formula 1 Q 10 = 0.843 (s7Q 10, cfs) 0.993
• Effluent hardness and upstream hardness, site -specific data is preferred
• Permitted flow
• Receiving stream classification
2. In order to establish the numeric standard for each hardness -dependent metal of concern and for
each individual discharge, the Permit Writer must first determine what effluent and instream
(upstream) hardness values to use in the equations.
The permit writer reviews DMR's, Effluent Pollutant Scans, and Toxicity Test results for any
hardness data and contacts the Permittee to see if any additional data is available for instream
hardness values, upstream of the discharge.
If no hardness data is available, the permit writer may choose to do an initial evaluation using a
default hardness of 25 mg/L (CaCO3 or (Ca + Mg)). Minimum and maximum limits on the
hardness value used for water quality calculations are 25 mg/L and 400 mg/L, respectively.
If the use of a default hardness value results in a hardness -dependent metal showing reasonable
potential, the permit writer contacts the Permittee and requests 5 site -specific effluent and
upstream hardness samples over a period of one week. The RPA is rerun using the new data.
Page 2 of 4

Permit No. NCO0226751
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) + (s7Q 10, cfs *Avg. Upstream Hardness, mg/L)
(Permitted Flow, cfs + s7Q10, cfs)
The Combined Hardness for acute is the same but the calculation uses the IQ 10 flow.
3. The permit writer converts the numeric standard for each metal of concern to a total recoverable
metal, using the EPA Default Partition Coefficients (DPCs) or site -specific translators, if any
have been developed using federally approved methodology.
EPA default partition coefficients or the "Fraction Dissolved" converts the value for
dissolved metal at laboratory conditions to total recoverable metal at in -stream
ambient conditions. This factor is calculated using the linear partition coefficients
found in The Metals Translator: Guidance for Calculating a Total Recoverable
Permit Limit from a Dissolved Criterion (EPA 823-B-96-007, June 1996) and the
equation:
Cdiss = 1
Ctotal 1 + f [Kpo] [ss(I+a)] [10-6] }
Where:
ss = in -stream suspended solids concentration [mg/1], minimum of 10 mg/L used,
and
Kpo and a = constants that express the equilibrium relationship between dissolved
and adsorbed forms of metals. A list of constants used for each hardness -dependent
metal can also be found in the RPA program under a sheet labeled DPCs.
4. The numeric standard for each metal of concern is divided by the default partition coefficient (or
site -specific translator) to obtain a Total Recoverable Metal at ambient conditions.
In some cases, where an EPA default partition coefficient translator does not exist (ie. silver), the
dissolved numeric standard for each metal of concern is divided by the EPA conversion factor to
obtain a Total Recoverable Metal at ambient conditions. This method presumes that the metal is
dissolved to the same extent as it was during EPA's criteria development for metals. For more
information on conversion factors see the June, 1996 EPA Translator Guidance Document.
5. The RPA spreadsheet uses a mass balance equation to determine the total allowable concentration
(permit limits) for each pollutant using the following equation:
Ca = (s7Q 10 + Qw) Cwgs) — (s7Q 10) (Cb)
Qw
Where: Ca = allowable effluent concentration (µg/L or mg/L)
Cwqs = NC Water Quality Standard or federal criteria (µg/L or mg/L)
Cb = background concentration: assume zero for all toxicants except NH3* (µg/L or mg/L)
Qw = permitted effluent flow (cfs, match s7Q 10)
s7Q 10 = summer low flow used to protect aquatic life from chronic toxicity and human
health through the consumption of water, fish, and shellfish from noncarcinogens (cfs)
* Discussions are on -going with EPA on how best to address background concentrations
Flows other than s7Q 10 may be incorporated as applicable:
IQ 10 = used in the equation to protect aquatic life from acute toxicity
Page 3 of 4

Permit No. NC00226751
QA = used in the equation to protect human health through the consumption of water,
fish, and shellfish from carcinogens
30Q2 = used in the equation to protect aesthetic quality
6. The permit writer enters the most recent 2-3 years of effluent data for each pollutant of concern.
Data entered must have been taken within four and one-half years prior to the date of the permit
application (40 CFR 122.21). The RPA spreadsheet estimates the 95th percentile upper
concentration of each pollutant. The Predicted Max concentrations are compared to the Total
allowable concentrations to determine if a permit limit is necessary. If the predicted max exceeds
the acute or chronic Total allowable concentrations, the discharge is considered to show
reasonable potential to violate the water quality standard, and a permit limit (Total allowable
concentration) is included in the permit in accordance with the U.S. EPA Technical Support
Document for Water Quality -Based Toxics Control published in 1991.
7. When appropriate, permit writers develop facility specific compliance schedules in accordance
with the EPA Headquarters Memo dated May 10, 2007 from James Hanlon to Alexis Strauss on
40 CFR 122.47 Compliance Schedule Requirements.
The Total Chromium NC WQS was removed and replaced with trivalent chromium and
hexavalent chromium Water Quality Standards. As a cost savings measure, total chromium data
results may be used as a conservative surrogate in cases where there are no analytical results
based on chromium III or VI. In these cases, the projected maximum concentration (95th %) for
total chromium will be compared against water quality standards for chromium III and
chromium VI.
9. Effluent hardness sampling and instream hardness sampling, upstream of the discharge, are
inserted into all permits with facilities monitoring for hardness -dependent metals to ensure the
accuracy of the permit limits and to build a more robust hardness dataset.
10. Hardness and flow values used in the Reasonable Potential Analysis for this permit included:
Parameter
Value
Comments (Data Source)
Average Effluent Hardness (mg/L)
40 mg/l
[Total as, CaCO3 or (Ca+Mg)]
Average Upstream Hardness (mg/L)
N/A
[Total as, CaCO3 or (Ca+Mg)]
7Q10 summer (cfs)
0
1Q10 (cfs)
0
Permitted Flow (MGD)
1.15
Date: l 1 /14/2023
Permit Writer: _ Teresa Rodriguez
Page 4 of 4

NH3/TRC WLA Calculations
Facility: Windsor W WTP
PermitNo. NC0026751
Prepared By: Teresa Rodriguez
Enter Design Flow (MGD): 1.15
Enter s7Q10 (cfs): 0
Enter w7Q10 (cfs): 0
Total Residual Chlorine (TRC) Ammonia (Summer)
Daily Maximum Limit (ug/1) Monthly Average Limit (mg NH3-N/1)
s7Q10 (CFS)
0
s7Q10 (CFS)
0
DESIGN FLOW (MGD)
1.15
DESIGN FLOW (MGD)
1.15
DESIGN FLOW (CFS)
1.7825
DESIGN FLOW (CFS)
1.7825
STREAM STD (UG/L)
17.0
STREAM STD (MG/L)
1.0
Upstream Bkgd (ug/1)
0
Upstream Bkgd (mg/1)
0.22
IWC (%)
100.00
IWC (%)
100.00
Allowable Conc. (ug/1)
17
Allowable Conc. (mg/1)
1
Cap at 28 ug/L. Consistent with current limit.
Consistent with current
limit. Maintain limit.
Maintain limit.
Ammonia (Winter)
Monthly Average Limit (mg NH3-N/1)
Fecal Coliform
w7Q10 (CFS)
0
Monthly Average Limit:
200/100mI
DESIGN FLOW (MGD)
1.15
(If DF >331; Monitor)
DESIGN FLOW (CFS)
1.7825
(If DF<331; Limit)
STREAM STD (MG/L)
1.8
Dilution Factor (DF)
1.00
Upstream Bkgd (mg/1)
0.22
IWC (%)
100.00
Allowable Conc. (mg/1)
2
Consistent with current
limit. Maintain limit.
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/I, Monitor Only
2. Monthly Avg limit x 3 = Weekly Avg limit (Municipals)
3. Monthly Avg limit x 5 = Daily Max limit (Non-Munis)
If the allowable ammonia concentration is > 35 mg/L, no limit shall be imposed
Fecal Coliform
1. Monthly Avg limit x 2 = 400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non -Muni)

Whole Effluent Toxicity Testing and Self Monitoring Summary
Wilkesboro Cub Creek WWTP
NCO021717/001 County:
Wilkes
Ceri7dPF
Begin: 2/1/2016
chr lim: 3.7%; if PF 6.
NonComp:
Single
J
F M
A
M
2019
-
- >14.8(P) Pass
-
-
2020
-
- Pass
-
-
2021
-
- Pass >14.8(P)
-
-
2022
-
- Pass
-
-
2023
-
- Pass
-
-
Williamston WWTP
NCO020044/001 County:
Martin
Ceri7dPF
Begin: 9/1/2023
chr lim: 2.0 MGD @ 0
NonComp:
Single
J
F M
A
M
2019
-
- Pass
-
-
2020
-
- Pass
-
-
2021
-
- Pass >1.08(P)
-
-
2022
-
- Pass
-
-
2023
-
- Pass
-
-
Wilson-Hominv Crk WRF-Contentnea
NCO023906/001 County:
Wilson
Ceri7dPF
Begin: 3/1/2021
chr lim: 90%
NonComp:
Single
J
F M
A
M
2019
-
Pass -
-
>100(P
2020
-
Pass -
-
Pa!
2021
-
Pass -
-
Pa!
2022
- >100 (P) Pass -
-
Pa!
2023
-
Pass -
>100
INVALII
Windsor WWTP
NCO026751/001
Ceri7dPF
Begin: 4/1/2019
Chr Lim: 90%
J
F M
2019
Pass
- -
2020
Pass
- -
2021
Pass
- -
2022
Pass
- -
2023
>100 Pass
- -
Winston-Salem Archie Elledge WWTP
NCO037834/001
Ceri7dPF
Begin: 8/1/2017
chr lim: 76%
J
F M
2019
Pass
- -
2020
Pass
- -
2021
Pass
- -
2022
Pass
- -
2023
Pass
- -
Region: WSRO Basin: YAD01 Mar Jun Sep Dec
7Q10: 196 PF: 4.9 IWC: 3.72 Freq: Q
J J A S O
Pass - - Pass -
Pass - - Pass -
Pass >14.8(P) - - Pass >14.8(P) -
Pass - - Pass -
Pass
Region: WARO Basin: ROA09 Mar Jun Sep Dec
7Q10: 1170 PF: 2.4 IWC: 0.26 Freq: Q
J J A 5 O
Pass - - Pass -
Pass - - >1.08(P)Pass -
>1.08(P) Pass - - Pass -
Pass - - Pass -
Pass
Region: RRO Basin: NEU07 Feb May Aug Nov
70.10: 0.5 PF: 14.0 IWC: 97.37 Freq: Q
J 1 A 5 O
Pass
Pass
Pass
Pass
Pass
County: Bertie
Region: WARO
NonComp:
SINGLE
70.10: 0.0
A
M
J
J
Fail
>100
>100
Pass
Pass
-
-
Pass
Pass
-
-
Pass
Pass
-
>100 (P)
Pass
Pass
-
-
Pass
County: Forsyth
Region: WSRO
NonComp:
ChV Avg
7Q10: 15.0
A
M
J
1
Pass
-
-
Pass
Pass
-
-
Pass
Pass
-
-
Pass
Pass
-
-
Pass
Pass
-
-
Fail
Basin: ROA10 Jan Apr Jul Oct
PF: 1.15 IWC: 100 Freq: Q
A S O
Pass
Pass
Pass
>100 Pass
Basin: YAD04 Jan Apr Jul Oct
PF: 30 IWC: 75.6 Freq: Q
A S O
Pass
- - Pass>96% (P)
- Pass
Pass
>100
SOC JOC:
N
SOC JOC:
N
SOC JOC:
N
Pass
Pass >100 (P)
Pass >100 (P)
Pass
SOC JOC:
N
SOC JOC:
N
>96(P)
D
Pass
Pass
Pass>14.8 (P)
Pass
D
Pass
0.76 (P) Pass
Pass
Pass
0
It
0
Legend: P= Fathead minnow (Pimohales oromelas). H=No Flow (facilitv is active). s = Solit test between Certified Labs Page 113 of 115

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
S. DANIEL SMITH
Dlrertor
Allen Castelloe
Town of Windsor
PO Box 508
Windsor, NC 27983-0508
!!! fir- '
NORTH CAROLINA
Envhro enfoi Quolffy
November 18, 2021
SUBJECT: Compliance Inspection Report
Windsor WWTP
NPDES WW Permit No. NCO026751
Bertie County
Dear Mr. Castelloe:
The North Carolina Division of Water Resources conducted an inspection of the Windsor WWTP on
11/09/2021. This inspection was conducted to verify that the facility is operating in compliance with the
conditions and limitations specified in NPDES WW Permit No. NC0026751. The findings and comments
noted during this inspection are provided in the enclosed copy of the inspection report entitled
"Compliance Inspection Report".
There were no significant issues or findings noted during the inspection and therefore, a response to this
inspection report is not required. The facility was found to be compliant with NPDES permit #NC0026751.
If you should have any questions, please do not hesitate to contact Paul Mays with the Water Quality
Regional Operations Section in the Washington Regional Office at 252-948-3940 or via email at
[e-mail].
ATTACHMENTS
Cc: Laserfiche
Sincerely,
rain, M.. S
Paul Mays, Environmental Specialist I
Water Quality Regional Operations Section
Washington Regional Office
Division of Water Resources, NCDEQ
hashmu,cn&rq�u: pl��,ew]w'ash'uvgi:�n sa.��e Map wa,+I�Vh.:t�a*i.Cm��Fvlrgv�

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 yrlmolday Inspection Type Inspector Fac Type
1 IN 1 2 15 1 3 1 NC0026751 111 12 21/11/09 17 18 ICI 19 I s I 20I
211 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 J6
Inspection
.1. „ .I_,..,1.__ ..I
Work Days Facility Self -Monitoring Evaluation Rating B1 QA ----------------------Reserved------------------
67
72 Lti-I 73174 79 1 1 1 1 180
70 L71 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 21/11/09
19/04/01
Windsor WWTP
NCSR 1527
Exit Time/Date
Permit Expiration Date
Windsor NC 27983
10:00AM 21/11/09
23/05/31
Name(s) of Onsite Representative(s)Rtles(s)IPhone and Fax Number(s)
Other Facility Data
❑1
Linda A. Askew/ORC/252-794-49151
Name, Address of Responsible OfficialRtle/Phone and Fax Number
Contacted
Allen Castelloe,PO Box 508 Windsor NC 2798305081Town
No
Administrator1252-794-31211
Section C: Areas Evaluated During Inspection (Check only those areas evaluated)
Permit 0 Flow Measurement Operations & Maintenar Records/Reports
Self -Monitoring Progran 0 Sludge Handling Dispo: Facility Site Review Laboratory
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
(See attachment summary)
Name(s) and Signature(s) of Inspector(s) Agency/Office/Phone and Fax Numbers Date
Paul M Mays DWRIWARO WQ1252-948-39401
Signature of Management QA Reviewer Agency/OfFicelPhone and Fax Numbers Date
EPA Form 3560-3 (Rev 9-94) Previous editions are obsolete.
Page##

NPDES yr/mo/day Inspection Type (Cont.)
31 Nco026751^ I11 1 21/41109 17 18 U
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
On 11/09/2021 from 09:00am to 10:00am Paul Mays with the Division of Water Resources from the
Washington Regional Office conducted a compliance evaluation of Windsor WWTP. The facility was
found to be compliant with NDPI=S permit #NC0026751. Below are the findings and observations
made during the inspection:
A record review from 11/2019 to 11/2021 found that the facility received 2 NODs of this timeframe.
The first NOD was issued for a copper limit violation on the facility's 11/2019 eDMR and the second
NOD was issued for a BOD limit violation on the facility's 04/2020 eDMR. Both NODS were discussed
with ORD Linda Askew during the inspection.
The Town of Windsor is lab certified and operated under certificate #557. Windsor WWTP uses the
lab to sample pH, BOD, Fecal, TSS, Ammonia, Chlorine, DO, and Temp. The fecal incubator was set
to exactly 44.5 degrees Celsius and the BOD incubator was set to exactly 20.0 degrees Celsius. The
lab appeared to be in good condition and all lab equipment appeared to be in good working
condition.
The 04/2021 DMR and 07/2021 DMR were spot checked with no discrepancies found between the
lab data and the reports. The 2021 and 2020 annual compliance reports were also available,
complete, and readily available for review. The ORC visitation log was also complete and ready for
review. The ORC stated records are kept for at least 3 years and lab records were kept for a least 5
years as required by permit #NC0026751. ORC Linda Askew was also very helpful during the record
review.
The grit auger was down during the time of the inspection. The facility had people out to repair it on
the day of the inspection. It was said that the auger was in working condition and went down recently.
WARO was informed that the auger should be back in working order again on 11 /10/2021.
At the time of inspection Clarifier 2 was down for repairs and both Clarifier 1 and Clarifier have
repairs planned for them in the future. It was found that Clarifier 2 had been sandblasted and a new
coat of cement had been applied. Clarifier 1 had already been sandblasted and will be finished at a
later date. Clarifier 1 had a sludge blanket of 2 ft, and this was measured via sludge judge.
Page#

Permit: NCO026751 Owner - Facility: Windsor WWTP
Inspection Date: 11/09/2021 Inspection Type: Compliance Evaluation
Operations $ Maintenance Yes No NA NE
Is the plant generally clean with acceptable housekeeping? ■ ❑ ❑ ❑
Does the facility analyze process control parameters, for ex: MLSS, MCRT, Settleable ■ ❑ ❑ ❑
Solids, pH, DO, Sludge Judge, and other that are applicable?
Comment:
Laboratory
Yes
No NA NE
Are field parameters performed by certified personnel or laboratory?
■
❑ ❑ ❑
Are all other parameters(excluding field parameters) performed by a certified lab?
■
❑ ❑ ❑
# Is the facility using a contract lab?
■
❑ ❑ ❑
# Is proper temperature set for sample storage (kept at less than or equal to 6.0
■
❑ ❑ ❑
degrees Celsius)?
Incubator (Fecal Coliform) set to 44.5 degrees Celsius+/- 0.2 degrees?
■
❑ ❑ ❑
Incubator (BOD) set to 20.0 degrees Celsius +/- 1.0 degrees?
■
❑ ❑ ❑
Comment: The Town of Windsor is lab certified and operated under certificate #557. Windsor
WWTP uses the lab to sample PH, BOD, Fecal, TSS, Ammonia, Chlorine,
DO, and
Temp. The fecal incubator was set to exactly 44.5 degrees Celsius and the BOD
incubator was set to exactly 20.0 degrees Celsius. The lab appeared to be in good
condition and all lab equipment appeared to be in good working condition.
Permit
Yes
No
NA NE
(If the present permit expires in 6 months or less). Has the permittee submitted a new
❑
❑
■
❑
application?
Is the facility as described in the permit?
■
❑
❑
❑
# Are there any special conditions for the permit?
■
❑
❑
❑
Is access to the plant site restricted to the general public?
■
❑
❑
❑
Is the inspector granted access to all areas for inspection?
■
❑
❑
❑
Comment:
Record Keeping
Yes
No
NA
NE
Are records kept and maintained as required by the permit?
■
❑
❑
❑
Is all required information readily available, complete and current?
■
❑
❑
❑
Are all records maintained for 3 years (lab. reg. required 5 years)?
■
❑
❑
❑
Are analytical results consistent with data reported on DMRs?
■
❑
❑
❑
Is the chain -of -custody complete?
■
❑
❑
❑
Dates, times and location of sampling
■
Name of individual performing the sampling
■
Page# 3

Permit: NCO026761 Owner - Facility: Windsor WVVTP
Inspection Date: 11/09/2021 Inspection Type: Compliance Evaluation
Record Keeping Yes No NA NE
Results of analysis and calibration
Dates of analysis
Name of person performing analyses
Transported COCs
Are DMRs complete: do they include all permit parameters?
Has the facility submitted its annual compliance report to users and DWQ?
(If the facility is = or > 5 MGD permitted flow) Do they operate 2417 with a certified
operator on each shift?
Is the ORC visitation log available and current?
Is the ORC certified at grade equal to or higher than the facility classification?
Is the backup operator certified at one grade less or greater than the facility
classification?
Is a copy of the current NPDES permit available on site?
Facility has copy of previous year's Annual Report on file for review?
• ❑ ❑ ❑
• ❑ ❑ ❑
❑ ❑ M ❑
■ ❑ ❑ ❑
■ ❑ ❑ ❑
❑ 1111
■ ❑ ❑ ❑
■ ❑ ❑ ❑
Comment: The 04/2021 DMR and 07/2021 DMR were spot checked with no discrepancies found
between the lab data and the reports. The 2021 and 2020 annual compliance reports
were also available, complete, and readily available -for review. The ORC visitation log
was also complete and ready for review. The ORC stated records are kept for at least
3 years and lab records were kept for a least 5 years as required by permit
#NC0026751. ORC Linda Askew was also very helpful during the record review.
Pump Station - Influent
Yes
No
NA
NE
Is the pump wet well free of bypass lines or structures?
❑
❑
❑
■
Is the wet well free of excessive grease?
❑
❑
❑
■
Are all pumps present?
❑
❑
❑
■
Are all pumps operable?
❑
❑
❑
■
Are float controls operable?
❑
❑
❑
Is SCADA telemetry available and operational?
0
❑
❑
❑
Is audible and visual alarm available and operational?
❑
❑
❑
■
Comment:
Bar Screens Yes No NA NE
Type of bar screen
a.Manual
b.Mechanical ❑
Page# 4

Permit: NCO026751
Inspection Date: 11/09/2021
Owner - Facility: Windsor WwTP
Inspection Type: Compliance Evaluation
Bar Screens
Yes
No
NA NE
Are the bars adequately screening debris?
■
❑
❑
❑
Is the screen free of excessive debris?
■
❑
❑
❑
Is disposal of screening in compliance?
❑
❑
❑
■
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?
❑
❑
❑
■
Is the grit free of excessive odor?
❑
❑
❑
■
# Is disposal of grit in compliance?
❑
❑
❑
■
Comment: The grit auger was down during the time of the inspection.
The facility had people out
to repair it on the day of the inspection. It was said that the auger was in working
condition and went down recently. WARO was informed that the auger should be back
in working order again on 11/10/2021.
Aeration Basins
Yes
No
NA NE
Mode of operation
Type of aeration system
Surface
Is the basin free of dead spots?
■
❑
❑
❑
Are surface aerators and mixers operational?
■
❑
❑
❑
Are the diffusers operational?
■
❑
❑
❑
Is the foam the proper color for the treatment process?
■
❑
❑
❑
Does the foam cover less than 25% of the basin's surface?
■
❑
❑
❑
Is the DO level acceptable?
❑
❑
❑
■
Is the DO level acceptable?(1.0 to 3.0 mgll)
❑
❑
❑
■
Comment:
Secondary Clarifier
Yes
No
NA NE
Is the clarifier free of black and odorous wastewater?
■
❑
❑
❑
Is the site free of excessive buildup of solids in center well of circular clarifier?
■
❑
❑
❑
Are weirs level?
■
❑
❑
❑
Page#E 5

Permit: NCO026751 Owner - Facility: Windsor WWTP
Inspection Date: 11/09/2021 Inspection Type: Compliance Evaluation
Secondary Clarifier
Yes
No
NA NE
Is the site free of weir blockage?
■
❑
❑
❑
Is the site free of evidence of short-circuiting?
■
❑
❑
❑
Is scum removal adequate?
■
❑
❑
❑
Is the site free of excessive floating sludge?
■
❑
❑
❑
Is the drive unit operational?
0
❑
❑
❑
Is the return rate acceptable (low turbulence)?
■
❑
❑
❑
Is the overflow clear of excessive solids/pin floc?
■
❑
❑
❑
Is the sludge blanket level acceptable? (Approximately'/ of the sidewall depth)
■
❑
❑
❑
Comment: At the time of inspection Clarifier 2 was down for repairs and both Clarifier 1 and
Clarifier have repairs planned for them in the future. It was found that Clarifier 2 had
been sandblasted and a new coat of cement had been applied. Clarifier 1 had already
been sandblasted and will be finished at a later date. Clarifier 1 had a sludge blanket
of 2 ft, and this was measured via sludge judge.
Disinfection -Gas
Yes
No
NA
NE
Are cylinders secured adequately?
■
❑
❑
❑
Are cylinders protected from direct sunlight?
■
❑
❑
❑
Is there adequate reserve supply of disinfectant?
■
❑
❑
❑
Is the level of chlorine residual acceptable?
0
❑
❑
❑
Is the contact chamber free of growth, or sludge buildup?
■
❑
❑
❑
Is there chlorine residual prior to de -chlorination?
■
❑
❑
❑
Does the Stationary Source have more than 2500 lbs of Chlorine (CAS No.
❑
❑
■
❑
7782-50-5)?
If yes, then is there a Risk Management Plan on site?
❑
❑
■
❑
If yes, then what is the EPA twelve digit ID Number? (1000-
If yes, then when was the RMP last updated?
Comment:
De -chlorination
Yes
No
NA
NE
Type of system ?
Liquid
Is the feed ratio proportional to chlorine amount (1 to 1)?
■
❑
❑
❑
Is storage appropriate for cylinders?
■
❑
❑
❑
# Is de -chlorination substance stored away from chlorine containers?
■
❑
❑
❑
Are the tablets the proper size and type?
❑
❑
N
❑
Comment: Calcium Thiosulfate is used for de -chlorination
Page# 6

Permit: NCO026751 Owner - Facility: Windsor WWTP
Inspection Date: 11/09/2021 Inspection Type: Compliance Evaluation
De -chlorination Yes No NA NE
Are tablet de -chlorinators operational? ❑ ❑ ■ ❑
Number of tubes in use?
Comment:
Flow Measurement - Effluent
Yes
No
NA NE
# Is flow meter used for reporting?
■
❑
❑
❑
Is flow meter calibrated annually?
■
❑
❑
❑
Is the flow meter operational?
0
❑
❑
❑
(If units are separated) Does the chart recorder match the flow meter?
❑
❑
❑
Comment: Effluent meter was calibrated on 02/10/2021 by Delta Systems.
Effluent Sampling Yes
No
NA NE
Is composite sampling flow proportional?
■
❑
❑
❑
Is sample collected below all treatment units?
■
❑
❑
❑
Is proper volume collected?
■
❑
❑
❑
Is the tubing clean?
■
❑
❑
❑
# Is proper temperature set for sample storage (kept at less than or equal to 6.0
■
❑
❑
❑
degrees Celsius)?
Is the facility sampling performed as required by the permit (frequency, sampling type
■
❑
❑
❑
representative)?
Comment: Effluent sampler is flow proportional, 200 samples are taken per day and sampler
was
set to take 100m1 per sampling event. Effluent sampler temperature was 2 degrees
Celsius at the time of inspection.
Standby Power
Yes
No
NA NE
Is automatically activated standby power available?
M
❑
❑
❑
Is the generator tested by interrupting primary power source?
■
❑
❑
❑
Is the generator tested under load?
■
❑
❑
❑
Was generator tested & operational during the inspection?
■
❑
❑
❑
Do the generator(s) have adequate capacity to operate the entire wastewater site?
■
❑
❑
❑
Is there an emergency agreement with a fuel vendor for extended run on back-up
■
❑
❑
❑
power?
Is the generator fuel level monitored?
■
❑
❑
❑
Comment; Windsor WWTP has an emergency fuel agreement with Jernigan Oil.
Page# 7