NC0046728_Fact Sheet_20240708

NCO046728
Fact Sheet
NPDES Permit No. NCO046728
Permit Writer/Email Contact: Gary Perlmutter, [e-mail]
Date: July 8, 2024
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:
Town of Mooresville — Rocky River WWTP
Applicant Address:
P.O. Box 878, Mooresville, NC 28115
Facility Address:
369 Johnson Dairy Road, Mooresville, NC 28115
Permitted Flow:
7.5 MGD
Facility Type/Waste:
MAJOR Municipal; 88% domestic, 12% industrial'
Facility Class:
Grade IV
Treatment Units:
Influent screw pump; Equalization tanks; Mechanical screens; Aeration
lasins; Final clarifiers; Mixing tower; Filtration; UV disinfection; Cascade
aeration; RAS/WAS pumps; Aerobic digesters (diffused air); Filter belt
press; Covered sludge storage area
Pretreatment Program (Y/N):
Yes
County:
Iredell
Region:
Mooresville
Footnote:
1. Based on total permitted SIU flow of 0.9 MGD.
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NCO046728
Briefly describe the proposed permitting action and facility background: The Town of Mooresville has
applied for NPDES permit renewal for its Rocky River WWTP, and submitted a renewal application dated
9/27/2023, received by the Division on 3/5/2024. Review of the application found that an outdated EPA
Form 2A application was used, so the Permittee was requested to resubmit using the current form. The
original application included the following attachments:
1. Process narrative
2. Topographical map
3. Process flow diagram
4. Effluent Pollutant Scan laboratory reports
5. Toxicity test reports, both quarterly Ceriodaphnia and four Fathead Minnow (2°d species)
6. Industrial User Discharges
7. eDMRs from July — December 2022
A resubmittal was requested on 5/23/2024; received on 6/25/2024. The Town submitted a Chemical
Addendum on 3/29/2022, listing only Bis(2-ethylhexyl) phthalate as a potential parameter of concern,
noting that the result of 8 µg/L is likely a false positive as subsequent results were nondetects.
This facility serves a population of —47,500 residents in the Town of Mooresville. The Town operates a
pretreatment program with a long-term monitoring plan (LTMP) and receives industrial waste from three
(3) Significant Industrial User (SIUs), none of which are Categorical Industrial Users (CIUs).
The Town submitted a modeling plan to the Division in March 2024 in support of a potential flow expansion
and relocation of the outfall to Lake Norman. Based on the extensive time to process modeling and
speculative limits development, which also includes an inter -basin transfer for the potential outfall
relocation, only the current flow tier is considered in this permit renewal.
Inflow & Infiltration (I&I). The City reported on its NPDES permit renewal application an average daily
volume of 0.0038 MGD I&I. To minimize I&I, the Town is using cameras to look for sources of I&I in the
lines and if found make needed repairs or replacements.
Sludge Management Plan. Waste Activated Sludge is digested, thickened, and dewatered to a Class A
biosolids to be land applied under permit WQ0036723.
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NC0046728
2. Receiving Waterbody Information
Receiving Waterbody Information
Outfalls/Receiving Stream(s):
Outfall 001 — Dye Creek (Branch)
Stream Segment:
13-17-2
Stream Classification:
C
Drainage Area (mi2):
4.8
Summer 7Q 10 (cfs)
0.5
Winter 7Q10 (cfs):
0.9
30Q2 (cfs):
1.1
Average Flow (cfs):
5.0
IWC (% effluent):
96
2022 303(d) listed / parameter:
Yes / Benthos
Subject to TMDL / parameter:
Rocky River TMDL for Fecal Coliform (2002)
Statewide TMDL for Merc (2012)
Yadkin -Pee Dee / 0304
River Basin / HUC:
USGS Topo Quad:
Mooresville, NC
The overall assessment category of the receiving stream in 2022 is Exceeding Criteria (Category 5),
meaning it is impaired, based on successive Poor ratings for Benthos in 1985, 1990, 2001 and 2006. The
Benthos Station QB316, located —1.1 mile above the outfall in Dye Creek was last rated Fair in September
2001; Station QB315, located —350 ft below the outfall in Dye Creek was rated Poor in August 2006. The
receiving stream is —86 miles upstream of the nearest water supply boundary, WS-IV for the Blewett Falls
Lake.
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NC0046728
3. Effluent Data Summary
Effluent data is summarized below for the period November 2019 - May 2024.
Table 1. Effluent Data Summary
Parameter
Units
Average
Max
Min
Permit Limit'
Flow
MGD
5.169
12.255
2.508
7.5 MGD
BOD5 summer
mg/L
3.5
38
< 2
MA = 5.0
(Apr 1 - Oct 31)
WA = 7.5
BOD5 winter
mg/L
4.3
45
< 2
MA = 10.0
(Nov 1 - Mar 31)
WA = 15.0
BOD removal
%
99.01
99.85
88.78
> 85
Total Suspended Solids (TSS)
mg/L
6.9
191
< 2.5
MA = 30.0
WA = 45.0
TSS removal
%
98.60
99.99
50.82
> 85
NH3-N summer
mg/L
0.3
9.1
< 0.1
MA = 1.0
(Apr 1 - Oct 31)
WA = 3.0
NH3-N winter
mg/L
0.3
5.6
< 0.1
MA = 2.0
(Nov 1 - Mar 31)
WA = 6.0
Dissolved Oxygen (DO)
mg/L
8.94
15.30
7.44
DA > 6.0
pH
SU
7.41
8.54
6.68
6.0 - 9.0
Fecal Coliform
#/100 mL
�� �i
60,000
< 1
MA = 200
(geometric mean)
WA = 400
Total Residual Chlorine (TRC)
µg/L
9.4
26
< 15
DM = 17 2
Temperature
°C
20.0
27.0
12.4
Monitor & Report
Total Nitrogen (TN)
mg/L
20.45
34.40
4.48
Monitor & Report
Total Phosphorus (TP)
mg/L
1.96
5.20
0.18
Monitor & Report
Total Copper
µ
4.3
12.9
2.2
MA = 19.5 µg/Lg/L
DM = 28.3 µg/L
Total Hardness
mg/L
80.2
107
49
Monitor & Report
Footnote.
1. MA = Monthly Average; WA = Weekly Average; DA = Daily Average; DM = Daily Maximum.
2. Values up to 50 µg/L are considered compliant.
The maximum annual average daily flow was 5.43 MGD or 74.2% of the permitted flow in 2023.
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NCO046728
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).
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 (YPDRBA).
If applicable, summarize any instream data and what instream monitoring will be proposed for this
permit action: The current permit requires instream monitoring for DO, Temperature, and Total Hardness.
Hardness monitoring is upstream only, for use in calculation of hardness -dependent dissolved to total metal
standards for toxics assessment (see Section 6.4 below). The upstream location is in Dye Creek, - 1/2 mile
above the outfall, and the downstream location is in the Rocky River at NCSR 2420 (E Rocky River Rd)
and NCSR 1394 (Davidson Rd), —3.75 mi below the outfall in Mecklenburg County. Instream monitoring
is provisionally waived in light of the Permittee's participation in the Yadkin Pee Dee River Basin
Association (YPDRBA, monitoring coalition).
Data were available for review only from the permit's downstream location as that is also the location for
the Division's Ambient Monitoring System (AMS) Station Q7330000 as the outfall is —3.8 miles from the
Dye Creek headwater, as no stations are located upstream of the outfall and the closest YPDRBA station
downstream is in the Rocky River, and thus not representative of Dye Creek. Station data were obtained
from the Water Quality Portal website(hgps://www.waterqualiiydata.us/) spanning January 2019 —
December 2022 plus supplemental raw data collected from January 2023 — March 2024 from AMS staff.
Among the more recent raw data is a gap from February — August 2023 where no samples were collected
due to staffing issues. The data were reviewed and checked against applicable stream standards as well as
the results of the 2022 Integrated Report for the Rocky River (Stream Index 13-17).
Table 2. Instream Data Summary (downstream only).
Parameter
Units
Average
Max
Min
Standard
DO
mg/L
9.2
11.9
7.1
DA = 5.0
4.0 (instantaneous)
Temperature, °C
°C
16.0
27.7
5.7
32.0
Specific Conductance
PS/Cm
302
498
127
NA
Fecal Coliform
cfu/100 mL
445 (geomean)
6000
96
MA = 200
WA = 400
(geomean)
1,4-Dioxane
µg/L
1.1
2.2
1.0
NA
Ammonia
mg/L
0.05
0.38
0.02
NA
Chloride
mg/L
26.4
38
12
230
Fluoride
mg/L
0.47
0.64
0.4
1800
Hardness (as CaCO3)
mg/L
66
110
50
NA
TKN
mg/L
0.6
1.3
0.2
NA
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NCO046728
Parameter
Units
Average
Max
Min
Standard
NO2+NO3
mg/L
8.9
17
2.1
NA
pH
SU
7.3
8.3
6.6
6.0 — 9.0
Phosphorus
mg/L
1.0
2.2
0.15
NA
Sulfate
mg/L
18
24
10
NA
TSS
mg/L
36
125
8
NA
Turbidity
NTU
19
170
3
50
Footnote
1. Permit -required parameters are in bold.
Dissolved Oxygen (DO) — DO is in the permit as a parameter of concern for aquatic life. The overall
minimum at the downstream station was above the stream standard of 5.0 mg/L. The Rocky River is listed
as Meeting Criteria for DO in the 2022 Integrated Report.
Temperature — Temperature is in the permit as a parameter of concern for aquatic life. The overall maximum
was below the 32°C standard for lower piedmont and coastal plain waters. The Rocky River is listed as
Meeting Criteria for Temperature in the 2022 Integrated Report.
Conductivity — Conductivity monitoring is not required in the permit, neither effluent nor instream. The
City has an active pretreatment program with three SIUs. Specific Conductance was monitored instream, a
parameter related to Conductivity, but at 25°C. To better understand the effluent's influence on the instream
Conductivity, this parameter will be added to the permit both in the effluent and instream per 15A NCAC
02B .0508.
Fecal Coliform — Fecal Coliform instream monitoring is not in the permit. The 2022 Integrated Report
assessed the receiving stream as Data Inconclusive based on Fecal Coliform data collected in 2020, which
may be exceeding the instream standard of a geometric mean of 200/100 mL based on at least 5 samples
collected over a 30-day period or 400/100 mL in more than 20% samples collected during such period (15A
NCAC 02B .0211). Instream data are collected by AMS once a month, and upon review, the downstream
geometric mean is > 400/100 mL with over 76% of samples being > 200/100 mL and over 46% of samples
> 400/100 mL (Table 2), suggesting a high likelihood that the stream is impaired if sufficient sampling
were conducted. Based on the likelihood that the receiving stream is impaired, instream monitoring for
Fecal Coliform has been added to the permit.
Other parameters — of the 2022 Integrated Report found pH, Chloride and Fluoride to be meeting criteria
from 2020 samplings; instream data agree with the above assessments. Turbidity was assessed as exceeding
criteria from a 2020 collection; instream data found the average to be below the standard of 50 NTU, but
three samplings recorded over it: 85 NTU on 8/14/2019, 170 NTU on 12/11/2023, and 55 NTU on
1/31/2024. No changes are proposed for other parameters reviewed in this assessment.
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NC0046728
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): From June 2019 through April
2024 the facility had reported two weekly average BOD exceedances, in April 2021 resulting in a Notice
of Violation, and another in June 2023, resulting in an enforcement case. In May 2024 the facility reported
several BOD, Fecal Coliform and Ammonia exceedences, but no action was taken. According to that
month's eDMR comments, the facility was experiencing higher than normal solids inventory due to
mechanical issues involving the sludge dryer. Repairs were delayed due to unforeseeable events, causing
Operations to bypass the dryer for multiple weeks until repairs were made. DWR was notified of the event.
Summarize the compliance record with aquatic toxicity test limits and any second species test results (past
5 years): The facility passed 17 of 17 quarterly chronic toxicity tests as well as four of five second species
chronic toxicity tests, sampled in November 2021, February 2022 (pass), May 2022 (pass), August 2022
(fail) and September 2022 (pass).
Summarize the results from the most recent compliance inspection: The most recent facility inspection,
conducted on 2/20/2024, reported that overall, the facility appeared to be properly maintained and operated
with no compliance issues reported. The most recent pretreatment inspection, conducted on 2/24/2024,
found that the Town's pretreatment program is properly implemented.
6. Water Quality -Based Effluent Limitations (WQBELs)
6.1. Dilution and Mixin Zones
ones
In accordance with 15A NCAC 2B.0206, the following streamflows are used for dilution considerations
for development of WQBELs: 1Q10 streamflow (acute Aquatic Life); 7Q10 streamflow (chronic Aquatic
Life; non -carcinogen HH); 30Q2 streamflow (aesthetics); annual average flow (carcinogen, HH).
If applicable, describe any other dilution factors considered (e.g., based on CORMIX model results): NA.
If applicable, describe any mixing zones established in accordance with 15A NCAC 2B.0204(b): NA.
6.2. Oxygen -Consuming Waste Limitations
Limitations for oxygen -consuming waste (e.g., BOD) are generally based on water quality modeling to
ensure protection of the instream dissolved oxygen (DO) water quality standard. Secondary TBEL limits
(e.g., BOD = 30 mg/L for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
If permit limits are more stringent than TBELs, describe how limits were developed: BOD limits in the
current permit are from speculative limits determined for a proposed 19.0 MGD flow expansion in 2007,
based on recommendations in the 2003 Yadkin -Pee Dee Basin Plan, and applied to the 7.5 MGD expansion
in the 2009 permit. No changes are proposed.
6.3. Ammonia and Total Residual Chlorine Limitations
Limitations for ammonia are based on protection of aquatic life utilizing ammonia chronic criteria of 1.0
mg/L (summer) and 1.8 mg/L (winter). Acute ammonia limits are derived from chronic criteria, utilizing a
multiplication factor of 3 for Municipals and a multiplication factor of 5 for Non -Municipals.
Limitations for Total Residual Chlorine (TRC) are based on the NC water quality standard for protection
of aquatic life (17 µg/L) and capped at 28 µg/L (acute impacts). Due to analytical issues, all TRC values
reported below 50 µg/L are considered compliant with their permit limit.
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Describe any proposed changes to ammonia and/or TRC limits for this permit renewal: The current
Ammonia limits were placed in the 2009 permit modification for the 7.5 MGD flow tiers based on
speculative limits as an oxygen -consuming waste for a proposed expansion to 19.0 MGD prepared in 2006.
Ammonia was reviewed in the attached Wasteload Allocation (WLA) sheet for protection against ammonia
toxicity, finding the current limits to be protective. No changes are proposed.
The current TRC limit was also placed in the 2009 permit with the introduction of the 7.5 MGD flow tier,
based on 19.0 MGD speculative limits in 2006. Review of TRC in the attached WLA found the current
limit protective. No changes are proposed.
6.4. Reasonable Potential Analysis (RPA) for Toxicants
If applicable, conduct RPA analysis and complete information below. The need for toxicant limits is based
upon a demonstration of reasonable potential to exceed water quality standards (RP), 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.
The current permit requires effluent and upstream hardness monitoring for use in the RPA. Hardness data
were obtained via DMR for review; averages were 80 mg/L effluent and 37 mg/L upstream. These data
were used in the RPA.
An RPA was conducted on effluent toxicant data collected between November 2019 and May 2024 for the
following parameters: arsenic, cadmium, total chromium, copper, cyanide, lead, molybdenum, nickel,
selenium, silver, and zinc. Pollutants of concern included toxicants with positive detections and associated
water quality standards/criteria. Based on this analysis, the following permitting actions are proposed for
this permit:
• Effluent Limit with Monitoring. The following parameters will receive a water quality -based
effluent limit (WQBEL) since they demonstrated a reasonable potential to exceed applicable water
quality standards/criteria: None.
• Monitoring Only. The following parameters will receive a monitor -only requirement since they
did not demonstrate reasonable potential to exceed applicable water quality standards/criteria, but
the maximum predicted concentration was > 50% of the allowable concentration: Copper.
• 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,
Cadmium, Cyanide, Lead, Molybdenum, Nickel, Selenium, Silver, Zinc.
o Selenium had one detection at 10 µg/L, which was found in error; instead, it was a non -
detect at < 10 µg/L. Therefore, no monitoring is required.
• POTW Effluent Pollutant Scan Review: Three effluent pollutant scans (July 2021, October 2022
and January 2023) were evaluated for additional pollutants of concern. The following parameters
were detected in the scans and evaluated: Total Phenols.
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.
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NC0046728
o The following parameter(s) will receive a monitor -only requirement, since the maximum
predicted value of a limited dataset was greater than the allowable discharge concentration:
Total Phenols.
If applicable, attach a spreadsheet of the RPA results as well as a copy of the Dissolved Metals
Implementation Fact Sheet for freshwater/saltwater to this Fact Sheet. Include a printout of the RPA
Dissolved to Total Metal Calculator sheet if this is a Municipality with a Pretreatment Program.
6.5. Toxici , 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 with a chronic WET limit of 90% at
7.5 MGD flow, monitored quarterly. No changes are proposed.
6.6. Mercury Statewide TMDL Evaluation
There is a statewide TMDL for mercury approved by EPA in 2012. The TMDL target was to comply with
EPA's mercury fish tissue criteria (0.3 mg/kg) for human health protection. The TMDL established a
wasteload allocation for point sources of 37 kg/year (81 lb/year), and is applicable to municipals and
industrial facilities with known mercury discharges. Given the small contribution of mercury from point
sources (-2% of total load), the TMDL emphasizes mercury minimization plans (MMPs) for point source
control. Municipal facilities > 2 MGD and discharging quantifiable levels of mercury (> 1 ng/L) will receive
an MMP requirement. Industrials are evaluated on a case -by -case basis, depending if mercury is a pollutant
of concern. Effluent limits may also be added if annual average effluent concentrations exceed the WQBEL
value (based on the NC WQS of 12 ng/L) and/or if any individual value exceeds a TBEL value of 47 ng/L.
The current permit does not have an MMP requirement, as it was removed in the 2019 renewal based on
data review not finding any results > 2.5 ng/L. Nevertheless, the Town has reported results of 100%
compliance with the Dental Amalgam Rule in their 2023 Pretreatment Annual Report. Mercury data are
collected quarterly through the Town's LTMP. These data were reviewed for TMDL evaluation (Table 3).
Table 3. Mercury Effluent Data Summary
2020
2021
2022
2023
2024
Number of Samples
1
4
4
2
Annual Average Conc. ng/L
1.0
0.7
0.9
0.7
0.5
Maximum Conc., ng/L
1.00
1.00
1.69
0.93
0.50
TBEL, ng/L
47
WQBEL, ng/L
12.5
Describe proposed permit actions based on mercury evaluation: Since no annual average mercury
concentration exceeded the WQBEL at either flow tier, and no individual mercury sample exceeded the
TBEL (Table 5), no mercury limit is required. Several samples had quantifiable levels of mercury, but only
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NC0046728
one was > 1.0 ng/L but < 2.0 ng/L. Therefore, an MMP is not deemed necessary and is not added to the
permit.
6.7. Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation within
this permit: The facility discharges into a receiving stream that is not under a TMDL or nutrient
management strategy. The current permit requires monthly monitoring for Total Nitrogen and Total
Phosphorus, in accordance with 15A NCAC 02B .0508. To better understand the total nitrogen in the
effluent, weekly monitoring for Total Kjeldahl Nitrogen (TKN) and Nitrate -Nitrite (NO3+NO2) has been
added to the permit. No other changes are proposed.
6.8. Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: The facility discharges
into a receiving stream —86 miles above the nearest water supply boundary, WS-IV for the Blewett Falls
Lake. None of the Town's three SIUs are a potential source of 1,4-Dioxane, so this parameter is not
expected in the effluent. Therefore, no 1,4-Dioxane requirements have been added to the permit.
Due to the pervasiveness of PFAS chemicals in the environment, the presence of a downstream water supply
and the facility's receiving industrial waste from one textile SIU, an industry type recognized by the EPA
as a potential PFAS source, quarterly PFAS monitoring will be required in the permit with delayed
implementation. See Section 10 — Monitoring Requirements below for details.
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. 01 07(c) (2) (B), 40CFR 122.47, and EPA May 2007 Memo: NA.
If applicable, describe any water quality standards variances proposed in accordance with NCGS 143-
215.3(e) and 15A NCAC 2B.0226 for this permit renewal: NA.
7. Technology -Based Effluent Limitations (TBELs)
Municipals (if not applicable, delete and skip to Industrials)
Are concentration limits in the permit at least as stringent as secondary treatment requirements (30 mg/L
BOD51TSS for Monthly Average, and 45 mg/L for BODs/TSS for Weekly Average). YES.
If NO, provide a justification for alternative limitations (e.g., waste stabilization pond). NA.
Are 85% removal requirements for BOD51TSS included in the permit? YES. Review of submitted removal
rates of both parameters found no (0) occurrences of < 85% BOD removal and four (4) occurrences of <
85% TSS removal.
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
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review in accordance with 15A NCAC 2B.0201. Each applicant for a new/expanding NPDES permit must
document an effort to consider non -discharge alternatives per 15A NCAC 2H.0105(c)(2). In all cases,
existing instream water uses and the level of water quality necessary to protect the existing use is maintained
and protected.
If applicable, describe the results of the antidegradation review, including the Engineering Alternatives
Analysis (EAA) and any water quality modeling results: NA.
9. Antibacksliding Review:
Sections 402(o)(2) and 303(d)(4) of the CWA and federal regulations at 40 CFR 122.44(1) prohibit
backsliding of effluent limitations in NPDES permits. These provisions require effluent limitations in a
reissued permit to be as stringent as those in the previous permit, with some exceptions where limitations
may be relaxed (e.g., based on new information, increases in production may warrant less stringent TBEL
limits, or WQBELs may be less stringent based on updated RPA or dilution).
Are any effluent limitations less stringent than previous permit (YES/NO): YES. Total Copper limits have
been removed and monitoring frequency has been reduced from monthly to quarterly.
If YES, confirm that antibacksliding provisions are not violated: The change in Total Copper requirements
is based on RPA results using updated effluent and hardness data. The RPA demonstrated no reasonable
potential for an exceedance of Total Copper surface water standard. Monitoring is maintained to continue
tracking Total Copper in the facility effluent.
10. Monitoring Requirements
Monitoring frequencies for NPDES permitting are established in accordance with the following regulations
and guidance: 1) State Regulation for Surface Water Monitoring, 15A NCAC 2B.0500; 2) NPDES
Guidance, Monitoring Frequency for Toxic Substances (7/15/2010 Memo); 3) NPDES Guidance, Reduced
Monitoring Frequencies for Facilities with Superior Compliance (10/22/2012 Memo); 4) Best Professional
Judgement (BPJ). Per US EPA (Interim Guidance, 1996), monitoring requirements are not considered
effluent limitations under Section 402(o) of the Clean Water Act, and therefore anti -backsliding
prohibitions would not be triggered by reductions in monitoring frequencies.
All monitoring frequencies in the current permit follow 15A NCAC 02B .0508. Additional monitoring
requirements for the permit renewal include monthly NO2+NO3 and TKN. PFAS monitoring at a quarterly
frequency will be added to the permit to generate data for future evaluation. Implementation of PFAS
monitoring will be delayed until six months after the final EPA Method 1633 is published in the Federal
Register to allow laboratories to become certified in the new method.
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
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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 at 7.5 MGD'.
Parameter
Current Permit
Proposed Change
Basis for Condition/Change
MA = 7.5 MGD
Flow
Monitor influent or
No change
15A NCAC 2B .0505
effluent continuously
Summer:
MA = 5.0 mg/L
WA = 7.5 mg/L
WQBEL. Speculative limits for a
BOD5
Winter:
MA = 10.0 mg/L
No change
proposed 19.0 MGD proposed expansion
WA = 15.0 mg/L
in 2007.
Monitor influent &
effluent daily
MA = 30.0 mg/L
TSS
WA = 45.0 mg/L
No change
TBEL. Secondary treatment standards;
Monitor influent &
40 CFR 133; 15A NCAC 2B .0406.
effluent daily
di
Summer:
MA = 1.0 mg/L
%wL. Calculation results based on
WA = 3.0 mg/L
NC's use of EPA criteria in developing
Ammonia (NH3-N)
Winter:
No change
1.0 mg/L summer and 1.8 mg/L winter in
MA = 2.0 mg/L
wasteload allocations to protect against
WA = 6.0 mg/L
NH3-N toxicity. See WLA sheet
Monitor effluent daily
attached.
MA = 200 /100 mL
No change in effluent
WQBEL. WQ standard, 15A NCAC 2B
Fecal Colifc
WA = 400 /100 mL
Add instream
.0200.
Receiving stream may be impaired (rated
Monitor effluent daily
monitoring
as Data Inconclusive).
Total Residual
DM = 17.0 µg/L
No change
WQBEL. WQ standard, 15A NCAC 2B
Chlorine
Monitor effluent daily
.0200.
pH
Between 6 and 9 SU
No change
WQBEL. WQ standard, 15A NCAC 2B
Monitor effluent daily
.0200; .0500.
DA > 6.0 mg/L
DO
Monitor effluent daily
No change
WQBEL. State WQ standard, 15A
Monitor & report
NCAC 2B .0200; .0508.
instream
Monitor & report effluent
Temperature
daily
Monitor & report
No change
15A NCAC 2B.0508.
instream
Conductivity
No requirement
Add effluent and
15A NCAC 2B.0508; presence of SIUs.
instream monitoring
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NC0046728
Parameter
Current Permit
Proposed Change
Basis for Condition/Change
Total Nitrogen
Monitor &report effluent
No change
15A NCAC 2B.0508.
monthly
Total Kjeldahl
No requirement
Add monthly
To better understand nitrogen
Nitrogen (TKN)
monitoring
concentrations.
Nitrite -Nitrate
No requirement
Add monthly
To better understand nitrogen
(NO3+NO2)
monitoring
concentrations.
Total Phosphorus
Monitor & report effluent
No change
15A NCAC 2B.0508.
monthly
Quarterly effluent and
Remove instream
Based on adoption of hardness -
Total Hardness
upstream monitoring.
monitoring waiver.
dependent metals. Monitoring coalitions
will not sample for Hardness.
MA = 19.5 µg/L
Remove limits reduce
RPA: No RP found; max pred. value >
Total Copper
DM = 28.3 µg/L
monitoring to quarterly
50% allowable cone. using updated
Monitor monthly
Hardness data.
Add quarterly
RPA: RP found with limited dataset (n <
Total Phenols
No requirement
8 samples), no data above allowable
monitoring
cone.
PFAS
No requirement
Add quarterly
monitoring with delayed
EPA recommendations (guidance memo,
implementation
12/5/2022).
Ceriodaphnia dubia
Update language in
WQBEL. No toxics in toxic amounts.
Chronic Toxicity
Pass/Fail at 90 /o effluent.
special condition.
15A NCAC 2B.0200 and 15A NCAC
Monitor quarterly
213.0500.
Effluent Pollutant
Conduct three times per
Update sample years to
40 CFR 122
Scan
permit cycle
2026, 2027, 2028.
Electronic Reporting
Special Condition
Update language in
In accordance with EPA Electronic
special condition.
Reporting Rule 2015.
Footnote.
1. MGD = Million Gallons per Day; MA = Monthly Average; WA = Weekly Average; DA = Daily
Average; DM = Daily Maximum.
13. Public Notice Schedule
Permit to Public Notice: 07/23/2024
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
Gary Perlmutter at [phone] or via email at [e-mail].
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NC0046728
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):
• Three Effluent Pollutant Scans
• Four 2nd species toxicity test reports
• Sludge management description
• Chemical Addendum
• NPDES Pretreatment POC form
• Monitoring Report Violations
• WET Test summary
• Compliance Inspection report
• Pretreatment compliance inspection report
• Waste load allocations for TRC and NH3-N
• RPA sheets
• RPA Spreadsheet Summary and dissolved to total metal calculator
• Dissolved Metals Fact Sheet memo
• Mercury TMDL evaluations
Page 14 of 14