NC0081621_Fact Sheet_20181206

Fact Sheet
NPDES Permit No. NCO081621
Permit Writer/Email Contact Qais Banihani, [e-mail]:
Date: December 6, 2018
Division/Branch: NC Division of Water Resources/NPDES Complex Permitting
Fact Sheet Template: Version 09Jan2017
Permitting Action:
N 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 2' 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:
Table 1. Facility information
Facility Information
Applicant/Facility Name:
Water & Sewer Authority of Cabarrus County/Muddy Creek WWTP
Applicant Address:
6400 Breezy Lane, Concord, NC 28025
Facility Address:
14655 Hopewell Church Road, Midland, NC 28107
Permitted Flow:
0.15 and 0.3 MGD
Facility Type/Waste:
MINOR Municipal; domestic and industrial
Facility Class:
Class 11
Treatment Units:
Bar Screen, Equalization basin, Aeration basins, Sludge holding tanks,
Aerobic digesters, Clarifiers, Tertiary filters and UV Disinfection
Pretreatment Program (Y/N)
Yes
County:
Cabarrus
Region
Mooresville
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Briefly describe the proposed permitting action and facility background: The Water and Sewer Authority
of Cabarrus County (WSACC), herein called WSACC or Permittee, applied for a permit renewal
for Muddy Creek Wastewater Treatment Plant (WWTP). The Permittee's 5-year NPDES permit
expires on October 31, 2018. The facility serves a population of 1463 within the Town of Midland
and established a full pretreatment program in 2017 with one non -categorical Significant Industrial Users
(SIUs).
In September 2007, WSACC requested speculative effluent limits for flow expansion from 0.3
MGD to 5.0 MGD. WSACC received a speculative effluent limits letter evaluation for flow rates
of 1.0 MGD, 2.0 MGD and 5.0 MGD in November 2007.
Currently, the facility is operating at a permitted flow of 0.15 MGD. An Authorization to Construct
(A to C No. 081621A02) was issued in December 2016 for expansion from 0.15 MGD to 0.3
MGD. The facility's upgrade to 0.3 MGD is underway.
The last USGS stream flow data was obtained in November of 2015 and has been used to calculate
the IWC and other dilution factors in this fact sheet.
2. Receiving Waterbody Information:
Table 2. Receiving waterbody information
Receiving Waterbody Information
Outfalls/Receiving Stream(s):
Outfall 001 — Rocky River
Stream Segment:
13-17
Stream Classification:
C
Drainage Area (mi2):
553 1
Summer 7Q10 (cfs)
38.71
Winter 7Q 10 (cfs):
831
30Q2 (cfs):
941
Average Flow (cfs):
525 1
IWC (% effluent):
0.60% (0.15 MGD) and 1.2% (0.3 MGD)
303(d) listed/parameter:
Yes, the segment is listed in the 2016 303(d) for Copper, Zinc
and Turbidity impairment
Subject to TMDL/parameter:
Yes- State wide Mercury TMDL implementation.
Subbasin/HUC:
03-07-12; 03040105
USGS Topo Quad:
G 17 NW
1 based on information provided by USGS in 2015
3. Effluent Data Summary
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Effluent data for Outfall 001 is summarized below for the period of November 2014 through March 2018.
Table 3. Effluent Data Summary Outfall 001
Permit
Parameter
Units
Average
Max
Min
Limit
Flow
MGD
0.10
0.24
0.04
MA 0.15
WA 15.0
BOD summer
mg/l
4.00
39.00
< 2.0
MA 10.0
WA 30.0
BOD winter
mg/l
4.73
26.0
< 2.0
MA 20.0
WA 45.0
TSS
mg/l
6.38
58.8
< 2.5
MA 30.0
WA 12.0
NH3N summer
mg/1
3.15
181.0
< 0.1
MA 4.0
WA 24.0
NH3N winter
mg/1
1.32
25.6
< 0.1
MA 8.0
DO
mg/1
9.09
13.3
6.2
DA > 5.0
(geometric)
Fecal coliform
#/100 ml
91.52
5100
< I
WA 400
MA 200
DM 28.0
TRC
µg/1
NA
NA
NA
(< 50
compliance)
Temperature
° C
19.28
30.0
7.0
6.0 < pH <
PH
SU
6.63
7.2
6.0
9.0
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/l of instream standard at full permitted flow; 2) to
verify model predictions for outfall diffuser; 3) to provide data for future TMDL; 4) based on other
instream concerns. Instream monitoring may be conducted by the Permittee, and there are also
Monitoring Coalitions established in several basins that conduct instream sampling for the Permittee (in
which case instream monitoring is waived in the permit as long as coalition membership is maintained).
If applicable, summarize any instream data and what instream monitoring will beproposedfor this permit
action: The current permit requires instream monitoring for Dissolved Oxygen (DO) and Temperature.
These parameters are among those collected by the Yadkin -Pee Dee River Basin Association (YPDRBA).
Review of the coalition -collected instream data from January 2014 through December 2017 at stations
8355000 (upstream) and 8385000 (downstream) revealed that the DO standard of 5.0 mg/L was largely
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maintained, and there were no significant differences between upstream and downstream (ANOVA, p >
0.5). The average over the period analyzed indicated that DO was 7.6 mg/L for both upstream and
downstream stations. Tables 4 and 5 summarize the instream data at the upstream and downstream,
respectively.
Table 4: Instream monitoring at Upstream Station (8355000)
DO
Temperature
m /L
°C
Average
7.6
1
19.7
Max
10.4
29.3
Min
6.1
5.6
Table 5: Instream monitoring at Downstream Station (8385000)
DO
Temperature
m /L
°C
Average
7.6
1
19.6
Max
10.5
29.1
Min
6.2
5.4
Temperature values were nearly identical between upstream and downstream sites with a maximum
differential being 1.1 °C, less than the 2.8 °C temperature standard in NCAC 2B. This draft permit maintains
the same instream monitoring requirements for DO and Temperature.
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)
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): The facility reported a total of
4 limit violations from October 2014 to May 2018. Broken down by parameter, these include 1 BOD5, 1
Fecal Coliform and 2 NH3-N. The BOD5 exceeded the weekly average in July 2017, Fecal coliform
exceeded the weekly geometric mean in January 2017 and NH3-N exceeded the weekly average and the
monthly average in July 2017. The violations resulted in 3 Notices of Violation (NOVs) and 1 Notice of
Deficiency (NOD).
Summarize the compliance record with aquatic toxicity test limits and any second species test results
(past 5 years): NA
Summarize the results from the most recent compliance inspection: The last facility inspection conducted
in 2017 reported that the facility was operating properly.
6. Water Quality -Based Effluent Limitations (WQBELs)
Dilution and Mixin.. Zones
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In accordance with 15A NCAC 2B.0206, the following streamflows are used for dilution considerations
for development of WQBELs: 1 Q 10 streamflow (acute Aquatic Life); 7Q 10 streamflow (chronic Aquatic
Life; non -carcinogen HH); 30Q2 streamflow (aesthetics); annual average flow (carcinogen, HH).
If applicable, describe any other dilution factors considered (e.g., based on CORMIX model results): NA
If applicable, describe any mixing zones established in accordance with 15A NCAC 2B.0204(b): NA
Oxygen -Consuming Waste Limitations
Limitations for oxygen -consuming waste (e.g., BOD) are generally based on water quality modeling to
ensure protection of the instream dissolved oxygen (DO) water quality standard. Secondary TBEL limits
(e.g., BOD= 30 mg/1 for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
If permit limits are more stringent than TBELs, describe how limits were developed Limitations for BOD
are based on 1993 QUAL2E model for instream DO protection. No changes are proposed from the current
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/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 ug/1) and capped at 28 ug/l (acute impacts). Due to analytical issues, all TRC values
reported below 50 ug/l are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal: Wasteload
Allocation (WLA) calculations resulted in a cap of 28 µg/L TRC, which is the same as in the current permit.
Therefore, there are no proposed changes for TRC.
No changes in ammonia nitrogen limits are proposed from the current permit for both flow tiers. Table 6
summarizes the NH3-N limit for each tiered flow.
Table 6. NH3-N Limit
Q=0.15MGD
Q=0.3MGD
Season
Monthly
Average
Weekly
Average
Monthly
Average
Weekly
Average
Summer
4.0 mg/L
12.0 mg/L
4.0 mg/L
12.0 mg/L
Winter
8.0 mg/L
24.0 mg/L
8.0 mg/L
24.0 mg/L
Reasonable Potential Analysis (RPA) for Toxicants
If applicable, conduct RPA analysis and complete information below.
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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 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 2017
and March 2018. 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: NA
• 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: NA
• No Limit or Monitoring: The following parameters will not receive a limit or monitoring, since
they did not demonstrate reasonable potential to exceed applicable water quality
standards/criteria and the maximum predicted concentration was <50% of the allowable
concentration: Arsenic, Beryllium, Cadmium, Total Chromium, Copper, Lead, Nickel,
Selenium, Silver and Zinc.
• POTW Effluent Pollutant Scan Review: Three effluent pollutant scans were evaluated for
additional pollutants of concern.
o The following parameter(s) will receive a water quality -based effluent limit (WQBEL)
with monitoring, since as part of a limited data set, two samples exceeded the allowable
discharge concentration: NA
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: NA
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.
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: Toxicity testing is not currently required since the facility is
classified as a minor without pretreatment program. However, the facility established a full pretreatment
program in 2017; therefore, a chronic WET limit at 0.60% (0.15 MGD) and 1.2% (0.3 MGD) effluent will
be added to the permit on a quarterly frequency.
Page 6 of 11

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 7. Mercury Effluent Data Summary - 0.15 MGD
2017
2018
# of Samples
2
1
Annual Average Conc. n /L
0.5
0.5
Maximum Conc., n L
0.5
0.5
TBEL, n /L
47
WQBEL, n /L
2009.4
Table 8. Mercury Effluent Data Summary - 0.3 MGD
2017
2018
# of Samples
2
1
Annual Average Conc. n /L
0.5
0.5
Maximum Conc., n L
0.5
0.5
TBEL, n /L
47
WQBEL, n /L
1010.7
Describe proposed permit actions based on mercury evaluation: Since no annual average mercury
concentration exceeded the WQBEL, and no individual mercury sample exceeded the TBEL, no mercury
limit is required for both flow tiers. However, since this is a minor municipal facility (< 1 MGD) with no
mercury limit required, the facility will be required to monitor mercury as part of its three effluent pollutant
scans using EPA test method 1631 E for both flow tiers.
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation
within this permit: NO TMDL for Turbidity for Rocky River in Yadkin -Pee Dee River Basin.
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: NA
If applicable, describe any special actions (HQW or ORW) this receiving stream and classification shall
comply with in order to protect the designated waterbody: NA
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If applicable, describe any compliance schedules proposed for this permit renewal in accordance with
1 SA NCAC 2K 0107(c)(2)(B), 40CFR 122.47, and EPA May 2007 Memo: NA
If applicable, describe any water quality standards variances proposed in accordance with NCGS 143-
215.3(e) and 15A NCAC 2B. 0226 for this permit renewal: NA
7. Technology -Based Effluent Limitations (TBELs)
Municipals if not applicable, delete and skip to Industrials)
Are concentration limits in the permit at least as stringent as secondary treatment requirements (30 mg/l
BODS/TSS for Monthly Average, and 45 mg/l for BODS/TSS for Weekly Average). YES
If NO, provide a justification for alternative limitations (e.g., waste stabilization pond). NA
Are 85% removal requirements for BOD51TSS included in the permit? YES
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 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): NO
If YES, confirm that antibacksliding provisions are not violated: NA
10. Monitoring Requirements
Monitoring frequencies for NPDES permitting are established in accordance with the following regulations
and guidance: 1) State Regulation for Surface Water Monitoring, 15A NCAC 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
Page 8 of 11

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's request to modify the monitoring frequency for BOD5, TSS, NH3-N and Fecal Coliform was
approved in September 2014. Review of effluent data from March 2015 through March 2018 for the above
parameters revealed that the facility's performance still satisfies the criteria established in the "DWQ
Guidance Regarding the Reduction of Monitoring Frequencies in NPDES Permits for Exceptionally
Performing Facilities" and justifies reduced monitoring for these parameters. Attached to the fact sheet is
the Data Summary for Reduced NPDES Permit Monitoring Frequency. Therefore, the reduced monitoring
frequencies will be maintained for BOD5, TSS, NH3-N and Fecal Coliform.
11. Electronic Reporting Requirements
The US EPA NPDES Electronic Reporting Rule was finalized on December 21, 2015. Effective December
21, 2016, NPDES regulated facilities are required to submit Discharge Monitoring Reports (DMRs)
electronically. Effective December 21, 2020, NPDES regulated facilities will be required to submit
additional NPDES reports electronically. This permit contains the requirements for electronic reporting,
consistent with Federal requirements.
12.Summary of Proposed Permitting Actions:
Table 9. Current Permit Conditions and Proposed Changes 0.15, 0.3 MGD
Parameter
Current Permit IL
Proposed Change
Basis for Condition/Change
Flow
MA 0.15 & 0.3 MGD
No change
15A NCAC 2B .0505
BOD5
Summer:
No change
WQBEL. Based on 1993 QUAL2E
MA 10.0 mg/l
model
WA 15.0 mg/l
Winter:
MA 20.0 mg/l
WA 30.0 mg/l
TSS
MA 30.0 mg/l
No change.
TBEL. Secondary treatment
WA 45.0 mg/l
standards/40 CFR 133 / 15A NCAC
2B .0406
NH3-N
Summer:
No change.
WQBEL. Based on 1993 QUAL2E
MA 4.0 mg/l
model.
WA 12.0 mg/l
Winter:
MA 8.0 mg/l
WA 24.0 mg/l
DO
> 5 mg/l
No change
WQBEL. State WQ standard, 15A
NCAC 2B
Fecal Coliform
MA 200 /100ml
No change
WQBEL. State WQ standard, 15A
WA 400 /100ml
NCAC 2B
Page 9 of 11

TRC
DM 28 µg/L
No change
WQBEL. Based on protection of
State WQ criteria (WLA). 15A
NCAC 2B
Temperature
Monitor 3/week
No change
WQBEL. State WQ standard, 15A
NCAC 2B
pH
6 — 9 SU
No change
WQBEL. State WQ standard, 15A
NCAC 2B
Toxicity Test at
No requirement
Chronic limit, 0.60%
WQBEL. No toxics in toxic
0.15 MGD
effluent
amounts. 15A NCAC 213.0200 and
15A NCAC 213.0500
Toxicity Test at
No requirement
Chronic limit, 1.2%
WQBEL. No toxics in toxic
0.3 MGD
effluent
amounts. 15A NCAC 213.0200 and
15A NCAC 213.0500
Effluent Pollutant
No requirement
Three times per permit
40 CFR 122
Scan
cycle
Total Hardness
No requirement
Add effluent and
Hardness -dependent dissolved
upstream Quarterly
metals water quality standards
Monitoring
approved 2016
Electronic
required
No change
In accordance with EPA Electronic
Reporting
Reporting Rule 2015.
MGD — Million gallons per day, MA - Monthly Average, WA — Weekly Average, DM — Daily Max
13. Public Notice Schedule:
Permit to Public Notice: 10/02/2018
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. Fact Sheet Addendum (if applicable):
Were there any changes made since the Draft Permit was public noticed (Yes/No): NO
If Yes, list changes and their basis below: NA
Comments Received:
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The Division did receive a comment from the Permittee. The Permittee requested to terminate the limit
requirements for the Whole Effluent Toxicity (WET) once the facility has passed 8 consecutive tests. The
limit requirements were added in accordance with 15 A NCAC 02B.0200 and 15A NCAC 2B.0500
Permittees should be aware that the objective of whole effluent toxicity limits placed in NPDES permits is
to prevent discharge of toxic substances in amounts likely to cause chronic or acute toxicity to wildlife in
the receiving stream and represents the only feasible method of evaluating the combined effects of
constituents of complex wastestreams. Following is a link to review DWR's WET
Strategy: htips:Hfiles.nc.gov/ncdeq/Water%20Qualiiy/ATU%2ODocuments/Whole%2OEffluent%20Toxi
ci , %20(WET)/WET%20Monitoring%20and%20Reporting/NCDWQ%20WET%20Strategy.pdf
Since, WET testing is a vital component to implementing water quality standards under the NPDES permits
program in accordance with the CWA Section 402, all the state environmental agencies with NPDES
programs implement WET testing; therefore, those requirements will not be terminated.
15. Fact Sheet Attachments (if applicable):
• RPA Spreadsheet Summary
• Dissolved Metals Implementation/Freshwater or Saltwater
• NH3-N and TRC WLA for 0.15 MGD and 0.3 MGD
• Mercury TMDL Evaluation
• Data Summary for Reduced NPDES Permit Monitoring Frequency
• Pretreatment information request form
• Wet Testing summary results
• Compliance Evaluation Report
• Monitoring Report Violations summary sheet
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