NC0021873_Permit (Modification)_20241104

North Carolina Department of Environmental Quality Division of Water Resources
512 North Salisbury Street 1611 Mail Service Center Raleigh, North Carolina 27699-1611
919.707.9000

November 4, 2024

Ms. Melody Shuler, Town Manager
Town of Mayodan
210 W Main Street
Mayodan, North Carolina 27027
Subject: NPDES Permit Minor Modification
Permit NC0021873
Mayodan WWTP
Rockingham County
Grade III/IV Biological WPCS
SIC Code 4952
Dear Ms. Shuler:

Division personnel have been informed of and recognize that further clarity should be added to the
permit as it pertains to the expectations for 2/year monitoring. As such, a footnote has been added
to Sections A.(1.), A.(2.) and A.(3.) stating that 2/year monitoring shall be conducted with one
sampling event occurring between January 1 and June 30, and one sampling event occurring
between July 1 and December 31. This change was discussed with and agreed to by the Town via
email correspondence on October 31, 2024. The appropriate sheets have been modified and are
enclosed.

This minor modification does not affect any other terms, conditions, or compliance actions covered
by the permit.

If you have any questions concerning this permit, please contact Nick Coco at [phone] or
via email at [e-mail].
Sincerely,

Karen Preston
Municipal Unit Supervisor
NPDES Permitting Branch
Division of Water Resources, NCDEQ

Hardcopy: NPDES Files
Central Files
Ecopy: DWR/Winston Salem Regional Office/Water Quality/Jenny Graznak
Veolia/Jamie Whitten and Nadine Blackwell
Docusign Envelope ID: BA7F08C7-F22E-4FC1-87F4-6782A7A5DBCF
Revised November 4, 2024

______________________________
Karen Preston,
NPDES Permitting Municipal Supervisor
Division of Water Resources
Permit NC0021873
Page 3 of 15

PART I
A.(1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [2.5 MGD]
[15A NCAC 02B .0400 et seq., 15A NCAC02B .0500 et seq.] Grade III
Biological Water Pollution Control System [15A NCAC 08G .0302]
(a.) During the period beginning on the effective date of the permit and lasting until the twelve (12)
month average flow for any calendar year exceeds 2.0 MGD or permit expiration, whichever is
sooner, the permittee is authorized to discharge treated municipal and industrial wastewater from
Outfall 001. Such discharges shall be limited and monitored1 by the permittee as specified below:
PARAMETER
Parameter Code
EFFLUENT LIMITS MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type
Sample
Location2
Flow 50050 2.5 MGD Continuous Recording I or E
BOD, 5 day, 20°C 3 CO310 30.0 mg/L 45.0 mg/L 2/week 4 Composite I and E
Total Suspended Solids3 CO530 30.0 mg/L 45.0 mg/L 2/week 4 Composite I and E
NH3 as N (Apr 1 - Oct 31) CO610 16.0 mg/L 35.0 mg/L 2/week 4 Composite E
NH3 as N (Nov 1 - Mar 31) CO610 Monitor and Report Weekly Composite E
Fecal Coliform
(geometric mean) 31616 200/100 mL 400/100 mL 3/Week Grab E
Total Residual Chlorine 5 50060 28 µg/L 3/Week Grab E
pH 00400 Between 6.0 and 9.0 Standard Units 3/Week Grab E
Dissolved Oxygen 00300 Monitor and Report 3/Week Grab E
Temperature (°C) 00010 Monitor and Report 3/Week Grab E
Conductivity (µmhos/cm) 00094 Monitor and Report 3/Week Grab E
Total Phosphorus (mg/L) CO665 Monitor and Report Monthly Composite E
TKN (mg/L) 00625 Monitor and Report Monthly Composite E
NO3-N + NO2-N (mg/L) 00630 Monitor and Report Monthly Composite E
Total Nitrogen 6 (mg/L) CO600 Monitor and Report Monthly Calculated E
1,4-Dioxane (µg/L)7,8 82388 Monitor and Report 2/year Grab E
PFAS various Footnote 9 Footnote 9 Grab E
Chronic Toxicity 10 TGP3B Monitor and Report Quarterly Composite E
Pollutant Scan 11 NC01 Monitor and Report Footnote 11 Footnote 11 E
Hardness -Total as CaCO3 (mg/L) 00900 Monitor and Report Quarterly Composite E
Hardness12 -Total as CaCO3 (mg/L) 00900 Monitor and Report Quarterly Grab U
Dissolved Oxygen (mg/L) 00300 Monitor and Report Variable2 Grab U and D
Temperature °C 00010 Monitor and Report Variable2 Grab U and D
Conductivity (µmhos/cm) 00094 Monitor and Report Variable2 Grab U and D
pH 31616 Monitor and Report Variable2 Grab U and D
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR’s eDMR application
system. See Special Condition A.(8.).
2. Sample locations I-Influent, E-Effluent, U-Upstream = at NC Highway 135, D-Downstream = NCSR 2177
(Dan Valley Road). Upstream and downstream samples shall be grab samples collected 3/week during June,
July, August, and September and 1/week during the remainder of the year.
3. The monthly average effluent BOD5 and Total Suspended Solids concentrations shall not exceed 15% of the
respective influent value (85% removal).
4. Twice per week sampling must occur on any two non-consecutive days during the calendar week.
Footnotes continue on the next page.
Docusign Envelope ID: BA7F08C7-F22E-4FC1-87F4-6782A7A5DBCF
Revised November 4, 2024

______________________________
Karen Preston,
NPDES Permitting Municipal Supervisor
Division of Water Resources
Permit NC0021873
Page 4 of 15

Footnotes continued from A.(1.) Effluent Limitations and Monitoring Requirements [2.5 MGD]:
5. The facility shall monitor TRC when using chlorination for disinfection. The Division shall consider all effluent
total residual chlorine values reported below 50 µg/l to be in compliance with the permit. However, the
permittee shall continue to record and submit all values reported by a North Carolina certified laboratory
(including field certified), even if these values fall below 50 µg/l.
6. For a given wastewater sample, TN = TKN + NO3-N + NO2-N, where TN is Total Nitrogen, TKN is Total
Kjeldahl Nitrogen, and NO3-N and NO2-N are Nitrate and Nitrite Nitrogen, respectively.
7. Samples will be analyzed and reported using sufficiently sensitive test procedures (i.e., methods) approved
under 40 CFR part 136 for the analysis of pollutants or pollutant parameters.
8. 2/year monitoring shall be conducted with one sampling event occurring between January 1 and June 30, and
one sampling event occurring between July 1 and December 31.
9. See Special Condition A.(7.).
10. Chronic Toxicity (Ceriodaphnia dubia) P/F at 5% with testing in March, June, September, and December. See
Special Condition A.(4.).
11. The permittee shall perform three effluent pollution scans during the term of this permit. See Special Condition
A.(5.).
12. The permittee shall sample instream hardness upstream of the facility’s discharge. The sample shall be
representative of the hardness in the stream.

There shall be no discharge of floating solids or visible foam in other than trace amounts.

Docusign Envelope ID: BA7F08C7-F22E-4FC1-87F4-6782A7A5DBCF
Revised November 4, 2024

______________________________
Karen Preston,
NPDES Permitting Municipal Supervisor
Division of Water Resources
Permit NC0021873
Page 5 of 15

A.(2.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [3.0 MGD]
[15A NCAC 02B .0400 et seq., 15A NCAC02B .0500 et seq.] Grade IV
Biological Water Pollution Control System [15A NCAC 08G .0302]
(a.) During the period beginning after the twelve (12) month average flow exceeds 2.0 MGD and
lasting until the twelve (12) month average flow for any calendar year exceeds 2.7 MGD or permit
expiration, whichever is sooner, the permittee is authorized to discharge treated municipal and
industrial wastewater from Outfall 001. Such discharges shall be limited and monitored1 by the
permittee as specified below:
PARAMETER
Parameter Code
EFFLUENT LIMITS MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type
Sample
Location2
Flow 50050 3.0 MGD Continuous Recording I or E
BOD, 5 day, 20°C 3 CO310 30.0 mg/L 45.0 mg/L Daily4 Composite I and E
Total Suspended Solids3 CO530 30.0 mg/L 45.0 mg/L Daily 4 Composite I and E
NH3 as N (Apr 1 - Oct 31) CO610 14.0 mg/L 35.0 mg/L Daily 4 Composite E
NH3 as N (Nov 1 - Mar 31) CO610 Monitor and Report 3/week 4 Composite E
Fecal Coliform
(geometric mean) 31616 200/100 mL 400/100 mL Daily Grab E
Total Residual Chlorine 5 50060 28 µg/L Daily Grab E
pH 00400 Between 6.0 and 9.0 Standard Units Daily Grab E
Dissolved Oxygen 00300 Monitor and Report Daily Grab E
Temperature (°C) 00010 Monitor and Report Daily Grab E
Conductivity (µmhos/cm) 00094 Monitor and Report Daily Grab E
Total Phosphorus (mg/L) CO665 Monitor and Report Monthly Composite E
TKN (mg/L) 00625 Monitor and Report Monthly Composite E
NO3-N + NO2-N (mg/L) 00630 Monitor and Report Monthly Composite E
Total Nitrogen 6 (mg/L) CO600 Monitor and Report Monthly Calculated E
1,4-Dioxane (µg/L)7,8 82388 Monitor and Report 2/year Grab E
PFAS various Footnote 9 Footnote 9 Grab E
Chronic Toxicity 10 TGP3B Monitor and Report Quarterly Composite E
Pollutant Scan 11 NC01 Monitor and Report Footnote 11 Footnote 11 E
Hardness -Total as CaCO3 (mg/L) 00900 Monitor and Report Quarterly Composite E
Hardness12 -Total as CaCO3 (mg/L) 00900 Monitor and Report Quarterly Grab U
Dissolved Oxygen (mg/L) 00300 Monitor and Report Variable2 Grab U and D
Temperature °C 00010 Monitor and Report Variable2 Grab U and D
Conductivity (µmhos/cm) 00094 Monitor and Report Variable2 Grab U and D
pH 31616 Monitor and Report Variable2 Grab U and D
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR’s eDMR application
system. See Special Condition A.(9.).
2. Sample locations I-Influent, E-Effluent, U-Upstream = at NC Highway 135, D-Downstream = NCSR 2177
(Dan Valley Road). Upstream and downstream samples shall be grab samples collected 3/week during June,
July, August, and September and 1/week during the remainder of the year.
3. The monthly average effluent BOD5 and Total Suspended Solids concentrations shall not exceed 15% of the
respective influent value (85% removal).

Footnotes continue on the next page.
Docusign Envelope ID: BA7F08C7-F22E-4FC1-87F4-6782A7A5DBCF
Revised November 4, 2024

______________________________
Karen Preston,
NPDES Permitting Municipal Supervisor
Division of Water Resources
Permit NC0021873
Page 6 of 15

Footnotes continued from A.(2.) Effluent Limitations and Monitoring Requirements [3.0 MGD]:
4. Once the 3.0 MGD limits page has been placed into effect and after six (6) consecutive months of sampling, the
Permittee may request a reduction in the monitoring frequency to twice per week sampling for any of the three
parameters (BOD5, TSS and NH3-N) for which no effluent permit limit violations have occurred. Twice per
week sampling must occur on any two non-consecutive days during the calendar week.
5. The facility shall monitor TRC when using chlorination for disinfection. The Division shall consider all effluent
total residual chlorine values reported below 50 µg/l to be in compliance with the permit. However, the
permittee shall continue to record and submit all values reported by a North Carolina certified laboratory
(including field certified), even if these values fall below 50 µg/l.
6. For a given wastewater sample, TN = TKN + NO3-N + NO2-N, where TN is Total Nitrogen, TKN is Total
Kjeldahl Nitrogen, and NO3-N and NO2-N are Nitrate and Nitrite Nitrogen, respectively.
7. Samples will be analyzed and reported using sufficiently sensitive test procedures (i.e., methods) approved
under 40 CFR part 136 for the analysis of pollutants or pollutant parameters.
8. 2/year monitoring shall be conducted with one sampling event occurring between January 1 and June 30, and
one sampling event occurring between July 1 and December 31.
9. See Special Condition A.(8.).
10. Chronic Toxicity (Ceriodaphnia dubia) P/F at 6% with testing in March, June, September, and December. See
Special Condition A.(4.).
11. The permittee shall perform three effluent pollution scans during the term of this permit. See Special Condition
A.(5.).
12. The permittee shall sample instream hardness upstream of the facility’s discharge. The sample shall be
representative of the hardness in the stream.

There shall be no discharge of floating solids or visible foam in other than trace amounts.

Docusign Envelope ID: BA7F08C7-F22E-4FC1-87F4-6782A7A5DBCF
Revised November 4, 2024

______________________________
Karen Preston,
NPDES Permitting Municipal Supervisor
Division of Water Resources
Permit NC0021873
Page 7 of 15

A.(3.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [4.5 MGD]
[15A NCAC 02B .0400 et seq., 15A NCAC02B .0500 et seq.] Grade IV
Biological Water Pollution Control System [15A NCAC 08G .0302]
(a.) During the period beginning after the twelve (12) month average flow for any calendar year
exceeds 2.7 MGD and lasting until permit expiration, the permittee is authorized to discharge
treated municipal and industrial wastewater from Outfall 001. Such discharges shall be limited and
monitored1 by the permittee as specified below:
PARAMETER
Parameter Code
EFFLUENT LIMITS MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type
Sample
Location2
Flow 50050 4.5 MGD Continuous Recording I or E
BOD, 5 day, 20°C 3 CO310 30.0 mg/L 45.0 mg/L Daily 4 Composite I and E
Total Suspended Solids3 CO530 30.0 mg/L 45.0 mg/L Daily 4 Composite I and E
NH3 as N (Apr 1 - Oct 31) CO610 9.0 mg/L 27.0 mg/L Daily 4 Composite E
NH3 as N (Nov 1 - Mar 31) CO610 31.5 mg/L 35.0 mg/L Daily 4 Composite E
Fecal Coliform
(geometric mean) 31616 200/100 mL 400/100 mL Daily Grab E
Total Residual Chlorine 5 50060 28 µg/L Daily Grab E
pH 00400 Between 6.0 and 9.0 Standard Units Daily Grab E
Dissolved Oxygen 00300 Monitor and Report Daily Grab E
Temperature (°C) 00010 Monitor and Report Daily Grab E
Conductivity (µmhos/cm) 00094 Monitor and Report Daily Grab E
Total Phosphorus (mg/L) CO665 Monitor and Report Monthly Composite E
TKN (mg/L) 00625 Monitor and Report Monthly Composite E
NO3-N + NO2-N (mg/L) 00630 Monitor and Report Monthly Composite E
Total Nitrogen 6 (mg/L) CO600 Monitor and Report Monthly Calculated E
1,4-Dioxane (µg/L)7,8 82388 Monitor and Report 2/year Grab E
PFAS various Footnote 9 Footnote 9 Grab E
Chronic Toxicity 10 TGP3B Monitor and Report Quarterly Composite E
Pollutant Scan11 NC01 Monitor and Report Footnote 11 Footnote 11 E
Hardness -Total as CaCO3 (mg/L) 00900 Monitor and Report Quarterly Composite E
Hardness12 -Total as CaCO3 (mg/L) 00900 Monitor and Report Quarterly Grab U
Dissolved Oxygen (mg/L) 00300 Monitor and Report Variable2 Grab U and D
Temperature °C 00010 Monitor and Report Variable2 Grab U and D
Conductivity (µmhos/cm) 00094 Monitor and Report Variable2 Grab U and D
pH 31616 Monitor and Report Variable2 Grab U and D
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR’s eDMR application
system. See Special Condition A.(9.).
2. Sample locations I-Influent, E-Effluent, U-Upstream = at NC Highway 135, D-Downstream = NCSR 2177
(Dan Valley Road). Upstream and downstream samples shall be grab samples collected 3/week during June,
July, August, and September and 1/week during the remainder of the year.
3. The monthly average effluent BOD5 and Total Suspended Solids concentrations shall not exceed 15% of the
respective influent value (85% removal).

Footnotes continue on the next page.
Docusign Envelope ID: BA7F08C7-F22E-4FC1-87F4-6782A7A5DBCF
Revised November 4, 2024

______________________________
Karen Preston,
NPDES Permitting Municipal Supervisor
Division of Water Resources
Permit NC0021873
Page 8 of 15

Footnotes continued from A.(3.) Effluent Limitations and Monitoring Requirements [4.5 MGD]:
4. Once the 4.5 MGD limits page has been placed into effect and after six (6) consecutive months of daily
sampling, the Permittee may request a reduction in the monitoring frequency to twice per week sampling for
any of the three parameters (BOD5, TSS and NH3-N) for which no effluent permit limit violations have
occurred. Twice per week sampling must occur on any two non-consecutive days during the calendar week.
5. The facility shall monitor TRC when using chlorination for disinfection. The Division shall consider all effluent
total residual chlorine values reported below 50 µg/l to be in compliance with the permit. However, the
permittee shall continue to record and submit all values reported by a North Carolina certified laboratory
(including field certified), even if these values fall below 50 µg/l.
6. For a given wastewater sample, TN = TKN + NO3-N + NO2-N, where TN is Total Nitrogen, TKN is Total
Kjeldahl Nitrogen, and NO3-N and NO2-N are Nitrate and Nitrite Nitrogen, respectively.
7. Samples will be analyzed and reported using sufficiently sensitive test procedures (i.e., methods) approved
under 40 CFR part 136 for the analysis of pollutants or pollutant parameters.
8. 2/year monitoring shall be conducted with one sampling event occurring between January 1 and June 30, and
one sampling event occurring between July 1 and December 31.
9. See Special Condition A.(8.).
10. Chronic Toxicity (Ceriodaphnia dubia) P/F at 9% with testing in March, June, September, and December. See
Special Condition A.(4.).
11. The permittee shall perform three effluent pollution scans during the term of this permit. See Special Condition
A.(5.).
12. The permittee shall sample instream hardness upstream of the facility’s discharge. The sample shall be
representative of the hardness in the stream.

There shall be no discharge of floating solids or visible foam in other than trace amounts.

Docusign Envelope ID: BA7F08C7-F22E-4FC1-87F4-6782A7A5DBCF