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North Carolina NPDES Industrial Stormwater General Permit Updates – What You Need to Know General Background of North Carolina Stormwater Permits

Posted: May 11th, 2023

Authors: A.J. G. 

Federal regulation 40 CFR §122.26 requires facilities with industrial stormwater discharges to apply for a National Pollutant Discharge Elimination System (NPDES) permit; either an individual permit or a general permit from an authorized state, such as North Carolina, that has promulgated NPDES authority. In North Carolina, facilities that wish to seek general permit coverage do so through the North Carolina Department of Environmental Quality (NCDEQ) NPDES General Permit No. NCGXXXXXX for Stormwater Discharges Associated with Industrial Activities.

General Permit Updates

The Division of Energy, Mineral, and Land Resources (DEMLR) is currently seeking public comment on the proposed revisions and re-issuance of NPDES Industrial Stormwater General Permits for the following industry groups:

  • NCG050000 – Apparel, Printing, Leather, Rubber
  • NCG070000 – Stone, Clay, Glass
  • NCG110000 – Treatment Works
  • NCG130000 – Nonmetal Waste and Scrap
  • NCG210000 – Timber Products

The public comment period began on April 17, 2023, and ends at 5:00 pm on May 17, 2023.  The proposed issuance date for permits in each industry group is no later than June 1, 2023, and the effective date will be June 1, 2023.

Solvent Management Plan

Each General Permit includes a Solvent Management Plan (SMP) requirement. The SMP shall be incorporated into the facilities stormwater pollution prevention plan (SWPPP). The SMP needs to include the following:

  • An annually updated and quantified inventory of solvents present on site during the previous three years
  • A narrative description of the facility locations and uses of solvents
  • The method of disposal, including quantities disposed on-site and off-site
  • The management procedures and engineering measures for assuring that solvents do not spill or leak into stormwater

PFAS Monitoring

Each General Permit also includes the following language for PFAS monitoring:

“If notified by the Director, the permittee shall monitor for Emerging Contaminants such as Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) in accordance with written notification.”

Analytical Monitoring

As a part of the General Permit updates, all facilities associated with any of the five industry groups must start conducting quarterly sampling for the following parameters in the table below.

Permittees part of the industry group NCG050000 will be allowed a 4-month grace period to prepare for analytical monitoring requirements; analytical monitoring shall begin in Quarter 3 (July 1st – September 30th) of 2023.

Permittees part of the industry groups NCG070000 and NCG130000 will be allowed a 4-month grace period to prepare for analytical monitoring requirements; analytical monitoring shall begin in Quarter 4 (October 1st – December 31st) of 2023.


Summary of Quarterly Baseline Sampling Requirements
NCG050000 NCG070000 NCG110000 NCG130000 NCG210000
Total Suspended Solids (TSS)1 100 mg/L 100 mg/L 100 mg/L 100 mg/L 100 mg/L
Chemical Oxygen Demand (COD) 120 mg/L N/A N/A 120 mg/L 120 mg/L
pH2 6-9 s.u. 6-9 s.u. 6-9 s.u. 6-9 s.u. — s.u.3
Non-Polar Oil and Grease4 15 mg/L 15 mg/L 15 mg/L 15 mg/L 15 mg/L
Fecal Coliform N/A N/A 1,000 count per 100ml N/A N/A


General Monitoring Requirements

A minimum of thirty (30) days must separate sampling events. The total rainfall amount for each sampling event shall be recorded in inches. Total rainfall shall be determined from an on-site rain gauge or a regional rain gauge located within one (1) mile of the facility. The average monthly usage of new motor and hydraulic oil used for vehicle maintenance at the facility shall be tracked and recorded.

Electronic Discharge Monitoring Reporting (eDMR)

Facilities are required to register for Electronic Discharge Monitoring Reporting (eDMR) within 30 days of the Certificate of Coverage issuance date. The NC Stormwater Electronic Discharge Monitoring Reports (eDMR) page can be found here. Submit the discharge monitoring report (DMR) within 30 days after the end of the monitoring period. When results are below detection limit, report in the format, “<XX mg/L,” where XX is the numerical value of the detection limit.

Qualitative Monitoring

Qualitative monitoring must also be conducted concurrently with analytical monitoring. The qualitative monitoring visual inspections shall be recorded on the DEMLR’s Stormwater Discharge Outfall Qualitative Monitoring Report (QMR) form. The completed qualitive monitoring visual inspection forms need to be filed onsite, and only submitted to the Division upon request.

If you have questions about how the draft General Permit updates could affect your NPDES stormwater compliance, or what your next steps should be when the General Permit updates become effective, please reach out to me at agolding@all4inc.com or Matt Dabrowski at mdabrowski@all4inc.com. ALL4 is monitoring all updates published by NCDEQ on this topic, and we are here to answer your questions and assist your facility with any aspects of industrial general stormwater compliance.

  1. TSS benchmark for High Quality Waters (HQW), Outstanding Resource Waters (ORW), Trout Waters (Tr), and Primary Nursery Areas (PNA) is 50 mg/L. NC surface water classifications can be determined using the NC DWR Surface Water Classifications Website map.
  2. The saltwater benchmark pH range is 6.8-8.5 s.u.
  3. Grab samples shall be analyzed for pH within 15 minutes of collection.
  4. Non-Polar Oil and Grease is only monitored for vehicle or equipment maintenance areas in which more than 55 Gallons of motor oil and/or hydraulic oil is used per month.


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