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Frequently Asked Questions
Below are questions the Stormwater Permitting Unit (SPU) hears often. This page is currently under construction with more Q&A to come.
What is my "COC"?
This refers to your "Certificate of Coverage." The COC is the documentation showing the facility is covered under one of our General Permits. The General Permit is the same for all facilities covered by that permit. The COC issued to the facility contains a unique COC number, site location, receiving waters (for NPDES permits), and sometimes details about authorized discharges. For example, a facility covered under NPDES General Permit NCG030000 may have a COC No. NCG030777.
You must send a letter to the DWQ Stormwater Permitting Unit to request recission. You should send the letter to our mailing address, and you must specify the individual permit or COC number. You may also use the Rescission Form on the NPDES Stormwater Section of our website (see the 'Application Forms' tab). Please note that we coordinate with the Regional Office to process the request, which can take about 2 months.
Facilities with stormwater discharges "associated with industrial activity" may be excluded from permit coverage if industrial materials and operations are not exposed to stormwater. For more information, see the No Exposure section of our website.
“Post-construction” refers to permanent stormwater management measures that will stay in place once the project is built—not just during construction. In North Carolina, the State Stormwater Permitting Program permits built-upon area (impervious surfaces) resulting from development projects. Permitting involves review and approval of any engineered stormwater best management practices (BMPs), such as bioretention basins. There are also several locally administered programs across North Carolina that require development projects to meet post-construction stormwater requirements (Water Supply Protection Program, for example).
Stormwater permit requirements depend on the location and size of the project. A helpful resource for this question is the interactive stormwater permitting map on our website. However, please remember that local governments may have stricter requirements, or our map data may not reflect the most up-to-date boundaries. You must verify requirements with local officials.
Do stormwater monitoring samples have to be analyzed by a certified lab or entity? What about pH, which has to be done in the field?
Stormwater Discharges: North Carolina certification procedures do not apply to stormwater-only discharges at this time. However, any monitoring of discharges under an NPDES permit (including stormwater) must be conducted in accordance to test procedures approved under federal regulations in 40 CFR §136. This includes measuring pH properly within the 15-minute hold time. All labs certified by North Carolina perform analyses in accordance with federal procedures. So, even if your facility is not a classified as a Water Pollution Control System, using a North Carolina certified lab is often the easiest way to comply with NPDES Program requirements. A list of North Carolina certified labs can be found here.
PLEASE NOTE THAT THE WASTEWATER INFORMATION ABOVE REFLECTS A CHANGE IN THE SPU'S UNDERSTANDING OF DWQ CERTIFICATION PROGRAM IMPLEMENTATION (revised October 4, 2011).
My permit requires analysis for"Non-polar Oil & Grease / TPH by Method 1664 (SGT-HEM)." Is that more than one test?
No! There has been confusion over this parameter in recent permits (mainly for vehicle maintenance monitoring), and we want to clear it up. This description refers to ONE test: Non-polar Oil &Grease using EPA Method 1664 with the silica gel treatment step, in addition to hexane extraction (not JUST HEM). This gravimetric test method is an alternative way of estimating Total Petroleum Hydrocarbons (TPH), without using the more expensive gas chromatographic analysis. This parameter does not refer to TPH analysis by gas chromatograph. Future permits and DMR forms will be updated with language to avoid confusion about the term. [Please note that currently labs in NC are being certified for Revision B to that Method under 40 CFR 136.]
Benchmarks are numerical action levels for stormwater monitoring. Benchmarks are not effluent limits. Benchmarks are determined with help from DWQ’s Classification and Standards Unit and are determined using data from multiple sources including regulations such as EPA’s National Recommended Water Quality Criteria, the National Primary Drinking Water Regulation in 40 CFR 141.11, and NC Surface Water Quality Standards (found in 15A NCAC 02B regulations). When regulations do not contain information for a particular pollutant of concern, benchmarks are calculated per 15A NCAC 2B .0200 using peer-reviewed toxicity data.
In general, benchmarks are calculated to mimic acute water quality standards. The established Federal procedures for calculation of an acute standard are followed when developing the benchmarks (acute standard/benchmark is set at 1/2 of the calculated FAV or Final Acute Value). Acute standards are used because they are calculated to protect aquatic life from negative impacts due to short-term exposure to higher levels of chemicals. NC DWQ believes this best reflects the potential impacts of stormwater exposures.
Not unless conditions in your permit require you to. Either way, you must maintain records of those results for at least five (5) years and provide them to DWQ if requested (for example, by an inspector). This obligation is in the "Records Retention" requirements found in the boiler plate sections of your permit. Future standard permit requirements may explicitly require these data be reported.
If your permit requires monitoring under a tiered-response structure tied to benchmark values, "extra" samples within the same monitoring period that exceed stormwater benchmark concentrations do not count as exceedances.
No. Vehicle pressure washing wash water is a wastewater, and discharge to surface waters through storm drains is not authorized by any NPDES stormwater permit. However, these operations do not need water quality discharge permit as long as they conduct operations according to this guidance memo. (Also found on the NPDES Wastewater Guidance website.)