NPDES Permitting

Drafting Permits

Overview

Drafting NPDES permits is not a simple task. Before a permit can be drafted, the permit writer must have a complete knowledge of the regulations that apply to the specific permit application. SC Regulation R.61-9, Water Pollution Control Permits, and SC Regulation R.61-68, Water Classifications and Standards, both pertain to all NPDES permits. EPA regulations on effluent limitation guidelines apply to specific categories of industries. Also, there are development documents for each effluent limitation guideline on the categorical industries. These background documents summarize the history of the effluent guideline limitation regulation development and give the basis for the effluent guidelines. The permit writer, on occasion, must be familiar with this background information.

No one permit writer can stay familiar with every document that must be considered for a particular permit application. Therefore, for even the most experienced permit writer, time is needed to research the appropriate regulations and background information, as they relate to the application. This enables the permit writer to draft a proper permit.

Further, the permit writer must be very familiar with an applicant's operation. This includes, but is not limited to, the wastewater treatment facilities, the manufacturing facilities and practices, and the chemicals used or produced. Extensive knowledge on the receiving stream is needed by the Bureau in order to assess the potential impact of the discharge on the water quality of the receiving stream. Proposed effluent limits are developed based on this information.

The applicant is usually given an opportunity to provide input to their final draft permit prior to the public notice period. Normally, this involves about thirty to ninety days depending upon the specific permit. Applicant comments are reviewed and properly addressed before the permit is issued. This helps to avoid unnecessary appeals.

A listing of the items and/or issues that a permit writer must consider in the permit drafting process is given below. While this list is comprehensive, there may be other issues that must be considered that are not given here. Also, this listing does not give the details on how each item must be addressed or considered when drafting an NPDES permit. Rather, it gives a "laundry list" of the major items that must be considered when drafting a NPDES permit. For some items listed, a link is provided to another page on the item, or to a definition.

Permit Drafting Considerations

Administrative and technical review of application and consideration of whether or not the proposed discharge can be granted coverage under an existing general permit.
Site visit to the facility, when necessary
Determine if limits on any "Internal Waste Streams" are necessary
Establish effluent limitations for each outfall
- Review existing data
  - Effluent data
    - Discharge monitoring reports (permittee's sampling data)
    - Compliance monitoring reports (Bureau's sampling data)
  - Facility inspection reports
  - Water quality sampling data
- Review Bureau prepared Water Quality Reports, Publications, and Other Information, as appropriate, as follows:
  - Watershed Implementation Strategy
  - Special studies or reports
  - 303(d) List and other similar lists
  - Enforcement actions (previous and active)
  - Previous permit (for renewals)
  - Previous permit appeals (for renewals)
  - Similar NPDES permits
- Determine if any variances are applicable, such as:
  - Thermals under Section 316(a) of the Clean Water Act
  - Fundamentally Different Factors
- Determine "Mixing Zones" (acute and chronic)
- Determine if "Site Specific Stream Standards" apply
- Conventional pollutants (Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), Fecal Coliform, Oil and Grease, and pH)
  - For BOD, use computer stream modeling to determine waste load allocation (WLA) or, when applicable, use the Total Maximum Daily Load (TMDL). Also, see Categorical Industries and Non Categorical Industries.
  - For TSS, fecal coliform, Oil and Grease, and pH, use water quality standards considering technology based limits.
- Categorical Industries
  - Use Effluent Limitation Guidelines. For oxygen demanding substances, use guidelines in conjunction with the WLA or TMDL. Use the most stringent limit except when the most stringent limit is based on water quality standards and there is no reasonable potential to cause a water quality violation in which case use the effluent guideline limitation.
  - For pollutants of concern that are not contained in the Effluent Limitation Guideline, use Best Professional Judgment (BPJ), to establish technology based limits. Use BPJ limits in conjunction with the WLA or TMDL. Use the most stringent limit except when the most stringent limit is based on the water quality standards and there is no reasonable potential to cause a water quality violation in which case use the effluent guideline limitation.
- Non Categorical Industries (industries for which there are no effluent guidelines limitations)
  - Use Best Professional Judgment (BPJ), to establish technology based limits. Use BPJ limits in conjunction with the WLA or TMDL. Use the most stringent limit except when the most stringent limit is based on water quality standards and there is no reasonable potential to cause a water quality violation in which case use the effluent guideline limitation.
- Establish Proposed Limits for Non Conventional Pollutants (phosphorus, nitrogen, Chemical Oxygen Demand (COD), and Total Organic Carbon). For categorical industries, use applicable effluent limitations guidelines.
- Establish Proposed Limits for Toxic Pollutants
  - For each parameter of concern, a proposed effluent limit is established based on the most stringent of the derived limitations calculated on:
    - Human Health or Aquatic Life chronic and acute toxicity;
    - Organoleptic data;
    - Maximum Contaminate Levels (MCLs - drinking water standards);
    - Other published scientifically defensible data for the pollutant of concern;
    - Effluent limitation guidelines, for categorical industries; and
    - Best Professional Judgment, for non categorical industries.
- Determine if a Whole Effluent Toxicity (WET) limitation is needed. If so, determine permit requirement. Consider monitor and report, if a limitation is not needed.
- Determine if an effluent limit on color is needed.
- When requested by applicant, consider "Site Specific Effluent Limitations"
- Determine if credit must be given for "Pollutants in Intake Water"
- Evaluate Reasonable Potential for each pollutant of concern. Does the pollutant need to be limited in the permit to ensure water quality protection?
- Consider Antibacksliding issues.
- Consider "Antidegradation" issues.
- Establish final effluent limitations using the above information.
  Establish "Monitoring" requirements including recordkeeping and reporting
- For permit renewals:
  - determine if interim limits are justified.
  - If so, develop interim limits and a schedule of compliance.
- Develop NPDES Permit Rationale. An explanation for why each parameter is or is not limited in the permit and, if limited, the basis for the limitation.
Develop other Permit Conditions, as appropriate, such as:
- "Sludge Disposal and Use" requirements
- Operator requirements
- Best Management Plan requirements
- Pretreatment Program requirements for POTWs
- Ground water monitoring
- Water quality studies
- Thermal issues
- Reopener clauses
- Instream biological monitoring including benthic studies
- Special studies
Develop Fact sheet for major permits.
Establish issuance date, effective date, and expiration date (consider Watershed Program)
When developing draft permits, coordinate with other programs and entities, as appropriate:
- Bureau of Water Programs
  - Watershed Management Program
  - Drinking Water Program (Source Water Protection Areas)
  - Recreational Waters Program
  - Shellfish Program
  - Water Quality Management Plans (208 Plans) - either the Bureau of Water's 208 Planning Section for the non-designated portion of the State or the appropriate Council of Government for the designated areas
  - NPDES Stormwater Program
  - Water Pollution Enforcement Program
- DHEC's Bureau of Land and Waste Management Mining Program for mine discharges
- DHEC's Office of Ocean and Coastal Resource Management for discharges in the coastal zone.
- EPA, when applicable
After a draft permit is prepared, the permit is sent to the applicant and EPA (when applicable) for comments. Based on these comments, the draft permit limitations/requirements may be modified, as appropriate. The draft permit is then placed on public notice for public comments. Based on comments from the public, the draft permit limitations/requirements may be changed, as appropriate. The proposed permit is then issued, or denied.

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