A Division of the Georgia Department of Natural Resources

Special Permit Conditions

The following sections define special site specific conditions that may be enforceable through a permit as a supplement to numeric effluent limitations:


Combined Sewer Overflows (CSOs)

A combined Sewer Overflow (CSO) is the discharge of combined sewerage from a combined sewer system into waters of the State at a point prior to receiving minimum treatment. A combined sewer system (CSS) is a wastewater collection system owned by a State or municipality (as defined by section 502(4) of the CWA) which conveys both sanitary wastewaters and stormwater through a single-pipe system to a Publicly Owned Treatment Works (POTW) as defined in 40 CFR Part 403.3(q), and therefore, communities utilizing these systems must obtain a NPDES permit to discharge.

All NPDES permits must be written to meet Water Quality Standards including numeric criteria, narratives, and mixing provisions. This applies to permits that contain CSO outfalls. CSO permits must initially implement the nine minimum control measures and applicable Long Term Control Plan (LTCP) provisions.  Upon implementation, post-construction compliance monitoring is required to allow the permitting authority to determine whether the CSO discharges achieve State Water Quality Standards (WQS).

For more information and guidance, please visit the following link: https://www.epa.gov/npdes/combined-sewer-overflows-csos


Cooling Water Intake Structures (Section 316(b))

In 2014, EPA published the final rule for Section 316(b) of the Clean Water Act (CWA) establishing requirements for the design and operation of Cooling Water Intake Structures (CWIS). In order to minimize adverse impacts to aquatic life the rule establishes Impingement Mortality Best Technology Available (BTA) standards. Applicable facilities that meet all four of the following conditions must follow regulations outlined in 40 CFR Parts 122(r) & 125 Subparts I, J, & N.

  1. The facility is a point source may discharges under a NPDES permit to waters of the State.
  2. The cooling water intake structure withdraws cooling water from waters of the State.
  3. The facility design intake flow (DIF) for all cooling water intake structures at the facility is greater than 2 MGD.
  4. The facility has an intake structure that withdraws more than 25% of the water for cooling purposes on an actual intake flow basis.

Applicable facilities that withdraw greater than 125 MGD on an actual intake flow (AIF) basis will also be subject to Entrainment BTA Standards.

Existing facilities must also complete an annual report as described in their permit. New facilities should contact the Watershed Protection Branch for more information.


Best Management Practices

Clean Water Act (CWA) sections 402(a) (1) and (2) give the permitting authority the ability to include Best Management Practices (BMPs) in permits on a case-by-case basis to carry out the provisions of the CWA. Permits may include BMPs in order to control plant site runoff, spillage or leaks, sludge or waste disposal, and drainage from raw material storage. BMP Guidance Documents for Mining and Processing Operations can be found here.


Industrial Pretreatment Program

The following POTWs accepting industrial process wastewater may be required to implement an Industrial Pretreatment Program:

  • A facility with a design flow greater than 5 MGD
  • A facility with a design flow less than 5 MGD if the nature or volume of the industrial influent warrants a program

This program may be enforceable through their NPDES or LAS permit, including but not limited to the submittal of local limit evaluations, compliance monitoring, inspections, and an annual report. The corresponding forms and annual report may be found here.

Please review the Industrial Pretreatment page and our guidance documents for the process for approval and additional information.


Long Term Biochemical Oxygen Demand (BOD)

Long Term Biochemical Oxygen Demand (BOD) testing provides a foundation for a defensible wasteload allocation (WLA). Long-Term BOD testing provides a means for separating carbonaceous BOD (CBOD) and nitrogenous BOD (NBOD), components which are required for successful water quality models. As a result, National Pollutant Discharge Elimination System (NPDES) permittees may be required to test for Long Term BOD during the permit term. 

Additional information on Long Term BOD may be found here.


Mixing Zones

A mixing zone is the area where a discharged effluent undergoes initial dilution. It is an allocated range where water quality criteria can be exceeded as long as it does not result in toxic conditions or receiving waterbody impairment. The Federal Regulations at 40 CFR 131.13 allow mixing zones at the discretion of the EPD. Georgia State Rule 391-3-6-0.03(10) allows EPD to designate a mixing zone, provided that the receiving waterbody is protected from acute toxicity to ensure a zone of safe passage for aquatic organisms. Water quality modeling may be performed in order to establish a designated mixing zone for an NPDES permit.


Reuse Standards

Urban water reuse is generally applied to the use of reclaimed water for the beneficial irrigation of areas that are intended to be accessible to the public, such as golf courses or landscaping. However, reuse water may also provide for a number of expanded uses, such as fire protection, fountains, agricultural irrigation, or industrial processes.

Due to the use of reclaimed water in areas of unrestricted public access, it is necessary that the industrial and/or domestic wastewater applied be treated to more stringent effluent limitations.  EPD thus allows permittees to provide this valuable resource to designated users through its permits. Prior to providing permitted reuse water to a designated user, written notice must be provided to EPD. The permit may then be modified to include the necessary limitations required and shall undergo a public comment period before the reuse may be approved.

For more information, please review our reuse guidelines here


Sludge Management Plans (SMP)

The disposal of sewage or domestic sludge (biosolids) generated at a wastewater treatment facility may be disposed of by any of the following means: landfill, land application, incineration, or through another third party. If a facility wishes to utilize a method other than a landfill, the facility is required to develop and receive EPD approval for a Sludge Management Plan (SMP) through a permit modification. The SMP shall be implemented in accordance with Chapter 391-3-6-.17 of the State Rules and 40 CFR 503.

Upon obtaining approval of a SMP, the permit may be modified and the plan shall be enforceable through the facility’s permit. The permittee will then be required to monitor the application of sewage sludge as specified in their permit, as well as submit an annual report in accordance with the State Rules (see reference above).

Forms and aid corresponding to the required annual report, as well as guidelines for the land application of biosolids, may be found here.

For Soil Amendment Registration Applications and Guidelines, please contact the Department of Agriculture.


Watershed Assessments (WA) & Protection Plans (WPP)

The development of a Watershed Assessment and Protection Plan is required for the following POTWs:

  • 1.0 MGD or greater
  • New Facilities
  • Expanding Facilities

The establishment of the WA and WPP is thus enforceable though the facility’s NPDES or LAS permit. Please be advised that any new or expanding facility may not be given authorization to operate until the WA and WPP have been completed and approved. For more information on the specific requirements, please visit the guidance page.


Whole Effluent Toxicity (WET) Testing

NPDES permittees may be required to conduct WET testing as part of an NPDES permit requirement, as part of the application process for reissuance of an existing NPDES permit or as otherwise required by EPD. EPD recommends that all applicants and permittees carefully review their permit and application requirements in advance in order to ensure all necessary sampling events have been conducted.

For more information on WET Testing, please visit the US EPA website.