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National Pollutant Discharge Elimination System (NPDES)

Pretreatment Roles and Responsibilities

These three entities have the role and responsibility to develop and implement the national pretreatment program:

  • Approval authorities
    • Director in an NPDES authorized state with an approved state pretreatment program, and the appropriate EPA regional administrator in a non-NPDES authorized state or NPDES state without an approved state pretreatment program.
  • Control authorities
    • The publicly owned treatment works (POTW), for a POTW with an approved pretreatment program, or the approval authority, for a POTW without an approved pretreatment program.
  • Industrial users (IUs)
    • A nondomestic source of indirect discharge into a POTW.

More information on each of their specific responsibilities is provided in the following sections.

Approval Authorities

In a traditional pretreatment program, EPA approves a state’s NPDES authority to regulate the pretreatment program. The state includes conditions outlining pretreatment implementation requirements in NPDES permits issued to POTWs. Currently, 36 states are approved to act as the approval authorityHelpapproval authorityThe director in an NPDES Authorized State with an approved state pretreatment program, or the appropriate EPA regional administrator in a non-NPDES Authorized State or NPDES state without an approved state pretreatment program. [40 CFR 403.3(c)] for POTWs in their states.

For states not authorized to implement the pretreatment program, EPA serves as the approval authority. EPA regional staff fulfill approval authority responsibilities for 14 states that are not approved to implement the national pretreatment program. In addition, they oversee the states that are approved to implement the program.

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Approval Authorities' Responsibilities

The approval authorities:

  • determine when and where POTW pretreatment programs need to be developed,
  • set schedules and specific requirements for POTWs to develop pretreatment programs by including appropriate conditions in POTW NPDES permits or other applicable control mechanisms,
  • review and approve requests for new or modified POTW pretreatment programs,
  • provide technical guidance to control authorities,
  • review and approve requests for site-specific variances to categorical pretreatment standards,
  • review and receive control authority annual pretreatment reports,
  • evaluate POTW pretreatment program implementation by conducting pretreatment compliance audits and inspections, and
  • initiate enforcement actions against noncompliant POTWs or industries as appropriate.

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Pretreatment Program Requirements in NPDES Permits for POTWs

The approval authority is responsible for ensuring that POTWs comply with all applicable pretreatment program requirements. The NPDES permit writing authority and the pretreatment approval authority may or may not be the same entity; both authorities need to work together to ensure good quality NPDES permits.

In an application for an NPDES permit (40 CFR Part 122.21) (PDF)(33 pp, 256 K), the POTW submits information to identify and characterize the potential pollutants it receives from:

  • significant industrial users (SIUs),
  • categorical industrial users (CIUs), and
  • discharges received from hazardous waste generators, waste cleanup, or remediation sites.

Regardless of the mechanism of transport (including hauled waste), the POTW must submit information about all of these wastes.

During the life cycle of a POTW’s NPDES permit, the approval authority must require all POTWs to submit specific information for review by both the NPDES permit writing and pretreatment staff. POTWs must notify the NPDES and pretreatment approval authorities if they consider accepting:

  • any new introduction of pollutants into the POTW from an indirect discharger, which would be subject to Clean Water Act (CWA) Section 301 (PDF)(10 pp, 176 K) or 306 (PDF)(2 pp, 128 K) if it is directly discharging the pollutants, and
  • any substantial change in the volume or character of pollutants being introduced into the POTW by a source introducing pollutants into the POTW at the time the permit was issued.

This notification must include:

  • the quality and quantity of effluent introduced into the POTW, and
  • any anticipated impact of the change on the quantity or quality of effluent to be discharged from the POTW.

This requirement is from 40 CFR Part 122.42(b) - Additional Conditions Applicable to Specified Categories of NPDES Permits (applicable to State NPDES programs, see §123.25) (PDF)(6 pp, 164 K).

The permit writer considers this information when determining water quality based effluent limits and monitoring requirements for the POTW.

The NPDES permit writer also includes the following ongoing requirements in the POTW’s NPDES permits:

  • identify any SIUs discharging into the POTW subject to pretreatment standards under CWA Section 307(b) (PDF)(4 pp, 136 K) and 40 CFR Part 403 (PDF)(49 pp, 372 K),
  • submit for approval a local program when required by the approval authority and, in accordance with 40 CFR Part 403, comply with pretreatment standards to the extent applicable under CWA Section 307(b) and implement the program upon its approval, and
  • provide a written technical evaluation of the need to revise local limits under 40 CFR Part 403.5(c) (PDF)(2 pp, 164 K), following permit issuance or reissuance, if the POTW is required to develop and implement local limits.
  • submit an annual report summarizing program activities, including a summary of IU compliance, enforcement actions, and changes to the POTW pretreatment program to the approval authority in accordance with 40 CFR Part 403.12(i) (PDF)(10 pp, 216 K)

View the most recent version of 40 CFR Part 122.44(j) - Establishing Limitations, Standards, and other Permit Conditions (applicable to State NPDES programs, see § 123.25) (PDF)(6 pp, 164 K).

For more information on POTWs that are required to develop a local pretreatment program, the NPDES permit writer and pretreatment program approval authority should review:

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Additional Information

EPA provides the following guidance for approval authorities to use in reviewing, approving, and assessing POTW pretreatment programs:

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Control Authorities

Where a POTW has an approved local pretreatment program, the POTW is the control authorityHelpcontrol authorityThe POTW, in the case of a POTW with an approved pretreatment program, or the Approval Authority, in the case of a POTW without an approved pretreatment program. [paraphrased from 40 CFR 403.3(f)]. Where a POTW has not received approval, the control authority is the approved state or, in unapproved states, the EPA.

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Control Authorities' Responsibilities

The control authorities:

  • develop legal authority for their jurisdiction, local limits, standard operating procedures, and an enforcement response plan to establish and maintain an approved pretreatment program.
  • regulate IUs by:
    • issuing control mechanisms,
    • conducting monitoring and inspections,
    • receiving and reviewing reports and notifications,
    • reviewing requests for net/gross variances,
    • evaluating compliance with program requirements, and
    • taking enforcement as appropriate.
  • submit regular reports to approval authorities to describe the implementation of their pretreatment program.

The control authority is responsible for administering and enforcing pretreatment standards and requirements. The control authority’s primary goals are:

After the approval authorityHelpapproval authorityThe director in an NPDES Authorized State with an approved state pretreatment program, or the appropriate EPA regional administrator in a non-NPDES Authorized State or NPDES state without an approved state pretreatment program. [40 CFR 403.3(c)] - the EPA or approved state – approves a POTW’s pretreatment program, the POTW becomes the control authority. If the POTW is not required to develop an approved local pretreatment program and become the control authority, the approved pretreatment state or the EPA region (where the state is not approved), assumes responsibility as the control authority over industrial users discharging to the POTW.

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Developing an Approvable Pretreatment Program

The POTW submits the pretreatment program package to the approval authority for review and approval according to the requirements at 40 CFR Part 403.9 (PDF)(2 pp, 184 K). In addition to containing all the required elements, the package must also describe how the POTW will maintain the key components of its pretreatment program.

POTW pretreatment requirements at 40 CFR Part 403.8(f)(1) through (6) (PDF)(7 pp, 232 K) outline the key components of an approved POTW pretreatment program:

Once the approval authority (EPA or approved state pretreatment program) approves the POTW program, the POTW becomes the control authority to implement the local program.

Periodically, the control authority must modify its approved pretreatment program. Procedures for the modification of POTW pretreatment programs are outlined at 40 CFR 403.18 (PDF)(2 pp, 184 K). Common reasons for modifications include regulation changes (federal, state, or local) and adoption of new local limits. For example, a POTW may not have previously accepted hauled waste, and later modifies its program to incorporate legal authority, standard procedures, and pretreatment standards that apply to hauled waste.

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Implementing an Approved Pretreatment Program

The control authority must have adequate legal authority to implement its pretreatment program, as stated in the regulations at 40 CFR Part 403.8(f)(1) (PDF)(7 pp, 232 K). A control authority regulating IUs outside of its legal jurisdiction (e.g., IUs outside of a POTW’s political boundaries) must have the necessary legal authority to ensure that the program procedures can be implemented there, too. The legal authority must enable the POTW to:

  • deny or condition discharges to the POTW,
  • require compliance with pretreatment standards and requirements,
  • control IU discharges through permits, orders, or similar means,
  • require IU compliance schedules when necessary to meet applicable pretreatment standards and/or requirements and the submission of reports to demonstrate compliance,
  • inspect and monitor IUs;
  • obtain remedies for IU noncompliance, and
  • comply with confidentiality requirements.

Using legal authority, the control authority must develop and implement the required procedures outlined at 40 CFR Part 403.8(f)(20 (PDF)( pp, 232 K) to:

  • Identify and locate all IUs subject to the pretreatment programs.
  • Identify the character and volume of pollutants discharged to the POTW. The POTW will maintain an index or inventory of IUs and update the list, submitting changes to the list annually to their Approval Authorities per 40 CFR Part 403.12(i) (PDF)(10 pp, 216 K).
  • Notify IUs of applicable pretreatment standards and requirements. Frequently, POTWs provide this notification by issuing a permit or control mechanism that identifies applicable limitations and reporting requirements.
  • Receive and analyze reports and notices from the IUs.
  • Sample and analyze IU discharges and, specifically, inspect and sample SIUs annually.
  • Evaluate IUs and require measures for controlling non-routine, episodic discharges, including spills, that might cause interference or pass through or violate the POTW regulations.
  • Investigate IU noncompliance, developing and using an Enforcement Response Plan (“ERP”).
  • Provide sufficient funding, resources, personnel to carry out the requirements.
  • Develop and enforce local limits, or demonstrate that they are not necessary.
  • Submit an annual report with a summary of program activities, including a summary of IU compliance, enforcement actions, and changes to the POTW pretreatment program to the approval authority.

Learn more about requirements for controlling hauled waste.

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Additional Information

To assist the control authority in developing and implementing its pretreatment programs, EPA provides the following guidance:

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Industrial Users

An industrial user (IU) must comply with all applicable federal, state, and local pretreatment standards and requirements. Some federal requirements apply to all IUs and other requirements apply only to specific types of IUs.

An IU demonstrates compliance by:

  • performing self-monitoring,
  • submitting reports and notifications to its control authority, and
  • maintaining records of its activities.

These requirements apply to each type of IU regardless of the entity serving as the control authority. These federal requirements apply regardless of whether the IU has a control mechanism (e.g., permit or discharge authorization) from its control authority.

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Requirements for All IUs

All IUs are responsible for notifying the receiving POTW and/or control authority (if they are different entities) about the following discharges or changes to existing discharge practices:

These notifications alert the POTW and/or control authority to discharges that can affect the collection system or treatment plant. In addition, the control authority may specifically require its IUs to:

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Additional Requirements for SIUs

Because an IU can be as simple as an automated, coin-operated car wash or as complex as an automobile manufacturing plant or a synthetic chemical producer, EPA developed four criteria that define a significant industrial user (SIU):

  • is subject to categorical pretreatment standards (CIUs) under 40 CFR Part 403.6 (PDF)(7 pp, 236 K) and 40 CFR chapter I, subchapter N, except those designated as NSCIUs; or
  • discharges an average of 25,000 gallons per day or more of process wastewater to the POTW (excluding sanitary, noncontact cooling, and boiler blowdown wastewater); or
  • contributes a process wastestream that makes up five percent or more of the average dry-weather hydraulic or organic capacity of the POTW treatment plant; or
  • is designated as such by the POTW on the basis that the IU has a reasonable potential for adversely affecting the POTW’s operation or for violating any pretreatment standard or requirement [in accordance with 40 CFR Part 403.8(f)(6)] (PDF)(7 pp, 232 K).

SIUHelpSIU(1) All users subject to categorical pretreatment standards under 40 CFR 403.6 and 40 CFR chapter I, subchapter N, except those designated as NSCIUs; and (2) Any other IU that discharges an average of 25,000 gallons per day or more of process wastewater to the POTW (excluding sanitary, noncontact cooling, and boiler blowdown wastewater); contributes a process wastestream that makes up 5 percent or more of the average dry-weather hydraulic or organic capacity of the POTW treatment plant; or is designated as such by the POTW on the basis that the IU has a reasonable potential for adversely affecting the POTW’s operation or for violating any pretreatment standard or requirement [in accordance with 40 CFR 403.8(f)(6)]. [40 CFR 403.3(v)]s must comply with additional requirements in the federal regulations that include, but are not limited to the following:

  • Conduct required self-monitoring and submit periodic compliance reports every six months according to the reporting requirements for IUs not subject to categorical pretreatment standards (40 CFR Part 403.12(h)) (PDF)(10 pp, 216 K).
  • Develop and implement a slug control plan, if required by the control authority (40 CFR Part 403.8(f)(2)(vi)) (PDF)(7 pp, 232 K).

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Additional Requirements for CIUs

EPA develops national standards that are based on particular industrial processes. These standards are technology-based (i.e. they are based on the performance of treatment and control technologies); they are not based on risk or impacts upon receiving waters. These standards are found at 40 CFR Part 405-471.

Non-domestic dischargers subject to these national standards are called categorical industrial users (CIUHelpCIUAn industrial user subject to national categorical pretreatment standards.s). CIUs must comply with additional requirements in the federal regulations that include, but are not limited to, the following:

A CIU must comply with these federal requirements regardless of whether it has a control mechanism (e.g., permit or discharge authorization) from its control authority. These reports and notifications provide the POTW and/or control authority basic information on the industrial facility and regular reports on the facility’s compliance status with categorical and other applicable standards.

Additional requirements might apply if the CIU’s control authority implements optional pretreatment program provisions. The requirements should be specified in the CIU’s control mechanism. The CIU must notify its POTW and/or control authority (if they are different entities) about the following:

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Requirements for Hauled Waste

The term “hauled waste ” refers to the wastes’ transportation method to the POTW. Hauled waste might be sewage or domestic waste, or it might include non-domestic waste, or a combination of both types of waste. If an IU has its wastes hauled to the POTW, the waste must still comply with its applicable pretreatment standards and requirements.

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Additional Information

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