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National Pollutant Discharge Elimination System (NPDES)

Pretreatment Roles and Responsibilities-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.

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:

Additional Information

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

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