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National Pollutant Discharge Elimination System (NPDES)

National Pretreatment Program Variances

Under the general pretreatment regulations, EPA can grant case-by-case variances from applicable categorical pretreatment standards. Entities can request adjustments in pretreatment standards and requirements in certain circumstances.

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Fundamentally Different Factors Variance

EPA can grant a variance if conditions at a specific industrial user (IU) site are fundamentally different from the factors considered when the categorical pretreatment standard was originally developed. The IU, a publicly owned treatment works (POTW), or EPA can initiate the process.

After considering an IU’s fundamentally different factors (FDF) request, EPA can grant the specific facility limits that are more or less stringent than the established standard. An applicant must submit the request for this variance no later than 180 days after the date the categorical pretreatment standards were published in the Federal Register. The state director or EPA Administrator will provide notice of the application receipt and provide an opportunity for public review and comment. EPA makes the final determination following state director review.

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Net/Gross Calculation Variance

IUs can request that their 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)] adjust their applicable categorical pretreatment standards to reflect the presence of pollutants in the IU’s intake water.

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Removal Credits Variance

A POTW can apply for the authority to grant removal credits to its IUs from an applicable categorical pretreatment standard by the amount that the POTW can consistently remove a specific pollutant. The POTW applies for, and receives, authorization from its 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)] to grant a removal credit. Removal credit applications and approvals must meet public notice requirements.

Once the credits are approved, the POTW permitting authority must include additional requirements in the POTW’s NPDES permit for implementing the removal credits. The regulations at 40 CFR Part 403.7 also identify conditions and procedures by which the approval authority may withdraw removal credits.

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