Pretreatment Standards and Requirements-Local Limits

Pretreatment standards are pollutant discharge limits which apply to industrial users ( IU A source of indirect discharge. [40 CFR 403.3(j)] s). Pretreatment requirements are substantive or procedural requirements applied to IUs.

Pretreatment Standards and Requirements Topics

Local limits address the specific needs and concerns of a publicly owned treatment works (POTW), its sludge, and its receiving waters. Most of the general prohibited discharge standards specified at 40 CFR Part 403.5 (PDF) (2 pp, 204 K) are not specific pollutant limitations. As a result, a POTW must evaluate its facility’s capabilities and establish local limits to protect it from receiving wastes that pass through A discharge that exits the POTW into waters of the United States in quantities or concentrations that, alone or in conjunction with a discharge or discharges from other sources, is a cause of a violation of any requirement of the POTW's NPDES permit (including an increase in the magnitude or duration of a violation). [40 CFR 403.3(p)] or interfere A discharge that, alone or in conjunction with a discharge or discharges from other sources, both (1) inhibits or disrupts the POTW, its treatment processes or operations, or its sludge processes, use, or disposal; and (2) therefore is a cause of a violation of any requirement of the POTW's NPDES permit (including an increase in the magnitude or duration of a violation) or of the prevention of sewage sludge use or disposal in compliance with . [applicable] statutory provisions and regulations or permits issued thereunder (or more stringent state or local regulations). [paraphrased from 40 CFR 403.3(k)] with operations (including sludge management).

These local limits are intended to protect:

Local limits are site-specific and can be numeric or narrative effluent discharge limits, including BMPs. EPA identifies in 40 CFR Part 403.5(c) (PDF) (2 pp, 204 K) which POTWs must develop local limits:

Evaluation of local limits is a required element of an approved POTW pretreatment program: POTWs must evaluate their local limits following each NPDES permit issuance or reissuance:

POTWs impose local limits at the end-of-pipe discharge from an industrial user (i.e., at the point of connection to the POTW's collection system). EPA can enforce local limits that are developed and approved in accordance with 40 CFR Part 403.5(c) (PDF) (2 pp, 204 K) as pretreatment standards.

Additional Information

EPA provides guidance to municipalities on how to develop local limits. The guidance includes how to calculate maximum allowable loadings, collect and analyze data, design and implement local limits, determine pollutants of concern, and perform annual reviews and periodic reevaluations of local limits: