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

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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 throughpass throughA 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 interfereinterferenceA 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:

• the POTW (including collection system infrastructure),
• receiving waters,
• workers’ health and safety, and
• sludge disposal practices.

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:

• POTWs required to develop a POTW pretreatment program per 40 CFR Part 403.8 (PDF)(7 pp, 232 K).
• POTWs without a pretreatment program where pollutants from nondomestic dischargers might result in interference or pass through and such violation is likely to recur.

• Pretreatment Program Requirements: Development and Implementation by POTW (40 CFR Part 403.8(f)(4)) (PDF)(7 pp, 232 K)

• Establishing limitations, standards, and other permit conditions (40 CFR Part 122.44(j)(2)(ii)) (PDF)(8 pp, 268 K)

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:

• Local Limits Development Guidance
• Local limits Development Guidance Appendices
• Region III Guidance for Setting Local Limits for a Pollutant Where the Domestic Loading Exceeds the Maximum Allowable Headworks Loading  –  Provides approaches POTWs can use to address situations in which the allowable industrial loading is calculated to be negative and establishes some guidelines on the Region’s expectations of POTWs.
• Sharing the Load: Effluent Trading for Indirect Dischargers  –  Details a case study of pretreatment local limits trading in the Passaic Valley Sewerage Commission service area, reported by EPA's Office of Policy, Planning and Evaluation; EPA Region 2; New Jersey Department of Environmental Protection; and a stakeholder group.
• Supplemental Manual on the Development and Implementation of Local Discharge Limitations under the Pretreatment Program: Residential and Commercial Toxic Pollutant Loadings and POTW Removal Efficiency Estimation  –  Provides information related to residential and commercial sources of toxic pollutants and estimated removal efficiencies of municipal treatment processes.
• EPA’s data sources when identifying pollution prevention and treatment technologies.
• Biosolids - Sewage Sludge
• EPA Water Quality Criteria
• Occupational Safety and Health Administration Permissible Exposure Limits

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