Effluent Guidelines

Metal Products and Machinery Effluent Guidelines

""EPA promulgated the Metal Products and Machinery (MP&M) Effluent Guidelines and Standards in 2003. The regulation (40 CFR Part 438) applies to about 2,400 facilities that manufacture, rebuild, or maintain finished metal products, parts, or machines, and generate oily wastewater. The MP&M regulation covers only direct dischargersHelpdirect dischargerA point source that discharges a pollutant(s) to waters of the United States, such as streams, lakes, or oceans. These sources are subject to the National Pollutant Discharge Elimination System program regulations. Municipal and industrial facilities that introduce pollution through a defined conveyance or system such as outlet pipes are direct dischargers. and the requirements are incorporated into NPDES permits.

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Facilities Covered

In addition to some government facilities, the regulation sets performance standards for facilities in these industrial sectors:

  • Aerospace
  • Aircraft
  • Bus and Truck
  • Electronic Equipment
  • Hardware
  • Household Equipment
  • Instruments
  • Mobile Industrial Equipment
  • Motor Vehicle
  • Office Machine
  • Ordnance
  • Precious Metals and Jewelry
  • Railroad
  • Ships and Boats
  • Stationary Industrial Equipment
  • Miscellaneous Metal Products

Examples of federal, state, and local government facilities that fall under this rule are a town that operates its own bus, truck, and/or snow removal equipment maintenance facility or a U.S. military base.

Related Categories

  • Metal Finishing (40 CFR Part 433)
    Direct or indirect dischargers which perform any of the following: electroplating (except indirect discharging "job shops"), electroless plating, anodizing, coating, chemical etching and milling, printed circuit board manufacture (captive facilities only)
  • Electroplating (40 CFR Part 413)
    "Job shop" electroplaters and independent printed circuit board manufacturers which are indirect dischargers

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Effluent Limitations and Technologies

The MP&M effluent limitations apply only to facilities that directly discharge wastewater from oily operations in the Oily Wastes subcategory. The regulation sets daily maximum limits for two pollutants, oil and grease (as hexane extractable material) and total suspended solidsHelptotal suspended solidsA measure of the filterable solids present in a sample, as determined by the method specified in 40 CFR Part 136., based on the best practicable control technology (BPT):
  1. In-process flow control and pollution prevention
  2. Oil-water separation by chemical emulsion breaking and skimming

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Regulatory History

  • Final Rule (May 13, 2003)
  • Documents, including:
    • Development Document
      Describes industry processes, pollutants generated, available control and treatment technologies, the technical basis for the final rule, and costs of the rule
    • Economic, Environmental and Benefits Analysis
  • Proposed Rule (January 3, 2001)
    • Re-proposal; replaces 1995 proposed rule
  • Proposed Rule (May 30, 1995)

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Additional Information

For additional information regarding MP&M effluent guidelines, please contact Ahmar Siddiqui (siddiqui.ahmar@epa.gov) or 202-566-1044.