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Water: Casting

Effluent Guidelines: Metal Molding and Casting (Foundries) Industry

Metal Molding and Casting (Foundries) Industry


EPA promulgated wastewater discharge standards for the Metal Molding and Casting industry in October 1985. The regulations are published in the Code of Federal Regulations at 40 CFR Part 464. The regulations cover 28 process segments (processes such as casting quench, grinding scrubber, mold cooling) in four subcategories: Aluminum Casting, Copper Casting, Ferrous Casting, and Zinc Casting. The cast metals have unique properties that influence the way they are melted and processed and, thus, affect the process wastewater characteristics.

For three of the process segments, the technology basis of the regulations is no discharge of process wastewater pollutants. For the remaining 25 segments, the regulations are based on a combination of technologies such as high rate recycle, oil skimming, lime precipitation and settling, and filtration. Examples of the pollutants with effluent limits for Foundries are total suspended solids, phenols, copper, lead, and zinc, and also a bulk parameter (oil and grease) for monitoring total toxic organics (TTO) in all subcategories for indirect dischargers (see Section 464.03(a)).

What is Metal Molding and Casting?

The facilities covered by this rulemaking are often referred to as Foundries. A foundry produces metal castings from either ferrous or non-ferrous alloys. Metals are turned into parts by melting the metal into a liquid, pouring or injecting the metal in a mold, with the cavity of the mold representing, within close tolerances, the dimension of the finished product. One of the major advantages of this process is that intricate metal shapes, which are not easily obtained by any other method of fabrication, can be produced. Another advantage is the rapid translation of a projected design into a finished article.

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Facilities Covered

The facilities covered by the regulation include both "job shops"—plants that sold 50 percent or more of their production to customers outside the corporate entity and "captive plants"—plants that sold 50 percent or more of their products internally or were used within the corporate entity. The scope of the regulated industry, as reported here, reflects the Agency's data at the time the regulation was issued in 1985, which in turn was based on data from the late 1970's.

At the time EPA published these effluent limitations, we estimated that about 700 plants generated and discharged process wastewater. The facilities covered included both direct dischargers and plants that discharge to POTWs. The regulations for direct dischargers—those who discharge to surface waters—cover both continuous and intermittent discharges, although the effluent limitations vary by that distinction.

For indirect dischargers—those who discharge to POTWs, which is the larger number of plants—the effluent limits apply only to continuous dischargers. POTWs may elect to establish concentration-based standards for non-continuous discharges; details and instructions are included in the rulemaking support documents. Special care needs to be given to potential for overlap of applicability to metal molding and casting facilities with other categories, such as metal finishing (note particularly the presence or absence of six "core operations" that must be present for operations to be covered by metal finishing, Part 433), aluminum forming, and copper forming. Please review the Development Document regarding process operations and associated wastewaters covered in each subcategory (Sections 3 and 5) and the Appendices, notably Appendix C.

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Final Rule

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Guidance and Background Documents

Development Document

EPA-440-1-85/070; October 1985

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Additional Information/Contacts

For additional information regarding metal molding and casting industry effluent guidelines, please see the program manager for the Metal Molding and Casting industry.

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