Title 40 · EPA

Metal Molding And Casting Point Source Category

40 C.F.R. Part 464 · Updated July 1, 2025

§ 464.01 — Applicability.

(a) This part applies to metal molding and casting facilities that discharge or may discharge pollutants to waters of the United States or that introduce pollutants into a publicly owned treatment works.

§ 464.02 — General definitions.

In addition to the definitions set forth in 40 CFR part 401, the following definitions apply to this part:

(a) Aluminum casting. The remelting of aluminum or an aluminum alloy to form a cast intermediate or final product by pouring or forcing the molten metal into a mold, except for ingots, pigs, or other cast shapes related to nonferrous (primary and secondary) metals manufacturing (40 CFR part 421) and aluminum forming (40 CFR part 467). Processing operations following the cooling of castings not covered under aluminum forming, except for grinding scrubber operations which are covered here, are covered under the electroplating and metal finishing point source categories (40 CFR parts 413 and 433).

(b) Copper casting. The remelting of copper or a copper alloy to form a cast intermediate or final product by pouring or forcing the molten metal into a mold, except for ingots, pigs, or other cast shapes related to nonferrous (primary and secondary) metals manufacturing (40 CFR part 421). Also excluded are casting of beryllium alloys in which beryllium is present at 0.1 or greater percent by weight and precious metals alloys in which the precious metal is present at 30 or greater percent by weight. Except for grinding scrubber operations which are covered here, processing operations following the cooling of castings are covered under the electroplating and metal finishing point source categories (40 CFR parts 413 and 433).

(c) Ferrous casting. The remelting of ferrous metals to form a cast intermediate or finished product by pouring the molten metal into a mold. Except for grinding scrubber operations which are covered here, processing operations following the cooling of castings are covered under the electroplating and metal finishing point source categories (40 CFR parts 413 and 433).

(d) Zinc casting. The remelting of zinc or zinc alloy to form a cast intermediate or final product by pouring or forcing the molten metal into a mold, except for ingots, pigs, or other cast shapes related to nonferrous (primary) metals manufacturing (40 CFR part 421) and nonferrous metals forming (40 CFR part 471). Processing operations following the cooling of castings not covered under nonferrous metals forming are covered under the electroplating and metal finishing point source categories (40 CFR parts 413 and 433).

(e) POTW shall mean “publicly owned treatment works.”

(f) A non-continuous discharger is a plant which does not discharge pollutants during specific periods of time for reasons other than treatment plant upset, such periods being at least 24 hours in duration. A typical example of a non-continuous discharger is a plant where wastewaters are routinely stored for periods in excess of 24 hours to be treated on a batch basis. For non-continuous discharging direct discharging plants, NPDES permit authorities shall apply the mass-based annual average effluent limitations or standards and the concentration-based maximum day and maximum for monthly average effluent limitations or standards established in the regulations. POTWs may elect to establish concentration-based standards for non-continuous discharges to POTWs. They may do so by establishing concentration-based pretreatment standards equivalent to the mass-based standards provided in §§ 464.15, 464.16, 464.25, 464.26, 464.35, 464.36, 464.45, and 464.46 of the regulations. Equivalent concentration standards may be established by following the procedures outlined in § 464.03(b).

(g) Total phenols shall mean total phenolic compounds as measured by the procedure listed in 40 CFR part 136 (distillation followed by colorimetric—4AAP).

(h) Sm 3 shall mean standard cubic meters.

(i) SCF shall means standard cubic feet.

(j) Total toxic organics (TTO) shall mean the sum of the mass of each of the toxic organic compounds which are found at a concentration greater than 0.010 mg/l. The specialized definitions for each subpart contain a discrete list of toxic organic compounds comprising TTO for each process segment in which TTO is regulated.

§ 464.03 — Monitoring and reporting requirements.

(a) As an alternative to monitoring for TTO (total toxic organics), an indirect discharging plant may elect to monitor for Oil and Grease instead. Compliance with the Oil and Grease standard shall be considered equivalent to complying with the TTO standard. Alternate Oil and Grease standards are provided as substitutes for the TTO standards provided in §§ 464.15, 464.16, 464.25, 464.26, 464.35, 464.36, 464.45, and 464.46.

(b) POTWs may establish concentration standards rather than mass standards, but must ensure that the concentration standards are exactly equivalent to the mass-based standards provided in §§ 464.15, 464.16, 464.25, 464.26, 464.35, 464.36, 464.45, and 464.46. Equivalent concentration standards may be determined by multiplying the mass-based standards included in the regulations by an appropriate measurement of average production, raw material usage, or air scrubber flow (kkg of metal poured, kkg of sand reclaimed, or standard cubic meters of air scrubbed) and dividing by an appropriate measure of average discharge flow to the POTW, taking into account the proper conversion factors to ensure that the units (mg/l) are correct.

(c) The “monthly average” regulatory values shall be the basis for the monthly average effluent limitations guidelines and standards in direct discharge permits and for pretreatment standards. Compliance with the monthly average effluent limitations guidelines and standards is required regardless of the number of samples analyzed and averaged.

§ 464.04 — Compliance date for PSES.

The compliance date of PSES is October 31, 1988.

§ 464.10 — Applicability; description of the aluminum casting subcategory.

The provisions of this subpart are applicable to discharges to waters of the United States and to the introduction of pollutants into publicly owned treatment works resulting from aluminum casting operations as defined in § 464.02(a).

§ 464.11 — Specialized definitions.

For the purpose of this subpart:

(a) Total toxic organics (TTO). TTO is a regulated parameter under PSES (§ 464.15) and PSNS (§ 464.16) for the aluminum subcategory and is comprised of a discrete list of toxic organic pollutants for each process segment where it is regulated, as follows:

(1) Casting Quench (§§ 464.15(b) and 464.16(b)):

(2) Die Casting (§ 464.15(c) and § 464.16(c)):

(3) Dust Collection Scrubber (§ 464.15(d) and § 464.16(d)):

(4) Investment Casting (§ 464.15(f) and § 464.16(f)):

(5) Melting Furnace Scrubber (§ 464.15(g) and § 464.16(g)):

(6) Mold Cooling (§ 464.15(h) and § 464.16(h)):

§ 464.12 — Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available.

Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available, except that non-continuous dischargers shall not be subject to the maximum day and maximum for monthly average mass (kg/1,000 kkg or lb/million lb of metal poured; kg/62.3 million Sm 3 or lb/billion SCF of air scrubbed) effluent limitations for copper, lead, zinc, total phenols, oil and grease, and TSS. For non-continuous dischargers, annual average mass limitations and maximum day and maximum for monthly average concentration (mg/l) limitations shall apply. Concentration limitation and annual average mass limitation shall only apply to non-continuous dischargers.

(a) Casting Cleaning Operations.

(b) Casting Quench Operations.

(d) Dust Collection Scrubber Operations.

(e) Grinding Scrubber Operations. No discharge of process wastewater pollutants to navigable waters.

(f) Investment Casting.

(g) Melting Furnace Scrubber Operations.

(h) Mold Cooling Operations.

§ 464.13 — Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best available technology economically achievable.

Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best available technology economically achievable, except that non-continuous dischargers shall not be subject to the maximum day and maximum for monthly average mass (kg/1,000 kkg or lb/million lb of metal poured; kg/62.3 million Sm 3 or lb/billion SCF of air scrubbed) effluent limitations for copper, lead, zinc, and total phenols. For non-continuous dischargers, annual average mass limitations and maximum day and maximum for monthly average concentration (mg/l) limitations shall apply. Concentration limitations and annual average mass limitations shall only apply to non-continuous dischargers.

(a) Casting Cleaning Operations.

(b) Casting Quench Operations.

(d) Dust Collection Scrubber Operations.

(e) Grinding Scrubber Operations. No discharge of process wastewater pollutants to navigable waters.

(f) Investment Casting.

(g) Melting Furnace Scrubber Operations.

(h) Mold Cooling Operations.

§ 464.14 — New source performance standards.

Any new source subject to this subpart must achieve the following new source performance standards (NSPS), except that non-continuous dischargers shall not be subject to the maximum day and maximum for monthly average mass (kg/1,000 kkg or lb/million lb of metal poured; kg/62.3 million Sm 3 or lb/billion SCF of air scrubbed) effluent standards for copper, lead, zinc, total phenols, oil and grease, and TSS. For non-continuous dischargers, annual average mass standards and maximum day and maximum for monthly average concentration (mg/l) standards shall apply. Concentration standards and annual average mass standards shall only apply to non-continuous dischargers.

(a) Casting Cleaning Operations.

(b) Casting Quench Operations.

(d) Dust Collection Scrubber Operations.

(e) Grinding Scrubber Operations. No discharge of process wastewater pollutants to navigable waters.

(f) Investment Casting.

(g) Melting Furnace Scrubber Operations.

(h) Mold Cooling Operations.

§ 464.15 — Pretreatment standards for existing sources.

Except as provided in 40 CFR 403.7 and 403.13, any existing source subject to this subpart which introduces pollutants into a publicly owned treatment works must comply with 40 CFR part 403 and achieve the following pretreatment standards for existing sources.

(a) Casting Cleaning Operations.

(b) Casting Quench Operation.

(d) Dust Collection Scrubber Operations.

(e) Grinding Scrubber Operations. No discharge of process wastewater pollutants to a POTW.

(f) Investment Casting.

(g) Melting Furnace Scrubber Operations.

(h) Mold Cooling Operations.

§ 464.16 — Pretreatment standards for new sources.

Except as provided in 40 CFR 403.7, any new source subject to this subpart which introduces pollutants into publicly owned treatment works must comply with 40 CFR part 403 and achieve the following pretreatment standards for new sources.

(a) Casting Cleaning Operations.

(b) Casting Quench Operations.

(d) Dust Collection Scrubber Operations.

(e) Grinding Scrubber Operations. No discharge of process wastewater pollutants to a POTW.

(f) Investment Casting.

(g) Melting Furnace Scrubber Operations.

(h) Mold Cooling Operations.

§ 464.17 — Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best conventional pollutant control technology. [Reserved]

§ 464.20 — Applicability; description of the copper casting subcategory.

The provisions of this subpart are applicable to discharges to waters of the United States and to the introduction of pollutants into publicly owned treatment works resulting from copper casting operations as defined in § 464.02(b).

§ 464.21 — Specialized definitions.

For the purpose of this subpart:

(a) Total Toxic Organics (TTO). TTO is a regulated parameter under PSES (§ 464.25) and PSNS (§ 464.26) for the copper subcategory and is comprised of a discrete list of toxic organic pollutants for each process segment where it is regulated, as follows:

(1) Casting Quench (§§ 464.25(a) and 464.26(a)):

(2) Dust Collection Scrubbers (§ 464.25(c) and 464.26(c)):

(3) Investment Casting (§ 464.25(e) and § 464.26(e)):

(4) Melting Furnace Scrubber (§ 464.25(f) and § 464.26(f)):

(5) Mold Cooling (§ 464.25(g) and § 464.26(g)):

§ 464.22 — Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available.

Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available, except that non-continuous dischargers shall not be subject to the maximum day and maximum for monthly average mass (kg/1,000 kkg or lb/million lb of metal poured; kg/62.3 million Sm 3 or lb/billion SCF of air scrubbed) effluent limitations for copper, lead, zinc, total phenols, oil and grease, and TSS. For non-continuous dischargers, annual average mass limitations and maximum day and maximum for monthly average concentration (mg/l) limitations shall apply. Concentration limitations and annual average mass limitations shall only apply to non-continuous dischargers.

(a) Casting Quench Operations.

(b) Direct Chill Casting Operations.

(d) Grinding Scrubber Operations. No discharge of process wastewater pollutants to navigable waters.

(e) Investment Casting.

(f) Melting Furnace Scrubber Operations.

(g) Mold Cooling Operations.

§ 464.23 — Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best available technology economically achievable.

Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best available technology economically achievable, except that non-continuous dischargers shall not be subject to the maximum day and maximum for monthly average mass (kg/1,000 kkg or lb/million lb of metal poured; kg/62.3 million Sm 3 or lb/billion SCF of air scrubbed) effluent limitations for copper, lead, zinc, and total phenols. For non-continuous discharges, annual average mass limitations and maximum day and maximum for monthly average concentration (mg/l) limitations shall apply. Concentration limitations and annual average mass limitations shall only apply to non-continuous dischargers.

(a) Casting Quench Operations.

(b) Direct Chill Casting Operations.

(d) Grinding Scrubber Operations. No discharge of process wastewater pollutants to navigable waters.

(e) Investment Casting.

(f) Melting Furnace Scrubber Operations.

(g) Mold Cooling Operations.

§ 464.24 — New source performance standards.

(a) Casting Quench Operations.

(b) Direct Chill Casting Operations.

(d) Grinding Scrubber Operations. No discharge of process wastewater pollutants to navigable waters.

(e) Investment Casting.

(f) Melting Furnace Scrubber Operations.

(g) Mold Cooling Operations.

§ 464.25 — Pretreatment standards for existing sources.

(a) Casting Quench Operations.

(b) Direct Chill Casting Operations.

(d) Grinding Scrubber Operations. No discharge of process wastewater pollutants to a POTW.

(e) Investment Casting.

(f) Melting Furnace Scrubber Operations.

(g) Mold Cooling Operations.

§ 464.26 — Pretreatment standards for new sources.

(a) Casting Quench Operations.

(b) Direct Chill Casting Operations.

(d) Grinding Scrubber Operations. No discharge of process wastewater pollutants to a POTW.

(e) Investment Casting.

(f) Melting Furnace Scrubber Operations.

(g) Mold Cooling Operations.

§ 464.27 — Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best conventional pollutant control technology. [Reserved]

§ 464.30 — Applicability; description of the ferrous casting subcategory.

The provisions of this subpart are applicable to discharges to waters of the United States and to the introduction of pollutants into publicly owned treatment works resulting from ferrous casting operations as defined in § 464.02(c).

§ 464.31 — Specialized definitions.

For the purpose of this subpart:

(a) Total Toxic Organics (TTO). TTO is a regulated parameter under PSES (§ 464.35) and PSNS (§ 464.36) for the ferrous subcategory and is comprised of a discrete list of toxic organic pollutants for each process segment where it is regulated, as follows:

(1) Casting Quench (§§ 464.35(b) and 464.36(b)):

(2) Dust Collection Scrubber (§§ 464.35(c) and 464.36(b)):

(3) Investment Casting (§§ 464.35(e) and 464.36(e)):

(4) Melting Furnace Scrubber (§§ 464.35(f) and 464.36(f)):

(5) Mold Cooling (§§ 464.35(g) and 464.36(g)):

(6) Slag Quench (§§ 464.35(h) and 464.36(h)):

(7) Wet Sand Reclamation (§§ 464.35(i) and 464.36(i)):

(b) Cast Iron. An iron containing carbon in excess of the solubility in the austentite that exists in the alloy at the eutectic temperature. Cast iron also is defined here to include any iron-carbon alloys containing 1.2 percent or more carbon by weight.

(c) Ductile Iron. A cast iron that has been treated while molten with a master alloy containing an element such as magnesium or cerium to induce the formation of free graphite as nodules or spherules, which imparts a measurable degree of ductility to the cast metal.

(d) Gray Iron. A cast iron that gives a gray fracture due to the presence of flake graphite.

(e) Malleable Iron. A cast iron made by a prolonged anneal of white cast iron in which decarburization or graphitization, or both, take place to eliminate some or all of the cementite. Graphite is present in the form of temper carbon.

(f) Steel. An iron-base alloy containing carbon, manganese, and often other alloying elements. Steel is defined here to include only those iron-carbon alloys containing less than 1.2 percent carbon by weight.

(g) The “primary metal cast” shall mean the metal that is poured in the greatest quantity at an individual plant.

(h) Multiple Ferrous Melting Furnace Scrubber Configuration. A multiple ferrous melting furnace scrubber configuration is a configuration where two or more discrete wet scrubbing devices are employed in series in a single melting furnace exhaust gas stream. The ferrous melting furnace scrubber mass allowance shall be given to each discrete wet scrubbing device that has an associated wastewater discharge in a multiple ferrous melting furnace scrubber configuration. The mass allowance for each discrete wet scrubber shall be identical and based on the air flow of the exhaust gas stream that passes through the multiple scrubber configuration.

(i) Discrete Wet Scrubbing Device. A discrete wet scrubbing device is a distinct, stand-alone device that removes particulates and fumes from a contaminated gas stream by bringing the gas stream into contact with a scrubber liquor, usually water, and from which there is a wastewater discharge. Examples of discrete wet scrubbing devices are: Spray towers and chambers, venturi scrubbers (fixed and variable), wet caps, packed bed scrubbers, quenchers, and orifice scrubbers. Semi-wet scrubbing devices where water is added and totally evaporates prior to dry air pollution control are not considered to be discrete wet scrubbing devices. Ancillary scrubber operations such as fan washes and backwashes are not considered to be discrete wet scrubber devices. These ancillary operations are covered by the mass limitations of the associated scrubber. Aftercoolers are not considered to be discrete wet scrubbing devices, and water discharges from aftercooling are not regulated as a process wastewater in this category.

§ 464.32 — Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available.

Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available, except that non-continuous dischargers shall not be subject to the maximum day and maximum for monthly average mass (kg/1,000 kkg or lb/million lb of metal poured; kg/1,000 kkg or lb/million lb of sand reclaimed; kg/62.3 million Sm 3 or lb/billion SCF of air scrubbed) effluent limitations for copper, lead, zinc, total phenols, oil and grease, and TSS. For non-continuous dischargers, annual average mass limitations and maximum day and maximum for monthly average concentration (mg/l) limitations shall apply. Concentration limitations and annual average mass limitations shall only apply to non-continuous dischargers.

(a) Casting Cleaning Operations.

(b) Casting Quench Operations.

(d) Grinding Scrubber Operations. No discharge of process wastewater pollutants to navigable waters.

(e) Investment Casting.

(f) Melting Furnace Scrubber Operations.

(g) Mold Cooling Operations.

(h) Slag Quench Operations.

(i) Wet Sand Reclamation Operations.

§ 464.33 — Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best available technology economically achievable.

Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best available technology economically achievable, except that non-continuous dischargers shall not be subject to the maximum day and maximum for monthly average mass (kg/1,000 kkg or lb/million lb of metal poured; kg/1,000 kkg or lb/million lb of sand reclaimed; kg/62.3 million Sm 3 or lb/billion SCF of air scrubbed) effluent limitations for copper, lead, zinc, and total phenols. For non-continuous dischargers, annual average mass limitations and maximum day and maximum for monthly average concentration (mg/l) limitations shall apply. Concentration limitations and annual average mass limitations shall only apply to non-continuous dischargers.

(a) Casting Cleaning Operations. (1) Applicable to plants that are casting primarily ductile or gray iron and to plants that are casting primarily malleable iron where greater than 3,557 tons of metal are poured per year.