This subpart applies to discharges of pollutants to waters of the United States and introductions of pollutants into publicly owned treatment works from the core and the ancillary operations of the extrusion subcategory.

For the purpose of this subpart:

(a) The “core” of the extrusion subcategory shall include extrusion die cleaning, dummy block cooling, stationary casting, artificial aging, annealing, degreasing, and sawing.

(b) The term “extrusion die cleaning” shall mean the process by which the steel dies used in extrusion of aluminum are cleaned. The term includes a dip into a concentrated caustic bath to dissolve the aluminum followed by a water rinse. It also includes the use of a wet scrubber with the die cleaning operation.

(c) The term “ancillary operation” shall mean any operation not previously included in the core, performed on-site, following or preceding the extrusion operation. The ancillary operations shall include direct chill casting, press or solution heat treatment, cleaning or etching, degassing, and extrusion press hydraulic fluid leakage.

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:

(a) 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:

(b) There shall be no discharge allowance for wastewater pollutants from the degassing operation.

(c) The discharge of wastewater pollutants from the core and ancillary operation except those in (b) of this section, shall not exceed the values set forth below:

Any new source subject to this subpart must achieve the following performance standards.

(a) There shall be no discharge allowance for wastewater pollutants from the degassing operation.

(b) The discharge of wastewater pollutants from the core and ancillary operations except those listed in paragraph (a) shall not exceed the values set forth below:

(a) 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.

(b) There shall be no discharge allowance for wastewater pollutants from the degassing operation.

(c) The mass of wastewater pollutants from the core and ancillary operations except those identified in paragraph (b), introduced into a POTW shall not exceed the following values:

(a) Except as provided in 40 CFR 403.7, any new 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 new sources.

(b) There shall be no discharge allowance for wastewater pollutants from the degassing operation.

(c) The mass of wastewater pollutants from the core and ancillary operations except those identified in paragraph (b) introduced into a POTW shall not exceed the values set forth below: