| #D001 | | direct dischargers | A point source that discharges pollutants to waters of the United States, such as streams, lakes, or oceans. | high |
| #D002 | | indirect dischargers | A facility that discharges pollutants to a publicly owned treatment works (municipal sewage treatment plant). | high |
| #D003 | | Aluminum forming | Aluminum forming is the deformation of aluminum or alloys into specific shapes by hot or cold working such as rolling, extrusion, forging, and drawing. Also included are a number of ancillary operations such as casting, heat treatment, and surface treatment that are an integral part of aluminum forming processes and that can contribute significantly to the wastewater discharged from aluminum forming plants. | medium |
| #D004 | | small extrusion and small drawing with emulsions or soaps facilities | Extrusion facilities that extrude less than 3 million pounds of product per year and draw with emulsions or soaps less than 1 million pounds per year [40 CFR 467.01(c)] | high |
| #D005 | | NAICS | North American Industrial Classification System | high |
| #D006 | | TTO | total toxic organics | high |
| #D007 | | surface treatment | For the purposes of this regulation, surface treatment is considered to be a part of the Aluminum Forming Category whenever it is performed as an integral part of aluminum forming. All surface treatment of aluminum is considered to be an integral part of Aluminum Forming whenever it is performed at the same plant site at which aluminum is formed, and such operations are not considered for regulation under the Electroplating (40 CFR Part 413) or Metal Finishing (40 CFR Part 433) categories. | high |
| #D008 | | core operations | The core operations include the forming operation along with processes that are either closely linked with that forming operation or generate very little or no wastewater. | high |
| #D009 | | POTWs | publicly owned treatment works | high |