406.20—Applicability; description of the corn dry milling subcategory.
(a)
The provisions of this subpart are applicable to discharges resulting from the process in which shelled corn is washed and subsequently milled by dry processes into such products as corn meal, grits, flour, oil, and animal feed.
(b)
The provisions of this subpart do not apply to discharges from subsequent manufacturing operations to produce expanded or extruded feed or feed products.