Grain Elevator

In September 2014, the Iowa Department of Natural Resources (DNR) adopted the federal standard for the National Emission Standards for Hazardous Air Pollutants for Prepared Feeds Manufacturing at Area Sources 40 CFR 63 Subpart DDDDDDD, otherwise known as the 7D Rule. This regulation applies to facilities that manufacture prepared animal feed or additives for animal feed (sometimes known as a “feed mill”) and use materials (such as additives or pre-mixes) containing chromium or manganese.

Basic Requirements for Compliance

  1. Perform housekeeping to minimize dust where materials containing chromium or manganese are stored, used or handled
  2. Maintain and operate all processes in accordance with manufacturers' specifications

General Information


  • 7D Notification of Compliance Status/Exemption Notification form (PDF) / (DOC)

Permitting Instructions and Guidance

  • Permit Guidance for Facilities using the Small Unit Exemption (SUE) (PDF)
  • Permit Guidance for Facilities not using the Small Unit Exemption (SUE) (PDF)
  • Emissions Calculator for Prepared Feeds Facilities (EXCEL)
    • To be used with the Permit Guidance documents
  • Feed Mill Fee FAQ (PDF)