In general, the kind of permit a facility needs depends on how much air pollution the facility could emit, based on its equipment or processes.
Federal operating permits, required under Title V of the Clean Air Act are referred to interchangeably as Title V and Part 70 permits (Title V of the Clean Air Act is codified in Part 70 of the code of federal regulations). They are typically individual permits for the largest facilities that are written specifically for the activities (emission units, controls, etc.) at a facility. There is also a Part 70 general permit that covers manufacturing facilities. A general permit covers multiple entities with similar operations and types of emissions. Federal individual total facility permits are subject to a 30-day public comment period, followed by a 45-day EPA review period before they can be issued, and must be renewed every five years.
Some facilities that not covered by federal permits must still obtain state permits that regulate minor sources of air emissions.
- Individual state total facility permits address the specific activities (emission units, controls, etc.) at a facility. All individual total facility permits must be put on public notice for 30 days.
- Registration permits are for facilities with low actual emissions compared to their potential emissions. In general, the facility's actual emissions must be less than 50% of the federal thresholds. These are single page permits with requirements outlined in state rules that allow modifications as long as the facility continues to qualify for the permit.
- Capped emission permits are for non-complex facilities that do not qualify for a registration permit and require site-specific permit conditions. The facility’s actual emissions must be less than 75% to 90% of the federal thresholds. Like registration permits, these are single page permits with requirements outlined in state rules that allow modifications as long as the facility continues to qualify for the permit.
- State general permits cover multiple entities with similar operations and types of emissions. One state general permit, for non-metallic mineral processing, is currently available.
State permits generally do not expire, but the MPCA can make a state permit expire in certain circumstances. It can take anywhere from six months to a year or longer to issue individual total facility permits.
Modifications for general, registration, and capped permits are pre-authorized, provided the facility still qualifies for the same permit. Modifying a facility with an individual Part 70 or state permit may require a permit amendment, based on the potential to emit of the modified facility and state and federal regulations. Some amendment types require that the permit amendment be issued before construction or changes to the facility begins.
Some changes can be made without an amendment, including those qualifying as an insignificant modification, changes contravening permit terms, and certain replacements. Major amendments must be placed on public notice, can take six months or more to issue, and generally involve federal programs and other significant changes to air emissions.
Facilities with very low emissions
A permit may not be required for certain sources that have potential emissions that exceed permit thresholds but have very low actual emissions. These sources are called conditionally exempt sources, and could include auto body shops, coating, woodworking, gasoline service stations, and concrete manufacturers. Conditionally exempt facilities must follow technical standards and submit a notification.