July 2013: Air Permits, Part One

This is the tenth article in a series about air quality in general and how it applies to Indiana. This article and the next will discuss the various types, or levels, of Indiana air permits.

To provide some background, if a facility has one or more units that emit gasses or fine particles, it will probably need to obtain some type of an air permit from IDEM for the construction and operation of those units. The types of units that may require some level of approval include, but are not limited to, large industrial boilers; electric generating units that combust fossil fuel such as natural gas, coal or oil; grain silos; commercial painting or powder coating operations; commercial graphics operations; landfill gas ventilation systems; petroleum or chemical storage tanks; gravel and stone crushing equipment; coal processing equipment; wood processing equipment; and metal cleaning operations.

As discussed in a previous article, the type of approval a source, or facility, needs to have will depend on potential emissions (PTE) from its units or operations. Some units have such a small potential to generate emissions that the facility operating them is exempt from permitting requirements. For units that are not exempt, new facilities must obtain approval for construction and operation. There are three primary types of approvals in Indiana: registrations; state operating permits; and Title V permits, which are issued for pollution control at large sources under Title V of the federal Clean Air Act.

IDEM processes the permit applications for all three types of operating permits, and all three require IDEM to write a permit, issue a public notice (allowing for public review and comment), and make a final decision within a certain timeframe. However, the Title V permitting process also requires the federal government to issue a public notice and make a decision about the permit. This is an aspect of the permitting process that makes a Title V permit somewhat unique.

This article provides an introduction to exemptions, registrations and state operating permits. Title V permits will be covered in greater detail in the next article.

Construction and Operation of Sources That Are Exempt From Permitting Requirements

An emission source, or facility, is exempt from air permitting requirements if all of the emission units at the facility are exempt. State rules found in Title 326, Article 2-1.1-3 of the Indiana Administrative Code list exempt units, processes and operations and thresholds.

The minimum thresholds for pollutants facilities must control are outlined in the Registration Thresholds Table below. A source that submits an application that demonstrates to IDEM, or from which IDEM may determine, that the source’s potential to emit, or PTE, is below all the registration thresholds will be provided with a Letter of Exemption from IDEM. This is a voluntary decision on the part of the facility to apply for the Letter of Exemption. An exempt source can construct and operate without IDEM approval.

The Letter of Exemption from IDEM verifies that there are no construction conditions to be met, so long as the source does not engage in further construction to expand its PTE above registration levels or beyond. The source may be subject to applicable regulations, and IDEM includes those regulations in the Letter of Exemption, as a service.

Construction and Operation of Sources Requiring a Registration

The Registrations Thresholds Table (below) also displays the range of PTE thresholds for a Registration. Sources whose PTE is equal to or greater than the minimum threshold (middle column) of any one of the pollutants listed in the table, but also less than the maximum threshold (right-hand column) for all of the pollutants listed in the table, must obtain a Registration from IDEM.

Construction and Operation of Sources Requiring a State Operating Permit

Where the PTE for new operations is above the thresholds for a Registration, IDEM will issue a permit document that serves as both the construction and operating permit. The three most commonly required operating permits are the Minor Source Operating Permit (MSOP), the Federally Enforceable State Operating Permit (FESOP), or the Title V Operating Permit.

Details on the applicability of each of these types of construction and operating permits are provided in the Indiana Administrative Code at 326 IAC 2-6.1-6, 326 IAC 2-8-10 and 326 IAC 2-8-11.1.

Registrations Thresholds Table
Pollutants Minimum Threshold (Potential to Emit Equal to, or greater than) in Tons/Year Maximum Threshold (But less than) in Tons/Year
(VOCs) Volatile Organic Compounds for sources not required to use air pollution control equipment to comply with the VOC emission rules 10 25
(VOCs) Volatile Organic Compounds for sources that are required to use air pollution control equipment to comply with the VOC emission rules 5 25
(NOX) Nitrogen dioxide and oxides of nitrogen 10 25
(CO) Carbon monoxide 25 100
(SO2) Sulfur dioxide 10 25
Particulate Matter 5 25
(PM-10) Particulate matter less than 10 microns 5 25
Lead 0.2 (400 pounds) 5
Fluorides 5 25
Hydrogen Sulfide 5 25
Total Reduced Sulfur 5 25
Reduced Sulfur Compounds 5 25

More information on the federal Clean Air Act, including permits, is contained in the U.S. EPA Plain English Guide to the Clean Air Act.

Keith Baugues