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Interim Approval Information

An interim approval allows the applicant, under certain limited circumstances and at their own risk, to commence construction of a new emissions unit at an existing source or modification of an emissions unit at an existing source while the permit application is being reviewed. Interim approvals are subject to the requirements of 326 IAC 2-13-1 [PDF].

While the applicant must consent to the federal enforceability of an interim approval pursuant to 326 IAC 2-13-1(c)(2)(D), EPA has not approved 326 IAC 2-13 (Interim Approvals) as part of IDEM OAQ’s State Implementation Plan (SIP).


The interim petition is applicable to a proposed modification/revision to an existing source operating under a valid operating permit(s). The following modifications/revisions are ineligible for the interim petition program:

  • Construction of a new major PSD facility or major PSD modification to an existing source, or
  • Modification to an existing source in a nonattainment area that has the potential to emit a pollutant for which the nonattainment designation is based in an amount exceeding the levels of emissions that require a permit revision for that pollutant, or
  • Construction of a totally new plant, or
  • Any modification that is subject to 326 IAC 2-4.1 [PDF] (New Source Toxics Control).

Guidance for Applicants


Companies who plan to obtain an interim approval should contact IDEM’s Office of Air Quality (OAQ) to discuss their plans and requirements prior to submitting a petition. In addition, owners, operators and their representatives may contact IDEM's Compliance and Technical Assistance Program (CTAP) for free and confidential assistance concerning compliance requirements or for help choosing and completing application forms.

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