On September 1, 2021, EPA Region 7 responded to a request from the Iowa Department of Natural Resources (IDNR) for guidance on the handling of the “relaxation” provisions of 40 CFR 52.21(r)(4). Historically, this has been an uncertain issue. With certain caveats discussed below, EPA clarified that the 52.21(r)(4) rule does not apply if the PSD source has or will become “minor.” EPA also stated that there is no “time period” that the source must be minor before a PSD limit may be relaxed. EPA also stated that PSD determinations should be based “on the facility’s status at the time of the new project” and that the NSR regulations do not require “reinstatement” of the 52.21(r)(4) limits if the source subsequently becomes major again. It is likely that similar principles would apply to NNSR....Read More
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