On September 2, 2025, the EPA issued new guidance broadening the scope of construction that is allowed prior to a source obtaining a New Source Review (NSR) preconstruction permit. The NSR regulations prohibit stationary sources from “beginning actual construction” prior to obtaining this permit, which historically included a broad range of activities. Consequently, only limited activities such as site-clearing and grading were authorized according to historic EPA guidance. Now, EPA has provided a new interpretation of what it means for a site to “begin actual construction”.

In the September 2 guidance, EPA issued a case-specific determination explaining that “begin actual construction” prohibits only a narrow scope of construction: that related to the site’s emission unit. The September 2 interpretation was announced in a letter issued by the EPA to the Maricopa County Air Quality Department regarding the construction of a semiconductor manufacturing facility. EPA stated that the prohibition on beginning actual construction prior to obtaining an NSR permit only extends to construction related to the emissions unit itself. In this determination, EPA authorized the site to construct the “core and shell” of the facility prior to obtaining the NSR permit, “provided that the construction of this core and shell . . . does not involve the physical construction on an emission unit or the laying of underground piping or construction of supports and foundations that are part of any emissions unit.” This is broader than past guidance.

While this represents only one case specific determination, the agency announced it intends to formally revise the definition of “begin actual construction” through rulemaking in 2026. Should EPA finalize a similar interpretation as in this September 2 guidance, this would likely expedite project construction by allowing a broader scope of work to begin prior to obtaining the permit.