In the three decades since its enactment, the Clean Air Act (CAA) has seen many skirmishes over how its text should be interpreted. A current, and major, one involves the extent to which a power plant or factory may alter its facilities or operations without bringing about a "modification" of that emissions source. A "modification" turns an existing emissions source into a "new source," which has to meet more stringent air pollution control requirements in the CAA than does an existing source. Legally speaking, the issue is—What changes to an "existing stationary source" of air pollution are significant enough to be a "modification" so as to trigger the CAA's New Source Performance Standards (NSPSs) and pre-construction "new source review" (NSR)? Our topic in this report, however, is narrower. It is the widely used exemption to what constitutes a modification for "routine maintenance, repair, and replacement" (RMRR) at stationary sources. This report surveys the original statutory, regulatory, and case law landscape on RMRR, then describes more recent regulatory and judicial developments. The PSD and nonattainment-area portions of the act, mandating NSR, are to similar effect.
A major Clean Air Act issue is the extent to which an existing power plant or factory may be altered without effecting a "modification." A "modification" of an existing air pollution source is subject to the act's stringent air pollution control requirements for new sources. The topic of this report is a widely used exemption to "modification" allowing changes that constitute "routine maintenance, repair, and replacement" without triggering such stringent requirements. The report surveys the original legal landscape surrounding this exemption—in the contexts of determining applicability of New Source Performance Standards, and New Source Review in Prevention of Significant Deterioration and nonattainment areas. It then summarizes the many significant developments during the current Bush Administration, both in the Federal Register and in the courts. This report will be updated as events warrant.