EPA Permitting Regulations Vacated—Project Delays Expected   The
recent decision in Sierra Club v. EPA, 705 F.3d 458 (D.C. Cir.
2013) vacated all of EPA’s rules on Significant Monitoring
Concentrations (“SMCs”), as well as some (the Prevention of
Significant Deterioration (“PSD”) portion) of the Significant
Impact Levels (“SILs”) for Particulate Matter in air emissions
measuring 2.5 micrometers in diameter or smaller (“PM2.5”).  As
a result permit applicants have fewer screening tools available
when seeking exemption from analysis and monitoring requirements
under the Clean Air Act (“Act”).  A.   Background for the Act,
NAAQS, SIPs and PSD  The Act requires EPA to set National
Ambient Air Quality Standards (“NAAQS”) for harmful pollutants
at levels necessary to protect public health and welfare.  Under
the Act, EPA must designate areas as attainment, nonattainment,
or unclassifiable for each NAAQS. States have primary
responsibility for implementing the NAAQS, and must submit a
state implementation plan (“SIP