DE MINIMIS DETERMINATIONS


FIRST, DE MINIMIS CATEGORIES MAY BE BASED ON "MINIMAL JUDGMENT" 

Minimal judgment means:

For a part 70 permit:
  incorporating the change requires "minimal judgment to assure compliance" with requirements
  that apply to the change [basically, this means that the monitoring requirements involve
  minimal judgment]
For a minor NSR permit:
  establishing the NSR requirements requires "minimal judgment"
 
Monitoring requirements with minimal judgment include the following --

Requirements to:
  Keep records of VOC content of coatings for compliance with a VOC content (lb/gal) limit
  Keep records of the use or integrity of passive control devices, such as seals, lids or roofs; use
  of low-polluting fuels or feedstocks; and use of combustion design features or characteristics
  Use fugitive dust control measures, such as watering of roads
  Keeps records of inspection, maintenance, and repair
  Keep records of pollution prevention measures
  Keep records of proper operation of a process, such as ensuring lids are in place on vapor
  degreasers
  Other requirements similar to those listed above 


"Minimal judgment to establish NSR requirements" include: 

   Rules applicable to source categories, such as VOC limits on surface coating operations, for
  which the monitoring is adequate or involves "minimal judgment to assure compliance" (see
  above list)
  Generic rules, such as opacity limits, process weight tables, or SIP prohibitions against
  violating the NAAQS
  Approvals to construct, where the approval establishes no new requirements
  Registrations for purposes of tracking equipment or emissions 
  Other requirements similar to those listed above 

Examples of how to apply the minimal judgment criterion

  A State has minor NSR rules that apply categorically to certain small sources.  Since these are
  within the listed NSR requirements involving minimal judgment, the State can exempt them
  from the public review requirements of part 51.  To exempt them from public and EPA review
  under part 70, the State must also determine either that:
     1)  the rules contain adequate monitoring to assure compliance, or 
     2)  any monitoring that needs to be added in the title V permit involves the sort of minimal
     judgment monitoring listed above 

  A State exempts sources below 15 tpy from its NSR program (so they are already exempt
  from public review requirements of part 51.  Some of the exempted sources are subject to
  NSPS requirements that are not listed on Appendix B as eligible for notice-only revisions, due
  to lack of monitoring.  To exempt these sources from public and EPA review requirements of
  part 70, the State must show that the monitoring requirements needed in the title V permit
  involve minimal judgment of the sort listed above.

IN ADDITION, DE MINIMIS CATEGORIES CAN BE BASED ON TRIVIAL
ENVIRONMENTAL IMPACT 

"Trivial environmental impact" means: 

Either of the following:
  1) the PTE of the change is below EPA's presumptive level of 25 percent of significance
     values, OR
  2) the change is below a cutoff level shown by the State to have trivial environmental impact


If the State chooses to establish its own cutoff level, it must:

Show that changes below the State cutoff level have a trivial environmental impact with respect to
all of the following that are relevant:
  The ability of attainment areas are able to remain attainment, and nonattainment areas to
  achieve attainment status
  The effect on consumption of PSD increments
  The impact on Class I areas
  The impact of de minimis changes on areas of special concern, such as schools, hospitals or
  other areas for which the public has expressed a desire to participate in permit decisions

Examples of how to apply the "trivial environmental impact" criterion to State cutoff levels

  A State with large attainment areas and few sources establishes a de minimis cutoff level at the
  PSD significance levels.  Based on earlier modeling from the SIP, the State shows that a
  changes below these levels has a trivial impact on the ability to remain attainment and PSD
  increment consumption.  In addition, based on analysis of several sources recently locating
  near its Class I areas, the State shows that changes below the cutoff would have a trivial
  impact on Class I areas.  The State has also identified several areas of special concern and has
  established a lower cutoff level for those which satisfies the public's need to participate in
  future permit decisions affecting those areas.

  A State comprised on only nonattainment areas establishes a de minimis cutoff level of 50
  percent of significance levels.  It performs modeling to show that emissions expected from
  changes below the 50 percent cutoff will have a trivial impact on its ability to achieve
  attainment by the SIP deadline.  It also performs outreach to public groups that have
  expressed past concern about pollution in certain areas.  It shows the groups that emissions of
  criteria pollutants below the 50 percent level would have a trivial impact on the areas the
  public is concerned about.